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Asset Tag: Bacteria

July 7, 2019

MALDI-TOF mass spectrometry enables a comprehensive and fast analysis of dynamics and qualities of stress responses of Lactobacillus paracasei subsp. paracasei F19.

Lactic acid bacteria (LAB) are widely used as starter cultures in the manufacture of foods. Upon preparation, these cultures undergo various stresses resulting in losses of survival and fitness. In order to find conditions for the subsequent identification of proteomic biomarkers and their exploitation for preconditioning of strains, we subjected Lactobacillus (Lb.) paracasei subsp. paracasei TMW 1.1434 (F19) to different stress qualities (osmotic stress, oxidative stress, temperature stress, pH stress and starvation stress). We analysed the dynamics of its stress responses based on the expression of stress proteins using MALDI-TOF mass spectrometry (MS), which has so far been used for species identification. Exploiting the methodology of accumulating protein expression profiles by MALDI-TOF MS followed by the statistical evaluation with cluster analysis and discriminant analysis of principle components (DAPC), it was possible to monitor the expression of low molecular weight stress proteins, identify a specific time point when the expression of stress proteins reached its maximum, and statistically differentiate types of adaptive responses into groups. Above the specific result for F19 and its stress response, these results demonstrate the discriminatory power of MALDI-TOF MS to characterize even dynamics of stress responses of bacteria and enable a knowledge-based focus on the laborious identification of biomarkers and stress proteins. To our knowledge, the implementation of MALDI-TOF MS protein profiling for the fast and comprehensive analysis of various stress responses is new to the field of bacterial stress responses. Consequently, we generally propose MALDI-TOF MS as an easy and quick method to characterize responses of microbes to different environmental conditions, to focus efforts of more elaborate approaches on time points and dynamics of stress responses.

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July 7, 2019

A novel plasmid, pSx1, harboring a new Tn1696 derivative from extensively drug-resistant Shewanella xiamenensis encoding OXA-416.

The whole genome sequencing of extensively drug-resistant Shewanella xiamenensis T17 isolated from hospital effluents in Algeria revealed the presence of a novel 268.4?kb plasmid designated pSx1, which carries several antibiotic-resistance genes in the novel Tn1696 derivative (Tn6297), in addition to the chromosomal blaOXA-48-like gene (blaOXA-416). The presence of the plasmid was confirmed by nuclease S1-PFGE analysis and transformation by electroporation into Escherichia coli DH10B. Tn6297 contains an In27 class 1 integron harboring the dfrA12-orfF-aadA2 array, msr(E) and mph(E) associated with IS26; a new efflux pump multidrug resistance composite transposon delimited by two ISEc29s; Tn-tet harboring tetR and tetA(C); a class 1 integron with the qacG gene cassette; qnrVC6 and dfrA23 associated with ISCR1; and a complex class 1 integron In4-like containing aacC1, aadA1, blaVEB-16, catA2, sul1?, cmlA9, tetR, tetA(G), aac(6′)-II, and blaPSE-1. Its mer operon carries merB, but lacks merC, in contrast to Tn1696 and Tn21. This study represents the first characterization of a multidrug-resistant transposon and multidrug resistance plasmid in Shewanella and is the first report of blaOXA-416 in Algeria, providing evidence that Shewanella spp. could be an important reservoir and vehicle for drug resistance genes.

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July 7, 2019

Novel methyltransferase recognition motif identified in Chania multitudinisentens RB-25(T) gen. nov., sp. nov.

DNA methylation, defined by the addition of a methyl group to adenine or cytosine bases in DNA catalyzed by DNA methyltransferases (MTases), is one of the most studied post-replicative DNA modification mechanism in bacteria (Roberts et al., 2003b). The three forms of nucleotide methylation identified to date are: N6-methyladenine(m6A), N4-methylcytosine (m4C), and 5-methylcytosine (m5C) (Gromova and Khoroshaev, 2003).

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July 7, 2019

Recent “omics” advances in Helicobacter pylori.

The development of high-throughput whole genome sequencing (WGS) technologies is changing the face of microbiology, facilitating the comparison of large numbers of genomes from different lineages of a same organism. Our aim was to review the main advances on Helicobacter pylori “omics” and to understand how this is improving our knowledge of the biology, diversity and pathogenesis of H. pylori. Since the first H. pylori isolate was sequenced in 1997, 510 genomes have been deposited in the NCBI archive, providing a basis for improved understanding of the epidemiology and evolution of this important pathogen. This review focuses on works published between April 2015 and March 2016. Helicobacter “omics” is already making an impact and is a growing research field. Ultimately these advances will be translated into a routine clinical laboratory setting in order to improve public health.© 2016 John Wiley & Sons Ltd.

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July 7, 2019

Persistence of a dominant bovine lineage of group B Streptococcus reveals genomic signatures of host adaptation.

Group B Streptococcus (GBS) is a host-generalist species, most notably causing disease in humans and cattle. However, the differential adaptation of GBS to its two main hosts, and the risk of animal to human infection remain poorly understood. Despite improvements in control measures across Europe, GBS is still one of the main causative agents of bovine mastitis in Portugal. Here, by whole-genome analysis of 150 bovine GBS isolates we discovered that a single CC61 clone is spreading throughout Portuguese herds since at least the early 1990s, having virtually replaced the previous GBS population. Mutations within an iron/manganese transporter were independently acquired by all of the CC61 isolates, underlining a key adaptive strategy to persist in the bovine host. Lateral transfer of bacteriocin production and antibiotic resistance genes also underscored the contribution of the microbial ecology and genetic pool within the bovine udder environment to the success of this clone. Compared to strains of human origin, GBS evolves twice as fast in bovines and undergoes recurrent pseudogenizations of human-adapted traits. Our work provides new insights into the potentially irreversible adaptation of GBS to the bovine environment. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

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July 7, 2019

Whole-genome characterization of epidemic Neisseria meningitidis serogroup C and resurgence of serogroup W, Niger, 2015.

In 2015, Niger reported the largest epidemic of Neisseria meningitidis serogroup C (NmC) meningitis in sub-Saharan Africa. The NmC epidemic coincided with serogroup W (NmW) cases during the epidemic season, resulting in a total of 9,367 meningococcal cases through June 2015. To clarify the phylogenetic association, genetic evolution, and antibiotic determinants of the meningococcal strains in Niger, we sequenced the genomes of 102 isolates from this epidemic, comprising 81 NmC and 21 NmW isolates. The genomes of 82 isolates were completed, and all 102 were included in the analysis. All NmC isolates had sequence type 10217, which caused the outbreaks in Nigeria during 2013-2014 and for which a clonal complex has not yet been defined. The NmC isolates from Niger were substantially different from other NmC isolates collected globally. All NmW isolates belonged to clonal complex 11 and were closely related to the isolates causing recent outbreaks in Africa.

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July 7, 2019

Function and phylogeny of bacterial butyryl coenzyme A: acetate transferases and their diversity in the proximal colon of swine.

Studying the host-associated butyrate-producing bacterial community is important, because butyrate is essential for colonic homeostasis and gut health. Previous research has identified the butyryl coenzyme A (CoA):acetate-CoA transferase (EC 2.3.8.3) as a gene of primary importance for butyrate production in intestinal ecosystems; however, this gene family (but) remains poorly defined. We developed tools for the analysis of butyrate-producing bacteria based on 12 putative but genes identified in the genomes of nine butyrate-producing bacteria obtained from the swine intestinal tract. Functional analyses revealed that eight of these genes had strong But enzyme activity. When but paralogues were found within a genome, only one gene per genome encoded strong activity, with the exception of one strain in which no gene encoded strong But activity. Degenerate primers were designed to amplify the functional but genes and were tested by amplifying environmental but sequences from DNA and RNA extracted from swine colonic contents. The results show diverse but sequences from swine-associated butyrate-producing bacteria, most of which clustered near functionally confirmed sequences. Here, we describe tools and a framework that allow the bacterial butyrate-producing community to be profiled in the context of animal health and disease.Butyrate is a compound produced by the microbiota in the intestinal tracts of animals. This compound is of critical importance for intestinal health, and yet studying its production by diverse intestinal bacteria is technically challenging. Here, we present an additional way to study the butyrate-producing community of bacteria using one degenerate primer set that selectively targets genes experimentally demonstrated to encode butyrate production. This work will enable researchers to more easily study this very important bacterial function that has implications for host health and resistance to disease. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

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July 7, 2019

Diversity of the tetracycline mobilome within a Chinese pig manure sample.

Tetracycline antibiotics are widely used in livestock, and tetracycline resistance genes (TRG) are frequently reported in the manure of farmed animals. However, the diversity of TRG-carrying transposons in manure has still been rarely investigated. Using a culture-free functional metagenomic procedure, combined with large-insert library construction and sequencing, bioinformatic analyses, and functional experiments, we identified 17 distinct TRGs in a single pig manure sample, including two new tet genes: tet(59), encoding a tetracycline efflux pump, and tet(W/N/W), encoding mosaic ribosomal protection. Our study also revealed six new TRG-carrying putative nonconjugative transposons: Tn5706-like transposon Tn6298, IS200/605-related transposon Tn6303, Tn3 family transposon Tn6299, and three ISCR2-related transposons, Tn62300, Tn62301, and Tn62302 IMPORTANCE: Fertilization of agricultural fields with animal manure is believed to play a major role in antibiotic resistance dissemination in the environment. There is growing concern for the possible spread of antibiotic resistance from the environment to humans since genetic resistance determinants may be located in transposons and other mobile genetic elements potentially transferable to pathogens. Among the various antibiotic resistance genes found in manure, tetracycline resistance genes (TRGs) are some of the most common. The present study provides a detailed snapshot of the tetracycline mobilome in a single pig manure sample, revealing an unappreciated diversity of TRGs and potential TRG mobility vectors. Our precise identification of the TRG-carrying units will enable us to investigate in more details their mobility effectiveness. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

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July 7, 2019

Transfer of the methicillin resistance genomic island among staphylococci by conjugation.

Methicillin resistance creates a major obstacle for treatment of Staphylococcus aureus infections. The resistance gene, mecA, is carried on a large (20 kb to?>?60 kb) genomic island, staphylococcal cassette chromosome mec (SCCmec), that excises from and inserts site-specifically into the staphylococcal chromosome. However, although SCCmec has been designated a mobile genetic element, a mechanism for its transfer has not been defined. Here we demonstrate the capture and conjugative transfer of excised SCCmec. SCCmec was captured on pGO400, a mupirocin-resistant derivative of the pGO1/pSK41 staphylococcal conjugative plasmid lineage, and pGO400::SCCmec (pRM27) was transferred by filter-mating into both homologous and heterologous S. aureus recipients representing a range of clonal complexes as well as S. epidermidis. The DNA sequence of pRM27 showed that SCCmec had been transferred in its entirety and that its capture had occurred by recombination between IS257/431 elements present on all SCCmec types and pGO1/pSK41 conjugative plasmids. The captured SCCmec excised from the plasmid and inserted site-specifically into the chromosomal att site of both an isogenic S. aureus and a S. epidermidis recipient. These studies describe a means by which methicillin resistance can be environmentally disseminated and a novel mechanism, IS-mediated recombination, for the capture and conjugative transfer of genomic islands. © 2016 John Wiley & Sons Ltd.

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July 7, 2019

Highlights of the 11th International Bordetella Symposium: from basic biology to vaccine development.

Pertussis is a severe respiratory disease caused by infection with the bacterial pathogen Bordetella pertussis The disease affects individuals of all ages but is particularly severe and sometimes fatal in unvaccinated young infants. Other Bordetella species cause diseases in humans, animals, and birds. Scientific, clinical, public health, vaccine company, and regulatory agency experts on these pathogens and diseases gathered in Buenos Aires, Argentina from 5 to 8 April 2016 for the 11th International Bordetella Symposium to discuss recent advances in our understanding of the biology of these organisms, the diseases they cause, and the development of new vaccines and other strategies to prevent these diseases. Highlights of the meeting included pertussis epidemiology in developing nations, genomic analysis of Bordetella biology and evolution, regulation of virulence factor expression, new model systems to study Bordetella biology and disease, effects of different vaccines on immune responses, maternal immunization as a strategy to prevent newborn disease, and novel vaccine development for pertussis. In addition, the group approved the formation of an International Bordetella Society to promote research and information exchange on bordetellae and to organize future meetings. A new Bordetella.org website will also be developed to facilitate these goals. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

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July 7, 2019

Complete genome sequences of the Serratia plymuthica strains 3Rp8 and 3Re4-18, two rhizosphere bacteria with antagonistic activity towards fungal phytopathogens and plant growth promoting abilities.

The Serratia plymuthica strains 3Rp8 and 3Re4-18 are motile, Gram-negative, non-sporulating bacteria. Strain 3Rp8 was isolated from the rhizosphere of Brassica napus L. and strain 3Re4-18 from the endorhiza of Solanum tuberosum L. Studies have shown in vitro activity against the soil-borne fungi Verticillium dahliae Kleb., Rhizoctonia solani Kühn, and Sclerotinia sclerotiorum. Here, we announce and describe the complete genome sequence of S. plymuthica 3Rp8 consisting of a single circular chromosome of 5.5 Mb that encodes 4954 protein-coding and 108 RNA-only encoding genes and of S. plymuthica 3Re4-18 consisting of a single circular chromosome of 5.4 Mb that encodes 4845 protein-coding and 109 RNA-only encoding genes. The whole genome sequences and annotations are available in NCBI under the locus numbers CP012096 and CP012097, respectively. The genome analyses revealed genes putatively responsible for the promising plant growth promoting and biocontrol properties including predicting factors such as secretion systems, iron scavenging siderophores, chitinases, secreted proteases, glucanases and non-ribosomal peptide synthetases, as well as unique genomic islands.

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July 7, 2019

Co-infection and emergence of rifamycin resistance during a recurrent Clostridium difficile infection.

Clostridium difficile (Peptoclostridium difficile) is a common health care associated infection with a disproportionately high incidence in elderly patients. Disease symptoms range from mild diarrhoea through to life threatening pseudomembranous colitis. Around 20% of patients may suffer recurrent disease which often requires re-hospitalisation of patients.C. difficile was isolated from stool samples from a patient with two recurrent C. difficile infections. PCR-ribotyping, whole genome sequencing and phenotypic assays were used to characterise these isolates.Genotypic and phenotypic screening of C. difficile isolates revealed multiple PCR-ribotypes present, and the emergence of rifamycin resistance during the infection cycle.Understanding both the clinical and bacterial factors that contribute to the course of recurrent infection could inform strategies to reduce recurrence. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

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July 7, 2019

Dissection of exopolysaccharide biosynthesis in Kozakia baliensis.

Acetic acid bacteria (AAB) are well known producers of commercially used exopolysaccharides, such as cellulose and levan. Kozakia (K.) baliensis is a relatively new member of AAB, which produces ultra-high molecular weight levan from sucrose. Throughout cultivation of two K. baliensis strains (DSM 14400, NBRC 16680) on sucrose-deficient media, we found that both strains still produce high amounts of mucous, water-soluble substances from mannitol and glycerol as (main) carbon sources. This indicated that both Kozakia strains additionally produce new classes of so far not characterized EPS.By whole genome sequencing of both strains, circularized genomes could be established and typical EPS forming clusters were identified. As expected, complete ORFs coding for levansucrases could be detected in both Kozakia strains. In K. baliensis DSM 14400 plasmid encoded cellulose synthase genes and fragments of truncated levansucrase operons could be assigned in contrast to K. baliensis NBRC 16680. Additionally, both K. baliensis strains harbor identical gum-like clusters, which are related to the well characterized gum cluster coding for xanthan synthesis in Xanthomanas campestris and show highest similarity with gum-like heteropolysaccharide (HePS) clusters from other acetic acid bacteria such as Gluconacetobacter diazotrophicus and Komagataeibacter xylinus. A mutant strain of K. baliensis NBRC 16680 lacking EPS production on sucrose-deficient media exhibited a transposon insertion in front of the gumD gene of its gum-like cluster in contrast to the wildtype strain, which indicated the essential role of gumD and of the associated gum genes for production of these new EPS. The EPS secreted by K. baliensis are composed of glucose, galactose and mannose, respectively, which is in agreement with the predicted sugar monomer composition derived from in silico genome analysis of the respective gum-like clusters.By comparative sugar monomer and genome analysis, the polymeric substances secreted by K. baliensis can be considered as unique HePS. Via genome sequencing of K. baliensis DSM 14400 + NBRC 16680 we got first insights into the biosynthesis of these novel HePS, which is related to xanthan and acetan biosynthesis. Consequently, the present study provides the basis for establishment of K. baliensis strains as novel microbial cell factories for biotechnologically relevant, unique polysaccharides.

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July 7, 2019

Complete genome sequence of Defluviimonas alba cai42(T), a microbial exopolysaccharides producer.

Defluviimonas alba cai42(T), isolated from the oil-production water in Xinjiang Oilfield in China, has a strong ability to produce exopolysaccharides (EPS). We hereby present its complete genome sequence information which consists of a circular chromosome and three plasmids. The strain characteristically contains various genes encoding for enzymes involved in EPS biosynthesis, modification, and export. According to the genomic and physiochemical data, it is predicted that the strain has the potential to be utilized in industrial production of microbial EPS. Copyright © 2016 Elsevier B.V. All rights reserved.

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July 7, 2019

Selvamicin, an atypical antifungal polyene from two alternative genomic contexts.

The bacteria harbored by fungus-growing ants produce a variety of small molecules that help maintain a complex multilateral symbiosis. In a survey of antifungal compounds from these bacteria, we discovered selvamicin, an unusual antifungal polyene macrolide, in bacterial isolates from two neighboring ant nests. Selvamicin resembles the clinically important antifungals nystatin A1 and amphotericin B, but it has several distinctive structural features: a noncationic 6-deoxymannose sugar at the canonical glycosylation site and a second sugar, an unusual 4-O-methyldigitoxose, at the opposite end of selvamicin’s shortened polyene macrolide. It also lacks some of the pharmacokinetic liabilities of the clinical agents and appears to have a different target. Whole genome sequencing revealed the putative type I polyketide gene cluster responsible for selvamicin’s biosynthesis including a subcluster of genes consistent with selvamicin’s 4-O-methyldigitoxose sugar. Although the selvamicin biosynthetic cluster is virtually identical in both bacterial producers, in one it is on the chromosome, in the other it is on a plasmid. These alternative genomic contexts illustrate the biosynthetic gene cluster mobility that underlies the diversity and distribution of chemical defenses by the specialized bacteria in this multilateral symbiosis.

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