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Patricia Bedrunka, Fabien Olbrisch, Martina Rüger, Susanne Zehner, Nicole Frankenberg-Dinkel
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)...
September 17, 2018: Microbiology
Robin Ghosh, Erik Roth, Khaled Abou-Aisha, Rudolf Saegesser, Caroline Autenrieth
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...
September 17, 2018: Microbiology
Koki Nishino, Yusuke Morita, Sawako Takahashi, Mai Okumura, Shusaku Shiratani, Kosuke Umemura, Issay Narumi, Chie Kondo, Ryosuke Ochiai, Taku Oshima, Hiromi Nishida
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...
September 17, 2018: Microbiology
Abraham Majak Gut, Todor Vasiljevic, Thomas Yeager, Osaana N Donkor
Global Salmonella infection, especially in developing countries, is a health and economic burden. The use of antibiotic drugs in treating the infection is proving less effective due to the alarming rise of antibiotic-resistant strains of Salmonella, the effects of antibiotics on normal gut microflora and antibiotic-associated diarrhoea, all of which bring a growing need for alternative treatments, including the use of probiotic micro-organisms. However, there are issues with probiotics, including their potential to be opportunistic pathogens and antibiotic-resistant carriers, and their antibiotic susceptibility if used as complementary therapy...
August 23, 2018: Microbiology
Rebecca-Ayme Hughes, Xiaohe Jin, Yunlong Zhang, Ran Zhang, Sabrina Tran, Philip G Williams, Jonathan S Lindsey, Eric S Miller
Tolyporphins are structurally diverse tetrapyrrole macrocycles produced by the cyanobacterial culture HT-58-2. Although tolyporphins were discovered over 25 years ago, little was known about the microbiology of the culture. The studies reported herein expand the description of the community of predominantly alphaproteobacteria associated with the filamentous HT-58-2 cyanobacterium and isolate a dominant bacterium, Porphyrobacter sp. HT-58-2, for which the complete genome is established and growth properties are examined...
August 17, 2018: Microbiology
Friedrich Kirsch, Quan Luo, Xuefeng Lu, Martin Hagemann
Sucrose is naturally synthesized by many cyanobacteria under high salt conditions, which can be applied to produce this widely used feedstock. To improve sucrose production with the moderate halo-tolerant cyanobacterium Synechocystis sp. PCC 6803, we identified and biochemically characterized the sucrose-degrading invertase. Inactivating the invertase encoding gene sll0626 (inv) significantly increased cellular sucrose levels; interestingly sucrose over-accumulation was also observed under NaCl-free conditions...
August 16, 2018: Microbiology
Jiaqi Li, Connor J Gulbronson, Marek Bogacz, David R Hendrixson, Stuart A Thompson
Campylobacter jejuni is an important human pathogen that causes 96 million cases of acute diarrheal disease worldwide each year. We have shown that C. jejuni CsrA is involved in the post-transcriptional regulation of more than 100 proteins, and altered expression of these proteins is presumably involved in the altered virulence-related phenotypes of a csrA mutant. Mutation of fliW results in C. jejuni cells that have greatly truncated flagella, are less motile, less able to form biofilms, and exhibit a reduced ability to colonize chicks...
August 16, 2018: Microbiology
Alexander S Shashkov, Johanna J Kenyon, Nikolay P Arbatsky, Mikhail M Shneider, Anastasiya V Popova, Yuriy A Knirel, Ruth M Hall
The KL53 capsular polysaccharide (CPS) gene cluster of Acinetobacter baumannii D23 was sequenced, and includes a single gtr gene encoding the glycosyltransferase Gtr2, and the itrA1 gene for ItrA1 that is known to initiate CPS biosynthesis with d-QuiNAc4NAc. The K53 CPS was isolated and studied by one- and two-dimensional 1 H and 13 C nuclear magnetic resonance (NMR) spectroscopy before and after O-deacetylation. The disaccharide K unit of the CPS was established as →3)-α-d-GalpNAcA4Ac-(1→3)-β-d-QuipNAc4NAc-(1→, where GalNAcA and QuiNAc4NAc indicate 2-acetamido-2-deoxygalacturonic acid and 2,4-diacetamido-2,4,6-trideoxyglucose, respectively...
August 13, 2018: Microbiology
Cristina Colomer-Winter, Anthony O Gaca, Olivia N Chuang-Smith, José A Lemos, Kristi L Frank
The alarmone (p)ppGpp mediates the stringent response and has a recognized role in bacterial virulence. We previously reported a stringent response-like state in Enterococcus faecalis isolated from a rabbit foreign body abscess model and showed that E. faecalis mutants with varying levels of cellular (p)ppGpp [Δrel, ΔrelQ and the (p)ppGpp0 ΔrelΔrelQ] had differential abilities to persist within abscesses. In this study, we investigated whether (p)ppGpp contributes to the pathogenesis of E. faecalis infective endocarditis (IE), a biofilm infection of the heart valves...
August 9, 2018: Microbiology
Jason D Maarsingh, Shelley E Haydel
The PrrAB two-component system is conserved across all sequenced mycobacterial species and is essential for viability in Mycobacterium tuberculosis, thus making it a promising drug target. The prrAB operon was successfully deleted in nonpathogenic Mycobacterium smegmatis, and the ∆prrAB mutant strain exhibited clumping in ammonium-limited medium and significantly reduced growth during ammonium and hypoxic stress. To assess the influence of M. tuberculosis PrrA overexpression, we constructed a recombinant M...
August 7, 2018: Microbiology
Agustina Amar, Magdalena Pezzoni, Ramón A Pizarro, Cristina S Costa
Salmonella enterica serovar Typhimurium (S. typhimurium) can cause food- and water-borne illness with diverse clinical manifestations. One key factor for S. typhimurium pathogenesis is the alternative sigma factor σE , which is encoded by the rpoE gene and controls the transcription of genes required for outer-membrane integrity in response to alterations in the bacterial envelope. The canonical pathway for σE activation involves proteolysis of the antisigma factor RseA, which is triggered by unfolded outer-membrane porins (OMPs) and lipopolysaccharides (LPS) that have accumulated in the periplasm...
August 6, 2018: Microbiology
James A Budnick, Evymarie Prado-Sanchez, Clayton C Caswell
Metals are essential micronutrients for virtually all forms of life, but metal acquisition is a double-edged sword, because high concentrations of divalent cations can be toxic to the cell. Therefore, the genes involved in metal acquisition, storage and efflux are tightly regulated. The present study characterizes a nickel-responsive transcriptional regulator in the intracellular mammalian pathogen, Brucella abortus. Deletion of bab2_0432 (nikR) in B. abortus led to alterations in the nickel-responsive expression of the genes encoding the putative nickel importer NikABCDE and, moreover, NikR binds directly to a specific DNA sequence within the promoter region of nikA in a metal-dependent manner to control gene expression...
July 31, 2018: Microbiology
Silvia Beurmann, Blake Ushijima, Patrick Videau, Christina M Svoboda, Apaala Chatterjee, Greta S Aeby, Sean M Callahan
Coral diseases contribute to the decline of coral reefs globally and threaten the health and future of coral reef communities. Acute Montipora white syndrome (aMWS) is a tissue loss disease that has led to the mortality of hundreds of Montipora capitata colonies in Kāne'ohe Bay, Hawai'i in recent years. This study describes the analysis of coral-associated bacterial communities using high-throughput sequencing generated by the PacBio RSII platform. Samples from three health states of M. capitata (healthy, healthy-diseased and diseased) were collected during an ongoing aMWS outbreak and a non-outbreak period and the bacterial communities were identified to determine whether a shift in community structure had occurred between the two periods...
July 27, 2018: Microbiology
Sharon J Peacock, Julian Parkhill, Nicholas M Brown
The current paradigm for hospital outbreak detection and investigation is based on methodology first developed over 150 years ago. Daily surveillance to detect patients positive for pathogens of particular importance for nosocomial infection is supported by epidemiological investigation to determine their relationship in time and place, and to identify any other factor that could link them. The antibiotic resistance pattern is commonly used as a surrogate for bacterial relatedness, although this lacks sensitivity and specificity...
July 27, 2018: Microbiology
Francesca Borsetti, Fabrizio Dal Piaz, Federico D'Alessio, Alessandra Stefan, Renato Brandimarti, Anindita Sarkar, Ankona Datta, Alejandro Montón Silva, Tanneke den Blaauwen, Mucchi Alberto, Enzo Spisni, Alejandro Hochkoeppler
To understand the effects triggered by Mn2+ on Deinococcus radiodurans, the proteome patterns associated with different growth phases were investigated. In particular, under physiological conditions we tested the growth rate and the biomass yield of D. radiodurans cultured in rich medium supplemented or not with MnCl2. The addition of 2.5-5.0 µM MnCl2 to the medium neither altered the growth rate nor the lag phase, but significantly increased the biomass yield. When higher MnCl2 concentrations were used (10-250 µM), biomass was again found to be positively affected, although we did observe a concentration-dependent lag phase increase...
July 27, 2018: Microbiology
Grith Miriam Maigaard Hermansen, Morten Lindqvist Hansen, Seyed Mohammad Hossein Khademi, Lars Jelsbak
Regulating intracellular levels of biological metal ions is essential for all bacterial species, as they are needed for virulence and a range of metabolic processes. Zinc is the second most abundant metal ion in Pseudomonas aeruginosa, but little is known about its regulation. Recent studies have identified a novel operon, zrmABCD (also called cntOLMI), encoding a metallophore system (pseudopaline) involved in zinc acquisition. Expression of this operon has been implicated in human infections and is regulated by the transcriptional regulator Zur (Zn2+ uptake regulator)...
July 3, 2018: Microbiology
Karukriti Kaushik Ghosh, Aman Prakash, Prateek Shrivastav, Vinayagamurthy Balamurugan, Manish Kumar
The outer membrane proteins of the pathogen are targeted to understand host-pathogen interactions and are central to the development of diagnostics. We report that Leptospira interrogans serovar Copenhageni strain Fiocruz L1-130 contains a gene LIC13341 that encodes a conserved outer membrane/periplasmic lipoprotein. The gene LIC13341 was cloned into expression vector pET28a and the recombinant LIC13341 (r-LIC13341) protein was purified from Escherichia coli BL21 (DE3) using affinity chromatography. The secondary structure of the purified r-LIC13341 protein featured a typical β-strand when observed by circular dichroism spectroscopy...
July 3, 2018: Microbiology
Amy Switzer, Dimitrios Evangelopoulos, Rita Figueira, Luiz Pedro S de Carvalho, Daniel R Brown, Sivaramesh Wigneshweraraj
The initial adaptive transcriptional response to nitrogen (N) starvation in Escherichia coli involves large-scale alterations to the transcriptome mediated by the transcriptional activator, NtrC. One of these NtrC-activated genes is yeaG, which encodes a conserved bacterial kinase. Although it is known that YeaG is required for optimal survival under sustained N starvation, the molecular basis by which YeaG benefits N starved E. coli remains elusive. By combining transcriptomics with targeted metabolomics analyses, we demonstrate that the methionine biosynthesis pathway becomes transcriptionally dysregulated in ΔyeaG bacteria experiencing sustained N starvation...
June 29, 2018: Microbiology
José Paulo Sampaio
Saccharomyces eubayanus was described less than 10 years ago and its discovery settled the long-lasting debate on the origins of the cold-tolerant yeast responsible for lager beer fermentation. The largest share of the genetic diversity of S. eubayanus is located in South America, and strains of this species have not yet been found in Europe. One or more hybridization events between S. eubayanus and S. cerevisiae ale beer strains gave rise to S. pastorianus, the allopolyploid yeasts responsible for lager beer production worldwide...
September 2018: Microbiology
Liliana Losada, April A Shea, David DeShazer
Burkholderia pseudomallei, the aetiological agent of melioidosis, is an inhabitant of soil and water in many tropical and subtropical regions worldwide. It possesses six distinct type VI secretion systems (T6SS-1 to T6SS-6), but little is known about most of them, as they are poorly expressed in laboratory culture media. A genetic screen was devised to locate a putative repressor of the T6SS-2 gene cluster and a MarR family transcriptional regulator, termed TctR, was identified. The inactivation of tctR resulted in a 50-fold increase in the expression of an hcp2-lacZ transcriptional fusion, indicating that TctR is a negative regulator of the T6SS-2 gene cluster...
September 2018: Microbiology
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