| 1. |
- Ahmad, Khadija Mohamed, et al.
(författare)
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Small chromosomes among Danish Candida glabrata isolates originated through different mechanisms.
- 2013
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 1572-9699 .- 0003-6072. ; 104:1, s. 111-122
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Tidskriftsartikel (refereegranskat)abstract
- We analyzed 192 strains of the pathogenic yeast Candida glabrata from patients, mainly suffering from systemic infection, at Danish hospitals during 1985-1999. Our analysis showed that these strains were closely related but exhibited large karyotype polymorphism. Nine strains contained small chromosomes, which were smaller than 0.5 Mb. Regarding the year, patient and hospital, these C. glabrata strains had independent origin and the analyzed small chromosomes were structurally not related to each other (i.e. they contained different sets of genes). We suggest that at least two mechanisms could participate in their origin: (i) through a segmental duplication which covered the centromeric region, or (ii) by a translocation event moving a larger chromosome arm to another chromosome that leaves the centromere part with the shorter arm. The first type of small chromosomes carrying duplicated genes exhibited mitotic instability, while the second type, which contained the corresponding genes in only one copy in the genome, was mitotically stable. Apparently, in patients C. glabrata chromosomes are frequently reshuffled resulting in new genetic configurations, including appearance of small chromosomes, and some of these resulting "mutant" strains can have increased fitness in a certain patient "environment".
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| 2. |
- Bakeeva, Albina, et al.
(författare)
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Yeasts and bacteria associated with kocho, an Ethiopian fermented food produced from enset (Ensete ventricosum)
- 2019
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 112, s. 651-659
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Tidskriftsartikel (refereegranskat)abstract
- Enset (Ensete ventricosum) is the basis of the staple food consumed by about 20% of the Ethiopian population. Kocho is one of the food products generated from enset by spontaneous fermentation of decorticated and pulverized pseudostem and corm sections. We isolated culturable microbes associated with kocho from different stages of fermentation. Twelve yeast species, six lactic acid bacteria (LABs) species and eleven species of aerobic bacteria were identified by sequencing ITS/D1D2 regions of 26S rDNA of yeasts and 16S rDNA of bacteria, respectively. More yeast species were identified in fresh (fermented for 2-5days) kocho, compared to long-term (7-12months) fermented kocho, while we observed an opposite trend for LABs. In fresh kocho, the most frequently isolated yeast species were Pichia exigua, Galactomyces geotrichum, and Pichia fermentans. From mid-term (3-4months) kocho most frequently Candida cabralensis, G. geotrichum, and Candida ethanolica were isolated. In the long-term fermentations, the most frequently isolated yeast was Saturnispora silva. Lactobacillus plantarum was the most frequently isolated LAB in both fresh and mid-term kocho. In long-term fermented kocho, Acetobacter pasteurianus and L. plantarum were most frequently isolated. L. plantarum was consistently isolated from all the three stages of fermentation. Aerobic bacteria in fresh kocho were mostly gram-negative, with Raoultella planticola and Pantoea agglomerans being the most frequently isolated species. In long-term fermented kocho, mainly gram-positive, spore-forming bacteria of the genus Bacillus were found, among them also species of the Bacillus cereus group, Bacillus anthracis and Bacillus thurigiensis.
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| 3. |
- Bengtsson-Palme, Johan, 1985, et al.
(författare)
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Metaxa: a software tool for automated detection and discrimination among ribosomal small subunit (12S/16S/18S) sequences of archaea, bacteria, eukaryotes, mitochondria, and chloroplasts in metagenomes and environmental sequencing datasets
- 2011
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Ingår i: Antonie van Leeuwenhoek: international journal of general and molecular microbiology. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 100:3, s. 471-475
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Tidskriftsartikel (refereegranskat)abstract
- The ribosomal small subunit (SSU) rRNA gene has emerged as an important genetic marker for taxonomic identification in environmental sequencing datasets. In addition to being present in the nucleus of eukaryotes and the core genome of prokaryotes, the gene is also found in the mitochondria of eukaryotes and in the chloroplasts of photosynthetic eukaryotes. These three sets of genes are conceptually paralogous and should in most situations not be aligned and analyzed jointly. To identify the origin of SSU sequences in complex sequence datasets has hitherto been a time-consuming and largely manual undertaking. However, the present study introduces Metaxa (http://microbiology.se/software/metaxa/), an automated software tool to extract full-length and partial SSU sequences from larger sequence datasets and assign them to an archaeal, bacterial, nuclear eukaryote, mitochondrial, or chloroplast origin. Using data from reference databases and from full-length organelle and organism genomes, we show that Metaxa detects and scores SSU sequences for origin with very low proportions of false positives and negatives. We believe that this tool will be useful in microbial and evolutionary ecology as well as in metagenomics.
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| 4. |
- Casillo, Angela, et al.
(författare)
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Structural characterization of an all-aminosugar-containing capsular polysaccharide from Colwellia psychrerythraea 34H
- 2017
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 110:11, s. 1377-1387
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Tidskriftsartikel (refereegranskat)abstract
- Colwellia psychrerythraea strain 34H, a Gram-negative bacterium isolated from Arctic marine sediments, is considered a model to study the adaptation to cold environments. Recently, we demonstrated that C. psychrerythraea 34H produces two different extracellular polysaccharides, a capsular polysaccharide and a medium released polysaccharide, which confer cryoprotection to the bacterium. In this study, we report the structure of an additional capsular polysaccharide produced by Colwellia grown at a different temperature. The structure was determined using chemical methods, and one- and two-dimensional NMR spectroscopy. The results showed a trisaccharide repeating unit made up of only amino-sugar residues: N-acetyl-galactosamine, 2,4-diacetamido-2,4,6-trideoxy-glucose (bacillosamine), and 2-acetamido-2-deoxyglucuronic acid with the following structure: -> 4)-beta-d-GlcpNAcA-(1 -> 3)-beta-d-QuipNAc4NAc-(1 -> 3)-beta-d-GalpNAc-(1 ->. The 3D model, generated in accordance with H-1,H-1-NOE NMR correlations and consisting of ten repeating units, shows a helical structure. In contrast with the other extracellular polysaccharides produced from Colwellia at 4 A degrees C, this molecule displays only a low ice recrystallization inhibition activity.
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| 5. |
- Cooper, Callum, et al.
(författare)
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Virulence plasmid stability in environmentally occurring Bacillus anthracis from North East Turkey
- 2017
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 110:1, s. 167-170
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Tidskriftsartikel (refereegranskat)abstract
- The Bacillus anthracis virulence plasmid pXO2, which encodes for a polypeptide capsule, can be lost during long term laboratory storage. To determine if pXO2 is lost in nature we screened B. anthracis isolates obtained from B. anthracis spores from contaminated animal burial sites in Turkey for their ability to express a capsule upon primary culture. A total of 672 B. anthracis colonies were examined of which ten produced a mixed mucoid (capsule +ve)/non-mucoid (capsule -ve) phenotype and a further one colony yielded non-mucoid colonies upon repeated culture. Screening by PCR using pXO2 specific primers revealed that seven of these isolates had eliminated the plasmid. Of the four colonies which were positive by PCR, one regained the ability to express a capsule upon repeated culture suggesting that the defect was reversible. This is an important observation as capsule expression is a principal marker of virulence and in the absence of PCR serves as a key diagnostic marker. The results of this preliminary study suggest that pXO2 is lost in nature and that further studies are need to determine the mechanisms by which this occurs.
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| 6. |
- Corbacho, Isaac, et al.
(författare)
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Genome-wide expression profile of the mnn2Δ mutant of Saccharomyces cerevisiae
- 2006
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 89:3-4, s. 485-494
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The MNN2 gene of S. cerevisiae encodes an α (1,2) mannosyl transferase required for branching the outer chain of N-linked oligosaccharides (Rayner J.C. and Munro S. 1998. J. Biol. Chem. 273: 2683626843) and it also seems to have some effect on the transfer of mannosyl phosphate groups to the inner core (Olivero I. et al. 2000. FEBS Lett. 475: 111116). In order to reveal possible interactions of MNN2 expression with other cellular pathways, we analyzed the transcriptome of the deletion mutant S. cerevisiae mnn2Δ using cDNA microarrays. We found 151 genes that showed an altered expression level of ≥2-fold, 58 of them up-regulated and 93 down-regulated. Quite a high proportion of these genes (29%) encode unclassified proteins. In contrast to other defects affecting the integrity of the cell wall, deletion of MNN2 does not stimulate the expression of any of the genes included in the previously defined cell wall compensatory cluster (Lagorce et al. 2003. J. Biol. Chem. 278: 2034520357). We also found that 15% of the selected genes are related to central metabolic pathways. In addition, the mnn2Δ strain seems to have a certain level of stimulation of DNA processing reactions while some genes involved in intracellular transport pathways are under-regulated
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| 7. |
- Cotta, M. A., et al.
(författare)
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Two novel species Enterococcus lemanii sp nov and Enterococcus eurekensis sp nov., isolated from a swine-manure storage pit
- 2013
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Ingår i: Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology. - : Springer Science and Business Media LLC. - 0003-6072. ; 103:1, s. 89-98
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Tidskriftsartikel (refereegranskat)abstract
- A polyphasic taxonomic study using morphological, biochemical, chemotaxonomic and molecular genetic methods was performed on six strains of unknown Gram-positive, nonspore-forming, facultative anaerobic coccus-shaped bacteria isolated from a swine-manure storage pit. On the basis of the 16S rRNA, RNA polymerase alpha-subunit (rpoA) and 60 kDa chaperonin (cpn60) gene sequence analyses, it was shown that all the isolates were enterococci but formed two separate lines of descent. Pairwise 16S rRNA gene sequence comparisons demonstrated that the two novel organisms were most closely related to each other (97.9 %) and to Enterococcus aquimarinus (97.8 %). Both organisms contained major amounts of C-16:0, C-16:1 omega 7c, C-16:1 omega 7c, and C-18:1 omega 7c/12t/9t as the major cellular fatty acids. Based on biochemical, chemotaxonomic and phylogenetic evidence, the names Enterococcus lemanii sp. nov. (type strain PC32(T) = CCUG 61260(T) = NRRL B-59661(T)) and Enterococcus eurekensis sp. nov. (type strain PC4B(T) = CCUG 61259(T) = NRRL B-59662(T)) are proposed for these hitherto undescribed species.
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| 8. |
- Egervärn, Maria, et al.
(författare)
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Transferability of a tetracycline resistance gene from probiotic Lactobacillus reuteri to bacteria in the gastrointestinal tract of humans
- 2010
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 97, s. 189-200
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Tidskriftsartikel (refereegranskat)abstract
- The potential of Lactobacillus reuteri as a donor of antibiotic resistance genes in the human gut was investigated by studying the transferability of the tetracycline resistance gene tet(W) to faecal enterococci, bifidobacteria and lactobacilli. In a double-blind clinical study, seven subjects consumed L. reuteri ATCC 55730 harbouring a plasmid-encoded tet(W) gene (tet(W)-reuteri) and an equal number of subjects consumed L. reuteri DSM 17938 derived from the ATCC 55730 strain by the removal of two plasmids, one of which contained the tet(W) gene. Faecal samples were collected before, during and after ingestion of 5 x 10(8) CFU of L. reuteri per day for 14 days. Both L. reuteri strains were detectable at similar levels in faeces after 14 days of intake but neither was detected after a two-week wash-out period. After enrichment and isolation of tetracycline resistant enterococci, bifidobacteria and lactobacilli from each faecal sample, DNA was extracted and analysed for presence of tet(W)-reuteri using a real-time PCR allelic discrimination method developed in this study. No tet(W)-reuteri signal was produced from any of the DNA samples and thus gene transfer to enterococci, bifidobacteria and lactobacilli during intestinal passage of the probiotic strain was non-detectable under the conditions tested, although transfer at low frequencies or to the remaining faecal bacterial population cannot be excluded.
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| 9. |
- Ejlertsson, Jörgen, et al.
(författare)
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Anaerobic degradation of xenobiotics by organisms from munical solid waste under landfilling conditions
- 1995
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - 0003-6072 .- 1572-9699. ; 69:1, s. 67-74
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Tidskriftsartikel (refereegranskat)abstract
- The potential for biological transformation of 23 xenobiotic compounds by microorganisms in municipal solid waste (MSW) samples from a laboratory scale landfill reactor was studied. In addition the influence of these xenobiotic compounds on methanogenesis was investigated. All R11, 1,1 dichloroethylene, 2,4,6 trichlorophenol, dimethyl phthalate, phenol, benzoate and phthalic acid added were completely transformed during the period of incubation (> 100 days). Parts of the initially added perchloroethylene, trichloroethylene, R12, R114, diethyl phthalate, dibutyl phthalate and benzylbutyl phthalate were transformed. Methanogenesis from acetate was completely inhibited in the presence of 2,5 dichlorophenol, whereas 2,4,6 trichlorophenol and R11 showed an initial inhibition, whenafter methane formation recovered. No transformation or effect on the anaerobic microflora occurred for R13, R22, R114, 3 chlorobenzoate, 2,4,6 trichlorobenzoate, bis(2 ethyl)hexyl phthalate, diisodecyl phthalate and dinonyl phthalate. The results indicate a limited potential for degradation, of the compounds tested, by microorganisms developing in a methanogenic landfill environment as compared with other anaerobic habitats such as sewage digestor sludge and sediments.
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| 10. |
- Erichsen, Inger, et al.
(författare)
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The microflora of semi-preserved fish products : II. The effect of the quality of raw materials, added materials, and storage conditions
- 1964
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - 0003-6072 .- 1572-9699. ; 30:1, s. 197-208
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This paper is concerned with titbits, i.e. canned fish products that have not been subjected to heat, but which have certain keeping qualities thanks to their high salt content, low pH, and the addition of preservatives. The effects of such factors as the raw material used, the composition of the pickle added to the titbits before they are canned, and physical procedures, e.g. freezing and thawing, on the keeping qualities of the titbits have been investigated. The keeping quality varied substantially with the amount of sugar added to the pickle, a high sugar content markedly prolonging and a low sugar content shortening the maximum tolerable duration of storage of the products. Sodium benzoate proved to have a good effect as a preservative, while nisin had no demonstrable antibiotic effect at all. Freezing of canned titbits before storage at 20 C produced some improvement in keeping qualities and seemed to damage some types of bacteria present. In fermented specimens of titbits the microflora was dominated by cocci and lactobacilli. However, the total amount of bacteria initially present in the cans is not directly correlated to the keeping qualities of the product. © 1964 Swets & Zeitlinger.
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| 11. |
- Erichsen, Inger
(författare)
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The microflora of semi-preserved fish products : III. Principal groups of bacteria occurring in titbits
- 1967
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - 0003-6072 .- 1572-9699. ; 33:1, s. 107-112
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial cultures isolated from semi-preserved fish products (i.e. titbits) and believed to be of major importance in the spoilage of the product, were examined and classified. Three groups were found. One group belonged to the family Micrococcaceae, containing strains from the genera Micrococcus and Staphylococcus. The remaining two groups belonged to the family Lactobacteriaceae, comprising two species of the genus Pediococcus and heterofermentative species of the genera Lactobacillus and Leuconostoc. © 1967 Swets & Zeitlinger.
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| 12. |
- Johansson, Anna H, et al.
(författare)
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Studies of plant colonisation by closely related Bacillus amyloliquefaciens biocontrol agents using strain specific quantitative PCR assays
- 2014
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 106, s. 1247-1257
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Tidskriftsartikel (refereegranskat)abstract
- Certain strains of Bacillus amyloliquefaciens can colonize plants and improve growth and stress management. In order to study these effects, bacterial growth dynamics on plants and in the rhizosphere are of interest calling for specific analytical tools. For that purpose, quantitative real-time PCR (qPCR) assays were developed in order to differentiate among three closely related B. amyloliquefaciens subsp. plantarum strains (UCMB5033, UCMB5036, UCMB5113) and to determine their levels with high accuracy. Oligonucleotide primers were designed for strain unique gene sequences and used for SYBR green based qPCR analysis. Standard curves covered a wide linear range (10(6)) of DNA amounts with the lowest detection level at 50 fg. Post-reaction melting curve analysis showed only a single product. Accurate threshold cycles were obtained, even in the presence of high excess of related Bacillus strains and total bacterial DNA from soil. Analysis of Bacillus colonisation after seed treatment of two oilseed rape cultivars (Oase and Ritz) grown on agar support showed a time dependent effect but that the bacteria mostly were found on root tissues and little on green tissues. The colonisation on plants grown in soil varied among the Bacillus strains where Oase seemed to house more bacteria than Ritz. Applied as a mixture, all three Bacillus strains co-existed on the roots of plants grown in soil. The qPCR assay in combination with other techniques will be a powerful tool to study plant interactions of these B. amyloliquefaciens biocontrol agents to further understand the requirements for successful interactions and improvement of plant properties.
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| 13. |
- Kayingo, G., et al.
(författare)
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Accumulation and release of the osmolyte glycerol is independent of the putative MIP channel Spac977.17p in Schizosaccharomyces pombe
- 2004
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Ingår i: Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology. - 0003-6072 .- 1572-9699. ; 85:2, s. 85-92
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Tidskriftsartikel (refereegranskat)abstract
- Schizosaccharomyces pombe accumulates glycerol as an osmotic regulatory solute in response to hyper-osmotic conditions. Upon a decrease in the external osmolarity, the intracellular glycerol levels should be adjusted in order to attain osmotic homeostasis. In this study, the patterns and kinetics of glycerol export from S. pombe were investigated. Upon a decrease in external osmolarity, glycerol was rapidly exported from cells to the external medium. The amount of glycerol released from the cells was proportional to the degree of change in the external osmolarity. The export process was well controlled and was not affected by reduced temperature. This points to S. pombe controlling glycerol export using specialized facilitating proteins as has been found in Saccharomyces cerevisiae where a MIP family channel protein Fps1p is involved. Analysis of the S. pombe databases revealed a putative transport protein (Spac977.17p) with homology to glycerol channel proteins of the MIP family. However, expression of the gene into the S. cerevisiae strain lacking a glycerol channel protein (fps1Delta mutant), did not complement the defect in glycerol export during hypo-osmotic stress. Deletion of spac977.17, did not affect glycerol accumulation or release in S. pombe. The patterns and kinetics of glycerol release in the mutant were similar to those of the wild type strains suggesting that the export process is independent of Spac977.17p, the only putative MIP family glycerol channel homologue in S. pombe. While the process of glycerol export in response to hypo-osmotic stress is similar to budding yeast, the underlying molecular mechanism in S. pombe appears distinct from that described in S. cerevisiae. Further studies are needed to elucidate the physiological role of the Spac977.17p channel.
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| 14. |
- Linder, Tomas
(författare)
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Genetic redundancy in the catabolism of methylated amines in the yeast Scheffersomyces stipitis
- 2018
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 111, s. 401-411
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Tidskriftsartikel (refereegranskat)abstract
- The catabolism of choline as a source of nitrogen in budding yeasts is thought to proceed via the intermediates trimethylamine, dimethylamine and methylamine before the release of ammonia. The present study investigated the utilisation of choline and its downstream intermediates as nitrogen sources in the yeast Scheffersomyces stipitis using a reverse genetics approach. Six genes (AMO1, AMO2, SFA1, FGH1, PICST_49761, PICST_63000) that have previously been predicted to be directly or indirectly involved in the catabolism of methylated amines were individually deleted. The growth of each deletion mutant was assayed on minimal media with methylamine, dimethylamine, trimethylamine or choline as the sole nitrogen source. The two amine oxidase-encoding genes AMO1 and AMO2 appeared to be functionally redundant for growth on methylated amines as both deletion mutants displayed growth on all nitrogen sources tested. However, deletion of AMO1 resulted in a pronounced growth lag on all four methylated amines while deletion of AMO2 only caused a growth lag when methylamine was the sole nitrogen source. The glutathione-dependent formaldehyde dehydrogenase-encoding gene SFA1 was found to be absolutely essential for growth on all methylated amines tested while deletion of the S-formylglutathione hydrolase gene FGH1 caused a pronounced growth lag on dimethylamine, trimethylamine and choline. The putative cytochrome P450 monooxygenase-encoding genes PICST_49761 and PICST_63000 were considered likely candidates for demethylation of di- and trimethylamine but produced no discernable phenotype on any of the tested nitrogen sources when deleted. This study revealed notable instances of genetic redundancies in the choline catabolic pathway, which are discussed.
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| 15. |
- Linder, Tomas
(författare)
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Nitrogen source-dependent inhibition of yeast growth by glycine and its N-methylated derivatives
- 2020
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 113, s. 437-445
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Tidskriftsartikel (refereegranskat)abstract
- The effect of nitrogen source on the inhibitory properties of glycine and its N-methylated derivatives N-methylglycine (sarcosine), N,N-dimethylglycine, N,N,N-trimethylglycine (glycine betaine) on yeast growth was investigated. On solid minimal medium, all four glycine species completely or partially inhibited growth of Kluyveromyces lactis, Komagataella pastoris, Ogataea arabinofermentans, Spathaspora passalidarum and Yamadazyma tenuis at concentrations 5-10 mM when 10 mM NH4Cl was the sole source of nitrogen. If NH4Cl was substituted by sodium L-glutamate as the sole source of nitrogen, obvious growth inhibition by glycine and its N-methylated derivatives was generally not observed in any of these species. No obvious growth inhibition by any of the glycine species at a concentration of 10 mM was observed in Cyberlindnera jadinii, Lipomyces starkeyi, Lodderomyces elongisporus, Scheffersomyces stipitis or Yarrowia lipolytica on solid minimal medium irrespective of whether the nitrogen source was NH4Cl or sodium L-glutamate. Growth inhibition assays of K. pastoris in liquid minimal medium supplemented with increasing concentrations of N,N-dimethylglycine demonstrated inhibitory effects for nine tested nitrogen sources. In most cases, N,N-dimethylglycine supplementation caused a decrease in growth efficiency that appeared to be proportional to the concentration of N,N-dimethylglycine. The biological relevance of these results is discussed.
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| 16. |
- Linder, Tomas
(författare)
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Utilisation of aromatic organosulfur compounds as sulfur sources by Lipomyces starkeyi CBS 1807
- 2016
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 109, s. 1417-1422
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Tidskriftsartikel (refereegranskat)abstract
- Aromatic organosulfur compounds that contain aryl carbon-sulfur bonds are rare in nature but occur frequently in industrial processes and products. The utilisation of aryl sulfur compounds as a sulfur source has not been described previously among the budding yeasts (phylum Ascomycota, sub-phylum Saccharomycotina). A total of 31 strains representing 30 species and 28 genera of the budding yeasts were assayed for utilisation of benzene sulfonate as source of sulfur. Lipomyces starkeyi CBS 1807 was the only strain in this screen that was able to utilise benzene sulfonate as a sulfur source. Further study of L. starkeyi demonstrated that it could also utilise methyl phenyl sulfoxide, 1-naphthalene sulfonate, 2-naphthalene sulfonate, 1-anthraquinone sulfonate and 2-anthraquinone sulfonate as sulfur sources but not diphenylsulfone. This study represents the first reported case of the utilisation of sulfonated naphthalenes and anthraquinones as sulfur sources by a fungus. However, it should be stressed that the remaining 30 strains in this study were not assayed for the utilisation of these additional aryl sulfur compounds as sulfur sources. The present study highlights the potential of L. starkeyi and related species as a source of novel enzyme activities with possible applications in chemical manufacturing, disposal of xenobiotics and bioremediation.
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| 17. |
- Lindh, Jenny M., et al.
(författare)
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The tsetse fly Glossina fuscipes fuscipes (Diptera: Glossina) harbours a surprising diversity of bacteria other than symbionts
- 2011
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 99:3, s. 711-720
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Tidskriftsartikel (refereegranskat)abstract
- Three different bacterial species are regularly described from tsetse flies. However, no broad screens have been performed to investigate the existence of other bacteria in this medically and agriculturally important vector insect. Utilising both culture dependent and independent methods we show that Kenyan populations of Glossina fuscipes fuscipes harbour a surprising diversity of bacteria. Bacteria were isolated from 72% of flies with 23 different bacterial species identified. The Firmicutes phylum dominated with 16 species of which seven belong to the genus Bacillus. The tsetse fly primary symbiont, Wigglesworthia glossinidia, was identified by the culture independent pathway. However, neither the secondary symbiont Sodalis nor Wolbachia was detected with either of the methods used. Two other bacterial species were identified with the DNA based method, Bacillus subtilis and Serratia marcescens. Further studies are needed to determine how tsetse flies, which only ever feed on vertebrate blood, pick up bacteria and to investigate the possible impact of these bacteria on Glossina longevity and vector competence.
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| 18. |
- Linninge, Caroline, et al.
(författare)
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Pre-treatment with antibiotics and Escherichia coli to equalize the gut microbiota in conventional mice.
- 2015
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 1572-9699 .- 0003-6072. ; 107:1, s. 149-156
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Tidskriftsartikel (refereegranskat)abstract
- The composition of the gut microbiota can vary widely between individual mice of the same batch and thereby affect the resulting outcome in experimental studies. Therefore, an efficient method is needed to equalize the gut microbiota prior to the start of critical experiments. In order to minimize variations in gut microbiota between animals and provide the animals with a Gram-negative flora exposing lipopolysaccharides in the cell-walls, C57BL/6 mice were given a mixture of ampicillin, metronidazole and clindamycin in the drinking water for 3 days and then Escherichia coli for two additional days. Treatment with antibiotics alone or with antibiotics in combination with E. coli was well tolerated by all animals. Body weight and liver weight were not affected, although higher hepatic fat content was found in treated animals (p < 0.05). The diversity of the gut microbiota was strongly reduced in animals treated with antibiotics and antibiotics in combination with E. coli (p < 0.01), without affecting the total amount of bacteria. Cloned and sequenced 16S rRNA genes showed high presence of Enterobacteriaceae and Porphymonadaceae in the treated animals. Analysis with Principal Component Analysis gave a clear separation of the composition in microbiota between different treatment groups. The described treatment efficiently equalized the gut microbiota and provided the animals with a strong abundance of Enterobacteriaceae without changing the total load of bacteria. This is a straightforward, lenient and efficient method of pre-treatment to equalize the gut microbiota of mice as a starting procedure of animal studies.
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| 19. |
- Medina-Silva, Renata, et al.
(författare)
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Microbiota associated with tubes of Escarpia sp. from cold seeps in the southwestern Atlantic Ocean constitutes a community distinct from that of surrounding marine sediment and water
- 2017
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 111:4, s. 533-550
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Tidskriftsartikel (refereegranskat)abstract
- As the depth increases and the light fades in oceanic cold seeps, a variety of chemosynthetic-based benthic communities arise. Previous assessments reported polychaete annelids belonging to the family Siboglinidae as part of the fauna at cold seeps, with the ‘Vestimentifera’ clade containing specialists that depend on microbial chemosynthetic endosymbionts for nutrition. Little information exists concerning the microbiota of the external portion of the vestimentiferan trunk wall. We employed 16S rDNA-based metabarcoding to describe the external microbiota of the chitin tubes from the vestimentiferan Escarpia collected from a chemosynthetic community in a cold seep area at the southwestern Atlantic Ocean. The most abundant operational taxonomic unit (OTU) belonged to the family Pirellulaceae (phylum Planctomycetes), and the second most abundant OTU belonged to the order Methylococcales (phylum Proteobacteria), composing an average of 21.1 and 15.4% of the total reads on tubes, respectively. These frequencies contrasted with those from the surrounding environment (sediment and water), where they represent no more than 0.1% of the total reads each. Moreover, some taxa with lower abundances were detected only in Escarpia tube walls. These data constitute on the first report of an epibiont microbial community found in close association with external surface of a cold-seep metazoan, Escarpia sp., from a chemosynthetic community in the southwestern Atlantic Ocean.
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| 20. |
- Melin, Petter, et al.
(författare)
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Formulation and stabilisation of the biocontrol yeast Pichia anomala
- 2011
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - Dordrecht, Netherlands : Springer Netherlands. - 0003-6072 .- 1572-9699. ; 99:1, s. 107-112
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Tidskriftsartikel (refereegranskat)abstract
- The yeast Pichia anomala has antifungal activities and its potential in biocontrol and biopreservation has previously been demonstrated. To practically use an organism in such applications on a larger scale the microbe has to be formulated and stabilised. In this review we give an overview of our experience of formulating and stabilising P. anomala strain J121 in a wider perspective. The stabilisation techniques we have evaluated were liquid formulations, fluidised bed drying, lyophilisation (freeze-drying) and vacuum drying. With all methods tested it was possible to obtain yeast cells with shelf lives of at least a few months and in all cases the biocontrol activity was retained. Fluidised bed drying was dependent on the addition of cottonseed flour as a carrier during the drying process. In liquid formulations a sugar, preferentially trehalose, was a required additive. These two kinds of microbial stabilisation are easily performed and relatively inexpensive but in order to keep the cells viable the biomaterial has to be stored at cool temperatures. However, there is room for optimization, such as improving the growth conditions, or include preconditioning steps to enable the cells to produce more compatible solutes necessary to survive formulation, desiccation and storage. In contrast, lyophilisation and vacuum drying require a lot of energy and are thus expensive. On the other hand, the dried cells were mostly intact after one year of storage at 30A degrees C. Inevitably, the choice of formulation and stabilisation techniques will be dependent also on the intended use.
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| 21. |
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| 22. |
- Olstorpe, Matilda, et al.
(författare)
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Pichia anomala in grain biopreservation
- 2011
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 99, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- Cereal grain is a major component of food and feed in large parts of the world. The microbial flora on cereal grains may interfere with hygiene and storage stability, palatability and bioavailability of minerals and proteins may depend on the composition of the microbial population. Therefore, it is of primary interest to control the microbial species present on cereal grain. Inoculation of the biocontrol yeast Pichia anomala to cereal feed grain improved feed hygiene by reduction of moulds and Enterobacteriaceae, and enhanced the nutritional value by increasing the protein content and reducing the concentration of the antinutritional compound phytate. P. anomala strains showed a high phytase activity, for some strains also considerable extracellular phytase activity was observed. A certain maximum in biomass concentration was never exceeded indicating cell density induced growth inhibition of P. anomala.
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| 23. |
- Osaku, Erica F., et al.
(författare)
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beta-(1 -> 6)-d-glucan secreted during the optimised production of exopolysaccharides by Paecilomyces variotii has immunostimulatory activity
- 2018
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - : Springer. - 0003-6072 .- 1572-9699. ; 111:6, s. 981-994
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Tidskriftsartikel (refereegranskat)abstract
- Paecilomyces variotii is a filamentous fungus that occurs worldwide in soil and decaying vegetation. Optimization of the fermentation process for exopolysaccharide (EPS) production from the fungus P. variotii, structure determination and immuno-stimulating activity of EPS were performed. Response surface methodology (RSM) coupled with central composite design (CCD) was used to optimize the physical and chemical factors required to produce EPS in submerged fermentation. Preliminary investigations to choose the three factors for the present work were made using a factorial experimental design. Glucose, ammonium nitrate (NH4NO3) and pH were used as variables for which, with constant temperature of 28 A degrees C and agitation of 90 rpm, the optimal process parameters were determined as glucose values of 0.96%, NH4NO3 0.26% and pH 8.0. The three parameters presented significant effects. In this condition of culture, the main composition of the isolated EPS was a linear beta-(1 -> 6)-linked-D-glucan, as determined by Nuclear Magnetic Resonance (NMR) and methylation analysis. This polysaccharide is a very unusual as an EPS from fungi, especially a filamentous fungus such as P. variotii. Murine peritoneal macrophages cultivated with beta-glucan for 6 and 48 h showed an increase in TNF-alpha, IL-6 and nitric oxide release with increased polysaccharide concentrations. Therefore, we conclude that the beta-(1 -> 6)-linked-D-glucan produced in optimised conditions of P. variotii cultivation has an immune-stimulatory activity on murine macrophages.
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| 24. |
- Passoth, Volkmar, et al.
(författare)
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Cryptococcus cerealis sp nov a psychrophilic yeast species isolated from fermented cereals
- 2009
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - Dordrecht, Netherlands : Springer. - 0003-6072 .- 1572-9699. ; 96:4, s. 635-643
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Tidskriftsartikel (refereegranskat)abstract
- Two yeast strains isolated in 2007 from fermented pig feed were studied, including the analysis of sequences of the D1/D2 and ITS-regions of the rDNA-repeats, their morphology and nutritional physiology. Sequence comparison of the D1/D2 and ITS regions demonstrated that the strains do not belong to any known species. Therefore, a new species, Cryptococcus cerealis with the type strain CBS 10505, is proposed. The species belongs to Filobasidiales (Agaricomycetes, Basidiomycota), and has Cryptococcus saitoi as the closest related species. The new species is psychrophilic, showing significant growth at 4 and 10A degrees C.
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| 25. |
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| 26. |
- Passoth, Volkmar, et al.
(författare)
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Past, present and future research directions with Pichia anomala
- 2011
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - Dordrecht, Netherlands : Springer. - 0003-6072 .- 1572-9699. ; 99:1, s. 121-125
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Tidskriftsartikel (refereegranskat)abstract
- The first International Pichia anomala Symposium provided a survey of past, recent and ongoing research on this yeast. The research community working with this yeast has focussed on several areas. Based on molecular data, a revision of the taxonomy is required: the name P. anomala is no longer applicable, as the genus Pichia is polyphyletic. The current debate centres on whether the yeast should be designated as Wickerhamomyces anomalus or if the previous name, Hansenula anomala, should be re-instated. The anti-microbial activities of this yeast received considerable attention during the symposium. H. anomala has been extensively studied as a biopreservation agent in many different post-harvest systems. Several mechanisms account for its anti-microbial activities, including the production of killer proteins and toxic volatile metabolites. Anti-idiotypic antibodies generating an "internal image" of a killer protein have been found to possess therapeutic activity against a broad range of microorganisms. A great diversity of H. anomala strains was reported at the symposium. Strains have been isolated from several food and feed systems and even from the intestine and reproductive organs of a malaria vector (Anopheles stephensi). Feed and food supplemented with certain H. anomala strains show an improved quality due, for example, to the addition of advantageous proteins and phytase activity. However, a number of apparent opportunistic pathogenic strains have also been isolated. Strain differentiation, especially the recognition of potentially pathogenic isolates, is an important challenge for the future commercialisation of this yeast. Future industrial and agricultural application of this yeast also raises questions of the economics of large-scale production, its survival during storage (formulation) and of safety regulations, all of which require further investigation.
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| 27. |
- Passoth, Volkmar
(författare)
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Physiology and gene expression profiles of Dekkera bruxellensis in response to carbon and nitrogen availability
- 2013
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 104, s. 855-868
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Tidskriftsartikel (refereegranskat)abstract
- The assimilation of nitrate, a nitrogenous compound, was previously described as an important factor favoring Dekkera bruxellensis in the competition with Saccharomyces cerevisiae for the industrial sugarcane substrate. In this substrate, nitrogen sources are limited and diverse, and a recent report showed that amino acids enable D. bruxellensis to grow anaerobically. Thus, understanding the regulation of nitrogen metabolism is one fundamental aspect to comprehend the competiveness of D. bruxellensis in the fermentation environment. In the present study, we evaluated the physiological and transcriptional profiles of D. bruxellensis in response to different carbon and nitrogen supplies to determine their influence on growth, sugar consumption, and ethanol production. Besides, the expression of genes coding for nitrogen permeases and enzymes involved in the biosynthesis of glutamate and energetic metabolism were investigated under these conditions. Our data revealed that genes related to nitrogen uptake in D. bruxellensis are under the control of nitrogen catabolite repression. Moreover, we provide indications that glutamate dehydrogenase and glutamate synthase may switch roles as the major pathway for glutamate biosynthesis in D. bruxellensis. Finally, our data showed that in nonoptimal growth conditions, D. bruxellensis leans toward the respiratory metabolism. The results presented herein show that D. bruxellensis and S. cerevisiae share similar regulation of GDH-GOGAT pathway, while D. bruxellensis converts less glucose to ethanol than S. cerevisiae do when nitrogen is limited. The consequence of this particularity to the industrial process is discussed.
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| 28. |
- Raghavendran, Vijayendran, 1976, et al.
(författare)
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A simple scaled down system to mimic the industrial production of first generation fuel ethanol in Brazil
- 2017
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Ingår i: Antonie van Leeuwenhoek, International Journal of General and Molecular Microbiology. - : Springer Science and Business Media LLC. - 1572-9699 .- 0003-6072. ; 110:7, s. 971-983
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Tidskriftsartikel (refereegranskat)abstract
- Although first-generation fuel ethanol is produced in Brazil from sugarcane-based raw materials with high efficiency, there is still little knowledge about the microbiology, the biochemistry and the molecular mechanisms prevalent in the non-aseptic fermentation environment. Learning-by-doing has hitherto been the strategy to improve the process so far, with further improvements requiring breakthrough technologies. Performing experiments at an industrial scale are often expensive, complicated to set up and difficult to reproduce. Thus, developing an appropriate scaled down system for this process has become a necessity. In this paper, we present the design and demonstration of a simple and effective laboratory-scale system mimicking the industrial process used for first generation (1G) fuel ethanol production in the Brazilian sugarcane mills. We benchmarked this system via the superior phenotype of the Saccharomyces cerevisiae PE-2 strain, compared to other strains from the same species: S288c, baker's yeast, and CEN.PK113-7D. We trust that such a system can be easily implemented in different laboratories worldwide, and will allow a better understanding of the S. cerevisiae strains that can persist and dominate in this industrial, non-aseptic and peculiar environment.
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| 29. |
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| 30. |
- Rönnander, Jonas, et al.
(författare)
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Growth of wood-inhabiting yeasts of the Faroe Islands in the presence of spent sulphite liquor
- 2021
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - : Springer. - 0003-6072 .- 1572-9699. ; 114, s. 649-666
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Tidskriftsartikel (refereegranskat)abstract
- In the microbial community of decaying wood, yeasts are important for the recycling of nutrients. Nevertheless, information on their biodiversity in this niche in the Northern hemisphere is limited. Wood-colonising yeasts encounter identical and similar growth-inhibitory compounds as those in spent sulphite liquor (SSL), an energy-rich, acid hydrolysate and waste product from the paper industry, which may render them well-suited for cultivation in SSL. In the present study, yeasts were isolated from decaying wood on the Faroe Islands and identified based on sequence homology of the ITS and D1/D2 regions. Among the yeasts isolated, Candida argentea, Cystofilobasidium infirmominiatum, Naganishia albidosimilis, Naganishia onofrii, Holtermanniella takashimae and Goffeauzyma gastrica were new to decaying wood in cold and temperate climates. C. argentea and Rhodotorula are rarely-isolated species, with no previous documentation from cold and maritime climates. The isolates were further tested for growth in a medium with increasing concentrations of softwood SSL. Most grew in the presence of 10% SSL. Isolates of Debaryomyces sp., C. argentea and Rhodotorula sp. were the most tolerant. Representatives of Debaryomyces and Rhodotorula have previously been found in decaying wood. In contrast, the least tolerant isolates belonged to species that are rarely reported from decaying wood. The relative importance of individual inhibitors to yeast growth is discussed. To our knowledge, none of the present yeast species have previously been cultivated in SSL medium. Decaying wood can be a useful future source of yeasts for valorisation of various hydrolysates to industrial chemicals and biofuels.
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| 31. |
- Schnürer, Johan, 1957-, et al.
(författare)
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Pichia anomala J121 : a 30-year overnight near success biopreservation story
- 2011
-
Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - Dordrecht, Netherlands : Springer Netherlands. - 0003-6072 .- 1572-9699. ; 99:1, s. 5-12
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Tidskriftsartikel (refereegranskat)abstract
- Thirty years ago, the ascomycetous yeast Pichia anomala strain J121 was isolated from moist wheat grain stored under conditions of restricted air access. Early observations indicated that an inverse relationship existed between mould and P. anomala colony forming units in grain. This yeast strain was later found to have strong antifungal properties in laboratory, pilot and farm studies with high-moisture wheat under malfunctioning airtight storage. P. anomala had the highest inhibitory activity of 60 yeast species evaluated against the mould Penicillium roqueforti. It also demonstrated strong inhibitory effects against certain Gram-negative bacteria. P. anomala J121 possesses a number of physiological characteristics, i.e. capacity to grow under low pH, low water activity and low oxygen tension and ability to use a wide range of carbon and nitrogen sources, enabling it to act as an efficient biopreservative agent. The biocontrol effect in grain was enhanced by addition of glucose, mainly through formation of the volatile antimicrobial ethyl acetate. Animal feeding trials with P. anomala J121 inoculated grains, fed to chickens and beef cattle, demonstrated that mould control observed in vitro in small scale laboratory experiments could be extended to large scale farm trials. In addition, no adverse effects on animal weight gain, feed conversion, health or behaviour were observed. We have now studied P. anomala J121 biology, ecology and grain preservation ability for 30 years. Over this period, more than 40 scientific publications and five PhD theses have been written on different aspects of this yeast strain, extending from fundamental research on metabolism, genetics and molecular biology, all the way to practical farm-scale level. In spite of the well documented biopreservative ability of the yeast, it has to date been very difficult to create the right constellation of technical, agricultural and biotechnical industries necessary to reach a commercial launch of a P. anomala J121 based biopreservation system. Additionally, the complications caused by a complex EU regulatory system remain a significant barrier to practical applications.
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| 32. |
- Singh, Bhupender, et al.
(författare)
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Growth, cell division and sporulation in mycobacteria
- 2010
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 98:2, s. 165-177
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Tidskriftsartikel (refereegranskat)abstract
- Bacteria have the ability to adapt to different growth conditions and to survive in various environments. They have also the capacity to enter into dormant states and some bacteria form spores when exposed to stresses such as starvation and oxygen deprivation. Sporulation has been demonstrated in a number of different bacteria but Mycobacterium spp. have been considered to be non-sporulating bacteria. We recently provided evidence that Mycobacterium marinum and likely also Mycobacterium bovis bacillus Calmette-Gu,rin can form spores. Mycobacterial spores were detected in old cultures and our findings suggest that sporulation might be an adaptation of lifestyle for mycobacteria under stress. Here we will discuss our current understanding of growth, cell division, and sporulation in mycobacteria.
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| 33. |
- Suarez, Rudy, et al.
(författare)
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Whole-Genome sequencing and comparative genomics of Mycobacterium spp. from farmed Atlantic and coho salmon in Chile
- 2021
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - : Springer. - 0003-6072 .- 1572-9699. ; 114:9, s. 1323-1336
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Tidskriftsartikel (refereegranskat)abstract
- Several members of the Mycobacterium genus cause invasive infections in humans and animals. According to a recent phylogenetic analysis, some strains of Mycobacterium salmoniphilum (Msal), which are the main culprit in bacterial outbreaks in freshwater fish aquaculture, have been assigned to a separate branch containing Mycobacterium franklinii (Mfra), another species that causes infections in humans. However, this genus is little studied in an aquaculture context. Here, we isolated four Mycobacterium spp. strains from freshwater cultures of Atlantic and coho salmon in Chile and performed whole-genome sequencing for deep genomic characterization. In addition, we described the gross pathology and histopathology of the outbreaks. Several bioinformatic analyses were performed using the genomes of these four Mycobacterium isolates in conjunction with those of Msal strains, four Msal-like strains, and one Mfra strains, plus 17 other publicly available Mycobacterium genomes. We found that three isolates are clustered into the Msal branch, whereas one isolate clustered with the Mfra/Msal-like strains. We further evaluated the presence of virulence and antimicrobial resistance genes and observed that the four isolates were closely related to the Msal and Msal-like taxa and carried several antimicrobial resistance and virulence genes that are similar to those of other pathogenic members of the Mycobacterium clade. Altogether, our characterization Msal and Msal-like presented here shed new light on the basis of mycobacteriosis provides quantitative evidence that Mycobacterium strains are a potential risk for aquaculture asetiological agents of emerging diseases, and highlight their biological scopes in the aquaculture industry.
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| 34. |
- Sundh, Ingvar, et al.
(författare)
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Safety and regulation of yeasts used for biocontrol or biopreservation in the food or feed chain
- 2011
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Ingår i: Antonie van Leeuwenhoek. - : Springer Science and Business Media LLC. - 0003-6072 .- 1572-9699. ; 99, s. 113-119
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Tidskriftsartikel (refereegranskat)abstract
- Yeasts have been important components of spontaneous fermentations in food and beverage processing for millennia. More recently, the potential of utilising antagonistic yeasts, e.g. Pichia anomala and Candida spp., for post-harvest biological control of spoilage fungi during storage of plant-derived produce ('biopreservation') has been clearly demonstrated. Although some yeast species are among the safest microorganisms known, several have been reported in opportunistic infections in humans, including P. anomala and bakers' yeast, Saccharomyces cerevisiae. More research is needed about the dominant pathogenicity and virulence factors in opportunistic yeasts, and whether increased utilisation of biopreservative yeasts in general could contribute to an increased prevalence of yeast infections. The regulatory situation for yeasts used in post-harvest biocontrol is complex and the few products that have reached the market are mainly registered as biological pesticides. The qualified presumption of safety (QPS) approach to safety assessments of microorganisms intentionally added to food or feed, recently launched by the European Food Safety Authority, can lead to more efficient evaluations of new products containing microbial species with a sufficient body of knowledge or long-term experience on their safety. P. anomala is one of several yeast species that have been given QPS status, although the status is restricted to use of this yeast for enzyme and metabolite production purposes. With regard to authorisation of new biopreservative yeasts, we recommend that the possibility to regulate microorganisms for food biopreservation as food additives be considered.
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| 35. |
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| 36. |
- Tandhyka Gemiarto, Adrian, et al.
(författare)
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Isoprenyl caffeate, a major compound in manuka propolis, is a quorum-sensing inhibitor in Chromobacterium violaceum
- 2015
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - : Kluwer Academic Publishers. - 0003-6072 .- 1572-9699. ; 108:2, s. 491-504
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Tidskriftsartikel (refereegranskat)abstract
- The emergence of antibiotic-resistant bacterial pathogens, especially Gram-negative bacteria, has driven investigations into suppressing bacterial virulence via quorum sensing (QS) inhibition strategies instead of bactericidal and bacteriostatic approaches. Here, we investigated several bee products for potential compound(s) that exhibit significant QS inhibitory (QSI) properties at the phenotypic and molecular levels in Chromobacterium violaceum ATCC 12472 as a model organism. Manuka propolis produced the strongest violacein inhibition on C. violaceum lawn agar, while bee pollen had no detectable QSI activity and honey had bactericidal activity. Fractionated manuka propolis (pooled fraction 5 or PF5) exhibited the largest violacein inhibition zone (24.5 ± 2.5 mm) at 1 mg dry weight per disc. In C. violaceum liquid cultures, at least 450 µg/ml of manuka propolis PF5 completely inhibited violacein production. Gene expression studies of the vioABCDE operon, involved in violacein biosynthesis, showed significant (≥two-fold) down-regulation of vioA, vioD and vioE in response to manuka propolis PF5. A potential QSI compound identified in manuka propolis PF5 is a hydroxycinnamic acid-derivative, isoprenyl caffeate, with a [M-H] of 247. Complete violacein inhibition in C. violaceum liquid cultures was achieved with at least 50 µg/ml of commercial isoprenyl caffeate. In silico docking experiments suggest that isoprenyl caffeate may act as an inhibitor of the violacein biosynthetic pathway by acting as a competitor for the FAD-binding pockets of VioD and VioA. Further studies on these compounds are warranted toward the development of anti-pathogenic drugs as adjuvants to conventional antibiotic treatments, especially in antibiotic-resistant bacterial infections.
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| 37. |
- Whitehead, T. R., et al.
(författare)
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Savagea faecisuis gen. nov., sp nov., a tylosin- and tetracycline-resistant bacterium isolated from a swine-manure storage pit
- 2015
-
Ingår i: Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology. - : Springer Science and Business Media LLC. - 0003-6072. ; 108:1, s. 151-161
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Tidskriftsartikel (refereegranskat)abstract
- A polyphasic taxonomic study using morphological, biochemical, chemotaxonomic and molecular methods was performed on three strains of a Gram-stain positive, non-sporeforming, motile aerobic rod-shaped bacterium resistant to tylosin and tetracycline isolated from a swine-manure storage pit. On the basis of 16S rRNA gene sequence analyses, it was confirmed that these isolates are highly related to each other and form a hitherto unknown lineage within the Planococcaceae. In particular, pairwise analysis of the 16S rRNA gene sequence demonstrated that the novel organism is closely related to members of the genus Sporosarcina (92.8-94.5 %), Pyschrobacillus (93.5-93.9 %) and Paenisporosarcina (93.3-94.5 %). The predominant fatty acids were found to consist of iso-C-15:0 and iso-C-17:1 omega 10c and the G+C mol% was determined to be 41.8. Based on biochemical, chemotaxonomic, and phylogenetic evidence, it is proposed that these novel strains be classified as a novel genus and species, Savagea faecisuis gen nov., sp. nov. The type strain is Con12(T) (=CCUG 63563(T) = NRRL B-59945(T) = NBRC 109956(T)).
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| 38. |
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| 39. |
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