Microbial metabolism of isoprene: a much-neglected climate-active gas.
We describe the development and use of molecular methods to identify, quantify and genetically characterize isoprene-degrading strains in environmental samples. Finally, this review identifies research imperatives for the further study of the environmental impact, ecology, regulation and biochemistry of this interesting group of microbes. PMID: 32441612 [PubMed - as supplied by publisher] (Source: Microbiology)
Source: Microbiology - May 22, 2020 Category: Microbiology Authors: Murrell JC, McGenity TJ, Crombie AT Tags: Microbiology Source Type: research

High persister cell formation by clinical Staphylococcus aureus strains belonging to clonal complex 30.
Abstract Bacterial persisters form a subpopulation of cells that survive lethal concentrations of antibiotics without being genetically different from the susceptible population. They are generally considered to be phenotypic variants that spontaneously have entered a dormant state with low ATP levels or reduced membrane potential. In Staphylococcus aureus, a serious opportunistic human pathogen, persisters are believed to contribute to chronic infections that are a major global healthcare problem. While S. aureus persisters have mostly been studied in laboratory strains, we have here investigated the ability of c...
Source: Microbiology - May 19, 2020 Category: Microbiology Authors: Liu L, Wang Y, Bojer MS, Andersen PS, Ingmer H Tags: Microbiology Source Type: research

Mycoplasma pneumoniae biofilms grown in vitro: traits associated with persistence and cytotoxicity.
Abstract The atypical bacterial pathogen Mycoplasma pneumoniae is a leading etiological agent of community-acquired pneumonia in humans; infections are often recalcitrant, recurrent and resistant to antibiotic treatment. These characteristics suggest a mechanism that facilitates long-term colonization in hosts. In an in vitro setting, M. pneumoniae forms biofilms that are unusual in that motility plays no more than a very limited role in their formation and development. Given the unusual nature of M. pneumoniae biofilms, open questions remain concerning phenotypes associated with persistence, such as what properti...
Source: Microbiology - May 18, 2020 Category: Microbiology Authors: Feng M, Schaff AC, Balish MF Tags: Microbiology Source Type: research

Nutrient-dependent morphological variability of Bacteroides thetaiotaomicron.
Abstract Unique morphologies can enable bacteria to survive in their native environment. Furthermore, many bacteria change their cell shape to adapt to different environmental conditions. For instance, some bacteria increase their surface area under carbon or nitrogen starvation. Bacteriodes thetaiotaomicron is an abundant human gut species; it efficiently degrades a number of carbohydrates and also supports the growth of other bacteria by breaking down complex polysaccharides. The gut provides a variable environment as nutrient availability is subject to the diet and health of the host, yet how gut bacteria adapt...
Source: Microbiology - May 14, 2020 Category: Microbiology Authors: Rangarajan AA, Koropatkin NM, Biteen JS Tags: Microbiology Source Type: research

Induction of clpP expression by cell-wall targeting antibiotics in Streptococcus mutans.
Abstract Streptococcus mutans is one of the major bacteria of the human oral cavity that is associated with dental caries. The pathogenicity of this bacterium is attributed to its ability to rapidly respond and adapt to the ever-changing conditions of the oral cavity. The major player in this adaptive response is ClpP, an intracellular protease involved in degradation of misfolded proteins during stress responses. S. mutans encodes a single clpP gene with an upstream region uniquely containing multiple tandem repeat sequences (RSs). Here, we explored expression of clpP with respect to various stresses and report s...
Source: Microbiology - May 14, 2020 Category: Microbiology Authors: Khara P, Biswas S, Biswas I Tags: Microbiology Source Type: research

Microbe Profile: Bacillus subtilis: model organism for cellular development, and industrial workhorse.
Abstract Bacillus subtilis is the best studied model organism of the Gram-positive lineage. It is naturally transformable and has an extremely powerful genetic toolbox. It is fast growing and easy to cultivate. It is an important industrial organism, being proficient at secreting proteins and making small fine chemicals, as well as acting as a plant growth promoter. It has been an important model system for studying biofilms. Finally, it makes endospores, which have provided an exceptionally fruitful system for studying various central problems of cellular development, including the generation of asymmetry, cell f...
Source: Microbiology - May 11, 2020 Category: Microbiology Authors: Errington J, Aart LTV Tags: Microbiology Source Type: research

AsnB is responsible for peptidoglycan precursor amidation in Clostridium difficile in the presence of vancomycin.
Abstract Clostridium difficile 630 possesses a cryptic but functional gene cluster vanG Cd homologous to the vanG operon of Enterococcus faecalis. Expression of vanG Cd in the presence of subinhibitory concentrations of vancomycin is accompanied by peptidoglycan amidation on the meso-DAP residue. In this paper, we report the presence of two potential asparagine synthetase genes named asnB and asnB2 in the C. difficile genome whose products were potentially involved in this peptidoglycan structure modification. We found that asnB expression was only induced when C. difficile was grown in the presence of vancomycin,...
Source: Microbiology - April 30, 2020 Category: Microbiology Authors: Ammam F, Patin D, Coullon H, Blanot D, Lambert T, Mengin-Lecreulx D, Candela T Tags: Microbiology Source Type: research

RRNPP-type quorum sensing affects solvent formation and sporulation in Clostridium acetobutylicum.
Abstract The strictly anaerobic bacterium Clostridium acetobutylicum is well known for its ability to convert sugars into organic acids and solvents, most notably the potential biofuel butanol. However, the regulation of its fermentation metabolism, in particular the shift from acid to solvent production, remains poorly understood. The aim of this study was to investigate whether cell-cell communication plays a role in controlling the timing of this shift or the extent of solvent formation. Analysis of the available C. acetobutylicum genome sequences revealed the presence of eight putative RRNPP-type quorum-sensin...
Source: Microbiology - April 28, 2020 Category: Microbiology Authors: Kotte AK, Severn O, Bean Z, Schwarz K, Minton NP, Winzer K Tags: Microbiology Source Type: research

A response regulator protein with antar domain, AvnR, in Acinetobacter baumannii ATCC 17978 impacts its virulence and amino acid metabolism.
In this study, we describe a novel response regulator protein, AvnR (A1S_2006) that regulates virulence-related traits in A. baumannii ATCC17978. Sequence analysis suggests that AvnR is a CheY-like response regulator and contains the RNA-binding ANTAR (AmiR and NasR transcription anti-termination regulators) domain. We show that AvnR plays a role in regulating biofilm formation (on glass and plastic surfaces), surface motility, adhesion to A549 cells as well as in nitrogen metabolism in A. baumannii. RNA-Seq analysis revealed that avnR deletion results in altered expression of more than 150 genes (116 upregulated and 42 do...
Source: Microbiology - April 23, 2020 Category: Microbiology Authors: De Silva PM, Patidar R, Graham CI, Brassinga AKC, Kumar A Tags: Microbiology Source Type: research

Microbial gas vesicles as nanotechnology tools: exploiting intracellular organelles for translational utility in biotechnology, medicine and the environment.
Abstract A range of bacteria and archaea produce gas vesicles as a means to facilitate flotation. These gas vesicles have been purified from a number of species and their applications in biotechnology and medicine are reviewed here. Halobacterium sp. NRC-1 gas vesicles have been engineered to display antigens from eukaryotic, bacterial and viral pathogens. The ability of these recombinant nanoparticles to generate an immune response has been quantified both in vitro and in vivo. These gas vesicles, along with those purified from Anabaena flos-aquae and Bacillus megaterium, have been developed as an acoustic report...
Source: Microbiology - April 22, 2020 Category: Microbiology Authors: Hill AM, Salmond GPC Tags: Microbiology Source Type: research

Expression of an alcohol dehydrogenase gene in a heterotrophic bacterium induces carbon dioxide-dependent high-yield growth under oligotrophic conditions.
Abstract Sphingobium japonicum strain UT26, whose γ-hexachlorocyclohexane-degrading ability has been studied in detail, is a typical aerobic and heterotrophic bacterium that needs organic carbon sources for its growth, and cannot grow on a minimal salt agar medium prepared without adding any organic carbon sources. Here, we isolated a mutant of UT26 with the ability to grow to visible state on such an oligotrophic medium from a transposon-induced mutant library. This high-yield growth under oligotrophic conditions (HYGO) phenotype was CO2-dependent and accompanied with CO2 incorporation. In the HYGO mutant, ...
Source: Microbiology - April 20, 2020 Category: Microbiology Authors: Inaba S, Sakai H, Kato H, Horiuchi T, Yano H, Ohtsubo Y, Tsuda M, Nagata Y Tags: Microbiology Source Type: research

MSMEG_2432 of Mycobacterium smegmatis mc2155 is a dual function enzyme that exhibits DD-carboxypeptidase and β-lactamase activities.
MSMEG_2432 of Mycobacterium smegmatis mc2155 is a dual function enzyme that exhibits DD-carboxypeptidase and β-lactamase activities. Microbiology. 2020 Apr 17;: Authors: Pandey SD, Jain D, Kumar N, Adhikary A, Kumar N G, Ghosh AS Abstract Mycobacterial peptidoglycan (PG) is an unsolved puzzle due to its complex structure and involvement of multiple enzymes in the process of its remodelling. dd-Carboxypeptidases are low molecular mass penicillin-binding proteins (LMM-PBPs) that catalyzes the cleavage of terminal d-Ala of muramyl pentapeptide branches and thereby helps in the PG remodelling process...
Source: Microbiology - April 17, 2020 Category: Microbiology Authors: Pandey SD, Jain D, Kumar N, Adhikary A, Kumar N G, Ghosh AS Tags: Microbiology Source Type: research

Identification of Photorhabdus symbionts by MALDI-TOF MS.
In this study, we evaluated the potential of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of Photorhabdus species. To this end, we established a collection of 54 isolates consisting of type strains and multiple field strains that belong to each of the validly described species and subspecies of this genus. Reference spectra for the strains were generated and used to complement a currently available database. The extended reference database was then used for identification based on the direct transfer sample preparation method and the protein fingerprint ...
Source: Microbiology - April 17, 2020 Category: Microbiology Authors: Hill V, Kuhnert P, Erb M, Machado RAR Tags: Microbiology Source Type: research

Multigenic engineering of the chloroplast genome in the green alga Chlamydomonas reinhardtii.
Abstract The chloroplast of microalgae such as Chlamydomonas reinhardtii represents an attractive chassis for light-driven production of novel recombinant proteins and metabolites. Methods for the introduction and expression of transgenes in the chloroplast genome (=plastome) of C. reinhardtii are well-established and over 100 different proteins have been successfully produced. However, in almost all reported cases the complexity of the genetic engineering is low, and typically involves introduction into the plastome of just a single transgene together with a selectable marker. In order to exploit fully the potent...
Source: Microbiology - April 6, 2020 Category: Microbiology Authors: Larrea-Alvarez M, Purton S Tags: Microbiology Source Type: research

Microbe Profile: Campylobacter jejuni - survival instincts.
Abstract Campylobacter jejuni is considered to be the most common bacterial cause of human gastroenteritis worldwide. C. jejuni can cause bloody diarrhoea, fever and abdominal pain in humans along with post-infectious sequelae such as Guillain-Barré syndrome (a paralytic autoimmune complication). C. jejuni infections can be fatal, particularly among young children. C. jejuni are distributed in most warm-blooded animals, and therefore the main route of transmission is generally foodborne, via the consumption and handling of meat products (particularly poultry). C. jejuni is microaerophilic and oxygen-sensiti...
Source: Microbiology - March 31, 2020 Category: Microbiology Authors: Gundogdu O, Wren BW Tags: Microbiology Source Type: research

Genetic regulation, biochemical properties and physiological importance of arginase from Sinorhizobium meliloti.
I, Dunn MF Abstract In bacteria, l-arginine is a precursor of various metabolites and can serve as a source of carbon and/or nitrogen. Arginine catabolism by arginase, which hydrolyzes arginine to l-ornithine and urea, is common in nature but has not been studied in symbiotic nitrogen-fixing rhizobia. The genome of the alfalfa microsymbiont Sinorhizobium meliloti 1021 has two genes annotated as arginases, argI1 (smc03091) and argI2 (sma1711). Biochemical assays with purified ArgI1 and ArgI2 (as 6His-Sumo-tagged proteins) showed that only ArgI1 had detectable arginase activity. A 1021 argI1 null mutant lacked argi...
Source: Microbiology - March 27, 2020 Category: Microbiology Authors: Ide AA, Hernández VM, Medina-Aparicio L, Carcamo-Noriega E, Girard L, Hernández-Lucas I, Dunn MF Tags: Microbiology Source Type: research

Microbiome diversity and composition varies across body areas in a freshwater turtle.
This study provides novel, baseline information about the external microbiomes of turtles and is a first step in understanding their ecological roles. PMID: 32213245 [PubMed - as supplied by publisher] (Source: Microbiology)
Source: Microbiology - March 26, 2020 Category: Microbiology Authors: McKnight DT, Zenger KR, Alford RA, Huerlimann R Tags: Microbiology Source Type: research

The role of MTHFDL in mediating intracellular lipogenesis in oleaginous Mortierella alpina.
Abstract The oleaginous fungus Mortierella alpina can synthesize a variety of polyunsaturated fatty acids, which are used extensively in industry for the production of arachidonic acid (AA). NADPH is the limiting factor and critical reducing agent in lipid biosynthesis. In the folate cycle, methylenetetrahydrofolate dehydrogenase (MTHFDL) catalyzes the conversion of methylene tetrahydrofolate into 10-formyl-tetrahydrofolate with the reduction of NADP+ to NADPH. MTHFDL RNAi was used to investigate the role of the folate cycle in lipogenesis. Gene knockdown decreased the transcript levels of MTHFDL by about 50 % a...
Source: Microbiology - March 25, 2020 Category: Microbiology Authors: Wang H, Wang Q, Zhang C, Chen H, Lu W, Gu Z, Zhao J, Zhang H, Chen YQ, Chen W Tags: Microbiology Source Type: research

Photorhabdus: a tale of contrasting interactions.
Abstract Different model systems have, over the years, contributed to our current understanding of the molecular mechanisms underpinning the various types of interaction between bacteria and their animal hosts. The genus Photorhabdus comprises Gram-negative insect pathogenic bacteria that are normally found as symbionts that colonize the gut of the infective juvenile stage of soil-dwelling nematodes from the family Heterorhabditis. The nematodes infect susceptible insects and release the bacteria into the insect haemolymph where the bacteria grow, resulting in the death of the insect. At this stage the nematodes f...
Source: Microbiology - March 25, 2020 Category: Microbiology Authors: Clarke DJ Tags: Microbiology Source Type: research

Characterization of the hemolytic activity of Riemerella anatipestifer.
In this study, 29 of 52 R. anatipestifer strains showed hemolytic activity on duck blood agar, whereas all the tested dba+ (with hemolytic activity on duck blood agar) and dba- strains created pores in the duck red blood cells, with 4.35-9.03% hemolytic activity in a liquid hemolysis assay after incubation for 24 h. The concentrated culture supernatants of all the tested R. anatipestifer strains and the extracted outer membrane proteins (OMPs) from dba+ R. anatipestifer strains showed hemolytic activity on duck blood agar. These results, together with the median lethal dose (LD50) of some dba+ and dba- R. anatipesti...
Source: Microbiology - March 11, 2020 Category: Microbiology Authors: Gong Y, Yang Y, Chen Y, Sun B, Xue Y, Xu X, Wang X, Islam N, Du X, Hu Q Tags: Microbiology Source Type: research

Salmonella Typhimurium encoded cold shock protein E is essential for motility and biofilm formation.
Abstract The ability of bacteria to form biofilms increases their survival under adverse environmental conditions. Biofilms have enormous medical and environmental impact; consequently, the factors that influence biofilm formation are an important area of study. In this investigation, the roles of two cold shock proteins (CSP) during biofilm formation were investigated in Salmonella Typhimurium, which is a major foodborne pathogen. Among all CSP transcripts studied, the expression of cspE (STM14_0732) was higher during biofilm growth. The cspE deletion strain (ΔcspE) did not form biofilms on a cholesterol co...
Source: Microbiology - March 11, 2020 Category: Microbiology Authors: Ray S, Da Costa R, Thakur S, Nandi D Tags: Microbiology Source Type: research

The need to unravel the twisted nature of the Borrelia burgdorferi sensu lato complex across Europe.
Abstract Lyme borreliosis is a vector-borne infection caused by bacteria under the Borrelia burgdorferi sensu lato complex, both in Europe and North America. Differential gene expression at different times throughout its infectious cycle allows the spirochete to survive very diverse environments within different mammalian hosts as well as the tick vector. To date, the vast majority of data about spirochetal proteins and their functions are from genetic studies carried out on North American strains of a single species, i.e. B. burgdorferi sensu stricto. The whole-genome sequences recently obtained for several Europ...
Source: Microbiology - March 3, 2020 Category: Microbiology Authors: Strnad M, Rego ROM Tags: Microbiology Source Type: research

Transient enhanced cell division by blocking DNA synthesis in Escherichia coli.
aacute;n EC Abstract Duplication of the bacterial nucleoid is necessary for cell division hence specific arrest of DNA replication inhibits divisions culminating in filamentation, nucleoid dispersion and appearance of a-nucleated cells. It is demonstrated here that during the first 10 min however, Escherichia coli enhanced residual divisions: the proportion of constricted cells doubled (to 40%), nucleoids contracted and cells remodelled dimensions: length decreased and width increased. The preliminary data provides further support to the existence of temporal and spatial couplings between the nucleoid/repli...
Source: Microbiology - March 2, 2020 Category: Microbiology Authors: Martín CM, Zaritsky A, Fishov I, Guzmán EC Tags: Microbiology Source Type: research

A genuine mycobacterial thermophile: Mycobacterium hassiacum growth, survival and GpgS stability at near-pasteurization temperatures.
Abstract Mycobacterium hassiacum is so far the most thermophilic among mycobacteria as it grows optimally at 50 °C and up to 65 °C in a glycerol-based medium, as verified in this study. Since this and other nontuberculous mycobacteria (NTM) thrive in diverse natural and artificial environments, from where they may access and infect humans, we deemed essential to probe M. hassiacum resistance to heat, a strategy routinely used to control microbial growth in water-supply systems, as well as in the food and drink industries. In addition to possibly being a threat in its own right in rare occasio...
Source: Microbiology - February 25, 2020 Category: Microbiology Authors: Alarico S, Nunes-Costa D, Silva A, Costa M, Macedo-Ribeiro S, Empadinhas N Tags: Microbiology Source Type: research

Genomic diversity of Salmonella enterica isolated from papaya samples collected during multiple outbreaks in 2017.
Abstract In 2017, the US Food and Drug Administration investigated the sources of multiple outbreaks of salmonellosis. Epidemiologic and traceback investigations identified Maradol papayas as the suspect vehicles. During the investigations, the genomes of 55 Salmonella enterica that were isolated from papaya samples were sequenced. Serovar assignments and phylogenetic analysis placed the 55 isolates into ten distinct groups, each representing a different serovar. Within-serovar SNP differences are generally between 0 and 20 SNPs, while the median between-serovar distance is 51 812 SNPs. We observed two groups wi...
Source: Microbiology - February 20, 2020 Category: Microbiology Authors: Pightling AW, Pettengill J, Luo Y, Strain E, Rand H Tags: Microbiology Source Type: research

Candida albicans increases the pathogenicity of Staphylococcus aureus during polymicrobial infection of Galleria mellonella larvae.
This study detailed the responses of Galleria mellonella larvae to disseminated infection caused by co-infection with Candida albicans and Staphylococcus aureus. Doses of C. albicans (1×105 larva-1) and S. aureus (1×104 larva-1) were non-lethal in mono-infection but when combined significantly (P
Source: Microbiology - February 18, 2020 Category: Microbiology Authors: Sheehan G, Tully L, Kavanagh KA Tags: Microbiology Source Type: research

Conditional requirement of SglT for type IV pili function and S-motility in Myxococcus xanthus.
Abstract Myxobacteria exhibit complex social behaviors such as predation, outer membrane exchange and fruiting body formation. These behaviors depend on coordinated movements of cells on solid surfaces that involve social (S) motility. S-motility is powered by extension-retraction cycles of type 4 pili (Tfp) and exopolysaccharides (EPS) that provide a matrix for group cellular movement. Here, we characterized a new class of S-motility mutants in Myxococcus xanthus. These mutants have a distinctive phenotype: they lack S-motility even though they produce pili and EPS and the phenotype is temperature-sensitive. The ...
Source: Microbiology - February 10, 2020 Category: Microbiology Authors: Troselj V, Pathak DT, Wall D Tags: Microbiology Source Type: research

Effect of four kinds of complexing iron on the process of iron uptake by Anabaena flos-aquae.
This study aimed to investigate the absorption process of four kinds of complexing iron absorbed by Anabaena flos-aquae. Results showed that the absorptive capacity of A. flos-aquae to complex iron was inversely proportional to the stability of the complex bond of complex iron. Complex iron with weak binding ability can be quickly adsorbed by A. flos-aquae. The absorptive rate was as follows: ferric humate, ferric oxalate>ammonium ferric citrate>EDTA Fe. For EDTA-Fe with a strong binding ability, a moderate iron concentration (e.g. 0.6 mg l-1) is favourable for iron uptake by A. flos-aquae. Our e...
Source: Microbiology - February 5, 2020 Category: Microbiology Authors: Qiu Y, Wang Z, Huang Z, Liu F, Tang D, Liu J Tags: Microbiology Source Type: research

Molecular mechanism of sulfur chemolithotrophy in the betaproteobacterium Pusillimonas ginsengisoli SBSA.
Abstract Chemolithotrophic sulfur oxidation represents a significant part of the biogeochemical cycling of this element. Due to its long evolutionary history, this ancient metabolism is well known for its extensive mechanistic and phylogenetic diversification across a diverse taxonomic spectrum. Here we carried out whole-genome sequencing and analysis of a new betaproteobacterial isolate, Pusillimonas ginsengisoli SBSA, which is found to oxidize thiosulfate via the formation of tetrathionate as an intermediate. The 4.7 Mb SBSA genome was found to encompass a soxCDYZAXOB operon, plus single thiosulfate dehyd...
Source: Microbiology - January 30, 2020 Category: Microbiology Authors: Mandal S, Rameez MJ, Chatterjee S, Sarkar J, Pyne P, Bhattacharya S, Shaw R, Ghosh W Tags: Microbiology Source Type: research

Adaptation to pH stress by Vibrio fischeri can affect its symbiosis with the Hawaiian bobtail squid (Euprymna scolopes).
Abstract Many microorganisms engaged in host-microbe interactions pendulate between a free-living phase and a host-affiliated stage. How adaptation to stress during the free-living phase affects host-microbe associations is unclear and understudied. To explore this topic, the symbiosis between Hawaiian bobtail squid (Euprymna scolopes) and the luminous bacterium Vibrio fischeri was leveraged for a microbial experimental evolution study. V. fischeri experienced adaptation to extreme pH while apart from the squid host. V. fischeri was serially passaged for 2000 generations to the lower and upper pH growth limits for...
Source: Microbiology - January 22, 2020 Category: Microbiology Authors: Cohen ML, Mashanova EV, Jagannathan SV, Soto W Tags: Microbiology Source Type: research

'Community evolution' - laboratory strains and pedigrees in the age of genomics.
Abstract Molecular microbiologists depend heavily on laboratory strains of bacteria, which are ubiquitous across the community of research groups working on a common organism. However, this presumes that strains present in different laboratories are in fact identical. Work on a culture of Vibrio cholerae preserved from 1916 provoked us to consider recent studies, which have used both classical genetics and next-generation sequencing to study the heterogeneity of laboratory strains. Here, we review and discuss mutations and phenotypic variation in supposedlyisogenic reference strains of V. cholerae and Escherichia ...
Source: Microbiology - January 20, 2020 Category: Microbiology Authors: Dorman MJ, Thomson NR Tags: Microbiology Source Type: research

Polyamines produced by Sinorhizobium meliloti Rm8530 contribute to symbiotically relevant phenotypes ex planta and to nodulation efficiency on alfalfa.
nn MF Abstract In nitrogen-fixing rhizobia, emerging evidence shows significant roles for polyamines in growth and abiotic stress resistance. In this work we show that a polyamine-deficient ornithine decarboxylase null mutant (odc2) derived from Sinorhizobium meliloti Rm8530 had significant phenotypic differences from the wild-type, including greatly reduced production of exopolysaccharides (EPS; ostensibly both succinoglycan and galactoglucan), increased sensitivity to oxidative stress and decreased swimming motility. The introduction of the odc2 gene borne on a plasmid into the odc2 mutant restored wild-type phe...
Source: Microbiology - January 14, 2020 Category: Microbiology Authors: Becerra-Rivera VA, Arteaga A, Leija A, Hernández G, Dunn MF Tags: Microbiology Source Type: research

Antibiofilm activity in the culture supernatant of a marine Pseudomonas sp. bacterium.
te; S Abstract In the marine environment, most solid surfaces are covered by microbial biofilms, mainly composed of bacteria and diatoms. The negative effects of biofilms on materials and equipment are numerous and pose a major problem for industry and human activities. Since marine micro-organisms are an important source of bioactive metabolites, it is possible that they synthesize natural ecofriendly molecules that inhibit the adhesion of organisms. In this work, the antibiofilm potential of marine bacteria was investigated using Flavobacterium sp. II2003 as a target. This strain is potentially a pioneer strain ...
Source: Microbiology - January 14, 2020 Category: Microbiology Authors: Doghri I, Brian-Jaisson F, Graber M, Bazire A, Dufour A, Bellon-Fontaine MN, Herry JM, Ferro AC, Sopena V, Lanneluc I, Sablé S Tags: Microbiology Source Type: research

Defining the requirements for the conjugative transfer of Rhizobium leguminosarum plasmid pRleVF39b.
Abstract Rhizobium leguminosarum strain VF39 contains a plasmid, pRleVF39b, which encodes a distinctive type of conjugation system (rhizobial type IVa) that is relatively widespread among rhizobial genomes. The cluster of genes encoding the transfer functions lacks orthologs to genes such as traCD, traF and traB, but contains 15 conserved genes of unknown function. We determined the importance of these genes in conjugation by constructing marked and unmarked mutations in each gene, and established that six genes, now designated trcA-F, played a significant role in plasmid transfer. Like the relaxase gene, traA, an...
Source: Microbiology - January 14, 2020 Category: Microbiology Authors: Wathugala ND, Hemananda KM, Yip CB, Hynes MF Tags: Microbiology Source Type: research

Peptides encoded in the Streptococcus M utans RcrRPQ operon are essential for thermotolerance.
Abstract The MarR-like transcriptional regulator and two ABC transporters encoded by the rcrRPQ operon in the dental caries pathogen Streptococcus mutans have important regulatory roles related to oxidative stress tolerance, genetic competence and (p)ppGpp metabolism. A unique feature of the rcrRPQ operon, when compared to other bacteria, is the presence of two peptides, designated Pep1 and Pep2, encoded in alternative reading frames at the 3' end of rcrQ. Here, we show that the rcrRPQ operon, including Pep1 and 2, is essential for S. mutans to survive and maintain viability at elevated temperatures. No major chan...
Source: Microbiology - January 10, 2020 Category: Microbiology Authors: Shields RC, Kim JN, Ahn SJ, Burne RA Tags: Microbiology Source Type: research

A new serine protease family with elastase activity is produced by Streptomyces bacteria.
Abstract We found an elastolytic activity in the culture supernatant of Streptomyces sp. P-3, and the corresponding enzyme (streptomycetes elastase, SEL) was purified to apparent homogeneity from the culture supernatant. The molecular mass of purified SEL was approximately 18 kDa as judged by SDS-PAGE analysis and gel-filtration chromatography. Utilizing information from N-terminal amino acid sequencing of SEL and mass spectrometry of SEL tryptic fragments, we succeeded in cloning the gene-encoding SEL. The cloned SEL gene contains a 726 bp ORF, which encodes a 241 amino acid polypeptide containing a putative sign...
Source: Microbiology - January 2, 2020 Category: Microbiology Authors: Fujii T, Fukano K, Hirano K, Mimura A, Terauchi M, Etoh SI, Iida A Tags: Microbiology Source Type: research

A structure-function analysis of interspecies antagonism by the 2-heptyl-4-alkyl-quinolone signal molecule from Pseudomonas aeruginosa.
Abstract In recent years, the alkyl-quinolone molecular framework has already provided a rich source of bioactivity for the development of novel anti-infective compounds. Based on the quorum-sensing signalling molecules 4-hydroxy-2-heptylquinoline (HHQ) and 3,4-dihydroxy-2-heptylquinoline (PQS) from the nosocomial pathogen Pseudomonas aeruginosa, modifications have been developed with markedly enhanced anti-biofilm bioactivity towards important fungal and bacterial pathogens, including Candida albicans and Aspergillus fumigatus. Here we show that antibacterial activity of HHQ against Vibrionaceae is species-specif...
Source: Microbiology - December 20, 2019 Category: Microbiology Authors: Ramos AF, Woods DF, Shanahan R, Cano R, McGlacken GP, Serra C, O'Gara F, Reen FJ Tags: Microbiology Source Type: research

Prediction of novel non-coding RNAs relevant for the growth of Pseudomonas putida in a bioreactor.
as SC Abstract Pseudomonas putida is a micro-organism with great potential for industry due to its stress-endurance traits and easy manipulation of the metabolism. However, optimization is still required to improve production yields. In the last years, manipulation of bacterial small non-coding RNAs (ncRNAs) has been recognized as an effective tool to improve the production of industrial compounds. So far, very few ncRNAs are annotated in P. putida beyond the generally conserved. In the present study, P. putida was cultivated in a two-compartment scale-down bioreactor that simulates large-scale industrial bioreact...
Source: Microbiology - December 20, 2019 Category: Microbiology Authors: Pobre V, Graça-Lopes G, Saramago M, Ankenbauer A, Takors R, Arraiano CM, Viegas SC Tags: Microbiology Source Type: research

SufT is required for growth of Mycobacterium smegmatis under iron limiting conditions.
This study used targeted gene deletion to investigate the role of SufT in the physiology of mycobacteria, using Mycobacterium smegmatis as a model organism. Deletion of the sufT gene in M. smegmatis had no impact on growth under standard culture conditions and did not significantly alter activity of the FeS cluster dependent enzymes succinate dehydrogenase (SDH) and aconitase (ACN). Furthermore, the ΔsufT mutant was no more sensitive than the wild-type strain to the redox cycler 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), or the anti-tuberculosis drugs isoniazid, clofazimine or rifampicin. In contrast, the ΔsufT m...
Source: Microbiology - December 20, 2019 Category: Microbiology Authors: Tamuhla T, Joubert L, Willemse D, Williams MJ Tags: Microbiology Source Type: research

Ambient pH regulates secretion of lipases in Malassezia furfur.
In this study, we investigated the impact of ambient pH on physiology and expression of lipases in M. furfur grown under different pH conditions. The yeast was able to grow in media ranging from pH 4 to 10 without morphological alteration. Elevation in pH value enhanced the extracellular lipase activity but decreased that of intracellular lipase. The qPCR results revealed that a set of functional lipase genes, LIP3-6, were constitutively expressed regardless of pH conditions or exposure time. Based on the data, we conclude that the external pH plays a promotional role in the secretion of lipases but exerts less effect on t...
Source: Microbiology - December 20, 2019 Category: Microbiology Authors: Juntachai W, Chaichompoo A, Chanarat S Tags: Microbiology Source Type: research

Metabolic networks of the human gut microbiota.
, Frank JGM, Furze E, Garner R, Gibbs V, Goldberg-Hall R, Goldman CJ, Goltsios FF, Gorjipour K, Grant T, Greco B, Guliyev N, Habrich A, Hyland H, Ibrahim N, Iozzo T, Jawaheer-Fenaoui A, Jaworski JJ, Jhajj MK, Jones J, Joyette R, Kaudeer S, Kelley S, Kiani S, Koayes M, Kpata AJAL, Maingot S, Martin S, Mathers K, McCullogh S, McNamara K, Mendonca J, Mohammad K, Momtaz SA, Navaratnarajah T, Nguyen-Duong K, Omran M, Ortiz A, Patel A, Paul-Cole K, Plaisir PA, Porras Marroquin JA, Prevost A, Quach A, Rafal AJ, Ramsarun R, Rhnima S, Rili L, Safir N, Samson E, Sandiford RR, Secondi S, Shahid S, Shahroozi M, Sidibé F, Smith ...
Source: Microbiology - December 4, 2019 Category: Microbiology Authors: Selber-Hnatiw S, Sultana T, Tse W, Abdollahi N, Abdullah S, Al Rahbani J, Alazar D, Alrumhein NJ, Aprikian S, Arshad R, Azuelos JD, Bernadotte D, Beswick N, Chazbey H, Church K, Ciubotaru E, D'Amato L, Del Corpo T, Deng J, Di Giulio BL, Diveeva D, Elahie Tags: Microbiology Source Type: research

Novel intermicrobial molecular interaction: Pseudomonas aeruginosa Quinolone Signal (PQS) modulates Aspergillus fumigatus response to iron.
ns DA Abstract Pseudomonas aeruginosa (Pa) and Aspergillus fumigatus (Af), the commonest bacterium and fungus in compromised host airways, compete for iron (Fe). The Pseudomonas quinolone signal (PQS), a Pa quorum sensing molecule, also chelates Fe, and delivers Fe to the Pa cell membrane using Pa siderophores. In models of Af biofilm formation or preformed biofilms, PQS inhibited Af in a low Fe environment. AfΔsidA (mutant unable to produce siderophores) biofilm was more sensitive to PQS inhibition than wild-type (WT), as was planktonic AfΔsidA growth. PQS decreased WT Af growth on agar. All these inh...
Source: Microbiology - November 28, 2019 Category: Microbiology Authors: Nazik H, Sass G, Ansari SR, Ertekin R, Haas H, Déziel E, Stevens DA Tags: Microbiology Source Type: research

Reductive tricarboxylic acid cycle enzymes and reductive amino acid synthesis pathways contribute to electron balance in a Rhodospirillum rubrum Calvin-cycle mutant.
Abstract Purple non-sulfur bacteria (PNSB) use light for energy and organic substrates for carbon and electrons when growing photoheterotrophically. This lifestyle generates more reduced electron carriers than are required for biosynthesis, even during consumption of some of the most oxidized organic substrates like malate and fumarate. Reduced electron carriers not used in biosynthesis must still be oxidized for photoheterotrophic growth to occur. Diverse PNSB commonly rely on the CO2-fixing Calvin cycle to oxidize reduced electron carriers. Some PNSB also produce H2 or reduce terminal electron acceptors as alter...
Source: Microbiology - November 27, 2019 Category: Microbiology Authors: McCully AL, Onyeziri MC, LaSarre B, Gliessman JR, McKinlay JB Tags: Microbiology Source Type: research

Mycobacterium smegmatis moxifloxacin persister cells produce high levels of hydroxyl radical, generating genetic resisters selectable not only with moxifloxacin, but also with ethambutol and isoniazid.
Abstract Bacterial antibiotic persister cells tolerate lethal concentrations of antibiotics but emerge as the antibiotic-sensitive population upon antibiotics withdrawal. However, the possibility of antibiotic-resistant genetic mutants emerging from the antibiotic persister population in the continued exposure to microbicidal concentrations of antibiotics needed investigation. We explored this possibility using the fast-growing Mycobacterium smegmatis as a model organism for Mycobacterium tuberculosis biology, as it is known to incur antibiotic-resistant mutations identical to and at identical target positions as ...
Source: Microbiology - November 20, 2019 Category: Microbiology Authors: Swaminath S, Paul A, Pradhan A, Sebastian J, Nair RR, Ajitkumar P Tags: Microbiology Source Type: research

Mitogen-activated protein kinase regulation of the phosphodiesterase RegA in early Dictyostelium development.
Abstract Mitogen-activated protein kinase (MAPK) regulation of cAMP-specific phosphodiesterase function has been demonstrated in mammalian cells and suspected to occur in other eukaryotes. Epistasis analysis in the soil amoeba Dictyostelium discoideum suggests the atypical MAPK Erk2 downregulates the function of the cAMP-specific phosphodiesterase RegA to regulate progression of the developmental life cycle. A putative MAPK docking motif located near a predicted MAPK phosphorylation site was characterized for contributions to RegA function and binding to Erk2 because a similar docking motif has been previously cha...
Source: Microbiology - November 15, 2019 Category: Microbiology Authors: Adhikari N, Kuburich NA, Hadwiger JA Tags: Microbiology Source Type: research

Stability of the Salmonella Typhimurium rcsC11 mutant under different stress conditions.
Abstract The virulence genes of Salmonella are modulated during infection by several regulatory systems, and the RcsCDB system is one of the most important of these. The S. Typhimurium EG14873 (rcsC11) strain harbours the rcsC11 point mutation, displaying a constitutive activation of this system, which is characterized by mucoid colonies and attenuated virulence phenotypes. In this work, the stability of the rcsC11 mutation was analysed under stress conditions. Under acid and anaerobic stresses, we observed the appearance of small and non-mucoid colonies of the rcsC11 strain. The sequencing of the rcsC gene from t...
Source: Microbiology - November 12, 2019 Category: Microbiology Authors: Torres MA, Terraf MCL, Minahk CJ, Delgado MA Tags: Microbiology Source Type: research

Analysis of phylogenetic diversity and in vitro adherence characteristics of respiratory syncytial virus and Streptococcus pneumoniae clinical isolates obtained during pediatric respiratory co-infections.
This study did not identify any statistically significant trend in the strains of RSV and S. pneumoniae associated with co-infections. Furthermore, almost all isolates (22 of 23) showed significantly increased adherence to RSV-infected cells. The level of adherence did not appear to correlate with pneumococcal strain or sequence type, and isolates obtained from RSV-infected patients displayed a similar level of adherence as those from RSV-negative patients. The absence of particular S. pneumoniae or RSV strains associated with co-infection, together with the near ubiquitous presence of RSV-mediated adhesion throughout the ...
Source: Microbiology - November 12, 2019 Category: Microbiology Authors: Brealey JC, Sly PD, Young PR, Chappell KJ Tags: Microbiology Source Type: research

A corepressor participates in LexA-independent regulation of error-prone polymerases in Acinetobacter.
This study uncovered another regulator of the atypical DNA damage response of this genus, to help describe how this pathogen acquires drug resistance through its expression of the error-prone polymerases under DdrR and UmuDAb control. PMID: 31687925 [PubMed - as supplied by publisher] (Source: Microbiology)
Source: Microbiology - November 5, 2019 Category: Microbiology Authors: Peterson MA, Grice AN, Hare JM Tags: Microbiology Source Type: research

Engineering the PduT shell protein to modify the permeability of the 1,2-propanediol microcompartment of Salmonella.
In this study, we used site-directed mutagenesis of the PduT shell protein to remove its central iron-sulfur cluster and create openings (pores) in the shell of the Pdu MCP that have varied chemical properties. Subsequently, in vivo and in vitro studies were used to show that PduT-C38S and PduT-C38A variants increased the diffusion of 1,2-propanediol, propionaldehyde, NAD+ and NADH across the shell of the MCP. In contrast, PduT-C38I and PduT-C38W eliminated the iron-sulfur cluster without altering the permeability of the Pdu MCP, suggesting that the side-chains of C38I and C38W occluded the opening formed by removal of the...
Source: Microbiology - November 1, 2019 Category: Microbiology Authors: Chowdhury C, Bobik TA Tags: Microbiology Source Type: research

Microbiology revamps its scope.
PMID: 31674900 [PubMed - as supplied by publisher] (Source: Microbiology)
Source: Microbiology - November 1, 2019 Category: Microbiology Authors: Parish T Tags: Microbiology Source Type: research