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Gram-positive Bacteria (gram-positive + bacteria)
Kinds of Gram-positive Bacteria Selected AbstractsMultiply Resistant Gram-Positive Bacteria: Vancomycin-Resistant Enterococcus in Solid Organ Transplant RecipientsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 2009P. Muñoz First page of article [source] Sortase-Mediated Ligation: A Gift from Gram-Positive Bacteria to Protein EngineeringCHEMBIOCHEM, Issue 5 2009Shinya Tsukiji Dr. Abstract A new enzymatic protein ligation tool, sortase, has recently emerged from Gram-positive bacteria. This article outlines the technique, sortase-mediated ligation, and its applications in protein engineering, which include the introduction of unnatural molecules into proteins, protein immobilization, protein,protein conjugation, protein cyclization, as a self-cleavable tag for protein expression, protein,PNA hybrids, neoglycoconjugates, and cell-surface protein labeling, etc. [source] Cutaneous infections in the elderly: diagnosis and managementDERMATOLOGIC THERAPY, Issue 3 2003Jeffrey M. Weinberg ABSTRACT:, Over the past several years there have been many advances in the diagnosis and treatment of cutaneous infectious diseases. This review focuses on the three major topics of interest in the geriatric population: herpes zoster and postherpetic neuralgia (PHN), onychomycosis, and recent advances in antibacterial therapy. Herpes zoster in adults is caused by reactivation of the varicella-zoster virus (VZV) that causes chickenpox in children. For many years acyclovir was the gold standard of antiviral therapy for the treatment of patients with herpes zoster. Famciclovir and valacyclovir, newer antivirals for herpes zoster, offer less frequent dosing. PHN refers to pain lasting ,2 months after an acute attack of herpes zoster. The pain may be constant or intermittent and may occur spontaneously or be caused by seemingly innocuous stimuli such as a light touch. Treatment of established PHN through pharmacologic and nonpharmacologic therapy will be discussed. In addition, therapeutic strategies to prevent PHN will be reviewed. These include the use of oral corticosteroids, nerve blocks, and treatment with standard antiviral therapy. Onychomycosis, or tinea unguium, is caused by dermatophytes in the majority of cases, but can also be caused by Candida and nondermatophyte molds. Onychomycosis is found more frequently in the elderly and in more males than females. There are four types of onychomycosis: distal subungual onychomycosis, proximal subungual onychomycosis, white superficial onychomycosis, and candidal onychomycosis. Over the past several years, new treatments for this disorder have emerged which offer shorter courses of therapy and greater efficacy than previous therapies. The treatment of bacterial skin and skin structure infections in the elderly is an important issue. There has been an alarming increase in the incidence of gram-positive infections, including resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and drug-resistant pneumococci. While vancomycin has been considered the drug of last defense against gram-positive multidrug-resistant bacteria, the late 1980s saw an increase in vancomycin-resistant bacteria, including vancomycin-resistant enterococci (VRE). More recently, strains of vancomycin-intermediate resistant S. aureus (VISA) have been isolated. Gram-positive bacteria, such as S. aureus and Streptococcus pyogenes are often the cause of skin and skin structure infections, ranging from mild pyodermas to complicated infections including postsurgical wound infections, severe carbunculosis, and erysipelas. With limited treatment options, it has become critical to identify antibiotics with novel mechanisms of activity. Several new drugs have emerged as possible therapeutic alternatives, including linezolid and quinupristin/dalfopristin. [source] Simultaneous determination of metronidazole and spiramycin in bulk powder and in tablets using different spectrophotometric techniquesDRUG TESTING AND ANALYSIS, Issue 1 2010Fatma I. Khattab Abstract Metronidazole (MZ) is an anti-infective drug used in the treatment of anaerobic bacterial and protozoa infections in humans. It is also used as a vetinary antiparasitic drug. Spiramycin (SP) is a medium-spectrum antibiotic with high effectiveness against Gram-positive bacteria. Three simple, sensitive, selective and precise spectrophotometric methods were developed and validated for the simultaneous determination of MZ and SP in their pure form and in pharmaceutical formulations. In methods A and B, MZ was determined by the application of direct spectrophotometry and by measuring its zero-order (D0) absorption spectra at its ,max = 311 nm. In method A, SP was determined by the application of first derivative spectrophotometry (D1) and by measuring the amplitude at 218.3 nm. In method B, the first derivative of the ratio spectra (DD1) was applied, and SP was determined by measuring the peak amplitude at 245.6 nm. Method C entailed mean centring of the ratio spectra (MCR), which allows the determination of both MZ and SP. The methods developed were used for the determination of MZ and SP over a concentration range of 5,25 µg ml,1. The proposed methods were used to determine both drugs in their pure, powdered forms with mean percentage recoveries of 100.16 ± 0.73 for MZ in methods A and B, 101.10 ± 0.90 in method C, 100.09 ± 0.70, 100.02 ± 0.88 and 100.49 ± 1.26 for SP in methods A, B and C, respectively. The proposed methods were proved using laboratory-prepared mixtures of the two drugs and were successfully applied to the analysis of MZ and SP in tablet formulation without any interference from each other or from the excipients. The results obtained by applying the proposed methods were compared statistically with a reported HPLC method and no significant difference was observed between these methods regarding both accuracy and precision. Copyright © 2010 John Wiley & Sons, Ltd. [source] The microbial community of Vetiver root and its involvement into essential oil biogenesisENVIRONMENTAL MICROBIOLOGY, Issue 10 2008Luigi Del Giudice Summary Vetiver is the only grass cultivated worldwide for the root essential oil, which is a mixture of sesquiterpene alcohols and hydrocarbons, used extensively in perfumery and cosmetics. Light and transmission electron microscopy demonstrated the presence of bacteria in the cortical parenchymatous essential oil-producing cells and in the lysigen lacunae in close association with the essential oil. This finding and the evidence that axenic Vetiver produces in vitro only trace amounts of oil with a strikingly different composition compared with the oils from in vivo Vetiver plants stimulated the hypothesis of an involvement of these bacteria in the oil metabolism. We used culture-based and culture-independent approaches to analyse the microbial community of the Vetiver root. Results demonstrate a broad phylogenetic spectrum of bacteria, including ,-, ,- and ,- Proteobacteria, high-G+C-content Gram-positive bacteria, and microbes belonging to the Fibrobacteres/Acidobacteria group. We isolated root-associated bacteria and showed that most of them are able to grow by using oil sesquiterpenes as a carbon source and to metabolize them releasing into the medium a large number of compounds typically found in commercial Vetiver oils. Several bacteria were also able to induce gene expression of a Vetiver sesquiterpene synthase. These results support the intriguing hypothesis that bacteria may have a role in essential oil biosynthesis opening the possibility to use them to manoeuvre the Vetiver oil molecular structure. [source] d -Alanyl ester depletion of teichoic acids in Lactobacillus reuteri 100-23 results in impaired colonization of the mouse gastrointestinal tractENVIRONMENTAL MICROBIOLOGY, Issue 7 2007Jens Walter Summary The dlt operon of Gram-positive bacteria encodes proteins required for the incorporation of d -alanine esters into cell wall-associated teichoic acids (TA). d -Alanylation of TA has been shown to be important for acid tolerance, resistance to antimicrobial peptides, adhesion, biofilm formation, and virulence of a variety of pathogenic organisms. The aim of this study was to determine the importance of d -alanylation for colonization of the gastrointestinal tract by Lactobacillus reuteri 100-23. Insertional inactivation of the dltA gene resulted in complete depletion of d -alanine substitution of lipoteichoic acids. The dlt mutant had similar growth characteristics as the wild type under standard in vitro conditions, but formed lower population sizes in the gastrointestinal tract of ex- Lactobacillus -free mice, and was almost eliminated from the habitat in competition experiments with the parental strain. In contrast to the wild type, the dlt mutant was unable to form a biofilm on the forestomach epithelium during gut colonization. Transmission electron microscope observations showed evidence of cell wall damage of mutant bacteria present in the forestomach. The dlt mutant had impaired growth under acidic culture conditions and increased susceptibility to the cationic peptide nisin relative to the wild type. Ex vivo adherence of the dlt mutant to the forestomach epithelium was not impaired. This study showed that d -alanylation is an important cell function of L. reuteri that seems to protect this commensal organism against the hostile conditions prevailing in the murine forestomach. [source] Microbial community structure of ethanol type fermentation in bio-hydrogen productionENVIRONMENTAL MICROBIOLOGY, Issue 5 2007Nanqi Ren Summary Three continuous stirred-tank reactors (CSTRs) were used for H2 production from molasses wastewater at influent pH of 6.0,6.5 (reactor A), 5.5,6.0 (reactor B), or 4.0,4.5 (reactor C). After operation for 28 days, the microbial community formed ethanol type (C), propionate type (A) and ethanol-butyrate-mixed type (B) fermentation. The H2 production rate was the highest for ethanol type fermentation, 0.40 l (g VSS),1 day,1 or 0.45 l H2 (g COD removed),1. Microbial community dynamics and diversity were analysed using double-gradient denaturing gradient gel electrophoresis (DG-DGGE). Denaturing gradient gel electrophoresis profiles indicated that the community structures changed quickly in the first 14 days. Phylogenetic analysis indicated that the dominant bacterial groups were low G+C Gram-positive bacteria, Bacteroides, ,-Proteobacteria and Actinobacteria; ,-Proteobacteria, ,-Proteobacteria, ,-Proteobacteria and Spirochaetes were also presented as minor groups in the three reactors. H2 -producing bacteria were affiliated with Ethanoligenens, Acetanaerobacterium, Clostridium, Megasphaera, Citrobacter and Bacteroides. An ethanol-based H2 -producing bacterium, Ethanoligenens harbinense CGMCC1152, was isolated from reactor C and visualized using fluorescence in situ hybridization (FISH) to be 19% of the eubacteria in reactor C. In addition, isoenzyme activity staining for alcohol dehydrogenase (ADH) supported that the majority of ethanol-producing bacteria were affiliated with Ethanoligenens in the microbial community. [source] Novel microbial diversity adherent to plant biomass in the herbivore gastrointestinal tract, as revealed by ribosomal intergenic spacer analysis and rrs gene sequencingENVIRONMENTAL MICROBIOLOGY, Issue 4 2005Ross Larue Summary It is well recognized that a dynamic biofilm develops upon plant biomass in the herbivore gastrointestinal tract, but this component of the microbiome has not previously been specifically sampled, or directly compared with the biodiversity present in the planktonic fraction of digesta. In this study, the digesta collected from four sheep fed two different diets was separated into three fractions: the planktonic phase, and the microbial populations either weakly or tightly adherent to plant biomass. The community DNA prepared from each fraction was then subjected to both ribosomal intergenic spacer analysis (RISA) and denaturing gradient gel electrophoresis (DGGE). Both types of analysis showed that dietary factors influence community structure, and that the adherent fractions produced more complex profiles. The RIS-clone libraries prepared from the planktonic and adherent populations were then subjected to restriction fragment length polymorphism (RFLP) and DNA sequence analyses, which resulted in a far greater degree of discrimination among the fractions. Although many of the sequenced clones from the adherent populations were assigned to various clusters within the low G+C Gram-positive bacteria, the clone libraries from animals consuming an all-grass diet were largely comprised of novel lineages of Clostridium, while in animals consuming the starch-containing diet, Selenomonas and Ruminococcus spp. were the dominant low G+C Gram-positive bacteria. Additionally, the libraries from hay-fed animals also contained clones most similar to asaccharolytic Clostridia, and other Gram-positive bacteria that specialize in the transformation of plant phenolic compounds and the formation of cinnamic, phenylacetic and phenylpropionic acids. These results reveal, for the first time, the phylogeny of adherent subpopulations that specialize in the transformation of plant lignins and other secondary compounds, which potentiate polysaccharide hydrolysis by other members of the biofilm. [source] Proteolytic activation and function of the cytokine Spätzle in the innate immune response of a lepidopteran insect, Manduca sextaFEBS JOURNAL, Issue 1 2010Chunju An The innate immune response of insects includes induced expression of genes encoding a variety of antimicrobial peptides. The signaling pathways that stimulate this gene expression have been well characterized by genetic analysis in Drosophila melanogaster, but are not well understood in most other insect species. One such pathway involves proteolytic activation of a cytokine called Spätzle, which functions in dorsal,ventral patterning in early embryonic development and in the antimicrobial immune response in larvae and adults. We have investigated the function of Spätzle in a lepidopteran insect, Manduca sexta, in which hemolymph proteinases activated during immune responses have been characterized biochemically. Two cDNA isoforms for M. sexta Spätzle-1 differ because of alternative splicing, resulting in a 10 amino acid residue insertion in the pro-region of proSpätzle-1B that is not present in proSpätzle-1A. The proSpätzle-1A cDNA encodes a 32.7 kDa polypeptide that is 23% and 44% identical to D. melanogaster and Bombyx mori Spätzle-1, respectively. Recombinant proSpätzle-1A was a disulfide-linked homodimer. M. sexta hemolymph proteinase 8 cleaved proSpätzle-1A to release Spätzle-C108, a dimer of the C-terminal 108 residue cystine-knot domain. Injection of Spätzle-C108, but not proSpätzle-1A, into larvae stimulated expression of several antimicrobial peptides and proteins, including attacin-1, cecropin-6, moricin, lysozyme, and the immunoglobulin domain protein hemolin, but did not significantly affect the expression of two bacteria-inducible pattern recognition proteins, immulectin-2 and ,-1,3-glucan recognition protein-2. The results of this and other recent studies support a model for a pathway in which the clip-domain proteinase pro-hemolymph proteinase 6 becomes activated in plasma upon exposure to Gram-negative or Gram-positive bacteria or to ,-1,3-glucan. Hemolymph proteinase 6 then activates pro-hemolymph proteinase 8, which in turn activates Spätzle-1. The resulting Spätzle-C108 dimer is likely to function as a ligand to activate a Toll pathway in M. sexta as a response to a wide variety of microbial challenges, stimulating a broad response to infection. Structured digital abstract ,,MINT-7295125: Spätzle 1A (uniprotkb:C8BMD1) and Spätzle 1A (uniprotkb:C8BMD1) bind (MI:0407) by comigration in gel electrophoresis (MI:0807) [source] The surface-associated elongation factor Tu is concealed for antibody binding on viable pneumococci and meningococciFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2008Jan Kolberg Abstract Proteome analyses revealed that elongation factor-Tu (EF-Tu) is associated with cytoplasmic membranes of Gram-positive bacteria and outer membranes of Gram-negative bacteria. It is still debatable whether EF-Tu is located on the external side or the internal side of the membranes. Here, we have generated two new monoclonal antibodies (mAbs) and polyclonal rabbit antibodies against pneumococcal EF-Tu. These antibodies were used to investigate the amount of surface-exposed EF-Tu on viable bacteria using a flow cytometric analysis. The control antibodies recognizing the pneumococcal surface protein A and phosphorylcholine showed a significant binding to viable pneumococci. In contrast, anti-EF-Tu antibodies did not recognize pneumococcal EF-Tu. However, heat killing of pneumococci lacking capsular polysaccharides resulted in specific antibody binding to EF-Tu and, moreover, increased the exposure of recognized phosphorylcholine epitopes. Similarly, our EF-Tu-specific antibodies did not recognize EF-Tu of viable Neisseria meningitidis. However, pretreatment of meningococci with ethanol resulted in specific antibody binding to EF-Tu on outer membranes. Importantly, these treatments did not destroy the membrane integrity as analysed with control mAbs directed against cytoplasmic proteins. In conclusion, our flow cytrometric assays emphasize the importance of using viable bacteria and not heat-killed or ethanol-treated bacteria for surface-localization experiments of proteins, because these treatments modulate the cytoplasmic and outer membranes of bacteria and the binding results may not reflect the situation under physiological conditions. [source] Intramembrane-sensing histidine kinases: a new family of cell envelope stress sensors in Firmicutes bacteriaFEMS MICROBIOLOGY LETTERS, Issue 2 2006Thorsten Mascher Abstract Two-component signal-transducing systems (TCS) consist of a histidine kinase (HK) that senses a specific environmental stimulus, and a cognate response regulator (RR) that mediates the cellular response. Most HK are membrane-anchored proteins harboring two domains: An extracytoplasmic input and a cytoplasmic transmitter (or kinase) domain, separated by transmembrane helices that are crucial for the intramolecular information flow. In contrast to the cytoplasmic domain, the input domain is highly variable, reflecting the plethora of different signals sensed. Intramembrane-sensing HK (IM-HK) are characterized by their short input domain, consisting solely of two putative transmembane helices. They lack an extracytoplasmic domain, indicative for a sensing process at or from within the membrane interface. Most proteins sharing this domain architecture are found in Firmicutes bacteria. Two major groups can be differentiated based on sequence similarity and genomic context: (1) BceS-like IM-HK that are functionally and genetically linked to ABC transporters, and (2) LiaS-like IM-HK, as part of three-component systems. Most IM-HK sense cell envelope stress, and identified target genes are often involved in maintaining cell envelope integrity, mediating antibiotic resistance, or detoxification processes. Therefore, IM-HK seem to constitute an important mechanism of cell envelope stress response in low G+C Gram-positive bacteria. [source] Phylogenetic and structural analyses of the oxa1 family of protein translocasesFEMS MICROBIOLOGY LETTERS, Issue 2 2001Ming-Ren Yen Abstract Mitochondrial Oxa1p homologs have been shown to function in protein export and membrane insertion in bacteria, mitochondria and chloroplasts, but their mode of action, organismal distribution and evolutionary origins are poorly understood. All sequenced homologs of Oxa1p were retrieved from the databases and multiply aligned. All organisms with a fully sequenced genome possess at least one Oxa1p homolog showing that the family is truly ubiquitous. Most prokaryotes possess just one Oxa1p homolog, but several Gram-positive bacteria and one archaeon possess two, and eukaryotes may have as many as six. Although these proteins vary in length over a 5-fold range, they exhibit a common hydrophobic core region of about 200 residues. Multiple sequence alignments reveal conserved residues and provide the basis for structural and phylogenetic analyses that serve to characterize the Oxa1 family. [source] Evolution of peptidoglycan biosynthesis under the selective pressure of antibiotics in Gram-positive bacteriaFEMS MICROBIOLOGY REVIEWS, Issue 2 2008Jean-Luc Mainardi Abstract Acquisition of resistance to the two classes of antibiotics therapeutically used against Gram-positive bacteria, the glycopeptides and the ,-lactams, has revealed an unexpected flexibility in the peptidoglycan assembly pathway. Glycopeptides select for diversification of the fifth position of stem pentapeptides because replacement of d -Ala by d -lactate or d -Ser at this position prevents binding of the drugs to peptidoglycan precursors. The substitution is generally well tolerated by the classical d,d -transpeptidases belonging to the penicillin-binding protein family, except by low-affinity enzymes. Total elimination of the fifth residue by a d,d -carboxypeptidase requires a novel cross-linking enzyme able to process the resulting tetrapeptide stems. This enzyme, an l,d -transpeptidase, confers cross-resistance to ,-lactams and glycopeptides. Diversification of the side chain of the precursors, presumably in response to the selective pressure of peptidoglycan endopeptidases, is controlled by aminoacyl transferases of the Fem family that redirect specific aminoacyl-tRNAs from translation to peptidoglycan synthesis. Diversification of the side chains has been accompanied by a parallel divergent evolution of the substrate specificity of the l,d -transpeptidases, in contrast to the d,d -transpeptidases, which display an unexpected broad specificity. This review focuses on the role of antibiotics in selecting or counter-selecting diversification of the structure of peptidoglycan precursors and their mode of polymerization. [source] Genetic features of circular bacteriocins produced by Gram-positive bacteriaFEMS MICROBIOLOGY REVIEWS, Issue 1 2008Mercedes Maqueda Abstract This review highlights the main genetic features of circular bacteriocins, which require the co-ordinated expression of several genetic determinants. In general terms, it has been demonstrated that the expression of such structural genes must be combined with the activity of proteins involved in maturation (cleavage/circularization) and secretion outside the cell via different transporter systems, as well as multifaceted immunity mechanisms essential to ensuring the bacteria's self-protection against such strong inhibitors. Several circular antibacterial peptides produced by Gram-positive bacteria have been described to date, including enterocin AS-48, from Enterococcus faecalis S-48 (the first one characterized), gassericin A, from Lactobacillus gasseri LA39, and a similar one, reutericin 6, from Lactobacillus reuteri LA6, butyrivibriocin AR10, from the ruminal anaerobe Butyrivibrio fibrisolvens AR10, uberolysin, from Streptococcus uberis, circularin A, from Clostridium beijerinckii ATCC 25752, and subtilosin A, from Bacillus subtilis. We summarize here the progress made in the understanding of their principal genetic features over the last few years, during which the functional roles of circular proteins with wide biological activity have become clearer. [source] The biology of lantibiotics from the lacticin 481 group is coming of ageFEMS MICROBIOLOGY REVIEWS, Issue 2 2007Alain Dufour Abstract Lantibiotics are antimicrobial peptides from the bacteriocin family, secreted by Gram-positive bacteria. These peptides differ from other bacteriocins by the presence of (methyl)lanthionine residues, which result from enzymatic modification of precursor peptides encoded by structural genes. Several groups of lantibiotics have been distinguished, the largest of which is the lacticin 481 group. This group consists of at least 16 members, including lacticin 481, streptococcin A-FF22, mutacin II, nukacin ISK-1, and salivaricins. We present the first review devoted to this lantibiotic group, knowledge of which has increased significantly within the last few years. After updating the group composition and defining the common properties of these lantibiotics, we highlight the most recent developments. The latter concern: transcriptional regulation of the lantibiotic genes; understanding the biosynthetic machinery, in particular the ability to perform in vitro prepeptide maturation; characterization of a novel type of immunity protein; and broad application possibilities. This group differs in many aspects from the best known lantibiotic group (nisin group), but shares properties with less-studied groups such as the mersacidin, cytolysin and lactocin S groups. [source] Listeriolysin O: a key protein of Listeria monocytogenes with multiple functionsFEMS MICROBIOLOGY REVIEWS, Issue 4 2006Samer Kayal Abstract Cholesterol-dependent cytolysins (CDCs) are produced by a large number of pathogenic Gram-positive bacteria. Most of these single-chain proteins are secreted in the extracellular medium. Among the species producing CDCs, only two species belonging to the genus Listeria (Listeria monocytogenes and Listeria ivanovii) are able to multiply intracellularly and release their toxins in the phagosomal compartment of the infected host cell. This review provides an updated overview on the importance of listeriolysin O (LLO) in the pathogenicity of L. monocytogenes, focusing mainly on two aspects: (1) the structure,function relationship of LLO and (2) its role in intra- and extracellular signalling. We first examine the specific sequence determinants, or protein domains, that make this cytolysin so well adapted to the intracellular lifestyle of L. monocytogenes. The roles that LLO has in cellular signalling events in the context of relations to pathogenesis are also discussed. [source] Lipopolysaccharides of anaerobic beer spoilage bacteria of the genus Pectinatus, lipopolysaccharides of a Gram-positive genusFEMS MICROBIOLOGY REVIEWS, Issue 5 2004Ilkka M. Helander Abstract Bacteria of the genus Pectinatus emerged during the seventies as contaminants and spoilage organisms in packaged beer. This genus comprises two species, Pectinatus cerevisiiphilus and Pectinatus frisingensis; both are strict anaerobes. On the basis of genomic properties the genus is placed among low GC Gram-positive bacteria (phylum Firmicutes, class Clostridia, order Clostridiales, family Acidaminococcaceae). Despite this assignment, Pectinatus bacteria possess an outer membrane and lipopolysaccharide (LPS) typical of Gram-negative bacteria. The present review compiles the structural and compositional studies performed on Pectinatus LPS. These lipopolysaccharides exhibit extensive heterogeneity, i.e. several macromolecularly and structurally distinct LPS molecules are produced by each strain. Whereas heterogeneity is a common property in lipopolysaccharides, Pectinatus LPS have been shown to contain exceptional carbohydrate structures, consisting of a fairly conserved core region that carries a large non-repetitive saccharide that probably replaces the O-specific chain. Such structures represent a novel architectural principle of the LPS molecule. [source] Cell wall teichoic acids: structural diversity, species specificity in the genus Nocardiopsis, and chemotaxonomic perspectiveFEMS MICROBIOLOGY REVIEWS, Issue 3 2001Irina B Naumova Abstract Data on the structures of cell wall teichoic acids, the anionic carbohydrate-containing polymers, found in many Gram-positive bacteria have been summarized and the polymers of the actinomycete genus Nocardiopsis have been considered from the taxonomic standpoint. The structures of these polymers or their combinations have been demonstrated to be indicative of each of seven Nocardiopsis species and two subspecies, verified by the DNA,DNA relatedness data, and to correlate well with the grouping of the organisms based on 16S rDNA sequences. As each of the intrageneric taxa discussed is definable by the composition of teichoic acids, the polymers are considered to be valuable taxonomic markers for the Nocardiopsis species and subspecies. The 13C NMR spectra of the polymers, data on the products of their chemical degradation, and distinguishing constituents of whole cell walls derived from teichoic acids are discussed, which are useful for identification of certain polymers and members of the genus Nocardiopsis at the species and subspecies level in microbiological practice. [source] Chemical constituents and antimicrobial activities of the essential oil of Acroptilon repens (L.) DCFLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2006Hassan Norouzi-Arasi Abstract The volatile oil from the aerial parts of Acroptilon repens (L.) DC. (Russian knapweed) growing wild in Iran was investigated by GC and GC,MS. Twenty-two components, representing 84.0% of the oil, were identified. The main constituents of the oil were caryophyllene oxide (36.6%), , -copaene (15.6%), , -caryophylene (10.0%) and , -copaene-4- , -ol (5.0%). In addition, the oil was assayed against six Gram-positive and Gram-negative bacteria by measuring the growth inhibitory zone. The oil of A. repens inhibited the growth of Gram-positive bacteria. Staphylococcus saprophyticus and Staphylococcus epidermidis showed strong inhibition zones, while Staphylococcus aureus showed a lower inhibition. The Gram-negative bacteria were insensitive to the oil. Copyright © 2005 John Wiley & Sons, Ltd. [source] Chemical composition and biological activities of the essential oils of Salvia canariensisFLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2006M. C. García Vallejo Abstract Comparative studies of the chemical composition of steam-distilled essential oils from cultivated Salvia canariensis, collected at different seasons of the year, were studied. The essential oils were analysed by gas chomatography,mass spectrometry: the major components were bornyl acetate (17.8,28.6%), , -caryophyllene (12.7,30.2%), , -pinene (4.6,9.5%) and viridiflorol (13.9,17.3%) in all samples. The essential oils were evaluated for antimicrobial and cytostatic activities and enzymatic inhibitions of xanthine oxidase, , -glucosidase and , -glucuronidase. Concerning the antimicrobial and cytotoxic tests, the oils showed interesting activities towards different Gram-positive bacteria (MIC 45,35 µg[sol ]ml), but had no effect against eukaryotic cells. Copyright © 2005 John Wiley & Sons, Ltd. [source] When fathers make the difference: efficacy of male sexually selected antimicrobial glands in enhancing fish hatching successFUNCTIONAL ECOLOGY, Issue 1 2010Matteo Pizzolon Summary 1.,Egg and offspring resistance to pathogens is a major determinant of survival and has been mainly ascribed to maternal factors. However, paternal production of antimicrobials was recently suggested to increase offspring survival in species where males perform egg care. 2.,In the peacock blenny, Salaria pavo, a demersal spawning species where males exhibit a pair of anal glands producing lysozyme-like compounds, we tested the antimicrobial activity and the egg protection efficacy of these glands. The anal gland secretion (AGS) has an inhibitory effect on the growth of both Gram-negative and Gram-positive bacteria, including those causing the most severe fish diseases in marine culture. The egg clutches cared for by males deprived of anal glands have a significantly lower survival rate than those cared for by sham-operated males and non-viable eggs showed clear signs of bacterial infection. 3.,Anal gland secretion production and its protein content are proportional to gland size. In species where male parental care plays a crucial role in offspring survival, females are expected to assess mates selecting those traits that are reliably associated with parental ability. Hence, we experimentally challenged females with dummy males differing in anal gland size. Females definitely preferred dummy males with larger anal glands, suggesting that their choice is driven by the pursuit of direct fecundity benefits. 4.,These findings indicate that antimicrobial production is a crucial component of male parental care. The contribution of antimicrobials to male performance as fathers suggests that the development of traits devoted to this function may influence male attractiveness and be sexually selected. [source] The impact of metabolic state on Cd adsorption onto bacterial cellsGEOBIOLOGY, Issue 3 2007K. J. JOHNSON ABSTRACT This study examines the effect of bacterial metabolism on the adsorption of Cd onto Gram-positive and Gram-negative bacterial cells. Metabolically active Gram-positive cells adsorbed significantly less Cd than non-metabolizing cells. Gram-negative cells, however, showed no systematic difference in Cd adsorption between metabolizing and non-metabolizing cells. The effect of metabolism on Cd adsorption to Gram-positive cells was likely due to an influx of protons in and around the cell wall from the metabolic proton motive force, promoting competition between Cd and protons for adsorption sites on the cell wall. The relative lack of a metabolic effect on Cd adsorption onto Gram-negative compared to Gram-positive cells suggests that Cd binding in Gram-negative cells is focused in a region of the cell wall that is not reached, or is unaffected by this proton flux. Thermodynamic modeling was used to estimate that proton pumping causes the pH in the cell wall of metabolizing Gram-positive bacteria to decrease from the bulk solution value of 7.0 to approximately 5.7. [source] Geobiological analysis using whole genome-based tree building applied to the Bacteria, Archaea, and EukaryaGEOBIOLOGY, Issue 1 2003Christopher H. House ABSTRACT We constructed genomic trees based on the presence and absence of families of protein-encoding genes observed in 55 prokaryotic and five eukaryotic genomes. There are features of the genomic trees that are not congruent with typical rRNA phylogenetic trees. In the bacteria, for example, Deinococcus radiodurans associates with the Gram-positive bacteria, a result that is also seen in some other phylogenetic studies using whole genome data. In the Archaea, the methanogens plus Archaeoglobus form a united clade and the Euryarchaeota are divided with the two Thermoplasma genomes and Halobacterium sp. falling below the Crenarchaeota. While the former appears to be an accurate representation of methanogen-relatedness, the misplacement of Halobacterium may be an artefact of parsimony. These results imply the last common ancestor of the Archaea was not a methanogen, leaving sulphur reduction as the most geochemically plausible metabolism for the base of the archaeal crown group. It also suggests that methanogens were not a component of the Earth's earliest biosphere and that their origin occurred sometime during the Archean. In the Eukarya, the parsimony analysis of five Eukaryotes using the Crenarchaeota as an outgroup seems to counter the Ecdysozoa hypothesis, placing Caenorhabditis elegans (Nematoda) below the common ancestor of Drosophila melanogaster (Arthropoda) and Homo sapiens (Chordata) even when efforts are made to counter the possible effects of a faster rate of sequence evolution for the C. elegans genome. Further analysis, however, suggests that the gene loss of ,animal' genes is highest in C. elegans and is obscuring the relationships of these organisms. [source] Identification and characterization of antimicrobial peptide, defensin, in the taiga tick, Ixodes persulcatusINSECT MOLECULAR BIOLOGY, Issue 4 2009Y. Saito Abstract Ixodes persulcatus is the primary vector for human tick-borne diseases in Japan. A cDNA library was constructed from whole body homogenates of fed nymphs of I. persulcatus. From this library, one cDNA encoding defensin-like antimicrobial peptide was identified. The amino-acid sequence showed high similarity to those of the defensins of other ticks and arthropods. I. persulcatus defensin mRNA transcripts were detected at all life cycle stages of fed ticks and found to be predominantly expressed in the midguts of adult female ticks, but not in the salivary glands, a finding corroborated by Western blotting analysis. To investigate the function of I. persulcatus defensin, we examined its antibacterial activity by evaluation of growth of several bacterial strains in the presence of the synthetic peptide. The defensin from I. persulcatus markedly inhibited the growth of Gram-positive bacteria including Staphylococcus aureus, Bacillus subtilis and Corynebacterium renale, but not Gram-negative bacteria except Escherichia coli O157. In conclusion, these results suggest that I. persulcatus defensin may be playing a significant role in the defence against microbes from bloodmeals. [source] Isolation and partial characterization of a bacteriocin produced by Pediococcus pentosaceus K23-2 isolated from KimchiJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2008M.S. Shin Abstract Aims:, Screening and partial characterization of a bacteriocin produced by Pediococcus pentosaceus K23-2 isolated from Kimchi, a traditional Korean fermented vegetable. Methods and Results:, A total of 1000 lactic acid bacteria were isolated from various Kimchi samples and screened for the production of bacteriocin. Pediocin K23-2, a bacteriocin produced by the Pediococcus pentosaceus K23-2 strain, showed strong inhibitory activity against Listeria monocytogenes. The bacteriocin activity remained unchanged after 15 min of heat treatment at 121°C or exposure to organic solvents; however, it diminished after treatment with proteolytic enzymes. The bacteriocin was maximally produced at 37°C, when the pH of the culture broth was maintained at 5·0 during the fermentation, although the optimum pH for growth was 7·0. The molecular weight of the bacteriocin was about 5 kDa according to a tricine SDS-PAGE analysis. Conclusions:,Pediococcus pentosaceus K23-2 isolated from Kimchi produces a bacteriocin, which shares similar characteristics to the Class IIa bacteriocins. The bacteriocin is heat stable and shows wide antimicrobial activity against Gram-positive bacteria, especially L. monocytogenes. Significance and Impact of the Study:, Pediocin K23-2 and pediocin K23-2-producing P. pentosaceus K23-2 could potentially be used in the food and feed industries as natural biopreservatives, and for probiotic application to humans or livestock. [source] Identification of Bacillus spp. from Bikalga, fermented seeds of Hibiscus sabdariffa: phenotypic and genotypic characterizationJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2008L.I.I. Ouoba Abstract Aims:, To identify Bacillus spp. responsible of the fermentation of Hibiscus sabdariffa for production of Bikalga, an alkaline fermented food used as a condiment in Burkina Faso. Methods and Results:, Seventy bacteria were isolated from Bikalga produced in different regions of Burkina Faso and identified by phenotyping and genotyping using PCR amplification of the 16S-23S rDNA intergenic transcribed spacer (ITS-PCR), repetitive sequence-based PCR (rep-PCR) and DNA sequencing. The isolates were characterized as motile, rod-shaped, endospore forming, catalase positive, Gram-positive bacteria. ITS-PCR allowed typing mainly at species level. Rep-PCR was more discriminative and allowed a typing at ssp. level. The DNA sequencing combined with the Blast search program and fermentation profiles using API 50CHB system allowed an identification of the bacteria as Bacillus subtilis, B. licheniformis, B. cereus, B. pumilus, B. badius, Brevibacillus bortelensis, B. sphaericus and B. fusiformis. B. subtilis were the predominant bacterium (42) followed by B. licheniformis (16). Conclusions:, Various species and ssp. of Bacillus are involved in fermentation of H. sabdariffa for production of Bikalga. Significance and Impact of the study:, Selection of starter cultures of Bacillus for controlled production of Bikalga, selection of probiotic bacteria. [source] Commensal bacilli inhibitory to mastitis pathogens isolated from the udder microbiota of healthy cowsJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2006M. Al-Qumber Abstract Aims:, To isolate from the microbiota of the healthy cow udder commensal bacteria having antimicrobial activity against bovine mastitis pathogens, with a long-term view to their potential application as antimastitis probiotics. Methods and Results:, Bacterial isolates from four healthy cow udders were tested for inhibitory activity against three Gram-positive indicator bacteria. This led to the selection of nine broadly inhibitory strains. All were of the Bacillus genus and their antimicrobial activities, which appeared heterogeneous on the basis of their antibacterial spectra and heat susceptibilities, enabled grouping of the inhibitory bacilli into six different inhibitory profiles. All displayed strong in vitro activity against Gram-positive mastitis pathogens. Inhibitory bacilli were recovered from each of the 11 udder samples collected over 7 months from one of these cows and the isolates included representatives of all six inhibitory profiles. Conclusions:, Bacilli present in the udder microbiota of healthy cows can produce a variety of broadly active inhibitors of Gram-positive bacteria, including potential mastitis pathogens. Significance and Impact of the Study:, Inhibitor-producing strains of commensal Bacillus species have been identified, which may have the potential for use as possible antimastitis probiotics. [source] Occurrence of sublethal injury after pulsed electric fields depending on the micro-organism, the treatment medium ph and the intensity of the treatment investigatedJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2005D. García Abstract Aims:, The objective was to investigate the occurrence of sublethal injury after pulsed electric field (PEF) depending on the treatment time, the electric field strength and the pH of the treatment media in two Gram-positive (Bacillus subtilis ssp. niger, Listeria monocytogenes) and six Gram-negative (Escherichia coli, Escherichia coli O157:H7, Pseudomonas aeruginosa, Salmonella serotype Senftenberg 775W, Salmonella serotype Typhimurium, Yersinia enterocolitica) bacterial strains. Methods and Results:, A characteristic behaviour was observed for the Gram-positive and Gram-negative bacteria studied. Whereas Gram-positive bacteria showed a higher PEF resistance at pH 7·0, the Gram-negative were more resistant at pH 4·0. In these conditions, in which bacteria showed their maximum resistance, a large proportion of sublethally injured cells were detected. In most cases, the longer the treatment time and the higher the electric field applied, the greater the proportion of sublethally injured cells that were detected. No sublethal injury was detected when Gram-positive bacteria were treated at pH 4·0 and Gram-negative at pH 7·0. Conclusions:, Sublethal injury was detected after PEF so, bacterial inactivation by PEF is not an ,all or nothing' event. Significance and Impact of the Study:, This work could be useful for improving food preservation by PEF. [source] Detection and characterization of the novel bacteriocin entomocin 9, and safety evaluation of its producer, Bacillus thuringiensis ssp. entomocidus HD9JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2003A. Cherif Abstract Aims: To identify and characterize new bacteriocins from a collection of 41 strains belonging to 27 subspecies of Bacillus thuringiensis, and to evaluate the safety of the producers. Methods and Results:Bacillus thuringiensis ssp. entomocidus HD9 produced in the culture supernatant an antimicrobial activity against Gram-positive bacteria including Listeria monocytogenes, one of four pathogenic Pseudomonas aeruginosa and several fungi. Production of the antibacterial activity, named entomocin 9, started during mid-logarithmic growth reaching its maximum at the early stationary phase. Entomocin 9 retained more than 72% of activity after incubation for 20 min at 121°C. Activity was lost after proteinase K treatment, it was stable in a pH range between 3 and 9, and resistant to lyophilization. After partial purification with ammonium sulphate precipitation followed by gel-filtration and anion-exchange chromatography, an active protein of ca 12·4 kDa was isolated. The mode of action of entomocin 9 was bactericidal and caused cell lysis of growing cells. Despite the presence of a range of virulence related genes, including haemolysin BL, nonhaemolytic enterotoxin, cytotoxin K and several hydrolytic activities, B. thuringiensis HD9 was not toxic against Vero cells. Conclusions: Entomocin 9 is a novel heat-stable, bacteriocin produced by B. thuringiensis HD9. The absence of toxicity against Vero cells suggests the suitability of strain HD9 for a safe application in antimicrobial treatments. Significance and Impact of the Study: New finding on entomocin 9 would make B. thuringiensis attractive in biotechnological applications as an antimicrobial agent in agriculture and food industry. [source] Characterization and mechanism of action of cerein 7, a bacteriocin produced by Bacillus cereus Bc7JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2000J.C. Oscáriz Cerein 7 is a peptidic antibiotic produced by Bacillus cereus Bc7 (CECT 5148) at the end of exponential growth but before sporulation onset. Cerein 7 has a broad spectrum of antibacterial activity against Gram-positive bacteria, but it is inactive against Gram-negative bacteria. The sequence of its amino-terminal end and its characteristics of hydrophobicity and molecular mass make cerein 7 unique among the bacteriocins produced by the soil bacterium B. cereus. In this paper a further characterization of cerein 7 is presented, it is shown that it can be classified as a Klaenhammer's class II bacteriocin and that its mode of action corresponds to that of a membrane-active compound. [source] | ||||||||||||||||||||||||||||||||||