| 1. |
- Bukowska-Faniband, Ewa, et al.
(author)
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Cortex synthesis during Bacillus subtilis sporulation depends on the transpeptidase activity of SpoVD.
- 2013
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In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 346:1, s. 65-72
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Journal article (peer-reviewed)abstract
- The nonessential process of peptidoglycan synthesis during Bacillus subtilis sporulation is one model to study bacterial cell wall biogenesis. SpoVD is a class B high-molecular weight penicillin-binding protein that is specific for sporulation. Strains lacking this protein produce spores without the peptidoglycan cortex layer and are heat-sensitive. The detailed functions of the four different protein domains of the SpoVD protein are unknown and the observed phenotype of strains lacking the entire protein could be an indirect defect. We therefore inactivated the transpeptidase domain by substitution of the active site serine residue. Our results demonstrate that endospore cortex synthesis depends on the transpeptidase activity of SpoVD specifically. This article is protected by copyright. All rights reserved.
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| 2. |
- Cousin, C., et al.
(author)
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Protein-serine/threonine/tyrosine kinases in bacterial signaling and regulation
- 2013
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 346:1, s. 11-19
-
Research review (peer-reviewed)abstract
- In this review, we address some recent developments in the field of bacterial protein phosphorylation, focusing specifically on serine/threonine and tyrosine kinases. We present an overview of recent studies outlining the scope of physiological processes that are regulated by phosphorylation, ranging from cell cycle, growth, cell morphology, to metabolism, developmental phenomena, and virulence. Specific emphasis is placed on Mycobacterium tuberculosis as a showcase organism for serine/threonine kinases, and Bacillus subtilis to illustrate the importance of protein phosphorylation in developmental processes. We argue that bacterial serine/threonine and tyrosine kinases have a distinctive feature of phosphorylating multiple substrates and might thus represent integration nodes in the signaling network. Some open questions regarding the evolutionary benefits of relaxed substrate selectivity of these kinases are treated, as well as the notion of nonfunctional background' phosphorylation of cellular proteins. We also argue that phosphorylation events for which an immediate regulatory effect is not clearly established should not be dismissed as unimportant, as they may have a role in cross-talk with other post-translational modifications. Finally, recently developed methods for studying protein phosphorylation networks in bacteria are briefly discussed.
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| 3. |
- Patel, Ami, et al.
(author)
-
Evidence for xylooligosaccharides utilization in Weissella strains isolated from Indian fermented foods and vegetables.
- 2013
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 346:1, s. 20-28
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Journal article (other academic/artistic)abstract
- Six strains isolated from fermented food were by 16S rDNA sequencing identified as Weissella species, clustering with the species-pair W. confusa/ W. cibaria. The strains were analysed for growth on glucose, xylose and xylooligosaccharides (XOS). All strains were xylose positive using the API CHL 50 test. Growth on XOS was observed for strain 85, 92, 145 and AV1, firstly by optical density measurements in microtiter plates and secondly in batch cultures also confirming concomitant decrease in pH. Analysis of XOS before and after growth established consumption in the DP2 - DP5 range in the four XOS-fermenting strains. XOS were consumed simultaneously with glucose, while xylose was consumed after glucose depletion. Cell-associated β-xylosidase activity was detected in the XOS fermenting strains. Analysis of genomic data suggests this activity to be linked to genes encoding glycoside hydrolases from family 3, 8 or 43. No endo-β-xylanase activity was detectable. Main fermentation end products were lactate and acetate. A higher ratio of acetic acid/lactic acid was produced during growth on XOS compared to growth on glucose. This is the first report on utilization of XOS in Weissella, indicating an increased probiotic potential for XOS-utilizing strains from the species pair W. confusa/ W. cibaria, but also showing that XOS utilization is strain-dependent for these species. This article is protected by copyright. All rights reserved.
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| 4. |
- Persson, Jessica, et al.
(author)
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Molecular and cytological analysis of the expression of Streptomyces sporulation regulatory gene whiH.
- 2013
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 341:2, s. 96-105
-
Journal article (peer-reviewed)abstract
- The whiH gene is required for the orderly sporulation septation that divides aerial hyphae into spores in Streptomyces coelicolor. Here, we use a whiHp-mCherry transcriptional reporter construct to show that whiHp is active specifically in aerial hyphae, fluorescence being dependent on sporulation sigma factor WhiG. The results show that the promoter is active before the septation event that separates the sub-apical compartment from the tip compartment destined to become a spore chain. We conclude that WhiG-directed RNA polymerase activity, which is required for whiH transcription, must precede this septation event and is not restricted to apical sporogenic compartment of the aerial hyphae. Further, it is demonstrated that WhiH, a predicted member of the GntR family of transcription factors, is able to bind specifically to a sequence in its own promoter, strongly suggesting that it acts as an autoregulatory transcription factor. Finally, we show by site-directed mutagenesis and a genetic complementation test that whiH is translated from a start codon overlapping with the previously identified transcription start point, implying leaderless transcription.
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| 5. |
- Prosser, J. I., et al.
(author)
-
Most influential FEMS publications
- 2014
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 354:2, s. 83-84
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Journal article (other academic/artistic)
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| 6. |
- Ahrén, Dag, et al.
(author)
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Phylogeny of nematode-trapping fungi based on 18S rDNA sequences
- 1998
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In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 158:2, s. 179-184
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Journal article (peer-reviewed)abstract
- The small subunit (SSU) ribosomal DNA (18S rDNA) from 15 species of nematode-trapping fungi and closely related non-parasitic species were sequenced. Phylogenetic analysis indicated that species within the genera of Arthrobotrys, Dactylaria, Dactylella, Monacrosporium and Duddingtonia formed a monophyletic and isolated clade among an unresolved cluster of apothecial ascomycetes. The phylogenetic patterns within this clade were not concordant with the morphology of the conidia nor the conidiophores, but rather with that of the infection structures. The results from the different methods of tree reconstruction supported three lineages; the species having constricting rings, the non-parasitic species and the species having various adhesive structures (nets, hyphae, knobs and non-constricting rings) to infect nematodes.
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| 7. |
- Ambalam, Padma, et al.
(author)
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Bile stimulates Cell Surface Hydrophobicity, Congo Red Binding and Biofilm Formation of Lactobacillus strains.
- 2012
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 333:1, s. 10-19
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Journal article (peer-reviewed)abstract
- Seventeen Lactobacillus strains were tested for cell surface hydrophobicity (CSH) using the salt aggregation test (SAT) and Congo red binding (CRB) assay. CRB was pH and ionic strength dependent and protease sensitive and in the presence of 100 μg/ml cholesterol, the CRB was significantly reduced. Autoaggregating (AA) L. crispatus strains showed 50% more CRB than the reference strain, the curli-producing E.coli MC4100. CRB of L. crispatus 12005, L. paracasei F8, L. plantarum F44 and L. paracasei F19 was enhanced when grown in MRS broth with 0.5% taurocholic acid (TA) or 5% porcine bile (PB) (P<0.05). CSH was also enhanced for the non-AA strains, L. plantarum F44, L. paracasei F19 and L. rhamnosus GG when grown in MRS broth with 0.5% TA, 5% PB or 0.25% mucin with enhanced biofilm formation in MRS broth with bile (P<0.05). Two AA strains, L. crispatus 12005 and L. paracasei F8, developed biofilm independent of bile or mucin. In summary, under bile stressed growth conditions, early (24 h cultures) biofilm formation is associated with an increase in hydrophobic cell surface proteins and high CRB. Late mature (72 h culture) biofilm contained more carbohydrates as shown by crystal violet staining. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd.All rights reserved.
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| 8. |
- Baureder, Michael, et al.
(author)
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Contribution of catalase to hydrogen peroxide resistance in Enterococcus faecalis.
- 2012
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In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 331:2, s. 160-164
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Journal article (other academic/artistic)abstract
- Enterococcus faecalis exhibits high resistance to oxidative stress. Several enzymes are responsible for this trait. The role of alkyl hydroperoxide reductase (Ahp), thiol peroxidase (Tpx), and NADH peroxidase (Npr) in oxidative stress defense was recently characterized. Enterococcus faecalis, in contrast to many other streptococci, contains a catalase (KatA), but this enzyme can only be formed when the bacterium is supplied with heme. We have used this heme dependency of catalase activity and mutants deficient in KatA and Npr to investigate the role of the catalase in resistance against exogenous and endogenous hydrogen peroxide stress. The results demonstrate that in the presence of environmental heme catalase contributes to the protection against toxic effects of hydrogen peroxide.
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| 9. |
- Bielen, Abraham A. M., et al.
(author)
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Pyrophosphate as a central energy carrier in the hydrogen-producing extremely thermophilic Caldicellulosiruptor saccharolyticus
- 2010
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 307:1, s. 48-54
-
Journal article (peer-reviewed)abstract
- The role of inorganic pyrophosphate (PPi) as an energy carrier in the central metabolism of the extremely thermophilic bacterium Caldicellulosiruptor saccharolyticus was investigated. In agreement with its annotated genome sequence, cell extracts were shown to exhibit PPi-dependent phosphofructokinase and pyruvate phosphate dikinase activity. In addition, membrane-bound pyrophosphatase activity was demonstrated, while no significant cytosolic pyrophosphatase activity was detected. During the exponential growth phase, high PPi levels (approximately 4 +/- 2 mM) and relatively low ATP levels (0.43 +/- 0.07 mM) were found, and the PPi/ATP ratio decreased 13-fold when the cells entered the stationary phase. Pyruvate kinase activity appeared to be allosterically affected by PPi. Altogether, these findings suggest an important role for PPi in the central energy metabolism of C. saccharolyticus.
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| 10. |
- Bos, R., et al.
(author)
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Retention of bacteria on a substratum surface with micro-patterned hydrophobicity
- 2000
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 189:2, s. 311-315
-
Journal article (peer-reviewed)abstract
- Bacteria adhere to almost any surface, despite continuing arguments about the importance of physico-chemical properties of substratum surfaces, such as hydrophobicity and charge in biofilm formation. Nevertheless, in vivo biofilm formation on teeth and also on voice prostheses in laryngectomized patients is less on hydrophobic than on hydrophilic surfaces. With the aid of micro-patterned surfaces consisting of 10-mu m wide hydrophobic lines separated by 20-mu m wide hydrophilic spacings, we demonstrate here, For the first time in one and the same experiment, that bacteria do not have a strong preference for adhesion to hydrophobic or hydrophilic surfaces. Upon challenging the adhering bacteria, after deposition in a parallel plate flow chamber, with a high detachment force, however, bacteria were easily wiped-off hydrophobic lines, most notably when these lines were oriented parallel to the direction of flow. Adhering bacteria detached slightly less from the hydrophilic spacings in between, but preferentially accumulated adhering on the hydrophilic regions close to the interface between the hydrophilic spacings and hydrophobic lines. It is concluded that substratum hydrophobicity is a major determinant of bacterial retention while it hardly influences bacterial adhesion.
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| 11. |
- Carlsson, Peter, et al.
(author)
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In vitro complementation of Bacillus subtilis and Escherichia coli 2-oxoglutarate dehydrogenase complex mutants and genetic mapping of B. subtilis citK and citM mutations
- 1986
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 37:3, s. 373-378
-
Journal article (peer-reviewed)abstract
- AbstractThe 2-oxoglutarate dehydrogenase complex of the tricarboxylic acid cycle (TCA) consists of multiple copies of 3 different subenzymes; E1, E2 and E3. The E3 subenzyme is also a component of the pyruvate dehydrogenase complex. Bacillus subtilis 2-oxoglutarate dehydrogenase mutants were studied. The mutants defective in E1, E2 and E3 subenzyme activity, respectively, could be separated into 3 groups by biochemical complementation analyses. The groups correspond to the citK, citM and citL genes. A B. subtilis subenzyme defect, probably E1, could be complemented with the corresponding Escherichia coli wild-type subenzyme and vice versa. Mutations in citK and citM are closely linked. The gene order kauA--- ---citK-citM was determined from 3-factor transformation crosses. It is concluded that the gene organization and the subenzyme structure of the 2-oxoglutarate dehydrogenase complex are similar in B. subtilis and E. coli.
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| 12. |
- Chalot, Michel, et al.
(author)
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Respiration of [C-14] alanine by the ectomycorrhizal fungus Paxillus involutus
- 1994
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In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 121:1, s. 87-91
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Journal article (peer-reviewed)abstract
- The ectomycorrhizal fungus Paxillus involutus efficiently took up exogenously supplied [C-14]alanine and rapidly converted it to pyruvate, citrate, succinate, fumarate and to CO2, thus providing direct evidence for the utilisation of alanine as a respiratory substrate. [C-14]alanine was further actively metabolised to glutamate, glutamine and aspartate. Exposure to aminooxyacetate completely suppressed (CO2)-C-14 evolution and greatly reduced the flow of carbon from [C-14]alanine to tricarboxylic acid cycle intermediates and amino acids, suggesting that alanine aminotransferase plays a pivotal role in alanine metabolism in Paxillus involutus.
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| 13. |
- Fridén, H, et al.
(author)
-
Deletion of the Bacillus subtilis sdh operon
- 1987
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In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 41:2, s. 206-206
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Journal article (peer-reviewed)abstract
- Plasmid pKIM2 carries the Bacillus subtilis sdh operon and adjacent regions of the bacterial chromosome. The plasmid replicates in Escherichia coli but not in B. subtilis. Different portions of the sdh operon were removed from pKIM2 and replaced by a cat gene derived from pC194. A series of plasmids carrying sdh deletions was thus derived. Plasmid DNA was linearized at restriction sites within the vector part and used to transform B. subtilis to chloramphenicol resistance. The majority of the transformants had a succinate dehydrogenase-negative phenotype and were deleted in the sdh operon as verified by Southern blotting. The B. subtilis deletion mutants were used to determine the functional integrity of cloned sdh genes.
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| 14. |
- Hansson, Mats, et al.
(author)
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Heme b (protoheme IX) is a precursor of heme a and heme d in Bacillus subtilis
- 1993
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 107:1, s. 121-126
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Journal article (peer-reviewed)abstract
- Bacillus subtilis can synthesise cytochromes containing a-, b-, c- and d-type heme. The biosynthetic pathways of these heme prosthetic groups were investigated by using strains blocked in uroporphyrinogen III synthesis from porphobilinogen or in heme b (protoheme IX) synthesis from uroporphyrinogen III. The results strongly suggest that heme a and heme d are both synthesised from heme b (protoheme IX). They also indicate that B. subtilis contains a novel ferrochelatase involved in the synthesis of siroheme
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| 15. |
- Hulting, Greta, et al.
(author)
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Two novel IgG endopeptidases of Streptococcus equi
- 2009
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 298:1, s. 44-50
-
Journal article (peer-reviewed)abstract
- Streptococcus equi ssp. equi causes strangles, a highly contagious and serious disease in the upper respiratory tract of horses. Streptococcus equi ssp. zooepidemicus, another subspecies of this genus, is regarded as an opportunistic commensal in horses. The present study describes the characterization of two novel immunoglobulin G (IgG) endopeptidases of these subspecies, IdeE2 and IdeZ2. Both enzymes display sequence similarities with two previously characterized IgG endopeptidases, IdeE of S. equi ssp. equi and IdeZ of S. equi ssp. zooepidemicus. IdeE2 and IdeZ2 display high substrate-specificity in comparison with IdeE and IdeZ, as they both completely cleave horse IgG, while the activity against IgG from mouse, rabbit, cat, cow, sheep and goat is low or absent. The potential use of IdeE and IdeE2 as vaccine components was studied in a mouse infection model. In this vaccination and challenge study, both enzymes induced protection against S. equi ssp. equi infection.
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| 16. |
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| 17. |
- Karlsson, Fredrik, et al.
(author)
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Escherichia coli TolA tolerates multiple amino-acid substitutions as revealed by screening randomized variants for membrane integrity and phage receptor function
- 2006
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 259:1, s. 81-88
-
Journal article (peer-reviewed)abstract
- Escherichia coli TolA is a cytoplasmic membrane protein required for outer membrane integrity and the translocation of F-specific filamentous (Ff) bacteriophage DNA. Both phage infection and membrane integrity depend on several TolA interactions, e.g. those of the TolA C-terminal domain (TolAIII). Membrane integrity involves interaction with two host proteins and phage translocation requires direct interaction with the N-terminal domain (N1) of Ff phage protein g3p. Although cocrystallization of TolAIII and N1g3p has identified several contact points, it is still uncertain which residues are selectively involved in the different TolA functions. Thus, four different limited substitution libraries of TolA were created, targeting contacts at positions 415-420. These libraries were introduced into the tolA strain K17DE3tolA/F+ and several variants, containing complementing, multiple amino-acid substitutions, were identified. However, most randomized variants did not complement the tolA strain K17DE3tolA/F+. The TolA variants that restored sensitivity to phage infection displayed a considerable sequence variation, while the few variants that restored tolerance to detergent were from the same library. A comparison of the generated residue variation and natural variation, suggests that structural dependence overrides contact residue dependence. Thus, library screening can be efficient in identifying TolA variants with different functionally associated characteristics.
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| 18. |
- Letek, Michal, et al.
(author)
-
DivIVA uses an N-terminal conserved region and two coiled-coil domains to localize and sustain the polar growth in Corynebacterium glutamicum
- 2009
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 297:1, s. 110-116
-
Journal article (peer-reviewed)abstract
- Corynebacterium glutamicum is a rod-shaped actinomycete with a distinct model of peptidoglycan synthesis during cell elongation, which takes place at the cell poles and is sustained by the essential protein DivIVA(CG) (C. glutamicum DivIVA). This protein contains a short conserved N-terminal domain and two coiled-coil regions: CC1 and CC2. Domain deletions and chimeric versions of DivIVA were used to functionally characterize the three domains, and all three were found to be essential for proper DivIVA(CG) function. However, in the presence of the N-terminal domain from DivIVA(CG), either of the two coiled-coil domains of DivIVA(CG) could be replaced by the equivalent coiled-coil domain of Bacillus subtilis DivIVA (DivIVA(BS)) without affecting the function of the original DivIVA(CG), and more than one domain had to be exchanged to lose function. Although no single domain was sufficient for subcellular localization or function, CC1 was mainly implicated in stimulating polar growth and CC2 in targeting to DivIVA(CG) assemblies at the cell poles in C. glutamicum.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
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| 23. |
- Throne-Holst, Mimmi, et al.
(author)
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The Bacillus subtilis ctaB paralogue, yjdK, can complement the heme A synthesis deficiency of a CtaB-deficient mutant
- 2000
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 183, s. 247-251
-
Journal article (peer-reviewed)abstract
- Heme A is a prosthetic group in many respiratory oxidases. It is synthesised from heme B (protoheme IX) with heme O as an intermediate. In Bacillus subtilis two genes required for heme A synthesis, ctaA and ctaB, have been identified. CtaB is the heme O synthase and CtaA is involved in the conversion of heme O to heme A. A ctaB paralogue, yjdK, has been identified through the B. subtilis genome sequencing project. In this study we show that when carried on a low copy number plasmid, the yjdK gene can complement a ctaB deletion mutant with respect to heme A synthesis. Our results indicate that YjdK has heme O synthase activity. We therefore suggest that yjdK be renamed as ctaO.
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| 24. |
- Tinta, Tinkara, et al.
(author)
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Deoxyribonucleoside kinases in two aquatic bacteria with high specificity for thymidine and deoxyadenosine.
- 2012
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 331:2, s. 120-127
-
Journal article (peer-reviewed)abstract
- Deoxyribonucleoside kinases (dNKs) are essential in the mammalian cell but their 'importance' in bacteria, especially aquatic ones, is less clear. We studied two aquatic bacteria, Gram-negative Flavobacterium psychrophilum JIP02/86 and Polaribacter sp. MED152, for their ability to salvage deoxyribonucleosides (dNs). Both had a Gram-positive-type thymidine kinase (TK1), which could phosphorylate thymidine, and one non-TK1 dNK, which could efficiently phosphorylate deoxyadenosine and slightly also deoxycytosine. Surprisingly, the four tested dNKs could not phosphorylate deoxyguanosine, and apparently, these two bacteria are missing this activity. When tens of available aquatic bacteria genomes were examined for the presence of dNKs, a majority had at least a TK1-like gene, but several lacked any dNKs. Apparently, among aquatic bacteria, the role of the dN salvage varies.
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| 25. |
- Wang, Sheng-Bing, et al.
(author)
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Domains involved in the in vivo function and oligomerization of apical growth determinant DivIVA in Streptomyces coelicolor
- 2009
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 297:1, s. 101-109
-
Journal article (peer-reviewed)abstract
- The coiled-coil protein DivIVA is a determinant of apical growth and hyphal branching in Streptomyces coelicolor. We have investigated the properties of this protein and the involvement of different domains in its essential function and subcellular targeting. In S. coelicolor cell extracts, DivIVA was present as large oligomeric complexes that were not strongly membrane associated. The purified protein could self-assemble into extensive protein filaments in vitro. Two large and conspicuous segments in the amino acid sequence of streptomycete DivIVAs not present in other homologs, an internal PQG-rich segment and a carboxy-terminal extension, are shown to be dispensable for the essential function in S. coelicolor. Instead, the highly conserved amino-terminal of 22 amino acids was required and affected establishment of new DivIVA foci and hyphal branches, and an essential coiled-coil domain affected oligomerization of the protein.
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| 26. |
- GHIACI, PAYAM, 1982, et al.
(author)
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Production of 2-butanol through meso-2,3-butanediol consumption in lactic acid bacteria
- 2014
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 360:1, s. 70-75
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Journal article (other academic/artistic)abstract
- 2-Butanol has been an issue of industries in many areas, for example, biofuel production (as an advanced alternate fuel), fermented beverages, and food (as taste-altering component). Thus, its source of production, the biological pathway, and the enzymes involved are of high interest. In this study, 42 different isolates of lactic acid bacteria from nine different species were screened for their capability to consume meso-2,3-butanediol and produce 2-butanol. Lactobacillus brevis was the only species that showed any production of 2-butanol. Five of ten tested isolates of L.brevis were able to convert meso-2,3-butanediol to 2-butanol in a synthetic medium (SM2). However, none of them showed the same capability in a complex medium such as MRS indicating that the ability to produce 2-butanol is subject to some kind of repression mechanism. Furthermore, by evaluating the performance of the enzymes required to convert meso-2,3-butanediol to 2-butanol, that is, the secondary alcohol dehydrogenase and the diol dehydratase, it was shown that the latter needed the presence of a substrate to be expressed.
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| 27. |
- Jonsson, Hans
(author)
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Segmented filamentous bacteria in human ileostomy samples after high-fiber intake
- 2013
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 342, s. 24-29
-
Journal article (peer-reviewed)abstract
- Segmented filamentous bacteria (SFB) are inhabitants of the small intestine of various animals, where they can be detected microscopically due to their specific morphology and intimate association with the intestinal epithelium. SFB colonize the distal part of the small intestine in a host-specific manner and affects important functions of the immune system, such as the induction of secretory IgA production and regulation of T-cell maturation. Considering the influences SFB have on immune functions, they could be regarded as a key species in hostmicrobial interactions of the gastrointestinal tract. Although these influences might be executed by other microorganisms, a human-adapted variant of SFB is not unlikely. In this study, ileostomy samples from 10 human subjects were screened with PCR, using primers derived from sequences of SFB from rat and mouse. PCR products were obtained from samples taken from one individual at two time points. Sequencing revealed the presence of a 16S rRNA gene with high similarity (98%) to the corresponding genes from SFB of mouse and rat origin, thus indicating the presence of a human variant of SFB. The findings presented in this study will hopefully encourage research to elucidate whether this intriguing organism is a persistent member of the normal human microbiota.
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| 28. |
- Pettersson, B. M. Fredrik, et al.
(author)
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Identification and expression of stressosomal proteins in Mycobacterium marinum under various growth and stress conditions
- 2013
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 342:2, s. 98-105
-
Journal article (peer-reviewed)abstract
- Like other bacteria, Mycobacterium spp. have developed different strategies in response to environmental changes such as nutrient limitations and other different stress situations. We have identified candidate genes (rsb genes) from Mycobacterium marinum involved in the regulation of the activity of the alternative sigma factor, sigma F. This is a homolog of the master regulator of general stress response, sigma B, and the sporulation-specific sigma factor, sigma F, in Bacillus subtilis. The organization of these genes in M.marinum and B.subtilis is similar. Transcriptome and qRT-PCR data show that these genes are indeed expressed in M.marinum and that the levels of expression vary with growth phase and exposure to stress. In particular, cold stress caused a significant rise in the expression of all identified rsb and sigF genes. We discuss these data in relation to what is currently known for other Mycobacterium spp.
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| 29. |
- Sellstedt, Anita, et al.
(author)
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Aspects of nitrogen-fixing Actinobacteria, in particular free-living and symbiotic Frankia
- 2013
-
In: FEMS Microbiology Letters. - : Blackwell Publishing. - 0378-1097 .- 1574-6968. ; 342:2, s. 179-186
-
Research review (peer-reviewed)abstract
- Studies of nitrogen-fixing properties among the Gram-positive Actinobacteria revealed that some species of Arthrobacter, Agromyces, Corynebacterium, Mycobacterium, Micromonospora, Propionibacteria and Streptomyces have nitrogen-fixing capacity. This is also valid for Frankia that fix nitrogen both in free-living and in symbiotic conditions. Frankia symbiosis results from interaction between the Frankia bacteria and dicotyledonous plants, that is, actinorhiza. These plants, which are important in forestry and agroforestry, form, together with the legumes (Fabales), a single nitrogen-fixing clade. It has been shown that a receptor-like kinase gene, SymRK, is necessary for nodulation in actinorhizal plants as well as in legumes and arbuscular mycorrhizal fungi. Recently, the involvement of isoflavonoids as signal molecules during nodulation of an actinorhizal plant was shown. The genome sizes of three Frankia species, Frankia EANpec, ACN14a and CcI3, are different, revealing a relationship between genome size and geographical distribution. Recent genomic sequencing data of Frankia represent genomes from cluster I to IV, indicating that the genome of DgI is one of the smallest genomes in Frankia. In addition, nonsymbiotic Frankiales such as Acidothermus cellulolyticus, Blastococcus saxoobsidens, Geodermatophilus obscurus and Modestobacter marinus have a variety of genome sizes ranging from 2.4 to 5.57Mb.
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| 30. |
- Westerholm, Maria
(author)
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Dual investigation of methanogenic processes by quantitative PCR and quantitative microscopic fingerprinting
- 2014
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 360, s. 76-84
-
Journal article (peer-reviewed)abstract
- Monitoring of methanogenic communities in anaerobic digesters using molecular-based methods is very attractive but can be cost-intensive. A new and fast quantification method by microscopic image analysis was developed to accompany molecular-based methods. This digitalized method, called quantitative microscopic fingerprinting (QMF), enables quantification of active methanogenic cells (NmL(-1)) by their characteristic auto-fluorescence based on coenzyme F-420. QMF was applied to analyze the methanogenic communities in three biogas plant samples, and the results were compared with the relative proportion of gene copy numbers obtained with the quantitative PCR (qPCR). Analysis of QMF demonstrated dominance of Methanomicrobiales and Methanobacteriales in relation to the total methanogenic community in digesters operating at high ammonia concentrations, which corresponded to the results established by qPCR. Absolute microbial counts by QMF and the numbers obtained by qPCR were not always comparable. On the other hand, the restricted morphological analysis by QMF was enhanced by the capability of qPCR to identify microbes. Consequently, dual investigations of both methods are proposed to improve monitoring of anaerobic digesters. For a rough estimation of the methanogenic composition in anaerobic digesters, the QMF method seems to be a promising approach for the rapid detection of microbial changes.
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| 31. |
- Andersson, Sofia, et al.
(author)
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Biofilm formation and interactions of bacterial strains found in wastewater treatment systems
- 2008
-
In: FEMS Microbiology Letters. - OXFORD : BLACKWELL PUBLISHING. - 0378-1097 .- 1574-6968. ; 283:1, s. 83-90
-
Journal article (peer-reviewed)abstract
- Biofilm formation and adherence properties of 13 bacterial strains commonly found in wastewater treatment systems were studied in pure and mixed cultures using a crystal violet microtiter plate assay. Four different culture media were used, wastewater, acetate medium, glucose medium and diluted nutrient broth. The medium composition strongly affected biofilm formation. All strains were able to form pure culture biofilms within 24 h in at least one of the tested culture media and three strains were able to form biofilm in all four culture media, namely Acinetobacter calcoaceticus ATCC 23055, Comamonas denitrificans 123 and Pseudomonas aeruginosa MBL 0199. The adherence properties assessed were initial adherence, cell surface hydrophobicity, and production of amyloid fibers and extracellular polymeric substances. The growth of dual-strain biofilms showed that five organisms formed biofilm with all 13 strains while seven formed no or only weak biofilm when cocultured. In dual-strain cultures, strains with different properties were able to complement each other, giving synergistic effects. Strongest biofilm formation was observed when a mixture of all 13 bacteria were grown together. These results on attachment and biofilm formation can serve as a tool for the design of tailored systems for the degradation of municipal and industrial wastewater.
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| 32. |
- Arthurson, Veronica, et al.
(author)
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Persistence and spread of Salmonella enterica serovar Weltevreden in soil and on spinach plants
- 2011
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 314, s. 67-74
-
Journal article (peer-reviewed)abstract
- Several outbreaks caused by pathogenic bacteria are related to the consumption of raw produce contaminated by animal manure. The majority of these outbreaks have been linked to Salmonella spp. We examined the ability of Salmonella enterica serovar Weltevreden to persist and survive in manure and soil as well as disseminate to, and persist on, spinach roots and leaves. Significantly higher numbers of S. Weltevreden inoculated into manure and applied to soil before planting spinach were found in soil than in pot cultures, where the pathogen had been inoculated directly into soil 14 days postplanting. Moreover, the pathogen seemed to disperse from manure to spinach roots, as we observed a continuous increase in the number of contaminated replicate pot cultures throughout the evaluation period. We also found that, in some cases, S. Weltevreden present in the phyllosphere had the ability to persist for the entire evaluation period (21 days), with only slight reductions in cell numbers. The results from the present study show that S. Weltevreden is capable of persisting in soil, roots and shoots for prolonged periods, indicating the importance of strict monitoring of untreated animal manure before considering its application to agricultural land.
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| 33. |
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| 34. |
- Bontempi, EJ, et al.
(author)
-
The tyrosine aminotransferase from Trypanosoma rangeli : sequence andgenomic characterization
- 2000
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 189:2, s. 253-257
-
Journal article (peer-reviewed)abstract
- The complete sequence and genomic characterization of the tyrosine aminotransferase (TAT) gene from Trypanosoma rangeli is reported. The gene was found to be organized in a tandem multicopy gene array. A homologous mRNA species (2.5 kb) was identified in the epimastigote form of the parasite. From the deduced amino acid sequence, the gene encodes a protein of 420 amino acids with a predicted molecular mass of 46.4 kDa and a theoretical pI of 6.23. A high sequence identity was found with the Trypanosoma cruzi, human and rat enzymes. All the essential residues for TAT enzymatic activity are conserved, as well as a pyridoxal-phosphate attachment site typical of class-I aminotransferases. The recombinant enzyme was recognized by a monoclonal antibody against the T. cruzi enzyme. Additionally, the recombinant protein showed enzymatic activity when incubated with L-tyrosine and 2-oxoglutaric acid as substrates.
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| 35. |
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| 36. |
- Camsund, Daniel, et al.
(author)
-
A HupS-GFP fusion protein demonstrates a heterocyst-specific localization of the uptake hydrogenase in Nostoc punctiforme
- 2011
-
In: FEMS Microbiology Letters. - : John Wiley & Sons. - 0378-1097 .- 1574-6968. ; 316:2, s. 152-159
-
Journal article (peer-reviewed)abstract
- All diazotrophic filamentous cyanobacteria contain an uptake hydrogenase that is involved in the reoxidation of H-2 produced during N-2-fixation. In Nostoc punctiforme ATCC 29133, N-2-fixation takes place in the microaerobic heterocysts, catalysed by a nitrogenase. Although the function of the uptake hydrogenase may be closely connected to that of nitrogenase, the localization in cyanobacteria has been under debate. Moreover, the subcellular localization is not understood. To investigate the cellular and subcellular localization of the uptake hydrogenase in N. punctiforme, a reporter construct consisting of the green fluorescent protein (GFP) translationally fused to HupS, within the complete hupSL operon, was constructed and transferred into N. punctiforme on a self-replicative vector by electroporation. Expression of the complete HupS-GFP fusion protein was confirmed by Western blotting using GFP antibodies. The N. punctiforme culture expressing HupS-GFP was examined using laser scanning confocal microscopy, and fluorescence was exclusively detected in the heterocysts. Furthermore, the fluorescence in mature heterocysts was localized to several small or fewer large clusters, which indicates a specificity of the subcellular localization of the uptake hydrogenase.
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| 37. |
- Dominguez-Escobar, Julia, et al.
(author)
-
Phylogenetic and molecular clock inferences of cyanobacterial strains within Rivulariaceae from distant environments
- 2011
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 316:2, s. 90-99
-
Journal article (peer-reviewed)abstract
- Heterocyst-forming cyanobacteria are important players at both evolutionary and ecological scales, but to date it has been difficult to establish their phylogenetic affiliations. We present data from a phylogenetic and molecular clock analysis of heterocystous cyanobacteria within the family Rivulariaceae, including the genera Calothrix, Rivularia, Gloeotrichia and Tolypothrix. The strains were isolated from distant geographic regions including fresh and brackish water bodies, microbial mats from beach rock, microbialites, pebble beaches, plus PCC strains 7103 and 7504. Phylogenetic inferences (distance, likelihood and Bayesian) suggested the monophyly of genera Calothrix and Rivularia. Molecular clock estimates indicate that Calothrix and Rivularia originated similar to 1500 million years ago (MYA) ago and species date back to 400-300 MYA while Tolypothrix and Gloeotrichia are younger genera (600-400 MYA).
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| 38. |
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| 39. |
- Graslund, S., et al.
(author)
-
Single-vector three-frame expression systems for affinity-tagged proteins
- 2002
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 215:1, s. 139-147
-
Journal article (peer-reviewed)abstract
- An effort is presented to create expression vectors which would allow expression of an inserted gene fragment in three reading frames in a single vector from a single promoter but with three separate ribosome binding sites (RBS). Each expression frame would generate an in-frame fusion with an affinity tag to allow efficient recovery of the produced fusion proteins. In the first generation vector, three identical polyhistidyl tags (His(6)) were used as affinity tags for the three expression frames. In the second generation vector, three different tags, an albumin binding domain derived from streptococcal protein G, an IgG binding Staphylococcus aureus protein A-derived domain (Z) and a His(6) tag, were employed to allow frame-specific affinity recovery. To evaluate the systems, model genes have been inserted in three different frames in both vectors. The first vector was demonstrated to produce fusion proteins in all three frames, whereas for the second, with a much wider spacing between the RBSs and affinity tags, expression could only be demonstrated from the first two translational start sites. For both systems, the first translation start was found to be significantly favored over the others. Nevertheless, we believe that the presented results represent the first successful attempt to create single-vector three-frame expression systems, a concept that could become valuable in future combined cloning-expression vectors.
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| 40. |
- Gustafsson, Erik, et al.
(author)
-
Maximal transcription of aur (aureolysin) and sspA (serine protease) in Staphylococcus aureus requires staphylococcal accessory regulator R (sarR) activity
- 2008
-
In: FEMS Microbiology Letters. - : Blackwell Publishing. - 0378-1097 .- 1574-6968. ; 284:2, s. 158-164
-
Journal article (peer-reviewed)abstract
- Previous studies have shown that expression of aur (metalloprotease; aureolysin) and sspA (V8 protease; serine protease) in Staphylococcus aureus strain 8325-4 is maximal in the postexponential phase of growth, when the agr (RNAIII) system is activated. Transcription of aur and sspA is mainly regulated through repression by sarA and rot, and RNAIII stimulates protease production by inhibiting translation of rot mRNA. As SarR is a repressor of sarA, inactivation of sarR would result in downregulation of aur and sspA transcription. This was confirmed by mRNA analysis using quantitative real-time PCR. However, we found that sarR acted as a direct stimulator, i.e. its positive effect on aur and sspA transcription did not require sarA (or rot) per se. In addition, aur and sspA were dependent on sarR for maximal transcription. This stimulating role of sarR was not restricted to the rsbU-deficient laboratory strain 8325-4 but was also demonstrated in S. aureus strain SH1000 (rsbU-complemented derivative of 8325-4) and in one clinical isolate.
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| 41. |
- Hansson, M., et al.
(author)
-
General expression vectors for Staphylococcus carnosus enabled efficient production of the outer membrane protein A of Klebsiella pneumoniae
- 2002
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 210:2, s. 263-270
-
Journal article (peer-reviewed)abstract
- General expression vectors, designed for intracellular expression or secretion of recombinant proteins in the non-pathogenic Staphylococcus carnosus, were constructed. Both vector systems encode two different affinity tags, an upstream albumin binding protein and a downstream hexahistidyl peptide, and are furnished with cleavage sites for two site-specific proteases for optional affinity tag removal. To evaluate the novel vectors, the gene encoding the outer membrane protein A (OmpA) of Klebsiella pneumoniae was introduced into the vectors. Efficient production was demonstrated in both systems, although, as expected for OmpA fusions, somewhat better intracellularly, and the fusion proteins could be recovered as full-length products by affinity chromatography.
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| 42. |
- Hernandez, Marcela, et al.
(author)
-
Isolation and characterization of a novel simazine-degrading bacterium from agricultural soil of central Chile, Pseudomonas sp MHP41
- 2008
-
In: Fems Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 286:2, s. 184-190
-
Journal article (peer-reviewed)abstract
- s-Triazine herbicides are used extensively in South America in agriculture and forestry. In this study, a bacterium designated as strain MHP41, capable of degrading simazine and atrazine, was isolated from agricultural soil in the Quillota valley, central Chile. Strain MHP41 is able to grow in minimal medium, using simazine as the sole nitrogen source. In this medium, the bacterium exhibited a growth rate of μ=0.10 h−1, yielding a high biomass of 4.2 × 108 CFU mL−1. Resting cells of strain MHP41 degrade more than 80% of simazine within 60 min. The atzA, atzB, atzC, atzD, atzE and atzF genes encoding the enzymes of the simazine upper and lower pathways were detected in strain MHP41. The motile Gram-negative bacterium was identified as a Pseudomonas sp., based on the Biolog microplate system and comparative sequence analyses of the 16S rRNA gene. Amplified ribosomal DNA restriction analysis allowed the differentiation of strain MHP41 from Pseudomonas sp. ADP. The comparative 16S rRNA gene sequence analyses suggested that strain MHP41 is closely related to Pseudomonas nitroreducens and Pseudomonas multiresinovorans. This is the first s-triazine-degrading bacterium isolated in South America. Strain MHP41 is a potential biocatalyst for the remediation of s-triazine-contaminated environments.
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| 43. |
- Izumi, Hironari, et al.
(author)
-
Bacteria associated with ectomycorrhizas of slash pine (Pinus elliottii) in south-eastern Queensland, Australia
- 2008
-
In: Fems Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 282:2, s. 196-204
-
Journal article (peer-reviewed)abstract
- Bacterial communities associated with ectomycorrhizal and uncolonized roots of Pinus elliottii (slash pine) collected from a plantation in south-east Queensland, Australia, were investigated, using cultivation-dependent and -independent methods. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene PCR products obtained using a cultivation-independent approach revealed that bacterial communities associated with ectomycorrhizal root tips differed significantly from those associated with roots uncolonized by ectomycorrhizal fungi. DGGE analysis of cultivable bacterial communities revealed no significant difference between ectomycorrhizal and uncolonized roots. Neither analytical approach revealed significant differences between the bacterial communities associated with ectomycorrhizal roots colonized by a Suillus sp. or an Atheliaceae taxon. Cloned bacterial 16S rRNA genes revealed sequence types closely related with that of Burkholderia phenazinium, common in both ectomycorrhizal-colonized and -uncolonized roots, while sequence types most similar to the potentially phyopathogenic bacteria Burkholderia andropogonis and Pantoea ananatis were only detected in ectomycorrhizal roots. These results highlight the possibility of global movement of microorganisms, including putative pathogens, as a result of the introduction of exotic pine plantations.
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| 44. |
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| 45. |
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| 46. |
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| 47. |
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| 48. |
- Karlsson, Roger, 1975, et al.
(author)
-
Identification of key proteins involved in the anammox reaction
- 2009
-
In: FEMS microbiology letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 297:1, s. 87-94
-
Journal article (peer-reviewed)abstract
- Bacteria performing anaerobic ammonium oxidation (anammox) are key players in the global nitrogen cycle due to their inherent ability to convert biologically available nitrogen to N(2). Anammox is increasingly being exploited during wastewater treatment worldwide, and about 50% of the total N(2) production in marine environments is estimated to proceed by the anammox pathway. To fully understand the microbial functionality and mechanisms that control environmental feedbacks of the anammox reaction, key proteins involved in the reaction must be identified. In this study we have utilized an analytical protocol that facilitates detection of proteins associated with the anammoxosome, an intracellular membrane compartment within the anammox bacterium. The protocol enabled us to identify several key proteins of the anammox reaction including a hydrazine hydrolase producing hydrazine, a hydrazine-oxidizing enzyme converting hydrazine to N(2) and a membrane-bound ATP synthase generating ATP from the gradients of protons formed in the anammox reaction. We also performed immunogold labelling electron microscopy to determine the subcellular location of the hydrazine hydrolase. The results from our study support the hypothesis that proteins associated with the anammoxosome host the complete suite of reactions during anammox.
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| 49. |
- Kronqvist, Nina, et al.
(author)
-
Simplified characterization through site-specific protease-mediated release of affinity proteins selected by staphylococcal display
- 2008
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 278:1, s. 128-136
-
Journal article (peer-reviewed)abstract
- The production of candidate affinity proteins in a soluble form, for downstream characterization, is often a time-consuming step in combinatorial protein engineering methods. Here, a novel approach for efficient production of candidate clones is described based on direct cleavage of the affinity protein from the surface of Staphylococcus carnosus, followed by affinity purification. To find a suitable strategy, three new fusion protein constructs were created, introducing a protease site for specific cleavage and purification tags for affinity chromatography purifications into the staphylococcal display vector. The three modified strains were evaluated in terms of transformation frequency, surface expression level and protease cleavage efficiency. A protocol for efficient affinity purification of protease-released affinity proteins using the introduced fusion-tags was successfully used, and the functionality of protease-treated and purified proteins was verified in a biosensor assay. To evaluate the devised method, a previously selected HER2-specific affibody was produced applying the new principle and was used to analyze HER2 expression on human breast cancer cells.
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| 50. |
- Kuttuva, Gunaratna R., et al.
(author)
-
Peptide-mediated delivery of green fluorescent protein into yeasts and bacteria
- 2002
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 215:2, s. 267-272
-
Journal article (peer-reviewed)abstract
- Stringent microbial cell barriers limit the application of many substances in research and therapeutics. Carrier peptides that penetrate or translocate across cell membranes may help overcome this problem. To assess peptide-mediated delivery into two yeast and three bacterial species, a range of cell penetrating and signal peptide sequences were fused to green fluorescent protein (GFP), expressed in Escherichia coli, partially purified and incubated with growing cells. Fluorescence microscopy indicated several peptides that mediated delivery. In particular, VLTNENPFSDP efficiently delivered GFP into Candida albicans and Staphylococcus aureus, while YKKSNNPFSD was most efficient for Bacillus subtilis and CFFKDEL for Escherichia coli. Carrier peptides may improve delivery of certain large molecular mass molecules into microorganisms for research and therapeutic applications.
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