- Comparative genotyping and phenotyping of Aspergillus fumigatus isolates from humans, dogs and the environment. [Journal Article]
- BMBMC Microbiol 2018 Sep 17; 18(1):118
- CONCLUSIONS: 1. A. fumigatus from dogs with SNA are phenotypically very diverse in contrast to their environmental and human counterparts. 2. Phenotypic variability can be induced during the chronic infection process in the sinus of the dogs. The basis of this heterogeneity might be due to genomic differences and/or epigenetic variations. 3. Differences in dogs is a could be a result of within-host adaption and might be triggered by environmental factors in the sinus, however this hypothesis still needs to be tested.
- Nitric oxide controls c-di-GMP turnover in Dinoroseobacter shibae. [Journal Article]
- MMicrobiology 2018 Sep 17
- The ubiquitous bacterial second messenger bis-(3'-5')-cyclic dimeric GMP (c-di-GMP) is involved in the regulation of numerous processes including biofilm formation, motility, virulence, cell cycle an...
The ubiquitous bacterial second messenger bis-(3'-5')-cyclic dimeric GMP (c-di-GMP) is involved in the regulation of numerous processes including biofilm formation, motility, virulence, cell cycle and differentiation. In this study, we searched the genome of the ecologically important marine alphaproteobacterium Dinoroseobacter shibae DFL12T for genes encoding putative c-di-GMP-modulating enzymes. Overall, D. shibae was found to possess two diguanylate cyclases (Dshi_2814 and Dshi_2820) as well as two c-di-GMP-specific phosphodiesterases (Dhi_0329 and Dshi_3065). Recombinant expression and purification followed by enzymatic analysis revealed that all four proteins exhibit their proposed activity. Furthermore, adjacent to Dshi_2814 we identified a gene encoding a heme nitric oxide/oxygen binding (H-NOX) protein. These proteins are often found in association with c-di-GMP signal transduction pathways and modulate their function through binding of diatomic gases such as nitric oxide. Here, we demonstrate that H-NOX constitutes a functional unit together with the diguanylate cyclase Dshi_2814. NO-bound H-NOX strongly inhibits DGC activity. Based on these results, and with respect to previously published data including micro-array analysis, we propose an interlinkage of c-di-GMP signalling with cell-cell communication and differentiation in D. shibae.
- The monofunctional cobalamin biosynthesis enzyme precorrin-3B synthase (CobZRR) is essential for anaerobic photosynthesis in Rhodospirillum rubrum but not for aerobic dark metabolism. [Journal Article]
- MMicrobiology 2018 Sep 17
- The in vivo physiological role of the gene cobZ, which encodes precorrin-3B synthase, which catalyzes the initial porphyrin ring contraction step of cobalamin biosynthesis via the cob pathway, has be...
The in vivo physiological role of the gene cobZ, which encodes precorrin-3B synthase, which catalyzes the initial porphyrin ring contraction step of cobalamin biosynthesis via the cob pathway, has been demonstrated here for the first time. Cobalamin is known to be essential for an early step of bacteriochlorophyll biosynthesis in anoxygenic purple bacteria. The cobZ (cobZRR) gene of the purple bacterium Rhodospirillum rubrum was localized to a 23.5 kb insert of chromosomal DNA contained on the cosmid pSC4. pSC4 complemented several mutants of bacteriochlorophyll and carotenoid biosynthesis, due to the presence of the bchCX and crtCDEF genes at one end of the cosmid insert, flanking cobZRR. A second gene, citB/tcuB, immediately downstream of cobZRR, shows homologies to both a tricarballylate oxidoreductase (tcuB) and a gene (citB) involved in signal transduction during citrate uptake. CobZRR shows extensive homology to the N-terminal domain of the bifunctional CobZ from Rhodobacter capsulatus, and the R. rubrum citB/tcuB gene is homologous to the CobZ C-terminal domain. A mutant, SERGK25, containing a terminatorless kanamycin interposon inserted into cobZRR, could not grow by anaerobic photosynthesis, but grew normally under dark, aerobic and microaerophilic conditions with succinate and fructose as carbon sources. The anaerobic in vivo activity of CobZ indicates that it does not require oxygen as a substrate. The mutant excreted large amounts of protoporphyrin IX-monomethylester, a brown precursor of bacteriochlorophyll biosynthesis. The mutant was complemented either by the cobZRR gene in trans, or when exogenous cobalamin was added to the medium. A deletion mutant of tcuB/citB did not exhibit the cob phenotype. Thus, a role for tcuB/citB in cobalamin biosynthesis could not be confirmed.
- Enlargement of Deinococcus grandis spheroplasts requires Mg2+ or Ca2. [Journal Article]
- MMicrobiology 2018 Sep 17
- While the cell wall strictly controls cell size and morphology in bacteria, spheroplasts lack cell walls and can become enlarged in growth medium under optimal conditions. Optimal conditions depend o...
While the cell wall strictly controls cell size and morphology in bacteria, spheroplasts lack cell walls and can become enlarged in growth medium under optimal conditions. Optimal conditions depend on the bacterial species. We frequently observed extreme enlargement of spheroplasts of the radiation-resistant bacterium Deinococcus grandis in Difco Marine Broth 2216, but not in TGY broth (a commonly used growth medium for Deinococcus). Thorough investigation of media components showed that the presence of Mg2+ or Ca2+ promoted extreme spheroplast enlargement, synthesizing the outer membrane. Our findings strongly suggest that Mg2+ or Ca2+ enlarges spheroplasts, which could change the lipid composition of the spheroplast membrane.
- Filming flagella and pili in action. [Journal Article]
- NRNat Rev Microbiol 2018; 16(10):584
- Communities at the centre. [Editorial]
- NRNat Rev Microbiol 2018; 16(10):579
- Pseudomonas aeruginosa responds to exogenous polyunsaturated fatty acids (PUFAs) by modifying phospholipid composition, membrane permeability, and phenotypes associated with virulence. [Journal Article]
- BMBMC Microbiol 2018 Sep 14; 18(1):117
- CONCLUSIONS: Our results emphasize the relevance and complexity of exogenous fatty acids in the membrane physiology and pathobiology of a medically important pathogen. P. aeruginosa exhibits versatility with regard to utilization of and response to exogenous fatty acids, perhaps revealing potential strategies for prevention and control of infection.
- HIV-1's fingerprint. [Journal Article]
- NRNat Rev Microbiol 2018 Sep 13
- A metagenome-wide association study of gut microbiota in asthma in UK adults. [Journal Article]
- BMBMC Microbiol 2018 Sep 12; 18(1):114
- CONCLUSIONS: In all, the adult human gut microbiome of asthma patients is clearly different from healthy controls. The functional and taxa results showed that the change of asthma patients might related to SCFAs.
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- The alternative sigma factor RpoQ regulates colony morphology, biofilm formation and motility in the fish pathogen Aliivibrio salmonicida. [Journal Article]
- BMBMC Microbiol 2018 Sep 12; 18(1):116
- CONCLUSIONS: The present work demonstrates that the RpoQ sigma factor is a novel regulatory component involved in modulating motility, colony morphology and biofilm formation in the fish pathogen A. salmonicida. The findings also confirm that RpoQ functions downstream of the QS master regulator LitR. However further studies are needed to elucidate how LitR and RpoQ work together in controlling phenotypes related to QS in A. salmonicida.