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Microbiology

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https://www.readbyqxmd.com/read/29231156/efficient-bio-production-of-citramalate-using-an-engineered-escherichia-coli-strain
#1
Joseph P Webb, S Alison Arnold, Scott Baxter, Stephen J Hall, Graham Eastham, Gill Stephens
Citramalic acid is a central intermediate in a combined biocatalytic and chemocatalytic route to produce bio-based methylmethacrylate, the monomer used to manufacture Perspex and other high performance materials. We developed an engineered E. coli strain and a fed-batch bioprocess to produce citramalate at concentrations in excess of 80 g l-1 in only 65 h. This exceptional efficiency was achieved by designing the production strain and the fermentation system to operate synergistically. Thus, a single gene encoding a mesophilic variant of citramalate synthase from Methanococcus jannaschii, CimA3...
December 12, 2017: Microbiology
https://www.readbyqxmd.com/read/29219809/the-cell-wall-of-the-filamentous-anoxygenic-phototrophic-bacterium-oscillochloris-trichoides
#2
Olga I Keppen, Ruslan N Ivanovsky, Galina M Streshinskaya, Natalia V Lebedeva, Alexander S Shashkov, Andrey S Dmitrenok, Denis S Grouzdev
The filamentous anoxygenic phototrophic bacterium Oscillochloris trichoides DG-6 has been studied, and it has been shown that there are no lipopolysaccharides on the cell surface. Fatty acids hydroxylated at the C3 position, amino sugars and phosphate-containing compounds characteristic of lipid A have also not been found. The genes encoding for proteins responsible for the synthesis of lipopolysaccharides and the genes for the transport system, usually localized in the outer membrane of Gram-negative bacteria, have not been detected in the genome...
December 8, 2017: Microbiology
https://www.readbyqxmd.com/read/29219805/car-gene-cluster-and-transcript-levels-of-carotenogenic-genes-in-rhodotorula-mucilaginosa
#3
Sara Landolfo, Giuseppe Ianiri, Salvatore Camiolo, Andrea Porceddu, Giuliana Mulas, Rossella Chessa, Giacomo Zara, Ilaria Mannazzu
A molecular approach was applied to the study of the carotenoid biosynthetic pathway of Rhodotorula mucilaginosa. At first, functional annotation of the genome of R. mucilaginosa C2.5t1 was carried out and gene ontology categories were assigned to 4033 predicted proteins. Then, a set of genes involved in different steps of carotenogenesis was identified and those coding for phytoene desaturase, phytoene synthase/lycopene cyclase and carotenoid dioxygenase (CAR genes) proved to be clustered within a region of ~10 kb...
December 8, 2017: Microbiology
https://www.readbyqxmd.com/read/29214973/expression-of-the-small-regulatory-rna-gene-mmgr-is-regulated-negatively-by-ania-and-positively-by-ntrc-in-sinorhizobium-meliloti-2011
#4
Germán Ceizel Borella, Antonio Lagares, Claudio Valverde
In the N2-fixing symbiont of alfalfa root nodules, Sinorhizobium meliloti 2011, the mmgR gene encodes a 77 nt small untranslated RNA (sRNA) that negatively regulates the accumulation of polyhydroxybutyrate (PHB) when the bacterium is grown under conditions of surplus carbon (C) in relation to nitrogen (N). We previously showed that the expression of mmgR is primarily controlled at the transcriptional level and that it depends on the cellular N status, although the regulatory mechanism and the factors involved were unknown...
December 7, 2017: Microbiology
https://www.readbyqxmd.com/read/29205130/impact-of-stress-on-the-gut-microbiome-of-free-ranging-western-lowland-gorillas
#5
Klára Vlčková, Kathryn Shutt-Phillips, Michael Heistermann, Barbora Pafčo, Klára J Petrželková, Angelique Todd, David Modrý, Karen E Nelson, Brenda A Wilson, Rebecca M Stumpf, Bryan A White, Steven R Leigh, Andres Gomez
Exposure to stressors can negatively impact the mammalian gastrointestinal microbiome (GIM). Here, we used 454 pyrosequencing of 16S rRNA bacterial gene amplicons to evaluate the impact of physiological stress, as evidenced by faecal glucocorticoid metabolites (FGCM; ng/g), on the GIM composition of free-ranging western lowland gorillas (Gorilla gorilla gorilla). Although we found no relationship between GIM alpha diversity (H) and FGCM levels, we observed a significant relationship between the relative abundances of particular bacterial taxa and FGCM levels...
December 5, 2017: Microbiology
https://www.readbyqxmd.com/read/29205129/dissimilar-pigment-regulation-in-serpula-lacrymans-and-paxillus-involutus-during-inter-kingdom-interactions
#6
James P Tauber, Ramses Gallegos-Monterrosa, Ákos T Kovács, Ekaterina Shelest, Dirk Hoffmeister
Production of basidiomycete atromentin-derived pigments like variegatic acid (pulvinic acid-type) and involutin (diarylcyclopentenone) from the brown-rotter Serpula lacrymans and the ectomycorrhiza-forming Paxillus involutus, respectively, is induced by complex nutrition, and in the case of S. lacrymans, bacteria. Pigmentation in S. lacrymans was stimulated by 13 different bacteria and cell-wall-damaging enzymes (lytic enzymes and proteases), but not by lysozyme or mechanical damage. The use of protease inhibitors with Bacillus subtilis or heat-killed bacteria during co-culturing with S...
December 5, 2017: Microbiology
https://www.readbyqxmd.com/read/29185954/divalent-cations-increase-the-conjugation-efficiency-of-the-incompatibility-p-7-group-plasmid-pcar1-among-different-pseudomonas-hosts
#7
Ayako Sakuda, Chiho Suzuki-Minakuchi, Kazuhiro Matsui, Yurika Takahashi, Kazunori Okada, Hisakazu Yamane, Masaki Shintani, Hideaki Nojiri
The incompatibility (Inc) P-7 group plasmid pCAR1 can be efficiently transferred among bacteria in artificial microcosms in the presence of divalent cations Ca2+ and Mg2+. One-on-one mating assays between Pseudomonas strains with different plasmids showed that the promotion of conjugation efficiency by divalent cations was exhibited in other plasmids, including pB10 and NAH7; however, this effect was larger in IncP-7 plasmids. The impact on pCAR1 conjugation differed according to donor-recipient pairs, and conjugation efficiency promotion was clearly detected between the donors P...
November 29, 2017: Microbiology
https://www.readbyqxmd.com/read/29182512/global-mapping-of-mtra-binding-sites-links-mtra-to-regulation-of-its-targets-in-mycobacterium-tuberculosis
#8
Ayan Chatterjee, Arun Kumar Sharma, Amar Chandra Mahatha, Srijon Kaushik Banerjee, Manish Kumar, Sudipto Saha, Joyoti Basu, Manikuntala Kundu
Mycobacterium tuberculosis employs two-component systems (TCSs) for survival within its host. The TCS MtrAB is conserved among mycobacteria. The response regulator MtrA is essential in M. tuberculosis. The genome-wide chromatin immunoprecipitation (ChIP) sequencing performed in this study suggested that MtrA binds upstream of at least 45 genes of M. tuberculosis, including those involved in cell wall remodelling, stress responses, persistence and regulation of transcription. It binds to the promoter regions and regulates the peptidoglycan hydrolases rpfA and rpfC, which are required for resuscitation from dormancy...
November 28, 2017: Microbiology
https://www.readbyqxmd.com/read/29182511/molecular-cloning-and-overexpression-of-dga1-an-acyl-coa-dependent-diacylglycerol-acyltransferase-in-the-oleaginous-yeast-rhodosporidiobolus-fluvialis-dmku-rk253
#9
Pirapan Polburee, Takao Ohashi, Yung-Yu Tsai, Thitinun Sumyai, Noppon Lertwattanasakul, Savitree Limtong, Kazuhito Fujiyama
Triacylglycerol (TAG) is a major component of lipid storage in yeast. The acyl CoA: diacylgycerol acyltransferase (DGAT) that catalyzes the final and rate-limiting step in the production of TAG is rather interesting. Consequently, cloning and analysis of the gene-encoding TAG synthase, diacylglycerol acyltransferase gene (DGA1), of the oleaginous yeast Rhodosporidiobolus fluvialis DMKU-RK253 were undertaken. Analysis of the deduced amino acid sequence of DGA1 from R. fluvialis DMKU-RK253 (RfDGA1) showed similarity with the acyl-CoA:diacylglycerol acyltransferase 2 (DGAT2) from other organisms...
November 28, 2017: Microbiology
https://www.readbyqxmd.com/read/29171825/guardians-of-the-mycobacterial-genome-a-review-on-dna-repair-systems-in-mycobacterium-tuberculosis
#10
Amandeep Singh
The genomic integrity of Mycobacterium tuberculosis is continuously threatened by the harsh survival conditions inside host macrophages, due to immune and antibiotic stresses. Faithful genome maintenance and repair must be accomplished under stress for the bacillus to survive in the host, necessitating a robust DNA repair system. The importance of DNA repair systems in pathogenesis is well established. Previous examination of the M. tuberculosis genome revealed homologues of almost all the major DNA repair systems, i...
November 24, 2017: Microbiology
https://www.readbyqxmd.com/read/29171824/haem-iron-plays-a-key-role-in-the-regulation-of-the-ess-type-vii-secretion-system-of-staphylococcus-aureus-rn6390
#11
M Guillermina Casabona, Holger Kneuper, Daniela Alferes de Lima, Catriona P Harkins, Martin Zoltner, Erik Hjerde, Matthew T G Holden, Tracy Palmer
The Staphylococcus aureus type VII protein secretion system (T7SS) plays important roles in virulence and intra-species competition. Here we show that the T7SS in strain RN6390 is activated by supplementing the growth medium with haemoglobin, and its cofactor haemin (haem B). Transcript analysis and secretion assays suggest that activation by haemin occurs at a transcriptional and a post-translational level. Loss of T7 secretion activity by deletion of essC results in upregulation of genes required for iron acquisition...
November 24, 2017: Microbiology
https://www.readbyqxmd.com/read/29165235/synthesis-of-n-acetyl-d-quinovosamine-in-rhizobium-etli-ce3-is-completed-after-its-4-keto-precursor-is-linked-to-a-carrier-lipid
#12
Tiezheng Li, K Dale Noel
Bacterial O-antigens are synthesized on lipid carriers before being transferred to lipopolysaccharide core structures. Rhizobium etli CE3 lipopolysaccharide is a model for understanding O-antigen biological function. CE3 O-antigen structure and genetics are known. However, proposed enzymology for CE3 O-antigen synthesis has been examined very little in vitro, and even the sugar added to begin the synthesis is uncertain. A model based on mutagenesis studies predicts that 2-acetamido-2,6-dideoxy-d-glucose (QuiNAc) is the first O-antigen sugar and that genes wreV, wreQ and wreU direct QuiNAc synthesis and O-antigen initiation...
November 22, 2017: Microbiology
https://www.readbyqxmd.com/read/29165232/functional-analysis-of-the-esab-component-of-the-staphylococcus-aureus-type-vii-secretion-system
#13
M Guillermina Casabona, Grant Buchanan, Martin Zoltner, Catriona P Harkins, Matthew T G Holden, Tracy Palmer
Type VII secretion systems (T7SS) are found in many bacteria and secrete proteins involved in virulence and bacterial competition. In Staphylococcus aureus the small ubiquitin-like EsaB protein has been previously implicated as having a regulatory role in the production of the EsxC substrate. Here we show that in the S. aureus RN6390 strain, EsaB does not genetically regulate production of any T7 substrates or components, but is indispensable for secretion activity. Consistent with EsaB being an essential component of the T7SS, loss of either EsaB or EssC are associated with upregulation of a common set of iron acquisition genes...
November 22, 2017: Microbiology
https://www.readbyqxmd.com/read/29165230/para-like-protein-influences-the-distribution-of-multi-copy-chromosomes-in-cyanobacterium-synechococcus-elongatus-pcc-7942
#14
Satoru Watanabe, Aska Noda, Ryudo Ohbayashi, Kana Uchioke, Ami Kurihara, Shizuka Nakatake, Sayumi Morioka, Yu Kanesaki, Taku Chibazakura, Hirofumi Yoshikawa
While many bacteria, such as Escherichia coli and Bacillus subtilis, harbour a single-copy chromosome, freshwater cyanobacteria have multiple copies of each chromosome per cell. Although it has been reported that multi-copy chromosomes are evenly distributed along the major axis of the cell in cyanobacterium Synechococcus elongatus PCC 7942, the distribution mechanism of these chromosomes remains unclear. In S. elongatus, the carboxysome, a metabolic microcompartment for carbon fixation that is distributed in a similar manner to the multi-copy chromosomes, is regulated by ParA-like protein (hereafter ParA)...
November 21, 2017: Microbiology
https://www.readbyqxmd.com/read/29148366/involvement-of-the-ytfk-gene-from-the-phob-regulon-in-stationary-phase-h2o2-stress-tolerance-in-escherichia-coli
#15
Yumi Iwadate, Jun-Ichi Kato
The Escherichia coli PhoB-PhoR two-component system responds to phosphate starvation and induces the expression of many genes. Previous studies suggested that phosphate starvation induces oxidative stress, but the involvement of the PhoB regulon in oxidative stress tolerance has not been clarified. Here, we showed that ytfK, one of the PhoB regulon genes, is involved in cell tolerance to a redox-cycling drug, menadione, and H2O2 in stationary-phase cells. A ytfK deletion mutant was sensitive to H2O2 when the cells were grown anaerobically or micro-aerobically in the presence of nitrate...
November 17, 2017: Microbiology
https://www.readbyqxmd.com/read/29139345/herbicide-ingredients-change-salmonella-enterica-sv-typhimurium-and-escherichia-coli-antibiotic-responses
#16
Brigitta Kurenbach, Paddy S Gibson, Amy M Hill, Adam S Bitzer, Mark W Silby, William Godsoe, Jack A Heinemann
Herbicides are frequently released into both rural and urban environments. Commercial herbicide formulations induce adaptive changes in the way bacteria respond to antibiotics. Salmonella enterica sv. Typhimurium and Escherichia coli were exposed to common co-formulants of formulations, and S. enterica sv. Typhimurium was exposed to active ingredients dicamba, 2,4-D and glyphosate to determine what ingredients of the commercial formulations caused this effect. Co-formulants Tween80 and carboxymethyl cellulose induced changes in response, but the pattern of the responses differed from the active ingredients, and effect sizes were smaller...
November 17, 2017: Microbiology
https://www.readbyqxmd.com/read/29139344/aeropyrum-pernix-membrane-topology-of-protein-vkor-promotes-protein-disulfide-bond-formation-in-two-subcellular-compartments
#17
Stijntje Hibender, Cristina Landeta, Mehmet Berkmen, Jon Beckwith, Dana Boyd
Disulfide bonds confer stability and activity to proteins. Bioinformatic approaches allow predictions of which organisms make protein disulfide bonds and in which subcellular compartments disulfide bond formation takes place. Such an analysis, along with biochemical and protein structural data, suggests that many of the extremophile Crenarachaea make protein disulfide bonds in both the cytoplasm and the cell envelope. We have sought to determine the oxidative folding pathways in the sequenced genomes of the Crenarchaea, by seeking homologues of the enzymes known to be involved in disulfide bond formation in bacteria...
November 15, 2017: Microbiology
https://www.readbyqxmd.com/read/29134930/involvement-of-many-chemotaxis-sensors-in-negative-chemotaxis-to-ethanol-in-ralstonia-pseudosolanacearum-ps29
#18
Shota Oku, Akiko Hida, Tunchai Mattana, Takahisa Tajima, Yutaka Nakashimada, Junichi Kato
Ralstonia pseudosolanacearum Ps29 showed repellent responses to alcohols including methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1,3-propanediol and prenol. R. pseudosolanacearum Ps29 possesses 22 putative chemoreceptors known as methyl-accepting chemotaxis proteins (MCPs). To identify a MCP involved in negative chemotaxis to ethanol, we measured ethanol chemotaxis of a complete collection of single mcp gene deletion mutants of R. pseudosolanacearum Ps29. However, all the mutants showed repellent responses to ethanol comparable to that of the wild-type strain...
November 14, 2017: Microbiology
https://www.readbyqxmd.com/read/29125461/chemotaxis-to-self-generated-ai-2-promotes-biofilm-formation-in-escherichia-coli
#19
Sneha Jani, Andrew L Seely, George L Peabody V, Arul Jayaraman, Michael D Manson
Responses to the interspecies quorum-sensing signal autoinducer-2 (AI-2) regulate the patterns of gene expression that promote biofilm development. Escherichia coli also senses AI-2 as a chemoattractant, a response that requires the periplasmic AI-2-binding protein LsrB and the chemoreceptor Tsr. Here, we confirm, as previously observed, that under static conditions highly motile E. coli cells self-aggregate and form surface-adherent structures more readily than cells lacking LsrB and Tsr, or than ΔluxS cells unable to produce AI-2...
November 9, 2017: Microbiology
https://www.readbyqxmd.com/read/29116038/borrelia-burgdorferi-glycosaminoglycan-binding-proteins-a-potential-target-for-new-therapeutics-against-lyme-disease
#20
Yi-Pin Lin, Lingyun Li, Fuming Zhang, Robert J Linhardt
The spirochete bacterium Borrelia burgdorferisensu lato is the causative agent of Lyme disease, the most common vector-borne disease in Europe and the United States. The spirochetes can be transmitted to humans via ticks, and then spread to different tissues, leading to arthritis, carditis and neuroborreliosis. Although antibiotics have commonly been used to treat infected individuals, some treated patients do not respond to antibiotics and experience persistent, long-term arthritis. Thus, there is a need to investigate alternative therapeutics against Lyme disease...
November 8, 2017: Microbiology
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