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Lauren B Jones, Pallab Ghosh, Jung-Hyun Lee, Chia-Ni Chou, Daniel A Kunz
A genetic linkage between a conserved gene cluster (Nit1C) and the ability of bacteria to utilize cyanide as the sole nitrogen source was demonstrated for nine different bacterial species. These included three strains whose cyanide nutritional ability has formerly been documented (Pseudomonas fluorescens Pf11764, Pseudomonas putida BCN3 and Klebsiella pneumoniae BCN33), and six not previously known to have this ability [Burkholderia (Paraburkholderia) xenovorans LB400, Paraburkholderia phymatum STM815, Paraburkholderia phytofirmans PsJN, Cupriavidus (Ralstonia) eutropha H16, Gluconoacetobacter diazotrophicus PA1 5 and Methylobacterium extorquens AM1]...
May 21, 2018: Microbiology
Tania Kalsotra, Shikha Khullar, Radhika Agnihotri, Mondem Sudhakara Reddy
Metallothioneins (MTs) are small proteins with highly conserved cysteine residues and are involved in metal homeostasis and metal detoxification. Two metallothionein genes ShMT1 and ShMT2 from the ectomycorrhizal fungus Suillus himalayensis were characterised for their potential role in heavy metal detoxification. The response of these MTs to the exogenous concentrations of copper and cadmium was studied by qPCR analysis. The exogenous copper but not the cadmium at the tested concentrations induced the expression of the MT genes...
May 15, 2018: Microbiology
Kamila K Myka, Peter McGlynn, Gail P Ferguson
How DNA metabolism is adapted to survival of organisms such as the bacterium Photobacterium profundum SS9 at high pressure is unknown. Previously, a high pressure-sensitive P. profundum SS9 transposon mutant (FL31) was identified, with an insertion in a putative rctB gene. The Vibrio cholerae RctB protein is essential for replication initiation at the origin of chromosome II, oriCII. Using a plasmid-based system in E. coli we have identified the replication origin of chromosome II from P. profundum SS9 and have shown that the putative rctB gene, disrupted in FL31, is essential for oriCII function...
May 14, 2018: Microbiology
Denitsa Eckweiler, Susanne Häussler
A large number of antisense transcripts have been detected in diverse microbial genomes and considerable effort has been devoted to elucidating the functional role of antisense transcription. In this study, we reanalysed extensive RNA sequencing data from the opportunistic pathogen Pseudomonas aeruginosa and found that the majority of genes have a propensity for antisense transcription. Although antisense transcripts were found in more than 80 % of the genes of the P. aeruginosa genome, the majority of sequencing reads were mapping sense and only a minority (<2 %) were mapping antisense to genes...
May 8, 2018: Microbiology
Nanna B Svenningsen, Esteban Martínez-García, Mette H Nicolaisen, Victor de Lorenzo, Ole Nybroe
In natural environments most bacteria live in biofilms embedded in complex matrices of extracellular polymeric substances (EPS). This lifestyle is known to increase protection against environmental stress. Pseudomonas putida mt-2 harbours genes for the production of at least four different EPS polysaccharides, including alginate and cellulose. Little is known about the functional properties of cellulose, while alginate attenuates the accumulation of reactive oxygen species (ROS) caused by matric stress. By using mutants that are deficient in either alginate or cellulose production we show that even cellulose attenuates the accumulation of matric stress-induced ROS for cells in biofilms...
May 8, 2018: Microbiology
Hiroaki Takeuchi, Mizuki Kira, Sayuri Konishi, Jumpei Uchiyama, Shigenobu Matsuzaki, Yoshihisa Matsumura
This study aimed to determine the characteristics of the Helicobacter pylori host NY43 strain and its prophage-cured derivative. H. pylori colonizing the human stomach cause many diseases. They show high genetic diversity, allowing the development of mutant strains that can form bacterial communities adapted to specific environmental conditions. Bacteriophage activities are associated with bacterial evolution, including pathogenicity development. Herein, we reported the complete genome sequence and genomic organization of two H...
May 8, 2018: Microbiology
Charlotte Wermser, Daniel Lopez
The human pathogen Staphylococcus aureus causes difficult-to-eradicate biofilm-associated infections that generally become chronic. Understanding the genetic regulation of biofilm formation in S. aureus is central to a precise definition of the conditions and genes involved in development of chronic biofilm-associated infections. Biofilm-related genes have been detected by comparing mutants using the classical submerged biofilm formation assay, in which cells adhere to the bottom of a well containing culture medium...
April 11, 2018: Microbiology
Rhishita Chourashi, Suman Das, Debarpan Dhar, Keinosuke Okamoto, Asish K Mukhopadhyay, Nabendu Sekhar Chatterjee
Vibrio cholerae regularly colonizes the chitinous exoskeleton of crustacean shells in the aquatic region. The type 6 secretion system (T6SS) in V. cholerae is an interbacterial killing device. This system is thought to provide a competitive advantage to V. cholerae in a polymicrobial community of the aquatic region under nutrient-poor conditions. V. cholerae chitin sensing is known to be initiated by the activation of a two-component sensor histidine kinase ChiS in the presence of GlcNAc2 (N,N'-diacetylchitobiose) residues generated by the action of chitinases on chitin...
April 10, 2018: Microbiology
Yiyang Yu, Fang Yan, Yinghao He, Yuxuan Qin, Yun Chen, Yunrong Chai, Jian-Hua Guo
ATP-dependent proteases play essential roles in both protein quality control and the regulation of protein activities in bacteria. ClpYQ (also known as HslVU) is one of several highly conserved ATP-dependent proteases in bacteria. The regulation and biological function of ClpYQ have been well studied in Gram-negative bacteria, but are poorly understood in Gram-positive species. In this study, we showed that in the Gram-positive bacterium Bacillus subtilis, the ΔclpYQ deletion mutant formed early and robust biofilms, while swarming motility was severely impaired...
April 9, 2018: Microbiology
Abigail J Sporer, Christopher Beierschmitt, Anastasia Bendebury, Katherine E Zink, Alexa Price-Whelan, Marisa C Buzzeo, Laura M Sanchez, Lars E P Dietrich
The activities of critical metabolic and regulatory proteins can be altered by exposure to natural or synthetic redox-cycling compounds. Many bacteria, therefore, possess mechanisms to transport or transform these small molecules. The opportunistic pathogen Pseudomonas aeruginosa PA14 synthesizes phenazines, redox-active antibiotics that are toxic to other organisms but have beneficial effects for their producer. Phenazines activate the redox-sensing transcription factor SoxR and thereby induce the transcription of a small regulon, including the operon mexGHI-opmD, which encodes an efflux pump that transports phenazines, and PA14_35160 (pumA), which encodes a putative monooxygenase...
April 9, 2018: Microbiology
Sneha Garge, Sheyda Azimi, Stephen P Diggle
Here we highlight the development of a simple and high-throughput mung bean model to study virulence in the opportunistic pathogen Pseudomonas aeruginosa. The model is easy to set up, and infection and virulence can be monitored for up to 10 days. In a first test of the model, we found that mung bean seedlings infected with PAO1 showed poor development of roots and high mortality rates compared to uninfected controls. We also found that a quorum-sensing (QS) mutant was significantly less virulent when compared with the PAO1 wild-type...
April 9, 2018: Microbiology
Ryoichi Saito, Prabhat K Talukdar, Saud S Alanazi, Mahfuzur R Sarker
RelA is a global regulator for stationary phase development in the model bacterium Bacillus subtilis. The relA gene forms a bicistronic operon with the downstream dtd gene. In this study, we evaluated the significance of RelA and DTD proteins in spore formation and toxin production by an important gastrointestinal pathogen Clostridium perfringens. Our β-glucuronidase assay showed that in C. perfringens strain SM101, relA forms a bicistronic operon with its downstream dtd gene, and the relA promoter is expressed during both vegetative and sporulation conditions...
April 6, 2018: Microbiology
Pauline Schaap, Christina Schilde
Not long ago, protists were considered one of four eukaryote kingdoms, but recent gene-based phylogenies show that they contribute to all nine eukaryote subdomains. The former kingdoms of animals, plants and fungi are now relegated to lower ranks within subdomains. Most unicellular protists respond to adverse conditions by differentiating into dormant walled cysts. As cysts, they survive long periods of starvation, drought and other environmental threats, only to re-emerge when conditions improve. For protists pathogens, the resilience of their cysts can prevent successful treatment or eradication of the disease...
April 5, 2018: Microbiology
Franziska Jäger, Holger Kneuper, Tracy Palmer
The type VII protein secretion system (T7SS) is found in actinobacteria and firmicutes, and plays important roles in virulence and interbacterial competition. A membrane-bound ATPase protein, EssC in Staphylococcus aureus, lies at the heart of the secretion machinery. The EssC protein from S. aureus strains can be grouped into four variants (EssC1-EssC4) that display sequence variability in the C-terminal region. Here we show that the EssC2, EssC3 and EssC4 variants can be produced in a strain deleted for essC1, and that they are able to mediate secretion of EsxA, an essential component of the secretion apparatus...
April 5, 2018: Microbiology
Tomoharu Inoue, Clive S Barker, Hideyuki Matsunami, Shin-Ichi Aizawa, Fadel A Samatey
Campylobacter jejuni cells have bipolar flagella. Both flagella have similar lengths of about one helical turn, or 3.53±0.52 µm. The flagellar filament is composed of two homologous flagellins: FlaA and FlaB. Mutant strains that express either FlaA or FlaB alone produce filaments that are shorter than those of the wild-type. It is reported that the flaG gene could affect filament length in some species of bacteria, but its function remains unknown. We introduced a flaG-deletion mutation into the C. jejuni wild-type strain and flaA- or flaB-deletion mutant strains, and observed their flagella by microscopy...
March 29, 2018: Microbiology
Ya Xu, Bang-Ce Ye
The limited catalytic efficiency of cellulose-degrading enzymes restricts cellulose digestion. We investigated the transcriptional regulation of genes encoding key cellulose degrading enzymes, namely β-glucosidases, in the industrial actinobacterium Saccharopolyspora erythraea. We observed that the expression of most β-glucosidase-encoding genes was controlled by the availability of nitrogen and phosphate via their respective global regulators, namely GlnR and PhoP. Electrophoretic mobility shift assay demonstrated that GlnR and PhoP bound directly to the promoters of β-glucosidase-encoding genes...
March 27, 2018: Microbiology
Naoki Sudo, Akiko Soma, Sunao Iyoda, Taku Oshima, Yui Ohto, Kenta Saito, Yasuhiko Sekine
Enterohaemorrhagic Escherichia coli (EHEC) is a life-threatening human pathogen worldwide. The locus of enterocyte effacement (LEE) in EHEC encodes a type three secretion system and effector proteins, all of which are essential for bacterial adherence to host cells. When LEE expression is activated, flagellar gene expression is down-regulated because bacterial flagella induce the immune responses of host cells at the infection stage. Therefore, this inverse regulation is also important for EHEC infection. We report here that a small regulatory RNA (sRNA), Esr41, mediates LEE repression and flagellar gene activation...
March 26, 2018: Microbiology
Huan Liu, Gang Wang, Wei Li, Xingzhong Liu, Erwei Li, Wen-Bing Yin
Trichoderma hypoxylon is a fungicolous species which produces rich secondary metabolites. However, no genetic transformation method is available for further studies. Here, we developed a marker-less transformation system based on the complementation of an uridine/uracil biosynthetic gene by protoplast transformation. An uridine/uracil auxotrophic mutant of Δthpyr4 was obtained by using a positive screening protocol with 5'-fluoroorotic acid as a selective reagent. To improve the homologous integration rates, the orthologues of ku70 and lig4 which play critical roles in non-homologous end-joining recombination were disrupted...
March 19, 2018: Microbiology
Yonglin Wang, Xiaoping Hu, Yulin Fang, Amy Anchieta, Polly H Goldman, Gustavo Hernandez, Steven J Klosterman
No abstract text is available yet for this article.
May 2018: Microbiology
Robert Howlett, Nicholas Read, Anpu Varghese, Charles Kershaw, Y Hancock, Margaret C M Smith
No abstract text is available yet for this article.
April 2018: Microbiology
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