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1

Antimicrobial Resistance in Gram-Positive Bacteria  

Microsoft Academic Search

Gram-positive bacteria are common causes of bloodstream and other infections in hospitalized patients in the United States, and the percentage of nosocomial bloodstream infections caused by antibiotic-resistant gram-positive bacteria is increasing. Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are of particular concern. In the United States, approximately 60% of staphylococcal infections in the intensive care unit are now caused

Louis B. Rice

2006-01-01

2

Bacteriocins of gram-positive bacteria.  

PubMed Central

In recent years, a group of antibacterial proteins produced by gram-positive bacteria have attracted great interest in their potential use as food preservatives and as antibacterial agents to combat certain infections due to gram-positive pathogenic bacteria. They are ribosomally synthesized peptides of 30 to less than 60 amino acids, with a narrow to wide antibacterial spectrum against gram-positive bacteria; the antibacterial property is heat stable, and a producer strain displays a degree of specific self-protection against its own antibacterial peptide. In many respects, these proteins are quite different from the colicins and other bacteriocins produced by gram-negative bacteria, yet customarily they also are grouped as bacteriocins. Although a large number of these bacteriocins (or bacteriocin-like inhibitory substances) have been reported, only a few have been studied in detail for their mode of action, amino acid sequence, genetic characteristics, and biosynthesis mechanisms. Nevertheless, in general, they appear to be translated as inactive prepeptides containing an N-terminal leader sequence and a C-terminal propeptide component. During posttranslational modifications, the leader peptide is removed. In addition, depending on the particular type, some amino acids in the propeptide components may undergo either dehydration and thioether ring formation to produce lanthionine and beta-methyl lanthionine (as in lantibiotics) or thio ester ring formation to form cystine (as in thiolbiotics). Some of these steps, as well as the translocation of the molecules through the cytoplasmic membrane and producer self-protection against the homologous bacteriocin, are mediated through specific proteins (enzymes). Limited genetic studies have shown that the structural gene for such a bacteriocin and the genes encoding proteins associated with immunity, translocation, and processing are present in a cluster in either a plasmid, the chromosome, or a transposon. Following posttranslational modification and depending on the pH, the molecules may either be released into the environment or remain bound to the cell wall. The antibacterial action against a sensitive cell of a gram-positive strain is produced principally by destabilization of membrane functions. Under certain conditions, gram-negative bacterial cells can also be sensitive to some of these molecules. By application of site-specific mutagenesis, bacteriocin variants which may differ in their antimicrobial spectrum and physicochemical characteristics can be produced. Research activity in this field has grown remarkably but sometimes with an undisciplined regard for conformity in the definition, naming, and categorization of these molecules and their genetic effectors. Some suggestions for improved standardization of nomenclature are offered.

Jack, R W; Tagg, J R; Ray, B

1995-01-01

3

Conjugative Plasmid Transfer in Gram-Positive Bacteria  

PubMed Central

Conjugative transfer of bacterial plasmids is the most efficient way of horizontal gene spread, and it is therefore considered one of the major reasons for the increase in the number of bacteria exhibiting multiple-antibiotic resistance. Thus, conjugation and spread of antibiotic resistance represents a severe problem in antibiotic treatment, especially of immunosuppressed patients and in intensive care units. While conjugation in gram-negative bacteria has been studied in great detail over the last decades, the transfer mechanisms of antibiotic resistance plasmids in gram-positive bacteria remained obscure. In the last few years, the entire nucleotide sequences of several large conjugative plasmids from gram-positive bacteria have been determined. Sequence analyses and data bank comparisons of their putative transfer (tra) regions have revealed significant similarities to tra regions of plasmids from gram-negative bacteria with regard to the respective DNA relaxases and their targets, the origins of transfer (oriT), and putative nucleoside triphosphatases NTP-ases with homologies to type IV secretion systems. In contrast, a single gene encoding a septal DNA translocator protein is involved in plasmid transfer between micelle-forming streptomycetes. Based on these clues, we propose the existence of two fundamentally different plasmid-mediated conjugative mechanisms in gram-positive microorganisms, namely, the mechanism taking place in unicellular gram-positive bacteria, which is functionally similar to that in gram-negative bacteria, and a second type that occurs in multicellular gram-positive bacteria, which seems to be characterized by double-stranded DNA transfer.

Grohmann, Elisabeth; Muth, Gunther; Espinosa, Manuel

2003-01-01

4

Protein secretion and surface display in Gram-positive bacteria  

PubMed Central

The cell wall peptidoglycan of Gram-positive bacteria functions as a surface organelle for the transport and assembly of proteins that interact with the environment, in particular, the tissues of an infected host. Signal peptide-bearing precursor proteins are secreted across the plasma membrane of Gram-positive bacteria. Some precursors carry C-terminal sorting signals with unique sequence motifs that are cleaved by sortase enzymes and linked to the cell wall peptidoglycan of vegetative forms or spores. The sorting signals of pilin precursors are cleaved by pilus-specific sortases, which generate covalent bonds between proteins leading to the assembly of fimbrial structures. Other precursors harbour surface (S)-layer homology domains (SLH), which fold into a three-pronged spindle structure and bind secondary cell wall polysaccharides, thereby associating with the surface of specific Gram-positive microbes. Type VII secretion is a non-canonical secretion pathway for WXG100 family proteins in mycobacteria. Gram-positive bacteria also secrete WXG100 proteins and carry unique genes that either contribute to discrete steps in secretion or represent distinctive substrates for protein transport reactions.

Schneewind, Olaf; Missiakas, Dominique M.

2012-01-01

5

Regulation of nitrogen metabolism in gram-positive bacteria  

Microsoft Academic Search

A search for new members of the TnrA and GlnR regulons, responsible for assimilation of nitrogen in Gram-positive bacteria,\\u000a was performed. Common regulatory signals with consensus sequences ATGTNAWWWWWWWTNACAT and TGTNAWWWWWWWTNACA were identified\\u000a for GlnR and TnrA, respectively. The structure was described and new potential members were found in Bacillus subtilis, B. licheniformis, Geobacillus kaustophilus, and Oceanobacillus iheyensis for the TnrA\\/GlnR

N. A. Doroshchuk; M. S. Gelfand; D. A. Rodionov

2006-01-01

6

Conjugative type IV secretion systems in Gram-positive bacteria  

PubMed Central

Bacterial conjugation presents the most important means to spread antibiotic resistance and virulence factors among closely and distantly related bacteria. Conjugative plasmids are the mobile genetic elements mainly responsible for this task. All the genetic information required for the horizontal transmission is encoded on the conjugative plasmids themselves. Two distinct concepts for horizontal plasmid transfer in Gram-positive bacteria exist, the most prominent one transports single stranded plasmid DNA via a multi-protein complex, termed type IV secretion system, across the Gram-positive cell envelope. Type IV secretion systems have been found in virtually all unicellular Gram-positive bacteria, whereas multicellular Streptomycetes seem to have developed a specialized system more closely related to the machinery involved in bacterial cell division and sporulation, which transports double stranded DNA from donor to recipient cells. This review intends to summarize the state of the art of prototype systems belonging to the two distinct concepts; it focuses on protein key players identified so far and gives future directions for research in this emerging field of promiscuous interbacterial transport.

Goessweiner-Mohr, Nikolaus; Arends, Karsten; Keller, Walter; Grohmann, Elisabeth

2013-01-01

7

[Regulation of nitrogen metabolism in gram-positive bacteria].  

PubMed

We searched for new members of the TnrA and GlnR regulons controlling assimilation of nitrogen in gram-positive bacteria. We identified the regulatory signals for these transcription factors with consensuses ATGTNAWWWWWWWTNACAT for GlnR and TGTNAWWWWWWWTNACA for TnrA. We described the structure and found new potential members for the TnrA/GlnR regulons in Bacillus subtilis, B. licheniformis, Geobacillus kaustophilus, Oceanobacillus iheyensis, for the TnrA regulon in B. halodurans and for the GlnR regulons in Lactococcus lactis, Lactobacillus plantarum, Streptococcus pyogenes, S. pneumoniae, S. mutans, S. agalactiae, Enterococcus faecalis, Listeria monocytogenes, Staphylococcus aureus and St. epidermidis. PMID:17086994

Doroshchuk, N A; Gel'fand, M S; Rodionov, D A

2006-01-01

8

New thermosensitive plasmid for gram-positive bacteria.  

PubMed Central

We isolated a replication-thermosensitive mutant of the broad-host-range replicon pWV01. The mutant pVE6002 is fully thermosensitive above 35 degrees C in both gram-negative and gram-positive bacteria. Four clustered mutations were identified in the gene encoding the replication protein of pVE6002. The thermosensitive derivative of the related plasmid pE194 carries a mutation in the analogous region but not in the same position. Derivatives of the thermosensitive plasmid convenient for cloning purposes have been constructed. The low shut-off temperature of pVE6002 makes it a useful suicide vector for bacteria which are limited in their own temperature growth range. Using pVE6002 as the delivery vector for a transposon Tn10 derivative in Bacillus subtilis, we observed transposition frequencies of about 1%. Images

Maguin, E; Duwat, P; Hege, T; Ehrlich, D; Gruss, A

1992-01-01

9

Type IV pili in Gram-positive bacteria.  

PubMed

Type IV pili (T4P) are surface-exposed fibers that mediate many functions in bacteria, including locomotion, adherence to host cells, DNA uptake (competence), and protein secretion and that can act as nanowires carrying electric current. T4P are composed of a polymerized protein, pilin, and their assembly apparatuses share protein homologs with type II secretion systems in eubacteria and the flagella of archaea. T4P are found throughout Gram-negative bacterial families and have been studied most extensively in certain model Gram-negative species. Recently, it was discovered that T4P systems are also widespread among Gram-positive species, in particular the clostridia. Since Gram-positive and Gram-negative bacteria have many differences in cell wall architecture and other features, it is remarkable how similar the T4P core proteins are between these organisms, yet there are many key and interesting differences to be found as well. In this review, we compare the two T4P systems and identify and discuss the features they have in common and where they differ to provide a very broad-based view of T4P systems across all eubacterial species. PMID:24006467

Melville, Stephen; Craig, Lisa

2013-09-01

10

Regulation of Apoptosis by Gram-Positive Bacteria  

PubMed Central

Apoptosis, or programmed cell death (PCD), is an important physiological mechanism, through which the human immune system regulates homeostasis and responds to diverse forms of cellular damage. PCD may also be involved in immune counteraction to microbial infection. Over the past decade, the amount of research on bacteria-induced PCD has grown tremendously, and the implications of this mechanism on immunity are being elucidated. Some pathogenic bacteria actively trigger the suicide response in critical lineages of leukocytes that orchestrate both the innate and adaptive immune responses; other bacteria proactively prevent PCD to benefit their own survival and persistence. Currently, the microbial virulence factors, which represent the keys to unlocking the suicide response in host cells, are a primary focus of this field. In this review, we discuss these bacterial “apoptosis regulatory molecules” and the apoptotic events they either trigger or prevent, the host target cells of this regulatory activity, and the possible ramifications for immunity to infection. Gram-positive pathogens including Staphylococcus, Streptococcus, Bacillus, Listeria, and Clostridia species are discussed as important agents of human infection that modulate PCD pathways in eukaryotic cells.

Ulett, Glen C.; Adderson, Elisabeth E.

2008-01-01

11

A Comparative Genome Analysis Identifies Distinct Sorting Pathways in Gram-Positive Bacteria  

Microsoft Academic Search

Surface proteins in gram-positive bacteria are frequently required for virulence, and many are attached to the cell wall by sortase enzymes. Bacteria frequently encode more than one sortase enzyme and an even larger number of potential sortase substrates that possess an LPXTG-type cell wall sorting signal. In order to elucidate the sorting pathways present in gram-positive bacteria, we performed a

David Comfort; Robert T. Clubb

2004-01-01

12

Phylogenetic diversity of Gram-positive bacteria cultured from Antarctic deep-sea sponges  

Microsoft Academic Search

Gram-positive bacteria, specifically actinobacteria and members of the order Bacillales, are well-known producers of important\\u000a secondary metabolites. Little is known about the diversity of Gram-positive bacteria associated with Antarctic deep-sea sponges.\\u000a In this study, cultivation-based approaches were applied to investigate the Gram-positive bacteria associated with the Antarctic\\u000a sponges Rossella nuda, Rossella racovitzae (Porifera: Hexactinellida), and Myxilla mollis, Homaxinella balfourensis, Radiella

Yanjuan Xin; Manmadhan Kanagasabhapathy; Dorte Janussen; Song Xue; Wei Zhang

13

Were Gram-positive rods the first bacteria?  

Microsoft Academic Search

At some point in the evolution of life, the domain Bacteria arose from prokaryotic progenitors. The cell that gave rise to the first bacterium has been given the name (among several other names) ‘last universal ancestor (LUA)’. This cell had an extensive, well-developed suite of biochemical strategies that increased its ability to grow. The first bacterium is thought to have

Arthur L. Koch

2003-01-01

14

Regulation of innate and adaptive immune responses by Gram-positive and Gram-negative bacteria  

Microsoft Academic Search

Bacteria are classified as Gram-positive or Gram-negative, depending on their cell wall structure. The role of the bacterial cell wall in immune regulation is the focus of the current work. Most Gram-positive bacteria stimulate monocytes to produce large amounts of IL-12. IL-12 induces production of IFN-? in T cells and NK cells, which, in turn, activates the bactericidal capacity of

Anna Martner

15

Acquired inducible antimicrobial resistance in Gram-positive bacteria  

PubMed Central

A major contributor to the emergence of antibiotic resistance in Gram-positive bacterial pathogens is the expansion of acquired, inducible genetic elements. Although acquired, inducible antibiotic resistance is not new, the interest in its molecular basis has been accelerated by the widening distribution and often ‘silent’ spread of the elements responsible, the diagnostic challenges of such resistance and the mounting limitations of available agents to treat Gram-positive infections. Acquired, inducible antibiotic resistance elements belong to the accessory genome of a species and are horizontally acquired by transformation/recombination or through the transfer of mobile DNA elements. The two key, but mechanistically very different, induction mechanisms are: ribosome-sensed induction, characteristic of the macrolide–lincosamide–streptogramin B antibiotics and tetracycline resistance, leading to ribosomal modifications or efflux pump activation; and resistance by cell surface-associated sensing of ?-lactams (e.g., oxacillin), glycopeptides (e.g., vancomycin) and the polypeptide bacitracin, leading to drug inactivation or resistance due to cell wall alterations.

Chancey, Scott T; Zahner, Dorothea; Stephens, David S

2012-01-01

16

Polyhydroxyalkanoates in Gram-positive bacteria: insights from the genera Bacillus and Streptomyces  

Microsoft Academic Search

Gram-positive bacteria, notably Bacillus and Streptomyces, have been used extensively in industry. However, these microorganisms have not yet been exploited for the production of the biodegradable polymers, polyhydroxyalkanoates (PHAs). Although PHAs have many potential applications, the cost of production means that medical applications are currently the main area of use. Gram-negative bacteria, currently the only commercial source of PHAs, have

Sabeel P. Valappil; Aldo R. Boccaccini; Christopher Bucke; Ipsita Roy

2007-01-01

17

Interaction of Cationic Peptides with Lipoteichoic Acid and Gram-Positive Bacteria  

PubMed Central

Compounds with antiendotoxin properties have been extensively studied for their potential as therapeutic agents for sepsis attributable to gram-negative bacteria. However, with the increasing incidence of gram-positive sepsis, there is interest in identifying compounds with a broad spectrum of action against both gram-positive and gram-negative bacteria. A series of synthetic ?-helical cationic peptides related to bee melittin and silk moth cecropin have previously been shown to bind lipopolysaccharide (LPS) with high affinity, inhibit LPS-induced tumor necrosis factor alpha (TNF-?) production in vitro and in vivo, and kill gram-negative bacteria. In this study, we analyzed whether these peptides were active against gram-positive bacteria; whether they could bind to lipoteichoic acid (LTA), the major proinflammatory structure on gram-positive bacteria; and whether they could block the ability of LTA to promote the release of cytokines by the RAW 264.7 murine macrophage cell line. We found that the cationic peptides demonstrated moderate growth-inhibitory activity toward gram-positive bacteria. In addition, the peptides bound LTA with high affinity. This correlated with the ability of the peptides to block LTA-induced production of TNF and interleukin-6 by RAW 264.7 cells but did not correlate with their ability to kill the bacteria. The peptides also effectively inhibited LTA-induced TNF production in a whole human blood assay. The peptides were also able to partly block the ability of heat-killed Staphylococcus aureus, as well as soluble products of live S. aureus, to stimulate cytokine production by macrophages. Our results indicate that these cationic peptides may be useful to prevent sepsis and inflammation caused by both gram-negative and gram-positive bacteria.

Scott, Monisha G.; Gold, Michael R.; Hancock, Robert E. W.

1999-01-01

18

Salusin-?, an Antimicrobially Active Peptide against Gram-Positive Bacteria.  

PubMed

Salusin-? has been detected in numerous mammalian tissues and has been shown to have various effects on the cardiovascular system. In this study, we showed that salusin-? exhibited potent antibacterial activity against Gram-positive microorganisms such as Bacillus subtilis NBRC 3513, Bacillus megaterium ATCC 19213, Staphylococcus aureus NBRC 12732, and Staphylococcus epidermidis NBRC 12933. A cytoplasmic membrane-depolarizing assay using the DiSC3(5) dye revealed that the addition of 4?nmol/mL of salusin-? caused the leakage of fluorescence dye from Staphylococcus aureus NBRC 12732. The antimicrobial potency and circular dichroism (CD) spectroscopy of five analogs related to salusin-? were examined to determine structure-function relationships in its N- and C-terminal regions. The results obtained suggest that the N-terminal sequences of the salusin-? molecule are important for the expression of the potent antimicrobial activity of this peptide. A profile corresponding to that of the ?-helix conformation was observed in the salusin-? solution. PMID:24881665

Kimura, Masahiro; Shindo, Mitsuno; Moriizumi, Toshiyuki; Tagawa, Noriko; Fujinami, Aya; Kato, Ikuo; Uchida, Yoshiki

2014-01-01

19

Multidrug resistance in hydrocarbon-tolerant Gram-positive and Gram-negative bacteria.  

PubMed

New Gram-positive and Gram-negative bacteria were isolated from Poeni oily sludge, using enrichment procedures. The six Gram-positive strains belong to Bacillus, Lysinibacillus and Rhodococcus genera. The eight Gram-negative strains belong to Shewanella, Aeromonas, Pseudomonas and Klebsiella genera. Isolated bacterial strains were tolerant to saturated (i.e., n-hexane, n-heptane, n-decane, n-pentadecane, n-hexadecane, cyclohexane), monoaromatic (i.e., benzene, toluene, styrene, xylene isomers, ethylbenzene, propylbenzene) and polyaromatic (i.e., naphthalene, 2-methylnaphthalene, fluorene) hydrocarbons, and also resistant to different antimicrobial agents (i.e., ampicillin, kanamycin, rhodamine 6G, crystal violet, malachite green, sodium dodecyl sulfate). The presence of hydrophilic antibiotics like ampicillin or kanamycin in liquid LB-Mg medium has no effects on Gram-positive and Gram-negative bacteria resistance to toxic compounds. The results indicated that Gram-negative bacteria are less sensitive to toxic compounds than Gram-positive bacteria, except one bacteria belonging to Lysinibacillus genus. There were observed cellular and molecular modifications induced by ampicillin or kanamycin to isolated bacterial strains. Gram-negative bacteria possessed between two and four catabolic genes (alkB, alkM, alkB/alkB1, todC1, xylM, PAH dioxygenase, catechol 2,3-dioxygenase), compared with Gram-positive bacteria (except one bacteria belonging to Bacillus genus) which possessed one catabolic gene (alkB/alkB1). Transporter genes (HAE1, acrAB) were detected only in Gram-negative bacteria. PMID:21478643

Stancu, Mihaela Marilena; Grifoll, Magdalena

2011-01-01

20

Vancomycin-resistant gram-positive bacteria isolated from human sources.  

PubMed Central

Recent reports of infections with vancomycin-resistant gram-positive bacteria prompted us to study vancomycin-resistant isolates from human sources to characterize the types of bacteria displaying this phenotype. Thirty-six vancomycin-resistant gram-positive isolates, 14 from clinical specimens and 22 from stool samples, were identified. These isolates were tentatively identified as Lactobacillus spp. (25 strains), Leuconostoc spp. (6 strains), and Pediococcus spp. (3 strains) on the basis of morphology and physiological tests. Two isolates of indeterminate morphology could not be unambiguously assigned to a genus. Four isolates of vancomycin-resistant lactobacilli from normally sterile body sites were considered to be clinically significant. Vancomycin-resistant gram-positive bacteria may represent an emerging class of nosocomial pathogens. Better methods for distinguishing the various genera in the clinical microbiology laboratory are needed.

Ruoff, K L; Kuritzkes, D R; Wolfson, J S; Ferraro, M J

1988-01-01

21

Sec-secretion and sortase-mediated anchoring of proteins in Gram-positive bacteria.  

PubMed

Signal peptide-driven secretion of precursor proteins directs polypeptides across the plasma membrane of bacteria. Two pathways, Sec- and SRP-dependent, converge at the SecYEG translocon to thread unfolded precursor proteins across the membrane, whereas folded preproteins are routed via the Tat secretion pathway. Gram-positive bacteria lack an outer membrane and are surrounded by a rigid layer of peptidoglycan. Interactions with their environment are mediated by proteins that are retained in the cell wall, often through covalent attachment to the peptidoglycan. In this review, we describe the mechanisms for both Sec-dependent secretion and sortase-dependent assembly of proteins in the envelope of Gram-positive bacteria. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey. PMID:24269844

Schneewind, Olaf; Missiakas, Dominique

2014-08-01

22

Ubiquitous Detection of Gram-Positive Bacteria with Bioorthogonal Magnetofluorescent Nanoparticles  

PubMed Central

The ability to rapidly diagnose gram-positive pathogenic bacteria would have far reaching biomedical and technological applications. Here we describe the bioorthogonal modification of small molecule antibiotics (vancomycin and daptomycin), which bind to the cell wall of gram-positive bacteria. The bound antibiotics conjugates can be reacted orthogonally with tetrazine-modified nanoparticles, via an almost instantaneous cycloaddition, which subsequently renders the bacteria detectable by optical or magnetic sensing. We show that this approach is specific, selective, fast and biocompatible. Furthermore, it can be adapted to the detection of intracellular pathogens. Importantly, this strategy enables detection of entire classes of bacteria, a feat that is difficult to achieve using current antibody approaches. Compared to covalent nanoparticle conjugates, our bioorthogonal method demonstrated 1-2 orders of magnitude greater sensitivity. This bioorthogonal labeling method could ultimately be applied to a variety of other small molecules with specificity for infectious pathogens, enabling their detection and diagnosis.

Chung, Hyun Jung; Reiner, Thomas; Budin, Ghyslain; Min, Changwook; Liong, Monty; Issadore, David; Lee, Hakho; Weissleder, Ralph

2011-01-01

23

Cell to cell communication by autoinducing peptides in gram-positive bacteria  

Microsoft Academic Search

While intercellular communication systems in Gram-negative bacteria are often based on homoserine lactones as signalling molecules,\\u000a it has been shown that autoinducing peptides are involved in intercellular communication in Gram-positive bacteria. Many of\\u000a these peptides are exported by dedicated systems, posttranslationally modified in various ways, and finally sensed by other\\u000a cells via membrane-located receptors that are part of two-component regulatory

Mark H. J. Sturme; Michiel Kleerebezem; Jiro Nakayama; Antoon D. L. Akkermans; Elaine E. Vaughan; Willem M. de Vos

2002-01-01

24

Drosophila Toll is activated by Gram-positive bacteria through a circulating peptidoglycan recognition protein  

Microsoft Academic Search

Microbial infection activates two distinct intracellular signalling cascades in the immune-responsive fat body of Drosophila. Gram-positive bacteria and fungi predominantly induce the Toll signalling pathway, whereas Gram-negative bacteria activate the Imd pathway. Loss-of-function mutants in either pathway reduce the resistance to corresponding infections. Genetic screens have identified a range of genes involved in these intracellular signalling cascades, but how they

Tatiana Michel; Jean-Marc Reichhart; Jules A. Hoffmann; Julien Royet

2001-01-01

25

Distinct localization of the complement C5b-9 complex on Gram-positive bacteria.  

PubMed

The plasma proteins of the complement system fulfil important immune defence functions, including opsonization of bacteria for phagocytosis, generation of chemo-attractants and direct bacterial killing via the Membrane Attack Complex (MAC or C5b-9). The MAC is comprised of C5b, C6, C7, C8, and multiple copies of C9 that generate lytic pores in cellular membranes. Gram-positive bacteria are protected from MAC-dependent lysis by their thick peptidoglycan layer. Paradoxically, several Gram-positive pathogens secrete small proteins that inhibit C5b-9 formation. In this study, we found that complement activation on Gram-positive bacteria in serum results in specific surface deposition of C5b-9 complexes. Immunoblotting revealed that C9 occurs in both monomeric and polymeric (SDS-stable) forms, indicating the presence of ring-structured C5b-9. Surprisingly, confocal microscopy demonstrated that C5b-9 deposition occurs at specialized regions on the bacterial cell. On Streptococcus pyogenes, C5b-9 deposits near the division septum whereas on Bacillus subtilis the complex is located at the poles. This is in contrast to C3b deposition, which occurs randomly on the bacterial surface. Altogether, these results show a previously unrecognized interaction between the C5b-9 complex and Gram-positive bacteria, which might ultimately lead to a new model of MAC assembly and functioning. PMID:23869880

Berends, Evelien T M; Dekkers, Johanna F; Nijland, Reindert; Kuipers, Annemarie; Soppe, Jasper A; van Strijp, Jos A G; Rooijakkers, Suzan H M

2013-12-01

26

Microarray-Based Detection of 90 Antibiotic Resistance Genes of Gram-Positive Bacteria  

Microsoft Academic Search

A disposable microarray was developed for detection of up to 90 antibiotic resistance genes in gram-positive bacteria by hybridization. Each antibiotic resistance gene is represented by two specific oligonucleotides chosen from consensus sequences of gene families, except for nine genes for which only one specific oligonucleotide could be developed. A total of 137 oligonucleotides (26 to 33 nucleotides in length

Vincent Perreten; Lorianne Vorlet-Fawer; Peter Slickers; Ralf Ehricht; Peter Kuhnert; Joachim Frey

2005-01-01

27

A rapid procedure for isolating chromosomal DNA from Lactobacillus species and other Gram-positive bacteria  

Microsoft Academic Search

R. L. U L R I C H A N D T. A. H U G H E S. 2001. This study describes a rapid procedure for the isolation of genomic DNA from various Gram-positive bacteria. Species tested included Lactobacillus delbrueckii subsp. lactis ATCC 4797, Lact. acidophilus N2, Staphylococcus aureus, Staph. epidermidis, Propionibacterium jensenii P126, Bacillus pumilus and Enterococcus faecalis.

R. L. Ulrich; T. A. Hughes

2001-01-01

28

Gram-positive pathogenic bacteria induce a common early response in human monocytes  

Microsoft Academic Search

BACKGROUND: We infected freshly isolated human peripheral monocytes with live bacteria of three clinically important gram-positive bacterial species, Staphylococcus aureus, Streptococcus pneumoniae and Listeria monocytogenes and studied the ensuing early transcriptional response using expression microarrays. Thus the observed response was unbiased by signals originating from other helper and effector cells of the host and was not limited to induction by

Svetlin Tchatalbachev; Rohit Ghai; Hamid Hossain; Trinad Chakraborty

2010-01-01

29

Electrochemical classification of gram-negative and gram-positive bacteria.  

PubMed Central

Intestinal bacteria were classified as gram-positive or gram-negative by an electrode system with a basal plane pyrolytic graphite electrode and a porous nitrocellulose membrane filter to trap bacteria. When the potential of the graphite electrode was run in the range of 0 to 1.0 V versus the saturated calomel electrode (SCE), gram-positive bacteria gave peak currents at 0.65 to 0.69 V versus the SCE. The peak potentials of gram-negative bacteria were 0.70 to 0.74 V versus the SCE. Gram-negative bacteria and gram-positive bacteria were also classified based on the ratio of the second peak current to the first peak current when the potential cycle was repeated twice. The numbers of cells on the membrane filter were determined from the peak currents. It was found that the peak currents result from the electrochemical oxidation of coenzyme A in the cells of Escherichia coli and Lactobacillus acidophilus. Images

Matsunaga, T; Nakajima, T

1985-01-01

30

A Comparative Genome Analysis Identifies Distinct Sorting Pathways in Gram-Positive Bacteria  

PubMed Central

Surface proteins in gram-positive bacteria are frequently required for virulence, and many are attached to the cell wall by sortase enzymes. Bacteria frequently encode more than one sortase enzyme and an even larger number of potential sortase substrates that possess an LPXTG-type cell wall sorting signal. In order to elucidate the sorting pathways present in gram-positive bacteria, we performed a comparative analysis of 72 sequenced microbial genomes. We show that sortase enzymes can be partitioned into five distinct subfamilies based upon their primary sequences and that most of their substrates can be predicted by making a few conservative assumptions. Most bacteria encode sortases from two or more subfamilies, which are predicted to function nonredundantly in sorting proteins to the cell surface. Only ?20% of sortase-related proteins are most closely related to the well-characterized Staphylococcus aureus SrtA protein, but nonetheless, these proteins are responsible for anchoring the majority of surface proteins in gram-positive bacteria. In contrast, most sortase-like proteins are predicted to play a more specialized role, with each anchoring far fewer proteins that contain unusual sequence motifs. The functional sortase-substrate linkage predictions are available online (http://www.doe-mbi.ucla.edu/Services/Sortase/) in a searchable database.

Comfort, David; Clubb, Robert T.

2004-01-01

31

[Susceptibility of clinical strains of gram-positive bacteria to selected beta-lactam antibiotics].  

PubMed

The aim of the study was to determine the activity of four beta-lactam antibiotics against nosocomial strains of Gram-positive bacteria. Two antibiotics combined with beta-lactamase inhibitors: timentin (TIC/CLAV) and tazocin (PIP/TZB) and two carbapenems: imipenem and meropenem were applied. The clinical strains were isolated from patients hospitalized in surgical ward of the National Clinical Hospital No 1 in Warsaw. The strains were identified in the automatic ATB system using ID 32 STAPH, API STREP, API CORYNE and API 20 A strips. The susceptibility of isolates to antibacterial agents was determined in the automatic ATB system using ATB STAPH, ATB STREP and ATB ANA strips. The susceptibility of strains to timentin, tazocin, imipenem and meropenem was tested with disc diffusion method. 111 strains of Gram-positive bacteria were cultured. Staphylococci (49) and enterococci (44) dominated among isolated strains. 33 Staphylococcus spp. strains were identified as methicillin-resistant. The obtained results indicate a significant role of Gram-positive cocci (staphylococci and enterococci) in the aetiology of nosocomial infections. Antibiotics combined with beta-lactamase inhibitors and carbapenems demonstrate broad antibacterial spectrum against clinical strains of Gram-positive bacteria except E. faecium strains. PMID:9857616

Sawicka-Grzelak, A; Rokosz, A

1998-01-01

32

Construction and evaluation of multisite recombinatorial (Gateway) cloning vectors for Gram-positive bacteria  

PubMed Central

Background The Gateway recombinatorial cloning system allows easy and rapid joining of DNA fragments. Here we report the construction and evaluation of three different Gram-positive vectors that can be used with the Multisite Gateway cloning system to rapidly produce new gene arrangements in plasmid constructs for use in a variety of Gram-positive bacteria. Results Comparison of patterns of reporter gene expression with conventionally constructed clones show that the presence of residual recombination (att) sites does not have an effect on patterns of gene expression, although overall levels of gene expression may vary. Rapid construction of these new vectors allowed vector/gene combinations to be optimized following evaluation of plasmid constructs in different bacterial cells and demonstrates the benefits of plasmid construction using Gateway cloning. Conclusion The residual att sites present after Gateway cloning did not affect patterns of promoter induction in Gram-positive bacteria and there was no evidence of differences in mRNA stability of transcripts. However overall levels of gene expression may be reduced, possibly due to some post-transcriptional event. The new vectors described here allow faster, more efficient cloning in range of Gram-positive bacteria.

Perehinec, Tania M; Qazi, Saara NA; Gaddipati, Sanyasi R; Salisbury, Vyvyan; Rees, Catherine ED; Hill, Philip J

2007-01-01

33

Multiple Responses of Gram-Positive and Gram-Negative Bacteria to Mixture of Hydrocarbons  

PubMed Central

Most of our knowledge about pollutants and the way they are biodegraded in the environment has previously been shaped by laboratory studies using hydrocarbon-degrading bacterial strains isolated from polluted sites. In present study Gram-positive (Mycobacterium sp. IBBPo1, Oerskovia sp. IBBPo2, Corynebacterium sp. IBBPo3) and Gram-negative (Chryseomonas sp. IBBPo7, Pseudomonas sp. IBBPo10, Burkholderia sp. IBBPo12) bacteria, isolated from oily sludge, were found to be able to tolerate pure and mixture of saturated hydrocarbons, as well as pure and mixture of monoaromatic and polyaromatic hydrocarbons. Isolated Gram-negative bacteria were more tolerant to mixture of saturated (n-hexane, n-hexadecane, cyclohexane), monoaromatic (benzene, toluene, ethylbenzene) and polyaromatic (naphthalene, 2-methylnaphthalene, fluorene) hydrocarbons than Gram-positive bacteria. There were observed cellular and molecular modifications induced by mixture of saturated, monoaromatic and polyaromatic hydrocarbons to Gram-positive and Gram-negative bacteria. These modifications differ from one strain to another and even for the same bacterial strain, according to the nature of hydrophobic substrate.

Marilena Lazaroaie, Mihaela

2010-01-01

34

Volatile organic compound analysis by ion molecule reaction mass spectrometry for Gram-positive bacteria differentiation.  

PubMed

Approximately 50 % of all clinically proven infections in critically ill patients are caused by Gram-positive bacteria. The timely and appropriate treatment of these infections is vital in order to avoid negative outcomes. Hence, fast and reliable methods are needed for the early detection and identification of microorganisms. Recently, direct mass spectrometry-based analysis of volatile organic compounds emitted by microorganisms has been employed to study Gram-negative bacteria. Here, we report a feasibility study of ion molecule reaction mass spectrometry (IMR-MS) for in vitro growth detection and species differentiation of selected Gram-positive bacteria that are frequently isolated in blood culture samples, namely, Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, and Staphylococcus epidermidis. Ion molecule reaction mass spectrometry was used to analyze the headspace above cultures containing Gram-positive bacteria incubated at 37 °C starting with 10(2) colony-forming units (CFU)/ml. Measurements to determine the presence of volatile organic compounds were performed 4, 8, and 24 h after incubation, respectively. The detection of microbial growth was accomplished already after 8 h in cultures containing E. faecalis. After 24 h of incubation, characteristic mass spectra were obtained for all species. Processing these mass spectra by hierarchic clustering and principal component analysis (PCA) enabled us to differentiate between bacterial species. IMR-MS in conjunction with a cumulative end-point model provides the means for rapid growth detection and differentiation of Gram-positive bacteria on the species level, typically within an analysis time of less than 3 min per sample. PMID:22782437

Dolch, M E; Hornuss, C; Klocke, C; Praun, S; Villinger, J; Denzer, W; Schelling, G; Schubert, S

2012-11-01

35

Lipoteichoic acids, phosphate-containing polymers in the envelope of gram-positive bacteria.  

PubMed

Lipoteichoic acids (LTA) are polymers of alternating units of a polyhydroxy alkane, including glycerol and ribitol, and phosphoric acid, joined to form phosphodiester units that are found in the envelope of Gram-positive bacteria. Here we review four different types of LTA that can be distinguished on the basis of their chemical structure and describe recent advances in the biosynthesis pathway for type I LTA, d-alanylated polyglycerol-phosphate linked to di-glucosyl-diacylglycerol. The physiological functions of type I LTA are discussed in the context of inhibitors that block their synthesis and of mutants with discrete synthesis defects. Research on LTA structure and function represents a large frontier that has been investigated in only few Gram-positive bacteria. PMID:24415723

Schneewind, Olaf; Missiakas, Dominique

2014-03-01

36

Comparative in vitro activity of levofloxacin and ofloxacin against Gram-positive bacteria  

Microsoft Academic Search

The in vitro activity of levofloxacin against 506 Gram-positive bacteria was compared with those of D(?)-ofloxacin, ofloxacin, ciprofloxacin, and sparfloxacin. Levofloxacin was generally twice as active as ofloxacin against these organisms (range, 0–3 twofold dilutions). Sparfloxacin appeared to have the greatest activity overall, but for several groups of organisms minimum inhibitory concentrations (MIC90s) of this com pound were within one

George M. Eliopoulos; Christine B. Wennersten; Robert C. Moellering

1996-01-01

37

Plasmid vectors for Gram-positive bacteria switching from high to low copy number  

Microsoft Academic Search

A set of vectors for Gram-positive bacteria was constructed with a new feature which enables the switching down of their copy number per cell. These vectors carry the replication region of pAM?1, containing a gene essential for replication, repE, and its regulator, copF The latter gene was inactivated by inserting a linker into its unique KpnI site. Since copF downregulates

Pierre Renault; Gerard Corthier; Nathalie Goupil; Christine Delorme; S. Dusko Ehrlich

1996-01-01

38

Widespread Abundance of Functional Bacterial Amyloid in Mycolata and Other Gram-Positive Bacteria?  

PubMed Central

Until recently, extracellular functional bacterial amyloid (FuBA) has been detected and characterized in only a few bacterial species, including Escherichia coli, Salmonella, and the gram-positive organism Streptomyces coelicolor. Here we probed gram-positive bacteria with conformationally specific antibodies and revealed the existence of FuBA in 12 of 14 examined mycolata species, as well as six other distantly related species examined belonging to the phyla Actinobacteria and Firmicutes. Most of the bacteria produced extracellular fimbriae, sometimes copious amounts of them, and in two cases large extracellular fibrils were also produced. In three cases, FuBA was revealed only after extensive removal of extracellular material by saponification, indicating that there is integrated attachment within the cellular envelope. Spores of species in the genera Streptomyces, Bacillus, and Nocardia were all coated with amyloids. FuBA was purified from Gordonia amarae (from the cell envelope) and Geodermatophilus obscurus, and they had the morphology, tinctorial properties, and ?-rich structure typical of amyloid. The presence of approximately 9-nm-wide amyloids in the cell envelope of G. amarae was visualized by transmission electron microscopy analysis. We conclude that amyloid is widespread among gram-positive bacteria and may in many species constitute a hitherto overlooked integral part of the spore and the cellular envelope.

Jordal, Peter Bruun; Dueholm, Morten Simonsen; Larsen, Poul; Petersen, Steen Vang; Enghild, Jan Johannes; Christiansen, Gunna; H?jrup, Peter; Nielsen, Per Halkjaer; Otzen, Daniel Erik

2009-01-01

39

Surface-conjugated antimicrobial peptide leucocin a displays high binding to pathogenic gram-positive bacteria.  

PubMed

Leucocin A, a representative class IIa bacteriocin, is a ribosomally synthesized antimicrobial peptide (AMP) that displays potent activity against specific gram-positive bacteria. The antibacterial activity of such peptides is preceded by the binding event that can be utilized for studying specific peptide-bacteria interactions. In this study, 37-residue Leucocin A (LeuA) was synthesized using solid-phase peptide synthesis and covalently immobilized on gold substrates from either the N- or C-terminal. Both the peptide monolayers on gold substrates were incubated separately with five strains of gram-positive bacteria and displayed differential binding to different strains with highest binding to pathogenic Listeria monocytogenes . The C-terminally immobilized LeuA showed higher bacterial binding compared to the N-terminally attached LeuA. The full length immobilized LeuA (37-residue) was active as well as displayed higher bacterial binding (73 ± 6 bacteria/100 ?m(2)) compared to 24-residue inactive LeuA fragment (40 ± 8 bacteria/100 ?m(2)) from the C-terminal region. The high and specific bacterial binding ability of LeuA functionalized surfaces support the potential use of class IIa bacteriocins in antimicrobial peptide-based diagnostic platforms. PMID:24359454

Etayash, Hashem; Norman, Lana; Thundat, Thomas; Stiles, Michael; Kaur, Kamaljit

2014-01-22

40

Comparative genomics of the methionine metabolism in Gram-positive bacteria: a variety of regulatory systems.  

PubMed

Regulation of the methionine biosynthesis and transport genes in bacteria is rather diverse and involves two RNA-level regulatory systems and at least three DNA-level systems. In particular, the methionine metabolism in Gram-positive bacteria was known to be controlled by the S-box and T-box mechanisms, both acting on the level of premature termination of transcription. Using comparative analysis of genes, operons and regulatory elements, we described the methionine metabolic pathway and the methionine regulons in available genomes of Gram-positive bacteria. A large number of methionine-specific RNA elements were identified. S-boxes were shown to be widely distributed in Bacillales and Clostridia, whereas methionine-specific T-boxes occurred mostly in Lactobacillales. A candidate binding signal (MET-box) for a hypothetical methionine regulator, possibly MtaR, was identified in Streptococcaceae, the only family in the Bacillus/Clostridium group of Gram-positive bacteria having neither S-boxes, nor methionine-specific T-boxes. Positional analysis of methionine-specific regulatory sites complemented by genome context analysis lead to identification of new members of the methionine regulon, both enzymes and transporters, and reconstruction of the methionine metabolism in various bacterial genomes. In particular, we found candidate transporters for methionine (MetT) and methylthioribose (MtnABC), as well as new enzymes forming the S-adenosylmethionine recycling pathway. Methionine biosynthetic enzymes in various bacterial species are quite variable. In particular, Oceanobacillus iheyensis possibly uses a homolog of the betaine-homocysteine methyltransferase bhmT gene from vertebrates to substitute missing bacterial-type methionine synthases. PMID:15215334

Rodionov, Dmitry A; Vitreschak, Alexey G; Mironov, Andrey A; Gelfand, Mikhail S

2004-01-01

41

Transport Capabilities of Eleven Gram-positive Bacteria: Comparative Genomic Analyses  

PubMed Central

The genomes of eleven Gram-positive bacteria that are important for human health and the food industry, nine low G+C lactic acid bacteria and two high G+C Gram-positive organisms, were analyzed for their complement of genes encoding transport proteins. Thirteen to eighteen percent of their genes encode transport proteins, larger percentages than observed for most other bacteria. All of these bacteria possess channel proteins, some of which probably function to relieve osmotic stress. Amino acid uptake systems predominate over sugar and peptide cation symporters, and of the sugar uptake porters, those specific for oligosaccharides and glycosides often outnumber those for free sugars. About 10% of the total transport proteins are constituents of putative multidrug efflux pumps with Major Facilitator Superfamily (MFS)-type pumps (55%) being more prevalent than ATP-binding cassette (ABC)-type pumps (33%), which, however, usually greatly outnumber all other types. An exception to this generalization is Streptococcus thermophilus with 54% of its drug efflux pumps belonging to the ABC superfamily and 23% belonging each to the Multidrug/Oligosaccharide/Polysaccharide (MOP) superfamily and the MFS. These bacteria also display peptide efflux pumps that may function in intercellular signalling, and macromolecular efflux pumps, many of predictable specificities. Most of the bacteria analyzed have no pmf-coupled or transmembrane flow electron carriers. The one exception is Brevibacterium linens, which in addition to these carriers, also has transporters of several families not represented in the other ten bacteria examined. Comparisons with the genomes of organisms from other bacterial kingdoms revealed that lactic acid bacteria possess distinctive proportions of recognized transporter types (e.g., more porters specific for glycosides than reducing sugars). Some homologues of transporters identified had previously been identified only in Gram-negative bacteria or in eukaryotes. Our studies reveal unique characteristics of the lactic acid bacteria such as the universal presence of genes encoding mechanosensitive channels, competence systems and large numbers of sugar transporters of the phosphotransferase system. The analyses lead to important physiological predictions regarding the preferred signalling and metabolic activities of these industrially important bacteria.

Lorca, Graciela L.; Barabote, Ravi D.; Zlotopolski, Vladimir; Tran, Can; Winnen, Brit; Hvorup, Rikki N.; Stonestrom, Aaron J.; Nguyen, Elizabeth; Huang, Li-Wen; Kim, David S.; Saier, Milton H.

2007-01-01

42

Novel Surface Display System for Proteins on Non-Genetically Modified Gram-Positive Bacteria  

PubMed Central

A novel display system is described that allows highly efficient immobilization of heterologous proteins on bacterial surfaces in applications for which the use of genetically modified bacteria is less desirable. This system is based on nonliving and non-genetically modified gram-positive bacterial cells, designated gram-positive enhancer matrix (GEM) particles, which are used as substrates to bind externally added heterologous proteins by means of a high-affinity binding domain. This binding domain, the protein anchor (PA), was derived from the Lactococcus lactis peptidoglycan hydrolase AcmA. GEM particles were typically prepared from the innocuous bacterium L. lactis, and various parameters for the optimal preparation of GEM particles and binding of PA fusion proteins were determined. The versatility and flexibility of the display and delivery technology were demonstrated by investigating enzyme immobilization and nasal vaccine applications.

Bosma, Tjibbe; Kanninga, Rolf; Neef, Jolanda; Audouy, Sandrine A. L.; van Roosmalen, Maarten L.; Steen, Anton; Buist, Girbe; Kok, Jan; Kuipers, Oscar P.; Robillard, George; Leenhouts, Kees

2006-01-01

43

Fluorescence studies of gram-positive and gram-negative bacteria  

NASA Astrophysics Data System (ADS)

Autofluorescence is a relatively unexplored technique for identification. It is nondestructive, noncontact, fast, and has the potential to be integrated in small handheld devices. On the other hand, the autofluorescent signal is sometimes very week, or it can be overwhelmed by the emission of a surrounding medium. We are exploring the possibility to develop an optical method for identification of the Gram-type of bacterial cultures based on the autofluorescence. We have enhanced the detectivity of a standard fluorimeter using combination of bandpass and long pass filters. In this particular study, we are investigating if the previously observed difference in the autofluorescent spectra of Gram-positive and Gram-negative bacteria is dependent on the age of the culture. We have selected two types of bacteria, Kocuria rhizophila and Alcagenes faecalis, and we have monitored in equal time intervals of their development the autofluorescence spectra. The stages of development were monitored separately by measuring the turbidity and creating a growth curve. The goal of this study is to find out if the previously observed difference in the autofluorescence spectra of Gram-positive and Gram-negative bacteria is dependent on the stage of the development of the bacterial culture.

Blust, Brittni

2012-02-01

44

Predominant Gram-Positive Bacteria in Human Feces: Numbers, Variety, and Persistence  

PubMed Central

The predominant gram-positive bacteria in 47 fecal specimens from 10 healthy men were studied by microscopic and cultural counts, by the characterization and tentative identification of isolates, and by the use of fluorescein isothiocyanate (FITC)-conjugated globulins prepared using some of the isolates. Gram-positive bacteria averaged 1010.5±0.4(sd/g (wet weight) of feces with significant variation from host to host. Characterization of 865 isolates, all strict anaerobes and carbohydrate fermenters, showed 12 to 39 distinguishable strains from each host and indicated that some strains were present the full period of about 18 months. Sixty percent of the isolates belonged to one of five types, tentatively identified with five species—Bifidobacterium adolescentis, Eubacterium aerofaciens, E. rectale, Peptostreptococcus productus, and Ruminococcus bromii. There was distinct host idiosyncrasy in the pattern of estimated counts of these five types. Certain strains resembling B. adolescentis, E. aerofaciens, and P. productus, distinguished with FITC conjugates, were resident in their hosts for many months. In direct smears each strain constituted about 1% of the total bacteria.

Gossling, Jennifer; Slack, John M.

1974-01-01

45

Homologous Recombination in Low dC + dG Gram-Positive Bacteria  

Microsoft Academic Search

Homologous recombination is a process involved in the maintenance of chromosome integrity,\\u000a in shaping the evolution of pathogens, in the resistance to antibiotic treatment, and profoundly affecting\\u000a evolution. In low dC + dG Gram-positive bacteria genetic recombination of a non-replicative\\u000a \\u000a homologous DNA, which enters into the cell via transduction or conjugation, proceeds mainly by the\\u000a double-strand break repair machinery, and this process

Humberto Sanchez; Begoña Carrasco; Silvia Ayora; Juan C. Alonso

46

Enhancement of Growth of Aerobic, Anaerobic, and Facultative Bacteria in Mixed Infections with Anaerobic and Facultative Gram-Positive Cocci,  

National Technical Information Service (NTIS)

Anaerobic and facultative gram-positive cocci (AFGPC) mixed with other bacteria are frequently recovered from infections at different sites in the body. Although many of these organisms are synergistic, the exact role of AFGPC in these infections and thei...

I. Brook

1988-01-01

47

Sonodynamic Excitation of Rose Bengal for Eradication of Gram-Positive and Gram-Negative Bacteria  

PubMed Central

Photodynamic antimicrobial chemotherapy based on photosensitizers activated by illumination is limited by poor penetration of visible light through skin and tissues. In order to overcome this problem, Rose Bengal was excited in the dark by 28?kHz ultrasound and was applied for inactivation of bacteria. It is demonstrated, for the first time, that the sonodynamic technique is effective for eradication of Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The net sonodynamic effect was calculated as a 3-4 log10 reduction in bacteria concentration, depending on the cell and the Rose Bengal concentration and the treatment time. Sonodynamic treatment may become a novel and effective form of antimicrobial therapy and can be used for low-temperature sterilization of medical instruments and surgical accessories.

Nakonechny, Faina; Nisnevitch, Michael; Nitzan, Yeshayahu; Nisnevitch, Marina

2013-01-01

48

sRNAdb: A small non-coding RNA database for gram-positive bacteria  

PubMed Central

Background The class of small non-coding RNA molecules (sRNA) regulates gene expression by different mechanisms and enables bacteria to mount a physiological response due to adaptation to the environment or infection. Over the last decades the number of sRNAs has been increasing rapidly. Several databases like Rfam or fRNAdb were extended to include sRNAs as a class of its own. Furthermore new specialized databases like sRNAMap (gram-negative bacteria only) and sRNATarBase (target prediction) were established. To the best of the authors’ knowledge no database focusing on sRNAs from gram-positive bacteria is publicly available so far. Description In order to understand sRNA’s functional and phylogenetic relationships we have developed sRNAdb and provide tools for data analysis and visualization. The data compiled in our database is assembled from experiments as well as from bioinformatics analyses. The software enables comparison and visualization of gene loci surrounding the sRNAs of interest. To accomplish this, we use a client–server based approach. Offline versions of the database including analyses and visualization tools can easily be installed locally on the user’s computer. This feature facilitates customized local addition of unpublished sRNA candidates and related information such as promoters or terminators using tab-delimited files. Conclusion sRNAdb allows a user-friendly and comprehensive comparative analysis of sRNAs from available sequenced gram-positive prokaryotic replicons. Offline versions including analysis and visualization tools facilitate complex user specific bioinformatics analyses.

2012-01-01

49

The immune response after stimulation with wall components of gram-positive bacteria and fungi.  

PubMed

Although several components of the microbial wall of gram-positive bacteria and fungi possess immunostimulatory properties, their pathogenetic role remains incompletely evaluated. The purpose of this study was to assess the basic immune status of patients susceptible to infections and their capability for cytokine production after stimulation with wall components of gram-positive bacteria and fungi. We measured serum cytokine levels as well as cytokine production after ex vivo lipoteichoic acid (LTA) and mannan stimulation of whole blood. The blood was taken from 10 healthy volunteers, 10 patients with end-stage renal disease (ESRD), 10 patients with diabetes mellitus (DM), and 10 patients on their 2nd day of stay in the Intensive Care Unit (ICU), who suffered from non septic systemic inflammatory response syndrome (SIRS) and had an APACHE II score ?25. We used 1 ?g/ml LTA and 100 ?g/ml mannan for an incubation period of 8 h to stimulate 100 ?l aliquots of whole blood. All patient groups had higher baseline values of TNF-?, IL-6, IL-1?, and IL-10 compared to the control group, but only for ICU patients the difference was statistically significant. The ratio IL-10/IL-6 was found 0.33, 0.22, and 0.96 in healthy persons, ESRD, and DM patients respectively, and 1.32 in ICU patients. In all examined groups, the levels of cytokines significantly increased after stimulation by LTA and mannan, although in severely ill patients this change was considerably smaller, possibly reflecting a state of monocytes' depression and relative hyporesponsiveness. No significant differences between the LTA and the mannan stimulation were observed. PMID:24440200

Tsigou, Evdoxia; Stavros, Aloizos; Pavlos, Myrianthefs; Stavros, Gourgiotis; Athanassios, Tsakris; George, Baltopoulos

2014-01-01

50

Biochemical characterization of Gram-positive and Gram-negative plant-associated bacteria with micro-Raman spectroscopy.  

PubMed

Raman spectra of Gram-positive and Gram-negative plant bacteria have been measured with micro-Raman spectrometers equipped with 785 and 514.5 nm lasers. The Gram-positive bacteria Microbacterium testaceum, Paenibacillus validus, and Clavibacter michiganensis subsp. michiganensis have strong carotenoid bands in the regions 1155-1157 cm(-1) and 1516-1522 cm(-1) that differentiate them from other tested Gram-negative bacteria. In the Raman spectrum of Gram-positive bacteria Bacillus megaterium excited with 785 nm laser, the Raman bands at 1157 and 1521 cm(-1) are weak in intensity compared to other Gram-positive bacteria, and these bands did not show significant resonance Raman enhancement in the spectrum recorded with 514.5 nm laser excitation. The Gram-positive bacteria could be separated from each other based on the bands associated with the in-phase C=C (v(1)) vibrations of the polyene chain of carotenoids. None of the Gram-negative bacteria tested had carotenoid bands. The bacteria in the genus Xanthomonas have a carotenoid-like pigment, xanthomonadin, identified in Xanthomonas axonopodis pv. dieffenbachiae, and it is a unique Raman marker for the bacteria. The representative bands for xanthomonadin were the C-C stretching (v(2)) vibrations of the polyene chain at 1135-1136 cm(-1) and the in-phase C=C (v(1)) vibrations of the polyene chain at 1529-1531 cm(-1), which were distinct from the carotenoid bands of other tested bacteria. The tyrosine peak in the region 1170-1175 cm(-1) was the only other marker present in Gram-negative bacteria that was absent in all tested Gram-positives. A strong-intensity exopolysaccharide-associated marker at 1551 cm(-1) is a distinguishable feature of Enterobacter cloacae. The Gram-negative Agrobacterium rhizogenes and Ralstonia solanacearum were differentiated from each other and other tested bacteria on the basis of presence or absence and relative intensities of peaks. The principal components analysis (PCA) of the spectra excited with 785 nm laser differentiated the various strains of bacteria based on the unique pigments these bacteria do or do not possess. Raman spectroscopy of diverse plant bacteria that are pathogenic and non-pathogenic to plants, and isolated from plants and soil, indicates the possibilities of using the method in understanding plant-bacterial interactions at the cellular level. PMID:20412629

Paret, Mathews L; Sharma, Shiv K; Green, Lisa M; Alvarez, Anne M

2010-04-01

51

Studies on the aminopeptidase test for the distinction of gram-negative from gram-positive bacteria  

Microsoft Academic Search

The aminopeptidase test was performed with representatives of gram-negative, gram-positive, and gram-variable bacteria. All gram-negative bacteria tested gave a positive test reaction with L-alanine-4-nitroanilide as test substrate. Representatives of the coryneform bacteria and some streptococci showed aminopeptidase activity after prolonged reaction times. A correlation between aminopeptidase activity and distinct interpeptide bridge composition in the peptidoglycan of many strains was demonstrated.

G. Cerny

1978-01-01

52

Characterization of unusual alkaliphilic gram-positive bacteria isolated from degraded brown alga thalluses.  

PubMed

Two orange-pigmented Gram-positive, aerobic bacteria were isolated from enrichment culture during degradation of brown alga Fucus evanescens thalluses. In this work, atomic force microscopy (AFM) has been used to study the cell morphology. The non-contact mode imaging revealed unusual irregular coccoid shape of cells, possessing a single flagellum. Bacteria produced carotenoid pigments, were chemo-organotrophic, alkaliphilic and halo-tolerant growing well on nutrient media containing up to 15% NaCl. Growth temperature ranged from 5 to 45 degrees C. The DNA base compositions were 48 mol% G + C and the level of DNA similarity of two strains was conspecific (98%). A comparative phylogenetic analysis of 16S rRNA gene sequences revealed that the strain KMM 3738 tightly clustered with recently described Planococcus maritimus (99.9% 16S rRNA gene sequence similarity). DNA-DNA hybridisation experiments revealed that DNA from the KMM 3738 showed 12-15% and 16-35% of genetic relatedness with the DNA of type strains of the genera Planomicrobium and Planococcus, respectively, and 87% with DNA from Planococcus maritimus, indicating that new isolates belong to the later species. PMID:17100323

Ivanova, E P; Wright, J P; Lysenko, A M; Zhukova, N V; Alexeeva, Y V; Buljan, V; Kalinovskaya, N I; Nicolau, D V; Christen, R; Mikhailov, V V

2006-01-01

53

Sortases and the Art of Anchoring Proteins to the Envelopes of Gram-Positive Bacteria  

PubMed Central

The cell wall envelopes of gram-positive bacteria represent a surface organelle that not only functions as a cytoskeletal element but also promotes interactions between bacteria and their environment. Cell wall peptidoglycan is covalently and noncovalently decorated with teichoic acids, polysaccharides, and proteins. The sum of these molecular decorations provides bacterial envelopes with species- and strain-specific properties that are ultimately responsible for bacterial virulence, interactions with host immune systems, and the development of disease symptoms or successful outcomes of infections. Surface proteins typically carry two topogenic sequences, i.e., N-terminal signal peptides and C-terminal sorting signals. Sortases catalyze a transpeptidation reaction by first cleaving a surface protein substrate at the cell wall sorting signal. The resulting acyl enzyme intermediates between sortases and their substrates are then resolved by the nucleophilic attack of amino groups, typically provided by the cell wall cross bridges of peptidoglycan precursors. The surface protein linked to peptidoglycan is then incorporated into the envelope and displayed on the microbial surface. This review focuses on the mechanisms of surface protein anchoring to the cell wall envelope by sortases and the role that these enzymes play in bacterial physiology and pathogenesis.

Marraffini, Luciano A.; DeDent, Andrea C.; Schneewind, Olaf

2006-01-01

54

Lipoteichoic acid preparations of gram-positive bacteria induce interleukin-12 through a CD14-dependent pathway.  

PubMed Central

Interleukin 12 (IL-12) strongly augments gamma interferon production by natural killer (NK) and T cells. IL-12 also promotes effective cell-mediated immune responses, which are particularly important against intracellular bacteria such as Listeria monocytogenes. While the lipopolysaccharide (LPS) of gram-negative bacteria induces monocyte production of IL-12, the relevant gram-positive components which induce IL-12 production are uncharacterized. We used the human monocytic cell line THP-1 to study IL-12 induction by gram-positive bacteria. Muramyl dipeptides as well as the major muramyl tetrapeptide component of Streptococcus pneumoniae were inactive for inducing IL-12. In contrast, lipoteichoic acid (LTA), a predominant surface glycolipid of gram-positive bacteria, potently induced IL-12 p40 gene expression. A competitive LPS antagonist, Rhodobacter sphaeroides LPS, inhibited LTA-induced IL-12 production, suggesting a common pathway for LPS and LTA in IL-12 activation. Pretreatment of cells with anti-CD14 monoclonal antibody blocked both LPS and LTA induction of IL-12 p40 expression. LTA also induced Thl development in naive CD4 T cells by an IL-12-dependent mechanism, indicating direct induction of physiologic levels of IL-12. Together, these results show that LTA is a potent surface structure of gram-positive bacteria which induces IL-12 in monocytes through a CD14-mediated pathway.

Cleveland, M G; Gorham, J D; Murphy, T L; Tuomanen, E; Murphy, K M

1996-01-01

55

Revised mechanism of D-alanine incorporation into cell wall polymers in Gram-positive bacteria.  

PubMed

Teichoic acids (TAs) are important for growth, biofilm formation, adhesion and virulence of Gram-positive bacterial pathogens. The chemical structures of the TAs vary between bacteria, though they typically consist of zwitterionic polymers that are anchored to either the peptidoglycan layer as in the case of wall teichoic acid (WTA) or the cell membrane and named lipoteichoic acid (LTA). The polymers are modified with D-alanines and a lack of this decoration leads to increased susceptibility to cationic antimicrobial peptides. Four proteins, DltA-D, are essential for the incorporation of d-alanines into cell wall polymers and it has been established that DltA transfers D-alanines in the cytoplasm of the cell onto the carrier protein DltC. However, two conflicting models have been proposed for the remainder of the mechanism. Using a cellular protein localization and membrane topology analysis, we show here that DltC does not traverse the membrane and that DltD is anchored to the outside of the cell. These data are in agreement with the originally proposed model for D-alanine incorporation through a process that has been proposed to proceed via a D-alanine undecaprenyl phosphate membrane intermediate. Furthermore, we found that WTA isolated from a Staphylococcus aureus strain lacking LTA contains only a small amount of D-alanine, indicating that LTA has a role, either direct or indirect, in the efficient D-alanine incorporation into WTA in living cells. PMID:23858088

Reichmann, Nathalie T; Cassona, Carolina Picarra; Gründling, Angelika

2013-09-01

56

Quinupristin-dalfopristin resistance among gram-positive bacteria in Taiwan.  

PubMed

To understand quinupristin-dalfopristin resistance among clinical isolates of gram-positive bacteria in Taiwan, where this agent is not yet available for clinical use, we evaluated 1,287 nonduplicate isolates recovered from January 1996 to December 1999 for in vitro susceptibility to quinupristin-dalfopristin and other newer antimicrobial agents. All methicillin-susceptible Staphylococcus aureus (MSSA) isolates were susceptible to quinupristin-dalfopristin. High rates of nonsusceptibility to quinupristin-dalfopristin (MICs, >/=2 microg/ml) were demonstrated for the following organisms: methicillin-resistant S. aureus (MRSA) (31%), coagulase-negative staphylococci (CoNS) (16%), Streptococcus pneumoniae (8%), viridans group streptococci (51%), vancomycin-susceptible enterococci (85%), vancomycin-resistant Enterococcus faecalis (100%), vancomycin-resistant Enterococcus faecium (66%), Leuconostoc spp. (100%), Lactobacillus spp. (50%), and Pediococcus spp. (87%). All isolates of MSSA, MRSA, S. pneumoniae, and viridans group streptococci were susceptible to vancomycin and teicoplanin. The rates of nonsusceptibility to vancomycin and teicoplanin were 5 and 7%, respectively, for CoNS, ranging from 12 and 18% for S. simulans to 0 and 0% for S. cohnii and S. auricularis. Moxifloxacin and trovafloxacin had good activities against these isolates except for ciprofloxacin-resistant vancomycin-resistant enterococci and methicillin-resistant staphylococci. In Taiwan, virginiamycin has been used in animal husbandry for more than 20 years, which may contribute to the high rates of quinupristin-dalfopristin resistance. PMID:11083643

Luh, K T; Hsueh, P R; Teng, L J; Pan, H J; Chen, Y C; Lu, J J; Wu, J J; Ho, S W

2000-12-01

57

Mechanistic antimicrobial approach of extracellularly synthesized silver nanoparticles against gram positive and gram negative bacteria.  

PubMed

The development of eco-friendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology. In this study, an extracellular enzyme system of a newly isolated microorganism, Exiguobacterium sp. KNU1, was used for the reduction of AgNO? solutions to silver nanoparticles (AgNPs). The extracellularly biosynthesized AgNPs were characterized by UV-vis spectroscopy, Fourier transform infra-red spectroscopy and transmission electron microscopy. The AgNPs were approximately 30 nm (range 5-50 nm) in size, well-dispersed and spherical. The AgNPs were evaluated for their antimicrobial effects on different gram negative and gram positive bacteria using the minimum inhibitory concentration method. Reasonable antimicrobial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was observed. The morphological changes occurred in all the microorganisms tested. In particular, E. coli exhibited DNA fragmentation after being treated with the AgNPs. Finally, the mechanism for their bactericidal activity was proposed according to the results of scanning electron microscopy and single cell gel electrophoresis. PMID:23867968

Tamboli, Dhawal P; Lee, Dae Sung

2013-09-15

58

Organization of genes for tetrapyrrole biosynthesis in gram--positive bacteria.  

PubMed

Clusters of genes encoding enzymes for tetrapyrrole biosynthesis were cloned from Bacillus sphaericus, Bacillus stearothermophilus, Brevibacillus brevis and Paenibacillus macerans. The sequences of all hemX genes found, and of a 6.3 kbp hem gene cluster from P. macerans, were determined. The structure of the hem gene clusters was compared to that of other Gram-positive bacteria. The Bacillus and Brevibacillus species have a conserved organization of the genes hemAXCDBL, required for biosynthesis of uroporphyrinogen III (UroIII) from glutamyl-tRNA. In P. macerans, the hem genes for UroIII synthesis are also closely linked but their organization is different: there is no hemX gene and the gene cluster also contains genes, cysG8 and cysG(A)-hemD, encoding the enzymes required for synthesis of sirohaem from UroIII. Bacillus subtilis contains genes for three proteins, NasF, YInD and YInF, with sequence similarity to Escherichia coli CysG, which is a multi-functional protein catalysing sirohaem synthesis from UroIII. It is shown that YInF is required for sirohaem synthesis and probably catalyses the precorrin-2 to sirohaem conversion. YInD probably catalyses precorrin-2 synthesis from UroIII and NasF seems to be specific for nitrite reduction. PMID:10217486

Johansson, P; Hederstedt, L

1999-03-01

59

[Isolation of Gram-positive bacteria from raw milk with antimicrobial residues].  

PubMed

Two hundred samples of raw milk were collected at the receiving plants located in three areas of high milk production in Zulia state, Venezuela. The CTT test and trial disk were used in order to detect the presence of antimicrobials. The positive samples were inoculated in tripticase soy broth, human blood agar and manitol salt agar in order to isolate Gram-positive bacteria. The identification of species was performed through biochemical tests. It was found that 45 samples (22.5%) of analyzed milk contained antimicrobials, and bacterial growth was obtained in 35 of them. 100 strains were isolated namely: 44 Staphylococcus, 19 Streptococcus, 17 Enterococcus, 9 Bacillus, 4 Micrococcus, 4 Corynebacterium and 3 Lactococcus. The most frequently isolated specie was S. aureus, the main producing agent of bovine mastitis in Zulia state, a microorganism frequently associated in the country to food-borne intoxications, associated to cheese processed from raw milk. It is recommended to apply control programs for the use of antibiotics. PMID:12214550

Faría Reyes, José; García Urdaneta, Aleida; Izquierdo Corser, Pedro; Allara Cagnasso, María; Valero Leal, Kutchynskaya

2002-03-01

60

Mannopeptimycins, a novel class of glycopeptide antibiotics active against gram-positive bacteria.  

PubMed

Mannopeptimycins alpha-epsilon, novel glycopeptides with activity against methicillin-resistant staphylococci and vancomycin-resistant enterococci, are purified from the fermentation broth of a strain of Streptomyces hygroscopicus, LL-AC98, and their structures characterized using spectroscopic analyses and chemical methods. The SAR data of the natural and synthetic esters demonstrate that the presence of hydrophobic groups near the terminal mannosyl moiety is critical for antibacterial potency. Scalable syntheses of 4,6-cyclic acetals and ketals on this moiety are used to produce significant quantities of the respective mannopeptimycin derivatives. These acetal and ketal derivatives exhibit potent activities against susceptible and resistant Gram-positive bacteria in both in vitro and in vivo experiments, comparable with or exceeding the activity of vancomycin. Studies on the mechanism of action suggest that the mannopeptimycins interfere with the late stages of bacterial cell wall biosynthesis. It is believed that these antibiotics inhibit the transglycosylation by binding to the transglycosylase substrate, lipid II. PMID:15702316

He, Haiyin

2005-06-01

61

Cultivation of aerobic chemoorganotrophic proteobacteria and gram-positive bacteria from a hot spring microbial mat.  

PubMed

The diversity of aerobic chemoorganotrophic bacteria inhabiting the Octopus Spring cyanobacterial mat community (Yellowstone National Park) was examined by using serial-dilution enrichment culture and a variety of enrichment conditions to cultivate the numerically significant microbial populations. The most abundant bacterial populations cultivated from dilutions to extinction were obtained from enrichment flasks which contained 9.0 x 10(2) primary producer (Synechococcus spp.) cells in the inoculum. Two isolates exhibited 16S rRNA nucleotide sequences typical of beta-proteobacteria. One of these isolates contained a 16S rRNA sequence identical to a sequence type previously observed in the mat by molecular retrieval techniques. Both are distantly related to a new sequence directly retrieved from the mat and contributed by a beta-proteobacterial community member. Phenotypically diverse gram-positive isolates genetically similar to Bacillus flavothermus were obtained from a variety of dilutions and enrichment types. These isolates exhibited identical 16S rRNA nucleotide sequences through a variable region of the molecule. Of the three unique sequences observed, only one had been previously retrieved from the mat, illustrating both the inability of the cultivation methods to describe the composition of a microbial community and the limitations of the ability of molecular retrieval techniques to describe populations which may be less abundant in microbial communities. PMID:8899976

Nold, S C; Kopczynski, E D; Ward, D M

1996-11-01

62

Combination of Pantothenamides with Vanin Inhibitors as a Novel Antibiotic Strategy against Gram-Positive Bacteria  

PubMed Central

The emergence of resistance against current antibiotics calls for the development of new compounds to treat infectious diseases. Synthetic pantothenamides are pantothenate analogs that possess broad-spectrum antibacterial activity in vitro in minimal media. Pantothenamides were shown to be substrates of the bacterial coenzyme A (CoA) biosynthetic pathway, causing cellular CoA depletion and interference with fatty acid synthesis. In spite of their potential use and selectivity for bacterial metabolic routes, these compounds have never made it to the clinic. In the present study, we show that pantothenamides are not active as antibiotics in the presence of serum, and we found that they were hydrolyzed by ubiquitous pantetheinases of the vanin family. To address this further, we synthesized a series of pantetheinase inhibitors based on a pantothenate scaffold that inhibited serum pantetheinase activity in the nanomolar range. Mass spectrometric analysis showed that addition of these pantetheinase inhibitors prevented hydrolysis of pantothenamides by serum. We found that combinations of these novel pantetheinase inhibitors and prototypic pantothenamides like N5-Pan and N7-Pan exerted antimicrobial activity in vitro, particularly against Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, and Streptococcus pyogenes) even in the presence of serum. These results indicate that pantothenamides, when protected against degradation by host pantetheinases, are potentially useful antimicrobial agents.

Jansen, Patrick A. M.; Hermkens, Pedro H. H.; Zeeuwen, Patrick L. J. M.; Botman, Peter N. M.; Blaauw, Richard H.; Burghout, Peter; van Galen, Peter M.; Mouton, Johan W.; Rutjes, Floris P. J. T.

2013-01-01

63

Dustborne and airborne Gram-positive and Gram-negative bacteria in high versus low ERMI homes.  

PubMed

The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified into low (<5) and high (>5) ERMI groups based on the average ERMI values as well as 2011 ERMI values. Dust and air samples were collected from the homes in 2011 and all samples were analyzed for Gram-positive and Gram-negative bacteria using QPCR assays, endotoxin by the LAL assay, and N-acetyl-muramic acid using HPLC. In addition, air samples were analyzed for culturable bacteria. When average ERMI values were considered, the concentration and load of Gram-positive bacteria determined with QPCR in house dust, but not air, were significantly greater in high ERMI homes than in low ERMI homes. Furthermore, the concentration of endotoxin, but not muramic acid, in the dust was significantly greater in high ERMI than in low ERMI homes. In contrast, when ERMI values of 2011 were considered, Gram-negative bacteria determined with QPCR in air, endotoxin in air, and muramic acid in dust were significantly greater in high ERMI homes. The results suggest that both short-term and long-term mold contamination in homes could be linked with the bacterial concentrations in house dust, however, only the current mold status was associated with bacterial concentrations in air. Although correlations were found between endotoxin and Gram-negative bacteria as well as between muramic acid and Gram-positive bacteria in the entire data set, diverging associations were observed between the different measures of bacteria and the home moldiness. It is likely that concentrations of cells obtained by QPCR and concentrations of cell wall components are not equivalent and represent too broad categories to understand the bacterial composition and sources of the home microbiota. PMID:24642096

Adhikari, Atin; Kettleson, Eric M; Vesper, Stephen; Kumar, Sudhir; Popham, David L; Schaffer, Christopher; Indugula, Reshmi; Chatterjee, Kanistha; Allam, Karteek K; Grinshpun, Sergey A; Reponen, Tiina

2014-06-01

64

Meso-substituted cationic porphyrins as efficient photosensitizers of gram-positive and gram-negative bacteria  

Microsoft Academic Search

Previous studies on the photosensitization of bacterial cells with different neutral or negatively charged porphyrins and phthalocyanines have demonstrated that, although Gram-positive bacteria are efficiently photoinactivated, Gram-negatrive bacteria become photosensitive only after modification of the permeability of their outer membrane.The results described in this paper show that two meso-substituted cationic porphyrins, namely tetra(4N-methyl-pyridyl) porphine tetraiodide and the tetra(4N,N,N,-trimethyl-anilinium) porphine, efficiently

Michèle Merchat; Giulio Bertolini; Paolo Giacomini; Angeles Villaneuva; Giulio Jori

1996-01-01

65

Coexistence of CD14Dependent and Independent Pathways for Stimulation of Human Monocytes by Gram-Positive Bacteria  

Microsoft Academic Search

The cell wall is a key inflammatory agent of gram-positive bacteria. Possible receptors mediating cell wall-induced inflammation include CD14 and platelet-activating factor (PAF) receptor. To delineate the conditions under which these various receptors might be used, human monocytic THP-1 cells and heparinized whole human blood were stimulated with lipopolysaccharide (LPS), intact Streptococcus pneumoniae bacteria, or purified pneumococcal cell wall. THP-1

ANJE CAUWELS; ELAINE WAN; MICHAELA LEISMANN; ELAINE TUOMANEN

1997-01-01

66

Com parative genomics of the methionine metabolism in Gram-positive bacteria: a variety of regulatory systems  

Microsoft Academic Search

Regulation of the methionine biosynthesis and trans- port genes in bacteria is rather diverse and involves two RNA-level regulatory systems and at least three DNA-level systems. In particular, the methionine metabolism in Gram-positive bacteria was known to be controlled by the S-box and T-box mechanisms, both acting on the level of premature termination of transcription. Using comparative analysis of genes,

Dmitry A. Rodionov; Alexey G. Vitreschak; Andrey A. Mironov; Mikhail S. Gelfand

67

Speciation of Gram-positive bacteria in fresh and ambient-stored sub-tropical marine fish.  

PubMed

This study identified Gram-positive bacteria in three sub-tropical marine fish species; Pseudocaranx dentex (silver trevally), Pagrus auratus (snapper) and Mugil cephalus (sea mullet). It further elucidated the role played by fish habitat, fish body part and ambient storage on the composition of the Gram-positive bacteria. A total of 266 isolates of Gram-positive bacteria were identified by conventional biochemical methods, VITEK, PCR using genus- and species-specific primers and/or 16S rRNA gene sequencing. The isolates were found to fall into 13 genera and 30 species. In fresh fish, Staphylococcus epidermidis and Micrococcus luteus were the most frequent isolates. After ambient storage, S. epidermidis, S. xylosus and Bacillus megaterium were no longer present whereas S. warneri, B. sphaericus, Brevibacillus borstelensis, Enterococcus faecium and Streptococcus uberis increased in frequency. Micrococcus luteus and S. warneri were the most prevalent isolates from P. dentex, while E. faecium and Strep. uberis were the most frequent isolates from P. auratus and M. cephalus. With respect to different parts of the fish body, E. faecium, Strep. uberis and B. sphaericus were the most frequent isolates from the muscles, E. faecium, Strep. uberis from the gills and M. luteus from the gut. This study showed a diversity of Gram-positive bacteria in sub-tropical marine fish; however, their abundance was affected by fish habitat, fish body part and ambient storage. PMID:20110133

Al Bulushi, Ismail M; Poole, Susan E; Barlow, Robert; Deeth, Hilton C; Dykes, Gary A

2010-03-31

68

Dustborne and airborne gram-positive and gram-negative bacteria in high versus low ERMI homes  

EPA Science Inventory

The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified...

69

Photoinactivation of bacteria. Use of a cationic water-soluble zinc phthalocyanine to photoinactivate both Gram-negative and Gram-positive bacteria  

Microsoft Academic Search

The photosensitization of microorganisms is potentially useful for sterilization and for the treatment of certain bacterial diseases. Unit now, any broad spectrum approach has been inhibited because, although Gram-positive bacteria can be photoinactivated by a range of photosensitizer, Gram-negative bacteria have not usually been susceptible to photosensitized destruction.In the present work, it has been shown that the Gram-negative bacteria Escheria

Andrew Minnock; David I. Vernon; Jack Schofield; John Griffiths; J. Howard Parish; Stanley B. Brown

1996-01-01

70

Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L.) on Two Gram-Negative and Gram-Positive Bacteria  

PubMed Central

Aim. To determine the antimicrobial potential of guava (Psidium guajava) leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water). The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50??L leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3?mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0?mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties.

Biswas, Bipul; Rogers, Kimberly; McLaughlin, Fredrick; Yadav, Anand

2013-01-01

71

Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L.) on Two Gram-Negative and Gram-Positive Bacteria.  

PubMed

Aim. To determine the antimicrobial potential of guava (Psidium guajava) leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water). The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50? ? L leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3?mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0?mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties. PMID:24223039

Biswas, Bipul; Rogers, Kimberly; McLaughlin, Fredrick; Daniels, Dwayne; Yadav, Anand

2013-01-01

72

Genetic determinants of antimicrobial resistance in Gram positive bacteria from organic foods.  

PubMed

Bacterial biocide resistance is becoming a matter of concern. In the present study, a collection of biocide-resistant, Gram-positive bacteria from organic foods (including 11 isolates from genus Bacillus, 25 from Enterococcus and 10 from Staphylococcus) were analyzed for genes associated to biocide resistance efflux pumps and antibiotic resistance. The only qac-genes detected were qacA/B (one Bacillus cereus isolate) and smr (one B. cereus and two Staphylococcus saprophyticus isolates). Efflux pump genes efrA and efrB genes were detected in Staphylococcus (60% of isolates), Bacillus (54.54%) and Enterococcus (24%); sugE was detected in Enterococcus (20%) and in one Bacillus licheniformis; mepA was detected in Staphylococcus (60%) and in one Enterococcus isolate (which also carried mdeA), and norE gene was detected only in one Enterococcus faecium and one S. saprophyticus isolate. An amplicon for acrB efflux pump was detected in all but one isolate. When minimal inhibitory concentrations (MICs) were determined, it was found that the addition of reserpine reduced the MICs by eight fold for most of the biocides and isolates, corroborating the role of efflux pumps in biocide resistance. Erythromycin resistance gene ermB was detected in 90% of Bacillus isolates, and in one Staphylococcus, while ereA was detected only in one Bacillus and one Staphyloccus, and ereB only in one Staphylococcus. The ATP-dependent msrA gene (which confers resistance to macrolides, lincosamides and type B streptogramins) was detected in 60% of Bacillus isolates and in all staphylococci, which in addition carried msrB. The lincosamide and streptogramin A resistance gene lsa was detected in Staphylococcus (40%), Bacillus (27.27%) and Enterococcus (8%) isolates. The aminoglycoside resistance determinant aph (3_)-IIIa was detected in Staphylococcus (40%) and Bacillus (one isolate), aph(2_)-1d in Bacillus (27.27%) and Enterococcus (8%), aph(2_)-Ib in Bacillus (one isolate), and the bifunctional aac(6_)1e-aph(2_)-Ia in Staphylococcus (20%), Enterococcus (8%) and Bacillus (one isolate). Chloramphenicol resistance cat gene was detected in Enterococcus (8%) and Staphylococcus (20%), and blaZ only in Staphylococcus (20%). All other antibiotic or biocide resistance genes investigated were not detected in any isolate. Isolates carrying multiple biocide and antibiotic determinants were frequent among Bacillus (36.36%) and Staphylococcus (50%), but not Enterococcus. These results suggest that biocide and antibiotic determinants may be co-selected. PMID:24361832

Fernández-Fuentes, Miguel Angel; Abriouel, Hikmate; Ortega Morente, Elena; Pérez Pulido, Rubén; Gálvez, Antonio

2014-02-17

73

Intersection of the stringent response and the CodY regulon in low GC Gram-positive bacteria.  

PubMed

Bacteria adapt efficiently to a wide range of nutritional environments. Therefore, they possess overlapping regulatory systems that detect intracellular pools of key metabolites. In low GC Gram-positive bacteria, two global regulators, the stringent response and the CodY repressor, respond to an intracellular decrease in amino acid content. Amino acid limitation leads to rapid synthesis of the alarmones pppGpp and ppGpp through the stringent response and inactivates the CodY repressor. Two cofactors, branched chain amino acids (BCAA) and GTP, are ligands for CodY and facilitate binding to the target DNA. Because (p)ppGpp synthesis and accumulation evidentially reduce the intracellular GTP pool, CodY is released from the DNA, and transcription of target genes is altered. Here, we focus on this intimate link between the stringent response and CodY regulation in different Gram-positive species. PMID:24462007

Geiger, Tobias; Wolz, Christiane

2014-03-01

74

Identification of lactic acid bacteria and Gram-positive catalase-positive cocci isolated from naturally fermented sausage (sucuk).  

PubMed

The aim of the study was to identify lactic acid bacteria and Gram-positive catalase-positive cocci isolated from Turkish dry fermented sausage (sucuk) produced by 7 different manufacturers without using starter culture. A total of 129 isolates of lactic acid bacteria were identified phenotypically. Lactobacillus plantarum was the dominant species (45.7%) followed by L. curvatus (10.9%) and L. fermentum (9.3%). Pediococcus isolates were identified as P. pentosaceus and P. acidilactici. All the isolates of gram-positive and catalase-positive cocci (123 isolates) were classified as Staphylococcus except for 1 isolate assigned to Kocuria rosea. The species isolated most often were S. xylosus (41.5%) and S. saprophyticus (28.5%). Four isolates were identified as S. equorum (3.3%), 1 isolate was assigned to S. carnosus (0.8%). PMID:19019118

Kaban, G; Kaya, M

2008-10-01

75

In Vitro Activity of Ozenoxacin against Quinolone-Susceptible and Quinolone-Resistant Gram-Positive Bacteria  

PubMed Central

In vitro activity of ozenoxacin, a novel nonfluorinated topical (L. D. Saravolatz and J. Leggett, Clin. Infect. Dis. 37:1210–1215, 2003) quinolone, was compared with the activities of other quinolones against well-characterized quinolone-susceptible and quinolone-resistant Gram-positive bacteria. Ozenoxacin was 3-fold to 321-fold more active than other quinolones. Ozenoxacin could represent a first-in-class nonfluorinated quinolone for the topical treatment of a broad range of dermatological infections.

Lopez, Y.; Tato, M.; Espinal, P.; Garcia-Alonso, F.; Gargallo-Viola, D.; Canton, R.

2013-01-01

76

Comparison of the D-Glutamate-Adding Enzymes from Selected Gram-Positive and Gram-Negative Bacteria  

Microsoft Academic Search

The biochemical properties of the D-glutamate-adding enzymes (MurD) from Escherichia coli, Haemophilus influenzae, Enterococcus faecalis, and Staphylococcus aureus were investigated to detect any differences in the activity of this enzyme between gram-positive and gram-negative bacteria. The genes (murD) that encode these enzymes were cloned into pMAL-c2 fusion vector and overexpressed as maltose-binding protein-MurD fusion proteins. Each fusion protein was purified

ANN W. WALSH; PAUL J. FALK; JANE THANASSI; LINDA DISCOTTO; MICHAEL J. PUCCI; HSU-TSO HO

1999-01-01

77

Improved Pattern for Genome-Based Screening Identifies Novel Cell Wall-Attached Proteins in Gram-Positive Bacteria  

Microsoft Academic Search

With a large number of sequenced microbial genomes available, tools for identifying groups or classes of proteins have become increasingly important. Here we present an improved pattern for the identification of cell wall-attached proteins (CWPs), a group of proteins with diverse and important functions in gram-positive bacteria. This tripartite pattern is based on analysis of 65 previously described cell wall-attached

ROBERT JANULCZYK; MAGNUS RASMUSSEN

2001-01-01

78

Secretory phospholipase A2 in dromedary tears: a host defense against staphylococci and other gram-positive bacteria.  

PubMed

The best known physiologic function of secreted phospholipase A2 (sPLA2) group IIA (sPLA2-IIA) is defense against bacterial infection through hydrolytic degradation of bacterial membrane phospholipids. In fact, sPLA2-IIA effectively kills Gram-positive bacteria and to a lesser extent Gram-negative bacteria and is considered a major component of the eye's innate immune defense system. The antibacterial properties of sPLA2 have been demonstrated in rabbit and human tears. In this report, we have analyzed the bactericidal activity of dromedary tears and the subsequently purified sPLA2 on several Gram-positive bacteria. Our results showed that the sPLA2 displays a potent bactericidal activity against all the tested bacteria particularly against the Staphylococcus strains when tested in the ionic environment of tears. There is a synergic action of the sPLA2 with lysozyme when added to the bacteria culture prior to sPLA2. Interestingly, lysozyme purified from dromedary tears showed a significant bactericidal activity against Listeria monocytogene and Staphylococcus epidermidis, whereas the one purified from human tears displayed no activity against these two strains. We have also demonstrated that Ca(2+) is crucial for the activity of dromedary tear sPLA2 and to a less extent Mg(2+) ions. Given the presence of sPLA2 in tears and intestinal secretions, this enzyme may play a substantial role in innate mucosal and systemic bactericidal defenses against Gram-positive bacteria. PMID:23344945

Ben Bacha, Abir; Abid, Islem

2013-03-01

79

Discriminatory antibacterial effects of calix[n]arene capped silver nanoparticles with regard to gram positive and gram negative bacteria.  

PubMed

Silver nanoparticles capped with nine different sulphonated calix[n]arenes were tested for their anti-bacterial effects against B. subtilis and E. coli at an apparent concentration of 100 nM in calix[n]arene. The results show the para-sulphonato-calix[n]arenes are active against Gram positive bacteria and the derivatives having sulphonate groups at both para and alkyl terminal positions are active against Gram negative bacteria. The calix[6]arene derivative with only O-alkyl sulphonate groups shows bactericidal activity. PMID:23831853

Boudebbouze, Samira; Coleman, Anthony W; Tauran, Yannick; Mkaouar, Hela; Perret, Florent; Garnier, Alexandrine; Brioude, Arnaud; Kim, Beomjoon; Maguin, Emmanuelle; Rhimi, Moez

2013-08-18

80

Competitive adsorption of metal cations onto two gram positive bacteria: testing the chemical equilibrium model  

Microsoft Academic Search

In order to test the ability of a surface complexation approach to account for metal-bacteria interactions in near surface fluid-rock systems, we have conducted experiments that measure the extent of adsorption in mixed metal, mixed bacteria systems. This study tests the surface complexation approach by comparing estimated extents of adsorption based on surface complexation modeling to those we observed in

David A. Fowle; Jeremy B. Fein

1999-01-01

81

Synthesis and in vitro evaluation of substituted phenyl-piperazinyl-phenyl oxazolidinones against Gram-positive bacteria.  

PubMed

With the incidence of linezolid-resistant Enterococcus faecalis, E. faecium and Staphylococcus aureus, modification of linezolid at the 5- and/or 3-positions led to the development of a series of 3-(methoxyl-phenyl)-piperazinyl-phenyl oxazolidinone analogues. These compounds were tested in vitro against six gram-positive standard organisms (S. aureus, S. epidermidis, S. pneumoniae, S. albus, Streptococcus enteridis and S. nonhemolyticus). 5-acetylaminomethyl oxazolidinones bearing fluorine at 3'-position of phenyl ring showed activities against several gram-positive bacteria (MIC: 3.13-6.25 mug/mL). The position of methoxyl group on the phenyl ring of piperazine group affected antibacterial spectrum. 3-(4'- (para-methoxyl-phenyl)-piperazinyl)-(3'-fluoro)-phenyl-5-acetylaminomethyl oxazolidinone was found active against 5 gram-positive organisms except S. nonhemolyticus, whereas 3-(4'-(ortho-methoxyl-phenyl)-piperazinyl)-(3'-fluoro)-phenyl-5-acetylaminomethyl oxazolidinone was found active only against 2 gram-positive organisms, namely S. albus, S. enteridis. PMID:17461974

Liu, Jidong; He, Baoyuan; Yu, Aizhen; Zhou, Weicheng

2007-04-01

82

Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study  

PubMed Central

Background Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe2O3 nanoparticles against Gram-positive and Gram-negative bacteria. Methods and results Nanosized particles of three metal oxides (ZnO, CuO, and Fe2O3) were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe2O3, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Conclusion Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe2O3 nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe2O3.

Azam, Ameer; Ahmed, Arham S; Oves, Mohammad; Khan, Mohammad S; Habib, Sami S; Memic, Adnan

2012-01-01

83

Functionalized magnetic iron oxide (Fe3O4) nanoparticles for capturing gram-positive and gram-negative bacteria.  

PubMed

The development of nanotechnology in biology and medicine has raised the need for conjugation of nanoparticles (NPs) to biomolecules. In this study, magnetic and functionalized magnetic iron oxide nanoparticles were synthesized and used as affinity probes to capture Gram-positive/negative bacteria. The morphology and properties of the magnetic NPs were examined by transmission electron microscopy, Fourier transform infrared spectroscopy, and zeta potential measurements. Furthermore, this study investigated the interaction between functionalized magnetic nanoparticles and Gram positive/negative bacteria. The positively and negatively charged magnetic nanoparticles include functionalities of Fe3O4, SiO2, TiO2, ZrO2, poly ethyleneimine (PEI) and poly acrylic acid. Their capture efficiencies for bacteria were investigated based on factors such as zeta potential, concentration and pH value. PEI particles carry a positive charge over a range of pH values from 3 to 10, and the particles were found to be an excellent candidate for capturing bacteria over such pH range. Since the binding force is mainly electrostatic, the architecture and orientation of the functional groups on the NP surface are not critical. Finally the captured bacteria were analyzed using matrix-assisted laser desorption/ionization mass spectrometry. The minimum detection limit was 10(4) CFU/mL and the analysis time was reduced to be less than 1 hour. In addition, the detection limit could be reduced to an extremely low concentration of 50 CFU/mL when captured bacteria were cultivated. PMID:25016643

Reddy, P Muralidhar; Chang, Kai-Chih; Liu, Zhen-Jun; Chen, Cheng-Tung; Ho, Yen-Peng

2014-08-01

84

Molecular modeling of Gram-positive bacteria peptidoglycan layer, selected glycopeptide antibiotics and vancomycin derivatives modified with sugar moieties.  

PubMed

Proper understanding of the mechanisms of binding to Gram-positive bacteria cell wall layers-especially to the peptidoglycan (PG) layer, seems to be crucial for proper development of new drug candidates which are effective against these bacteria. In this work we have constructed two different models of the Gram-positive bacteria PG layer: the layered and the scaffold models. PG conformational changes during geometry optimization, models relaxation, and molecular dynamics were described and discussed. We have found that the border surface of both PG layer models differs from the surface located away from the edge of models and the chains formed by disaccharide units prefer helix-like conformation. This curling of PG chains significantly affects the shape of antibiotic-accessible surface and the process is thus crucial for new drug development. Glycopeptide antibiotics effective against Gram-positive bacteria, such as vancomycin and its semisynthetic derivatives-oritavancin and telavancin, bind to d-alanyl-d-alanine stem termini on the peptidoglycan precursors of the cell wall. This binding inhibits cross-linking between the peptides and subsequently prevents cell wall synthesis. In this study some of the aspects of conformational freedom of vancomycin and restrictions from the modifications of vancomycin structure introduced into oritavancin and telavancin and five other vancomycin derivatives (with addition of 2-acetamido-2-deoxy-?-d-galactopyranosylamine, 2-acetamido-2-deoxy-?-d-glucopyranosylamine, 1-amine-1-deoxy-d-glucitol, 2-amino-2-deoxy-d-galactitol, or 2-amino-2-deoxy-d-glucitol to the C-terminal amino acid group in the vancomycin) are presented and discussed. The resulting molecular dynamics trajectories, root mean square deviation changes of aglycon and saccharide moieties as well as a comparative study of possible interactions with cyclic and chain forms of modified groups have been carried out, measured, and analyzed. Energetically advantageous conformations show close similarity to the structures known from the experimental data, but the diversity of others suggest very high conformational freedom of all modeled antibiotics and vancomycin derivatives. Alditol derivatives move closer to the peptidoglycan chain more easily but they also form intramolecular interactions more frequently than their homologous cyclic forms. One of the proposed derivatives seems to be a promising agent which is efficient in treatment of infections caused by Gram-positive bacteria. PMID:24685455

Slusarz, Rafa?; Szulc, Monika; Madaj, Janusz

2014-05-01

85

Modeling of rare earth element sorption to the Gram positive Bacillus subtilis bacteria surface.  

PubMed

In this study, rare earth element (REE) binding constants and site concentration on the Gram+ bacteria surfaces were quantified using a multi-site Langmuir isotherm model, along with a linear programming regression method (LPM), applied to fit experimental REE sorption data. This approach found one discrete REE binding site on the Gram+ Bacillus subtilis surface for the pH range of 2.5-4.5. Average log10 REE binding constants for a site j on these bacteria ranged from 1.08±0.04 to 1.40±0.04 for the light REE (LREE: La to Eu), and from 1.36±0.03 to 2.18±0.14 for the heavy REE (HREE: Gd to Lu) at the highest biomass concentration of 1.3 g/L of B. subtilis bacteria. Similar values were obtained for bacteria concentrations of 0.39 and 0.67 g/L indicating the independence of REE sorption constants on biomass concentration. Within the experimental pH range in this study, B. subtilis was shown to have a lower affinity for LREE (e.g. La, Ce, Pr, Nd) and a higher affinity for HREE (e.g. Tm, Yb, Lu) suggesting an enrichment of HREE on the surface of Gram+ bacteria. Total surface binding site concentrations of 6.73±0.06 to 5.67±0.06 and 5.53±0.07 to 4.54±0.03 mol/g of bacteria were observed for LREE and HREE respectively, with the exception of Y, which showed a total site concentration of 9.53±0.03, and a log K(REE,j) of 1.46±0.02 for a biomass content of 1.3 g/L. The difference in these values (e.g. a lower affinity and increased binding site concentration for LREE, and the contrary for the HREE) suggests a distinction between the LREE and HREE binding modes to the Gram+ bacteria reactive surface at low pH. This further implies that HREE may bind more than one monoprotic reactive group on the cell surface. A multisite Langmuir isotherm approach along with the LPM regression method, not requiring prior knowledge of the number or concentration of cell surface REE complexation sites, were able to distinguish between the sorption constant and binding site concentration patterns of LREE and HREE on the Gram+ B. subtilis surface. This approach quantified the enrichment of Tm, Yb and Lu on the bacteria surface and it has therefore proven to be a useful tool for the study of natural reactive sorbent materials controlling REE partitioning in the natural environment. PMID:24183437

Martinez, Raul E; Pourret, Olivier; Takahashi, Yoshio

2014-01-01

86

Comparison of the d-Glutamate-Adding Enzymes from Selected Gram-Positive and Gram-Negative Bacteria  

PubMed Central

The biochemical properties of the d-glutamate-adding enzymes (MurD) from Escherichia coli, Haemophilus influenzae, Enterococcus faecalis, and Staphylococcus aureus were investigated to detect any differences in the activity of this enzyme between gram-positive and gram-negative bacteria. The genes (murD) that encode these enzymes were cloned into pMAL-c2 fusion vector and overexpressed as maltose-binding protein–MurD fusion proteins. Each fusion protein was purified to homogeneity by affinity to amylose resin. Proteolytic treatments of the fusion proteins with factor Xa regenerated the individual MurD proteins. It was found that these fusion proteins retain d-glutamate-adding activity and have Km and Vmax values similar to those of the regenerated MurDs, except for the H. influenzae enzyme. Substrate inhibition by UDP-N-acetylmuramyl-l-alanine, the acceptor substrate, was observed at concentrations greater than 15 and 30 ?M for E. coli and H. influenzae MurD, respectively. Such substrate inhibition was not observed with the E. faecalis and S. aureus enzymes, up to a substrate concentration of 1 to 2 mM. In addition, the two MurDs of gram-negative origin were shown to require monocations such as NH4+ and/or K+, but not Na+, for optimal activity, while anions such as Cl? and SO42? had no effect on the enzyme activities. The activities of the two MurDs of gram-positive origin, on the other hand, were not affected by any of the ions tested. All four enzymes required Mg2+ for the ligase activity and exhibited optimal activities around pH 8. These differences observed between the gram-positive and gram-negative MurDs indicated that the two gram-negative bacteria may apply a more stringent regulation of cell wall biosynthesis at the early stage of peptidoglycan biosynthesis pathway than do the two gram-positive bacteria. Therefore, the MurD-catalyzed reaction may constitute a fine-tuning step necessary for the gram-negative bacteria to optimally maintain its relatively thin yet essential cell wall structure during all stages of growth.

Walsh, Ann W.; Falk, Paul J.; Thanassi, Jane; Discotto, Linda; Pucci, Michael J.; Ho, Hsu-Tso

1999-01-01

87

Surface multiheme c-type cytochromes from Thermincola potens: Implications for dissimilatory metal reduction by Gram-positive bacteria  

NASA Astrophysics Data System (ADS)

Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they have been shown to be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or the humic substances analog, anthraquinone-2,6-disulfonate (AQDS). The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS and that several MHCs are localized to the cell wall or cell surface of T. potens. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results are the first direct evidence for cell-wall associated cytochromes and MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium.

Carlson, H. K.; Iavarone, A. T.; Gorur, A.; Yeo, B. S.; Tran, R.; Melnyk, R. A.; Mathies, R. A.; Auer, M.; Coates, J. D.

2011-12-01

88

Surface multiheme c-type cytochromes from Thermincola potens and implications for respiratory metal reduction by Gram-positive bacteria  

PubMed Central

Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they may be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or anthraquinone-2,6-disulfonate (AQDS), an analog of the redox active components of humic substances. The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin-shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS, and that several MHCs are localized to the cell wall or cell surface. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants, suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results provide unique direct evidence for cell wall-associated cytochromes and support MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium.

Carlson, Hans K.; Iavarone, Anthony T.; Gorur, Amita; Yeo, Boon Siang; Tran, Rosalie; Melnyk, Ryan A.; Mathies, Richard A.; Auer, Manfred; Coates, John D.

2012-01-01

89

Gram-Positive Bacteria as Host Cells for Heterologous Production of Biopharmaceuticals  

Microsoft Academic Search

The increasing demand of recombinant compounds in bioscience and bioindustries requires the further exploration and improvement\\u000a of production systems including bacteria, fungi, insect and human cells. For compounds that do not require glycosylation for\\u000a biological activity, microbial systems are most favourable hosts because of high level expression and relatively inexpensive\\u000a culture systems. Traditionally, Escherichia coli was and still is most

LIEVE VAN MELLAERT; Jozef Anné

90

Competitive adsorption of metal cations onto two gram positive bacteria: testing the chemical equilibrium model  

NASA Astrophysics Data System (ADS)

In order to test the ability of a surface complexation approach to account for metal-bacteria interactions in near surface fluid-rock systems, we have conducted experiments that measure the extent of adsorption in mixed metal, mixed bacteria systems. This study tests the surface complexation approach by comparing estimated extents of adsorption based on surface complexation modeling to those we observed in the experimental systems. The batch adsorption experiments involved Ca, Cd, Cu, and Pb adsorption onto the surfaces of 2 g positive bacteria: Bacillus subtilis and Bacillus licheniformis. Three types of experiments were performed: 1. Single metal (Ca, Cu, Pb) adsorption onto a mixture of B. licheniformis and B. subtilis; 2. mixed metal (Cd, Cu, and Pb; Ca and Cd) adsorption onto either B. subtilis or B. licheniformis; and 3. mixed or single metal adsorption onto B. subtilis and B. licheniformis. %Independent of the experimental results, and based on the site specific stability constants for Ca, Cd, Cu, and Pb interactions with the carboxyl and phosphate sites on B. licheniformis and B. subtilis determined by Fein et al. (1997), by Daughney et al. (1998) and in this study, we estimate the extent of adsorption that is expected in the above experimental systems. Competitive cation adsorption experiments in both single and double bacteria systems exhibit little adsorption at pH values less than 4. With increasing pH above 4.0, the extent of Ca, Cu, Pb and Cd adsorption also increases due to the increased deprotonation of bacterial surface functional groups. In all cases studied, the estimated adsorption behavior is in excellent agreement with the observations, with only slight differences that were within the uncertainties of the estimation and experimental procedures. Therefore, the results indicate that the use of chemical equilibrium modeling of aqueous metal adsorption onto bacterial surfaces yields accurate predictions of the distribution of metals in complex multicomponent systems.

Fowle, David A.; Fein, Jeremy B.

1999-10-01

91

REPORT ANTIBACTERIAL ACTIVITY OF OREGANO (ORIGANUM VULGARE LINN.) AGAINST GRAM POSITIVE BACTERIA  

Microsoft Academic Search

The present investigation is focused on antibacterial potential of infusion, decoction and essential oil of oregano (Origanum vulgare) against 111 Gram-positive bacterial isolates belonging to 23 different species related to 3 genera. Infusion and essential oil exhibited antibacterial activity against Staphylococcus saprophyticus, S. aureus, Micrococcus roseus, M. kristinae, M. nishinomiyaensis, M. lylae, M. luteus, M. sedentarius, M. varians, Bacillus megaterium,

SABAHAT SAEED; PERWEEN TARIQ

92

Plants used in Guatemala for the treatment of respiratory diseases. 1. Screening of 68 plants against gram-positive bacteria.  

PubMed

Respiratory ailments are important causes of morbidity and mortality in developing countries. Ethnobotanical surveys and literature reviews conducted in Guatemala during 1986-88 showed that 234 plants from 75 families, most of them of American origin, have been used for the treatment of respiratory ailments. Three Gram-positive bacteria causing respiratory infections (Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes) were used to screen 68 of the most commonly used plants for activity. Twenty-eight of these (41.2%) inhibited the growth of one or more of the bacteria tested. Staphylococcus aureus was inhibited by 18 of the plant extracts, while 7 extracts were effective against Streptococcus pyogenes. Plants of American origin which exhibited antibacterial activity were: Gnaphalium viscosum, Lippia alba, Lippia dulcis, Physalis philadelphica, Satureja brownei, Solanum nigrescens and Tagetes lucida. These preliminary in vitro results provide scientific basis for the use of these plants against bacterial respiratory infections. PMID:2023428

Caceres, A; Alvarez, A V; Ovando, A E; Samayoa, B E

1991-02-01

93

A super-family of transcriptional activators regulates bacteriophage packaging and lysis in Gram-positive bacteria  

PubMed Central

The propagation of bacteriophages and other mobile genetic elements requires exploitation of the phage mechanisms involved in virion assembly and DNA packaging. Here, we identified and characterized four different families of phage-encoded proteins that function as activators required for transcription of the late operons (morphogenetic and lysis genes) in a large group of phages infecting Gram-positive bacteria. These regulators constitute a super-family of proteins, here named late transcriptional regulators (Ltr), which share common structural, biochemical and functional characteristics and are unique to this group of phages. They are all small basic proteins, encoded by genes present at the end of the early gene cluster in their respective phage genomes and expressed under cI repressor control. To control expression of the late operon, the Ltr proteins bind to a DNA repeat region situated upstream of the terS gene, activating its transcription. This involves the C-terminal part of the Ltr proteins, which control specificity for the DNA repeat region. Finally, we show that the Ltr proteins are the only phage-encoded proteins required for the activation of the packaging and lysis modules. In summary, we provide evidence that phage packaging and lysis is a conserved mechanism in Siphoviridae infecting a wide variety of Gram-positive bacteria.

Quiles-Puchalt, Nuria; Tormo-Mas, Maria Angeles; Campoy, Susana; Toledo-Arana, Alejandro; Monedero, Vicente; Lasa, Inigo; Novick, Richard P.; Christie, Gail E.; Penades, Jose R.

2013-01-01

94

A super-family of transcriptional activators regulates bacteriophage packaging and lysis in Gram-positive bacteria.  

PubMed

The propagation of bacteriophages and other mobile genetic elements requires exploitation of the phage mechanisms involved in virion assembly and DNA packaging. Here, we identified and characterized four different families of phage-encoded proteins that function as activators required for transcription of the late operons (morphogenetic and lysis genes) in a large group of phages infecting Gram-positive bacteria. These regulators constitute a super-family of proteins, here named late transcriptional regulators (Ltr), which share common structural, biochemical and functional characteristics and are unique to this group of phages. They are all small basic proteins, encoded by genes present at the end of the early gene cluster in their respective phage genomes and expressed under cI repressor control. To control expression of the late operon, the Ltr proteins bind to a DNA repeat region situated upstream of the terS gene, activating its transcription. This involves the C-terminal part of the Ltr proteins, which control specificity for the DNA repeat region. Finally, we show that the Ltr proteins are the only phage-encoded proteins required for the activation of the packaging and lysis modules. In summary, we provide evidence that phage packaging and lysis is a conserved mechanism in Siphoviridae infecting a wide variety of Gram-positive bacteria. PMID:23771138

Quiles-Puchalt, Nuria; Tormo-Más, María Ángeles; Campoy, Susana; Toledo-Arana, Alejandro; Monedero, Vicente; Lasa, Iñigo; Novick, Richard P; Christie, Gail E; Penadés, José R

2013-08-01

95

Desulfotomaculum spp. and related gram-positive sulfate-reducing bacteria in deep subsurface environments  

PubMed Central

Gram-positive spore-forming sulfate reducers and particularly members of the genus Desulfotomaculum are commonly found in the subsurface biosphere by culture based and molecular approaches. Due to their metabolic versatility and their ability to persist as endospores. Desulfotomaculum spp. are well-adapted for colonizing environments through a slow sedimentation process. Because of their ability to grow autotrophically (H2/CO2) and produce sulfide or acetate, these microorganisms may play key roles in deep lithoautotrophic microbial communities. Available data about Desulfotomaculum spp. and related species from studies carried out from deep freshwater lakes, marine sediments, oligotrophic and organic rich deep geological settings are discussed in this review.

Aullo, Thomas; Ranchou-Peyruse, Anthony; Ollivier, Bernard; Magot, Michel

2013-01-01

96

Anaerobic naphthalene degradation by Gram-positive, iron-reducing bacteria.  

PubMed

An anaerobic naphthalene-degrading culture (N49) was enriched with ferric iron as electron acceptor. A closed electron balance indicated the total oxidation of naphthalene to CO(2). In all growing cultures, the concentration of the presumed central metabolite of naphthalene degradation, 2-naphthoic acid, increased concomitantly with growth. The first metabolite of anaerobic methylnaphthalene degradation, naphthyl-2-methyl-succinic acid, was not identified in culture supernatants, which does not support a methylation to methylnaphthalene as the initial activation reaction of naphthalene, but rather a carboxylation, as proposed for other naphthalene-degrading cultures. Substrate utilization tests revealed that the culture was able to grow on 1-methyl-naphthalene, 2-methyl-naphthalene, 1-naphthoic acid or 2-naphthoic acid, whereas it did not grow on 1-naphthol, 2-naphthol, anthracene, phenanthrene, indane and indene. Terminal restriction fragment length polymorphism and 16S rRNA gene sequence analyses revealed that the microbial community of the culture was dominated by one bacterial microorganism, which was closely related (99% 16S sequence similarity) to the major organism in the iron-reducing, benzene-degrading enrichment culture BF [ISME J (2007) 1: 643; Int J Syst Evol Microbiol (2010) 60: 686]. The phylogenetic classification supports a new candidate species and genus of Gram-positive spore-forming iron-reducers that can degrade non-substituted aromatic hydrocarbons. It furthermore indicates that Gram-positive microorganisms might also play an important role in anaerobic polycyclic aromatic hydrocarbon-degradation. PMID:22066721

Kleemann, Rita; Meckenstock, Rainer U

2011-12-01

97

In vitro pyrogenicity of Gram-positive bacteria--validation of the kit using fresh human whole blood.  

PubMed

The two conventional tests to detect pyrogen contaminants in injectable pharmaceutical drugs are the Rabbit Model and the Limulus amoebocyte lysate (LAL) test. To replace these models, a new system on human whole blood is developed, using the release of Interleukin 1 beta (IL1beta) after cell stimulation with gram-positive and gram negative pyrogens. The purpose of this study was to validate the ENDOSAFE-IPT kit using the quantitative ELISA enzyme immunoassay. The assay is divided into two parts: blood cell stimulation with Lipopolysaccharides (LPS) and Lipoteichoic acid (LTA) and quantitation of IL1beta using the ELISA method. In each assay, blood from a particular donor were stimulated with the Endotoxin Standard, and with a sample of a commercial antibiotic preparation (Clavulanic acid/Ticarcillin) spiked with the Endotoxin Standard. LTA from Bacillus subtilis and a sample of diphtheria toxoid were also used. At least, six assays were tested. A polynomial regression of the Endotoxin Standard series showed a correlation coefficient greater than 0.99. The spiked antibiotic sample recoveries were 50-121%. The LTA quantitation limit was 0.1 microg/ml and the range of detection of pyrogens from Gram positive diphtheria toxoid was 0.77 to 2.5 EEU/ml. The IL1beta production varied markedly between donors. However the coefficient of variation was less than 20 % intra-assay. In conclusion, the ENDOSAFE-IPT kit can be used for the quantitative and qualitative detection of pyrogens from Gram negative and Gram positive bacteria. PMID:17694641

François, C; Neveu, J; Sauvaire, D; Bonnet, P A; Tissier, M H

2006-08-01

98

Evaluation of the Verigene Gram-positive blood culture nucleic acid test for rapid detection of bacteria and resistance determinants.  

PubMed

Rapid identification of pathogens from blood cultures can decrease lengths of stay and improve patient outcomes. We evaluated the accuracy of the Verigene Gram-positive blood culture (BC-GP) nucleic acid test for investigational use only (Nanosphere, Inc., Northbrook, IL) for the identification of Gram-positive bacteria from blood cultures. The detection of resistance genes (mecA in Staphylococcus aureus and Staphylococcus epidermidis and vanA or vanB in Enterococcus faecium and Enterococcus faecalis) by the BC-GP assay also was assessed. A total of 186 positive blood cultures (in BacT/Alert FA bottles) with Gram-positive cocci observed with Gram staining were analyzed using the BC-GP assay. The BC-GP results were compared with the identification and susceptibility profiles obtained with routine methods in the clinical laboratory. Discordant results were arbitrated with additional biochemical, cefoxitin disk, and repeat BC-GP testing. The initial BC-GP organism identification was concordant with routine method results for 94.6% of the blood cultures. Only 40% of the Streptococcus pneumoniae identifications were correct. The detection of the mecA gene for 69 blood cultures with only S. aureus or S. epidermidis was concordant with susceptibility testing results. For 3 of 6 cultures with multiple Staphylococcus spp., mecA detection was reported but was correlated with oxacillin resistance in a species other than S. aureus or S. epidermidis. The detection of vanA agreed with susceptibility testing results for 45 of 46 cultures with E. faecalis or E. faecium. Comparison of the mean times to results for each organism group showed that BC-GP results were available 31 to 42 h earlier than phenotypic identifications and 41 to 50 h earlier than susceptibility results. PMID:23596240

Wojewoda, Christina M; Sercia, Linda; Navas, Maria; Tuohy, Marion; Wilson, Deborah; Hall, Geraldine S; Procop, Gary W; Richter, Sandra S

2013-07-01

99

Antibacterial Activity of Sphingoid Bases and Fatty Acids against Gram-Positive and Gram-Negative Bacteria  

PubMed Central

There is growing evidence that the role of lipids in innate immunity is more important than previously realized. How lipids interact with bacteria to achieve a level of protection, however, is still poorly understood. To begin to address the mechanisms of antibacterial activity, we determined MICs and minimum bactericidal concentrations (MBCs) of lipids common to the skin and oral cavity—the sphingoid bases d-sphingosine, phytosphingosine, and dihydrosphingosine and the fatty acids sapienic acid and lauric acid—against four Gram-negative bacteria and seven Gram-positive bacteria. Exact Kruskal-Wallis tests of these values showed differences among lipid treatments (P < 0.0001) for each bacterial species except Serratia marcescens and Pseudomonas aeruginosa. d-Sphingosine (MBC range, 0.3 to 19.6 ?g/ml), dihydrosphingosine (MBC range, 0.6 to 39.1 ?g/ml), and phytosphingosine (MBC range, 3.3 to 62.5 ?g/ml) were active against all bacteria except S. marcescens and P. aeruginosa (MBC > 500 ?g/ml). Sapienic acid (MBC range, 31.3 to 375.0 ?g/ml) was active against Streptococcus sanguinis, Streptococcus mitis, and Fusobacterium nucleatum but not active against Escherichia coli, Staphylococcus aureus, S. marcescens, P. aeruginosa, Corynebacterium bovis, Corynebacterium striatum, and Corynebacterium jeikeium (MBC > 500 ?g/ml). Lauric acid (MBC range, 6.8 to 375.0 ?g/ml) was active against all bacteria except E. coli, S. marcescens, and P. aeruginosa (MBC > 500 ?g/ml). Complete killing was achieved as early as 0.5 h for some lipids but took as long as 24 h for others. Hence, sphingoid bases and fatty acids have different antibacterial activities and may have potential for prophylactic or therapeutic intervention in infection.

Fischer, Carol L.; Drake, David R.; Dawson, Deborah V.; Blanchette, Derek R.; Brogden, Kim A.

2012-01-01

100

Antibacterial activity of sphingoid bases and fatty acids against Gram-positive and Gram-negative bacteria.  

PubMed

There is growing evidence that the role of lipids in innate immunity is more important than previously realized. How lipids interact with bacteria to achieve a level of protection, however, is still poorly understood. To begin to address the mechanisms of antibacterial activity, we determined MICs and minimum bactericidal concentrations (MBCs) of lipids common to the skin and oral cavity--the sphingoid bases D-sphingosine, phytosphingosine, and dihydrosphingosine and the fatty acids sapienic acid and lauric acid--against four Gram-negative bacteria and seven Gram-positive bacteria. Exact Kruskal-Wallis tests of these values showed differences among lipid treatments (P < 0.0001) for each bacterial species except Serratia marcescens and Pseudomonas aeruginosa. D-sphingosine (MBC range, 0.3 to 19.6 ?g/ml), dihydrosphingosine (MBC range, 0.6 to 39.1 ?g/ml), and phytosphingosine (MBC range, 3.3 to 62.5 ?g/ml) were active against all bacteria except S. marcescens and P. aeruginosa (MBC > 500 ?g/ml). Sapienic acid (MBC range, 31.3 to 375.0 ?g/ml) was active against Streptococcus sanguinis, Streptococcus mitis, and Fusobacterium nucleatum but not active against Escherichia coli, Staphylococcus aureus, S. marcescens, P. aeruginosa, Corynebacterium bovis, Corynebacterium striatum, and Corynebacterium jeikeium (MBC > 500 ?g/ml). Lauric acid (MBC range, 6.8 to 375.0 ?g/ml) was active against all bacteria except E. coli, S. marcescens, and P. aeruginosa (MBC > 500 ?g/ml). Complete killing was achieved as early as 0.5 h for some lipids but took as long as 24 h for others. Hence, sphingoid bases and fatty acids have different antibacterial activities and may have potential for prophylactic or therapeutic intervention in infection. PMID:22155833

Fischer, Carol L; Drake, David R; Dawson, Deborah V; Blanchette, Derek R; Brogden, Kim A; Wertz, Philip W

2012-03-01

101

Antibacterial activity of oregano (Origanum vulgare Linn.) against gram positive bacteria.  

PubMed

The present investigation is focused on antibacterial potential of infusion, decoction and essential oil of oregano (Origanum vulgare) against 111 Gram-positive bacterial isolates belonging to 23 different species related to 3 genera. Infusion and essential oil exhibited antibacterial activity against Staphylococcus saprophyticus, S. aureus, Micrococcus roseus, M. kristinae, M. nishinomiyaensis, M. lylae, M. luteus, M. sedentarius, M. varians, Bacillus megaterium, B. thuringiensis, B. alvei, B. circulans, B. brevis, B. coagulans, B. pumilus, B. laterosporus, B. polymyxa, B. macerans, B. subtilis, B. firmus, B. cereus and B. lichiniformis. The infusion exhibited maximum activity against B. laterosporus (17.5 mm mean zone of inhibition+/-1.5 Standard deviation) followed by B. polymyxa (17.0 mm+/-2.0 SD) and essential oil of oregano exhibited maximum activity against S. saprophyticus (16.8 mm+/-1.8 SD) followed by B. circulans (14.5 mm+/-0.5 SD). While all these tested isolates were found resistant to decoction of oregano. PMID:19783523

Saeed, Sabahat; Tariq, Perween

2009-10-01

102

Presence and dissemination of the multiresistance gene cfr in Gram-positive and Gram-negative bacteria.  

PubMed

The emergence of the multiresistance gene cfr in staphylococci is of global concern. In addition to conferring resistance to phenicols, lincosamides, pleuromutilins, streptogramin A antibiotics and selected 16-membered macrolides, the cfr gene also confers resistance to the oxazolidinone linezolid. Linezolid is a last-resort antimicrobial agent for the treatment of serious infections in humans caused by resistant Gram-positive bacteria. The cfr gene is often located on plasmids and several cfr-carrying plasmids have been described, which differ in their structure, their size and the presence of additional resistance genes. These plasmids are important vehicles that promote the spread of the cfr gene not only among bacteria of the same species, but also among those of different species and genera. Moreover, the cfr gene has been identified in close proximity to different insertion sequences, which most probably also play an important role in its dissemination. This review summarizes current knowledge on the genetic environment of the multiresistance gene cfr with particular reference to mobile genetic elements and co-located resistance genes that may support its emergence. PMID:23543608

Shen, Jianzhong; Wang, Yang; Schwarz, Stefan

2013-08-01

103

Antimicrobial photodynamic efficiency of novel cationic porphyrins towards periodontal Gram-positive and Gram-negative pathogenic bacteria.  

PubMed

The Gram-negative Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum are major causative agents of aggressive periodontal disease. Due to increase in the number of antibiotic-resistant bacteria, antimicrobial Photodynamic therapy (aPDT) seems to be a plausible alternative. In this work, photosensitization was performed on Gram-positive and Gram-negative bacteria in pure culture using new-age cationic porphyrins, namely mesoimidazolium-substituted porphyrin derivative (ImP) and pyridinium-substituted porphyrin derivative (PyP). The photophysical properties of both the sensitizers including absorption, fluorescence emission, quantum yields of the triplet excited states and singlet oxygen generation efficiencies were evaluated in the context of aPDT application. The studied porphyrins exhibited high ability to accumulate into bacterial cells with complete penetration into early stage biofilms. As compared with ImP, PyP was found to be more effective for photoinactivation of bacterial strains associated with periodontitis, without any signs of dark toxicity, owing to its high photocytotoxicity. PMID:24164211

Prasanth, Chandra Sekhar; Karunakaran, Suneesh C; Paul, Albish K; Kussovski, Vesselin; Mantareva, Vanya; Ramaiah, Danaboyina; Selvaraj, Leslie; Angelov, Ivan; Avramov, Latchezar; Nandakumar, Krishnankutty; Subhash, Narayanan

2014-01-01

104

The molecular switch that activates the cell wall anchoring step of pilus assembly in gram-positive bacteria.  

PubMed

Cell surface pili in gram-positive bacteria orchestrate the colonization of host tissues, evasion of immunity, and the development of biofilms. Recent work revealed that pilus assembly is a biphasic process wherein pilus polymerization is catalyzed by a pilus-specific sortase followed by cell wall anchoring of the pilus that is promoted by the housekeeping sortase. Here, we present molecular genetic and biochemical studies of a heterotrimeric pilus in Corynebacterium diphtheriae, uncovering the molecular switch that terminates pilus polymerization in favor of cell wall anchoring. The prototype pilus contains a major pilin (SpaA) forming the shaft, a tip pilin (SpaC), and another minor pilin (SpaB). Cells lacking SpaB form pilus fibers, but they are largely secreted in the medium, a phenotype also observed when cells lack the housekeeping sortase. Furthermore, the average pilus length is greatly increased in the absence of SpaB. Remarkably, a SpaB mutant that lacks the cell wall sorting signal but contains a critical lysine residue is incorporated in the pilus. However, the resulting pili fail to anchor to the cell wall. We propose that a specific minor pilin acts as the terminal subunit in pilus assembly. Cell wall anchoring ensues when the pilus polymer assembled on the pilus-specific sortase is transferred to the minor pilin presented by the housekeeping sortase via lysine-mediated transpeptidation. PMID:18779588

Mandlik, Anjali; Das, Asis; Ton-That, Hung

2008-09-16

105

Identification and characterization of a new xylanase from Gram-positive bacteria isolated from termite gut (Reticulitermes santonensis).  

PubMed

Termites are world champions at digesting lignocellulosic compounds, thanks to cooperation between their own enzymes and exogenous enzymes from microorganisms. Prokaryotic cells are responsible for a large part of this lignocellulolytic activity. Bacterial enzyme activities have been demonstrated in the higher and the lower termite gut. From five clones of Gram-positive bacteria isolated and identified in a previous work, we constructed a genomic DNA library and performed functional screening for alpha-amylase, beta-glucosidase, and xylanase activities. One candidate, Xyl8B8, showed xylanase activity. Sequence analysis of the genomic insert revealed five complete ORFs on the cloned DNA (5746bp). Among the encoded proteins were a putative endo-1,4-beta-xylanase (XylB8) belonging to glycoside hydrolase family 11 (GH11). On the basis of sequence analyses, genomic DNA organization, and phylogenetic analysis, the insert was shown to come from an actinobacterium. The mature xylanase (mXylB8) was expressed in Escherichia coli and purified by affinity chromatography and detected by zymogram analysis after renaturing. It showed maximal xylanase activity in sodium acetate buffer, pH 5.0 at 55 °C. Its activity was increased by reducing agents and decreased by Cu(2+), some detergents, and chelating agents. Its substrate specificity appeared limited to xylan. PMID:22487213

Mattéotti, Christel; Bauwens, Julien; Brasseur, Catherine; Tarayre, Cédric; Thonart, Philippe; Destain, Jacqueline; Francis, Frédéric; Haubruge, Eric; De Pauw, Edwin; Portetelle, Daniel; Vandenbol, Micheline

2012-06-01

106

Rapid Discrimination of Gram-Positive and Gram-Negative Bacteria in Liquid Samples by Using NaOH-Sodium Dodecyl Sulfate Solution and Flow Cytometry  

PubMed Central

Background For precise diagnosis of urinary tract infections (UTI), and selection of the appropriate prescriptions for their treatment, we explored a simple and rapid method of discriminating gram-positive and gram-negative bacteria in liquid samples. Methodology/Principal Findings We employed the NaOH-sodium dodecyl sulfate (SDS) solution conventionally used for plasmid extraction from Escherichia coli and the automated urine particle analyzer UF-1000i (Sysmex Corporation) for our novel method. The NaOH-SDS solution was used to determine differences in the cell wall structures between gram-positive and gram-negative bacteria, since the tolerance to such chemicals reflects the thickness and structural differences of bacterial cell walls. The UF-1000i instrument was used as a quantitative bacterial counter. We found that gram-negative bacteria, including E. coli, in liquid culture could easily be lysed by direct addition of equal volumes of NaOH-SDS solution. In contrast, Enterococcus faecalis, which is a gram-positive bacterium, could not be completely lysed by the solution. We then optimized the reaction time of the NaOH-SDS treatment at room temperature by using 3 gram-positive and 4 gram-negative bacterial strains and determined that the optimum reaction time was 5 min. Finally, in order to evaluate the generalizability of this method, we treated 8 gram-positive strains and 8 gram-negative strains, or 4 gram-positive and 4 gram-negative strains incubated in voluntary urine from healthy volunteers in the same way and demonstrated that all the gram-positive bacteria were discriminated quantitatively from gram negative bacteria using this method. Conclusions/Significance Using our new method, we could easily discriminate gram-positive and gram-negative bacteria in liquid culture media within 10 min. This simple and rapid method may be useful for determining the treatment course of patients with UTIs, especially for those without a prior history of UTIs. The method may be easily applied in order to obtain additional information for clinical prescriptions from bacteriuria.

Wada, Atsushi; Kono, Mari; Kawauchi, Sawako; Takagi, Yuri; Morikawa, Takashi; Funakoshi, Kunihiro

2012-01-01

107

Obtaining and characterization of DNA-containing micromummies of yeasts and gram-positive bacteria with enhanced cell wall permeability: Application in PCR  

Microsoft Academic Search

The procedure of obtaining DNA-containing cell envelopes (“micromummies”) of bacteria, yeasts, and fungi using chaotropic\\u000a salts has been developed previously and the possibility of their direct application in PCR has been demonstrated. The fine\\u000a structure of micromummies has been studied by electron microscopic methods. This work has demonstrated that additional treatment\\u000a of micromummies of yeasts and gram-positive bacteria with proteinase

V. N. Danilevich; V. I. Duda; N. E. Suzina; E. V. Grishin

2007-01-01

108

Novel Bacterial Lipoprotein Structures Conserved in Low-GC Content Gram-positive Bacteria Are Recognized by Toll-like Receptor 2*  

PubMed Central

Bacterial lipoproteins/lipopeptides inducing host innate immune responses are sensed by mammalian Toll-like receptor 2 (TLR2). These bacterial lipoproteins are structurally divided into two groups, diacylated or triacylated lipoproteins, by the absence or presence of an amide-linked fatty acid. The presence of diacylated lipoproteins has been predicted in low-GC content Gram-positive bacteria and mycoplasmas based on the absence of one modification enzyme in their genomes; however, we recently determined triacylated structures in low-GC Gram-positive Staphylococcus aureus, raising questions about the actual lipoprotein structure in other low-GC content Gram-positive bacteria. Here, through intensive MS analyses, we identified a novel and unique bacterial lipoprotein structure containing an N-acyl-S-monoacyl-glyceryl-cysteine (named the lyso structure) from low-GC Gram-positive Enterococcus faecalis, Bacillus cereus, Streptococcus sanguinis, and Lactobacillus bulgaricus. Two of the purified native lyso-form lipoproteins induced proinflammatory cytokine production from mice macrophages in a TLR2-dependent and TLR1-independent manner but with a different dependence on TLR6. Additionally, two other new lipoprotein structures were identified. One is the “N-acetyl” lipoprotein structure containing N-acetyl-S-diacyl-glyceryl-cysteine, which was found in five Gram-positive bacteria, including Bacillus subtilis. The N-acetyl lipoproteins induced the proinflammatory cytokines through the TLR2/6 heterodimer. The other was identified in a mycoplasma strain and is an unusual diacyl lipoprotein structure containing two amino acids before the lipid-modified cysteine residue. Taken together, our results suggest the existence of novel TLR2-stimulating lyso and N-acetyl forms of lipoproteins that are conserved in low-GC content Gram-positive bacteria and provide clear evidence for the presence of yet to be identified key enzymes involved in the bacterial lipoprotein biosynthesis.

Kurokawa, Kenji; Ryu, Kyoung-Hwa; Ichikawa, Rie; Masuda, Akiko; Kim, Min-Su; Lee, Hanna; Chae, Jun-Ho; Shimizu, Takashi; Saitoh, Tatsuya; Kuwano, Koichi; Akira, Shizuo; Dohmae, Naoshi; Nakayama, Hiroshi; Lee, Bok Luel

2012-01-01

109

Acylation of SC4 dodecapeptide increases bactericidal potency against Gram-positive bacteria, including drug-resistant strains.  

PubMed Central

We have conjugated dodecyl and octadecyl fatty acids to the N-terminus of SC4, a potently bactericidal, helix-forming peptide 12-mer (KLFKRHLKWKII), and examined the bactericidal activities of the resultant SC4 'peptide-amphiphile' molecules. SC4 peptide-amphiphiles showed up to a 30-fold increase in bactericidal activity against Gram-positive strains (Staphylococcus aureus, Streptococcus pyogenes and Bacillus anthracis), including S. aureus strains resistant to conventional antibiotics, but little or no increase in bactericidal activity against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Fatty acid conjugation improved endotoxin (lipopolysaccharide) neutralization by 3- to 6-fold. Although acylation somewhat increased lysis of human erythrocytes, it did not increase lysis of endothelial cells, and the haemolytic effects occurred at concentrations 10- to 100-fold higher than those required for bacterial cell lysis. For insight into the mechanism of action of SC4 peptide-amphiphiles, CD, NMR and fluorescence spectroscopy studies were performed in micelle and liposome models of eukaryotic and bacterial cell membranes. CD indicated that SC4 peptide-amphiphiles had the strongest helical tendencies in liposomes mimicking bacterial membranes, and strong membrane integration of the SC4 peptide-amphiphiles was observed using tryptophan fluorescence spectroscopy under these conditions; results that correlated with the increased bactericidal activities of SC4 peptide-amphiphiles. NMR structural analysis in micelles demonstrated that the two-thirds of the peptide closest to the fatty acid tail exhibited a helical conformation, with the positively-charged side of the amphipathic helix interacting more with the model membrane surface. These results indicate that conjugation of a fatty acid chain to the SC4 peptide enhances membrane interactions, stabilizes helical structure in the membrane-bound state and increases bactericidal potency.

Lockwood, Nathan A; Haseman, Judith R; Tirrell, Matthew V; Mayo, Kevin H

2004-01-01

110

Quantification of Gram-positive bacteria: adaptation and evaluation of a preparation strategy using high amounts of clinical tissue  

PubMed Central

Background A preparation method for quantification of bacteria in tissues is obligatory to reduce tissue mass, concentrate the target, purify, remove inhibitory substances and to achieve constant target recovery rates. No preparation method has been available until now for a high mass of tissue applicable for routine use and analytical veterinary diagnostics. Results This study describes an easy-to-use tissue preparation protocol to quantify Gram-positive bacteria from a large volume of tissue matrix. A previously published sample preparation method (Matrix-Lysis) from food science was successfully adapted for clinical use on tissues from pigs, including cerebrum, spinal cord, lung, liver, ileum, colon, caecum, kidney and muscle tissue. This tissue preparation method now permits quantification of pathogens from 5 g of organic matrix, which is a 20–200 fold increase by weight compared to other methods. It is based on solubilization of the sample matrix with either a chaotrope plus detergent or divalent salts as solubilization agents. The method was designed as a modular system, offering the possibility to change lysis buffers, according to tissue solubilization characteristics and the intended detection method (molecular or culture). Using Listeria monocytogenes as model organism, viable cell quantification or DNA extraction and quantitative real-time PCR were performed after Matrix-Lysis to determine recovery rates and detection limit (LOD). The adapted Matrix-Lysis protocol resulted in high recovery rates (mean value: 76%?±?39%) for all tested organs, except kidney, and recovery was constant over 5 log scales for all tested buffer systems. The LOD for Matrix-Lysis with subsequent plate count method (PCM) was as low as 1 CFU/5 g, while for qPCR based detection the LOD was 102 bacterial cell equivalents (BCE)/5 g for two buffer systems. Conclusions This tissue preparation is inexpensive and can be easily used for routine and analytical veterinary diagnostics. Inoculation studies or hazard assessments can profit from this tissue preparation method and it is anticipated that this study will be a valuable source for further research on tissue preparation strategies.

2014-01-01

111

Expanding the use of a fluorogenic method to determine activity and mode of action of Bacillus thuringiensis bacteriocins against Gram-positive and Gram-negative bacteria.  

PubMed

Previously we described a rapid fluorogenic method to measure the activity of five bacteriocins produced by Mexican strains of Bacillus thuringiensis against B. cereus 183. Here we standardize this method to efficiently determine the activity of bacteriocins against both Gram-positive and Gram-negative bacteria. It was determined that the crucial parameter required to obtain reproducible results was the number of cells used in the assay, that is, ~4 × 10(8) cell/mL and ~7 × 10(8) cell/mL, respectively, for target Gram-positive and Gram-negative bacteria. Comparative analyses of the fluorogenic and traditional well-diffusion assays showed correlation coefficients of 0.88 to 0.99 and 0.83 to 0.99, respectively, for Gram-positive and Gram-negative bacteria. The fluorogenic method demonstrated that the five bacteriocins of B. thuringiensis have bacteriolytic and bacteriostatic activities against all microorganisms tested, including clinically significant bacteria such as Listeria monocytogenes, Proteus vulgaris, and Shigella flexneri reported previously to be resistant to the antimicrobials as determined using the well-diffusion protocol. These results demonstrate that the fluorogenic assay is a more sensitive, reliable, and rapid method when compared with the well-diffusion method and can easily be adapted in screening protocols for bacteriocin production by other microorganisms. PMID:22919330

de la Fuente-Salcido, Norma M; Barboza-Corona, J Eleazar; Espino Monzón, A N; Pacheco Cano, R D; Balagurusamy, N; Bideshi, Dennis K; Salcedo-Hernández, Rubén

2012-01-01

112

Expanding the Use of a Fluorogenic Method to Determine Activity and Mode of Action of Bacillus thuringiensis Bacteriocins Against Gram-Positive and Gram-Negative Bacteria  

PubMed Central

Previously we described a rapid fluorogenic method to measure the activity of five bacteriocins produced by Mexican strains of Bacillus thuringiensis against B. cereus 183. Here we standardize this method to efficiently determine the activity of bacteriocins against both Gram-positive and Gram-negative bacteria. It was determined that the crucial parameter required to obtain reproducible results was the number of cells used in the assay, that is, ~4?×?108?cell/mL and ~7?×?108?cell/mL, respectively, for target Gram-positive and Gram-negative bacteria. Comparative analyses of the fluorogenic and traditional well-diffusion assays showed correlation coefficients of 0.88 to 0.99 and 0.83 to 0.99, respectively, for Gram-positive and Gram-negative bacteria. The fluorogenic method demonstrated that the five bacteriocins of B. thuringiensis have bacteriolytic and bacteriostatic activities against all microorganisms tested, including clinically significant bacteria such as Listeria monocytogenes, Proteus vulgaris, and Shigella flexneri reported previously to be resistant to the antimicrobials as determined using the well-diffusion protocol. These results demonstrate that the fluorogenic assay is a more sensitive, reliable, and rapid method when compared with the well-diffusion method and can easily be adapted in screening protocols for bacteriocin production by other microorganisms.

de la Fuente-Salcido, Norma M.; Barboza-Corona, J. Eleazar; Espino Monzon, A. N.; Pacheco Cano, R. D.; Balagurusamy, N.; Bideshi, Dennis K.; Salcedo-Hernandez, Ruben

2012-01-01

113

Detection of heavy metal ion resistance genes in Gram-positive and Gram-negative bacteria isolated from a lead-contaminated site  

Microsoft Academic Search

Resistance to a range of heavy metal ions wasdetermined for lead-resistant and other bacteria whichhad been isolated from a battery-manufacturing sitecontaminated with high concentrations of lead. Several Gram-positive (belonging to the genera Arthrobacter and Corynebacterium) andGram-negative (Alcaligenes species) isolateswere resistant to lead, mercury, cadmium, cobalt,zinc and copper, although the levels of resistance tothe different metal ions were specific for eachisolate.

Suzana Trajanovska; Margaret L. Britz; Mrinal Bhave

1997-01-01

114

Lactobacillus plantarum gene clusters encoding putative cell-surface protein complexes for carbohydrate utilization are conserved in specific gram-positive bacteria  

Microsoft Academic Search

BACKGROUND: Genomes of gram-positive bacteria encode many putative cell-surface proteins, of which the majority has no known function. From the rapidly increasing number of available genome sequences it has become apparent that many cell-surface proteins are conserved, and frequently encoded in gene clusters or operons, suggesting common functions, and interactions of multiple components. RESULTS: A novel gene cluster encoding exclusively

Roland Siezen; Jos Boekhorst; Lidia Muscariello; Douwe Molenaar; Bernadet Renckens; Michiel Kleerebezem

2006-01-01

115

Cell lysis and DNA extraction of gram-positive and gram-negative bacteria from whole blood in a disposable microfluidic chip  

Microsoft Academic Search

Sepsis caused by gram positive and gram negative bacteria is the leading cause of death in noncoronary ICUs and the tenth leading cause of death in the United States. We have developed a microfluidic sample preparation platform for rapid on-chip detection of infectious organisms for point-of-care diagnostics. The microfluidic chips are made of a robust thermoplastic and can be easily

Madhumita Mahalanabis; Hussam Al-Muayad; M. Dominika Kulinski; Dave Altmanb; Catherine M. Klapperichac

2009-01-01

116

A new hybrid bacteriocin, Ent35-MccV, displays antimicrobial activity against pathogenic Gram-positive and Gram-negative bacteria  

PubMed Central

Bacteriocins and microcins are ribosomally synthesized antimicrobial peptides that are usually active against phylogenetically related bacteria. Thus, bacteriocins are active against Gram-positive while microcins are active against Gram-negative bacteria. The narrow spectrum of action generally displayed by bacteriocins from lactic acid bacteria represents an important limitation for the application of these peptides as clinical drugs or as food biopreservatives. The present study describes the design and expression of a novel recombinant hybrid peptide combining enterocin CRL35 and microcin V named Ent35–MccV. The chimerical bacteriocin displayed antimicrobial activity against enterohemorrhagic Escherichia coli and Listeria monocytogenes clinical isolates, among other pathogenic bacteria. Therefore, Ent35–MccV may find important applications in food or pharmaceutical industries.

Acuna, Leonardo; Picariello, Gianluca; Sesma, Fernando; Morero, Roberto D.; Bellomio, Augusto

2012-01-01

117

Multiplex Identification of Gram-Positive Bacteria and Resistance Determinants Directly from Positive Blood Culture Broths: Evaluation of an Automated Microarray-Based Nucleic Acid Test  

PubMed Central

Background A multicenter study was conducted to evaluate the diagnostic accuracy (sensitivity and specificity) of the Verigene Gram-Positive Blood Culture Test (BC-GP) test to identify 12 Gram-positive bacterial gene targets and three genetic resistance determinants directly from positive blood culture broths containing Gram-positive bacteria. Methods and Findings 1,252 blood cultures containing Gram-positive bacteria were prospectively collected and tested at five clinical centers between April, 2011 and January, 2012. An additional 387 contrived blood cultures containing uncommon targets (e.g., Listeria spp., S. lugdunensis, vanB-positive Enterococci) were included to fully evaluate the performance of the BC-GP test. Sensitivity and specificity for the 12 specific genus or species targets identified by the BC-GP test ranged from 92.6%–100% and 95.4%–100%, respectively. Identification of the mecA gene in 599 cultures containing S. aureus or S. epidermidis was 98.6% sensitive and 94.3% specific compared to cefoxitin disk method. Identification of the vanA gene in 81 cultures containing Enterococcus faecium or E. faecalis was 100% sensitive and specific. Approximately 7.5% (87/1,157) of single-organism cultures contained Gram-positive bacteria not present on the BC-GP test panel. In 95 cultures containing multiple organisms the BC-GP test was in 71.6% (68/95) agreement with culture results. Retrospective analysis of 107 separate blood cultures demonstrated that identification of methicillin resistant S. aureus and vancomycin resistant Enterococcus spp. was completed an average of 41.8 to 42.4 h earlier using the BC-GP test compared to routine culture methods. The BC-GP test was unable to assign mecA to a specific organism in cultures containing more than one Staphylococcus isolate and does not identify common blood culture contaminants such as Micrococcus, Corynebacterium, and Bacillus. Conclusions The BC-GP test is a multiplex test capable of detecting most leading causes of Gram-positive bacterial blood stream infections as well as genetic markers of methicillin and vancomycin resistance directly from positive blood cultures. Please see later in the article for the Editors' Summary

Buchan, Blake W.; Ginocchio, Christine C.; Manii, Ryhana; Cavagnolo, Robert; Pancholi, Preeti; Swyers, Lettie; Thomson, Richard B.; Anderson, Christopher; Kaul, Karen; Ledeboer, Nathan A.

2013-01-01

118

Fructose Utilization in Lactococcus lactis as a Model for Low-GC Gram-Positive Bacteria: Its Regulator, Signal, and DNA-Binding Site  

PubMed Central

In addition to its role as carbon and energy source, fructose metabolism was reported to affect other cellular processes, such as biofilm formation by streptococci and bacterial pathogenicity in plants. Fructose genes encoding a 1-phosphofructokinase and a phosphotransferase system (PTS) fructose-specific enzyme IIABC component reside commonly in a gene cluster with a DeoR family regulator in various gram-positive bacteria. We present a comprehensive study of fructose metabolism in Lactococcus lactis, including a systematic study of fru mutants, global messenger analysis, and a molecular characterization of its regulation. The fru operon is regulated at the transcriptional level by both FruR and CcpA and at the metabolic level by inducer exclusion. The FruR effector is fructose-1-phosphate (F1P), as shown by combined analysis of transcription and measurements of the intracellular F1P pools in mutants either unable to produce this metabolite or accumulating it. The regulation of the fru operon by FruR requires four adjacent 10-bp direct repeats. The well-conserved organization of the fru promoter region in various low-GC gram-positive bacteria, including CRE boxes as well as the newly defined FruR motif, suggests that the regulation scheme defined in L. lactis could be applied to these bacteria. Transcriptome profiling of fruR and fruC mutants revealed that the effect of F1P and FruR regulation is limited to the fru operon in L. lactis. This result is enforced by the fact that no other targets for FruR were found in the available low-GC gram-positive bacteria genomes, suggesting that additional phenotypical effects due to fructose metabolism do not rely directly on FruR control, but rather on metabolism.

Barriere, Charlotte; Veiga-da-Cunha, Maria; Pons, Nicolas; Guedon, Eric; van Hijum, Sacha A. F. T.; Kok, Jan; Kuipers, Oscar P.; Ehrlich, Dusko S.; Renault, Pierre

2005-01-01

119

Disinfection of gram-negative and gram-positive bacteria using D ynaJ ets® hydrodynamic cavitating jets  

Microsoft Academic Search

Cavitating jet technologies (DynaJets®) were investigated as a means of disinfection of gram-negative Escherichia coli, Klebsiellapneumoniae, Pseudomonas syringae, and Pseudomonas aeruginosa, and gram-positive Bacillus subtilis. The hydrodynamic cavitating jets were found to be very effective in reducing the concentrations of all of these species. In general, the observed rates of disinfection of gram-negative species were higher than for gram-positive species.

Gregory Loraine; Georges Chahine; Chao-Tsung Hsiao; Jin-Keun Choi; Patrick Aley

120

Alternating electric fields combined with activated carbon for disinfection of Gram negative and Gram positive bacteria in fluidized bed electrode system.  

PubMed

Strong electric fields for disinfection of wastewaters have been employed already for several decades. An innovative approach combining low strength (7 V/cm) alternating electric fields with a granular activated carbon fluidized bed electrode (FBE) for disinfection was presented recently. For disinfection performance of FBE several pure microbial cultures were tested: Bacillus subtilis, Bacillus subtilis subsp. subtilis, Enterococcus faecalis as representatives from Gram positive bacteria and Erwinia carotovora, Pseudomonas luteola, Pseudomonas fluorescens and Escherichia coli YMc10 as representatives from Gram negative bacteria. The alternating electric field amplitude and shape were kept constant. Only the effect of alternating electric field frequency on disinfection performance was investigated. From the bacteria tested, the Gram negative strains were more susceptible and the Gram positive microorganisms were more resistant to FBE disinfection. The collected data indicate that the efficiency of disinfection is frequency and strain dependent. During 6 h of disinfection, the decrease above 2 Log units was achieved with P. luteola and E. coli at 10 kHz and at dual frequency shift keying (FSK) modulated signal with frequencies of 10 kHz and 140 kHz. FBE technology appears to offer a new way for selective bacterial disinfection, however further optimizations are needed on treatment duration, and energy input, to improve effectiveness. PMID:24012021

Racyte, Justina; Bernard, Séverine; Paulitsch-Fuchs, Astrid H; Yntema, Doekle R; Bruning, Harry; Rijnaarts, Huub H M

2013-10-15

121

Antibiotic resistance patterns in gram-negative and gram-positive bacteria causing septicemia in newborns in León, Nicaragua: correlation with environmental samples.  

PubMed

The aim of this study was to identify the bacteria causing neonatal septicemia in a neonatal intensive care unit (NICU) in León, Nicaragua and its relation with bacteria isolated from the environment at the NICU. Our data showed that 74% (34/46) of the bacteria related to newborns with septicemia were Gram-negative and highly resistant to beta-lactams (>85%) and aminoglycosides (80%), leading to treatment failure in 10 neonates with fatal outcome. Although, the prevalence of Gram-positive bacteria (26%) was lower than Gram-negative bacteria, Staphylococcus epidermidis was related to the death of three newborns. No clonal similarity was found among Enterobacter cloacae , Escherichia coli and Serratia liquefaciens isolated from the neonates with septicemia and the NICU environment. However, in order to improve the outcome for neonates with septicemia, infection control practices and appropriate empirical therapy should be considered to reduce the high prevalence of extended-spectrum beta-lactamase (ESBL)-producing Gram-negative bacteria isolated from neonates with septicemia (80%) and from the NICU environment (34%). PMID:20227989

Amaya, E; Caceres, M; Fanc, H; Torres Ramirez, A; Palmgren, A-C; Nord, C E; Weintraub, A

2010-02-01

122

Systematic review of membrane components of gram-positive bacteria responsible as pyrogens for inducing human monocyte/macrophage cytokine release.  

PubMed

Fifty years after the elucidation of lipopolysaccharides (LPS, endotoxin) as the principal structure of Gram-negative bacteria activating the human immune system, its Gram-positive counterpart is still under debate. Pyrogen tests based on the human monocyte activation have been validated for LPS detection as an alternative to the rabbit test and, increasingly, the limulus amebocyte lysate test. For full replacement, international validations with non-endotoxin pyrogens are in preparation. Following evidence-based medicine approaches, a systematic review of existing evidence as to the structural nature of the Gram-positive pyrogen was undertaken. For the three major constituents suggested, i.e., peptidoglycan, lipoteichoic acids (LTA), and bacterial lipoproteins (LP), the questions to be answered and a search strategy for relevant literature was developed, starting in MedLine. The evaluation was based on the Koch-Dale criteria for a mediator of an effect. A total of 380 articles for peptidoglycan, 391 for LP, and 285 for LTA were retrieved of which 12, 8, and 24, respectively, fulfilled inclusion criteria. The compiled data suggest that for peptidoglycan two Koch-Dale criteria are fulfilled, four for LTA, and two for bacterial LP. In conclusion, based on the best currently available evidence, LTA is the only substance that fulfills all criteria. LTA has been isolated from a large number of bacteria, results in cytokine release patterns inducible also with synthetic LTA. Reduction in bacterial cytokine induction with an inhibitor for LTA was shown. However, this systematic review cannot exclude the possibility that other stimulatory compounds complement or substitute for LTA in being the counterpart to LPS in some Gram-positive bacteria. PMID:22529809

Rockel, Christoph; Hartung, Thomas

2012-01-01

123

Charge effect on the photoinactivation of Gram-negative and Gram-positive bacteria by cationic meso-substituted porphyrins  

Microsoft Academic Search

BACKGROUND: In recent times photodynamic antimicrobial therapy has been used to efficiently destroy Gram (+) and Gram (-) bacteria using cationic porphyrins as photosensitizers. There is an increasing interest in this approach, namely in the search of photosensitizers with adequate structural features for an efficient photoinactivation process. In this study we propose to compare the efficiency of seven cationic porphyrins

Eliana Alves; Liliana Costa; Carla MB Carvalho; João PC Tomé; Maria A Faustino; Maria GPMS Neves; Augusto C Tomé; José AS Cavaleiro; Ângela Cunha; Adelaide Almeida

2009-01-01

124

Gram-positive bacteria are a major reservoir of Class 1 antibiotic resistance integrons in poultry litter  

Microsoft Academic Search

Reversing the spread of antibiotic multiresistant bacteria is hampered by ignorance of the natural history of resistance genes, the mobile elements carrying them, and the bacterial hosts harboring them. Using traditional cultivation and cultivation-independent molecular techniques, we quantified antibiotic resistance genes and mobile elements called integrons in poultry house litter from commercial poultry farms. Unexpectedly, the major reservoir for Class

Sobhan Nandi; John J. Maurer; Charles Hofacre; Anne O. Summers

2004-01-01

125

Antimicrobial and Efflux Pump Inhibitory Activity of Caffeoylquinic Acids from Artemisia absinthium against Gram-Positive Pathogenic Bacteria  

Microsoft Academic Search

Background: Traditional antibiotics are increasingly suffering from the emergence of multidrug resistance amongst pathogenic bacteria leading to a range of novel approaches to control microbial infections being investigated as potential alternative treatments. One plausible antimicrobial alternative could be the combination of conventional antimicrobial agents\\/antibiotics with small molecules which block multidrug efflux systems known as efflux pump inhibitors. Bioassay- driven purification

Yiannis C. Fiamegos; Panagiotis L. Kastritis; Vassiliki Exarchou; Haley Han; Alexandre M. J. J. Bonvin; Jacques Vervoort; Kim Lewis; Michael R. Hamblin; George P. Tegos

2011-01-01

126

Physico-Chemical-Managed Killing of Penicillin-Resistant Static and Growing Gram-Positive and Gram-Negative Vegetative Bacteria  

NASA Technical Reports Server (NTRS)

Systems and methods for the use of compounds from the Hofmeister series coupled with specific pH and temperature to provide rapid physico-chemical-managed killing of penicillin-resistant static and growing Gram-positive and Gram-negative vegetative bacteria. The systems and methods represent the more general physico-chemical enhancement of susceptibility for a wide range of pathological macromolecular targets to clinical management by establishing the reactivity of those targets to topically applied drugs or anti-toxins.

Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor); Defalco, Francis G. (Inventor); Farris, III, Alex F. (Inventor)

2012-01-01

127

Antibacterial activity of Acinetobacter baumannii phage ?AB2 endolysin (LysAB2) against both gram-positive and gram-negative bacteria.  

PubMed

To investigate the nature and origin of the antibacterial activity of the lytic phage ?AB2 toward Acinetobacter baumannii, we successfully isolated and characterized a novel phage lysozyme (endolysin) from ?AB2 and named it LysAB2. To analyze antibacterial activity of LysAB2, the complete LysAB2 and two deletion derivatives were constructed, purified and characterized. Zymographic assays showed that only the intact LysAB2 could lyse the peptidoglycan of A. baumannii and the Staphylococcus aureus cell wall. Antibacterial analysis also showed that only the intact LysAB2 retained the complete bactericidal activity. When applied exogenously, LysAB2 exhibited a broad bacteriolytic activity against a number of Gram-negative and Gram-positive bacteria. Thermostability assays indicated that LysAB2 was stable at 20?40 °C. Its optimal pH was 6.0, and it was active from pH 4 to 8. Scanning electron microscopy revealed that exposure to 500 ?gml(-1) LysAB2 for up to 60 min caused a remarkable modification of the cell shape of the bacteria. Treating bacteria with LysAB2 clearly enhanced permeation of the bacterial cytoplasmic membrane. These results indicate that LysAB2 is an effective lysozyme against bacteria, and they suggest that it is a good candidate for a therapeutic/disinfectant agent to control nosocomial infections caused by multiple drug-resistant bacteria. PMID:21264466

Lai, Meng-Jiun; Lin, Nien-Tsung; Hu, Anren; Soo, Po-Chi; Chen, Li-Kuang; Chen, Long-Hui; Chang, Kai-Chih

2011-04-01

128

The potent antimicrobial properties of cell penetrating peptide-conjugated silver nanoparticles with excellent selectivity for Gram-positive bacteria over erythrocytes  

NASA Astrophysics Data System (ADS)

Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (Gram-positive Bacillus subtilis, Gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects.Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (Gram-positive Bacillus subtilis, Gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr34254a

Liu, Lihong; Yang, Jun; Xie, Jianping; Luo, Zhentao; Jiang, Jiang; Yang, Yi Yan; Liu, Shaomin

2013-04-01

129

The RepA_N replicons of Gram-positive bacteria: a family of broadly distributed but narrow host range plasmids  

PubMed Central

The pheromone-responsive conjugative plasmids of Enterococcus faecalis and the multi-resistance plasmids pSK1 and pSK41 of Staphylococcus aureus are among the best studied plasmids native to Gram-positive bacteria. Although these plasmids seem largely restricted to their native hosts, protein sequence comparison of their replication initiator proteins indicates that they are clearly related. Homology searches indicate that these replicons are representatives of a large family of plasmids and a few phage that are widespread among the low G+C Gram-positive bacteria. We propose to name this family the RepA_N family of replicons after the annotated conserved domain that the initiator protein contains. Detailed sequence comparisons indicate that the initiator protein phylogeny is largely congruent with that of the host, suggesting that the replicons have evolved along with their current hosts and that intergeneric transfer has been rare. However, related proteins were identified on chromosomal regions bearing characteristics indicative of ICE elements, and the phylogeny of these proteins displayed evidence of more frequent intergeneric transfer. Comparison of stability determinants associated with the RepA_N replicons suggests that they have a modular evolution as has been observed in other plasmid families.

Weaver, Keith E.; Kwong, Stephen M.; Firth, Neville; Francia, Maria Victoria

2009-01-01

130

Structure-Activity Relationships of 3,3?-Phenylmethylene-bis-4-hydroxycoumarins: Selective and Potent Inhibitors of Gram-Positive Bacteria  

PubMed Central

Dicoumarols and coumarin derivatives have shown a variety of pharmaceutical activities and have been found to be potent inhibitor for the NAD(P)H-dependent flavoproteins. In this report, dicoumarol and its derivatives containing the substituted benzene ring at the methylenebis position were synthesized and evaluated for their antibacterial activity against gram-positive bacteria: Staphylococcus aureus and Bacillus subtilis, and gram-negative bacteria: Escherichia coli and Klebsiella sp. The results showed that the synthesized dicoumarols affect cell growth but are selective against gram-positive over gram-negative bacterial cells. However, for most derivatives, the substitution of steric bulky benzene group on the methylenebis position appears to decrease in the efficacy of antibacterial effect. This finding is roughly described by the predicted poorer docked structure of the derivatives to a homology model of S. aureus flavoprotein. 3D-QSAR study highlighted structural features around the substituted benzene ring of dicoumarols as the antibacterial activity. CoMFA and CoMSIA contour maps support the idea that steric repulsion at the para position could diminish the antibacterial activity. The results of this study provide a better understanding of the molecular basis for the antibacterial activity of dicoumarols.

Chavasiri, Warinthorn

2013-01-01

131

Effects of cell structure of gram-positive and gram-negative bacteria based on their dielectric properties  

Microsoft Academic Search

Current procedures for the identification and characterization of microorganisms are based on complex and time-consuming protocols. Here, we hypothesize that the distinct cellular composition of microorganisms could be identified by dielectric spectroscopy. Gram-positive and Gram-negative bacterial strain permittivity measurement was performed using a network analyzer and a coaxial probe in the frequency range from 50 MHz to 300 MHz. All

Katja Dahlke; Christiane Geyer; Stephan Dees; Marko Helbig; Jurgen Sachs; Francesco Scotto di Clemente; Matthias Hein; Werner Alois Kaiser; Ingrid Hilger

2012-01-01

132

Unravelling a vicious circle: animal feed marketed in Costa Rica contains irregular concentrations of tetracyclines and abundant oxytetracycline-resistant Gram-positive bacteria.  

PubMed

Diverse tetracyclines are used to prevent and control bacterial infections in livestock and farmed fish. These drugs are administered through the diet, but farmers seldom check whether feed contains antibiotic-resistant bacteria that may colonise their crops or transfer their resistance traits to species of veterinary relevance. To examine whether antibiotic dosage defines the abundance of antibiotic-resistant bacteria in animal feed, we determined the concentration of parental compounds and epimers of oxytetracycline (OTC), doxycycline, tetracycline and chlortetracycline, as well as the abundance and resistance level of OTC-resistant bacteria in samples of fish (n = 21), poultry (n = 21), swine (n = 21), and shrimp feed (n = 21) marketed in Costa Rica. Fish feed contained the highest amounts of tetracyclines (119-8365 mg kg(-1)) and the largest proportion of bacteria resistant to 10 ?g ml(-1) (1.8-92.4%) or 100 ?g ml(-1) of OTC (12.5-63.8%). Poultry (78-438 mg kg(-1)) and swine (41-1076 mg kg(-1)) feed had intermediate concentrations of tetracyclines and OTC-resistant bacteria (0.2-66% and 0.3-49%, respectively), whereas shrimp feed showed the lowest amounts of tetracyclines (21.5-50.3 mg kg(-1)), no OTC and no culturable OTC-resistant bacteria. In line with these results, the MIC50 of OTC for 150 isolates from fish and poultry feed was > 256 µg ml(-1), while that of 150 bacteria isolated from swine feed was 192 µg ml(-1). Phenotypic tests, fatty acid profiles and proteotypic analyses by matrix-assisted laser desorption/ionisation-time of flight mass-spectroscopy revealed that most OTC-resistant isolates were Gram-positive bacteria of low G+C% content from the genera Staphylococcus and Bacillus. Clear correlations between OTC dosage and feed colonisation with OTC-resistant bacteria were seen in medicated feed for fish (r = 0.179-0.651). Nonetheless, some unmedicated feed for fish, swine and poultry contained large populations of OTC-resistant bacteria, suggesting that raw materials and manufacturing processes may also influence carriage of OTC-resistant bacteria in animal feed. PMID:24660748

Granados-Chinchilla, Fabio; Alfaro, Margarita; Chavarría, Guadalupe; Rodríguez, César

2014-06-01

133

Anti-bacterial performance of azithromycin nanoparticles as colloidal drug delivery system against different gram-negative and gram-positive bacteria  

PubMed Central

Purpose: Azithromycin (AZI) is a new macrolide antibiotic with a better activity against intracellular gram negative bacteria in comparison with Erythromycin. The purpose of this research was to prepare AZI nanoparticles (NPs) using PLGA polymer and to compare the effectiveness of prepared nanoparticles with untreated AZI solution. Methods: AZI NPs were prepared by Modified Quasi-Emulsion Solvent Diffusion method. The antibacterial activities of prepared NPs in comparison with AZI solution were assayed against indicator bacteria of Escherichia coli (PTCC 1330), Haemophilus influenzae (PTCC 1623) and Streptococcus pneumoniae (PTCC 1240) using agar well diffusion. Inhibition zone diameters (IZD) of nano-formulation were compared to the corresponding untreated AZI. Mean Inhibitory Concentration (MIC) values of AZI were also determined using serial dilution method in nutrient broth medium. Results: Mean IZD of nano-formulations for all indicator bacteria were significantly higher than that of untreated AZI (P<0.01). The enhanced antibacterial efficacy was more dominant in the gram positive species. The MIC values of NPs against the tested bacteria were reduced 8 times in comparison to those of untreated AZI. Conclusion: These results indicated an improved potency of AZI NPs which could be attributed to the modified surface characteristics as well as increased drug adsorption and uptake.

Azhdarzadeh, Morteza; Lotfipour, Farzaneh; Zakeri-Milani, Parvin; Mohammadi, Ghobad; Valizadeh, Hadi

2012-01-01

134

In Vitro Antimicrobial Activities of Novel Anilinouracils Which Selectively Inhibit DNA Polymerase III of Gram-Positive Bacteria  

Microsoft Academic Search

The 6-anilinouracils are novel dGTP analogs that selectively inhibit the replication-specific DNA polymerase III of gram-positive eubacteria. Two specific derivatives, IMAU (6-(3*-iodo-4*-methylanilino)uracil) and EMAU (6-(3*-ethyl-4*-methylanilino)uracil), were substituted with either a hydroxybutyl (HB) or a methoxy- butyl (MB) group at their N3 positions to produce four agents: HB-EMAU, MB-EMAU, HB-IMAU, and MB-IMAU. These four new agents inhibited Staphylococcus aureus, coagulase-negative staphylococci,

JENNIFER S. DALY; THEODORE J. GIEHL; NEAL C. BROWN; CHENGXIN ZHI; GEORGE E. WRIGHT; RICHARD T. ELLISON III

2000-01-01

135

Rational Design of a Plasmid Origin That Replicates Efficiently in Both Gram-Positive and Gram-Negative Bacteria  

PubMed Central

Background Most plasmids replicate only within a particular genus or family. Methodology/Principal Findings Here we describe an engineered high copy number expression vector, pBAV1K-T5, that produces varying quantities of active reporter proteins in Escherichia coli, Acinetobacter baylyi ADP1, Agrobacterium tumefaciens, (all Gram-negative), Streptococcus pneumoniae, Leifsonia shinshuensis, Peanibacillus sp. S18-36 and Bacillus subtilis (Gram-positive). Conclusions/Significance Our results demonstrate the efficiency of pBAV1K-T5 replication in different bacterial species, thereby facilitating the study of proteins that don't fold well in E. coli and pathogens not amenable to existing genetic tools.

Bryksin, Anton V.; Matsumura, Ichiro

2010-01-01

136

The potent antimicrobial properties of cell penetrating peptide-conjugated silver nanoparticles with excellent selectivity for gram-positive bacteria over erythrocytes.  

PubMed

Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (gram-positive Bacillus subtilis, gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects. PMID:23525222

Liu, Lihong; Yang, Jun; Xie, Jianping; Luo, Zhentao; Jiang, Jiang; Yang, Yi Yan; Liu, Shaomin

2013-05-01

137

The Terminally Redundant, Nonpermuted Genome of Listeria Bacteriophage A511: a Model for the SPO1-Like Myoviruses of Gram-Positive Bacteria? †  

PubMed Central

Only little information on a particular class of myoviruses, the SPO1-like bacteriophages infecting low-G+C-content, gram-positive host bacteria (Firmicutes), is available. We present the genome analysis and molecular characterization of the large, virulent, broad-host-range Listeria phage A511. A511 contains a unit (informational) genome of 134,494 bp, encompassing 190 putative open reading frames (ORFs) and 16 tRNA genes, organized in a modular fashion common among the Caudovirales. Electron microscopy, enzymatic fragmentation analyses, and sequencing revealed that the A511 DNA molecule contains linear terminal repeats of a total of 3,125 bp, encompassing nine small putative ORFs. This particular genome structure explains why A511 is unable to perform general transduction. A511 features significant sequence homologies to Listeria phage P100 and other morphologically related phages infecting Firmicutes such as Staphylococcus phage K and Lactobacillus phage LP65. Equivalent but more-extensive terminal repeats also exist in phages P100 (?6 kb) and K (?20 kb). High-resolution electron microscopy revealed, for the first time, the presence of long tail fibers organized in a sixfold symmetry in these viruses. Mass spectrometry-based peptide fingerprinting permitted assignment of individual proteins to A511 structural components. On the basis of the data available for A511 and relatives, we propose that SPO1-like myoviruses are characterized by (i) their infection of gram-positive, low-G+C-content bacteria; (ii) a wide host range within the host bacterial genus and a strictly virulent lifestyle; (iii) similar morphology, sequence relatedness, and collinearity of the phage genome organization; and (iv) large double-stranded DNA genomes featuring nonpermuted terminal repeats of various sizes.

Klumpp, Jochen; Dorscht, Julia; Lurz, Rudi; Bielmann, Regula; Wieland, Matthias; Zimmer, Markus; Calendar, Richard; Loessner, Martin J.

2008-01-01

138

The terminally redundant, nonpermuted genome of Listeria bacteriophage A511: a model for the SPO1-like myoviruses of gram-positive bacteria.  

PubMed

Only little information on a particular class of myoviruses, the SPO1-like bacteriophages infecting low-G+C-content, gram-positive host bacteria (Firmicutes), is available. We present the genome analysis and molecular characterization of the large, virulent, broad-host-range Listeria phage A511. A511 contains a unit (informational) genome of 134,494 bp, encompassing 190 putative open reading frames (ORFs) and 16 tRNA genes, organized in a modular fashion common among the Caudovirales. Electron microscopy, enzymatic fragmentation analyses, and sequencing revealed that the A511 DNA molecule contains linear terminal repeats of a total of 3,125 bp, encompassing nine small putative ORFs. This particular genome structure explains why A511 is unable to perform general transduction. A511 features significant sequence homologies to Listeria phage P100 and other morphologically related phages infecting Firmicutes such as Staphylococcus phage K and Lactobacillus phage LP65. Equivalent but more-extensive terminal repeats also exist in phages P100 (approximately 6 kb) and K (approximately 20 kb). High-resolution electron microscopy revealed, for the first time, the presence of long tail fibers organized in a sixfold symmetry in these viruses. Mass spectrometry-based peptide fingerprinting permitted assignment of individual proteins to A511 structural components. On the basis of the data available for A511 and relatives, we propose that SPO1-like myoviruses are characterized by (i) their infection of gram-positive, low-G+C-content bacteria; (ii) a wide host range within the host bacterial genus and a strictly virulent lifestyle; (iii) similar morphology, sequence relatedness, and collinearity of the phage genome organization; and (iv) large double-stranded DNA genomes featuring nonpermuted terminal repeats of various sizes. PMID:18567664

Klumpp, Jochen; Dorscht, Julia; Lurz, Rudi; Bielmann, Regula; Wieland, Matthias; Zimmer, Markus; Calendar, Richard; Loessner, Martin J

2008-09-01

139

Biotransformation of 4-sec-butylphenol by Gram-positive bacteria of the genera Mycobacterium and Nocardia including modifications on the alkyl chain and the hydroxyl group.  

PubMed

The environmental pollutant 4-sec-butylphenol (4-sec-BP) which possesses estrogenic properties was transformed by the aerobic Gram-positive bacteria Mycobacterium neoaurum and Nocardia cyriacigeorgica into three main products (P1-P3) which were isolated and structurally characterized in detail. Two of them were products of a process resembling anaerobic metabolism of alkylphenols based on modifications of the alkyl side chain of 4-sec-BP. The first product (P1) was identified as 4-(2-hydroxy-1-methylpropyl)-phenol. The second product P2 was isolated as a mixture of at least four structures which could be identified as I 4-sec-butylidenecyclohexa-2,5-dienone; II 4-(1-methylenepropyl)-phenol; III 4-(1-methylpropenyl)-phenol; and IV 4-(1-methylallyl)-phenol. In contrast to P1 and P2, the third product (P3) resulted from a modification of the hydroxyl group of 4-sec-BP. This product was only formed by M. neoaurum and was identified as the glucoside conjugate 4-sec-butylphenol-?-D-glucopyranoside. Since in general, fungi synthesize sugar conjugates to detoxify hazardous pollutants, the formation of this conjugate is a peculiarity of M. neoaurum. Thus, altogether, six products were formed from 4-sec-BP and different transformation pathways are introduced. The hydroxylating and glucosylating capacity of the characterized bacteria open up applications in environmental protection. PMID:23912120

Hahn, Veronika; Sünwoldt, Katharina; Mikolasch, Annett; Schauer, Frieder

2013-09-01

140

Enhancement of Antibacterial Activity of Capped Silver Nanoparticles in Combination with Antibiotics, on Model Gram-Negative and Gram-Positive Bacteria  

PubMed Central

The nanoparticles used in this study were prepared from AgNO3 using NaBH4 in the presence of capping agents such as citrate, sodium dodecyl sulfate, and polyvinylpyrrolidone. The formed nanoparticles were characterized with UV-Vis, TEM, and XRD. The generation of silver nanoparticles was confirmed from the appearance of yellow colour and an absorption maximum between 399 and 404?nm. The produced nanoparticles were found to be spherical in shape and polydisperse. For citrate, SDS, and PVP capped nanoparticles, the average particle sizes were 38.3 ± 13.5, 19.3 ± 6.0, and 16.0 ± 4.8?nm, respectively. The crystallinity of the nanoparticles in FCC structure is confirmed from the SAED and XRD patterns. Also, the combined antibacterial activity of these differently capped nanoparticles with selected antibiotics (streptomycin, ampicillin, and tetracycline) was evaluated on model Gram-negative and Gram-positive bacteria, employing disc diffusion assay. The activity of the tested antibiotics was enhanced in combination with all the stabilized nanoparticles, against both the Gram classes of bacteria. The combined effects of silver nanoparticles and antibiotics were more prominent with PVP capped nanoparticles as compared to citrate and SDS capped ones. The results of this study demonstrate potential therapeutic applications of silver nanoparticles in combination with antibiotics.

Kora, Aruna Jyothi; Rastogi, Lori

2013-01-01

141

Phylogenetic analysis of Butyrivibrio strains reveals three distinct groups of species within the Clostridium subphylum of the gram-positive bacteria.  

PubMed

The phylogenetic positions of 40 Butyrivibrio strains were determined by performing a comparative sequence analysis of the 16S rRNA genes of these organisms. We found that all of the strains which we studied belong to cluster XIVa (M. D. Collins, P. A. Lawson, A. Willems, J. J. Cordoba, J. Fernandez=Garayzabal, P. Garcia, J. Cai, H. Hippe, and J. A. E. Farrow, Int. J. Syst. Bacteriol. 44:812-826, 1994) of the Clostridium subphylum of the gram-positive bacteria, which also includes several Clostridium, Coprococcus, Eubacterium, and Ruminococcus species. We also found that the Butyrivibrio strains which we examined were genotypically heterogeneous and exhibited 12 distinct rRNA sequence types. The 12 rRNA sequence types formed three distinct lineages in cluster XIVa, which were separate from each other and from all other species belonging to this cluster. One lineage consisted of strains which exhibited a single rRNA type and corresponded to the species Butyrivibrio crossotus. The second lineage consisted of 12 strains designated Butyrivibrio fibrisolvens which exhibited seven distinct rRNA sequence types. The type strain of B. fibrisolvens was a member of this lineage, but its position was peripheral. The third lineage comprised 26 B. fibrisolvens strains which exhibited four distinct rRNA sequence types. Tree topology and sequence divergence considerations indicated that the three lineages correspond to three separate genera and that the genus Butyrivibrio should be restricted to the group that contains the type strain of B. fibrisolvens. PMID:8573495

Willems, A; Amat-Marco, M; Collins, M D

1996-01-01

142

Interaction between the protein InlB of Listeria monocytogenes and lipoteichoic acid: a novel mechanism of protein association at the surface of gram-positive bacteria.  

PubMed

InlB is a Listeria monocytogenes protein that is sufficient to promote entry in a variety of mammalian cells. The last 232-amino-acid domain (Csa) of InlB has been shown to mediate attachment on the listerial surface, although its sequence does not suggest any known mechanism of association to the bacterial surface. InlB is present both on the bacterial surface and in culture supernatants. As has been recently demonstrated, both forms of InlB, soluble and surface-bound, can trigger signalling in host cells. To elucidate the specific role of each of the two forms, it was important to understand how InlB associates with the bacterial surface. Using microscopy, we find evidence that InlB is partially buried in the cell wall layer, and using fractionation experiments we demonstrate that InlB associates with the bacterial cytoplasmic membrane. Moreover, using purified lipoteichoic acid (LTA) and the three polypeptides InlB, Csa, or InlBDeltaCsa (InlB lacking the last 232 amino acids), we demonstrate that LTA is a ligand for the Csa domain of InlB. These results provide the first evidence of an interaction between lipoteichoic acids and a bacterial protein involved in adhesion and signalling, and highlight a new mechanism of protein association on the surface of Gram-positive bacteria. PMID:10594817

Jonquières, R; Bierne, H; Fiedler, F; Gounon, P; Cossart, P

1999-12-01

143

Computational identification of the Spo0A-phosphate regulon that is essential for the cellular differentiation and development in Gram-positive spore-forming bacteria  

PubMed Central

Spo0A-phosphate is essential for the initiation of cellular differentiation and developmental processes in Gram-positive spore-forming bacteria. Here we combined comparative genomics with analyses of microarray expression profiles to identify the Spo0A-phosphate regulon in Bacillus subtilis. The consensus Spo0A-phosphate DNA-binding motif identified from the training set based on different computational algorithms is an 8 bp sequence, TTGTCGAA. The same motif was identified by aligning the upstream regulatory sequences of spo0A-dependent genes obtained from the expression profile of Sad67 (a constitutively active form of Spo0A) and their orthologs. After the transcription units (TUs) having putative Spo0A-phosphate binding sites were obtained, conservation of regulons among the genomes of B.subtilis, Bacillus halodurans and Bacillus anthracis, and expression profiles were employed to identify the most confident predictions. Besides genes already known to be directly under the control of Spo0A-phosphate, 276 novel members (organized in 109 TUs) of the Spo0A-phosphate regulon in B.subtilis are predicted in this study. The sensitivity and specificity of our predictions are estimated based on known sites and combinations of different types of evidence. Further characterization of the novel candidates will provide information towards understanding the role of Spo0A-phosphate in the sporulation process, as well as the entire genetic network governing cellular differentiation and developmental processes in B.subtilis.

Liu, Jiajian; Tan, Kai; Stormo, Gary D.

2003-01-01

144

Identification of an endogenous membrane anchor-cleaving enzyme for group A streptococcal M protein. Its implication for the attachment of surface proteins in gram-positive bacteria  

PubMed Central

How streptococcal M protein or other surface proteins of gram-positive bacteria are anchored to the cell is poorly understood. Previously, we reported that M protein released after cell wall removal with a muralytic enzyme lacked the COOH terminal hydrophobic amino acids and charged tail predicted from DNA sequence. An endogenous membrane anchor- cleaving enzyme has now been identified with the ability to release M protein from isolated streptococcal protoplasts. At pH 5.5 in the presence of 30% raffinose, the streptococcal cell wall may be removed with a muralytic enzyme without releasing M protein from the resulting protoplasts indicating that the M molecule is attached through the bacterial cytoplasmic membrane. Release of M molecules occurs when the M protein-charged protoplasts are placed in raffinose buffer at pH 7.4. Although Zn2+, Cd2+, Ca2+, PHMB, and pHMPS inhibit the activity of the releasing enzyme, the blocking activity of Zn2+, Cd2+, and Ca2+ are reversible while PHMB and pHMPS are irreversible. PHMB-treated protoplasts are unable to release M protein at pH 7.4. However, M protein is liberated from these protoplasts when mixed with those prepared from M- streptococci serving as an enzyme source. The supernatant from M- protoplasts is unable to release M protein from PHMB-inactivated M+ protoplasts, confirming that the anchor-cleaving enzyme is membrane bound. Thus, the M protein releasing activity appears to be the result of a thiol-dependent anchor-cleaving enzyme. Streptococcal membranes treated with sodium carbonate and Triton X-114 still retain the M protein verifying that it is an integral membrane molecule. Evidence also is presented indicating significant sequence similarity between M protein and certain GPI-anchored proteins in the region responsible for protein anchoring.

1989-01-01

145

Integrated Physical and Genetic Mapping of Bacillus cereus and Other Gram-Positive Bacteria Based on IS231A Transposition Vectors  

PubMed Central

The genome structure of Bacillus cereus is relatively complex, its DNA being modulated between a size-varying chromosome and large plasmids. To study the genetic organization of the B. cereus type strain ATCC 14579, thermosensitive transposition vectors were designed on the basis of IS231A-derived cassettes containing uncommon restriction sites. A highly preferred insertion site for IS231A was detected in the chromosome by Southern blotting and pulsed-field gel electrophoresis (PFGE) analyses of independent insertion mutants. However, once this insertional hot spot was occupied, secondary IS231A insertions occurred randomly, as demonstrated by isolation of independent B. cereus auxotrophs at a frequency of approximately 0.6%. The hot-spot site, as well as several auxotrophic mutations, were mapped by using NotI, SfiI, and AscI PFGE restriction profiles. It was confirmed by sequencing that one of the insertions, generating an Ade? phenotype, had disrupted a gene of the purine synthesis pathway. These results showed that combined PFGE and sequencing analyses of mini-IS231A insertions enable the construction of integrated physical and genetic maps of B. cereus type strain. Moreover, the presence of the ultrarare I-SceI restriction site in the mini-IS231A allowed the isolation, in double-insertion mutants, of contiguous and nonoverlapping large chromosomal fragments, convenient for direct sequencing. The system detailed in this report is therefore a powerful tool for comparative genetic studies among members of the B. cereus group (i.e., B. cereus, B. thuringiensis, B. mycoides, and B. anthracis) and could also be applied to more distantly related gram-positive bacteria.

Leonard, Catherine; Zekri, Omar; Mahillon, Jacques

1998-01-01

146

3,5-dioxopyrazolidines, novel inhibitors of UDP-N- acetylenolpyruvylglucosamine reductase (MurB) with activity against gram-positive bacteria.  

PubMed

A series of 3,5-dioxopyrazolidines was identified as novel inhibitors of UDP-N-acetylenolpyruvylglucosamine reductase (MurB). Compounds 1 to 3, which are 1,2-bis(4-chlorophenyl)-3,5-dioxopyrazolidine-4-carboxamides, inhibited Escherichia coli MurB, Staphyloccocus aureus MurB, and E. coli MurA with 50% inhibitory concentrations (IC50s) in the range of 4.1 to 6.8 microM, 4.3 to 10.3 microM, and 6.8 to 29.4 microM, respectively. Compound 4, a C-4-unsubstituted 1,2-bis(3,4-dichlorophenyl)-3,5-dioxopyrazolidine, showed moderate inhibitory activity against E. coli MurB, S. aureus MurB, and E. coli MurC (IC50s, 24.5 to 35 microM). A fluorescence-binding assay indicated tight binding of compound 3 with E. coli MurB, giving a dissociation constant of 260 nM. Structural characterization of E. coli MurB was undertaken, and the crystal structure of a complex with compound 4 was obtained at 2.4 A resolution. The crystal structure indicated the binding of a compound at the active site of MurB and specific interactions with active-site residues and the bound flavin adenine dinucleotide cofactor. Peptidoglycan biosynthesis studies using a strain of Staphylococcus epidermidis revealed reduced peptidoglycan biosynthesis upon incubation with 3,5-dioxopyrazolidines, with IC50s of 0.39 to 11.1 microM. Antibacterial activity was observed for compounds 1 to 3 (MICs, 0.25 to 16 microg/ml) and 4 (MICs, 4 to 8 microg/ml) against gram-positive bacteria including methicillin-resistant S. aureus, vancomycin-resistant Enterococcus faecalis, and penicillin-resistant Streptococcus pneumoniae. PMID:16436710

Yang, Youjun; Severin, Anatoly; Chopra, Rajiv; Krishnamurthy, Girija; Singh, Guy; Hu, William; Keeney, David; Svenson, Kristine; Petersen, Peter J; Labthavikul, Pornpen; Shlaes, David M; Rasmussen, Beth A; Failli, Amedeo A; Shumsky, Jay S; Kutterer, Kristina M K; Gilbert, Adam; Mansour, Tarek S

2006-02-01

147

Identification of a new family of enzymes with potential O-acetylpeptidoglycan esterase activity in both Gram-positive and Gram-negative bacteria  

PubMed Central

Background The metabolism of the rigid bacterial cell wall heteropolymer peptidoglycan is a dynamic process requiring continuous biosynthesis and maintenance involving the coordination of both lytic and synthetic enzymes. The O-acetylation of peptidoglycan has been proposed to provide one level of control on these activities as this modification inhibits the action of the major endogenous lytic enzymes, the lytic transglycosylases. The O-acetylation of peptidoglycan also inhibits the activity of the lysozymes which serve as the first line of defense of host cells against the invasion of bacterial pathogens. Despite this central importance, there is a dearth of information regarding peptidoglycan O-acetylation and nothing has previously been reported on its de-acetylation. Results Homology searches of the genome databases have permitted this first report on the identification of a potential family of O-Acetylpeptidoglycan esterases (Ape). These proteins encoded in the genomes of a variety of both Gram-negative and Gram-positive bacteria, including a number of important human pathogens such as species of Neisseria, Helicobacter, Campylobacter, and Bacillus anthracis, have been organized into three families based on amino acid sequence similarities with family 1 being further divided into three sub-families. The genes encoding these proteins are shown to be clustered with Peptidoglycan O-acetyltransferases (Pat) and in some cases, together with other genes involved in cell wall metabolism. Representative bacteria that encode the Ape proteins were experimentally shown to produce O-acetylated peptidoglycan. Conclusion The hypothetical proteins encoded by the pat and ape genes have been organized into families based on sequence similarities. The Pat proteins have sequence similarity to Pseudomonas aeruginosa AlgI, an integral membrane protein known to participate in the O-acetylation of the exopolysaccaride, alginate. As none of the bacteria that harbor the pat genes produce alginate, we propose that the Pat proteins serve to O-acetylate peptidoglycan which is known to be a maturation event occurring in the periplasm. The Ape sequences have amino acid sequence similarity to the CAZy CE 3 carbohydrate esterases, a family previously known to be composed of only O-acetylxylan esterases. They are predicted to contain the ?/? hydrolase fold associated with the GDSL and TesA hydrolases and they possess the signature motifs associated with the catalytic residues of the CE3 esterases. Specific signature sequence motifs were identified for the Ape proteins which led to their organization into distinct families. We propose that by expressing both Pat and Ape enzymes, bacteria would be able to obtain a high level of localized control over the degradation of peptidoglycan through the attachment and removal of O-linked acetate. This would facilitate the efficient insertion of pores and flagella, localize spore formation, and control the level of general peptidoglycan turnover.

Weadge, Joel T; Pfeffer, John M; Clarke, Anthony J

2005-01-01

148

Lagging strand replication of rolling-circle plasmids: Specific recognition of the ssoA-type origins in different gram-positive bacteria  

PubMed Central

Many bacterial plasmids replicate by a rolling-circle mechanism that involves the generation of single-stranded DNA (ssDNA) intermediates. Replication of the lagging strand of such plasmids initiates from their single strand origin (sso). Many different types of ssos have been identified. One group of ssos, termed ssoA, which have conserved sequence and structural features, function efficiently only in their natural hosts in vivo. To study the host specificity of sso sequences, we have analyzed the functions of two closely related ssoAs belonging to the staphylococcal plasmid pE194 and the streptococcal plasmid pLS1 in Staphylococcus aureus. The pLS1 ssoA functioned poorly in vivo in S. aureus as evidenced by accumulation of high levels of ssDNA but supported efficient replication in vitro in staphylococcal extracts. These results suggest that one or more host factors that are present in sufficient quantities in S. aureus cell-free extracts may be limiting in vivo. Mapping of the initiation points of lagging strand synthesis in vivo and in vitro showed that DNA synthesis initiates from specific sites within the pLS1 ssoA. These results demonstrate that specific initiation of replication can occur from the pLS1 ssoA in S. aureus although it plays a minimal role in lagging strand synthesis in vivo. Therefore, the poor functionality of the pLS1 in vivo in a nonnative host is caused by the low efficiency rather than a lack of specificity of the initiation process. We also have identified ssDNA promoters and mapped the primer RNAs synthesized by the S. aureus and Bacillus subtilis RNA polymerases from the pE194 and pLS1 ssoAs. The S. aureus RNA polymerase bound more efficiently to the native pE194 ssoA as compared with the pLS1 ssoA, suggesting that the strength of RNA polymerase–ssoA interaction may play a major role in the functionality of the ssoA sequences in Gram-positive bacteria.

Kramer, M. Gabriela; Espinosa, Manuel; Misra, Tapan K.; Khan, Saleem A.

1998-01-01

149

Evidence for the placement of the gram-negative Catonella morbi (Moore and Moore) and Johnsonella ignava (Moore and Moore) within the Clostridium subphylum of the gram-positive bacteria on the basis of 16S rRNA sequences.  

PubMed

Comparative 16S rRNA analysis was used to determine the phylogenetic positions of Catonella morbi and Johnsonella ignava, which are members of two monospecific genera of gram-negative anaerobic bacilli isolated from human gingival crevices. Both of these genera were found to belong to cluster XIVa (M. D. Collins, P. A. Lawson, A. Willems, J. J. Cordoba, J. Fernandez-Garayzabal, P. Garcia, J. Cai, H. Hippe, and J. A. E. Farrow, Int. J. Syst. Bacteriol. 44:812-826, 1994) of the Clostridium subphylum of gram-positive bacteria. Within this cluster, which contains several Clostridium, Coprococcus, Eubacterium, and Ruminococcus species, C. morbi and J. ignava formed two distinct lines that were separate from all other taxa. Our findings support the separate generic status of the genera Catonella and Johnsonella and show that these genera do not belong to the family Bacteroidaceae but instead belong to the gram-positive Clostridium subphylum. PMID:7547310

Willems, A; Collins, M D

1995-10-01

150

Real-Time PCR quantification of PAH-ring hydroxylating dioxygenase (PAH-RHD ?) genes from Gram positive and Gram negative bacteria in soil and sediment samples  

Microsoft Academic Search

Real-Time PCR based assays were developed to quantify Gram positive (GP) and Gram negative (GN) bacterial populations that are capable of degrading the polycyclic aromatic hydrocarbons (PAH) in soil and sediment samples with contrasting contamination levels. These specific and sensitive Real-Time PCR assays were based on the quantification of the copy number of the gene that encodes the alpha subunit

Aurélie Cébron; Marie-Paule Norini; Thierry Beguiristain; Corinne Leyval

2008-01-01

151

Role of Intestinal Epithelial Cells in Immune Effects Mediated by Gram-Positive Probiotic Bacteria: Involvement of Toll-Like Receptors  

PubMed Central

The mechanisms by which probiotic bacteria exert their effects on the immune system are not completely understood, but the epithelium may be a crucial player in the orchestration of the effects induced. In a previous work, we observed that some orally administered strains of lactic acid bacteria (LAB) increased the number of immunoglobulin A (IgA)-producing cells in the small intestine without a concomitant increase in the CD4+ T-cell population, indicating that some LAB strains induce clonal expansion only of B cells triggered to produce IgA. The present work aimed to study the cytokines induced by the interaction of probiotic LAB with murine intestinal epithelial cells (IEC) in healthy animals. We focused our investigation mainly on the secretion of interleukin 6 (IL-6) necessary for the clonal expansion of B cells previously observed with probiotic bacteria. The role of Toll-like receptors (TLRs) in such interaction was also addressed. The cytokines released by primary cultures of IEC in animals fed with Lactobacillus casei CRL 431 or Lactobacillus helveticus R389 were determined. Cytokines were also determined in the supernatants of primary cultures of IEC of unfed animals challenged with different concentrations of viable or nonviable lactobacilli and Escherichia coli, previously blocked or not with anti-TLR2 and anti-TLR4. We concluded that the small intestine is the place where a major distinction would occur between probiotic LAB and pathogens. This distinction comprises the type of cytokines released and the magnitude of the response, cutting across the line that separates IL-6 necessary for B-cell differentiation, which was the case with probiotic lactobacilli, from inflammatory levels of IL-6 for pathogens.

Vinderola, Gabriel; Matar, Chantal; Perdigon, Gabriela

2005-01-01

152

[MRSA/MRSE-VISA/GISA/VRSA-PRP-VRE: current gram positive problem bacteria and mechanism of resistance, prevalence and clinical consequences].  

PubMed

The raising frequency of occurrence of multi-resistant Gram-positive pathogens has led to difficult to treat infections not only in hospitals but also in outpatient settings. Methicillin-resistant Staphylococcus aureus, the glycopeptide-susceptibility of which one cannot be sure of any more, vancomycin-resistant enterococci and penicillin-resistant pneumococci are on the top of the list of Gram-positive problem organisms nowadays. Clinical microbiology laboratories are faced with the challenge of accurately detecting emerging antibiotic resistance, which might be difficult and purpose of reporting data should be twofold: First to report adequately identified, relevant organisms as well as their susceptibility profiles to clinicians in context with adequate patient management and secondly to report continuously epidemiological data in form of statistics to the community in general and within a given setting as could be a specified hospital in particular. For reliable detection, laboratories may need to employ special screening- and susceptibility testing methods. Certain of these tests are highly specific, while others may require additional confirmatory testing for definite results. This article reports on current resistance mechanisms of gram-positive pathogens and subsequently resulting consequences for clinicians. Moreover, the frequency of occurrence in Austria in general as well as at the Vienna General Hospital in particular will be referred to. PMID:12764866

Apfalter, Petra

2003-01-01

153

Heavy metal resistance and genotypic analysis of metal resistance genes in gram-positive and gram-negative bacteria present in Ni-rich serpentine soil and in the rhizosphere of Alyssum murale.  

PubMed

Forty-six bacterial cultures, including one culture collection strain, thirty from the rhizosphere of Alyssum murale and fifteen from Ni-rich soil, were tested for their ability to tolerate arsenate, cadmium, chromium, zinc, mercury, lead, cobalt, copper, and nickel in their growth medium. The resistance patterns, expressed as minimum inhibitory concentrations, for all cultures to the nine different metal ions were surveyed by using the agar dilution method. A large number of the cultures were resistant to Ni (100%), Pb (100%), Zn (100%), Cu (98%), and Co (93%). However, 82, 71, 58 and 47% were sensitive to As, Hg, Cd and Cr(VI), respectively. All cultures had multiple metal-resistant, with heptametal resistance as the major pattern (28.8%). Five of the cultures (about of 11.2% of the total), specifically Arthrobacter rhombi AY509239, Clavibacter xyli AY509235, Microbacterium arabinogalactanolyticum AY509226, Rhizobium mongolense AY509209 and Variovorax paradoxus AY512828 were tolerant to nine different metals. The polymerase chain reaction in combination with DNA sequence analysis was used to investigate the genetic mechanism responsible for the metal resistance in some of these gram-positive and gram-negative bacteria that were, highly resistant to Hg, Zn, Cr and Ni. The czc, chr, ncc and mer genes that are responsible for resistance to Zn, Cr, Ni and Hg, respectively, were shown to be present in these bacteria by using PCR. In the case of, M. arabinogalactanolyticum AY509226 these genes were shown to have high homology to the czcD, chrB, nccA, and mer genes of Ralstonia metallidurans CH34. Therefore, Hg, Zn, Cr and Ni resistance genes are widely distributed in both gram-positive and gram-negative isolates obtained from A. murale rhizosphere and Ni-rich soils. PMID:17276484

Abou-Shanab, R A I; van Berkum, P; Angle, J S

2007-06-01

154

[The characteristics of Gram-positive bacteria isolated from skin lesions observed in ambulatory patients and the assessment of their susceptibility to antimicrobial drugs].  

PubMed

The bacterial skin and soft-tissue infections occur commonly and are characterized by more or less intensified changes within skin and subcutaneous tissue. The bacterial skin infections give rise to significant therapeutic problems associated with increasing resistance etiological agents of these infections to antibiotics and chemotherapeutics. The aim of this study was to assess the distribution of various Gram-positive microorganisms in skin lesion observed in ambulatory patients in a period from June 2005 to December 2006. There were 116 bacterial strains isolated and identified from clinical samples: Staphylococcus aureus, coagulase - negative staphylococi (S.epidermidis, S. xylosus, S.capitis, S.saccharolyticus), Propionobacterium acnes, Streptococcus spp. (S.agalactiae, S.pyogenes) i Corynebacterium spp. (C. striatum, C. amycolatum, C. aquaticum). In the further part of this study we analyzed a profile of their susceptibility to antibiotics and chemotherapeutics in relation to drugs recommended for the empirical therapy. The resultant resistance patterns among the examined bacterial isolates are indicative of certain divergence between recommended empirical antibiotic therapy and actual antimicrobial susceptibility of many etiologic factors of skin and soft-tissue infections. PMID:21853673

Sikora, Agnieszka; Kozio?-Montewka, Maria; Bogut, Agnieszka

2011-01-01

155

The affect of low-coherent light on microbial colony forming ability and morphology of some gram-positive and gram-negative bacteria  

NASA Astrophysics Data System (ADS)

Gram-negative E. coli, gram-positive facultative anaerobe cocci Staphylococcus lugdensis, Micrococcus halobius, and Stomatococcus mucilaginosus as subjects of study were chosen. LEDs with spectrum maxima at 405 nm (without any exogenous sensitizer) and 660 nm (in conjunction with methylene blue) and power densities of 23 mW/cm2 and 5.7 mW/cm2 accordingly as continuous light sources were chosen. Photosensitized light's affect by methylene blue was studied on E. coli only. The original scheme of experiment set up was developed. It permits one to increase expositions quantity in each experiment for more certain trend's construction over dose curves and decrease parasite flora sowing. As a result of accomplished studies it was established that blue low-coherent light have unalike weak light's dose depending suppressing effect on cocci whereas red low-coherent light have a moderate dose-depended suppressing effect at low irradiation doses and a moderate dose-depended stimulating effect at high irradiation doses on sensitized by MeBlue E. coli. For all ofthis, but Staphylococcus morphology changes were observed.

Popov, Denis E.; Tuchina, Elena S.; Chernova, Julia A.; Podshibyakin, Dmitry; Rudik, Dmitry V.; Samsonova, Maria; Gromov, Igor; Tuchin, Valery V.

2005-06-01

156

Pharmacodynamics of TD-1792, a novel glycopeptide-cephalosporin heterodimer antibiotic used against Gram-positive bacteria, in a neutropenic murine thigh model.  

PubMed

TD-1792 is a novel glycopeptide-cephalosporin heterodimer investigational antibiotic that displays potent bactericidal effects against clinically relevant Gram-positive organisms in vitro. The present studies evaluated the in vivo pharmacokinetics (PK) and pharmacodynamics (PD) of TD-1792 in the neutropenic murine thigh infection animal model. TD-1792, dosed subcutaneously (SC), produced dose-dependent reduction in the thigh bacterial burden of several organisms, including methicillin-susceptible and -resistant strains of Staphylococcus aureus and Staphylococcus epidermidis (MSSA, MRSA, MSSE, MRSE, respectively), penicillin-susceptible strains of Streptococcus pneumoniae (PSSP), Streptococcus pyogenes, and vancomycin-intermediate-susceptible Staphylococcus aureus (VISA). In single-dose efficacy studies, the 1-log(10) CFU kill effective dose (ED(1-log kill)) estimates for TD-1792 ranged from 0.049 to 2.55 mg/kg of body weight administered SC, and the bacterial burden was reduced by up to 3 log(10) CFU/g from pretreatment values. Against S. aureus ATCC 33591 (MRSA), the total 24-h log(10) stasis dose (ED(stasis)) and ED(1-logkill) doses for TD-1792 were 0.53 and 1.11 mg/kg/24 h, respectively, compared to 23.4 and 54.6 mg/kg/24 h for vancomycin, indicating that TD-1762 is 44- to 49-fold more potent than vancomycin. PK-PD analysis of data from single-dose and dose-fractionation studies for MRSA (ATCC 33591) demonstrated that the total-drug 24-h area under the concentration-time curve-to-MIC ratio (AUC/MIC ratio) was the best predictor of efficacy (r(2) = 0.826) compared to total-drug maximum plasma concentration of drug-to-MIC ratio (Cmax/MIC ratio; r(2) = 0.715) and percent time that the total-drug plasma drug concentration remains above the MIC (%Time>MIC; r(2) = 0.749). The magnitudes of the total-drug AUC/MIC ratios associated with net bacterial stasis, a 1-log(10) CFU reduction from baseline and near maximal effect, were 21.1, 37.2, and 51.8, respectively. PK-PD targets based on such data represent useful inputs for analyses to support dose selection decisions for clinical studies of patients. PMID:22155835

Hegde, Sharath S; Okusanya, Olanrewaju O; Skinner, Robert; Shaw, Jeng-Pyng; Obedencio, Glenmar; Ambrose, Paul G; Blais, Johanne; Bhavnani, Sujata M

2012-03-01

157

The Recombination Genes addAB Are Not Restricted to Gram-Positive Bacteria: Genetic Analysis of the Recombination Initiation Enzymes RecF and AddAB in Rhizobium etli  

PubMed Central

Single-strand gaps (SSGs) and double-strand breaks (DSBs) are the major initiation sites for recombination. In bacteria, the SSGs are repaired by RecFOR, while the DSBs are processed by RecBCD in gram-negative bacteria and AddAB in gram-positive bacteria. Unexpectedly, instead of recBCD genes, the addAB genes were found in members of the ?-proteobacteria group (gram negative). Taking Rhizobium etli as a model, the role of recF and addAB genes in homologous recombination and repair of damaged DNA was evaluated. Inactivation of either recF or addA provoked strong sensitivity to UV radiation and mitomycin C, while an additive effect was observed in the recF-addA mutant. The DSBs generated by nalidixic acid caused low viability only in the addA mutant. The recombination frequency of large and small plasmids was reduced in the recF mutant (24- and 36-fold, respectively), whereas a slight decrease (threefold) in the addA mutant was observed. Moreover, an additive effect (47- and 90-fold, respectively) was observed in the double mutant, but it was not as dramatic as that in a recA mutant. Interestingly, the frequency of deletion and Campbell-type recombination was slightly affected in either single or double mutants. These results suggest that another pathway exists that allows plasmid and Campbell-type recombination in the absence of recF and addA genes.

Zuniga-Castillo, Jacobo; Romero, David; Martinez-Salazar, Jaime M.

2004-01-01

158

Mechanism of copper surface toxicity in Escherichia coli O157:H7 and Salmonella involves immediate membrane depolarization followed by slower rate of DNA destruction which differs from that observed for Gram-positive bacteria.  

PubMed

We have reported previously that copper I and II ionic species, and superoxide but not Fenton reaction generated hydroxyl radicals, are important in the killing mechanism of pathogenic enterococci on copper surfaces. In this new work we determined if the mechanism was the same in non-pathogenic ancestral (K12) and laboratory (DH5?) strains, and a pathogenic strain (O157), of Escherichia coli. The pathogenic strain exhibited prolonged survival on stainless steel surfaces compared with the other E.?coli strains but all died within 10?min on copper surfaces using a 'dry' inoculum protocol (with approximately 10(7) ?cfu?cm(-2) ) to mimic dry touch contamination. We observed immediate cytoplasmic membrane depolarization, not seen with enterococci or methicillin resistant Staphylococcus aureus, and loss of outer membrane integrity, inhibition of respiration and in situ generation of reactive oxygen species on copper and copper alloy surfaces that did not occur on stainless steel. Chelation of copper (I) and (II) ionic species still had the most significant impact on bacterial survival but protection by d-mannitol suggests hydroxyl radicals are involved in the killing mechanism. We also observed a much slower rate of DNA destruction on copper surfaces compared with previous results for enterococci. This may be due to protection of the nucleic acid by the periplasm and the extensive cell aggregation that we observed on copper surfaces. Similar results were obtained for Salmonella species but partial quenching by d-mannitol suggests radicals other than hydroxyl may be involved. The results indicate that copper biocidal surfaces are effective for Gram-positive and Gram-negative bacteria but bacterial morphology affects the mechanism of toxicity. These surfaces could not only help to prevent infection spread but also prevent horizontal gene transmission which is responsible for the evolution of virulent toxin producing and antibiotic resistant bacteria. PMID:22176893

Warnes, S L; Caves, V; Keevil, C W

2012-07-01

159

Genomics of Probiotic Bacteria  

NASA Astrophysics Data System (ADS)

Probiotic bacteria from the Lactobacillus and Bifidobacterium species belong to the Firmicutes and the Actinobacteria phylum, respectively. Lactobacilli are members of the lactic acid bacteria (LAB) group, a broadly defined family of microorganisms that ferment various hexoses into primarily lactic acid. Lactobacilli are typically low G + C gram-positive species which are phylogenetically diverse, with over 100 species documented to date. Bifidobacteria are heterofermentative, high G + C content bacteria with about 30 species of bifidobacteria described to date.

O'Flaherty, Sarah; Goh, Yong Jun; Klaenhammer, Todd R.

160

Ligand-exchangeability of 2-coordinate phosphinegold(I) complexes with AuSP and AuNP cores showing selective antimicrobial activities against Gram-positive bacteria. Crystal structures of [Au(2-Hmpa)(PPh 3)] and [Au(6-Hmna)(PPh 3)] (2-H 2mpa=2-mercaptopropionic acid, 6-H 2mna=6-mercaptonicotinic acid)  

Microsoft Academic Search

Selective and effective antimicrobial activities against Gram-positive bacteria (B. subtilis and\\/or S. aureus) were found in 2-coordinate gold(I)–PPh3 complexes with AuSP and AuNP cores, i.e. [Au(L)(PPh3)] (HL=2-H2mna [H2mna=mercaptonicotinic acid] 3, d-H2pen [H2pen=penicillamine] 4, d,l-H2pen 5, 4-H2mba [H2mba=mercaptobenzoic acid] 8, Hpz [Hpz=pyrazole] 9, Him [Him=imidazole] 10, 1,2,3-Htriz [Htriz=triazole] 11, 1,2,4-Htriz 12, Htetz [Htetz=tetrazole] 13), whereas no activity was observed in 2-coordinate

Kenji Nomiya; Satoshi Yamamoto; Ryusuke Noguchi; Hironari Yokoyama; Noriko Chikaraishi Kasuga; Kei Ohyama; Chieko Kato

2003-01-01

161

Development of an Organ Culture System for the Study of an Invasive Gram Positive Organism Infecting Bullfrogs, 'Rana catesbeiana'.  

National Technical Information Service (NTIS)

Recent observations on frogs afflicted with red-leg disease indicate that the clinically important bacteria associated with this disease include 13 gram negative bacteria and one gram positive bacterium. Attempts to study the role of the gram positive iso...

R. L. Amborski J. C. Glorioso G. F. Amborski

1974-01-01

162

Ethanol production in Gram-positive microbes  

DOEpatents

The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase. 2 figs.

Ingram, L.O.; Barbosa-Alleyne, M.D.F.

1999-06-29

163

Peptidoglycan turnover and recycling in Gram-positive bacteria  

Microsoft Academic Search

Bacterial cells are protected by an exoskeleton, the stabilizing and shape-maintaining cell wall, consisting of the complex\\u000a macromolecule peptidoglycan. In view of its function, it could be assumed that the cell wall is a static structure. In truth,\\u000a however, it is steadily broken down by peptidoglycan-cleaving enzymes during cell growth. In this process, named cell wall\\u000a turnover, in one generation

Jan Reith; Christoph Mayer

164

Anaerobic bacteria  

MedlinePLUS

Anaerobic bacteria are bacteria that do not live or grow in the presence of oxygen. In humans, ... Goldstein EJ. Diseases caused by non-spore forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman's ...

165

Moderately halophilic gram-positive bacterial diversity in hypersaline environments  

Microsoft Academic Search

Moderately halophilic bacteria are microorganisms that grow optimally in media containing 3%–15% (w\\/v) salt. They are represented\\u000a by a heterogeneous group of microorganisms included in many different genera. Gram-negative moderately halophilic bacteria\\u000a have been studied in more detail, but studies on gram-positive species are more scarce. Recent studies carried out by our\\u000a research group on gram-positive moderate halophiles have permitted

Antonio Ventosa; M. Carmen Márquez; María J. Garabito; David R. Arahal

1998-01-01

166

Display of proteins on bacteria  

Microsoft Academic Search

Display of heterologous proteins on the surface of microorganisms, enabled by means of recombinant DNA technology, has become an increasingly used strategy in various applications in microbiology, biotechnology and vaccinology. Gram-negative, Gram-positive bacteria, viruses and phages are all being investigated in such applications. This review will focus on the bacterial display systems and applications. Live bacterial vaccine delivery vehicles are

Patrik Samuelson; Elin Gunneriusson; Per-Åke Nygren; Stefan Ståhl

2002-01-01

167

Lactic Acid Bacteria in the Gut  

Microsoft Academic Search

From all bacterial groups, the lactic acid bacteria (LAB) are probably the group of bacteria that is most associated with human lifestyle. The term LAB mainly refers to the ability of these organisms to convert sugars to lactic acid. The LAB comprise non-sporing, aerotolerant, coccus or rod-shaped, gram-positive, polyphyletic bacteria. The vast majority of the LAB belong to the phylum

M. Stolaki; Vos de W. M; M. Kleerebezem; E. G. Zoetendal

2012-01-01

168

Antimicrobial activity of lactic acid bacteria isolated from minced beef meat against some pathogenic bacteria  

Microsoft Academic Search

In this study we achieved to isolate and identify Lactic Acid Bacteria (LAB) from minced beef meat by using de Man Rogosa and Sharpe agar (MRS) medium. The influence of antimicrobial activities were obtained by using the agar well diffusion method (Muller Hinton Agar) against some members of gram positive and gram negative pathogenic bacteria involved ( Escherichia coli, Pseudomonas

M. A. H. Al-Allaf; A. M. M. Al-Rawi; A. T. Al-Mola

169

Bacteria bites  

NASA Astrophysics Data System (ADS)

Naturally occurring bacteria may be a future solution for myriad pollution problems, mounting laboratory evidence suggests. Last month, USGS scientists reported in Nature that microbes living in oxygen-free sediments can break down derivatives of hydrofluorocarbons, which are among the compounds under consideration to replace ozone-destroying chlorofluorocarbons (CFCs). And now, another USGS scientist reports in the July 14 Nature that microbes which degrade toxic and carcinogenic aromatic hydrocarbons like benzene and toluene can be boosted with an iron additive or chemical binder to work in anaerobic conditions that are commonly found in heavily polluted aquifers. Previously, scientists thought the bacteria could reduce the hard pollutants only if plenty of dissolved oxygen was in the water. Other bacteria have been shown to convert uranium to a highly insoluble form in cbntaminated waters as well.

170

Growth of bacteria in blood  

PubMed Central

It has been demonstrated experimentally that small numbers of a variety of different bacteria fail to survive or multiply in normal cow or human blood or in a mixture of blood and a suitable culture medium, owing to the binding of the magnesium ion and a protein component of the antimicrobial system. However, a satisfactory and simple method has now been evolved for the rapid multiplication of Gram-negative and Gram-positive bacteria in blood without the addition of a liquid culture medium. This method involves the addition to blood of optimum amounts of hydrogen and magnesium ion exchange resins and sodium citrate.

Huddleson, I. Forest

1959-01-01

171

Clinical microbiology of coryneform bacteria.  

PubMed Central

Coryneform bacteria are aerobically growing, asporogenous, non-partially-acid-fast, gram-positive rods of irregular morphology. Within the last few years, there has been a massive increase in the number of publications related to all aspects of their clinical microbiology. Clinical microbiologists are often confronted with making identifications within this heterogeneous group as well as with considerations of the clinical significance of such isolates. This review provides comprehensive information on the identification of coryneform bacteria and outlines recent changes in taxonomy. The following genera are covered: Corynebacterium, Turicella, Arthrobacter, Brevibacterium, Dermabacter. Propionibacterium, Rothia, Exiguobacterium, Oerskovia, Cellulomonas, Sanguibacter, Microbacterium, Aureobacterium, "Corynebacterium aquaticum," Arcanobacterium, and Actinomyces. Case reports claiming disease associations of coryneform bacteria are critically reviewed. Minimal microbiological requirements for publications on disease associations of coryneform bacteria are proposed.

Funke, G; von Graevenitz, A; Clarridge, J E; Bernard, K A

1997-01-01

172

Bacteria Counter  

NASA Technical Reports Server (NTRS)

Science Applications, Inc.'s ATP Photometer makes a rapid and accurate count of the bacteria in a body fluid sample. Instrument provides information on the presence and quantity of bacteria by measuring the amount of light emitted by the reaction between two substances. Substances are ATP adenosine triphosphate and luciferase. The reactants are applied to a human body sample and the ATP Photometer observes the intensity of the light emitted displaying its findings in a numerical output. Total time lapse is usually less than 10 minutes, which represents a significant time savings in comparison of other techniques. Other applications are measuring organisms in fresh and ocean waters, determining bacterial contamination of foodstuffs, biological process control in the beverage industry, and in assay of activated sewage sludge.

1981-01-01

173

Review: Bacteriocins of Lactic Acid Bacteria  

Microsoft Academic Search

During the last few years, a large number of new bacteriocins produced by lactic acid bacteria (LAB) have been identified and characterized. LAB-bacteriocins comprise a heterogeneous group of physicochemically diverse ribosomally-synthesized peptides or proteins showing a narrow or broad antimicrobial activity spectrum against Gram-positive bacteria. Bacteriocins are classified into separate groups such as the lantibiotics (Class I); the small (<10

L. M. Cintas; M. P. Casaus; C. Herranz; I. F. Nes; P. E. Hernández

2001-01-01

174

Proposals Concerning the Higher Taxa of Bacteria  

Microsoft Academic Search

Names are proposed for divisions, classes, and some orders of bacteria. The kingdom Procaryotae Murray 1968 is divided into three divisions: Gracilicutes divisio nov., Firmacutes divisio nov., and Mollicutes Edward and Freundt 1967, for organisms having, respectively, a gram-negative cell wall, a gram-positive cell wall, and no cell wall. Gracilicutes comprises the class Photobacteria classis nov. for organisms having a

N. E. GIBBONSt; R. G. E. MURRAY

1978-01-01

175

Keratinolytic bacteria isolated from feather waste  

Microsoft Academic Search

The aim of this study was to characterize keratinolytic bacteria isolated from feather waste. Four isolates were selected after growth on solid medium with feather meal as sole carbon and nitrogen source and screened for proteolytic activity on milk agar plates. Three isolates were Gram-negative (belonged to the genera Burkholderia, Chryseobacterium and Pseudomonas) and one was Gram-positive (Microbacterium sp.). These

Alessandro Riffel; Adriano Brandelli

2006-01-01

176

Mechanisms of action of newer antibiotics for Gram-positive pathogens.  

PubMed

Certain Gram-positive bacteria, including meticillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and quinolone-resistant Streptococcus pneumoniae have achieved the status of "superbugs", in that there are few or no antibiotics available for therapy against these pathogens. Only a few classes of novel antibiotics have been introduced in the past 40 years, and all since 1999, including the streptogramin combination quinupristin/dalfopristin (Synercid), the oxazolidinone linezolid, and the lipopeptide daptomycin. This review discusses the mechanisms of antibiotic action against Gram-positive pathogens, and resistance counter-mechanisms developed by Gram-positive bacteria, with emphasis on the newer agents. PMID:15792738

Hancock, Robert Ew

2005-04-01

177

Isolation, Characterization and Identification of Bacteria associated with Mucus of Acropora cervicornis Coral from Bidong Island, Terengganu, Malaysia  

Microsoft Academic Search

Marine bacteria associated with mucus of Acropora cervicornis coral of Bidong Island were successfully isolated and cultured on sucrose sea water agar (SSW). The bacteria were characterized by using selective culture media and biochemical assays. Four major groups of bacteria were obtained, ?- proteobacteria, ?-proteobacteria, high G+C gram positive bacteria, CFB group and unknowns. The coral mucus-associated bacteria strains were

Murugan Kalimutho; Aziz Ahmad; Zaleha Kassim

2007-01-01

178

Evaluation of a fluorescent lectin-based staining technique for some acidophilic mining bacteria  

SciTech Connect

A fluorescence-labeled wheat germ agglutinin staining technique was modified and found to be effective for staining gram-positive, acidophilic mining bacteria. Bacteria identified by others as being gram positive through 16S rRNA sequence analyses, yet clustering near the divergence of that group, stained weakly. Gram-negative bacteria did not stain. Background staining of environmental samples was negligible, and pyrite and soil particles in the samples did not interfere with the staining procedure.

Fife, D.J.; Bruhn, D.F.; Miller, K.S.; Stoner, D.L.

2000-05-01

179

Special features of gram-positive bacterial eradication by photosensitizers.  

PubMed

Antibiotic resistance of pathogenic bacteria is a major concern and presents a special challenge for development of alternative antibacterial modalities. One of these alternative approaches is based on using the photodynamic therapy (PDT) for eradicating bacteria. Photosensitizer-induced PDT exhibits unique properties and demonstrates efficient microbe-killing effects. The efficient and irreversible antimicrobial effects of PDT are not dependent on the antibiotic susceptibility of the pathogenic bacteria to antibiotics. Gram-positive bacteria exhibit efficient binding of the photosensitizer to the bacterial barriers, leading to immediate photoinactivation of the bacteria. Photoinactivation of Gram-positive bacteria by various photosensitizers has become a high priority, since these bacteria are responsible for life-threatening infections in humans, especially in the elderly and in compromised hosts in whom they cause hospital-acquired infections. The present review concentrates on the photoinactivation of Staphylococi, Streptococci, Propionibacterium acnes, Deinococcus radiodurans, aerobic spore-forming Bacilli by various photosensitizers and by various methods described in numerous works and patents. PMID:23550546

Nitzan, Yeshayahu; Nisnevitch, Marina

2013-08-01

180

Airborne bacteria as cloud condensation nuclei  

NASA Astrophysics Data System (ADS)

Bacteria cultivated from aerosol and cloud water samples collected at a remote Austrian mountain site under wintry conditions were tested for their ability to act as cloud condensation nuclei (CCN). The experiment was carried out with a cloud condensation nuclei counter (CCNC) operating on the principle of a static thermal diffusion chamber. Average concentrations of cultivable airborne bacteria amounted to 8 colony forming units (CFU) m-3 in aerosol samples and to 79 CFU mL-1 in cloud water. The set of tested bacteria comprised Gram positive and Gram negative but no known ice nucleating species. At supersaturations between 0.07 and 0.11% all types of bacteria were activated as CCN. As the sizes of the bacteria were smaller than the Kelvin diameters for the respective supersaturations, the physico-chemical properties of their outer cell walls must have enhanced their CCN activity.

Bauer, Heidi; Giebl, Heinrich; Hitzenberger, Regina; Kasper-Giebl, Anne; Reischl, Georg; Zibuschka, Franziska; Puxbaum, Hans

2003-11-01

181

Bacteria produce the volatile hydrocarbon isoprene  

Microsoft Academic Search

Various bacterial species, both Gram-negative and Gram-positive, were found to produce the volatile hydrocarbon isoprene (2-methyl-1,3-butadiene). Out of the tested cultures, Bacillus produced the most isoprene. The production of isoprene from bacteria was confirmed by gas chromatography-mass spectrometry. Media and growth effects on isoprene production were investigated: growth in rich media led to higher levels of isoprene than growth in

Jennifer Kuzma; Michele Nemecek-Marshall; Walter H. Pollock; Ray Fall

1995-01-01

182

Biosynthesis of Auxin by the Gram-Positive Phytopathogen Rhodococcus fascians Is Controlled by Compounds Specific to Infected Plant Tissues  

Microsoft Academic Search

The role and metabolism of indole-3-acetic acid in gram-negative bacteria is well documented, but little is known about indole-3-acetic acid biosynthesis and regulation in gram-positive bacteria. The phytopathogen Rhodococcus fascians, a gram-positive organism, incites diverse developmental alterations, such as leafy galls, on a wide range of plants. Phenotypic analysis of a leafy gall suggests that auxin may play an important

Olivier Vandeputte; Sevgi Oden; Adeline Mol; Danny Vereecke; Koen Goethals; Mondher El Jaziri; Els Prinsen

2005-01-01

183

Protection from Lethal Gram-positive Infection by Macrophage Scavenger Receptor-dependent Phagocytosis  

Microsoft Academic Search

Infections with gram-positive bacteria are a major cause of morbidity and mortality in humans. Opsonin-dependent phagocytosis plays a major role in protection against and recovery from gram-positive infections. Inborn and acquired defects in opsonin generation and\\/or recognition by phagocytes are associated with an increased susceptibility to bacterial infections. In contrast, the physiological significance of opsonin-independent phagocytosis is unknown. Type I

Christian A. Thomas; Yongmei Li; Tatsuhiko Kodama; Hiroshi Suzuki; Samuel C. Silverstein; Joseph El Khoury

184

?Hall chip for sensitive detection of bacteria.  

PubMed

Sensitive, rapid and phenotype-specific enumeration of pathogens is essential for the diagnosis of infectious disease, monitoring of food chains, and for defense against bioterrorism. Microbiological culture and genotyping, techniques that sensitively and selectively detect bacteria in laboratory settings, have limited application in clinical environments due to high cost, slow response times, and the need for specially trained staff and laboratory infrastructure. To address these challenges, we developed a microfluidic chip-based micro-Hall (?Hall) platform capable of measuring single, magnetically tagged bacteria directly in clinical specimens with minimal sample processing. We demonstrated the clinical utility of the ?Hall chip by enumerating Gram-positive bacteria. The overall detection limit of the system was similar to that of culture tests (~10 bacteria), but the assay time was 50-times faster. This low-cost, single-cell analytical technique is especially well-suited to diagnose infectious diseases in resource-limited clinical settings. PMID:23495188

Issadore, David; Chung, Hyun Jung; Chung, Jaehoon; Budin, Ghyslain; Weissleder, Ralph; Lee, Hakho

2013-09-01

185

Search for Cross-Reacting Antigens to Acidogenic Bacteria of the Human Oral Flora.  

National Technical Information Service (NTIS)

Gram positive bacteria were isolated from human saliva, nasal passages, skin and stool specimens and tested by immunofluorescence for antigens shared with Streptococcus sanguis and Streptococcus mutans. Rabbit antisera prepared to Streptococcus mitior and...

M. W. Stinson J. M. Merrick R. J. Nisengard

1982-01-01

186

Staining of Bacteria in Tissue Sections: A Reliable Gram Stain Method.  

National Technical Information Service (NTIS)

A consistently reliable Gram stain procedure which differentially stains both Gram-positive and Gram-negative bacteria in tissue sections is presented. A comparison of this new method with well known Gram stain methods demonstrates its superiority in diff...

H. C. Hopps R. C. Brown

1972-01-01

187

Moderately halophilic gram-positive bacterial diversity in hypersaline environments.  

PubMed

Moderately halophilic bacteria are microorganisms that grow optimally in media containing 3%-15% (w/v) salt. They are represented by a heterogeneous group of microorganisms included in many different genera. Gram-negative moderately halophilic bacteria have been studied in more detail, but studies on gram-positive species are more scarce. Recent studies carried out by our research group on gram-positive moderate halophiles have permitted clarifying their taxonomic and phylogenetic position and describing new species. Thus, we have isolated six strains from ponds of salterns that show phenotypic and genotypic characteristics similar to those of Nesterenkonia halobia (formerly Micrococcus halobius), a moderately halophilic gram-positive coccus that was described on the basis of a single strain. Our data demonstrate quite clearly that they are members of this species and contribute to a better description of these moderately halophilic cocci. Similarly, a study of a large number of gram-positive moderately halophilic rods that were able to produce endospores led us to describe a new species, designated Bacillus salexigens. Further, isolates grouped in other three phenons, obtained by numerical taxonomy analysis and showing phenotypic features quite similar to those of this species, represent different genomovars, with very low DNA-DNA homology. Although they might represent additional new species, it will be necessary to determine new phenotypic features to differentiate them from previously described Bacillus species. We have also studied the viability of some old enrichments provided by B.E. Volcani, which were set up in 1936. We isolated 31 gram-positive motile endospore-forming rods that, according to their phenotypic characteristics, could represent a new species of the genus Bacillus. PMID:9783177

Ventosa, A; Márquez, M C; Garabito, M J; Arahal, D R

1998-08-01

188

Horizontal spread of mer operons among Gram-positive bacteria in natural environments  

Microsoft Academic Search

Horizontal dissemination of the genes responsible for resistance to toxic pollutants may play a key role in the adaptation of bacterial populations to environmental contaminants. However, the frequency and extent of gene dissemination in natural environments is not known. A natural horizontal spread of two distinct mercury resistance (mer) operon variants, which occurred amongst diverse Bacillus and related species over

E. S. Bogdanova; I. A. Bass; L. S. Minakhin; M. A. Petrova; S. Z. Mindlin; A. A. Volodin; E. S. Kalyaeva; J. M. Tiedje; J. L. Hobman; N. L. Brown; V. G. Nikiforov

1998-01-01

189

Functional Analysis of Alkane Hydroxylases from Gram-Negative and Gram-Positive Bacteria  

PubMed Central

We have cloned homologs of the Pseudomonas putida GPo1 alkane hydroxylase from Pseudomonas aeruginosa PAO1, Pseudomonas fluorescens CHA0, Alcanivorax borkumensis AP1, Mycobacterium tuberculosis H37Rv, and Prauserella rugosa NRRL B-2295. Sequence comparisons show that the level of protein sequence identity between the homologs is as low as 35%, and that the Pseudomonas alkane hydroxylases are as distantly related to each other as to the remaining alkane hydroxylases. Based on the observation that rubredoxin, an electron transfer component of the GPo1 alkane hydroxylase system, can be replaced by rubredoxins from other alkane hydroxylase systems, we have developed three recombinant host strains for the functional analysis of the novel alkane hydroxylase genes. Two hosts, Escherichia coli GEc137 and P. putida GPo12, were equipped with pGEc47?B, which encodes all proteins necessary for growth on medium-chain-length alkanes (C6 to C12), except a functional alkane hydroxylase. The third host was an alkB knockout derivative of P. fluorescens CHA0, which is no longer able to grow on C12 to C16 alkanes. All alkane hydroxylase homologs, except the Acinetobacter sp. ADP1 AlkM, allowed at least one of the three hosts to grow on n-alkanes.

Smits, Theo H. M.; Balada, Stefanie B.; Witholt, Bernard; van Beilen, Jan B.

2002-01-01

190

Quinupristin-Dalfopristin Resistance among Gram-Positive Bacteria in Taiwan  

Microsoft Academic Search

susceptible enterococci (85%), vancomycin-resistant Enterococcus faecalis (100%), vancomycin-resistant Entero- coccus faecium (66%), Leuconostoc spp. (100%), Lactobacillus spp. (50%), and Pediococcus spp. (87%). All isolates of MSSA, MRSA, S. pneumoniae, and viridans group streptococci were susceptible to vancomycin and teico- planin. The rates of nonsusceptibility to vancomycin and teicoplanin were 5 and 7%, respectively, for CoNS, ranging from 12 and 18%

KWEN-TAY LUH; PO-REN HSUEH; LEE-JENE TENG; HUI-JU PAN; YU-CHI CHEN; JANG-JIH LU; JIUNN-JONG WU; SHEN-WU HO

2000-01-01

191

Gram-Negative versus Gram-Positive (Actinomycete) Nonobligate Bacterial Predators of Bacteria in Soil.  

National Technical Information Service (NTIS)

The existence of nonobligate bacterial predators in soil has been previously reported. Several additional predators were isolated from soil and tested for predation in situ in soil by use of the indirect bacteriophage analysis technique. The trials were c...

L. R. Zeph L. E. Casida

1986-01-01

192

Bacteria Inactivation During Lithotripsy  

NASA Astrophysics Data System (ADS)

The influence of extracorporeal and intracorporeal lithotripsy on the viability of bacteria contained inside artificial kidney stones was investigated in vitro. Two different bacteria were exposed to the action of one extracorporeal shock wave generator and four intracorporeal lithotripters.

Del Sol Quintero, María; Mora, Ulises; Gutiérrez, Jorge; Mues, Enrique; Castaño, Eduardo; Fernández, Francisco; Loske, Achim M.

2006-09-01

193

Probiotic Bacteria and Methods.  

National Technical Information Service (NTIS)

Provided herein are molecular methods for assessing the state of gastrointestinal microflora of an animal, especially a species of poultry, and methods for identifying probiotic bacteria by comparing certain bacteria present in animals fed a diet not cont...

B. G. Harmon, C. L. Hofacre, M. D. Lee

2005-01-01

194

Cell Size Regulation in Bacteria  

NASA Astrophysics Data System (ADS)

Various bacteria such as the canonical gram negative Escherichia coli or the well-studied gram positive Bacillus subtilis divide symmetrically after they approximately double their volume. Their size at division is not constant, but is typically distributed over a narrow range. Here, we propose an analytically tractable model for cell size control, and calculate the cell size and interdivision time distributions, as well as the correlations between these variables. We suggest ways of extracting the model parameters from experimental data, and show that existing data for E. coli supports partial size control, and a particular explanation: a cell attempts to add a constant volume from the time of initiation of DNA replication to the next initiation event. This hypothesis accounts for the experimentally observed correlations between mother and daughter cells as well as the exponential dependence of size on growth rate.

Amir, Ariel

2014-05-01

195

System for detecting bacteria in blood, blood products, and fluids of tissues  

US Patent & Trademark Office Database

The invention provides methods for screening for the presence of a clinically relevant amount of bacteria in donor blood or a blood product from a donor mammal, particularly blood or a blood product that will be transferred from the donor mammal to a recipient mammal. The method comprises contacting a sample of the donor blood or a blood product with a set of binding agents that comprises binding agents that specifically bind to Gram-negative bacterial antigen and/or binding agents that specifically bind to Gram-positive bacterial antigen, and determining binding of the set of binding agents to the sample, wherein binding indicates the presence of a clinically relevant amount of Gram-positive bacteria and/or Gram-negative bacteria in the donor blood or blood product and no binding indicates the absence of a clinically relevant amount of Gram-positive bacteria and/or Gram-negative bacteria in the donor blood or blood product. The invention further provides methods and kits for screening for the presence of a clinically relevant amount of Gram-positive bacteria, Gram-negative bacteria, or both Gram-positive and Gram-negative bacteria in a donor tissue by screening the fluid in which the donor tissue is stored.

2004-09-14

196

Cell Structure and the Enzymic Lysis of Bacteria  

Microsoft Academic Search

SUMMARY: Untreated cells of three Gram-negative and four Gram-positive bacteria were resistant to lysis by crude and crystallbe trypsin. The resistance of the Gram- negative organisms to lysis by trypsin was abolished by heating suspensions for 5 min. at 100' ; the rates and extent of lysis of the three organisms by crude trypsin were comparable. After maximal lysis of

M. R. J. SALTON

1958-01-01

197

Culturable Airborne Bacteria in Outdoor Poultry-Slaughtering Facility  

PubMed Central

Airborne bacteria are important biological components of the aerosols and have a close relationship with human health as they can have adverse effects through infection and toxicity; higher concentrations can result in various microbial diseases. Moreover, they have a great influence on air quality in Beijing. In this study, a systematic survey on culturable airborne bacteria was carried out for 1 year at a slaughtering plant in Beijing. Bacterial samples were collected with FA-1 sampler for 3 min, three times each day, for three consecutive days of each month from three sampling sites using BIOLOG identification technology. Results showed that Gram-positive bacteria contributed 80%–85% and were much more prevalent than Gram-negative bacteria. Amongst 47 genera of bacteria, including 31 Gram-positive bacteria and 16 Gram-negative bacteria, Micrococcus, Staphylococcus, Bacillus, Corynebacterium, and Pseudomonas were dominant, and Micrococcus, which contributed 20%–30%, was the most dominant genus. The concentration of airborne bacteria was significantly higher in shed used to stay chicken waiting for slaughtering (SSC) and entrances to personnel and transport vehicles with products (EPV) than in green belt (GB). During the year, bacterial concentrations in summer and autumn were much higher than in winter and spring in SSC and EPV, and there were no significant variations in bacterial concentrations in GB. In different periods, a lower concentration of airborne bacteria was found at 13:00.

Liang, Ruiping; Xiao, Peng; She, Ruiping; Han, Shiguo; Chang, Lingling; Zheng, Lingxiao

2013-01-01

198

Species Numbers in Bacteria  

PubMed Central

A modified biological species definition (BSD), i.e., that bacteria exchange genes within a species, but not usually between species, is shown to apply to bacteria. The formal definition of bacterial species, which is more conservative than the modified BSD, is framed in terms of DNA hybridization. From this I estimate there are a million species of bacteria in 30 grams of rich forest topsoil and propose that there will be at least a billion species worldwide.

Dykhuizen, Daniel

2010-01-01

199

Genome size in bacteria  

Microsoft Academic Search

This manuscript examines genome size in bacteria. The opposing capability of bacteria to alter their genome sizes and order\\u000a of genes within limits yet remain somewhat constant provides a mechanism for diversity and evolution in bacterial populations.\\u000a Bacteria may have evolved by increasing their genome size and changing gene orders with the assistance of restriction endonucleases\\u000a cleaving foreign DNA and

J. T. Trevors

1996-01-01

200

Bacteria and lignin degradation  

Microsoft Academic Search

Lignin is both the most abundant aromatic (phenolic) polymer and the second most abundant raw material. It is degraded and\\u000a modified by bacteria in the natural world, and bacteria seem to play a leading role in decomposing lignin in aquatic ecosystems.\\u000a Lignin-degrading bacteria approach the polymer by mechanisms such as tunneling, erosion, and cavitation. With the advantages\\u000a of immense environmental

Jing Li; Hongli Yuan; Jinshui Yang

2009-01-01

201

Metallization of bacteria cells  

Microsoft Academic Search

Bacteria cells with different standard shapes are well suited for use as templates for the fabrication of magnetic and electrically\\u000a conductive microstructures. In this paper, metallization of bacteria cells is demonstrated by an electroless deposition technique\\u000a of nickel-phosphorus initiated by colloid palladium-tin catalyst on the surfaces of Citeromyces matritensis and Bacillus cereus. The activated and metallized bacteria cells have been

Xiangfeng Li; Yaqin Li; Jun Cai; Deyuan Zhang

2003-01-01

202

High efficiency recombineering in lactic acid bacteria  

PubMed Central

The ability to efficiently generate targeted point mutations in the chromosome without the need for antibiotics, or other means of selection, is a powerful strategy for genome engineering. Although oligonucleotide-mediated recombineering (ssDNA recombineering) has been utilized in Escherichia coli for over a decade, the successful adaptation of ssDNA recombineering to Gram-positive bacteria has not been reported. Here we describe the development and application of ssDNA recombineering in lactic acid bacteria. Mutations were incorporated in the chromosome of Lactobacillus reuteri and Lactococcus lactis without selection at frequencies ranging between 0.4% and 19%. Whole genome sequence analysis showed that ssDNA recombineering is specific and not hypermutagenic. To highlight the utility of ssDNA recombineering we reduced the intrinsic vancomymycin resistance of L. reuteri >100-fold. By creating a single amino acid change in the d-Ala-d-Ala ligase enzyme we reduced the minimum inhibitory concentration for vancomycin from >256 to 1.5?µg/ml, well below the clinically relevant minimum inhibitory concentration. Recombineering thus allows high efficiency mutagenesis in lactobacilli and lactococci, and may be used to further enhance beneficial properties and safety of strains used in medicine and industry. We expect that this work will serve as a blueprint for the adaptation of ssDNA recombineering to other Gram-positive bacteria.

van Pijkeren, Jan-Peter; Britton, Robert A.

2012-01-01

203

Regulation of riboflavin biosynthesis and transport genes in bacteria by transcriptional and translational attenuation  

Microsoft Academic Search

The riboflavin biosynthesis in bacteria was analyzed using comparative analysis of genes, operons and regulatory elements. A model for regulation based on formation of alternative RNA structures involving the RFN elements is suggested. In Gram-positive bacteria including actinomycetes, Thermotoga, Thermus and Deinococcus, the riboflavin meta- bolism and transport genes are predicted to be regulated by transcriptional attenuation, whereas in most

Alexey G. Vitreschak; Dmitry A. Rodionov; Andrey A. Mironov; Mikhail S. Gelfand

2002-01-01

204

Application of air ions for bacterial de-colonization in air filters contaminated by aerosolized bacteria  

Microsoft Academic Search

We aerosolized the Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis) bacteria and collected them on membrane filters. Then we generated air ions by applying a high voltage to a carbon fiber tip and applied them to the contaminated filters. The antibacterial efficiency was not significantly affected by the bacteria being Gram-positive or Gram-negative, however, negative ions showed a

Yang Seon Kim; Ki Young Yoon; Jae Hong Park; Jungho Hwang

2011-01-01

205

Studies on the mechanism of bacteria photosensitization by meso-substituted cationic porphyrins  

Microsoft Academic Search

Cationic porphyrins have been shown to photoinduce the direct inactivation of Gram-positive (G+) and Gram-negative (G?) bacteria, thereby differing from anionic or neutral porphyrins which can photosensitize the G? bacteria only after permeabilization of their outer membrane. The present data show that the differences between these positively and negatively charged porphyrins are not related by a difference in the intrinsic

M. Merchat; J. D. Spikes; G. Bertoloni; G. Jori

1996-01-01

206

Strong Synergy between a Eukaryotic Antimicrobial Peptide and Bacteriocins from Lactic Acid Bacteria  

Microsoft Academic Search

The antimicrobial effect obtained upon combining the prokaryotic antimicrobial peptides (AMPs; more commonly referred to as bacteriocins) pediocin PA-1, sakacin P, and curvacin A (all produced by lactic acid bacteria (LAB)) with the eukaryotic AMP pleurocidin (from fish) has been investigated. The three LAB AMPs alone were active against gram-positive Listeria ivanovii bacteria at nanomolar concentrations, whereas they were inactive

Torben Luders; Gunn Alice Birkemo; Gunnar Fimland; Jon Nissen-Meyer; Ingolf F. Nes

2003-01-01

207

Bacteria turn tiny gears  

ScienceCinema

Swarms of bacteria turn two 380-micron long gears, opening the possibility of building hybrid biological machines at the microscopic scale. Read more at Wired: http://www.wired.com/wiredscience/2009/12/bacterial-micro-machine/#more-15684 or Scientific American: http://www.scientificamerican.com/article.cfm?id=brownian-motion-bacteria

208

Chemical communication among bacteria  

PubMed Central

Cell–cell communication in bacteria is accomplished through the exchange of chemical signal molecules called autoinducers. This process, called quorum sensing, allows bacteria to monitor their environment for the presence of other bacteria and to respond to fluctuations in the number and/or species present by altering particular behaviors. Most quorum-sensing systems are species- or group-specific, which presumably prevents confusion in mixed-species environments. However, some quorum-sensing circuits control behaviors that involve interactions among bacterial species. These quorum-sensing circuits can involve both intra- and interspecies communication mechanisms. Finally, anti-quorumsensing strategies are present in both bacteria and eukaryotes, and these are apparently designed to combat bacteria that rely on cell–cell communication for the successful adaptation to particular niches.

Taga, Michiko E.; Bassler, Bonnie L.

2003-01-01

209

2-Arylbenzothiazole, benzoxazole and benzimidazole derivatives as fluorogenic substrates for the detection of nitroreductase and aminopeptidase activity in clinically important bacteria  

Microsoft Academic Search

A series of 2-(2-nitrophenyl)benzothiazole 7, 2-(2-nitrophenyl)benzoxazole 10 and 2-(2-nitrophenyl)benzimidazole 13 derivatives have been synthesised and assessed as indicators of nitroreductase activity across a range of clinically important Gram negative and Gram positive bacteria. The majority of Gram negative bacteria produced strongly fluorescent colonies with substrates 7 and 10 whereas fluorescence production in Gram positive bacteria was less widespread. The l-alanine

Marie Cellier; Olivier J. Fabrega; Elizabeth Fazackerley; Arthur L. James; Sylvain Orenga; John D. Perry; Vindhya L. Salwatura; Stephen P. Stanforth

2011-01-01

210

Pathogenicity of anaerobic gram-positive cocci.  

PubMed Central

The pathogenicity of 20 strains of facultative or anaerobic gram-positive cocci (AGPC) was investigated by injecting them alone or mixed with other flora into mice, utilizing the subcutaneous abscess model. Abscesses induced by a mixture of two organisms were uniformly larger than those induced by single organisms. The relationships among seven AGPC strains, eight aerobes, and two Bacteroides spp. were determined by treating the infected animals with antibiotics and observing the effect of therapy directed against one or both organisms present in the abscess. A total of 70 different combinations were tested. As judged by their responses to antimicrobial therapy, facultative cocci or AGPC were relatively more important than the other species in 6 combinations, equally important in 35 combinations, and less important in 29 combinations. The AGPC most often found to be equal to or more important than the other bacteria were Peptococcus magnus, Streptococcus constellatus, and Peptostreptococcus anaerobius. Proteus mirabilis, Escherichia coli, and Staphylococcus aureus were frequently found to be of more importance than the AGPC.

Brook, I; Walker, R I

1984-01-01

211

Inactivation of biofilm bacteria.  

PubMed Central

The current project was developed to examine inactivation of biofilm bacteria and to characterize the interaction of biocides with pipe surfaces. Unattached bacteria were quite susceptible to the variety of disinfectants tested. Viable bacterial counts were reduced 99% by exposure to 0.08 mg of hypochlorous acid (pH 7.0) per liter (1 to 2 degrees C) for 1 min. For monochloramine, 94 mg/liter was required to kill 99% of the bacteria within 1 min. These results were consistent with those found by other investigators. Biofilm bacteria grown on the surfaces of granular activated carbon particles, metal coupons, or glass microscope slides were 150 to more than 3,000 times more resistant to hypochlorous acid (free chlorine, pH 7.0) than were unattached cells. In contrast, resistance of biofilm bacteria to monochloramine disinfection ranged from 2- to 100-fold more than that of unattached cells. The results suggested that, relative to inactivation of unattached bacteria, monochloramine was better able to penetrate and kill biofilm bacteria than free chlorine. For free chlorine, the data indicated that transport of the disinfectant into the biofilm was a major rate-limiting factor. Because of this phenomenon, increasing the level of free chlorine did not increase disinfection efficiency. Experiments where equal weights of disinfectants were used suggested that the greater penetrating power of monochloramine compensated for its limited disinfection activity. These studies showed that monochloramine was as effective as free chlorine for inactivation of biofilm bacteria. The research provides important insights into strategies for control of biofilm bacteria. Images

LeChevallier, M W; Cawthon, C D; Lee, R G

1988-01-01

212

Clinical update on linezolid in the treatment of Gram-positive bacterial infections  

PubMed Central

Gram-positive pathogens are a significant cause of morbidity and mortality in both community and health care settings. Glycopeptides have traditionally been the antibiotics of choice for multiresistant Gram-positive pathogens but there are problems with their use, including the emergence of glycopeptide-resistant strains, tissue penetration, and achieving and monitoring adequate serum levels. Newer antibiotics such as linezolid, a synthetic oxazolidinone, are available for the treatment of resistant Gram-positive bacteria. Linezolid is active against a wide range of Gram-positive bacteria and has been generally available for the treatment of Gram-positive infections since 2000. There are potential problems with linezolid use, including its bacteriostatic action and the relatively high incidence of reported adverse effects, particularly with long-term use. Long-term use may also be complicated by the development of resistance. However, linezolid has been shown to be clinically useful in the treatment of several serious infections where traditionally bacteriocidal agents have been required and many of its adverse effects are reversible on cessation. It has also been shown to be a cost-effective treatment option in several studies, with its high oral bioavailability allowing an early change from intravenous to oral formulations with consequent earlier patient discharge and lower inpatient costs.

Ager, Sally; Gould, Kate

2012-01-01

213

Interspecies communication in bacteria  

PubMed Central

Until recently, bacteria were considered to live rather asocial, reclusive lives. New research shows that, in fact, bacteria have elaborate chemical signaling systems that enable them to communicate within and between species. One signal, termed AI-2, appears to be universal and facilitates interspecies communication. Many processes, including virulence factor production, biofilm formation, and motility, are controlled by AI-2. Strategies that interfere with communication in bacteria are being explored in the biotechnology industry with the aim of developing novel antimicrobials. AI-2 is a particularly attractive candidate for such studies because of its widespread use in the microbial kingdom.

Federle, Michael J.; Bassler, Bonnie L.

2003-01-01

214

Multidrug Resistance in Bacteria  

PubMed Central

Large amounts of antibiotics used for human therapy, as well as for farm animals and even for fish in aquaculture, resulted in the selection of pathogenic bacteria resistant to multiple drugs. Multidrug resistance in bacteria may be generated by one of two mechanisms. First, these bacteria may accumulate multiple genes, each coding for resistance to a single drug, within a single cell. This accumulation occurs typically on resistance (R) plasmids. Second, multidrug resistance may also occur by the increased expression of genes that code for multidrug efflux pumps, extruding a wide range of drugs. This review discusses our current knowledge on the molecular mechanisms involved in both types of resistance.

Nikaido, Hiroshi

2010-01-01

215

Evaluation of the VITEK 2 gram positive (GP) microbial identification test card: collaborative study.  

PubMed

A collaborative study was conducted to evaluate the performance of the VITEK 2 Gram Positive (GP) identification card for use with the VITEK 2 automated microbial identification system. The GP test card is used in the identification of selected Gram positive organisms, including Listeria and Staphylococcus species. The VITEK 2 GP card is based on 43 biochemical tests measuring carbon source utilization, inhibition and resistance, and enzymatic activities. A total of 20 laboratories representing government, industry, and private testing laboratories throughout the United States participated. In this study, 720 Gram-positive inclusivity isolates were analyzed by the GP Identification method. Of the 720 well-characterized isolates, 714 were identified correctly, zero were misidentified, zero were unidentified, and six were not characterized as a Gram-positive organism by the VITEK 2 GP method. Additionally, 120 strains exclusive of Gram-positive organisms were screened by Gram stain. A total of 106 isolates were correctly excluded. Fourteen organisms were incorrectly characterized by Gram stain procedures, thus resulting in improper analysis and misidentification by VITEK GP. The VITEK 2 GP identification method is an acceptable automated method for the rapid identification of selected Gram-positive bacteria. PMID:23175976

Crowley, Erin; Bird, Patrick; Fisher, Kiel; Goetz, Katherine; Boyle, Megan; Benzinger, M Joseph; Juenger, Marc; Agin, James; Goins, David; Johnson, Ronald L

2012-01-01

216

Vancomycin-Resistant Gram-Positive Cocci Isolated from the Saliva of Wild Songbirds  

PubMed Central

We analyzed highly vancomycin-resistant Gram-positive bacteria isolated from the saliva of migratory songbirds captured, sampled, and released from a birdbanding station in western Kansas. Individual bacterial isolates were identified by partial 16S rRNA sequencing. Most of the bacteria in this study were shown to be Staphylococcus succinus with the majority being isolated from the American Robin. Some of these bacteria were shown to carry vanA, vanB, and vanC vancomycin-resistance genes and have the ability to form biofilms. One of the van gene-carrying isolates is also coagulase positive, which is normally considered a virulence factor. Other organisms isolated included Staphylococcus saprophyticus as well as Enterococcus gallinarum. Given the wide range of the American Robin and ease of horizontal gene transfer between Gram-positive cocci, we postulate that these organisms could serve as a reservoir of vancomycin-resistance genes capable of transferring to human pathogens.

Ishihara, Shingo; Bitner, Jessica J.; Farley, Greg H.

2014-01-01

217

Semiquantitation of bacteria in sputum gram stains.  

PubMed Central

In many clinical laboratories, bacteria seen in Gram-stained sputum smears are reported semiquantitatively, using a three- or four-category scale consisting of ratings such as numerous, moderate, rare, and none seen. The consistency with which these categories are assigned was evaluated by repeatedly presenting coded smears to seven experienced microbiology technologists. Technologists rated the same smear twice, pairs of smears prepared from the same specimen, and smears prepared after specimen refrigeration. Agreement was assessed with the weighted kappa test. Semiquantitation of gram-negative rods, gram-positive diplococci, and gram-positive cocci in clusters all showed poor reproducibility (kappa = 0.32, 0.34, and 0.17, respectively). Twenty-four percent of paired ratings differed by two or more categories. Lack of reproducibility was due mainly to the inability of the technologists to render a consistent rating when viewing the same slide on separate occasions (P less than 0.001). Variation in the rating styles of different technologists, differences between smears prepared from the same specimen, and specimen refrigeration tended to further decrease the consistency of ratings, but the reductions were not statistically significant. The quantity of potentially pathogenic bacteria in sputum smears is not estimated consistently with standard microscopy procedures and should not be reported.

Valenstein, P N

1988-01-01

218

Bacteria and Foodborne Illness  

MedlinePLUS

... types of bacteria cause foodborne illnesses. Examples include Salmonella , a bacterium found in many foods, including raw and undercooked meat, poultry, dairy products, and seafood. Salmonella may also be present on egg shells and ...

219

Cultivation Media for Bacteria  

NSDL National Science Digital Library

Common bacteriological culture media (tryptic soy agar, chocolate agar, Thayer-Martin agar, MacConkey agar, eosin-methylene blue agar, hektoen agar, mannitol salt agar, and sheep blood agar) are shown uninoculated and inoculated with bacteria.

American Society For Microbiology;

2009-12-08

220

Phosphatidic Acid Synthesis in Bacteria  

PubMed Central

Membrane phospholipid synthesis is a vital facet of bacterial physiology. Although the spectrum of phospholipid headgroup structures produced by bacteria is large, the key precursor to all of these molecules is phosphatidic acid (PtdOH). Glycerol-3-phosphate derived from the glycolysis via glycerol-phosphate synthase is the universal source for the glycerol backbone of PtdOH. There are two distinct families of enzymes responsible for the acylation of the 1-position of glycerol-3-phosphate. The PlsB acyltransferase was discovered in Escherichia coli, and homologs are present in many eukaryotes. This protein family primarily uses acyl-acyl carrier protein (ACP) endproducts of fatty acid synthesis as acyl donors, but may also use acyl-CoA derived from exogenous fatty acids. The second protein family, PlsY, is more widely distributed in bacteria and utilizes the unique acyl donor, acyl-phosphate, which is produced from acyl-ACP by the enzyme PlsX. The acylation of the 2-position is carried out by members of the PlsC protein family. All PlsCs use acyl-ACP as the acyl donor, although the PlsCs of the ?-proteobacteria also may use acyl-CoA. Phospholipid headgroups are precursors in the biosynthesis of other membrane-associated molecules and the diacylglycerol product of these reactions is converted to PtdOH by one of two distinct families of lipid kinases. The central importance of the de novo and recycling pathways to PtdOH in cell physiology suggest these enzymes are suitable targets for the development of antibacterial therapeutics in Gram-positive pathogens. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.

Yao, Jiangwei; Rock, Charles O.

2012-01-01

221

Ecophysiology of Magnetotactic Bacteria  

Microsoft Academic Search

Magnetotactic bacteria are a physiologically diverse group of prokaryotes whose main common features\\u000a are the biomineralization of magnetosomes and magnetotaxis, the passive alignment and active motility along\\u000a geomagnetic field lines. Magnetotactic bacteria exist in their highest numbers at or near the oxic–anoxic\\u000a interfaces (OAI) of chemically stratified aquatic habitats that contain inverse concentration gradients\\u000a of oxidants and reductants. Few species are

Dennis A. Bazylinski; Timothy Williams

222

Iron Storage in Bacteria  

Microsoft Academic Search

Iron is an essential nutrient for nearly all organisms but presents problems of toxicity, poor solubility and low availability. These problems are alleviated through the use of iron-storage proteins. Bacteria possess two types of iron-storage protein, the haemcontaining bacterioferritins and the haem-free ferritins. These proteins are widespread in bacteria, with at least 39 examples known so far in eubacteria and

Simon C. Andrews

1998-01-01

223

Aerobic Anoxygenic Phototrophic Bacteria  

PubMed Central

The aerobic anoxygenic phototrophic bacteria are a relatively recently discovered bacterial group. Although taxonomically and phylogenetically heterogeneous, these bacteria share the following distinguishing features: the presence of bacteriochlorophyll a incorporated into reaction center and light-harvesting complexes, low levels of the photosynthetic unit in cells, an abundance of carotenoids, a strong inhibition by light of bacteriochlorophyll synthesis, and the inability to grow photosynthetically under anaerobic conditions. Aerobic anoxygenic phototrophic bacteria are classified in two marine (Erythrobacter and Roseobacter) and six freshwater (Acidiphilium, Erythromicrobium, Erythromonas, Porphyrobacter, Roseococcus, and Sandaracinobacter) genera, which phylogenetically belong to the ?-1, ?-3, and ?-4 subclasses of the class Proteobacteria. Despite this phylogenetic information, the evolution and ancestry of their photosynthetic properties are unclear. We discuss several current proposals for the evolutionary origin of aerobic phototrophic bacteria. The closest phylogenetic relatives of aerobic phototrophic bacteria include facultatively anaerobic purple nonsulfur phototrophic bacteria. Since these two bacterial groups share many properties, yet have significant differences, we compare and contrast their physiology, with an emphasis on morphology and photosynthetic and other metabolic processes.

Yurkov, Vladimir V.; Beatty, J. Thomas

1998-01-01

224

Evaluation of the antibacterial potential of Petroselinum crispum and Rosmarinus officinalis against bacteria that cause urinary tract infections  

PubMed Central

In this study we evaluated the antibacterial activity of the crude hydroalcoholic extracts, fractions, and compounds of two plant species, namely Rosmarinus officinalis and Petroselinum crispum, against the bacteria that cause urinary tract infection. The microdilution method was used for determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The crude hydroalcoholic extract of R. officinalis displayed in vitro activity against Gram-positive bacteria, with satisfactory MBC for the clinical isolate S. saprophyticus. The fractions and the pure compound rosmarinic acid did not furnish promising results for Gram-negative bacteria, whereas fractions 2, 3, and 4 gave encouraging results for Gram-positive bacteria and acted as bactericide against S. epidermidis as well as E. faecalis (ATCC 29212) and its clinical isolate. R. officinalis led to promising results in the case of Gram-positive bacteria, resulting in a considerable interest in the development of reliable alternatives for the treatment of urinary infections.

Petrolini, Fernanda Villas Boas; Lucarini, Rodrigo; de Souza, Maria Gorete Mendes; Pires, Regina Helena; Cunha, Wilson Roberto; Martins, Carlos Henrique Gomes

2013-01-01

225

PVC biodeterioration and DEHP leaching by DEHP-degrading bacteria.  

PubMed

Newly isolated, not previously reported, di-(2-ethylhexyl) phthalate (DEHP)-degraders were augmented to assess their role in polyvinyl chloride (PVC) shower curtain deterioration and DEHP leaching. The biofilms that developed on the surfaces of the bioaugmented shower curtains with Gram-positive strains LHM1 and LHM2 were thicker than those of the biostimulated and Gram-negative strain LHM3-augmented shower curtains. The first derivative thermogravimetric (DTG) peaks of the bioaugmented shower curtains with the Gram-positive bacteria were observed at ~287°C, whereas the control and Gram-negative strain LHM3-augmented shower curtains were detected at ~283°C. This slight delay in the first DTG peak temperature is indicative of lower plasticizer concentrations in the shower curtains that were bioaugmented with Gram positive bacteria. Despite bioaugmentation with DEHP-degraders, aqueous solutions of the bioaugmentation reactors were not DEHP-free due probably to the presence of co-solutes that must have supported microbial growth. Generally, the bioaugmented reactors with the Gram-positive strains LHM1 and LHM2 had greater aqueous DEHP concentrations in the first-half (<3 wk) of the biodeterioration experiment than the biostimulated and strain LHM3-augmented reactors. Therefore, strains LHM1 and LHM2 may play an important role in DEHP leaching to the environment and PVC biodeterioration. PMID:22736894

Latorre, Isomar; Hwang, Sangchul; Sevillano, Maria; Montalvo-Rodriguez, Rafael

2012-04-01

226

PVC biodeterioration and DEHP leaching by DEHP-degrading bacteria  

PubMed Central

Newly isolated, not previously reported, di-(2-ethylhexyl) phthalate (DEHP)-degraders were augmented to assess their role in polyvinyl chloride (PVC) shower curtain deterioration and DEHP leaching. The biofilms that developed on the surfaces of the bioaugmented shower curtains with Gram-positive strains LHM1 and LHM2 were thicker than those of the biostimulated and Gram-negative strain LHM3-augmented shower curtains. The first derivative thermogravimetric (DTG) peaks of the bioaugmented shower curtains with the Gram-positive bacteria were observed at ~287°C, whereas the control and Gram-negative strain LHM3-augmented shower curtains were detected at ~283°C. This slight delay in the first DTG peak temperature is indicative of lower plasticizer concentrations in the shower curtains that were bioaugmented with Gram positive bacteria. Despite bioaugmentation with DEHP-degraders, aqueous solutions of the bioaugmentation reactors were not DEHP-free due probably to the presence of co-solutes that must have supported microbial growth. Generally, the bioaugmented reactors with the Gram-positive strains LHM1 and LHM2 had greater aqueous DEHP concentrations in the first-half (<3 wk) of the biodeterioration experiment than the biostimulated and strain LHM3-augmented reactors. Therefore, strains LHM1 and LHM2 may play an important role in DEHP leaching to the environment and PVC biodeterioration.

Latorre, Isomar; Hwang, Sangchul; Sevillano, Maria; Montalvo-Rodriguez, Rafael

2012-01-01

227

Metabolic engineering of bacteria for ethanol production  

SciTech Connect

Technologies are available which will allow the conversion of lignocellulose into fuel ethanol using genetically engineered bacteria. Assembling these into a cost-effective process remains a challenge. The authors` work has focused primarily on the genetic engineering of enteric bacteria using a portable ethanol production pathway. Genes encoding Zymomonas mobilis pyruvate decarboxylase and alcohol dehydrogenase have been integrated into the chromosome of Escherichia coli B to produce strain KO11 for the fermentation of hemicellulose-derived syrups. This organism can efficiently ferment all hexose and pentose sugars present in the polymers of hemicellulose. Klebsiella oxytoca M5A1 has been genetically engineered in a similar manner to produce strain P2 for ethanol production from cellulose. This organism has the native ability to ferment cellobiose and cellotriose, eliminating the need for one class of cellulase enzymes. The optimal pH for cellulose fermentation with this organism is near that of fungal cellulases. The general approach for the genetic engineering of new biocatalysts has been most successful with enteric bacteria thus far. However, this approach may also prove useful with gram-positive bacteria which have other important traits for lignocellulose conversion. Many opportunities remain for further improvements in the biomass to ethanol processes.

Ingram, L.O.; Gomez, P.F.; Lai, X.; Moniruzzaman, M.; Wood, B.E.; Yomano, L.P.; York, S.W. [Univ. of Florida, Gainesville, FL (United States). Dept. of Microbiology and Cell Science] [Univ. of Florida, Gainesville, FL (United States). Dept. of Microbiology and Cell Science

1998-04-20

228

Endocarditis Due to Rare and Fastidious Bacteria  

PubMed Central

The etiologic diagnosis of infective endocarditis is easily made in the presence of continuous bacteremia with gram-positive cocci. However, the blood culture may contain a bacterium rarely associated with endocarditis, such as Lactobacillus spp., Klebsiella spp., or nontoxigenic Corynebacterium, Salmonella, Gemella, Campylobacter, Aeromonas, Yersinia, Nocardia, Pasteurella, Listeria, or Erysipelothrix spp., that requires further investigation to establish the relationship with endocarditis, or the blood culture may be uninformative despite a supportive clinical evaluation. In the latter case, the etiologic agents are either fastidious extracellular or intracellular bacteria. Fastidious extracellular bacteria such as Abiotrophia, HACEK group bacteria, Clostridium, Brucella, Legionella, Mycobacterium, and Bartonella spp. need supplemented media, prolonged incubation time, and special culture conditions. Intracellular bacteria such as Coxiella burnetii cannot be isolated routinely. The two most prevalent etiologic agents of culture-negative endocarditis are C. burnetti and Bartonella spp. Their diagnosis is usually carried out serologically. A systemic pathologic examination of excised heart valves including periodic acid-Schiff (PAS) staining and molecular methods has allowed the identification of Whipple's bacillus endocarditis. Pathologic examination of the valve using special staining, such as Warthin-Starry, Gimenez, and PAS, and broad-spectrum PCR should be performed systematically when no etiologic diagnosis is evident through routine laboratory evaluation.

Brouqui, P.; Raoult, D.

2001-01-01

229

[Bacteria isolated from surgical infections and its susceptibilities to antimicrobial agents--special references to bacteria isolated between April 2009 and March 2010].  

PubMed

Bacteria isolated from surgical infections during the period from April 2009 to March 2010 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, 671 strains including 16 strains of Candida spp. were isolated from 174 (79.1%) of 220 patients with surgical infections. Four hundred and eleven strains were isolated from primary infections, and 244 strains were isolated from surgical site infection. From primary infections, anaerobic Gram-negative bacteria were predominant, followed by aerobic Gram-negative bacteria, while from surgical site infection aerobic Gram-positive bacteria were predominant, followed by anaerobic Gram-negative bacteria. Among aerobic Gram-positive bacteria, the isolation rate of Enterococcus spp. was highest, followed by Streptococcus spp., and Staphylococcus spp. in this order, from primary infections, while Enterococcus spp. was highest, followed by Staphylococcus spp. from surgical site infection. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Klebsiella pneumoniae, Enterobacter cloacae and Pseudomonas aeruginosa, in this order, and from surgical site infection, E. coli was most predominantly isolated, followed by P. aeruginosa and E. cloacae. Among anaerobic Gram-positive bacteria, the isolation rate of Eggerthella lenta was the highest from primary infections, followed by Parvimonas micra, Streptococcus constellatus and Finegoldia magna, and from surgical site infection, E. lenta was most predominantly isolated. Among anaerobic Gram-negative bacteria, the isolation rate of Bilophila wadsworthia was the highest from primary infections, followed by Bacteroides fragilis, Bacteroides ovatus and Bacteroides thetaiotaomicron, and from surgical site infection, B. fragilis was most predominantly isolated, followed by B. ovatus, B. wadsworthia and B. thetaiotaomicron, in this order. In this series, we noticed no vancomycin-resistant Gram-positive cocci, nor multidrug-resistant P. aeruginosa. We should carefully follow up B. wadsworthia which was resistant to various antibiotics, and also Bacteroides spp. which was resistant to many beta-lactam antibiotics. PMID:21861307

Shinagawa, Nagao; Osanai, Hiroyuki; Hirata, Koichi; Furuhata, Tomohisa; Mizukuchi, Tohru; Yanai, Yoshiyuki; Hata, Fumitake; Taniguchi, Masaaki; Sasaki, Kazuaki; Someya, Tetsufumi; Sasaki, Kazunori; Oono, Keisuke; Mizuno, Isamu; Shamoto, Tomoya; Fukui, Takuji; Tokita, Shoji; Nakamura, Masashi; Mashita, Keiji; Shibuya, Hitoshi; Tanaka, Moritsugu; Hasegawa, Itaru; Kimura, Masami; Oshima, Hideki; Maeda, Hideki; Ishikawa, Syu; Mukaiya, Mitsuhiro; Kihara, Chikasi; Mizuno, Akira; Watabe, Kosho; Iwai, Akihiko; Saito, Takaaki; Hoshikawa, Tsuyoshi; Kimura, Hitoshi; Moori, Noriaki; Sumita, Naoki; Jae-Hoon, Yoo; Kubo, Shoji; Lee, Shigeru; Aikawa, Naoki; Sekine, Kazuhiko; Abe, Shinya; Oomura, Toru; Takeyama, Hiromitsu; Wakasugi, Takehiro; Kobayashi, Yasuhito; Tsuji, Takeshi; Yamaue, Hiroki; Ozawa, Satoru; Takesue, Yoshio; Fujiwara, Toshiyoshi; Tsumura, Hiroaki; Kimura, Hideyuki; Yokoyama, Takashi; Iwagaki, Hiromi; Takeuchi, Hitoshi; Tanakaya, Kouji; Sueda, Taijiro; Hiyama, Eiso; Murakami, Yoshiaki; Ohge, Hiroki; Uemura, Kenichiro; Yasunami, Yoichi; Sasaki, Takamitsu

2011-06-01

230

A Flow-Cytometric Gram-Staining Technique for Milk-Associated Bacteria  

PubMed Central

A Gram-staining technique combining staining with two fluorescent stains, Oregon Green-conjugated wheat germ agglutinin (WGA) and hexidium iodide (HI) followed by flow-cytometric detection is described. WGA stains gram-positive bacteria while HI binds to the DNA of all bacteria after permeabilization by EDTA and incubation at 50°C for 15 min. For WGA to bind to gram-positive bacteria, a 3 M potassium chloride solution was found to give the highest fluorescence intensity. A total of 12 strains representing some of the predominant bacterial species in bulk tank milk and mixtures of these were stained and analyzed by flow cytometry. Overall, the staining method showed a clear differentiation between gram-positive and gram-negative bacterial populations. For stationary-stage cultures of seven gram-positive bacteria and five gram-negative bacteria, an average of 99% of the cells were correctly interpreted. The method was only slightly influenced by the growth phase of the bacteria or conditions such as freezing at ?18°C for 24 h. For any of these conditions, an average of at least 95% of the cells were correctly interpreted. When stationary-stage cultures were stored at 5°C for 14 days, an average of 86% of the cells were correctly interpreted. The Gram-staining technique was applied to the flow cytometry analysis of bulk tank milk inoculated with Staphylococcus aureus and Escherichia coli. These results demonstrate that the technique is suitable for analyzing milk samples without precultivation.

Holm, Claus; Jespersen, Lene

2003-01-01

231

Photothermolysis of immobilized bacteria on gold nanograil arrays  

NASA Astrophysics Data System (ADS)

Photothermolysis technique via array of gold nanograils had been developed by illuminating near infrared laser light onto captured bacteria in metal nanostructure. The strong electromagnetic field enhancement at the sharp edges of the gold nanograils produced local heating that was sufficient to break the thick cell walls of the gram-positive Staphylococcus aureus cells within a short time. Individual cells in the nanograil array can be selectively lysed by adjusting the laser scanning area to the micrometer scale.

Kim, Soo Kyung; Heo, Chul-Joon; Choi, Jong Young; Lee, Su Yeon; Jang, Se Gyu; Won Shim, Jae; Seo, Tae Seok; Yang, Seung-Man

2011-06-01

232

Two-peptide bacteriocins produced by lactic acid bacteria  

Microsoft Academic Search

Bacteriocins from lactic acid bacteria are ribosomally produced peptides (usually 30–60 amino acids) that display potent antimicrobial activity against certain other Gram-positive organisms. They function by disruption of the membrane of their targets, mediated in at least some cases by interaction of the peptide with a chiral receptor molecule (e.g., lipid II or sugar PTS proteins). Some bacteriocins are unmodified

Sylvie Garneau; Nathaniel I Martin; John C Vederas

2002-01-01

233

Characterization of bacteria from a swine manure digester  

SciTech Connect

One-hundred thirty bacteria isolated from a swine manure digester were predominately gram-positive anaerobes which were tentatively classified into the following genera: Peptostreptococcus, Eubacterium, Bacteroides, Lactobacillus, Peptococcus, Clostridiu, and Streptococcus plus two unidentified groups. The major fermentation products formed by these organisms included acetate, propionate, succinate, lactate, and ethanol, singly or in various combinations. Acetate was the sole end product of several groups. Few of the isolates (14%) reduced the pH below 6.0. The predominate bacteria appear to differ from the predominate organisms isolated from other anaerobic ecosystems.

Iannotti, E.L. (Univ. of Missouri, Columbia); Fischer, J.R.; Sievers, D.M.

1982-01-01

234

Biofilm bacteria: formation and comparative susceptibility to antibiotics  

PubMed Central

The Calgary Biofilm Device (CBD) was used to form bacterial biofilms of selected veterinary gram-negative and gram-positive pathogenic bacteria from cattle, sheep, pigs, chicken, and turkeys. The minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) of ampicillin, ceftiofur, cloxacillin, oxytetracycline, penicillin G, streptomycin, tetracycline, enrofloxacin, erythromycin, gentamicin, tilmicosin, and trimethoprim-sulfadoxine for gram-positive and -negative bacteria were determined. Bacterial biofilms were readily formed on the CBD under selected conditions. The biofilms consisted of microcolonies encased in extracellular polysaccharide material. Biofilms composed of Arcanobacterium (Actinomyces) pyogenes, Staphylococcus aureus, Staphylococcus hyicus, Streptococcus agalactiae, Corynebacterium renale, or Corynebacterium pseudotuberculosis were not killed by the antibiotics tested but as planktonic bacteria they were sensitive at low concentrations. Biofilm and planktonic Streptococcus dysgalactiae and Streptococcus suis were sensitive to penicillin, ceftiofur, cloxacillin, ampicillin, and oxytetracycline. Planktonic Escherichia coli were sensitive to enrofloxacin, gentamicin, oxytetracycline and trimethoprim/ sulfadoxine. Enrofloxacin and gentamicin were the most effective antibiotics against E. coli growing as a biofilm. Salmonella spp. and Pseudomonas aeruginosa isolates growing as planktonic populations were sensitive to enrofloxacin, gentamicin, ampicillin, oxytetracycline, and trimethoprim/sulfadoxine, but as a biofilm, these bacteria were only sensitive to enrofloxacin. Planktonic and biofilm Pasteurella multocida and Mannheimia haemolytica had similar antibiotic sensitivity profiles and were sensitive to most of the antibiotics tested. The CBD provides a valuable new technology that can be used to select antibiotics that are able to kill bacteria growing as biofilms.

Olson, Merle E.; Ceri, Howard; Morck, Douglas W.; Buret, Andre G.; Read, Ronald R.

2002-01-01

235

Functional properties of novel protective lactic acid bacteria and application in raw chicken meat against Listeria monocytogenes and Salmonella enteritidis  

Microsoft Academic Search

In this study 635 lactic acid bacteria of food origin were evaluated for their potential application as protective cultures in foods. A stepwise selection method was used to obtain the most appropriate strains for application as protective cultures in chicken meat. Specifically, all strains were examined for antimicrobial activity against various Gram positive and Gram negative pathogenic and spoilage bacteria.

Petros A. Maragkoudakis; Konstantinos C. Mountzouris; Dimitris Psyrras; Silvia Cremonese; Jana Fischer; Mette D. Cantor; Effie Tsakalidou

2009-01-01

236

Biofilm Formation by Gram-Negative Bacteria on Central Venous Catheter Connectors: Effect of Conditioning Films in a Laboratory Model  

Microsoft Academic Search

Human blood components have been shown to enhance biofilm formation by gram-positive bacteria. We investigated the effect of human blood on biofilm formation on the inner lumen of needleless central venous catheter connectors by several gram-negative bacteria, specifically Enterobacter cloacae, Pseudomonas aerugi- nosa, and Pantoea agglomerans. Results suggest that a conditioning film of blood components promotes biofilm formation by these

R. Murga; J. M. Miller; R. M. Donlan

2001-01-01

237

Characterizing the Catalytic Potential of Deinococcus, Arthrobacter and other Robust Bacteria in Contaminated Subsurface Environments of the Hanford Site, Annual Report 2006.  

National Technical Information Service (NTIS)

Until recently, there have been no clear physiologic predictors of a cell's ability to recover from ionizing radiation (IR), desiccation, and other DOE-relevant oxidative stress conditions. In general, the most resistant bacteria have been Gram-positive (...

J. K. Fredrickson M. J. Daly

2006-01-01

238

Bacteria-surface interactions  

PubMed Central

The interaction of bacteria with surfaces has important implications in a range of areas, including bioenergy, biofouling, biofilm formation, and the infection of plants and animals. Many of the interactions of bacteria with surfaces produce changes in the expression of genes that influence cell morphology and behavior, including genes essential for motility and surface attachment. Despite the attention that these phenotypes have garnered, the bacterial systems used for sensing and responding to surfaces are still not well understood. An understanding of these mechanisms will guide the development of new classes of materials that inhibit and promote cell growth, and complement studies of the physiology of bacteria in contact with surfaces. Recent studies from a range of fields in science and engineering are poised to guide future investigations in this area. This review summarizes recent studies on bacteria-surface interactions, discusses mechanisms of surface sensing and consequences of cell attachment, provides an overview of surfaces that have been used in bacterial studies, and highlights unanswered questions in this field.

Tuson, Hannah H.; Weibel, Douglas B.

2013-01-01

239

Communication among Oral Bacteria  

PubMed Central

Human oral bacteria interact with their environment by attaching to surfaces and establishing mixed-species communities. As each bacterial cell attaches, it forms a new surface to which other cells can adhere. Adherence and community development are spatiotemporal; such order requires communication. The discovery of soluble signals, such as autoinducer-2, that may be exchanged within multispecies communities to convey information between organisms has emerged as a new research direction. Direct-contact signals, such as adhesins and receptors, that elicit changes in gene expression after cell-cell contact and biofilm growth are also an active research area. Considering that the majority of oral bacteria are organized in dense three-dimensional biofilms on teeth, confocal microscopy and fluorescently labeled probes provide valuable approaches for investigating the architecture of these organized communities in situ. Oral biofilms are readily accessible to microbiologists and are excellent model systems for studies of microbial communication. One attractive model system is a saliva-coated flowcell with oral bacterial biofilms growing on saliva as the sole nutrient source; an intergeneric mutualism is discussed. Several oral bacterial species are amenable to genetic manipulation for molecular characterization of communication both among bacteria and between bacteria and the host. A successful search for genes critical for mixed-species community organization will be accomplished only when it is conducted with mixed-species communities.

Kolenbrander, Paul E.; Andersen, Roxanna N.; Blehert, David S.; Egland, Paul G.; Foster, Jamie S.; Palmer, Robert J.

2002-01-01

240

PATHOGENICITY OF BIOFILM BACTERIA  

EPA Science Inventory

There is a paucity of information concerning any link between the microorganisms commonly found in biofilms of drinking water systems and their impacts on human health. For bacteria, culture-based techniques detect only a limited number of the total microorganisms associated wit...

241

Antibiotic-Resistant Bacteria.  

ERIC Educational Resources Information Center

A study conducted by high school advanced bacteriology students appears to confirm the hypothesis that the incremental administration of antibiotics on several species of bacteria (Escherichia coli, Staphylococcus epidermis, Bacillus sublitus, Bacillus megaterium) will allow for the development of antibiotic-resistant strains. (PEB)

Longenecker, Nevin E.; Oppenheimer, Dan

1982-01-01

242

Vancomycin-resistant Gram-positive bacterial endophthalmitis: epidemiology, treatment options, and outcomes  

PubMed Central

Background The purpose of this study is to evaluate the microbiological profile and treatment outcomes of vancomycin-resistant Gram-positive bacterial endophthalmitis. Medical records of all patients with Gram-positive bacterial endophthalmitis resistant to vancomycin presenting between 1 January 2005 and 31 December 2010 were reviewed in this noncomparative, consecutive, retrospective case series. Favorable outcome was defined as a best-corrected visual acuity of ?20/200. Results Out of 682 culture-positive endophthalmitis isolates, 448/682 (65.6%) were associated with Gram-positive bacteria. In vitro resistance to vancomycin was noted in 7/448 (1.56%). Three cases were posttraumatic, three were postoperative, and one was endogenous in origin. Four Bacillus isolates, two Staphylococcus isolates, and an Enterococcus isolate were resistant. Isolates resistant to vancomycin were sensitive in vitro to ciprofloxacin in 6/7 (86%) patients. Presenting visual acuity was light perception in all seven cases. Favorable outcome was achieved in only 1/7 (14.3%) cases. Conclusions Vancomycin-resistant endophthalmitis is uncommon and usually associated with poor visual outcome. Bacillus sp. is the most frequent Gram-positive bacteria resistant to vancomycin. Fluoroquinolones like ciprofloxacin may be considered as a useful alternative in vancomycin-resistant endophthalmitis.

2013-01-01

243

Susceptibility and resistance of ruminal bacteria to antimicrobial feed additives.  

PubMed Central

Susceptibility and resistance of ruminal bacterial species to avoparcin, narasin, salinomycin, thiopeptin, tylosin, virginiamycin, and two new ionophore antibiotics, RO22-6924/004 and RO21-6447/009, were determined. Generally, antimicrobial compounds were inhibitory to gram-positive bacteria and those bacteria that have gram-positive-like cell wall structure. MICs ranged from 0.09 to 24.0 micrograms/ml. Gram-negative bacteria were resistant at the highest concentration tested (48.0 micrograms/ml). On the basis of their fermentation products, ruminal bacteria that produce lactic acid, butyric acid, formic acid, or hydrogen were susceptible and bacteria that produce succinic acid or ferment lactic acid were resistant to the antimicrobial compounds. Selenomonas ruminantium was the only major lactic acid-producing bacteria resistant to all the antimicrobial compounds tested. Avoparcin and tylosin appeared to be less inhibitory (MIC greater than 6.0 micrograms/ml) than the other compounds to the two major lactic acid-producing bacteria, Streptococcus bovis and Lactobacillus sp. Ionophore compounds seemed to be more inhibitory (MIC, 0.09 to 1.50 micrograms/ml) than nonionophore compounds (MIC, 0.75 to 12.0 micrograms/ml) to the major butyric acid-producing bacteria. Treponema bryantii, an anaerobic rumen spirochete, was less sensitive to virginiamycin than to the other antimicrobial compounds. Ionophore compounds were generally bacteriostatic, and nonionophore compounds were bactericidal. The specific growth rate of Bacteroides ruminicola was reduced by all the antimicrobial compounds except avoparcin. The antibacterial spectra of the feed additives were remarkably similar, and it appears that MICs may not be good indicators of the potency of the compounds in altering ruminal fermentation characteristics.

Nagaraja, T G; Taylor, M B

1987-01-01

244

CcpA-Dependent Carbon Catabolite Repression in Bacteria  

PubMed Central

Carbon catabolite repression (CCR) by transcriptional regulators follows different mechanisms in gram-positive and gram-negative bacteria. In gram-positive bacteria, CcpA-dependent CCR is mediated by phosphorylation of the phosphoenolpyruvate:sugar phosphotransferase system intermediate HPr at a serine residue at the expense of ATP. The reaction is catalyzed by HPr kinase, which is activated by glycolytic intermediates. In this review, the distribution of CcpA-dependent CCR among bacteria is investigated by searching the public databases for homologues of HPr kinase and HPr-like proteins throughout the bacterial kingdom and by analyzing their properties. Homologues of HPr kinase are commonly observed in the phylum Firmicutes but are also found in the phyla Proteobacteria, Fusobacteria, Spirochaetes, and Chlorobi, suggesting that CcpA-dependent CCR is not restricted to gram-positive bacteria. In the ? and ? subdivisions of the Proteobacteria, the presence of HPr kinase appears to be common, while in the ? subdivision it is more of an exception. The genes coding for the HPr kinase homologues of the Proteobacteria are in a gene cluster together with an HPr-like protein, termed XPr, suggesting a functional relationship. Moreover, the XPr proteins contain the serine phosphorylation sequence motif. Remarkably, the analysis suggests a possible relation between CcpA-dependent gene regulation and the nitrogen regulation system (Ntr) found in the ? subdivision of the Proteobacteria. The relation is suggested by the clustering of CCR and Ntr components on the genome of members of the Proteobacteria and by the close phylogenetic relationship between XPr and NPr, the HPr-like protein in the Ntr system. In bacteria in the phylum Proteobacteria that contain HPr kinase and XPr, the latter may be at the center of a complex regulatory network involving both CCR and the Ntr system.

Warner, Jessica B.; Lolkema, Juke S.

2003-01-01

245

Plasmid mediated antibiotic resistance in marine bacteria.  

PubMed

This research work was conducted in Uppanar estuary to ascertain the role of plasmids in the antibiotic resistance of bacteria. Water and sediment samples were collected for a period of three months. When tested against 20 antibiotics 22 MAR strains were isolated from the samples, which were found resistant to 5-13 antibiotics. They belong to 7 genera and 10 species. Gram-negative bacteria namely Neisseria mucosa, N. sicca, Branhamella catarrhalis, Klebsiella ozaenae, Citrobacterintermedius, Pseudomonas fluorescens and Enterobacter aerogenes were isolated. Gram-positive bacteria were of Bacillus subtilis, B. megaterium and Micrococcus luteus. When plasmid curing was done using acredine orange, the resistance against penicillin-G, ampicillin, tetracycline, amoxycillin, kanamycin, and chloramphenicol were totally lost in all strains, which confirmed the role of plasmid in these strains against antibiotics. Ten strains belong to different species were selected for the plasmid isolation and electrophoresis was done. Presence of plasmids in all strains was confirmed and the molecular weight was in the range of 2850 to 3170 bp. The study revealed that MAR strains are common in Uppanar estuary and they are plasmid mediated. This environment is seemed to be deteriorating at an alarming rate. PMID:18380085

Thavasi, R; Aparnadevi, K; Jayalakshmi, S; Balasubramanian, T

2007-07-01

246

Comparative Surveillance Study of Telavancin Activity against Recently Collected Gram-Positive Clinical Isolates from across the United States  

Microsoft Academic Search

Telavancin is an investigational, rapidly bactericidal lipoglycopeptide antibiotic that is being developed to treat serious infections caused by gram-positive bacteria. A baseline prospective surveillance study was conducted to assess telavancin activity, in comparison with other agents, against contemporary clinical isolates collected from 2004 to 2005 from across the United States. Nearly 4,000 isolates were collected, including staphylococci, enterococci, and streptococci

Deborah C. Draghi; Bret M. Benton; Kevin M. Krause; Clyde Thornsberry; Chris Pillar; Daniel F. Sahm

2008-01-01

247

Introduction of Bacteria In ovo.  

National Technical Information Service (NTIS)

A method and apparatus for introducing probiotic bacteria into the digestive tract of a bird in order to exclude undesirable bacteria therefrom, and inoculated eggs produced thereby, are disclosed. In a preferred embodiment of the invention, a fertile bir...

N. A. Cox J. S. Bailey

1989-01-01

248

The complete genome sequence of the Gram-positive bacterium Bacillus subtilis  

Microsoft Academic Search

Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been greatly expanded by gene duplication, the largest family containing 77 putative ATP-binding transport proteins. In addition, a large

F. Kunst; N. Ogasawara; I. Moszer; A. M. Albertini; G. Alloni; V. Azevedo; M. G. Bertero; P. Bessières; A. Bolotin; S. Borchert; R. Borriss; L. Boursier; A. Brans; M. Braun; S. C. Brignell; S. Bron; S. Brouillet; C. V. Bruschi; B. Caldwell; V. Capuano; N. M. Carter; S.-K. Choi; J.-J. Codani; I. F. Connerton; N. J. Cummings; R. A. Daniel; F. Denizot; K. M. Devine; A. Düsterhöft; S. D. Ehrlich; P. T. Emmerson; K. D. Entian; J. Errington; C. Fabret; E. Ferrari; D. Foulger; C. Fritz; M. Fujita; Y. Fujita; S. Fuma; A. Galizzi; N. Galleron; S.-Y. Ghim; P. Glaser; A. Goffeau; E. J. Golightly; G. Grandi; G. Guiseppi; B. J. Guy; K. Haga; J. Haiech; C. R. Harwood; A. Hénaut; H. Hilbert; S. Holsappel; S. Hosono; M.-F. Hullo; M. Itaya; L. Jones; B. Joris; D. Karamata; Y. Kasahara; M. Klaerr-Blanchard; C. Klein; Y. Kobayashi; P. Koetter; G. Koningstein; S. Krogh; M. Kumano; K. Kurita; A. Lapidus; S. Lardinois; J. Lauber; V. Lazarevic; S.-M. Lee; A. Levine; H. Liu; S. Masuda; C. Mauël; C. Médigue; N. Medina; R. P. Mellado; M. Mizuno; D. Moestl; S. Nakai; M. Noback; D. Noone; M. O'Reilly; K. Ogawa; A. Ogiwara; B. Oudega; S.-H. Park; V. Parro; T. M. Pohl; D. Portetelle; S. Porwollik; A. M. Prescott; E. Presecan; P. Pujic; B. Purnelle; G. Rapoport; M. Rieger; S. Reynolds; C. Rivolta; E. Rocha; B. Roche; M. Rose; Y. Sadaie; T. Sato; E. Scanlan; S. Schleich; R. Schroeter; F. Scoffone; J. Sekiguchi; A. Sekowska; S. J. Seror; P. Serror; B.-S. Shin; B. Soldo; A. Sorokin; E. Tacconi; T. Takagi; H. Takahashi; K. Takemaru; M. Takeuchi; A. Tamakoshi; T. Tanaka; P. Terpstra; A. Tognoni; V. Tosato; S. Uchiyama; M. Vandenbol; F. Vannier; A. Vassarotti; A. Viari; R. Wambutt; E. Wedler; H. Wedler; T. Weitzenegger; P. Winters; A. Wipat; H. Yamamoto; K. Yamane; K. Yasumoto; K. Yata; K. Yoshida; H.-F. Yoshikawa; E. Zumstein; H. Yoshikawa; A. Danchin

1997-01-01

249

Isolation and Characterization of Four Gram-Positive Nickel-Tolerant Microorganisms from Contaminated Sediments  

Microsoft Academic Search

Microbial communities from riparian sediments contaminated with high levels of Ni and U were examined for metal-tolerant microorganisms.\\u000a Isolation of four aerobic Ni-tolerant, Gram-positive heterotrophic bacteria indicated selection pressure from Ni. These isolates\\u000a were identified as Arthrobacter oxydans NR-1, Streptomyces galbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatospora cystarginea NR-4 based on partial 16S rDNA sequences. A functional gene microarray containing

Joy D. Van Nostrand; Tatiana V. Khijniak; Terry J. Gentry; Michelle T. Novak; Andrew G. Sowder; Jizhong Z. Zhou; Paul M. Bertsch; Pamela J. Morris

2007-01-01

250

Teichoic acids and related cell-wall glycopolymers in Gram-positive physiology and host interactions  

Microsoft Academic Search

Abstract | Most Gram-positive bacteria incorporate membrane- or peptidoglycan-attached carbohydrate-based polymers into their cell envelopes. Such cell-wall glycopolymers (CWGs) often have highly variable structures and have crucial roles in protecting, connecting and controlling the major envelope constituents. Further important roles of CWGs in host-cell adhesion, inflammation and immune activation have also been described in recent years. Identifying and harnessing highly

Christopher Weidenmaier; Andreas Peschel

2008-01-01

251

Progress in the Development of Effective Vaccines to Prevent Selected Gram Positive Bacterial Infections  

PubMed Central

Infections due to virulent gram positive bacteria, such as Staphylococcus aureus, group B streptococci and group A streptococci remain significant causes of morbidity and mortality despite progress in antimicrobial therapy. Despite significant advances in the understanding of the pathogenesis of infection due to these organisms, there are only limited strategies to prevent infection. In this paper, we review efforts to develop safe and effective vaccines that would prevent infections due to these 3 pathogens.

Bronze, Michael S.; Dale, James B.

2010-01-01

252

The complete genome sequence of the gram-positive bacterium Bacillus subtilis  

Microsoft Academic Search

Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been greatly expanded by gene duplication, the largest family containing 77 putative ATP-binding transport proteins. In addition, a large

F. Kunst; N. Ogasawara; I. Moszer; A. M. Albertini; G. Alloni; V. Azevedo; M. G. Bertero; P. Bessières; A. Bolotin; S. Borchert; R. Borriss; L. Boursier; A. Brans; M. Braun; S. C. Brignell; S. Bron; S. Brouillet; C. V. Bruschi; B. Caldwell; V. Capuano; N. M. Carter; S.-K. Choi; J.-J. Codani; I. F. Connerton; A. Danchin

1997-01-01

253

Proteolytic activity of sourdough bacteria  

Microsoft Academic Search

Proteolytic activity during the fermentation of sourdough results in an increase in amino acid content. The proteolysis is caused by flour enzymes, microbial enzymes of flour and by sourdough bacteria. The results indicate that the lactic acid bacteria of sourdough are important for proteolytic activity during the fermentation of sourdough. This proteolytic activity depends on the species of bacteria. Homo-

Gottfried Spicher; Werner Nierle

1988-01-01

254

Platelet and Neutrophil Responses to Gram Positive Pathogens in Patients with Bacteremic Infection  

PubMed Central

Background Many Gram-positive pathogens aggregate and activate platelets in vitro and this has been proposed to contribute to virulence. Platelets can also form complexes with neutrophils but little is however known about platelet and platelet-neutrophil responses in bacterial infection. Methodology/Principal Findings We added isolates of Gram-positive bacteria from 38 patients with a bacteremic infection to blood drawn from the same patient. Aggregometry and flow cytometry were used to assess platelet aggregation and to quantify activation of platelets, neutrophils, and platelet-neutrophils complexes (PNCs) induced by the bacteria. Fifteen healthy persons served as controls. Most isolates of Staphylococcus aureus, beta hemolytic streptococci, and Enterococcus faecalis induced aggregation of platelets from their respective hosts, whereas pneumococci failed to do so. S. aureus isolates induced platelet aggregation more rapidly in patients than in controls, whereas platelet activation by S. aureus was lower in patients than in controls. PNCs were more abundant in baseline samples from patients than in healthy controls and most bacterial isolates induced additional PNC formation and neutrophil activation. Conclusion/Significance We have demonstrated for the first time that bacteria isolated from patients with Gram-positive bacteremia can induce platelet activation and aggregation, PNC formation, and neutrophil activation in the same infected host. This underlines the significance of these interactions during infection, which could be a target for future therapies in sepsis.

Johansson, Daniel; Shannon, Oonagh; Rasmussen, Magnus

2011-01-01

255

Manufacture of Probiotic Bacteria  

NASA Astrophysics Data System (ADS)

Lactic acid bacteria (LAB) have been used for many years as natural biopreservatives in fermented foods. A small group of LAB are also believed to have beneficial health effects on the host, so called probiotic bacteria. Probiotics have emerged from the niche industry from Asia into European and American markets. Functional foods are one of the fastest growing markets today, with estimated growth to 20 billion dollars worldwide by 2010 (GIA, 2008). The increasing demand for probiotics and the new food markets where probiotics are introduced, challenges the industry to produce high quantities of probiotic cultures in a viable and stable form. Dried concentrated probiotic cultures are the most convenient form for incorporation into functional foods, given the ease of storage, handling and transport, especially for shelf-stable functional products. This chapter will discuss various aspects of the challenges associated with the manufacturing of probiotic cultures.

Muller, J. A.; Ross, R. P.; Fitzgerald, G. F.; Stanton, C.

256

Lipoprotein sorting in bacteria.  

PubMed

Bacterial lipoproteins are synthesized as precursors in the cytoplasm and processed into mature forms on the cytoplasmic membrane. A lipid moiety attached to the N terminus anchors these proteins to the membrane surface. Many bacteria are predicted to express more than 100 lipoproteins, which play diverse functions on the cell surface. The Lol system, composed of five proteins, catalyzes the localization of Escherichia coli lipoproteins to the outer membrane. Some lipoproteins play vital roles in the sorting of other lipoproteins, lipopolysaccharides, and ?-barrel proteins to the outer membrane. On the basis of results from biochemical, genetic, and structural studies, we discuss the biogenesis of lipoproteins in bacteria, their importance in cellular functions, and the molecular mechanisms underlying efficient sorting of hydrophobic lipoproteins to the outer membrane through the hydrophilic periplasm. PMID:21663440

Okuda, Suguru; Tokuda, Hajime

2011-01-01

257

Antibacterial Activity of Some Lactic Acid Bacteria Isolated from an Algerian Dairy Product  

PubMed Central

In the present study, the antibacterial effect of 20 lactic acid bacteria isolates from a traditional cheese was investigated. 6 isolates showed antibacterial effect against Gram positive bacteria. Streptococcus thermophilus T2 strain showed the wide inhibitory spectrum against the Gram positive bacteria. Growth and bacteriocin production profiles showed that the maximal bacteriocin production, by S. thermophilus T2 cells, was measured by the end of the late-log phase (90 AU ml?1) with a bacteriocine production rate of 9.3 (AU ml?1) h?1. In addition, our findings showed that the bacteriocin, produced by S. thermophilus T2, was stable over a wide pH range (4–8); this indicates that such bacteriocin may be useful in acidic as well as nonacidic food. This preliminarily work shows the potential application of autochthonous lactic acid bacteria to improve safety of traditional fermented food.

Mezaini, Abdelkader; Chihib, Nour-Eddine; Dilmi Bouras, Abdelkader; Nedjar-Arroume, Naima; Hornez, Jean Pierre

2009-01-01

258

Filamentous Phage Active on the Gram-Positive Bacterium Propionibacterium freudenreichii  

PubMed Central

We present the first description of a single-stranded DNA filamentous phage able to replicate in a gram-positive bacterium. Phage B5 infects Propionibacterium freudenreichii and has a genome consisting of 5,806 bases coding for 10 putative open reading frames. The organization of the genome is very similar to the organization of the genomes of filamentous phages active on gram-negative bacteria. The putative coat protein exhibits homology with the coat proteins of phages PH75 and Pf3 active on Thermus thermophilus and Pseudomonas aeruginosa, respectively. B5 is, therefore, evolutionarily related to the filamentous phages active on gram-negative bacteria.

Chopin, Marie-Christine; Rouault, Annette; Ehrlich, S. Dusko; Gautier, Michel

2002-01-01

259

Extracellular metalloproteases from bacteria  

Microsoft Academic Search

Bacterial extracellular metalloproteases (BEMPs) are a large group of metal-containing proteases secreted by heterotrophic\\u000a bacteria. In this review, the diversity, structural characteristics, mechanisms of maturation, physiological roles, and applications\\u000a of BEMPs are described. BEMPs are distributed among nine families of metalloproteases because of differences in primary sequences\\u000a and structural characteristics. Until now, all of the BEMPs identified have been endoproteases

Ji-Wei Wu; Xiu-Lan Chen

260

Bacteria in Confined Spaces  

NASA Astrophysics Data System (ADS)

Bacterial cells can display differentiation between several developmental pathways, from planktonic to matrix-producing, depending upon the colony conditions. We study the confinement of bacteria in hydrogels as well as in liquid-liquid double emulsion droplets and observe the growth and morphology of these colonies as a function of time and environment. Our results can give insight into the behavior of bacterial colonies in confined spaces that can have applications in the areas of food science, cosmetics, and medicine.

Wilking, Connie; Weitz, David

2010-03-01

261

Bacteria: More Than Pathogens  

NSDL National Science Digital Library

This ActionBioscience lesson plan has students explore the many roles of bacteria, harmful and beneficial. A detailed article written for ActionBioscience by a microbiologist provides background information, which is followed by discussion questions and educational activities designed for middle school to undergraduate biology courses. The Web site also provides carefully selected links for further exploring the topic, including useful sites for student research projects.

Wassenaar, Trudy M.

262

Cheek Cells and Bacteria  

NSDL National Science Digital Library

Dr. Brett Finlay enlists a student volunteer to show the surprisingly high amount of bacteria found in his own mouth. This resource is also featured on the DVD 2000 and Beyond: Confronting the Microbe Menace, available free from HHMI. This video is one minute and 27 seconds in length, and available in MOV (8 MB) and WMV (12 MB). All Infectious Disease videos are located at: http://www.hhmi.org/biointeractive/disease/video.html.

Dr. Brett Finlay (Howard Hughes Medical Institute;)

2007-03-27

263

Glacial lake hides bacteria  

NSDL National Science Digital Library

This article highlights the published work of a geomicrobiology research team led by Eric Gaidos from the University of Hawaii and Brian Lanoil, from the University of California, Riverside. This group reports the identification of bacteria from an Icelandic sub-glacial lake, and how the collection and description of these microorganisms immured within glacial ice and sub-surface water serve as a model in the search for extra-terrestrial life.

Peplow, Mark; Online, Bioed

264

Phenotypic and phylogenetic characterization of ruminal tannin-tolerant bacteria.  

PubMed

The 16S rRNA sequences and selected phenotypic characteristics were determined for six recently isolated bacteria that can tolerate high levels of hydrolyzable and condensed tannins. Bacteria were isolated from the ruminal contents of animals in different geographic locations, including Sardinian sheep (Ovis aries), Honduran and Colombian goats (Capra hircus), white-tail deer (Odocoileus virginianus) from upstate New York, and Rocky Mountain elk (Cervus elaphus nelsoni) from Oregon. Nearly complete sequences of the small-subunit rRNA genes, which were obtained by PCR amplification, cloning, and sequencing, were used for phylogenetic characterization. Comparisons of the 16S rRNA of the six isolates showed that four of the isolates were members of the genus Streptococcus and were most closely related to ruminal strains of Streptococcus bovis and the recently described organism Streptococcus gallolyticus. One of the other isolates, a gram-positive rod, clustered with the clostridia in the low-G+C-content group of gram-positive bacteria. The sixth isolate, a gram-negative rod, was a member of the family Enterobacteriaceae in the gamma subdivision of the class Proteobacteria. None of the 16S rRNA sequences of the tannin-tolerant bacteria examined was identical to the sequence of any previously described microorganism or to the sequence of any of the other organisms examined in this study. Three phylogenetically distinct groups of ruminal bacteria were isolated from four species of ruminants in Europe, North America, and South America. The presence of tannin-tolerant bacteria is not restricted by climate, geography, or host animal, although attempts to isolate tannin-tolerant bacteria from cows on low-tannin diets failed. PMID:9758806

Nelson, K E; Thonney, M L; Woolston, T K; Zinder, S H; Pell, A N

1998-10-01

265

Phylogenetic analysis of anaerobic thermophilic bacteria: aid for their reclassification.  

PubMed Central

Small subunit rDNA sequences were determined for 20 species of the genera Acetogenium, Clostridium, Thermoanaerobacter, Thermoanaerobacterium, Thermoanaerobium, and Thermobacteroides, 3 non-validly described species, and 5 isolates of anaerobic thermophilic bacteria, providing a basis for a phylogenetic analysis of these organisms. Several species contain a version of the molecule significantly longer than that of Escherichia coli because of the presence of inserts. On the basis of normal evolutionary distances, the phylogenetic tree indicates that all bacteria investigated in this study with a maximum growth temperature above 65 degrees C form a supercluster within the subphylum of gram-positive bacteria that also contains Clostridium thermosaccharolyticum and Clostridium thermoaceticum, which have been previously sequenced. This supercluster appears to be equivalent in its phylogenetic depth to the supercluster of mesophilic clostridia and their nonspore-forming relatives. Several phylogenetically and phenotypically coherent clusters that are defined by sets of signature nucleotides emerge within the supercluster of thermophiles. Clostridium thermobutyricum and Clostridium thermopalmarium are members of Clostridium group I. A phylogenetic tree derived from transversion distances demonstrated the artificial clustering of some organisms with high rDNA G+C moles percent, i.e., Clostridium fervidus and the thermophilic, cellulolytic members of the genus Clostridium. The results of this study can be used as an aid for future taxonomic restructuring of anaerobic sporogenous and asporogenous thermophillic, gram-positive bacteria.

Rainey, F A; Ward, N L; Morgan, H W; Toalster, R; Stackebrandt, E

1993-01-01

266

Antibiotic Resistant Bacteria  

NSDL National Science Digital Library

This week's Topic In Depth is about antibiotic resistant bacteria.The first site is a recent news report from BBC news (1) that describes some recent research on resistant strains of two "of the world's most dangerous bacteria. Next is a Centers for Disease Control (CDC) page (2) with a brief background on antibiotic resistance and how to prevent it. A much more in-depth report is provided by the Select Committee on Science and Technology of the British House of Lords (3). There has been some public concern over the use of antibiotic resistant bacteria strains as markers in genetically modified food crops. The next two resources present information specific to this topic. The first is from the European Federation of Biotechnology (4), and the second is a shorter report from the Council for Biotechnology Information (5). The Alliance for the Prudent Use of Antibiotics (6) has a consumer and patient information section that explains what individuals can do to help prevent the problem from increasing. Readers who need a brief primer on antibiotics may appreciate this Web site from the University of Edinburgh (7). The last site is a "bugs in the news" feature from the University of Kansas (8), which is an easy-to-read explanation of "what the heck" antibiotic resistance is.

Lee, Amy.

2002-01-01

267

Siboglinid-bacteria endosymbiosis  

PubMed Central

Siboglinid worms are a group of gutless marine annelids which are nutritionally dependent upon endosymbiotic bacteria.1,2 Four major groups of siboglinids are known including vestimentiferans, Osedax spp., frenulates and moniliferans.3–5 Very little is known about the diversity of bacterial endosymbionts associated with frenulate or monoliferan siboglinids. This lack of knowledge is surprising considering the global distribution of siboglinids; this system is likely among the most common symbioses in the deep sea. At least three distinct clades of endosymbiotic ?-proteobacteria associate with siboglinid annelids.6 Frenulates harbor a clade of ?-proteobacteria that are divergent from both the thiotrophic bacteria of vestimentiferans and monoliferans as well as the heterotrophic bacteria of Osedax spp.6,7 We also discuss priorities for future siboglinid research and the need to move beyond descriptive studies. A promising new method, laser-capture microdissection (LCM), allows for the precise excision of tissue regions of interest.8 This method, when used in concert with molecular and genomic techniques, such as Expressed Sequence Tag (EST) surveys using pyrosequencing technology, will likely enable investigations into physiological processes and mechanisms in these symbioses. Furthermore, adopting a comparative approach using different siboglinid groups, such as worms harboring thiotrophic versus methanotrophic endosymbionts, may yield considerable insight into the ecology and evolution of the Siboglinidae.

Fielman, Kevin T; Santos, Scott R; Halanych, Kenneth M

2008-01-01

268

[Bacteria isolated from surgical infections and their susceptibilities to antimicrobial agents --special references to bacteria isolated between April 2008 and March 2009].  

PubMed

Bacteria isolated from infections in abdominal surgery during the period from April 2008 to March 2009 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, 712 strains including 18 strains of Candida spp. were isolated from 173 (80.5%) of 215 patients with surgical infections. Three hundred and sixty-six strains were isolated from primary infections, and 346 strains were isolated from postoperative infections. From primary infections, anaerobic Gram-negative bacteria were predominant, followed by aerobic Gram-negative bacteria, while from postoperative infections aerobic Gram-positive bacteria were predominant, followed by anaerobic Gram-negative bacteria. Among aerobic Gram-positive bacteria, the isolation rate of Enterococcus spp. was highest, followed by Streptococcus spp., and Staphylococcus spp. in this order, from primary infections, while Enterococcus spp. was highest, followed by Staphylococcus spp. from postoperative infections. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Klebsiella pneumoniae and Pseudomonas aeruginosa, in this order, and from postoperative infections, P aeruginosa was most predominantly isolated, followed by E. coli, Enterobacter cloacae, and K. pneumoniae. Among anaerobic Gram-positive bacteria, the isolation rate of Eggerthella lenta was the highest from primary infections, followed by Parvimonas micra, Streptococcus constellatus and Gemella morbillorum, and from postoperative infections, E. lenta was most predominantly isolated. Among anaerobic Gram-negative bacteria, the isolation rate of Bacteroides fragilis was the highest from primary infections, followed by Bacteroides thetaiotaomicron, Bacteroides ovatus and Bilophila wadsworthia, and from postoperative infections, B. fragilis was most predominantly isolated, followed by B. thetaiotaomicron, B. wadsworthia and B. ovatus, in this order. In this series, we noticed no vancomycin-resistant methicillin-resistant S. aureus, and Enterococcus spp., nor multidrug-resistant P aeruginosa. We should carefully follow up B. wadsworthia which was resistant to various antibiotics, and also Bacteroides spp. which was resistant to many beta-lactam antibiotics. PMID:20919496

Shinagawa, Nagao; Hasegawa, Masamitsu; Hirata, Koichi; Furuhata, Tomohisa; Mizukuchi, Tohru; Osanai, Hiroyuki; Yanai, Yoshiyuki; Hata, Fumitaka; Sasaki, Kazuaki; Someya, Tetsufumi; Harada, Keisuke; Oono, Keisuke; Tokita, Shoji; Nakamura, Masashi; Shibuya, Hitoshi; Hasegawa, Itaru; Kimura, Masami; Oshima, Hideki; Maeda, Hideki; Mukaiya, Mitsuhiro; Kihara, Chikasi; Kosho, Watabe; Hoshikawa, Tsuyoshi; Kimura, Hitoshi; Ushijima, Yasuhide; Yae-Hoon, Yoo; Aikawa, Naoki; Abe, Shinya; Yura, Jiro; Takeyama, Hiromitsu; Wakasugi, Takehiro; Taniguchi, Masaaki; Mizuno, Isamu; Fukui, Takuji; Mashita, Keiji; Ishikawa, Svu; Mizuno, Akira; Moori, Noriaki; Sumita, Naoki; Kubo, Shoji; Lee, Shigeruj; Oomura, Toru; Kobayashi, Yasuhito; Tsuji, Takeshi; Yamaue, Hiroki; Kawai, Manabu; Takesue, Yoshio; Tanaka, Noriaki; Kimura, Hideyuki; Iwagaki, Hiromi; Sueda, Taijiro; Hiyama, Eiso; Murakami, Yoshiaki; Ooge, Hiroki; Uemura, Kenichiro; Tsumura, Hiroaki; Yokoyama, Takashi; Takeuchi, Hitoshi; Tanakaya, Kouji; Yasunami, Yoichi; Ryu, Shinichiro

2010-04-01

269

Pepsin homologues in bacteria  

PubMed Central

Background Peptidase family A1, to which pepsin belongs, had been assumed to be restricted to eukaryotes. The tertiary structure of pepsin shows two lobes with similar folds and it has been suggested that the gene has arisen from an ancient duplication and fusion event. The only sequence similarity between the lobes is restricted to the motif around the active site aspartate and a hydrophobic-hydrophobic-Gly motif. Together, these contribute to an essential structural feature known as a psi-loop. There is one such psi-loop in each lobe, and so each lobe presents an active Asp. The human immunodeficiency virus peptidase, retropepsin, from peptidase family A2 also has a similar fold but consists of one lobe only and has to dimerize to be active. All known members of family A1 show the bilobed structure, but it is unclear if the ancestor of family A1 was similar to an A2 peptidase, or if the ancestral retropepsin was derived from a half-pepsin gene. The presence of a pepsin homologue in a prokaryote might give insights into the evolution of the pepsin family. Results Homologues of the aspartic peptidase pepsin have been found in the completed genomic sequences from seven species of bacteria. The bacterial homologues, unlike those from eukaryotes, do not possess signal peptides, and would therefore be intracellular acting at neutral pH. The bacterial homologues have Thr218 replaced by Asp, a change which in renin has been shown to confer activity at neutral pH. No pepsin homologues could be detected in any archaean genome. Conclusion The peptidase family A1 is found in some species of bacteria as well as eukaryotes. The bacterial homologues fall into two groups, one from oceanic bacteria and one from plant symbionts. The bacterial homologues are all predicted to be intracellular proteins, unlike the eukaryotic enzymes. The bacterial homologues are bilobed like pepsin, implying that if no horizontal gene transfer has occurred the duplication and fusion event might be very ancient indeed, preceding the divergence of bacteria and eukaryotes. It is unclear whether all the bacterial homologues are derived from horizontal gene transfer, but those from the plant symbionts probably are. The homologues from oceanic bacteria are most closely related to memapsins (or BACE-1 and BACE-2), but are so divergent that they are close to the root of the phylogenetic tree and to the division of the A1 family into two subfamilies.

Rawlings, Neil D; Bateman, Alex

2009-01-01

270

Insulator-based dielectrophoresis for the selective concentration and separation of live bacteria in water  

Microsoft Academic Search

Insulator-based dielectrophoresis (iDEP) was utilized to separate and concentrate selectively mixtures of two species of live bacteria simultaneously. Four species of bacteria were studied: the Gram-negative Escherichia coli and the Gram-positive Bacillus subtilis, B. cereus, and B. megaterium. Under an applied direct current (DC) electric field all the bacterial species exhibited negative dielectrophoretic behavior. The dielectrophoretic separations were carried out

Blanca H. Lapizco-Encinas; Blake A. Simmons; Eric B. Cummings; Yolanda Fintschenko

2004-01-01

271

Genetic diversity of culturable bacteria in oil-contaminated rhizosphere of Galega orientalis  

Microsoft Academic Search

A collection of 50 indigenous meta-toluate tolerating bacteria isolated from oil-contaminated rhizosphere of Galega orientalis on selective medium was characterized and identified by classical and molecular methods. 16S rDNA partial sequencing showed the presence of five major lineages of the Bacteria domain. Gram-positive Rhodococcus, Bacillus and Arthrobacter and gram-negative Pseudomonas were the most abundant genera. Only one-fifth of the strains

Minna M. Jussila; German Jurgens; Kristina Lindstrom; Leena Suominen

272

Characterization of anti-listerial lactic acid bacteria isolated from Thai fermented fish products  

Microsoft Academic Search

Thai fermented fish products were screened for lactic acid bacteria capable of inhibitingListeriasp. (Listeria innocua). Of 4150 assumed lactic acid bacteria colonies from MRS agar plates that were screened by an agar-overlay method 58 (1.4%) were positive. Forty four of these strains were further characterized and 43 strains were inhibitory againstListeria monocytogenes. The strains were inhibitory to other Gram-positive (lactic

A. Østergaard; P. K. B. Embarek; C. Wedell-Neergaard; H. H. Huss; L. Gram

1998-01-01

273

COMPARATIVE STUDY OF TWO BACTERIOCINS PRODUCED BY REPRESENTATIVE INDIGENOUS SOIL BACTERIA  

Microsoft Academic Search

The aim of this research work was to identify and characterized the bacteriocins produced by soil-associated bacteria. Bacillocin from Bacillus brevis Bb and pyocin from Pseudomonas aeruginosa Pa were found bioactive only against gram-positive bacteria tested. Maximum production of both the bacteriocins was observed at 32°C in BHI medium. Production of both the bacteriocins started in the early exponential growth

FARAH SALEEM; SAMIA AHMAD; ZOBIA YAQOOB; SHEIKH AJAZ RASOOL

274

The Drosophila immune response against Gram-negative bacteria is mediated by a peptidoglycan recognition protein  

Microsoft Academic Search

The antimicrobial defence of Drosophila relies largely on the challenge-induced synthesis of an array of potent antimicrobial peptides by the fat body. The defence against Gram-positive bacteria and natural fungal infections is mediated by the Toll signalling pathway, whereas defence against Gram-negative bacteria is dependent on the Immune deficiency (IMD) pathway. Loss-of-function mutations in either pathway reduce the resistance to

Marie Gottar; Vanessa Gobert; Tatiana Michel; Marcia Belvin; Geoffrey Duyk; Jules A. Hoffmann; Dominique Ferrandon; Julien Royet

2002-01-01

275

Direct Application of the Polymerase Chain Reaction for Quantification of Total Bacteria on Fish Fillets  

Microsoft Academic Search

A rapid, conventional PCR assay that quantifies total bacteria from fish fillets is described. The methodology is based on the use of the universal primers DG74 and RW01 to amplify a 370-bp conserved sequence of the 16S rRNA gene of Gram-positive and Gram-negative bacteria. The intensity of amplified DNA bands (from mixed bacterial flora of fish fillets) in agarose gels

Jung-Lim Lee; Robert E. Levin

2006-01-01

276

The proteolytic system of lactic acid bacteria revisited: a genomic comparison  

Microsoft Academic Search

BACKGROUND: Lactic acid bacteria (LAB) are a group of gram-positive, lactic acid producing Firmicutes. They have been extensively used in food fermentations, including the production of various dairy products. The proteolytic system of LAB converts proteins to peptides and then to amino acids, which is essential for bacterial growth and also contributes significantly to flavor compounds as end-products. Recent developments

Mengjin Liu; Jumamurat R Bayjanov; Bernadet Renckens; Arjen Nauta; Roland J Siezen

2010-01-01

277

Mastitis: I. In Vitro Antimicrobial Activity of Alkyl Amines Against Mastitic Bacteria  

Microsoft Academic Search

The activities of branched and straight chain amines (10 to 18 carbons chain length) were compared in inhibiting the growth of five microorganisms that cause about 95% of bovine mastitis. Three gram-positive (Streptococcus aga- lactiae, Streptococcus uberis, Staphylo- coccus aureus) and two gram-negative (Eschericbia coli, Klebsiella pneumoniae) bacteria were used in a trypticase soy broth tube culture growth assay. Sixty-

M. D. Culler; J. Bitman; M. J. Thompson; W. E. Robbins; S. R. Dutky

1979-01-01

278

Isolation and Characterization of Endophytic Colonizing Bacteria from Agronomic Crops and Prairie Plants  

Microsoft Academic Search

Endophytic bacteria reside within plant hosts without causing disease symptoms. In this study, 853 endophytic strains were isolated from aerial tissues of four agronomic crop species and 27 prairie plant species. We determined several phenotypic properties and found approximately equal numbers of gram-negative and gram-positive isolates. In a greenhouse study, 28 of 86 prairie plant endophytes were found to colonize

Denise K. Zinniel; Patricia A. Lambrecht; N. Beth Harris; Zhengyu Feng; Daniel Kuczmarski; Phyllis Higley; Carol A. Ishimaru; Alahari Arunakumari; Raul G. Barletta; Anne M. Vidaver

2002-01-01

279

Evaluation of the Sceptor system for identification of bacteria of veterinary origin.  

PubMed Central

The Sceptor system (Becton Dickinson Diagnostic Instrument Systems, Towson Md.) was assessed for its ability to identify veterinary clinical isolates. A total of 605 bacteria, including 315 isolates of the family Enterobacteriaceae, 191 gram-negative nonenteric bacteria, and 99 gram-positive bacteria, were tested. Overall, 534 (88.3%) were correctly identified, 28 (4.6%) were not identified, 12 (2.0%) were incorrectly identified at the genus levels, and 32 (5.3%) were incorrectly identified at the species level. The Sceptor system correctly identified 292 (92.7%) isolates of Enterobacteriaceae, 165 (86.4%) gram-negative nonenteric bacteria, and 77 (77.8%) gram-positive bacteria. One hundred thirty organisms not contained in the data base were tested with the Sceptor system to assess the possibility of expanding the data base. The Sceptor system was an acceptable method for the identification of isolates of Enterobacteriaceae but not gram-negative nonenteric and gram-positive bacteria of animal origin. Development of a veterinary isolate-specific data base would improve the utility of the Sceptor system in veterinary diagnostic bacteriology.

Papp, J R; Muckle, C A

1991-01-01

280

Plasmodium falciparum: inhibition of sporogonic development in Anopheles stephensi by gram-negative bacteria.  

PubMed

We investigated the effects of bacteria on Plasmodium falciparum sporogonic development in Anopheles stephensi. Four gram-negative (Escherichia coli H243, E. coli HB101, Pseudomonas aeruginosa, and Ewingella americana) and two gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) bacterial strains were used in the study. Tenfold dilutions of bacteria suspended in phosphate-buffered saline were mixed with an infectious meal of gametocyte-enriched cultures and fed to adult mosquitoes. All gram-negative bacteria strains partially or completely inhibited oocyst formation at different concentrations. Additionally, geometric mean number of oocysts showed a correspondingly significant decrease with increasing bacterial concentration (P < 0.001). In contrast, gram-positive bacteria strains did not have any inhibitory effects on oocyst formation even at very high concentrations. Oocyst development was not affected by: (i) culture supernatants of E. americana, (ii) formalin-treated E. coli H243, (iii) lipopolysaccharide of E. coli J5 (mutant of 0111:B4). These studies show that gram-negative but not gram-positive bacteria affect sporogonic-stage development of P. falciparum in A. stephensi. Inhibition of parasite acquisition may be an attribute of specific or nonspecific cytoadherence properties of gram-negative bacteria to the parasites. PMID:8375488

Pumpuni, C B; Beier, M S; Nataro, J P; Guers, L D; Davis, J R

1993-09-01

281

Triclosan- resistant bacteria isolated from feedlot and residential soils  

PubMed Central

Triclosan is an antimicrobial agent that is currently incorporated into hundreds of consumer and medical products. It can be either a bacteriostatic or bactericidal agent, depending on its formulation. It has activity against Gram-positive and Gram-negative bacteria, as well as some viruses and protists. The purpose of this study was to determine whether triclosan-resistant bacteria could be isolated from the soil. Soils from cattle feedlots and residential lawns were collected and assayed for the presence of these organisms by plating samples on growth media containing triclosan. Organisms were subsequently identified by partial 16S rRNA sequencing analysis. All the organisms isolated in this study were Gram-negative rods, with members of genus Pseudomonas being particularly well represented. This result may not be surprising because Gram-negative organisms are generally more resistant to triclosan, and since Pseudomonas bacteria are known to have numerous efflux mechanisms for dealing with harmful substances.

WELSCH, TANNER T.; GILLOCK, ERIC T.

2014-01-01

282

Surface layers of bacteria.  

PubMed Central

Since bacteria are so small, microscopy has traditionally been used to study them as individual cells. To this end, electron microscopy has been a most powerful tool for studying bacterial surfaces; the viewing of macromolecular arrangements of some surfaces is now possible. This review compares older conventional electron-microscopic methods with new cryotechniques currently available and the results each has produced. Emphasis is not placed on the methodology but, rather, on the importance of the results in terms of our perception of the makeup and function of bacterial surfaces and their interaction with the surrounding environment. Images

Beveridge, T J; Graham, L L

1991-01-01

283

Mercury Transport in Bacteria  

Microsoft Academic Search

Mercuric ions (Hg2+) and methylmercury are major, human-generated, toxic contaminants present in fish and our waterways. Bacteria provide a means\\u000a of bioremediation by taking up these compounds and reducing them to volatile, non-toxic, elemental mercury (Hg°). Three types\\u000a of mercury\\/methylmercury transporters have previously been identified: MerC, MerF and MerT. Each of these sets of homologues\\u000a has distinct topologies. MerF proteins

Ai Yamaguchi; Dorjee G. Tamang; Milton H. Saier Jr

2007-01-01

284

Isolation and Characterization of Bacteria from Ancient Siberian Permafrost Sediment  

PubMed Central

In this study, we isolated and characterized bacterial strains from ancient (Neogene) permafrost sediment that was permanently frozen for 3.5 million years. The sampling site was located at Mammoth Mountain in the Aldan river valley in Central Yakutia in Eastern Siberia. Analysis of phospolipid fatty acids (PLFA) demonstrated the dominance of bacteria over fungi; the analysis of fatty acids specific for Gram-positive and Gram-negative bacteria revealed an approximately twofold higher amount of Gram-negative bacteria compared to Gram-positive bacteria. Direct microbial counts after natural permafrost enrichment showed the presence of (4.7 ± 1.5) × 108 cells g?1 sediment dry mass. Viable heterotrophic bacteria were found at 0 °C, 10 °C and 25 °C, but not at 37 °C. Spore-forming bacteria were not detected. Numbers of viable fungi were low and were only detected at 0 °C and 10 °C. Selected culturable bacterial isolates were identified as representatives of Arthrobacter phenanthrenivorans, Subtercola frigoramans and Glaciimonas immobilis. Representatives of each of these species were characterized with regard to their growth temperature range, their ability to grow on different media, to produce enzymes, to grow in the presence of NaCl, antibiotics, and heavy metals, and to degrade hydrocarbons. All strains could grow at ?5 °C; the upper temperature limit for growth in liquid culture was 25 °C or 30 °C. Sensitivity to rich media, antibiotics, heavy metals, and salt increased when temperature decreased (20 °C > 10 °C > 1 °C). In spite of the ligninolytic activity of some strains, no biodegradation activity was detected.

Zhang, De-Chao; Brouchkov, Anatoli; Griva, Gennady; Schinner, Franz; Margesin, Rosa

2013-01-01

285

In Vitro Evaluation of the Antibacterial Activity of Three Different Central Venous Catheters Against Gram-Positive Bacteria  

Microsoft Academic Search

.   The aim of this study was to evaluate the activity of three different catheters against Staphylococcus aureus ATCC 29213 and the slime-producing Staphylococcus epidermidis ATCC 35984 (RP62A). Three central venous catheters were evaluated: one impregnated with silver sulfadiazine–chlorhexidine,\\u000a one to which minocycline\\/rifampin is bonded and a novel one into which silver, platinum and carbon are incorporated. A nonantiseptic\\u000a catheter

K. Yorganci; C. Krepel; J. Weigelt; C. Edmiston

2002-01-01

286

Exploring 9-benzyl purines as inhibitors of glutamate racemase (MurI) in Gram-positive bacteria  

Microsoft Academic Search

An early SAR study of a screening hit series has generated a series of 9-benzyl purines as inhibitors of bacterial glutamate racemase (MurI) with micromolar enzyme potency and improved physical properties. X-ray co-crystal EI structures were obtained.

Bolin Geng; Gloria Breault; Janelle Comita-Prevoir; Randy Petrichko; Charles Eyermann; Tomas Lundqvist; Peter Doig; Elise Gorseth; Brian Noonan

2008-01-01

287

Isolation and Purification of Enterocin E-760 with Broad Antimicrobial Activity against Gram-Positive and Gram-Negative Bacteria?  

PubMed Central

Strain NRRL B-30745, isolated from chicken ceca and identified as Enterococcus durans, Enterococcus faecium, or Enterococcus hirae, was initially identified as antagonistic to Campylobacter jejuni. The isolate produced a 5,362-Da bacteriocin (enterocin) that inhibits the growth of Salmonella enterica serovar Enteritidis, S. enterica serovar Choleraesuis, S. enterica serovar Typhimurium, S. enterica serovar Gallinarum, Escherichia coli O157:H7, Yersinia enterocolitica, Citrobacter freundii, Klebsiella pneumoniae, Shigella dysenteriae, Pseudomonas aeruginosa, Proteus mirabilis, Morganella morganii, Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes, Campylobacter jejuni, and 20 other Campylobacter species isolates. The enterocin, E-760, was isolated and purified by cation-exchange and hydrophobic-interaction chromatographies. The proteinaceous nature of purified enterocin E-760 was demonstrated upon treatment with various proteolytic enzymes. Specifically, the antimicrobial peptide was found to be sensitive to beta-chymotrypsin, proteinase K, and papain, while it was resistant to lysozyme and lipase. The enterocin demonstrated thermostability by retaining activity after 5 min at 100°C and was stable at pH values between 5.0 and 8.7. However, activity was lost below pH 3.0 and above pH 9.5. Administration of enterocin E-760-treated feed significantly (P < 0.05) reduced the colonization of young broiler chicks experimentally challenged and colonized with two strains of C. jejuni by more than 8 log10 CFU. Enterocin E-760 also significantly (P < 0.05) reduced the colonization of naturally acquired Campylobacter species in market age broiler chickens when administered in treated feed 4 days prior to analysis.

Line, J. E.; Svetoch, E. A.; Eruslanov, B. V.; Perelygin, V. V.; Mitsevich, E. V.; Mitsevich, I. P.; Levchuk, V. P.; Svetoch, O. E.; Seal, B. S.; Siragusa, G. R.; Stern, N. J.

2008-01-01

288

Isolation and characterisation of new Gram-negative and Gram-positive atrazine degrading bacteria from different French soils  

Microsoft Academic Search

The capacity of 12 soils to degrade atrazine was studied in laboratory incubations using radiolabelled atrazine. Eight soils showed enhanced degradation of this compound. Twenty-five bacterial strains able to degrade atrazine were isolated by an enrichment method from 10 of these soils. These soils were chosen for their wide range of physico-chemical characteristics. Their history of treatment with atrazine was

Sandrine Rousseaux; Alain Hartmann; Guy Soulas

2001-01-01

289

Direct screening of recombinants in gram-positive bacteria using the secreted staphylococcal nuclease as a reporter.  

PubMed

A system for direct screening of recombinant clones in Lactococcus lactis, based on secretion of the staphylococcal nuclease (SNase) in the organism, was developed. The nuc gene (encoding SNase) was cloned on both rolling-circle and theta-replicating plasmids. L. lactis strains containing these nuc+ plasmids secrete SNase and are readily detectable by a simple plate test. A multicloning site (MCS) was introduced just after the cleavage site between leader peptide and the mature SNase, without affecting nuclease activity. Cloning foreign DNA fragments into any site of the MCS interrupts nuc and thus results in nuc mutant clones which are easily distinguished fron nuc+ clones on plates. The utility of this system for L. lactis was demonstrated by cloning an antibiotic resistance marker and Escherichia coli chromosomal DNA fragments into the MCS of the nucMCS cassette. Both cloning vectors containing the nucMCS cassette were also introduced into Streptococcus salivarius subsp. thermophilus, in which direct screening of nuc mutant recombinant clones was also achieved. The potential uses of nuc as a secretion reporter system are discussed. PMID:8051029

Le Loir, Y; Gruss, A; Ehrlich, S D; Langella, P

1994-08-01

290

Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria  

PubMed Central

Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10-xAgx(PO4)6(OH)2, xAg?=?0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a?=?b?=?9.435 Å, c?=?6.876 Å for xAg?=?0.05, a?=?b?=?9.443 Å, c?=?6.875 Å for xAg?=?0.2, and a?=?b?=?9.445 Å, c?=?6.877 Å for xAg?=?0.3 are in good agreement with the standard of a?=?b?=?9.418 Å, c?=?6.884 Å (space group P63/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples (xAg?=?0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of xAg in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth (P. stuartii).

2012-01-01

291

Antibacterial effect (in vitro) of Moringa oleifera and Annona muricata against Gram positive and Gram negative bacteria.  

PubMed

Antibacterial effects of aqueous and ethanolic extracts of seeds of moringa (Moringa oleifera) and pods of soursop (Annona muricata) in the concentration of 1:5 and 1:10 in volumes 50, 100, 150 and 200 microL were examined against Staphylococcus aureus, Vibrio cholerae, Escherichia coli (isolated from the organism and the aquatic environment) and Salmonella Enteritidis. Antibacterial activity (inhibition halo > 13 mm) against S. aureus, V. cholerae and E. coli isolated from the whiteleg shrimp, Litopenaeus vannmaei, was detected in aqueous and ethanolic extracts of moringa. E. coli isolated from tilapiafish, Oreochromis niloticus, was sensitive to the ethanolic extract of moringa. The aqueous extracts of soursop showed an antibacterial effect against S. aureus and V. cholerae, but the antibacterial activity by the ethanol extracts of this plant was not demonstrated. PMID:20602021

Viera, Gustavo Hitzschky Fernandes; Mourão, Jozeanne Alves; Angelo, Angela Maria; Costa, Renata Albuquerque; Vieira, Regine Helena Silva dos Fernandes

2010-01-01

292

Designing surfaces that kill bacteria on contact  

NASA Astrophysics Data System (ADS)

Poly(4-vinyl-N-alkylpyridinium bromide) was covalently attached to glass slides to create a surface that kills airborne bacteria on contact. The antibacterial properties were assessed by spraying aqueous suspensions of bacterial cells on the surface, followed by air drying and counting the number of cells remaining viable (i.e., capable of growing colonies). Amino glass slides were acylated with acryloyl chloride, copolymerized with 4-vinylpyridine, and N-alkylated with different alkyl bromides (from propyl to hexadecyl). The resultant surfaces, depending on the alkyl group, were able to kill up to 94 ± 4% of Staphylococcus aureus cells sprayed on them. A surface alternatively created by attaching poly(4-vinylpyridine) to a glass slide and alkylating it with hexyl bromide killed 94 ± 3% of the deposited S. aureus cells. On surfaces modified with N-hexylated poly(4-vinylpyridine), the numbers of viable cells of another Gram-positive bacterium, Staphylococcus epidermidis, as well as of the Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli, dropped more than 100-fold compared with the original amino glass. In contrast, the number of viable bacterial cells did not decline significantly after spraying on such common materials as ceramics, plastics, metals, and wood.

Tiller, Joerg C.; Liao, Chun-Jen; Lewis, Kim; Klibanov, Alexander M.

2001-05-01

293

Programmed Death in Bacteria  

PubMed Central

Programmed cell death (PCD) in bacteria plays an important role in developmental processes, such as lysis of the mother cell during sporulation of Bacillus subtilis and lysis of vegetative cells in fruiting body formation of Myxococcus xanthus. The signal transduction pathway leading to autolysis of the mother cell includes the terminal sporulation sigma factor E?K, which induces the synthesis of autolysins CwlC and CwlH. An activator of autolysin in this and other PCD processes is yet to be identified. Autolysis plays a role in genetic exchange in Streptococcus pneumoniae, and the gene for the major autolysin, lytA, is located in the same operon with recA. DNA from lysed cells is picked up by their neighbors and recombined into the chromosome by RecA. LytA requires an unknown activator controlled by a sensory kinase, VncS. Deletion of vncS inhibits autolysis and also decreases killing by unrelated antibiotics. This observation suggests that PCD in bacteria serves to eliminate damaged cells, similar to apoptosis of defective cells in metazoa. The presence of genes affecting survival without changing growth sensitivity to antibiotics (vncS, lytA, hipAB, sulA, and mar) indicates that bacteria are able to control their fate. Elimination of defective cells could limit the spread of a viral infection and donate nutrients to healthy kin cells. An altruistic suicide would be challenged by the appearance of asocial mutants without PCD and by the possibility of maladaptive total suicide in response to a uniformly present lethal factor or nutrient depletion. It is proposed that a low rate of mutation serves to decrease the probability that asocial mutants without PCD will take over the population. It is suggested that PCD is disabled in persistors, rare cells that are resistant to killing, to ensure population survival. It is suggested that lack of nutrients leads to the stringent response that suppresses PCD, producing a state of tolerance to antibiotics, allowing cells to discriminate between nutrient deprivation and unrepairable damage. High levels of persistors are apparently responsible for the extraordinary survival properties of bacterial biofilms, and genes affecting persistence appear to be promising targets for development of drugs aimed at eradicating recalcitrant infections. PCD in unicellular eukaryotes is also considered, including aging in Saccharomyces cerevisiae. Apoptosis-like elimination of defective cells in S. cerevisiae and protozoa suggests that all unicellular life forms evolved altruistic programmed death that serves a variety of useful functions.

Lewis, Kim

2000-01-01

294

Control or Elimination of Undesirable Bacteria Using Parasitic Bdellovibrio Bacteria.  

National Technical Information Service (NTIS)

The invention relates to utilization of viable bacteria of the genus Bdellovibrio to control or eliminate undesirable bacteria in/on: one or more food contact surface(s) other than a surface of a food (i.e. surface(s) which are contacted with food, e.g. s...

R. C. Whiting

1991-01-01

295

Phosphonate utilization by bacteria.  

PubMed

Bacteria able to use at least one of 13 ionic alkylphosphonates of O-alkyl or O,O-dialkyl alkylphosphonates as phosphorus sources were isolated from sewage and soil. Four of these isolates used 2-aminoethylphosphonic acid (AEP) as a sole carbon, nitrogen, and phosphorus source. None of the other phosphonates served as a carbon source for the organisms. One isolate, identified as Pseudomonas putida, grew with AEP as its sole carbon, nitrogen, and phosphorus source and released nearly all of the organic phosphorus as orthophosphate and 72% of the AEP nitrogen as ammonium. This is the first demonstration of utilization of a phosphonoalkyl moiety as a sole carbon source. Cell-free extracts of P. putida contained an inducible enzyme system that required pyruvate and pyridoxal phosphate to release orthophosphate from AEP; acetaldehyde was tentatively identified as a second product. Phosphite inhibited the enzyme system. PMID:618850

Cook, A M; Daughton, C G; Alexander, M

1978-01-01

296

RNA localization in bacteria.  

PubMed

Bacteria localize proteins and DNA regions to specific subcellular sites, and several recent publications show that RNAs are localized within the cell as well. Localization of tmRNA and some mRNAs indicates that RNAs can be sequestered at specific sites by RNA binding proteins, or can be trapped at the location where they are transcribed. Although the functions of RNA localization are not yet completely understood, it appears that one function of RNA localization is to regulate RNA abundance by controlling access to nucleases. New techniques for visualizing RNAs will likely lead to increased examination of spatial control of RNAs and the role this control plays in the regulation of gene expression and bacterial physiology. PMID:21354362

Keiler, Kenneth C

2011-04-01

297

Antimicrobial activity of HR810 against 419 strict anaerobic bacteria.  

PubMed Central

HR810 and four other new beta-lactams were tested against 419 recent clinical anaerobic bacterial isolates. HR810 was found to have an antimicrobial spectrum most similar to that of cefotaxime, inhibiting 52.6% of Bacteroides fragilis group strains and 97.2% of all other anaerobic strains at an MIC of less than or equal to 16 micrograms/ml. Cefoxitin was found to have a narrower antimicrobial spectrum against the gram-positive anaerobic bacteria (8.4 to 10.1% less) than HR810 and cefotaxime, respectively.

Jones, R N; Gerlach, E H

1985-01-01

298

Mutation modifying the serine pathway in methylotrophic bacteria.  

PubMed

Methylotrophic bacteria, Gram-positive, with the serine pathway, were shown to have their growth inhibited by 0.5% glycine. The effects of this amino acid on individual enzyme activities were studied in wild and mutant strains of Micrococcus varians and Bacillus licheniformis. The enzymes studied were glycerate dehydrogenase (EC 1.1.1.29), isocitrate lyase (EC 4.1.3.1), serine hydroxymethyltransferase (EC 2.1.2.1) and glycine--oxaloacetate aminotransferase (EC 2.6.1.35). The last-named enzyme was found to be inhibited, the kinetic constants having been determined for two strain types. PMID:6792008

Ratomahenina, R; Galzy, P

1981-01-01

299

Bacteria tracking by in vivo magnetic resonance imaging  

PubMed Central

Background Different non-invasive real-time imaging techniques have been developed over the last decades to study bacterial pathogenic mechanisms in mouse models by following infections over a time course. In vivo investigations of bacterial infections previously relied mostly on bioluminescence imaging (BLI), which is able to localize metabolically active bacteria, but provides no data on the status of the involved organs in the infected host organism. In this study we established an in vivo imaging platform by magnetic resonance imaging (MRI) for tracking bacteria in mouse models of infection to study infection biology of clinically relevant bacteria. Results We have developed a method to label Gram-positive and Gram-negative bacteria with iron oxide nano particles and detected and pursued these with MRI. The key step for successful labeling was to manipulate the bacterial surface charge by producing electro-competent cells enabling charge interactions between the iron particles and the cell wall. Different particle sizes and coatings were tested for their ability to attach to the cell wall and possible labeling mechanisms were elaborated by comparing Gram-positive and -negative bacterial characteristics. With 5-nm citrate-coated particles an iron load of 0.015 ± 0.002 pg Fe/bacterial cell was achieved for Staphylococcus aureus. In both a subcutaneous and a systemic infection model induced by iron-labeled S. aureus bacteria, high resolution MR images allowed for bacterial tracking and provided information on the morphology of organs and the inflammatory response. Conclusion Labeled with iron oxide particles, in vivo detection of small S. aureus colonies in infection models is feasible by MRI and provides a versatile tool to follow bacterial infections in vivo. The established cell labeling strategy can easily be transferred to other bacterial species and thus provides a conceptual advance in the field of molecular MRI.

2013-01-01

300

Antimicrobial activity of the carnivorous plant Dionaea muscipula against food-related pathogenic and putrefactive bacteria.  

PubMed

Solvent extracts from the carnivorous plant Dionaea muscipula (Venus flytrap) were prepared using eight different organic solvents, and examined for antibacterial activity against food-related pathogenic and putrefactive bacteria. All solvent extracts showed higher antibacterial activity against gram positive bacteria than against gram negative bacteria. The TLC-bioautography analysis of the extracts revealed that a yellow spot was detected at Rf value of 0.85, which showed strong antibacterial activity. The UV, MS, and NMR analyses revealed that the antibacterial compound was plumbagin. PMID:24077538

Ogihara, Hirokazu; Endou, Fumiko; Furukawa, Soichi; Matsufuji, Hiroshi; Suzuki, Kouichi; Anzai, Hiroshi

2013-01-01

301

Extracellular vesicles produced by the Gram-positive bacterium Bacillus subtilis are disrupted by the lipopeptide surfactin.  

PubMed

Previously, extracellular vesicle production in Gram-positive bacteria was dismissed due to the absence of an outer membrane, where Gram-negative vesicles originate, and the difficulty in envisioning how such a process could occur through the cell wall. However, recent work has shown that Gram-positive bacteria produce extracellular vesicles and that the vesicles are biologically active. In this study, we show that Bacillus subtilis produces extracellular vesicles similar in size and morphology to other bacteria, characterized vesicles using a variety of techniques, provide evidence that these vesicles are actively produced by cells, show differences in vesicle production between strains, and identified a mechanism for such differences based on vesicle disruption. We found that in wild strains of B. subtilis, surfactin disrupted vesicles while in laboratory strains harbouring a mutation in the gene sfp, vesicles accumulated in the culture supernatant. Surfactin not only lysed B. subtilis vesicles, but also vesicles from Bacillus anthracis, indicating a mechanism that crossed species boundaries. To our knowledge, this is the first time a gene and a mechanism has been identified in the active disruption of extracellular vesicles and subsequent release of vesicular cargo in Gram-positive bacteria. We also identify a new mechanism of action for surfactin. PMID:24826903

Brown, Lisa; Kessler, Anne; Cabezas-Sanchez, Pablo; Luque-Garcia, Jose L; Casadevall, Arturo

2014-07-01

302

Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components  

NASA Technical Reports Server (NTRS)

Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

Gehron, M. J.; Davis, J. D.; Smith, G. A.; White, D. C.

1984-01-01

303

Magnetic microsphere-based methods to study the interaction of teicoplanin with peptides and bacteria  

Microsoft Academic Search

Teicoplanin (teic) from Actinoplanes teichomyceticus is a glycopeptide antibiotic used to treat many Gram-positive bacterial infections. Glycopeptide antibiotics inhibit bacterial\\u000a growth by binding to carboxy-terminal d-Ala-d-Ala intermediates in the peptidoglycan of the cell wall of Gram-positive bacteria. In this paper we report the derivatization\\u000a of magnetic microspheres with teic (teic-microspheres). Fluorescence-based techniques have been developed to analyze the binding\\u000a properties

Menake E. Piyasena; Lilian J. Real; Rochelle A. Diamond; H. Howard Xu; Frank A. Gomez

2008-01-01

304

The Genus Corynebacterium and Other Medically Relevant Coryneform-Like Bacteria  

PubMed Central

Catalase-positive Gram-positive bacilli, commonly called “diphtheroids” or “coryneform” bacteria were historically nearly always dismissed as contaminants when recovered from patients, but increasingly have been implicated as the cause of significant infections. These taxa have been underreported, and the taxa were taxonomically confusing. The mechanisms of pathogenesis, especially for newly described taxa, were rarely studied. Antibiotic susceptibility data were relatively scant. In this minireview, clinical relevance, phenotypic and genetic identification methods, matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) evaluations, and antimicrobial susceptibility testing involving species in the genus Corynebacterium and other medically relevant Gram-positive rods, collectively called coryneforms, are described.

2012-01-01

305

Heteropolysaccharides from lactic acid bacteria  

Microsoft Academic Search

Microbial exopolysaccharides are biothickeners that can be added to a wide variety of food products, where they serve as viscosifying, stabilizing, emulsifying or gelling agents. Numerous exopolysaccharides with different composition, size and structure are synthesized by lactic acid bacteria. The heteropolysaccharides from both mesophilic and thermophilic lactic acid bacteria have received renewed interest recently. Structural analysis combined with rheological studies

Luc De Vuyst; Bart Degeest

1999-01-01

306

Amidase activity of some bacteria.  

PubMed

The amidase activity of bacteria possessing a high nitrilase activity was found to display the same spectrum although the bacteria may belong to different taxonomic groups, Bacillus, Bacteridium, Micrococcus, Brevibacteriun. The spectrum of amidase activity, although very broad, is more restricted than that of nitrilase activity. Internal amides as well as vinyl-bound amides are not hydrolyzed. PMID:947836

Arnaud, A; Galzy, P; Jallageas, J C

1976-01-01

307

Quorum Sensing Let Bacteria Talk  

Microsoft Academic Search

Quorum Sensing (QS), a wonderful natural method to regulate gene expressions in response to the fluctuation in the cell density of a given bacterial population and provides the key mechanism through which bacteria communicate. QS bacteria release chemical signal molecules called autoinducers that increase in concentration as a function of cell density. Lots of bacterial physiological activities including symbiosis, virulence,

Indrani Bhattacharyya; Mayukh Choudhury

2008-01-01

308

Attachment of oral bacteria to a basement-membrane-like matrix and to purified matrix proteins.  

PubMed Central

The purpose of this study was to investigate the adherence of oral bacteria to an in vitro basement-membrane-like matrix and to selected individual macromolecular constituents of this matrix. Radiolabeled bacteria were incubated with basement-membrane-like matrices isolated from PF HR-9 cells. Bacteroides gingivalis 33277, Fusobacterium nucleatum FN-2, and Actinobacillus actinomycetemcomitans GA3(A) bound to the matrix in the range of 44 to 70%, considerably higher than the ranges of A. actinomycetemcomitans GA3(NA) and SUNY AB67 (range, 20 to 25%). The attachment of selected strains of gram-positive bacteria such as Streptococcus and Actinomyces spp. was much less frequent (range, 6 to 25%). Competitive inhibition studies demonstrated that preincubating the bacteria with fibronectin significantly decreased the binding of B. gingivalis by 51% but increased the binding of other gram-negative and gram-positive organisms tested. Similarly, preincubating the matrices with antifibronectin antibodies decreased the binding of B. gingivalis by 31%, whereas the other bacteria tested were either unaffected or binding was increased. The adherence of bacteria to purified basement membrane proteins was also investigated. Strain and species differences were seen in binding, but no clear relationship emerged between binding to an intact matrix and binding to isolated matrix proteins. The results of this study suggest that some gram-negative oral bacteria commonly associated with periodontal disease, such as B. gingivalis, A. actinomycetemcomitans, and F. nucleatum, bound in high numbers to basement-membrane-like matrices in vitro. On the other hand, the gram-positive strains tested bound in much fewer numbers. The results suggest that further studies with this in vitro model may aid in understanding the mechanisms by which oral bacteria adhere to basement membranes.

Winkler, J R; John, S R; Kramer, R H; Hoover, C I; Murray, P A

1987-01-01

309

Accumulation in gram-postive and gram-negative bacteria as a mechanism of resistance to erythromycin.  

PubMed

Erythromycin was recovered in high yield after incubation with gram-negative bacteria. The cell-free protein-synthesizing preparation from gram-negative bacteria is equally as susceptible to the antibiotic as is that from gram-positive bacteria. Thus, neither destruction of erythromycin nor the absence of the step susceptible to the antibiotic plays an important role in the resistance mechanism of gram-negative bacteria. A 100-fold difference in accumulation of erythromycin between gram-positive and gram-negative bacteria was observed. This alone explains the resistance of gram-negative bacteria to erythromycin. Furthermore, data showed that the inhibition of growth is closely related to the accumulation of erythromycin. The concentration of intracellular erythromycin in gram-positive bacteria was found to be 44- to 90-fold greater than that of the extracellular medium. However, the antibiotic did not accumulate on the cell walls, nor was the accumulation energy-dependent. It is proposed that it takes place by the binding of erythromycin to the bacterial ribosomes, forming a very stable complex. The dissociation constants of erythromycin-Staphylococcus aureus complex and erythromycin-Bacillus subtilis complex were determined to be 1.1 x 10(-7) and 3.4 x 11(-7)m, respectively. PMID:4966821

Mao, J C; Putterman, M

1968-03-01

310

Phosphoenolpyruvate:carbohydrate phosphotransferase systems of bacteria.  

PubMed Central

Numerous gram-negative and gram-positive bacteria take up carbohydrates through the phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS). This system transports and phosphorylates carbohydrates at the expense of PEP and is the subject of this review. The PTS consists of two general proteins, enzyme I and HPr, and a number of carbohydrate-specific enzymes, the enzymes II. PTS proteins are phosphoproteins in which the phospho group is attached to either a histidine residue or, in a number of cases, a cysteine residue. After phosphorylation of enzyme I by PEP, the phospho group is transferred to HPr. The enzymes II are required for the transport of the carbohydrates across the membrane and the transfer of the phospho group from phospho-HPr to the carbohydrates. Biochemical, structural, and molecular genetic studies have shown that the various enzymes II have the same basic structure. Each enzyme II consists of domains for specific functions, e.g., binding of the carbohydrate or phosphorylation. Each enzyme II complex can consist of one to four different polypeptides. The enzymes II can be placed into at least four classes on the basis of sequence similarity. The genetics of the PTS is complex, and the expression of PTS proteins is intricately regulated because of the central roles of these proteins in nutrient acquisition. In addition to classical induction-repression mechanisms involving repressor and activator proteins, other types of regulation, such as antitermination, have been observed in some PTSs. Apart from their role in carbohydrate transport, PTS proteins are involved in chemotaxis toward PTS carbohydrates. Furthermore, the IIAGlc protein, part of the glucose-specific PTS, is a central regulatory protein which in its nonphosphorylated form can bind to and inhibit several non-PTS uptake systems and thus prevent entry of inducers. In its phosphorylated form, P-IIAGlc is involved in the activation of adenylate cyclase and thus in the regulation of gene expression. By sensing the presence of PTS carbohydrates in the medium and adjusting the phosphorylation state of IIAGlc, cells can adapt quickly to changing conditions in the environment. In gram-positive bacteria, it has been demonstrated that HPr can be phosphorylated by ATP on a serine residue and this modification may perform a regulatory function.

Postma, P W; Lengeler, J W; Jacobson, G R

1993-01-01

311

Chlorine resistance patterns of bacteria from two drinking water distribution systems.  

PubMed Central

The relative chlorine sensitivities of bacteria isolated from chlorinated and unchlorinated drinking water distribution systems were compared by two independent methods. One method measured the toxic effect of free chlorine on bacteria, whereas the other measured the effect of combined chlorine. Bacteria from the chlorinated system were more resistant to both the combined and free forms of chlorine than those from the unchlorinated system, suggesting that there may be selection for more chlorine-tolerant microorganisms in chlorinated waters. Bacteria retained on the surfaces of 2.0-microns Nuclepore membrane filters were significantly more resistant to free chlorine compared to the total microbial population recovered on 0.2-micron membrane filters, presumably because aggregated cells or bacteria attached to suspended particulate matter exhibit more resistance than unassociated microorganisms. In accordance with this hypothesis, scanning electron microscopy of suspended particulate matter from the water samples revealed the presence of attached bacteria. The most resistant microorganisms were able to survive a 2-min exposure to 10 mg of free chlorine per liter. These included gram-positive spore-forming bacilli, actinomycetes, and some micrococci. The most sensitive bacteria were readily killed by chlorine concentrations of 1.0 mg liter-1 or less, and included most gram-positive micrococci, Corynebacterium/Arthrobacter, Klebsiella, Pseudomonas/Alcaligenes, Flavobacterium/Moraxella, and Acinetobacter. Images

Ridgway, H F; Olson, B H

1982-01-01

312

Selective depletion of bacteria alters but does not eliminate odors of individuality in Rattus norvegicus.  

PubMed

To determine if odors of individuality are influenced by the removal of Gram-negative or Gram-positive gut bacteria, Long-Evans rats were trained in an operant olfactometer to discriminate between the odors of two individual conspecifics and their operant responses to three different odors in randomly presented probe trials were analyzed. Significantly more responses were made to the probe odors from two known individuals than to the probe odors from known individuals with their Gram-negative bacteria eliminated (Experiment 1) or their Gram-positive bacteria eliminated (Experiment 2). Responses to the probe odors from known rats with bacterial selectively depleted did not differ significantly from responses to probe odors from unknown rats. These results support the hypothesis that the urinary odor of an individual rat is altered by the removal of specific gut bacteria. In Experiments 3 and 4, subjects made fewer errors in learning to discriminate between the odors of the familiar rats whose bacteria had been selectively depleted than between the odors of unknown rats. This "savings effect" indicates that some components of the individual urinary odors were retained after the removal of specific gut bacteria. Thus, the eliminated bacteria were not totally responsible for the odors of individuality. The outcome of Experiments 3 and 4 also indicates that conclusions regarding the recognition of odors by rats should not be made on the outcome of probe trial experiments alone. PMID:11006424

Schellinck, H M; Brown, R E

2000-01-01

313

The Cell Wall of Marine Autotrophic Bacteria.  

National Technical Information Service (NTIS)

A study has been made of the ultrastructure and composition of the cell envelope of different autotrophic bacteria. While emphasis was placed on the marine nitrifying bacteria, numerous strains of photosynthetic and methane-oxidizing bacteria were also ex...

C. C. Remsen

1971-01-01

314

Primers for overlooked nirK, qnorB, and nosZ genes of thermophilic Gram-positive denitrifiers.  

PubMed

Although efforts have been made the past few years, knowledge on genomic and phenotypic diversity and occurrence of the denitrification ability in Gram-positive bacteria are still fragmentary. Many environmental monitoring approaches have used nir, nor, and nos genes as marker genes for detection of denitrification or denitrifying bacteria. However, primers used in these methods often fail to detect the genes in specific bacterial taxa, such as Gram-positive denitrifiers. In this study, novel primer sets specifically targeting nirK, qnorB, and nosZ genes of the Firmicute genus Geobacillus were developed by genomic mining and tested in parallel with commonly used primers on a set of phylogenetically closely related denitrifying geobacilli. Novel nirK and qnorB sequences were recovered from all strains tested, whereas nosZ was detected in part of the strain set, which was in agreement with observed phenotypes. Interspecies and modest intraspecies variations in amplified fragment length polymorphism (AFLP) patterns were observed, verifying presence of genomic variation within the strain set. Our study shows that closely related Gram-positive denitrifiers may differ in denitrification phenotype and genotype. But foremost, novel primers targeting very divergent nirK, qnorB, and nosZ gene sequences of Gram-positive denitrifiers, are now available for cultivation-independent environmental surveys. PMID:24784780

Verbaendert, Ines; Hoefman, Sven; Boeckx, Pascal; Boon, Nico; De Vos, Paul

2014-07-01

315

Regulatory RNAs in Bacteria  

PubMed Central

RNA regulators in bacteria are a heterogenous group of molecules that act by various mechanisms to modulate a wide range of physiological responses. One class comprises riboswitches, which are parts of the mRNAs they regulate. These leader sequences fold into structures amenable to conformational changes upon the binding of small molecules. Riboswitches thus sense and respond to the availability of various nutrients in the cell. Other small transcripts bind to proteins, among them global regulators, and antagonize their functions. The largest and most extensively studied set of small RNA regulators act through base pairing with RNAs, usually modulating the translation and stability of mRNAs. The majority of these small RNAs regulate responses to changes in environmental conditions. Finally, a recently discovered group of RNA regulators, known as the CRISPR RNAs, contain short regions of homology to bacteriophage and plasmid sequences. CRISPR RNAs interfere with bacteriophage infection and plasmid conjugation by targeting the homologous foreign DNA through an unknown mechanism. Here we discuss what is known about these RNA regulators, as well as the many intriguing questions that remain to be addressed.

Waters, Lauren S.; Storz, Gisela

2011-01-01

316

Interactions between Diatoms and Bacteria  

PubMed Central

Summary: Diatoms and bacteria have cooccurred in common habitats for hundreds of millions of years, thus fostering specific associations and interactions with global biogeochemical consequences. Diatoms are responsible for one-fifth of the photosynthesis on Earth, while bacteria remineralize a large portion of this fixed carbon in the oceans. Through their coexistence, diatoms and bacteria cycle nutrients between oxidized and reduced states, impacting bioavailability and ultimately feeding higher trophic levels. Here we present an overview of how diatoms and bacteria interact and the implications of these interactions. We emphasize that heterotrophic bacteria in the oceans that are consistently associated with diatoms are confined to two phyla. These consistent bacterial associations result from encounter mechanisms that occur within a microscale environment surrounding a diatom cell. We review signaling mechanisms that occur in this microenvironment to pave the way for specific interactions. Finally, we discuss known interactions between diatoms and bacteria and exciting new directions and research opportunities in this field. Throughout the review, we emphasize new technological advances that will help in the discovery of new interactions. Deciphering the languages of diatoms and bacteria and how they interact will inform our understanding of the role these organisms have in shaping the ocean and how these interactions may change in future oceans.

Amin, Shady A.; Parker, Micaela S.

2012-01-01

317

Development of Mucosal Vaccines Based on Lactic Acid Bacteria  

NASA Astrophysics Data System (ADS)

Today, sufficient data are available to support the use of lactic acid bacteria (LAB), notably lactococci and lactobacilli, as delivery vehicles for the development of new mucosal vaccines. These non-pathogenic Gram-positive bacteria have been safely consumed by humans for centuries in fermented foods. They thus constitute an attractive alternative to the attenuated pathogens (most popular live vectors actually studied) which could recover their pathogenic potential and are thus not totally safe for use in humans. This chapter reviews the current research and advances in the use of LAB as live delivery vectors of proteins of interest for the development of new safe mucosal vaccines. The use of LAB as DNA vaccine vehicles to deliver DNA directly to antigen-presenting cells of the immune system is also discussed.

Bermúdez-Humarán, Luis G.; Innocentin, Silvia; Lefèvre, Francois; Chatel, Jean-Marc; Langella, Philippe

318

Role of commensal gut bacteria in inflammatory bowel diseases  

PubMed Central

Aberrant immune responses toward commensal gut bacteria can result in the onset and perpetuation of inflammatory bowel diseases (IBD). Reduced microbiota diversity in conjunction with lower proportion of Gram positive and higher proportion of Gram negative bacteria than in healthy subjects is frequently reported in IBD patients. In a subset of IBD patients, E. coli strains with specific features trigger disease. Important molecular mechanisms underlying this effect have been identified. However, in the majority of patients the exact nature of host-microbe interactions that contribute to IBD development has so far not been defined. The application of metagenomic techniques may help to identify bacterial functions that are involved in the aggravation or alleviation of IBD. Subsequently, the relevance for disease development of bacterial candidate genes may be tested taking advantage of reductionist animal models of chronic gut inflammation. This approach may help to identify bacterial functions that can be targeted in future concepts of IBD therapy.

Loh, Gunnar; Blaut, Michael

2012-01-01

319

Inactivation ofBiofilm Bacteria  

Microsoft Academic Search

Thecurrent project was developed toexamine inactivation ofbiofilm bacteria andtocharacterize the interaction ofbiocides withpipesurfaces. Unattached bacteria were quite susceptible tothevariety of disinfectants tested. Viable bacterial counts were reduced 99%byexposureto0.08 mg ofhypochlorous acid (pH7.0) perliter (1to2°C) for1min.Formonochloramine, 94mg\\/liter wasrequired tokill 99%ofthebacteria within 1min.Theseresults wereconsistent withthose found byother investigators. Biofilm bacteria grown on thesurfaces ofgranular activated carbon particles, metal coupons,orglass microscope slides were

MARK W. LECHEVALLIER; CHERYL D. CAWTHON; RAMON G. LEE

1988-01-01

320

Sampling bacteria with a laser  

NASA Astrophysics Data System (ADS)

Water quality is a topic of high interest and it's getting more and more important due to climate change and the implementation of European Water Framework Directive (WFD). One point of interest here is the inflow of bacteria into a river caused by combined sewer overflows which lead untreated wastewater including bacteria directly into a river. These bacteria remain in the river for a certain time, they settle down and can be remobilised again. In our study we want to investigate these processes of sedimentation and resuspension and use the results for the development of a software module coupled with the software Flow3D. Thereby we should be able to simulate and therefore predict the water quality influenced by combined sewer overflows. Hence we need to get information about the bacteria transport and fate. We need to know about the size of the bacteria or of the bacteria clumps and the size of the particles the bacteria are attached to. The agglomerates lead to different characteristics and velocities of settlement. The timespan during this bacteria can be detected in the bulk phase depends on many factors like the intensity of UV light, turbidity of the water, the temperature of the water, if there are grazers and a lot more. The size, density and composition of the agglomerates is just a part of all these influencing factors, but it is extremely difficult to differ between the other effects if we have no information about the simple sedimentation in default of these basic information. However we have a big problem getting the data. The chaining between bacteria or bacteria and particles is not too strong, so filtering the water to get a sieving curve may destroy these connections. We did some experiments similar to PIV (particle image velocimetry) measurements and evaluated the pictures with a macro written for the software ImageJ. Doing so we were able to get the concentration of bacteria in the water and collect information about the size of the bacteria. We also compared these data to samples of usual collection and filtering. The results of these laser measurements are very promising.

Schwarzwälder, Kordula; Rutschmann, Peter

2014-05-01

321

Mechanical Consequences of Cell-Wall Turnover in the Elongation of a Gram-Positive Bacterium  

PubMed Central

A common feature of walled organisms is their exposure to osmotic forces that challenge the mechanical integrity of cells while driving elongation. Most bacteria rely on their cell wall to bear osmotic stress and determine cell shape. Wall thickness can vary greatly among species, with Gram-positive bacteria having a thicker wall than Gram-negative bacteria. How wall dimensions and mechanical properties are regulated and how they affect growth have not yet been elucidated. To investigate the regulation of wall thickness in the rod-shaped Gram-positive bacterium Bacillus subtilis, we analyzed exponentially growing cells in different media. Using transmission electron and epifluorescence microscopy, we found that wall thickness and strain were maintained even between media that yielded a threefold change in growth rate. To probe mechanisms of elongation, we developed a biophysical model of the Gram-positive wall that balances the mechanical effects of synthesis of new material and removal of old material through hydrolysis. Our results suggest that cells can vary their growth rate without changing wall thickness or strain by maintaining a constant ratio of synthesis and hydrolysis rates. Our model also indicates that steady growth requires wall turnover on the same timescale as elongation, which can be driven primarily by hydrolysis rather than insertion. This perspective of turnover-driven elongation provides mechanistic insight into previous experiments involving mutants whose growth rate was accelerated by the addition of lysozyme or autolysin. Our approach provides a general framework for deconstructing shape maintenance in cells with thick walls by integrating wall mechanics with the kinetics and regulation of synthesis and turnover.

Misra, Gaurav; Rojas, Enrique R.; Gopinathan, Ajay; Huang, Kerwyn Casey

2013-01-01

322

Effects of Ultraviolet Radiation on the Gram-positive marine bacterium Microbacterium maritypicum.  

PubMed

Although extensive information is available on the effect ultraviolet (UV) radiation has on Gram-negative marine bacteria, there is a scarcity of data concerning UV radiation and Gram-positive marine bacteria. The focus of this paper is on Microbacterium maritypicum, with the Gram-negative Vibrio natriegens being used as a standard of comparison. M. maritypicum exhibited growth over a NaCl range of 0-1000 mM: , with optimum growth occurring between 0 and 400 mM: NaCl. In contrast, V. natriegens grew over a NaCl span of 250-1000 mM: , with best growth being observed between 250 and 600 mM: NaCl. UV radiation experiments were done using the medium with 250 mM: NaCl. For solar (UV-A and B) radiation and log-phase cells, M. maritypicum was determined to be three times more resistant than V. natriegens. For germicidal (UV-C) radiation, the pattern of resistance of the log-phase cells to the lethal effects of the radiation was even more pronounced, with the Gram-positive bacterium being more than 12 to 13 times more resistant. Similar data to the solar and germicidal log-phase UV kill curves were obtained for stationary-phase cells of both organisms. Photoreactivation was observed for both types of cells exposed to UV-C but none for cells treated with UV-A and B. When log phase cells of M.maritypicum were grown at 0.0 and 0.6 M: NaCl and exposed to UV-C radiation, no difference in survivorship patterns was noted from that of 0.25 M: NaCl grown cells. Although this study has only focused on two marine bacteria, our results indicate that the Gram-positive M. maritypicum could have a built-in advantage for survival in some marine ecosystems. PMID:17551790

Williams, Patrick D; Eichstadt, Shaundra L; Kokjohn, Tyler A; Martin, Eugene L

2007-07-01

323

Cytokinesis in Bacteria  

PubMed Central

Work on two diverse rod-shaped bacteria, Escherichia coli and Bacillus subtilis, has defined a set of about 10 conserved proteins that are important for cell division in a wide range of eubacteria. These proteins are directed to the division site by the combination of two negative regulatory systems. Nucleoid occlusion is a poorly understood mechanism whereby the nucleoid prevents division in the cylindrical part of the cell, until chromosome segregation has occurred near midcell. The Min proteins prevent division in the nucleoid-free spaces near the cell poles in a manner that is beginning to be understood in cytological and biochemical terms. The hierarchy whereby the essential division proteins assemble at the midcell division site has been worked out for both E. coli and B. subtilis. They can be divided into essentially three classes depending on their position in the hierarchy and, to a certain extent, their subcellular localization. FtsZ is a cytosolic tubulin-like protein that polymerizes into an oligomeric structure that forms the initial ring at midcell. FtsA is another cytosolic protein that is related to actin, but its precise function is unclear. The cytoplasmic proteins are linked to the membrane by putative membrane anchor proteins, such as ZipA of E. coli and possibly EzrA of B. subtilis, which have a single membrane span but a cytoplasmic C-terminal domain. The remaining proteins are either integral membrane proteins or transmembrane proteins with their major domains outside the cell. The functions of most of these proteins are unclear with the exception of at least one penicillin-binding protein, which catalyzes a key step in cell wall synthesis in the division septum.

Errington, Jeffery; Daniel, Richard A.; Scheffers, Dirk-Jan

2003-01-01

324

Evaluation of Cariogenic Bacteria  

PubMed Central

Objectives The evaluation of Mutans streptococci (MS) is one of the index for caries risk. DentocultTM and CRTTM are commercial kits to detect and evaluate MS, conveniently. However, the evaluation of MS has also been carried out simply using an instruction manual. But the instruction manual is not easy to use for evaluation of MS. The aim of this study was to examine the utility of modified Mitis-Salivalius Bacitracin (MSB) agar medium compared with MSB agar medium and commercial kits, and to establish a convenient kit (mMSB-kit) using modified MSB agar. Methods The MS in stimulated saliva from 27 subjects were detected by MSB, modified MSB agar medium and commercial kits. Laboratory and clinically isolated strains of MS were similarly evaluated. The ratios of MS in detected bacteria were compared by ELISA. Results The scores using an mMSB-kit on the basis of modified MSB agar medium were tabulated. Saliva samples showed different levels of MS between culture methods and the commercial kit. Some samples which were full of MS were not detected by the commercial kit. The detection of MS by modified MSB agar medium and mMSB-kit were significantly higher when compared with MSB agar medium,CRTTM, (P< .01) and Dentocult SMTM (P<.05). Conclusion The sensitivity for detection of MS is higher for modified MSB agar medium when compared with MSB agar medium. The mMSB-kit can be used simply, and can be an important contributor for the evaluation of MS as a caries risk factor.

Nishikawara, Fusao; Nomura, Yoshiaki; Imai, Susumu; Senda, Akira; Hanada, Nobuhiro

2007-01-01

325

In Vitro Activities of Linezolid against Important Gram-Positive Bacterial Pathogens Including Vancomycin-Resistant Enterococci  

Microsoft Academic Search

The emergence of resistance in gram-positive bacteria has necessitated a search for new antimicrobial agents. Linezolid is an oxazolidinone, a new class of antibacterial agents with enhanced activity against pathogens. We compared the activity of linezolid to those of other antimicrobial agents against 3,945 clinical isolates. Linezolid demonstrated potent activity against all isolates tested. For all vancomycin-susceptible enterococci, staphylococci, and

GARY A. NOSKIN; FARIDA SIDDIQUI; VALENTINA STOSOR; DONNA HACEK; LANCE R. PETERSON

1999-01-01

326

Potential for luxS related signalling in marine bacteria and production of autoinducer-2 in the genus Shewanella  

Microsoft Academic Search

BACKGROUND: The autoinducer-2 (AI-2) group of signalling molecules are produced by both Gram positive and Gram negative bacteria as the by-product of a metabolic transformation carried out by the LuxS enzyme. They are the only non species-specific quorum sensing compounds presently known in bacteria. The luxS gene coding for the AI-2 synthase enzyme was found in many important pathogens. Here,

Agnes Bodor; Bettina Elxnat; Verena Thiel; Stefan Schulz; Irene Wagner-Döbler

2008-01-01

327

Isolation and Characterization of Polycyclic Aromatic Hydrocarbon-Degrading Bacteria Associated with the Rhizosphere of Salt Marsh Plants  

Microsoft Academic Search

Polycyclic aromatic hydrocarbon (PAH)-degrading bacteria were isolated from contaminated estuarine sediment and salt marsh rhizosphere by enrichment using either naphthalene, phenanthrene, or biphenyl as the sole source of carbon and energy. Pasteurization of samples prior to enrichment resulted in isolation of gram-positive, spore-forming bacteria. The isolates were characterized using a variety of phenotypic, morpho- logic, and molecular properties. Identification of

L. L. Daane; I. Harjono; G. J. Zylstra; M. M. Haggblom

2001-01-01

328

Effects of Rhamnolipids from Pseudomonas aeruginosa DS10-129 on Luminescent Bacteria: Toxicity and Modulation of Cadmium Bioavailability  

Microsoft Academic Search

In this study, the mixture of mono- and di-rhamnolipids produced by Pseudomonas aeruginosa DS10-129 was characterized for its toxicity and modulatory effects on Cd availability to different bacteria. Gram-negative\\u000a naturally bioluminescent Vibrio fischeri and recombinant bioluminescent Pseudomonas fluorescens, P. aeruginosa, Escherichia coli, and Gram-positive Bacillus subtilis were used as model organisms. Rhamnolipids reduced the bioluminescence of these bacteria in less

Olesja Bondarenko; Pattanathu K. S. M. Rahman; Thahira J. Rahman; Anne Kahru; Angela Ivask

2010-01-01

329

Removal and recovery of heavy metals by bacteria isolated from activated sludge treating industrial effluents and municipal wastewater  

Microsoft Academic Search

A total of nineteen metal-resistant and non-resistant bacteria from activated sludge treating both metal-contaminated industrial effluents and municipal wastewater were isolated and identified. These included both Gram-positive (e.g. Micrococcus) and Gram-negative (e.g. Pseudomonas) bacteria. The biosorption capacity of these strains for five different heavy metals (copper, nickel, zinc, lead and chromium) was determined at pH 5 and initial metal concentration

W. C. Leung; M. F. Wong; H. Chua; W. Lo; P. H. F. Yu; C. K. Leung

330

Bacteriocin-Like Activity of Butyrivibrio fibrisolvens JL5 and Its Effect on Other Ruminal Bacteria and Ammonia Production  

Microsoft Academic Search

greater than 106. The 108 and 109 dilutions contained bacteria that fermented carbohydrates, and some of these bacteria inhibited Clostridium sticklandii SR, an obligate amino acid-fermenting bacterium. Phylogenetic analysis indicated that the most active isolate (JL5) was closely related to Butyrivibrio fibrisolvens B835. Strain JL5 inhibited B. fibrisolvens 49 and a variety of other gram-positive organisms, but it had little

Jennifer L. Rychlik; James B. Russell

2002-01-01

331

Protein Surface Layers of Bacteria.  

National Technical Information Service (NTIS)

On the outer surface, many genera of bacteria assemble layers composed of repetitive, regularly aligned, proteinaceous subunits. These layers, essentially two-dimensional paracrystalline arrays, are usually the outer molecular layer of the organism and so...

J. Smit

1986-01-01

332

[Nitrilase activity in several bacteria].  

PubMed

Eighteen strains of Bacteria from the genus Bacillus, Bacteridium, Micrococcus and Brevibacterium were isolated. They have a very general nitrilase activity that acts on all the substrates with nitrile function. PMID:825308

Arnaud, A; Galzy, P; Jallageas, J C

1976-09-20

333

Environmental sources of fecal bacteria  

USGS Publications Warehouse

This chapter provides a review of the research on environmental occurrences of faecal indicator bacteria in a variety of terrestrial and aquatic habitats under different geographic and climatic conditions, and discusses how these external sources may affect surface water quality.

Byappanahalli, Muruleedhara N.; Ishii, Satoshi

2011-01-01

334

MICROBIOLOGY: How Bacteria Respire Minerals  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required: Some bacteria respire minerals; that is, they harvest energy from minerals through using them as electron acceptors. Many details of this respiration process have remained obscure. In her Perspective, Newman highlights the study by Lower et al., who have used a customized atomic force microscope to observe bacteria during mineral respiration.

Dianne K. Newman (California Institute of Technology;Division of Geological and Planetary Sciences)

2001-05-18

335

Anaerobic bacteria that dechlorinate perchloroethene.  

PubMed Central

In this study, we identified specific cultures of anaerobic bacteria that dechlorinate perchlorethene (PCE). The bacteria that significantly dechlorinated PCE were strain DCB-1, an obligate anaerobe previously shown to dechlorinate chlorobenzoate, and two strains of Methanosarcina. The rate of PCE dechlorination by DCB-1 compared favorably with reported rates of trichloroethene bio-oxidation by methanotrophs. Even higher PCE dechlorination rates were achieved when DCB-1 was grown in a methanogenic consortium.

Fathepure, B Z; Nengu, J P; Boyd, S A

1987-01-01

336

SPECTROCHEMICAL ANALYSIS OF INORGANIC ELEMENTS IN BACTERIA.  

PubMed

Rouf, M. A. (Washington State University, Pullman). Spectrochemical analysis of inorganic elements in bacteria. J. Bacteriol. 88:1545-1549. 1964.-Quantitative spectrochemical analyses of inorganic elements in the vegetative cells of Escherichia coli, Sphaerotilus natans, Micrococcus roseus, Bacillus cereus, and the spores of B. cereus were made. The following elements were found to be present in the ash samples: B, Na, Mg, Al, Si, P, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Sr, S, Ag, Sn, Ba, Pb, V, and Mo. These could be divided into major, minor, and trace elements, depending on the relative amounts in the cells. Mg, P, K, and S were considered as the major elements; Ca, Fe, Zn, and, perhaps, Cu and Mn as the minor elements, and the rest as trace elements. Mg concentrations were higher in the cells of the gram-positive M. roseus and B. cereus than in the gram-negative E. coli and S. natans. The latter organism contained 2.6% Fe(2)O(3) (dry weight basis). The vegetative cells of B. cereus were higher in Mg, P, K, Na, Ag, and lower in Si, Ca, Zn, Mn, and Cu than were its spores. PMID:14240935

ROUF, M A

1964-12-01

337

Recovery and Identification of Viable Bacteria Immured in Glacial Ice  

NASA Astrophysics Data System (ADS)

An extraction system has been constructed that melts ice from the interior of ice cores and collects the resulting water aseptically. Using this system, bacteria entrapped in ice cores from different geographic locations, that range in age from 5 to 20,000 years old, have been isolated and characterized. Ice cores from the Guliya ice cap on the Tibetan Plateau (China) contained the highest number of colony-forming units per milliliter (˜180 cfu ml -1) and representatives of many different bacterial species. Much lower numbers of bacteria (>20 cfu ml -1) were recovered from Sajama (Bolivia) ice cores, although in general such nonpolar ice cores contained more culturable bacteria than samples of polar ice, presumably due to the closer proximity of major biological ecosystems. More bacteria were recovered from Late Holocene ice from the Taylor Dome region than from ice of the same age from the Antarctic peninsula or from Greenland. Bacterial isolates were identified, in terms of their closest phylogenetic relatives, by determining small-subunit ribosomal RNA-encoding DNA sequences (16S rDNAs), and most were related to spore-forming Bacillus and Actinomycetes species, or to nonsporulating Gram positive bacteria. The numbers of recoverable bacteria did not correlate directly with the age of the ice, indicating that most bacteria were deposited episodically in snowflakes and/or attached to larger particles of inorganic and organic debris. By identifying the features that facilitate microbial survival within terrestrial ice, extrapolations to the likelihood of microorganisms surviving frozen in water ice on Mars, Europa, or within comets will be improved.

Christner, Brent C.; Mosley-Thompson, Ellen; Thompson, Lonnie G.; Zagorodnov, Victor; Sandman, Kathleen; Reeve, John N.

2000-04-01

338

MOTILE MARINE BACTERIA. I. TECHNIQUES, ECOLOGY, AND GENERAL CHARACTERISTICS.  

PubMed

Leifson, Einar (Loyola University, Chicago, Ill.), B. J. Cosenza, R. Murchelano, and R. C. Cleverdon. Motile marine bacteria. I. Techniques, ecology, and general characteristics. J. Bacteriol. 87:652-666. 1964.-Aerobic, heterotrophic bacteria were isolated from the waters of the Long Island Sound, Narragansett Bay, Atlantic Ocean, and from the intestine of a variety of marine animals found along the shore of the Long Island Sound. A total of about 600 cultures of motile bacteria were studied morphologically and physiologically, with special emphasis on flagellar characteristics. The great majority of the bacteria isolated from the water were polar flagellate, nonfermentative, nonpigmented, and gramnegative. Most of these were straight, capsulated rods, but a considerable number were curved like vibrios. Yellow-pigmented isolates were often nonmotile, and the motile forms were most frequently subpolar flagellate. Several rosette-forming bacteria, including Caulobacter species, were isolated. Two typical spirilla and one flagellated coccus were found. Peritrichous flagellate bacteria, both gram-positive and gram-negative, were rare except in bottom mud. The normal intestinal flora of marine animals, such as fish and shellfish, consisted of polar flagellate, fermentative, non-pigmented, gram-negative, straight rods. Curved forms, like vibrios, were less common. Polar multitrichous flagellate forms were not uncommon and included all the luminescent types isolated. A considerable proportion of the polar monotrichous flagellate rods swarmed over the surface of agar media. When grown on solid media, all of these showed mixed polar and lateral flagellation; in liquid media, mainly polar flagellation was found. The ecology and general taxonomy of marine bacteria are discussed. PMID:14129669

LEIFSON, E; COSENZA, B J; MURCHELANO, R; CLEVERDON, R C

1964-03-01

339

Antimicrobial action of propolis and some of its components: the effects on growth, membrane potential and motility of bacteria  

Microsoft Academic Search

The effect of the natural bee product propolis on the physiology of microorganisms was investigated using B. subtilis, E. coli and R. sphaeroides. An ethanolic extract of propolis had a bactericidal effect caused by the presence of very active, but labile, ingredients. The exact bactericidal effect of propolis was species dependent: it was effective against gram-positive and some gram-negative bacteria.

O. K. Mirzoeva; R. N. Grishanin; P. C. Calder

1997-01-01

340

Occurrence and ultrastructural characterization of bacteria in association with and isolated from Azolla caroliniana.  

PubMed Central

The occurrence and ultrastructure of bacteria in leaf cavities of symbiotic Azolla caroliniana were examined by transmission electron microscopy. Bacteria were observed in all leaf cavities of Azolla cultures. Five ultrastructurally distinct types of bacteria were observed in each individual leaf cavity. Features used to characterize the bacteria included morphology, cell wall structure, and cytoplasmic organization. At least one gram-positive and as many as four gram-negative types of bacteria reside in leaf cavities of A. caroliniana. The morphological and ultrastructural characteristics of the gram-positive bacterium suggest that it is an Arthrobacter sp. The gram-negative bacteria could not be cultured; therefore, they have not been classified further. Bacterial cell shape and cell wall structure were similar in leaf cavities of different ages, but cell size and cytoplasmic composition varied. The relative contributions of each bacterial type to the total community within individual leaves was determined. Ultrastructural characteristics of bacterial isolates cultured from A. caroliniana in a free-living state were also examined. Images

Nierzwicki-Bauer, S A; Aulfinger, H

1991-01-01

341

Graphene-based photothermal agent for rapid and effective killing of bacteria.  

PubMed

Conventional antibiotic therapies are becoming less efficient due to the emergence of antibiotic-resistant bacterial strains. Development of novel antibacterial material to effectively inhibit or kill bacteria is crucial. A graphene-based photothermal agent, magnetic reduced graphene oxide functionalized with glutaraldehyde (MRGOGA), was synthesized for efficient capture and effective killing of both gram-positive Staphylococcus aureus ( S. aureus ) and gram-negative Escherichia coli ( E. coli ) bacteria upon near-infrared (NIR) laser irradiation. In the present work, we took advantage of the excellent photothermal properties of reduced graphene oxide upon NIR laser irradiation and glutaraldehyde as an efficient capturing agent toward both bacteria. Its magnetic characteristic allows bacteria to be readily trapped in a small volume by the external magnet. The synergetic effects increase the heating extent by MRGOGA upon NIR laser irradiation and the killing of the captured bacteria. The survival rate and membrane integrity assay demonstrate that 80 ppm MRGOGA solution provided rapid and effective killing of up to 99% of both gram-positive and gram-negative bacteria in 10 min upon NIR laser irradiation under batch operation mode. Graphene demonstrated better photothermal antibacterial efficiency than carbon nanotubes. Furthermore, a microfluidic chip system under continuous operation mode demonstrates the reusability of MRGOGA and offers a biocompatible platform for online phothothermal sterilization. PMID:23363079

Wu, Meng-Chin; Deokar, Archana R; Liao, Jhan-Hong; Shih, Po-Yuan; Ling, Yong-Chien

2013-02-26

342

Isolation, characterization and phylogeny of sponge-associated bacteria with antimicrobial activities from Brazil.  

PubMed

Bacteria associated with marine sponges represent a rich source of bioactive metabolites. The aim of this study was to isolate and characterize bacteria with antimicrobial activities from Brazilian sponges. A total of 158 colony-forming units were isolated from nine sponge species. Among these, 12 isolates presented antimicrobial activities against pathogenic bacteria. Based on comparative sequence analysis of their 16S rRNA genes, the sponge-associated bacterial strains could be subdivided into three phylogenetically different clusters. Five strains were affiliated with Firmicutes (genera Bacillus and Virgibacillus), three with alpha-Proteobacteria (Pseudovibrio sp.) and four with gamma-Proteobacteria (genera Pseudomonas and Stenotrophomonas). The sponge-associated bacterial strains Pseudomonas fluorescens H40 and H41 and Pseudomonas aeruginosa H51 exhibited antimicrobial activity against both Gram-negative and Gram-positive bacteria, including strains such as vancomycin-resistant Enterococcus faecium and multiresistant Klebsiella pneumoniae. Bacillus pumilus Pc31 and Pc32, Pseudovibrio ascidiaceicola Pm31 and Ca31 and Pseudovibrio denitrificans Mm37 strains were more effective against Gram-positive bacteria. These findings suggest that the identified strains may contribute to the search for new sources of antimicrobial substances, an important strategy for developing alternative therapies to treat infections caused by multidrug-resistant bacteria. PMID:20600863

Santos, Olinda C S; Pontes, Paula V M L; Santos, Juliana F M; Muricy, Guilherme; Giambiagi-deMarval, Marcia; Laport, Marinella S

2010-09-01

343

The acetylproteome of Gram-positive model bacterium Bacillus subtilis.  

PubMed

N(?) -lysine acetylation, a reversible and highly regulated PTM, has been shown to occur in the model Gram-negative bacteria Escherichia coli and Salmonella enterica. Here, we extend this acetylproteome analysis to Bacillus subtilis, a model Gram-positive bacterium. Through anti-acetyllysine antibody-based immunoseparation of acetylpeptides followed by nano-HPLC/MS/MS analysis, we identified 332 unique lysine-acetylated sites on 185 proteins. These proteins are mainly involved in cellular housekeeping functions such as central metabolism and protein synthesis. Fifity-nine of the lysine-acetylated proteins showed homology with lysine-acetylated proteins previously identified in E. coli, suggesting that acetylated proteins are more conserved. Notably, acetylation was found at or near the active sites predicted by Prosite signature, including SdhA, RocA, Kbl, YwjH, and YfmT, indicating that lysine acetylation may affect their activities. In 2-amino-3-ketobutyrate CoA ligase Kbl, a class II aminotransferase, a lysine residue involved in pyridoxal phosphate attachment was found to be acetylated. This data set provides evidence for the generality of lysine acetylation in eubacteria and opens opportunities to explore the consequences of acetylation modification on the molecular physiology of B. subtilis. PMID:23468065

Kim, Dooil; Yu, Byung Jo; Kim, Jung Ae; Lee, Yong-Jik; Choi, Soo-Geun; Kang, Sunghyun; Pan, Jae-Gu

2013-05-01

344

Streptococcus mutans: a new Gram-positive paradigm?  

PubMed Central

Despite the enormous contributions of the bacterial paradigms Escherichia coli and Bacillus subtilis to basic and applied research, it is well known that no single organism can be a perfect representative of all other species. However, given that some bacteria are difficult, or virtually impossible, to cultivate in the laboratory, that some are recalcitrant to genetic and molecular manipulation, and that others can be extremely dangerous to manipulate, the use of model organisms will continue to play an important role in the development of basic research. In particular, model organisms are very useful for providing a better understanding of the biology of closely related species. Here, we discuss how the lifestyle, the availability of suitable in vitro and in vivo systems, and a thorough understanding of the genetics, biochemistry and physiology of the dental pathogen Streptococcus mutans have greatly advanced our understanding of important areas in the field of bacteriology such as interspecies biofilms, competence development and stress responses. In this article, we provide an argument that places S. mutans, an organism that evolved in close association with the human host, as a novel Gram-positive model organism.

Quivey, Robert G.; Koo, Hyun; Abranches, Jacqueline

2013-01-01

345

Glycopeptide resistance in gram-positive cocci: a review.  

PubMed

Vancomycin-resistant enterococci (VRE) have emerged as important nosocomial pathogens in the past two decades all over the world and have seriously limited the choices available to clinicians for treating infections caused by these agents. Methicillin-resistant Staphylococcus aureus, perhaps the most notorious among the nosocomial pathogens, was till recently susceptible to vancomycin and the other glycopeptides. Emergence of vancomycin nonsusceptible strains of S. aureus has led to a worrisome scenario where the options available for treating serious infections due to these organisms are very limited and not well evaluated. Vancomycin resistance in clinically significant isolates of coagulase-negative staphylococci is also on the rise in many setups. This paper aims to highlight the genetic basis of vancomycin resistance in Enterococcus species and S. aureus. It also focuses on important considerations in detection of vancomycin resistance in these gram-positive bacteria. The problem of glycopeptide resistance in clinical isolates of coagulase-negative staphylococci and the phenomenon of vancomycin tolerance seen in some strains of Streptococcus pneumoniae has also been discussed. Finally, therapeutic options available and being developed against these pathogens have also found a mention. PMID:22778729

Sujatha, S; Praharaj, Ira

2012-01-01

346

Carotenoids and Carotenogenesis in Anoxygenic Photosynthetic Bacteria  

Microsoft Academic Search

More than 50 genera including about 130 species of anoxygenic photosynthetic bacteria have been described. These bacteria produce around 100 different carotenoids. In this chapter, the carotenoid compositions of all the photosynthetic bacteria so far described are summarized. All of the carotenogenesis genes from Rhodobacter, and some of them from other bacteria have been cloned, and the characteristics of their

Shinichi Takaichi

347

Silver Enhances Antibiotic Activity Against Gram-negative Bacteria  

PubMed Central

A declining pipeline of clinically useful antibiotics has made it imperative to develop more effective antimicrobial therapies, particularly against difficult-to-treat Gram-negative pathogens. Silver has been used as an antimicrobial since antiquity, yet its mechanism of action remains unclear. Here, we show that silver disrupts multiple bacterial cellular processes, including disulfide bond formation, metabolism and iron homeostasis. These changes lead to increased production of reactive oxygen species (ROS) and increased membrane permeability of Gram-negative bacteria, that can potentiate the activity of a broad range of antibiotics against Gram-negative bacteria in different metabolic states, as well as restore antibiotic susceptibility to a resistant bacterial strain. We show both in vitro and in a mouse model of urinary tract infection that the ability of silver to induce oxidative stress can be harnessed to potentiate antibiotic activity. Additionally, we demonstrate in vitro and in two different mouse models of peritonitis that silver sensitizes Gram-negative bacteria to the Gram-positive specific antibiotic, vancomycin, thereby expanding the antibacterial spectrum of this drug. Finally, we used silver and antibiotic combinations in vitro to eradicate bacterial persister cells, and show both in vitro and in a mouse biofilm infection model, that silver can enhance antibacterial action against biofilms. This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria thus strengthening the antibiotic arsenal for fighting bacterial infections.

Spina, Catherine S.; Collins, James J.

2013-01-01

348

Characteristics of airborne bacteria in Mumbai urban environment.  

PubMed

Components of biological origin constitute small but a significant proportion of the ambient airborne particulate matter (PM). However, their diversity and role in proinflammatory responses of PM are not well understood. The present study characterizes airborne bacterial species diversity in Mumbai City and elucidates the role of bacterial endotoxin in PM induced proinflammatory response in ex vivo. Airborne bacteria and endotoxin samples were collected during April-May 2010 in Mumbai using six stage microbial impactor and biosampler. The culturable bacterial species concentration was measured and factors influencing the composition were identified by principal component analysis (PCA). The biosampler samples were used to stimulate immune cells in whole blood assay. A total of 28 species belonging to 17 genera were identified. Gram positive and spore forming groups of bacteria dominated the airborne culturable bacterial concentration. The study indicated the dominance of spore forming and human or animal flora derived pathogenic/opportunistic bacteria in the ambient air environment. Pathogenic and opportunistic species of bacteria were also present in the samples. TNF-? induction by PM was reduced (35%) by polymyxin B pretreatment and this result was corroborated with the results of blocking endotoxin receptor cluster differentiation (CD14). The study highlights the importance of airborne biological particles and suggests need of further studies on biological characterization of ambient PM. PMID:24815556

Gangamma, S

2014-08-01

349

Heterogeneity of Surfaces of Subgingival Bacteria as Detected by Zeta Potential Measurements  

Microsoft Academic Search

Porphyromonasgingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans (A.a.) are Gram-negative bacteria which are implicated in various forms of periodontal disease. The Gram-positive Peptostreptococcus micros may also play an important role. For investigation of the possible adhesion and colonization mechanisms of these organisms, the charge properties of the outermost layers of bacterial cell surfaces were studied through the measurement of zeta potentials

M. M. Cowan; H. C. Van der Mei; I. Stokroos; H. J. Busscher

1992-01-01

350

Production of class II bacteriocins by lactic acid bacteria; an example of biological warfare and communication  

Microsoft Academic Search

Lactic acid bacteria (LAB) fight competing Gram-positive microorganisms by secreting anti-microbial peptides called bacteriocins.\\u000a Peptide bacteriocins are usually divided into lantibiotics (class I) and non-lantibiotics (class II), the latter being the\\u000a main topic of this review. During the past decade many of these bacteriocins have been isolated and characterized, and elements\\u000a of the genetic mechanisms behind bacteriocin production have been

Vincent G. H. Eijsink; Lars Axelsson; Dzung B. Diep; Leiv S. Håvarstein; Helge Holo; Ingolf F. Nes

2002-01-01

351

Selective depletion of bacteria alters but does not eliminate odors of individuality in Rattus norvegicus  

Microsoft Academic Search

To determine if odors of individuality are influenced by the removal of Gram-negative or Gram-positive gut bacteria, Long–Evans rats were trained in an operant olfactometer to discriminate between the odors of two individual conspecifics and their operant responses to three different odors in randomly presented probe trials were analyzed. Significantly more responses were made to the probe odors from two

Heather MacIntosh Schellinck; Richard E Brown

2000-01-01

352

Experimental measurements of the reversibility of metal–bacteria adsorption reactions  

Microsoft Academic Search

This study tests the reversibility of metal–bacteria interactions by comparing estimated extents of desorption based on surface complexation modeling, to those we observed in the experimental adsorption\\/desorption systems. The experiments also determine if extended adsorption contact time affects desorption kinetics. The experiments involved Ca and Cd adsorption\\/desorption onto the surface of a gram positive bacterium: Bacillus subtilis. Three types of

David A. Fowle; Jeremy B. Fein

2000-01-01

353

Inorganic-ion resistance by bacteria isolated from a Mexico City freeway  

Microsoft Academic Search

Bacteria were isolated from soil samples, containing high exchangeable lead concentrations, obtained from a busy freeway in the México City metropolitan area. Forty-five selected strains (86.7% Gram-positive) had a single MIC distribution pattern for lead (800–1600 µg\\/ml lead nitrate) and were considered lead-resistant. The isolates showed variable levels of resistance to arsenate (86.7%), chromate (66.7%), cadmium (57.6%), and mercury (31.1%)

Sergio Vaca Pacheco; Rafil Miranda; Carlos Cervantes

1995-01-01

354

Comparative activity of the quinolones against anaerobic bacteria isolated at community hospitals.  

PubMed Central

The in vitro activity of five quinolone compounds, amoxicillin, and clindamycin against 118 strains of anaerobic bacteria isolated at community hospitals was determined by an agar dilution method. Nalidixic acid and cinoxacin had poor activity, and norfloxacin and enoxacin showed relatively poor activity. Ciprofloxacin was active against Bacteroides fragilis, Fusobacterium species, Clostridium perfringens, and gram-positive cocci. At peak levels achievable in the feces, norfloxacin and enoxacin had moderate activity.

Goldstein, E J; Citron, D M

1985-01-01

355

Inducible bacteriophages from ruminal bacteria.  

PubMed

The incidence of temperate bacteriophage in a wide range of ruminal bacteria was investigated by means of induction with mitomycin C. Supernatant liquid from treated cultures was examined for phagelike particles by using transmission electron microscopy. Of 38 ruminal bacteria studied, nine organisms (23.7%) representing five genera (Eubacteria, Bacteroides, Butyrivibrio, Ruminococcus, and Streptococcus) produced phagelike particles. Filamentous particles from Butyrivibrio fibrisolvens are the first of this morphological type reported from ruminal bacteria. All of the other particles obtained possessed polyhedral heads and long, noncontractile tails (group B-type phage). The limited range of morphological types produced by mitomycin C induction cannot yet account for the much wider range of types found in ruminal contents by direct examination. The presence of viral genetic material in a significant percentage of the bacteria tested, as well as in a range of different genera, indicates that viral genetic material may be a normal constituent of the genome of appreciable numbers of ruminal bacteria. PMID:2504111

Klieve, A V; Hudman, J F; Bauchop, T

1989-06-01

356

Bacteria foraging in turbulent waters  

NASA Astrophysics Data System (ADS)

Marine bacteria are the Ocean's recyclers, contributing to as much as 50% of the productivity of the marine food web. Bacteria forage on patches of dissolved nutrients using chemotaxis, the ability to swim up chemical gradients. As turbulence is ubiquitous in the Ocean, it is important to understand how turbulent flow conditions affect bacterial foraging. We used three-dimensional, isotropic direct numerical simulations coupled with a bacterial transport equation to address this problem. After the flow is continuously forced until it reaches a steady state, microscale nutrient patches are injected into the turbulent flow, and stirring produces thin nutrient filaments. Two populations of bacteria compete against each other: one population is motile and chemotactic (`active'), the other is non-motile (`passive'). The distribution of both populations is initially uniform. Chemotaxis allows active bacteria to cluster near the center of the nutrient filaments, increasing their nutrient uptake relative to passive bacteria. Increasing the turbulence intensity increases the short-term chemotactic advantage by quickly producing large gradients in the nutrient concentration, but also leads to rapid mixing of the nutrient field, which makes the chemotactic advantage short-lived. The results suggest that the evolutionary advantage of chemotaxis, based on the increase in nutrient uptake relative to the energetic cost of swimming, strongly depends on the turbulence level.

Taylor, John; Tang, Wenbo; Stocker, Roman

2009-11-01

357

Photokilling of bacteria by curcumin in different aqueous preparations. Studies on curcumin and curcuminoids XXXVII.  

PubMed

Curcumin has potential as a photosensitiser (PS) in photodynamic therapy (PDT) for localised superficial infections. However, it is a challenge to make an optimal curcumin formulation in which curcumin has acceptable solubility and stability at physiological pH and combined with high selective phototoxic activity towards bacteria. In the present study, the phototoxic effects of curcumin against gram-negative and gram-positive bacteria were investigated in selected aqueous preparations. The gram-positive Enterococcus faecalis and Streptococcus intermedius and the gram-negative Escherichia coli were used as bacterial models. The bacteria were exposed to 1-25 microM curcumin solubilised in DMSO, cyclodextrines, liposomes and surfactants known to interfere with membranes. After 30 min incubation the bacteria were irradiated with fluorescent tubes emitting blue light (emission max 430 nm). The irradiance was 17 mW/cm2 and the radiant exposure (light dose) was 0.5-30J/cm2. The bacterial survival was calculated as a percentage compared to controls. Various post-irradiation incubation times were tested. Curcumin's native fluorescence was exploited in examination of curcumin uptake in or adherence to bacteria by fluorescence microscopy. Changes in post-irradiation incubation time, curcumin concentration, irradiation dose and preparation strongly influenced the phototoxic efficiency of curcumin in vitro. Aqueous preparations of DMSO, polyethyleneglycol and the pluronic block copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) were the most efficient vehicles for curcumin to exert photokilling of gram-positive and gram-negative bacteria. PMID:19947170

Haukvik, T; Bruzell, E; Kristensen, S; Tønnesen, H H

2009-10-01

358

Magnetic Microsphere-Based Methods to Study the Interaction of Teicoplanin with Peptides and Bacteria  

PubMed Central

Teicoplanin (teic) from Actinoplanes teichomyceticus is a glycopeptide antibiotic used to treat many gram-positive bacterial infections. Glycopeptide antibiotics inhibit the bacteria growth by binding to carboxy-terminal D-Ala-D-Ala intermediates in the peptidoglycan of cell wall of gram positive bacteria. In this paper we report the derivatization of magnetic microspheres with teic (teic-microspheres). Fluorescence based techniques have been developed to analyze the binding properties of the microspheres to two D-Ala-D-Ala terminus peptides. The dissociation constants for the binding of carboxyfluorescein labeled D-Ala-D-Ala-D-Ala to teic on microspheres is established via fluorometry and flow cytometry and was determined to be 0.5 × 10?6 and 3.0 × 10?6 M, respectively. Feasibility of utilizing microparticles with fluorescence methods to detect low levels (limit of bacterial detection was determined to be 200 colony forming units [cfu]) of gram-positive bacteria has been demonstrated. A simple microfluidic experiment is reported to demonstrate the possibility of developing microsphere based affinity assays to study peptide-antibiotic interaction.

Piyasena, Menake E.; Real, Lilian J.; Diamond, Rochelle A.; Xu, H. Howard; Gomez, Frank A.

2009-01-01

359

Radioresistant Bacteria Came From Mars?  

NASA Astrophysics Data System (ADS)

We propose that the radioresistant bacteria (i.e. Deinococcus radiodurans) has been originated on Mars. This bacteria possesses an ability which should have been ab- solutely "unnecessary" in the Earth environment. It can survive very high doses of the ionizing radiation. Our experiments demonstrate that different kinds of non- radioresistant bacteria are able to develop very high radioresistance ability also. To develop radioresistance we exposed different bacterial cultures to several dozens of cycles of high irradiation. Therefore, radioresistance is not a result of some early spontaneous bacterial mutation but rather a consequence of the very specific plane- tary environment. Polar regions of Mars are the most probable (if not the only) place in the Solar System for such a periodical high-dosage irradiation process. We pro- pose a plausible scenario of where and when such an adaptation process could have taken place and also discuss indirect arguments of the Martian origin of Deinococcus Radiodurans based on their specific genetic structure.

Pavlov, A.; Kalinin, V.; Konstantinov, A.; Shelegedin, V.

360

Antifungal activity of rhizospheric bacteria.  

PubMed

Fluorescent Pseudomonad spp. were isolated from the rhizosphere of potato plants (Algeria) by serial dilutions of rhizosphere soils on Kings B medium and were tested for their antifungal activity. The antifungal activity of the Pseudomonas isolated from Potatoes rhizosphere was tested against Pythium ultimum, Rhizoctonia solani and Fusarium oxysporum in dual culture with bacteria on PDA. The Petri dish was divided into tow, on one the bacteria was spread and on the opposite side fungal plugs were inoculated and incubated for one week. Fourteen bacteria were isolated; only one isolate inhibited the growth of Pythium ultimum, Rhizoctonia solani, Fusarium solani; Fusarium oxysporum f.sp. albedinis and Fusarium oxysporum f. sp. Lycopersici with inhibition zones of 39.9, 33.7, 30.8, 19.9 and 22.5 mm respectively. PMID:21534477

Mezaache, S; Guechi, A; Zerroug, M M; Strange, R N; Nicklin, J

2010-01-01

361

Envisaging bacteria as phage targets  

PubMed Central

It can be difficult to appreciate just how small bacteria and phages are or how large, in comparison, the volumes that they occupy. A single milliliter, for example, can represent to a phage what would be, with proper scaling, an “ocean” to you and me. Here I illustrate, using more easily visualized macroscopic examples, the difficulties that a phage, as a randomly diffusing particle, can have in locating bacteria to infect. I conclude by restating the truism that the rate of phage adsorption to a given target bacterium is a function of phage density, that is, titer, in combination with the degree of bacterial susceptibility to adsorption by an encountering phage.

Abedon, Stephen T.

2011-01-01

362

Assessing Chronological Aging in Bacteria  

PubMed Central

Bacteria, which are often considered as avid reproductive organisms under constant selective pressure to utilize available nutrients to proliferate, might seem an inappropriate model to study aging. However, environmental conditions are rarely supporting the exponential growth that is most often studied in laboratories. In the wild, Escherichia coli inhabits environments of relative nutritional paucity. Not surprisingly, under such circumstances, members of an E. coli population age and progressively lose the ability to reproduce, even when environmental conditions provide such an opportunity. Here, we review the methods to study chronological aging in bacteria and some of the mechanisms that may contribute to their age-dependent loss of viability.

Gonidakis, Stavros; Longo, Valter D.

2014-01-01

363

Bacteria Living in Extreme Environments  

NSDL National Science Digital Library

In this activity, students will develop an experiment that will test the ability of bacteria to survive various temperature extremes. They will grow the bacteria in nutrient broth, which will be placed in different temperatures for at least 24 hours and then spread on nutrient agar plates and incubated at 37 degrees Celcius for an additional 24 hours. Students will: learn how to formulate and test their own experimental questions; learn sterile technique; gather and analyze data collected from their experiments; propose ideas/questions for further experimentation; and develop and improve their communication skills as they present results to their peers.

Zwanzig, Glenn

364

Metabolic versatility of Gram-positive microbial isolates from contaminated river sediments.  

PubMed

Gram-positive bacteria from river sediments affected by the proximity of a petrochemical industrial site were isolated and characterized with respect to their ability to degrade a wide range of aromatic compounds. In this study we identified metabolically diverse Gram-positive bacteria capable of growth on wide range aromatic compounds in the presence of heavy metals and with the ability to accumulate biopolymers. Thirty-four isolates that were able to use 9 or more common aromatic pollutants, such as benzene, biphenyl, naphthalene etc. as a sole source of carbon and energy included members of Bacillus, Arthrobacter, Rhodococcus, Gordonia, Streptomyces, and Staphylococcus genus. Rhodococcus sp. TN105, Gordonia sp. TN103 and Arthrobacter sp. TN221 were identified as novel strains. Nine isolates were able to grow in the presence of one or more metals (mercury, cadmium, nickel) at high concentration (100mM). Seven isolates could degrade 15 different aromatic compounds and could grow in the presence of one or more heavy metals. Two of these isolates were resistant to multiple antibiotics including erythromycin and nalidixic acid. One third of isolates could accumulate at least one biopolymer. Twelve isolates (mainly Bacillus sp. and Arthrobacter sp.) accumulated polyphosphate, 3 Bacillus sp. accumulated polyhydroxybutyrate, while 4 isolates could accumulate exopolysaccharides. PMID:22421345

Narancic, Tanja; Djokic, Lidija; Kenny, Shane T; O'Connor, Kevin E; Radulovic, Vanja; Nikodinovic-Runic, Jasmina; Vasiljevic, Branka

2012-05-15

365

A novel, nested, multiplex, real-time PCR for detection of bacteria and fungi in blood  

PubMed Central

Background The study describes the application of the PCR method for the simultaneous detection of DNA of Gram-negative bacteria, Gram-positive bacteria, yeast fungi and filamentous fungi in blood and, thus, a whole range of microbial etiological agents that may cause sepsis. Material for the study was sterile blood inoculated with four species of microorganisms (Escherichia coli, Staphylococcus aureus, Candida albicans and Aspergillus fumigatus) and blood collected from patients with clinical symptoms of sepsis. The developed method is based on nested-multiplex real-time PCR . Results Analysis of the obtained data shows that sensitivity of nested-multiplex real-time PCR remained at the level of 101 CFU/ml for each of the four studied species of microorganisms and the percentage of positive results of the examined blood samples from the patients was 70% and 19% for the microbiological culture method. The designed primers correctly typed the studied species as belonging to the groups of Gram-positive bacteria, Gram-negative bacteria, yeast fungi, or filamentous fungi. Conclusions Results obtained by us indicated that the designed PCR methods: (1) allow to detect bacteria in whole blood samples, (2) are much more sensitive than culture method, (3) allow differentiation of the main groups of microorganisms within a few hours.

2014-01-01

366

Aggregation Patterns in Stressed Bacteria  

Microsoft Academic Search

We study the formation of spot patterns seen in bacterial colonies when the bacteria are subjected to oxidative stress due to hazardous by-products of respiration. The cell density is coupled to a chemoattractant concentration as well as to nutrient and waste fields. The model combines the propagation of a front of motile bacterial radially outward from an initial site, a

Lev Tsimring; Herbert Levine; Igor Aranson; Eshel Ben-Jacob; Inon Cohen; Ofer Shochet; William N. Reynolds

1995-01-01

367

Clinical Applications of Probiotic Bacteria  

Microsoft Academic Search

Probiotic bacteria are applied to balance disturbed intestinal microflora and related dysfunctions of the gastrointestinal tract. Current clinical applications include well-documented areas such as treatment of acute rotavirus diarrhoea, lactose maldigestion, constipation, colonic disorders and side-effects of pelvic radiotherapy, and more recently, food allergy including milk hypersensitivity and changes associated with colon cancer development. Many novel probiotics appear to be

S. Salminen; A. C. Ouwehand; E. Isolauri

1998-01-01

368

Synthetic Biology in Streptomyces Bacteria  

Microsoft Academic Search

Actinomycete bacteria of the genus Streptomyces are major producers of bioactive compounds for the biotechnology industry. They are the source of most clinically used antibiotics, as well as of several widely used drugs against common diseases, including cancer . Genome sequencing has revealed that the potential of Streptomyces species for the production of valuable secondary metabolites is even larger than

Marnix H. Medema; Rainer Breitling; Eriko Takano

2011-01-01

369

Are extreme halophiles actually 'bacteria'  

NASA Technical Reports Server (NTRS)

Comparative cataloging of the 16S rRNA of Halobacterium halobium indicates that the organism did not arise, as a halophilic adaptation, from some typical bacterium. Rather, H. halobium is a member of the Archaebacteria, an ancient group of organisms that are no more related to typical bacteria than they are to eucaryotes.

Magrum, L. J.; Luehrsen, K. R.; Woese, C. R.

1978-01-01

370

Bacteriophytochromes in anoxygenic photosynthetic bacteria  

Microsoft Academic Search

Since the first discovery of a bacteriophytochrome in Rhodospirillum centenum, numerous bacteriophytochromes have been identified and characterized in other anoxygenic photosynthetic bacteria. This review\\u000a is focused on the biochemical and biophysical properties of bacteriophytochromes with a special emphasis on their roles in\\u000a the synthesis of the photosynthetic apparatus.

Eric Giraud; André Verméglio

2008-01-01

371

Raman spectroscopy of oral bacteria  

NASA Astrophysics Data System (ADS)

Raman spectroscopy has been employed to measure the varying concentrations of two oral bacteria in simple mixtures. Evaporated droplets of centrifuged mixtures of Streptococcus sanguis and Streptococcus mutans were analyzed via Raman microspectroscopy. The concentration of s. sanguis was determined based upon the measured Raman spectrum, using partial least squares cross-validation, with an r2 value of 0.98.

Berger, Andrew J.; Zhu, Qingyuan; Quivey, Robert G.

2003-10-01

372

Photosynthetic reaction centers in bacteria  

SciTech Connect

The photochemistry of photosynthesis begins in complexes called reaction centers. These have become model systems to study the fundamental process by which plants and bacteria convert and store solar energy as chemical free energy. In green plants, photosynthesis occurs in two systems, each of which contains a different reaction center, working in series. In one, known as photosystem 1, oxidized nicotinamide adenine dinucleotide phosphate (NADP[sup +]) is reduced to NADPH for use in a series of dark reactions called the Calvin cycle, named for Nobel Laureate Melvin Calvin, by which carbon dioxide is converted into useful fuels such as carbohydrates and sugars. In the other half of the photosynthetic machinery of green plants, called photosystem 2, water is oxidized to produce molecular oxygen. A different form of photosynthesis occurs in photosynthetic bacteria, which typically live at the bottom of ponds and feed on organic debris. Two main types of photosynthetic bacteria exist: purple and green. Neither type liberates oxygen from water. Instead, the bacteria feed on organic media or inorganic materials, such as sulfides, which are easier to reduce or oxidize than carbon dioxide or water. Perhaps in consequence, their photosynthetic machinery is simpler than that of green, oxygen-evolving plants and their primary photochemistry is better understood.

Norris, J.R. (Argonne National Lab., IL (United States) Univ. of Chicago, IL (United States)); Schiffer, M. (Argonne National Lab., IL (United States))

1990-07-30

373

Living bacteria in silica gels  

Microsoft Academic Search

The encapsulation of enzymes within silica gels has been extensively studied during the past decade for the design of biosensors and bioreactors. Yeast spores and bacteria have also been recently immobilized within silica gels where they retain their enzymatic activity, but the problem of the long-term viability of whole cells in an inorganic matrix has never been fully addressed. It

Nadine Nassif; Odile Bouvet; Marie Noelle Rager; Cécile Roux; Thibaud Coradin; Jacques Livage

2002-01-01

374

Nitrate, bacteria and human health  

Microsoft Academic Search

Nitrate is generally considered a water pollutant and an undesirable fertilizer residue in the food chain. Research in the 1970s indicated that, by reducing nitrate to nitrite, commensal bacteria might be involved in the pathogenesis of gastric cancers and other malignancies, as nitrite can enhance the generation of carcinogenic N-nitrosamines. More recent studies indicate that the bacterial metabolism of nitrate

Eddie Weitzberg; Jeff A. Cole; Nigel Benjamin; Jon O. Lundberg

2004-01-01

375

Studies on Dibenzothiophene Degrading Bacteria.  

National Technical Information Service (NTIS)

We are studying the interaction of several bacterial isolates with dibenzothiophene (DBT), a sulfur-containing model compound similar to some of the sulfur-containing components of fossil fuels. The goal is to use these bacteria for microbiological coal d...

D. H. Key M. S. Willey R. S. Kase T. E. Ward

1989-01-01

376

Role of Bacteria in Oncogenesis  

PubMed Central

Summary: Although scientific knowledge in viral oncology has exploded in the 20th century, the role of bacteria as mediators of oncogenesis has been less well elucidated. Understanding bacterial carcinogenesis has become increasingly important as a possible means of cancer prevention. This review summarizes clinical, epidemiological, and experimental evidence as well as possible mechanisms of bacterial induction of or protection from malignancy.

Chang, Alicia H.; Parsonnet, Julie

2010-01-01

377

Enzymatic Studies on Thermophilic Bacteria.  

National Technical Information Service (NTIS)

The objectives of the research were (1) to prepare crystalline alpha-amylase from thermophilic bacteria and to study the physical and chemical properties of the preparations in order to obtain data relative to the problem of thermal stability; (2) to stud...

L. L. Campbell

1964-01-01

378

Hydrocarbon degradation by antarctic bacteria  

SciTech Connect

Bacterial cultures obtained from sediment samples collected during a trial oil spill experiment conducted at Airport beach, Eastern Antarctica were selectively enriched for n-alkane-degrading and phenanthrenedegrading bacteria. Samples were collected from a control site and sites treated with different hydrocarbon mixtures - Special Antarctic blend (SAB), BP-Visco and orange roughy oils. One set of replicate sites was also treated with water from Organic Lake which had previously been shown to contain hydrocarbon-degrading bacteria. No viable bacteria were obtained from samples collected from sites treated with orange roughy oil. Extensive degradation of n-alkanes by enrichment cultures obtained from sites treated with SAB and BP-Visco occurred at both 25{degrees}C and 10{degrees}C. Extensive degradation of phenanthrene also occurred in enrichment cultures from these sites grown at 25{degrees}C. Concurrent increases of polar lipid in these cultures were also observed. The presence of 1,4-naphthaquinone and 1-naphthol during the growth of the cultures on phenanthrene is unusual and warrants further investigation of the mechanism of phenanthrene-degradation by these Antarctic bacteria.

Cavanagh, J.A.E.; Nichols, P.D.; McMeekin, T.A.; Franzmann, P.D. [Univ. of Tasmania (Australia)] [and others

1996-12-31

379

Probing the relationship between Gram-negative and Gram-positive S1 proteins by sequence analysis  

PubMed Central

Escherichia coli ribosomal protein S1 is required for the translation initiation of messenger RNAs, in particular when their Shine–Dalgarno sequence is degenerated. Closely related forms of the protein, composed of the same number of domains (six), are found in all Gram-negative bacteria. More distant proteins, generally formed of fewer domains, have been identified, by sequence similarities, in Gram-positive bacteria and are also termed ‘S1 proteins’. However in the absence of functional information, it is generally difficult to ascertain their relationship with Gram-negative S1. In this article, we report the solution structure of the fourth and sixth domains of the E. coli protein S1 and show that it is possible to characterize their ?-barrel by a consensus sequence that allows a precise identification of all domains in Gram-negative and Gram-positive S1 proteins. In addition, we show that it is possible to discriminate between five domain types corresponding to the domains 1, 2, 3, 4–5 and 6 of E. coli S1 on the basis of their sequence. This enabled us to identify the nature of the domains present in Gram-positive proteins and, subsequently, to probe the filiations between all forms of S1.

Salah, Philippe; Bisaglia, Marco; Aliprandi, Pascale; Uzan, Marc; Sizun, Christina; Bontems, Francois

2009-01-01

380

Rhs proteins from diverse bacteria mediate intercellular competition.  

PubMed

Rearrangement hotspot (Rhs) and related YD-peptide repeat proteins are widely distributed in bacteria and eukaryotes, but their functions are poorly understood. Here, we show that Gram-negative Rhs proteins and the distantly related wall-associated protein A (WapA) from Gram-positive bacteria mediate intercellular competition. Rhs and WapA carry polymorphic C-terminal toxin domains (Rhs-CT/WapA-CT), which are deployed to inhibit the growth of neighboring cells. These systems also encode sequence-diverse immunity proteins (RhsI/WapI) that specifically neutralize cognate toxins to protect rhs(+)/wapA(+) cells from autoinhibition. RhsA and RhsB from Dickeya dadantii 3937 carry nuclease domains that degrade target cell DNA. D. dadantii 3937 rhs genes do not encode secretion signal sequences but are linked to hemolysin-coregulated protein and valine-glycine repeat protein G genes from type VI secretion systems. Valine-glycine repeat protein G is required for inhibitor cell function, suggesting that Rhs may be exported from D. dadantii 3937 through a type VI secretion mechanism. In contrast, WapA proteins from Bacillus subtilis strains appear to be exported through the general secretory pathway and deliver a variety of tRNase toxins into neighboring target cells. These findings demonstrate that YD-repeat proteins from phylogenetically diverse bacteria share a common function in contact-dependent growth inhibition. PMID:23572593

Koskiniemi, Sanna; Lamoureux, James G; Nikolakakis, Kiel C; t'Kint de Roodenbeke, Claire; Kaplan, Michael D; Low, David A; Hayes, Christopher S

2013-04-23

381

Barbecue Bliss: Keeping Bacteria at Bay  

MedlinePLUS

... Blood & Biologics Articulos en Espanol Barbecue Bliss: Keeping Bacteria at Bay Search the Consumer Updates Section Get ... your list. Summer brings out barbecue grills—and bacteria, which multiply in food faster in warm weather ...

382

Novel antimicrobial peptides that inhibit gram positive bacterial exotoxin synthesis.  

PubMed

Gram-positive bacteria, such as Staphylococcus aureus, cause serious human illnesses through combinations of surface virulence factors and secretion of exotoxins. Our prior studies using the protein synthesis inhibitor clindamycin and signal transduction inhibitors glycerol monolaurate and ?-globin and ?-globin chains of hemoglobin indicate that their abilities to inhibit exotoxin production by S. aureus are separable from abilities to inhibit growth of the organism. Additionally, our previous studies suggest that inhibition of exotoxin production, in absence of ability to kill S. aureus and normal flora lactobacilli, will prevent colonization by pathogenic S. aureus, while not interfering with lactobacilli colonization. These disparate activities may be important in development of novel anti-infective agents that do not alter normal flora. We initiated studies to explore the exotoxin-synthesis-inhibition activity of hemoglobin peptides further to develop potential agents to prevent S. aureus infections. We tested synthesized ?-globin chain peptides, synthetic variants of ?-globin chain peptides, and two human defensins for ability to inhibit exotoxin production without significantly inhibiting S. aureus growth. All of these peptides were weakly or not inhibitory to bacterial growth. However, the peptides were inhibitory to exotoxin production with increasing activity dependent on increasing numbers of positively-charged amino acids. Additionally, the peptides could be immobilized on agarose beads or have amino acid sequences scrambled and still retain exotoxin-synthesis-inhibition. The peptides are not toxic to human vaginal epithelial cells and do not inhibit growth of normal flora L. crispatus. These peptides may interfere with plasma membrane signal transduction in S. aureus due to their positive charges. PMID:24748386

Merriman, Joseph A; Nemeth, Kimberly A; Schlievert, Patrick M

2014-01-01

383

Bacteria as food for marine harpacticoid copepods  

Microsoft Academic Search

Feeding experiments were carried out on the harpacticoid copepods Tisbe holothuriae and Paramphiascella vararensis, using various species of marine and brackish water bacteria as food. Short-term experiments with 3H-labelled bacteria are described, as well as experiments covering longer periods of time using non-labelled, dried bacteria. Results show that for both T. holothuriae and P. vararensis, the amount of dry bacteria

M. Rieper

1978-01-01

384

An effort to make sense of antisense transcription in bacteria  

PubMed Central

Analysis of bacterial transcriptomes have shown the existence of a genome-wide process of overlapping transcription due to the presence of antisense RNAs, as well as mRNAs that overlapped in their entire length or in some portion of the 5?- and 3?-UTR regions. The biological advantages of such overlapping transcription are unclear but may play important regulatory roles at the level of transcription, RNA stability and translation. In a recent report, the human pathogen Staphylococcus aureus is observed to generate genome-wide overlapping transcription in the same bacterial cells leading to a collection of short RNA fragments generated by the endoribonuclease III, RNase III. This processing appears most prominently in Gram-positive bacteria. The implications of both the use of pervasive overlapping transcription and the processing of these double stranded templates into short RNAs are explored and the consequences discussed.

Lasa, Inigo; Toledo-Arana, Alejandro; Gingeras, Thomas R.

2012-01-01

385

In vitro activities of a new lipopeptide, HMR 1043, against susceptible and resistant gram-positive isolates.  

PubMed

The purpose of this study was to compare the activity of HMR 1043 with those of daptomycin and teicoplanin against gram-positive isolates. Susceptibility tests were performed for 52 strains, 26 parental strains, including staphylococcal, streptococcal, enterococcal, and listerial strains, and 26 HMR 1043-resistant mutants obtained from parental strains by using the Szybalski method. Agar dilution and disk diffusion susceptibility tests were performed by the procedures outlined by the NCCLS. HMR 1043 demonstrated good activity against susceptible and resistant gram-positive bacteria. The activity of HMR 1043 in vitro was less influenced by the presence of calcium ions than that of daptomycin. Susceptibility test breakpoints were not defined because of the poor correlation coefficients obtained with the different disks tested. PMID:12937020

Bemer, Pascale; Juvin, Marie-Emmanuelle; Bryskier, Andre; Drugeon, Henri

2003-09-01

386

In Vitro Activities of a New Lipopeptide, HMR 1043, against Susceptible and Resistant Gram-Positive Isolates  

PubMed Central

The purpose of this study was to compare the activity of HMR 1043 with those of daptomycin and teicoplanin against gram-positive isolates. Susceptibility tests were performed for 52 strains, 26 parental strains, including staphylococcal, streptococcal, enterococcal, and listerial strains, and 26 HMR 1043-resistant mutants obtained from parental strains by using the Szybalski method. Agar dilution and disk diffusion susceptibility tests were performed by the procedures outlined by the NCCLS. HMR 1043 demonstrated good activity against susceptible and resistant gram-positive bacteria. The activity of HMR 1043 in vitro was less influenced by the presence of calcium ions than that of daptomycin. Susceptibility test breakpoints were not defined because of the poor correlation coefficients obtained with the different disks tested.

Bemer, Pascale; Juvin, Marie-Emmanuelle; Bryskier, Andre; Drugeon, Henri

2003-01-01

387

Sulfur metabolism in bacteria associated with cheese  

Microsoft Academic Search

Metabolism of sulfur in bacteria associated with cheese has long been a topic of interest. Volatile sulfur compounds, specifically methanethiol, are correlated to desirable flavor in Cheddar cheese, but their definitive role remains elusive. Only recently have enzymes been found that produce this compound in bacteria associated with cheese making. Cystathionine ß- and ?-lyase are found in lactic acid bacteria

Bart Weimer; Kimberly Seefeldt; Benjamin Dias

1999-01-01

388

Faecal indicator bacteria at fish farms  

Microsoft Academic Search

The observed concentrations of bacteria at two large fish farms were not high, but due to the great volume of the discharge the total amount of bacteria was large. Total coliform (TC) bacteria identified belonged mainly to the genera Enterobacter, Citrobacter and Aeromonas. The majority of faecal coliform (FC) strains were Escherichia coli. E. coli was absent, or occurred at

Maarit Niemi; Irmeli Taipalinen

1982-01-01

389

Bacteriophages that infect Bacillus bacteria (Anthrax)  

US Patent & Trademark Office Database

The invention provides bacteriophages that infect Bacillus bacteria, including Bacillus anthracis, and compositions containing the bacteriophages. The invention also provides methods for using the bacteriophages of the invention to prevent and treat infection of an organism by Bacillus bacteria. Methods and materials to decontaminate a surface or an organism that is contaminated with Bacillus bacteria or Bacillus spores is also provided.

2008-05-20

390

Regulated RNA stability in the Gram positives  

PubMed Central

Regulation of bacterial gene expression at the post-transcriptional level has emerged as a major control mechanism, although not yet as well recognized as the mechanisms of control at the transcriptional level. In this article, we focus on regulated RNA decay in the control of gene expression in Gram-positive organisms, with a focus on Bacillus subtilis. Discovery of new ribonuclease activities in B. subtilis and other Gram-positive species, especially the dual-functioning RNase J1, which specifies both an endonuclease activity and the long-sought bacterial 5’-to-3’ exoribonuclease activity, has led to the recognition of intriguing mechanisms of gene regulation at the level of RNA decay.

Condon, Ciaran; Bechhofer, David H.

2011-01-01

391

Heparinase production by anaerobic bacteria.  

PubMed Central

The production of heparinase by a wide range of anaerobic bacteria isolated from clinical specimens was investigated. None of the 29 strains of Bacteroides fragilis produced heparinase. Of 62 other Bacteroides tested, only two of four strains of B ovatus, two of three strains of B thetaiotaomicron, and two of four strains of B uniformis were heparinase producers. None of the 48 strains of fusobacteria or seven strains of Veillonella produced heparinase. The anaerobic cocci (19 peptococci and seven peptostreptococci) were also negative for heparinase production as were 46 Clostridium spp tested. It was concluded that heparinase production by anaerobic bacteria was unlikely to play a part in the regional thrombophlebitis that sometimes occurs in anaerobic infections.

Riley, T V

1987-01-01

392

Genetics of Lactic Acid Bacteria  

NASA Astrophysics Data System (ADS)

Many meat (or fish) products, obtained by the fermentation of meat originating from various animals by the flora that naturally contaminates it, are part of the human diet since millenaries. Historically, the use of bacteria as starters for the fermentation of meat, to produce dry sausages, was thus performed empirically through the endogenous micro-biota, then, by a volunteer addition of starters, often performed by back-slopping, without knowing precisely the microbial species involved. It is only since about 50 years that well defined bacterial cultures have been used as starters for the fermentation of dry sausages. Nowadays, the indigenous micro-biota of fermented meat products is well identified, and the literature is rich of reports on the identification of lactic acid bacteria (LAB) present in many traditional fermented products from various geographical origin, obtained without the addition of commercial starters (See Talon, Leroy, & Lebert, 2007, and references therein).

Zagorec, Monique; Anba-Mondoloni, Jamila; Coq, Anne-Marie Crutz-Le; Champomier-Vergès, Marie-Christine

393

Viability of bacteria in peatlands  

NASA Astrophysics Data System (ADS)

The viability of bacteria in oligotrofic bogs and fens was determined by the luminescent microscopy method with the help of a two-component fluorescent dye (L7012 LIVE/DEAD). Living bacterial cells were found in the entire peat profiles. Their portion was maximal (up to 60%) in the upper layers and did not exceed 25% in the lower layers. The portion of dead bacterial cells varied from 3 to 19%, and dormant cells constituted 25 to 95% of the total number of bacterial cells. The numbers of dormant cells increased down the profiles irrespectively of the peat type. The portion of nanoforms did not exceed 5% of the total. The cells of the nanoforms, unlike the bacteria of typical sizes, were characterized by their high viability (93-98%).

Bogdanova, O. Yu.; Golovchenko, A. V.; Lysak, L. V.; Glukhova, T. V.; Zvyagintsev, D. G.

2014-04-01

394

Anaerobic bacteria from hypersaline environments.  

PubMed

Strictly anaerobic halophiles, namely fermentative, sulfate-reducing, homoacetogenic, phototrophic, and methanogenic bacteria are involved in the oxidation of organic carbon in hypersaline environments. To date, six anaerobic fermentative genera, containing nine species, have been described. Two of them are homoacetogens. Six species belong to the family Haloanaerobiaceae, as indicated by their unique 16S rRNA oligonucleotide sequences. Desulfohalobium retbaense and Desulfovibrio halophilus represent the only two moderately halophilic sulfate reducers so far reported. Among anoxygenic phototrophic anaerobes, a few purple bacteria with optimal growth at salinities between 6 and 11% NaCl have been isolated from hypersaline habitats. They belong to the genera Rhodospirillum, Chromatium, Thiocapsa, and Ectothiorhodospira. The commonest organisms isolated so far are Chromatium salexigens, Thiocapsa halophila, and Rhodospirillum salinarum. Extremely halophilic purple bacteria have most commonly been isolated from alkaline brines and require about 20 to 25% NaCl for optimal growth. They belong to the family Ectothiorodhospiraceae. Their osmoregulation involves synthesis or uptake of compatible solutes such as glycine-betaine that accumulate in their cytoplasm. The existence of methanogens in hypersaline environments is related to the presence of noncompetitive substrates such as methylamines, which originate mainly from the breakdown of osmoregulatory amines. Methanogenesis probably does not contribute to the mineralization of carbohydrates at NaCl concentrations higher than 15%. Above this concentration, sulfate reduction is probably the main way to oxidize H2 (although at rates too low to use up all the H2 formed) and occupies a terminal function kn the degradation of carbohydrates. Three genera and five species of halophilic methylotrophic methanogens have been reported. A bloom of phototrophic bacteria in the marine salterns of Salins-de-Giraud, located on the Mediterranean French coast in the Rhone Delta, is also described. PMID:8177169

Ollivier, B; Caumette, P; Garcia, J L; Mah, R A

1994-03-01

395

Studies on dibenzothiophene degrading bacteria  

Microsoft Academic Search

We are studying the interaction of several bacterial isolates with dibenzothiophene (DBT), a sulfur-containing model compound similar to some of the sulfur-containing components of fossil fuels. The goal is to use these bacteria for microbiological coal desulfurization. Approximately 20 strains that metabolize DBT have been identified using an assay based on the oxidation\\/reduction indicator dye triphenyltetrazolium chloride (TTC). These isolates

D. H. Key; M. S. Willey; R. S. Kase; T. E. Ward

1989-01-01

396

Transposon mutagenesis of coryneform bacteria  

Microsoft Academic Search

The Corynebacterium glutamicum insertion sequence IS31831 was used to construct two artificial transposons: Tn31831 and miniTn31831. The transposition vectors were based on a gram-negative replication origin and do not replicate in coryneform bacteria. Strain Brevibacterium flavum MJ233C was mutagenized by miniTn31831 at an efficiency of 4.3 x 104 mutants per microgram DNA. Transposon insertions occurred at different locations on the

Alain A. Vertès; Yoko Asai; Masayuki Inui; Miki Kobayashi; Yasurou Kurusu; Hideaki Yukawa

1994-01-01

397

Bacteria under simulated Martian conditions.  

PubMed

The behavior of organisms in simulated Martian conditions is of great importance to exobiology for two reasons: (1) Because of the extreme environment of Mars, the likelihood of contamination of the planet by earth organisms is considered slight by some scientists. To date, there has been little evidence to contradict this supposition. Such evidence is presented. (2) The selection and adaptation of earth bacteria to Martian conditions is potentially significant in understanding Martian life, if it exists, and may be helpful in designing life-detection techniques and devices. Of course, simulation attempts, based on current knowledge of the Mars environment, may be far from the actual conditions, and extrapolations made from such situations of no real significance. However, generalizations can be made and cautious interpretation of the results of those experiments seems well worth reporting. A new technique for simulation of known parameters of the Martian environment is discussed along with possible biological implications. The response of bacteria to such simulation is demonstrated in terms of survival and growth, showing that certain bacteria will not only survive, but grow during simulated Martian freeze-thaw cycling if water is present. Ways are demonstrated in which water can be present on Mars although not detectable with current technology. Plans for future experimentation are discussed. PMID:11881642

Young, R S; Deal, P H; Bell, J; Allen, J L

1964-01-01

398

Photochemical inactivation of pathogenic bacteria in human platelet concentrates.  

PubMed

Platelet concentrates (PC) may be infrequently contaminated with low levels of bacteria that can cause septicemia and death in patients receiving transfusion therapy. We evaluated the efficacy of a photochemical decontamination (PCD) technique using 8-methoxypsoralen (8-MOP) and long wavelength UV light (UVA) to inactivate bacteria in standard therapeutic PC. Twelve phylogenetically distinct pathogenic bacteria, 5 gram-positive and 7 gram-negative organisms, were seeded into PC to a final challenge dose ranging from 10(5) to 10(7) colony-forming units (CFU)/mL. Contaminated PC were treated with 8-MOP (5 micrograms/mL) and 5 J/cm2 of UVA, a PCD treatment regimen found to adequately preserve in vitro platelet function. Greater than 10(5) CFU/mL of all 5 gram-positive (Staphylococcus aureus, Streptococcus epidermidis, Streptococcus pyogenes, Listeria monocytogenes, and Corynebacterium minutissimum) and 2 of the gram-negative (Escherichia coli and Yersinia enterocolitica) organisms were inactivated. The remaining 5 gram-negative organisms were more resistant, with less than 10(1) to 10(3.7) CFU/mL inactivated under these conditions. The inactivation efficiency for this resistant group of gram-negative organisms was improved when PC were resuspended in a synthetic storage medium with reduced plasma protein concentration (15%) and an increased 8-MOP concentration (23.4 micrograms/mL). Illumination with 3 J/cm2 of UVA in this system inactivated greater than 10(5) CFU/mL of 4 resistant gram-negative organisms (Salmonella choleraesuis, Enterobacter cloacae, Serratia marcescens, and Klebsiella pneumoniae) and 10(4.1) CFU/mL of the most resistant gram-negative organism (Pseudomonas aeruginosa). This level of PCD treatment did not adversely affect in vitro platelet function. These results demonstrate that PCD using 8-MOP (5 to 23.4 micrograms/mL) effectively inactivated high levels of pathogenic bacteria in PC with adequate preservation of in vitro platelet properties. PMID:8167348

Lin, L; Londe, H; Janda, J M; Hanson, C V; Corash, L

1994-05-01

399

Magnetic microsphere-based methods to study the interaction of teicoplanin with peptides and bacteria.  

PubMed

Teicoplanin (teic) from Actinoplanes teichomyceticus is a glycopeptide antibiotic used to treat many gram-positive bacterial infections. Glycopeptide antibiotics inhibit bacterial growth by binding to carboxy-terminal D-Ala-D-Ala intermediates in the peptidoglycan of the cell wall of gram-positive bacteria. In this paper we report the derivatization of magnetic microspheres with teic (teic-microspheres). Fluorescence-based techniques have been developed to analyze the binding properties of the microspheres to two D-Ala-D-Ala terminus peptides. The dissociation constant for the binding of carboxyfluorescein-labeled D-Ala-D-Ala-D-Ala to teic on microspheres was established via fluorimetry and flow cytometry and was determined to be 0.5 x 10(-6) and 3.0 x 10(-6) mol L(-1), respectively. The feasibility of utilizing microparticles with fluorescence methods to detect low levels (the limit of bacterial detection was determined to be 30 colon-forming units; cfu) of gram-positive bacteria has been demonstrated. A simple microfluidic experiment is reported to demonstrate the possibility of developing microsphere-based affinity assays to study peptide-antibiotic interaction. PMID:18712518

Piyasena, Menake E; Real, Lilian J; Diamond, Rochelle A; Xu, H Howard; Gomez, Frank A

2008-11-01

400

AIDS: "it's the bacteria, stupid!".  

PubMed

Acid-fast tuberculous mycobacterial infections are common in AIDS and are regarded as secondary "opportunistic infections." According to the National Institute of Allergy and Infectious Diseases, TB is the major attributable cause of death in AIDS patients. Could such bacteria play a primary or causative role in AIDS? Certainly, In screening tests for HIV, there is frequent, up to 70%, cross-reactivity, between the gag and pol proteins of HIV and patients with mycobacterial infections such as tuberculosis. By 1972, five years before gays started dying in the U.S., Rolland wrote Genital Tuberculosis, a Forgotten Disease? And ironically, in 1979, on the eve of AIDS recognition, Gondzik and Jasiewicz showed that even in the laboratory, genitally infected tubercular male guinea pigs could infect healthy females through their semen by an HIV-compatible ratio of 1 in 6 or 17%, prompting him to warn his patients that not only was tuberculosis a sexually transmitted disease, but also the necessity of the application of suitable contraceptives, such as condoms, to avoid it. Gondzik's solution and date of publication are chilling; his findings significant. Since 1982 Cantwell et al found acid-fast bacteria closely related to tuberculosis (TB) and atypical tuberculosis in AIDS tissue. On the other hand molecular biologist and virologist Duesberg, who originally defined retroviral ultrastructure, has made it clear that HIV is not the cause of AIDS and that the so-called AIDS retrovirus has never been isolated in its pure state. Dr. Etienne de Harven, first to examine retroviruses under the electron, agrees. In 1993 HIV co-discoverer Luc Montagnier reported on cell-wall-deficient (CWD) bacteria which he called "mycoplasma" in AIDS tissue. He suspected these as a necessary "co-factor" for AIDS. Remarkably, Montagnier remained silent on Cantwell's reports of acid-fast bacteria which could simulate "mycoplasma" in AIDS tissue. Mattman makes clear that the differentiation between mycoplasma and CWD bacteria is difficult at best and cites Pachas's 1985 study wherein one mycoplasma was actually mistaken for a CWD form of a bacterium closely related to the mycobacteria. It is important to realize that the statement "HIV is the sole cause of AIDS" is just a hypothesis. There are unanswered questions and controversy concerning the role of HIV "as the sole cause of AIDS." And until they are resolved, a cure is not possible. This paper explores the possible role of acid-fast tuberculous mycobacteria as "primary agents" in AIDS. PMID:18691828

Broxmeyer, Lawrence; Cantwell, Alan

2008-11-01

401

Differential effects of chlorination of bacteria on their capacity to generate NO, TNF-alpha and IL-6 in macrophages.  

PubMed Central

Activated rodent macrophages produce high amounts of nitric oxide (NO). NO as a tumoricidal and defence molecule against intracellular parasites is commonly accepted. However, its role as an obligatory killing factor for extracellular bacteria is controversial. In the present study we stimulated murine peritoneal macrophages by heat-killed bacteria (Staphylococcus aureus, S. epidermidis and Escherichia coli). In some groups bacteria were pretreated with HOCl, to replace the chlorinating system in activated neutrophils that operates as a bactericidal system in vivo. High levels of NO, tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were detected after stimulation by all non-chlorinated bacteria strains tested. However, after chlorination Gram-positive bacteria lost their ability to induce NO and TNF-alpha, whereas phagocytosis and IL-6 production were not affected by chlorination.

Marcinkiewicz, J; Czajkowska, B; Grabowska, A; Kasprowicz, A; Kociszewska, B

1994-01-01

402

Phylogenetic Diversity of Bacteria Associated with the Marine Sponge Gelliodes carnosa Collected from the Hainan Island Coastal Waters of the South China Sea  

Microsoft Academic Search

Several molecular techniques were employed to document the bacterial diversity associated with the marine sponge Gelliodes carnosa. Cultivation-dependent and cultivation-independent methods were used to obtain the 16S rRNA gene sequences of the bacteria.\\u000a Phylogenetic analysis based on the 16S rRNA gene sequences showed that the bacterial community structure was highly diverse\\u000a with representatives of the high G?+?C Gram-positive bacteria, cyanobacteria,

Chang-Qing Li; Wen-Chao Liu; Ping Zhu; Jin-Ling Yang; Ke-Di Cheng

403

A novel quantitative reverse-transcription PCR (qRT-PCR) for the enumeration of total bacteria, using meat micro-flora as a model  

Microsoft Academic Search

A sensitive quantitative reverse-transcription PCR (qRT-PCR) method was developed for enumeration of total bacteria. Using two sets of primers separately to target the ribonuclease-P (RNase P) RNA transcripts of gram positive and gram negative bacteria. Standard curves were generated using SYBR Green I kits for the LightCycler 2.0 instrument (Roche Diagnostics) to allow quantification of mixed microflora in liquid media.

Anthony Dolan; Catherine M. Burgess; Thomas B. Barry; Seamus Fanning; Geraldine Duffy

2009-01-01

404

Interactions of nisin and perdiocin PA1 with closely related lactic acid bacteria that manifest over hundred-fold differences in bacteriocin sensitivity  

Microsoft Academic Search

The natural variation in the susceptibilities of gram-positive bacteria towards the bacteriocins nisin and pediocin PA-1 is considerable. This study addresses the factors associated with this variability for closely related lactic acid bacteria. We compared two sets of nonbacteriocinogenic strains for which the MICs of nisin and pediocin PA-1 differed 100- to 1,000-fold: Lactobacillus sake DSM20017 and L. sake DSM20497

MARJON H. J. BENNIK; ANNETTE VERHEUL; TJAKKO ABEE; GEESJE NAAKTGEBOREN-STOFFELS; LEON G. M. GORRIS; EDDY J. SMID

1997-01-01

405

Characterization and evaluation of stress and heavy metal tolerance of some predominant Gram negative halotolerant bacteria from mangrove soils of Bhitarkanika, Orissa, India  

Microsoft Academic Search

In the present study both Gram positive and Gram negative bacteria were isolated using enrichment media from five different stations from mangroves soils of Bhitarkanika, Orissa, India. Among the bacterial populations studied, the Gram negative bacterial population was found to be more in all the stations. Out of several Gram negative bacterial isolates, six predominant and morphologically distinct isolates were

Rath B

406

Fate of pathogenic bacteria in microcosms mimicking human body sites.  

PubMed

During the infectious process, pathogens may reach anatomical sites where they are exposed to substances interfering with their growth. These substances can include molecules produced by the host, and his resident microbial population, as well as exogenous antibacterial drugs. Suboptimal concentrations of inhibitory molecules and stress conditions found in vivo (high or low temperatures, lack of oxygen, extreme pH) might induce in bacteria the activation of survival mechanisms blocking their division capability but allowing them to stay alive. These "dormant" bacteria can be reactivated in particular circumstances and would be able to express their virulence traits. In this study, it was evaluated the effect of some environmental conditions, such as optimal and suboptimal temperatures, direct light and antibiotic sub-inhibitory concentrations doses of antibiotic, on the human pathogens Escherichia coli and Enterococcus faecalis when incubated in fluids accumulated in the body of patients with different pathologies. It is shown that inoculation in a number of accumulated body fluids and the presence of gentamicin, reliable conditions encountered during pathological states, induce stress-responding strategies enabling bacteria to persist in microcosms mimicking the human body. Significant differences were detected in Gram-negative and Gram-positive species with E. faecalis surviving, as starved or viable but non-culturable forms, in any microcosm and condition tested and E. coli activating a viable but non-culturable state only in some clinical samples. The persistence of bacteria under these conditions, being non-culturable, might explain some recurrent infections without isolation of the causative agent after application of the standard microbiological methods. PMID:23657544

Castellani, Francesco; Ghidini, Valentina; Tafi, Maria Carla; Boaretti, Marzia; Lleo, Maria M

2013-07-01

407

Anti-infective Potential of Hot-spring Bacteria  

PubMed Central

Aim and Background: Antibiotic resistance currently spans most of the known classes of natural and synthetic antibiotics; limiting our options for treatment of infections and demanding discovery of new classes of antibiotics. Much effort is being directed towards developing new antibiotics to overcome this problem. Success in getting novel chemical entities from microbial sources depends essentially on novelty of its habitat. The diversity of geographical location decides the type of micro-flora. In the past various terrestrial and aqueous microorganisms have provided several novel bioactive secondary metabolites of pharmaceutical importance. Hot-springs have not been as extensively exploited as other terrestrial resources. However, perseverance with such microbes augment the probability of getting novel bioactive compounds. Materials and Methods: Hot-springs soil samples were collected from Hot-springs in Maharashtra. Actinomycetes and other eubacteria were isolated from these soil samples by selective methods and purified. They were classified based on gram's nature and morphology. Six representative morphological strains were screened for their anti-infective potential by agar well diffusion method as reported by Nathan P. et al (1974). The bioactivity of the active microbes was confirmed. Results: Seventy three strains of bacteria encompassing eight actinomycetes, and 65 eubacteria were isolated and purified. Among the actives eubacteria PPVWK106001 showed broad spectrum antibacterial activity encompassing both gram positive and gram negative bacterial test models. The extract was active against resistant bacteria such as MRSA and VREs. Activity was very specific as there was no activity against fungi even at 100 fold concentration. The active principle was extractable in butanol. Conclusions: The study showed that Hot-springs exhibit diverse bacteria and it serves as potential reservoirs for bacteria of antimicrobial importance with diverse facet of activities. Thus Hot-springs microbes have ability to address issue of resistant bugs.

Pednekar, Pallavi; Jain, Roopesh; Mahajan, Girish

2011-01-01

408

Glycerol Monolaurate Inhibits the Effects of Gram Positive Select Agents on Eukaryotic Cells†  

PubMed Central

Many exotoxins of gram positive bacteria, such as superantigens (staphylococcal enterotoxins, toxic shock syndrome toxin-1 [TSST-1], and streptococcal pyrogenic exotoxins) and anthrax toxin are bioterrorism agents that cause diseases by immunostimulation or cytotoxicity. Glycerol monolaurate (GML), a fatty acid monoester found naturally in humans, has been reported to prevent synthesis of gram positive bacterial exotoxins. This study explored the ability of GML to inhibit the effects of exotoxins on mammalian cells and prevent rabbit lethality from TSS. GML (?10 ug/ml) inhibited superantigen (5 ug/ml) immunoproliferation, as determined by inhibition of 3H-thymidine incorporation into DNA of human peripheral blood mononuclear cells (1 × 106 cells/ml) as well as phospholipase C?1, suggesting inhibition of signal transduction. The compound (20 ug/ml) prevented superantigen (100 ug/ml) induced cytokine secretion by human vaginal epithelial cells (HVECs) as measured by ELISA. GML (250 ug) inhibited rabbit lethality due to TSST-1 administered vaginally. GML (10 ug/ml) inhibited HVEC and macrophage cytotoxicity by anthrax toxin, prevented erythrocyte lysis by purified hemolysins (staphylococcal ? and ?) and culture fluids containing streptococcal and Bacillus anthracis hemolysins, and was non-toxic to mammalian cells (up to 100 ug/ml) and rabbits (250 ug). GML stabilized mammalian cell membranes, as erythrocyte lysis was reduced in the presence of hypotonic aqueous solutions (0 to 0.05 M saline) or staphylococcal ? and ?-hemolysins when erythrocytes were pretreated with GML. GML may be useful in management of gram positive exotoxin illnesses; its action appears to be membrane stabilization with inhibition of signal transduction.

Peterson, Marnie L.; Schlievert, Patrick M.

2008-01-01

409

Sarcina-like bacteria associated with bloat in young lambs and calves.  

PubMed

Sarcina species are fastidious Gram-positive anaerobic bacteria that occur in cubical packets of eight or more cells. In 2006 to 2007, they were associated with cases of acute abomasal bloat in young lambs and calves. Two incidents were in lambs aged three to six weeks that were found dead, with one or two cases in each of a group of 15 and 100 lambs. Three incidents were recorded in small groups of calves up to 10 days of age, two cases in each incident, with the calves found dead or dying after a short illness characterised by bloat. Their gross lesions included emphysema and oedema of the abomasal wall, mucosal hyperaemia and haemorrhage, and rupture of the abomasum. Histological lesions included abomasitis with congestion, haemorrhage, emphysema and oedema. Bacteria characteristic of Sarcina species were observed in sections associated with the superficial mucosa of these cases, but the bacteria were not detected in cultures. PMID:18820327

Edwards, G T; Woodger, N G A; Barlow, A M; Bell, S J; Harwood, D G; Otter, A; Wight, A R

2008-09-27

410

[Characteristics of bacteria isolated from body surface of German cockroaches caught in hospitals].  

PubMed

The objective of the study was to identify bacterial flora from external parts of German cockroaches caught in hospitals. The susceptibility of the bacteria to the most important groups of antimicrobial agents was also examined. 80 strains of bacteria were isolated, among them 34 strains of Gram-positive cocci and 31 strains of Gram-negative rods. One of isolated strains of Citrobacter freundii and two strains of Serratia liquefaciens showed ESBL mechanism of resistance and extended level of AmpC--type beta-lactamases. Two Staphylococcus strains (S. epidermidis and S. equorum) were resistant to erythromycin and clindamycin (MLSB mechanism of resistance). Such strains, resistant to antibiotics and chemiotherapeutics may be reservoirs of resistance genes which can be transmitted into other bacteria. Presence of such pathogens on the body surface of German cockroaches, very mobile insects, might create conditions for easy dissemination of them in hospital environment. PMID:15029841

Czajka, Ewa; Pancer, Katarzyna; Kochman, Maria; Gliniewicz, Aleksandra; Sawicka, Bozena; Rabczenko, Daniel; Stypu?kowska-Misiurewicz, Hanna

2003-01-01

411

Characterization of S. pneumoniae pneumonia-induced multiple organ dysfunction syndrome: an experimental mouse model of gram-positive sepsis.  

PubMed

Streptococcus pneumoniae, a gram-positive bacteria, is the most common cause of community-acquired pneumonia. It is a common cause of septic shock with multiple organ dysfunction syndrome (MODS) resulting in significant mortality. Gram-positive mouse models of sepsis with MODS are required to examine mechanisms of immune responses in severe sepsis. To assess whether lung infection due to S. pneumoniae in a nonventilated mouse model can induce multiple organ dysfunction. S. pneumoniae, SPN 15814 strain, harvested at log phase, was injected intratracheally in C57BL/6 mice at OD 600 between 0.35 and 0.63. A dose of bacteria at OD 600 = 0.63 conferred approximately 30% mortality in 36 h. Lung pneumonia was assessed by histology, lung myeloperoxidase activity, and lung bacterial load; intestinal epithelial barrier integrity was assessed by measuring blood-to-lumen clearance of Cr-EDTA; renal function was assessed by measuring plasma creatinine and urea; and myocardiac function was assessed using an isolated perfused mouse heart model. S. pneumoniae-induced pneumonia resulted in neutrophil infiltration into the lungs and increased lung bacterial load. Although relatively few bacteria gained access to the blood stream, the pneumonia was accompanied by increased intestinal epithelial barrier permeability, increased plasma creatinine, and decreased cardiac output and stroke volume. These data clearly show that intratracheal S. pneumoniae induced not only pneumonia but also MODS, despite the fact that few organisms gain access to the blood stream. This model can be used as a good gram-positive model of sepsis and MODS for further studies. PMID:18827750

Andonegui, Graciela; Goring, Kim; Liu, Dan; McCafferty, Donna-Marie; Winston, Brent W

2009-04-01

412

Isolation and identification of rumen bacteria capable of anaerobic phloroglucinol degradation.  

PubMed

Eight strains of rumen bacteria capable of degrading phloroglucinol (1,3,5-trihydroxybenzene) under anaerobic conditions were isolated from enrichment cultures of the bovine rumen microflora established in a prereduced medium containing 0.02 M phloroglucinol. Five of the strains were facultatively anaerobic Gram-positive streptococci which were identified as Streptococcus bovis. Three strains of obligately anaerobic Gram-positive cocci were assigned to the genus Coprococcus. Anaerobic cultures of the Streptococcus bovis strains in a 40% rumen fluid medium initially containing 0.02 M phloroglucinol degraded 50-80% of the substrate within 2 days, whereas cultures of the Coprococcus strains degraded more than 80% of the substrate under the same conditions. The Streptococcus bovis strains were incapable of degrading phloroglucinol in brain heart infusion or in the medium of de Man, Rogosa, and Sharpe (MRS broth) incubated aerobically. PMID:1170929

Tsai, C G; Jones, G A

1975-06-01

413

In Vitro Activities of Daptomycin, Vancomycin, Quinupristin- Dalfopristin, Linezolid, and Five Other Antimicrobials against 307 Gram-Positive Anaerobic and 31 Corynebacterium Clinical Isolates  

Microsoft Academic Search

The activities of daptomycin, a cyclic lipopeptide, and eight other agents were determined against 338 strains of gram-positive anaerobic bacteria and corynebacteria by the NCCLS reference agar dilution method with supplemen