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Research in Microbiology

Hebin Liao, Xiaowu Zhong, Lei Xu, Qiang Ma, Yongjian Wang, Yan Cai, Xiaolan Guo
OxyR is an important regulatory protein that plays a key role in anti-oxygenation, and its deletion causes a special VBNC (Viable But Non-Culturable) state in many bacteria including Salmonella typhimurium. The S. typhimurium in the VBNC state can grow in LB broth but cannot grow on an LB plate unless its concentration is sufficiently high. However, the mechanism that reverses this state is not clear. In this study, conditioned media containing autoinducer collected from the wild type strain can restore the growth of low concentrations of the oxyR mutant strain on LB plates, and S...
November 7, 2018: Research in Microbiology
Tantan Gao, Mingzheng Ding, Ching-Hong Yang, Haiyan Fan, Yunrong Chai, Yan Li
The rhizosphere bacterium Bacillus cereus 905 is capable of promoting plant growth through effective colonization on plant roots. The sodA2-encoding manganese-containing superoxide dismutase (MnSOD2) is important for survival of B. cereus 905 in the wheat rhizosphere. However, the genes involved in regulating sodA2 expression and the mechanisms of rhizosphere colonization of B. cereus 905 are not well elucidated. In this study, we found that the deletion of the ptsH gene, which encodes the histidine-phosphorylatable protein (HPr), a component of the phosphotransferase system (PTS), causes a decrease of about 60% in the MnSOD2 expression...
November 2, 2018: Research in Microbiology
Catherine J Edward, Athanasios Kotsiopoulos, Susan T L Harrison
Leptospirillum ferriphilum is the dominant iron-oxidising bacterium in traditional microbial communities utilised in bioprocesses for gold recovery from sulfidic minerals. Ferrous iron oxidation activity and growth of unadapted and thiocyanate-adapted L. ferriphilum HT was studied in batch culture across increasing thiocyanate (SCN- ) concentrations in the range 0 - 2 mg/L to assess the feasibility of recycling remediated cyanidation wastewaters. Thiocyanate concentrations of 1 mg/L and 1.4 mg/L induced an inhibitory effect in the unadapted culture wherein ferrous iron oxidation rate and cell growth were compromised...
November 1, 2018: Research in Microbiology
Laurent Debarbieux, Patrick Forterre, Mart Krupovic, Mzia Kutateladze, David Prangishvili
No abstract text is available yet for this article.
October 31, 2018: Research in Microbiology
Tomas Hessler, Susan T L Harrison, Robert J Huddy
Biological sulphate reduction (BSR) is a promising low-cost treatment of acid rock drainage effluents. In this paper, the system performance and microbial ecology of a lactate supplemented BSR up-flow anaerobic packed bed reactor (UAPBR) are evaluated across reactor height and compared to a continuous stirred tank reactor (CSTR). The biomass concentrations of planktonic and biofilm communities were quantified and subsequently characterised by 16S rRNA gene amplicon sequencing. The defined microbial communities were shown to correlate with differing availability of lactate, volatile fatty acids produced from lactate degradation and sulphate concentration...
October 8, 2018: Research in Microbiology
Bo Zeng, Zhiwen Lai, Lijin Sun, Zhongbao Zhang, Jianhua Yang, Zaixin Li, Jie Lin, Zhi Zhang
Polycystic ovary syndrome (PCOS) is a complex endocrine and metabolic disorder that affects 9-21% of reproductive-aged women. Affected women frequently display obesity, insulin resistance, and inflammation. Altered gut microbial community has been reported in PCOS and obese PCOS patients. However, the profile of the gut microbial community in insulin resistant PCOS (IR-PCOS) patients still remains unknown. In this study, next-generation sequencing based on the 16S rRNA gene was used to compare the gut microbial composition of women with IR-PCOS (n = 9, PCOS with insulin resistance), NIR-PCOS (n = 8, PCOS alone) and healthy controls (n = 8, HC)...
October 4, 2018: Research in Microbiology
Shintaro Maeno, Akinobu Kajikawa, Leon Dicks, Akihito Endo
Fructophilic lactic acid bacteria (FLAB) are unique in the sense that they prefer D-fructose over D-glucose as main carbon source. If D-glucose is metabolised, electron acceptors are required and significant levels of acetate are produced. These bacteria are found in environments rich in D-fructose, such as flowers, fruits and the gastrointestinal tract of insects feeding on fructose-rich diets. Fructobacillus spp. are representatives of this unique group, and their fructophilic characteristics are well conserved...
October 3, 2018: Research in Microbiology
Alexandro Guterres, Jonathan Gonçalves, Elba Regina Sampaio de Lemos
Bartonellosis is an emerging serious diseases of zoonotic relevance caused by an expanding number of recently discovered species of Bartonella. Many studies use partial gltA gene sequencing as the method of choice for species attribution, and a plethora of studies have utilized only this gene to describe Bartonella diversity. We observe a lack of correspondence between the phylogenies constructed using the complete gltA gene sequences and the small gene fragment usually used in phylogenetic analyzes. Everything indicates that important changes occurred by using larger fragments...
September 12, 2018: Research in Microbiology
Anke Licht, Martin Bommer, Tobias Werther, Kristin Neumann, Carolin Hobe, Erwin Schneider
Canonical ATP-binding cassette import systems rely on extracellular substrate binding proteins (SBP) for function. In gram-negative bacteria, SBPs are usually freely diffusible in the periplasm and, where studied, exist in excess over their cognate transporters. However, in vitro studies with the maltose transporter of Escherichia coli (MalFGK2 ) have demonstrated that mechanistically one copy of its SBP (MalE) per transport complex is sufficient for activity. To address whether such a condition is physiologically relevant, we have characterized a homolog of the E...
September 4, 2018: Research in Microbiology
Zhongxin Luo, Shengjie Li, Kun Hou, Guodong Ji
In this study, the spatial and seasonal bacterioplankton community dynamics were investigated in the main channel of the Middle Route of the South-to-North Water Diversion Project (MRP) using Illumina HiSeq sequencing. Water samples were collected in spring and summer from south to north at eight water quality monitoring stations, respectively. The results showed that seasonal changes had a more pronounced effect on the bacterioplankton community compositions (BCCs) than spatial variation. The diversity analysis results indicated that samples of summer have more operational taxonomic units (OTUs), higher richness and diversity than those in spring...
September 1, 2018: Research in Microbiology
Paulina Aguirre, Karlo Guerrero, Aminael Sanchez-Rodriguez, Juan Carlos Gentina, Axel Schippers
The purpose of this study was to compare the efficacy of galactose and high initial ferrous iron concentrations as inducers for extracellular polymeric substances (EPS) production in planktonic cells of Leptospirillum ferrooxidans and to study cell attachment to a mineral surface in comparison to cells not exposed to such substances. L. ferrooxidans was successfully adapted to grow in a modified 9K medium at different concentrations of galactose (0.15, 0.25, 0.35%) and also at different initial ferrous iron concentrations (18, 27, 36 g/L), which are higher than 9K medium (9 g/L)...
September 1, 2018: Research in Microbiology
Li-Zhu Liu, Zhen-Yuan Nie, Yi Yang, Xuan Pan, Xu Xia, Yu-Hang Zhou, Jin-Lan Xia, Li-Juan Zhang, Xiang-Jun Zhen, Hong-Ying Yang
For the first time, synchrotron radiation (SR) -based carbon K-edge X-ray absorption near edge structure (XANES) spectroscopy in-situ characterization was conducted to evaluate the evolution of superficial (about 10 nm) organic components of extracellular polymeric substances (EPS) of thermoacidophilic archaeon Acidianus manzaensis YN-25 acclimated with different energy substrates (FeS2 , CuFeS2 , S0 , FeSO4 ). The atomic force microscopy (AFM) morphology scanning showed that the strain acclimated with different energy substrates varied a lot in EPS amount...
September 1, 2018: Research in Microbiology
Francisco Issotta, Ana Moya-Beltrán, Cristóbal Mena, Paulo C Covarrubias, Christian Thyssen, Sören Bellenberg, Wolfgang Sand, Raquel Quatrini, Mario Vera
The family Acidiferrobacteraceae (order Acidiferrobacterales) currently contains Gram negative, neutrophilic sulfur oxidizers such as Sulfuricaulis and Sulfurifustis, as well as acidophilic iron and sulfur oxidizers belonging to the Acidiferrobacter genus. The diversity and taxonomy of the genus Acidiferrobacter has remained poorly explored. Although several metagenome and bioleaching studies have identified its presence worldwide, only two strains, namely Acidiferrobacter thiooxydans DSM 2932T , and Acidiferrobacter spp...
August 22, 2018: Research in Microbiology
Paulo C Covarrubias, Ana Moya-Beltrán, Joaquin Atavales, Francisco Moya-Flores, Pablo S Tapia, Lillian G Acuña, Silvia Spinelli, Raquel Quatrini
General knowledge on the diversity and biology of microbial viruses infecting bacterial hosts from extreme acidic environments lags behind most other econiches. In this study, we analyse the AcaML1 virus occurrence in the taxon, its genetic composition and infective behaviour under standard acidic and SOS-inducing conditions to assess its integrity and functionality. Occurrence analysis in sequenced acidithiobacilli showed that AcaML1-like proviruses are confined to the mesothermophiles Acidithiobacillus caldus and Thermithiobacillus tepidarius...
August 20, 2018: Research in Microbiology
Ringo Schwabe, Marlene Kirstin Anke, Katarzyna Szymańska, Oliver Wiche, Dirk Tischler
The Actinobacterium Gordonia rubripertincta CWB2 (DSM 46758) produces hydroxamate-type siderophores (188 mg L-1 ) under iron limitation. Analytical reversed-phase HPLC allowed determining a single peak of ferric iron chelating compounds from culture broth which was confirmed by the Fe-CAS assay. Elution profile and its absorbance spectrum were similar to those of commercial (des)ferrioxamine B which was used as reference compound. This confirms previously made assumptions and shows for the first time that the genus Gordonia produces desferrioxamine-like siderophores...
August 20, 2018: Research in Microbiology
Klaas Martinus Pos
No abstract text is available yet for this article.
September 2018: Research in Microbiology
Aurélie Roth, Cedric Govaerts
The secondary transporter LmrP from Lactoccoccus lactis is a remarkable model to study the molecular basis of secondary multidrug transport. This review article addresses more than twenty years of research about transport activity, substrates range, conformational dynamics and mechanistic models of drug export for LmrP. Several studies have shown that the transporter alternates between inward-open and outward-open conformations and that the transition is regulated by the protonation state of key acidic residues and is further modulated by the lipid environment...
September 2018: Research in Microbiology
Martijn Zwama, Akihito Yamaguchi
The over-expression of multidrug efflux pumps belonging to the Resistance-Nodulation-Division (RND) superfamily is one of the main causes of multidrug-resistance (MDR) in Gram-negative pathogenic bacteria. AcrB is the most thoroughly studied RND transporter and has functioned as a model for our understanding of efflux-mediated MDR. This multidrug-exporter can recognize and transport a wide range of structurally unrelated compounds (including antibiotics, dyes, bile salts and detergents), while it shows a strict inhibitor specificity...
September 2018: Research in Microbiology
Arthur Neuberger, Dijun Du, Ben F Luisi
Efflux pumps are membrane proteins which contribute to multi-drug resistance. In Gram-negative bacteria, some of these pumps form complex tripartite assemblies in association with an outer membrane channel and a periplasmic membrane fusion protein. These tripartite machineries span both membranes and the periplasmic space, and they extrude from the bacterium chemically diverse toxic substrates. In this chapter, we summarise current understanding of the structural architecture, functionality, and regulation of tripartite multi-drug efflux assemblies...
September 2018: Research in Microbiology
Hiroshi Nikaido
Transporters of the RND superfamily are well-known as the major drug efflux pumps of Gram-negative bacteria. However, they are widespread in organisms ranging from Archaea to Eukaryotes, and perform diverse functions. This review gives a brief overview of these diverse members of the superfamily with emphasis on their structure and functions.
September 2018: Research in Microbiology
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