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Kyle A Tipton, Marjan Farokhyfar, Philip N Rather
Colony opacity phase variation in Acinetobacter baumannii strain AB5075 is regulated by a reversible high-frequency switch. Transposon mutagenesis was used to generate mutations that decreased the opaque to translucent switch and a gene encoding a predicted periplasmic membrane fusion component of a resistance-nodulation-cell division (RND)-type efflux system was isolated. This gene was designated arpA and immediately downstream was a gene designated arpB that encodes a predicted membrane transporter of RND-type systems...
October 19, 2016: MicrobiologyOpen
Siavash Isazadeh, Shameem Jauffur, Dominic Frigon
Effect of ecological variables on community assembly of heterotrophic bacteria at eight full-scale and two pilot-scale activated sludge wastewater treatment plants (AS-WWTPs) were explored by pyrosequencing of 16S rRNA gene amplicons. In total, 39 samples covering a range of abiotic factors spread over space and time were analyzed. A core bacterial community of 24 families detected in at least six of the eight AS-WWTPs was defined. In addition to the core families, plant-specific families (observed at <50% AS-WWTPs) were found to be also important in the community structure...
October 19, 2016: MicrobiologyOpen
Adam P Rofe, Luther J Davis, Jean L Whittingham, Elizabeth C Latimer-Bowman, Anthony J Wilkinson, Paul R Pryor
Rhodococcus equi (R. equi) is an important pulmonary pathogen in foals that often leads to the death of the horse. The bacterium harbors a virulence plasmid that encodes numerous virulence-associated proteins (Vaps) including VapA that is essential for intracellular survival inside macrophages. However, little is known about the precise function of VapA. Here, we demonstrate that VapA causes perturbation to late endocytic organelles with swollen endolysosome organelles having reduced Cathepsin B activity and an accumulation of LBPA, LC3 and Rab7...
October 19, 2016: MicrobiologyOpen
Thomas V Vezeteu, Otilia Bobiş, Robin F A Moritz, Anja Buttstedt
Honeybee colonies (Apis mellifera) serve as attractive hosts for a variety of pathogens providing optimal temperatures, humidity, and an abundance of food. Thus, honeybees have to deal with pathogens throughout their lives and, even as larvae they are affected by severe brood diseases like the European Foulbrood caused by Melissococcus plutonius. Accordingly, it is highly adaptive that larval food jelly contains antibiotic compounds. However, although food jelly is primarily consumed by bee larvae, studies investigating the antibiotic effects of this jelly have largely concentrated on bacterial human diseases...
October 14, 2016: MicrobiologyOpen
Joelie V Zwick, Sarah Noble, Yasser K Ellaicy, Gabrielle Dierker Coe, Dylan J Hakey, Alyssa N King, Alex J Sadauskas, Melinda J Faulkner
Organisms growing aerobically generate reactive oxygen species such as hydrogen peroxide. These reactive oxygen molecules damage enzymes and DNA, potentially causing cell death. In response, Bacillus subtilis produces at least nine potential peroxide-scavenging enzymes; two belong to the alkylhydroperoxide reductase (Ahp) class of peroxidases. Here, we explore the role of one of these Ahp homologs, AhpA. While previous studies demonstrated that AhpA can scavenge peroxides and thus defend cells against peroxides, they did not clarify when during growth the cell produces AhpA...
September 28, 2016: MicrobiologyOpen
Ken Meerbergen, Maarten Van Geel, Michael Waud, Kris A Willems, Raf Dewil, Jan Van Impe, Lise Appels, Bart Lievens
It is assumed that microbial communities involved in the biological treatment of different wastewaters having a different chemical composition harbor different microbial populations which are specifically adapted to the environmental stresses encountered in these systems. Yet, little is known about the composition of these microbial communities. Therefore, the aim of this study was to assess the microbial community composition over two seasons (winter and summer) in activated sludge from well-operating textile wastewater treatment plants (WWTPs) in comparison with municipal WWTPs, and to explain observed differences by environmental variables...
September 25, 2016: MicrobiologyOpen
Chongsi Sun, Lili Geng, Meiling Wang, Gaoxiang Shao, Yongfeng Liu, Changlong Shu, Jie Zhang
Endophytic bacterial communities play a key role in promoting plant growth and combating plant diseases. However, little is known about their population dynamics in plant tissues and bulk soil, especially in transgenic crops. This study investigated the colonization of transgenic maize harboring the Bacillus thuringiensis (Bt) cry1Ah gene by Bacillus subtilis strain B916-gfp present in plant tissues and soil. Bt and nontransgenic maize were inoculated with B916-gfp by seed soaking, or root irrigation under both laboratory greenhouse and field conditions...
September 25, 2016: MicrobiologyOpen
Yujie Xiao, Huizhong Liu, Hailing Nie, Shan Xie, Xuesong Luo, Wenli Chen, Qiaoyun Huang
Flagella-mediated motility is an important capability of many bacteria to survive in nutrient-depleted and harsh environments. Decreasing the intracellular cyclic di-GMP (c-di-GMP) level by overexpression of phosphodiesterase BifA promotes flagellar-mediated motility and induces planktonic lifestyle in Pseudomonas. The mechanism that regulates expression of bifA gene was poorly studied. Here we showed that expression of BifA was partly controlled by flagellar sigma factor FliA (σ(28) ) in Pseudomonas putidaKT2440...
September 23, 2016: MicrobiologyOpen
Donatella Ottaviani, Francesco Mosca, Serena Chierichetti, Pietro Giorgio Tiscar, Francesca Leoni
The human food-borne pathogens Arcobacter butzleri and A. cryaerophilus have been frequently isolated from the intestinal tracts and fecal samples of different farm animals and, after excretion, these microorganisms can contaminate the environment, including the aquatic one. In this regard, A. butzleri and A. cryaerophilus have been detected in seawater and bivalves of coastal areas which are affected by fecal contamination. The capability of bivalve hemocytes to interact with bacteria has been proposed as the main factor inversely conditioning their persistence in the bivalve...
September 20, 2016: MicrobiologyOpen
Ayodeji O Falade, Uchechukwu U Nwodo, Benson C Iweriebor, Ezekiel Green, Leonard V Mabinya, Anthony I Okoh
Ligninolytic extracellular enzymes, including lignin peroxidase, are topical owing to their high redox potential and prospective industrial applications. The prospective applications of lignin peroxidase span through sectors such as biorefinery, textile, energy, bioremediation, cosmetology, and dermatology industries. The litany of potentials attributed to lignin peroxidase is occasioned by its versatility in the degradation of xenobiotics and compounds with both phenolic and non-phenolic constituents. Over the years, ligninolytic enzymes have been studied however; research on lignin peroxidase seems to have been lagging when compared to other ligninolytic enzymes which are extracellular in nature including laccase and manganese peroxidase...
September 7, 2016: MicrobiologyOpen
Kathryn L Naylor, Magdalena Widziolek, Stuart Hunt, Mary Conolly, Matthew Hicks, Prachi Stafford, Jan Potempa, Craig Murdoch, C W Ian Douglas, Graham P Stafford
Outer membrane protein A (OmpA) is a key outer membrane protein found in Gram-negative bacteria that contributes to several crucial processes in bacterial virulence. In Porphyromonas gingivalis, OmpA is predicted as a heterotrimer of OmpA1 and OmpA2 subunits encoded by adjacent genes. Here we describe the role of OmpA and its individual subunits in the interaction of P. gingivalis with oral cells. Using knockout mutagenesis, we show that OmpA2 plays a significant role in biofilm formation and interaction with human epithelial cells...
September 6, 2016: MicrobiologyOpen
Matthew E Jennings, Faith H Lessner, Elizabeth A Karr, Daniel J Lessner
Subunits Rpo3 and Rpb3/AC40 of RNA polymerase (RNAP) from many archaea and some eukaryotes, respectively, contain a ferredoxin-like domain (FLD) predicted to bind one or two [4Fe-4S] clusters postulated to play a role in regulating the assembly of RNAP. To test this hypothesis, the two [4Fe-4S] cluster Rpo3 from Methanosarcina acetivorans was modified to generate variants that lack the FLD or each [4Fe-4S] cluster. Viability of gene replacement mutants revealed that neither the FLD nor the ability of the FLD to bind either [4Fe-4S] cluster is essential...
August 25, 2016: MicrobiologyOpen
Weixia Gao, Fenghong Liu, Wei Zhang, Yufen Quan, Yulei Dang, Jun Feng, Yanyan Gu, Shufang Wang, Cunjiang Song, Chao Yang
Poly-γ-glutamic acid (γ-PGA) is an important natural biopolymer that is used widely in fields of foods, medicine, cosmetics, and agriculture. Several B. amyloliquefaciens LL3 mutants were constructed to improve γ-PGA synthesis via single or multiple marker-less in-frame deletions of four gene clusters (itu, bae, srf, and fen) encoding antibiotic substances. γ-PGA synthesis by the Δsrf mutant showed a slight increase (4.1 g/L) compared with that of the wild-type strain (3.3 g/L). The ΔituΔsrf mutant showed increased γ-PGA yield from 3...
August 18, 2016: MicrobiologyOpen
Qiuyan Shao, Jimmy T Trinh, Colby S McIntosh, Brita Christenson, Gábor Balázsi, Lanying Zeng
The infection of Escherichia coli cells by bacteriophage lambda results in bifurcated means of propagation, where the phage decides between the lytic and lysogenic pathways. Although traditionally thought to be mutually exclusive, increasing evidence suggests that this lysis-lysogeny decision is more complex than once believed, but exploring its intricacies requires an improved resolution of study. Here, with a newly developed fluorescent reporter system labeling single phage and E. coli DNAs, these two distinct pathways can be visualized by following the DNA movements in vivo...
August 17, 2016: MicrobiologyOpen
Qibiao Sun, Yaping Liu, Huatao Yuan, Bin Lian
Ectomycorrhizal fungi are an essential component of forest ecosystems, most of which can form edible and medical fruiting bodies. Although many studies have focused on the fructification of ectomycorrhizal fungi in phenology, the impact of environmental contamination, especially living garbage, on the formation of fruiting body is still unknown. A field investigation, combined with a high-throughput sequencing method, was used to study the effect of living garbage pollution on the fructification and hypogeous community structure of ectomycorrhizal fungi symbiosing with cedar (Cedrus deodara (Roxb...
August 11, 2016: MicrobiologyOpen
Lisa M Dann, Stephanie Rosales, Jody McKerral, James S Paterson, Renee J Smith, Thomas C Jeffries, Rod L Oliver, James G Mitchell
Viral communities are important for ecosystem function as they are involved in critical biogeochemical cycles and controlling host abundance. This study investigates riverine viral communities around a small rural town that influences local water inputs. Myoviridae, Siphoviridae, Phycodnaviridae, Mimiviridae, Herpesviridae, and Podoviridae were the most abundant families. Viral species upstream and downstream of the town were similar, with Synechoccocus phage, salinus, Prochlorococcus phage, Mimivirus A, and Human herpes 6A virus most abundant, contributing to 4...
August 9, 2016: MicrobiologyOpen
Daniela Numberger, Daniel P R Herlemann, Klaus Jürgens, Guido Dehnhardt, Heide Schulz-Vogt
The gut microbiota has many beneficial effects on host metabolism and health, and its composition is determined by numerous factors. It is also assumed that there was a co-evolution of mammals and the bacteria inhabiting their gut. Current knowledge of the mammalian gut microbiota mainly derives from studies on humans and terrestrial animals, whereas those on marine mammals are sparse. However, they could provide additional information on influencing factors, such as the role of diet and co-evolution with the host...
October 2016: MicrobiologyOpen
Camilla Oppegård, Morten Kjos, Jan-Willem Veening, Jon Nissen-Meyer, Tom Kristensen
Lactobacillus plantarum produces a number of antimicrobial peptides (bacteriocins) that mostly target closely related bacteria. Although bacteriocins are important for the ecology of these bacteria, very little is known about how the peptides target sensitive cells. In this work, a putative membrane protein receptor of the two-peptide bacteriocin plantaricin JK was identified by comparing Illumina sequence reads from plantaricin JK-resistant mutants to a crude assembly of the sensitive wild-type Weissella viridescens genome using the polymorphism discovery tool VAAL...
August 2016: MicrobiologyOpen
Serena Gastaldi, Michela Zamboni, Giulia Bolasco, Gianfranco Di Segni, Glauco P Tocchini-Valentini
The G protein-coupled receptors Ste2 and Ste3 bind α- and a-factor, respectively, in Saccharomyces cerevisiae. These receptors share a similar conformation, with seven transmembrane segments, three intracellular loops, a C-terminus tail, and three extracellular loops. However, the amino acid sequences of these two receptors bear no resemblance to each other. Coincidently the two ligands, α- and a-factor, have different sequences. Both receptors activate the same G protein. To identify amino acid residues that are important for signal transduction, the STE2 and STE3 genes were mutagenized by a random PCR-based method...
August 2016: MicrobiologyOpen
Gangzheng Wang, Xiantao Cao, Xiaolong Ma, Mengpei Guo, Changhao Liu, Lianlian Yan, Yinbing Bian
Lentinula edodes, one of the most important edible mushrooms in China, is affected heavily by the infection of green mold that overgrows mushroom mycelia. We collected the diseased samples from main L. edodes cultivation regions in China to characterize the pathogen and to study the effect of Trichoderma spp. on L. edodes species. We identified six Trichoderma species, that is, T. harzianum, T. atroviride, T. viride, T. pleuroticola, T. longibrachiatum, and T. oblongisporum based on the internal transcribed spacer or tef1-α sequences and morphology characteristics...
August 2016: MicrobiologyOpen
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