| 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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