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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

Sortase enzymes in Gram-positive bacteria  

PubMed Central

Summary In Gram-positive bacteria proteins are displayed on the cell surface using sortase enzymes. These cysteine transpeptidases join proteins bearing an appropriate sorting signal to strategically positioned amino groups on the cell surface. Working alone, or in concert with other enzymes, sortases either attach proteins to the cross-bridge peptide of the cell wall or they link proteins together to form pili. Because surface proteins play a fundamental role in microbial physiology and are frequently virulence factors, sortase enzymes have been intensely studied since their discovery a little more than a decade ago. Based on their primary sequences and functions sortases can be partitioned into distinct families called class A to F enzymes. Most bacteria elaborate their surfaces using more than one type of sortase that function non-redundantly by recognizing unique sorting signals within their protein substrates. Here we review what is known about the functions of these enzymes and the molecular basis of catalysis. Particular emphasis is placed on ‘pilin’ specific class C sortases that construct structurally complex pili. Exciting new data have revealed that these enzymes are amazingly promiscuous in the substrates that they can employ and that there is a startling degree of diversity in their mechanism of action. We also review recent data that suggest that sortases are targeted to specific sites on the cell surface where they work with other sortases and accessory factors to properly function. PMID:22026821

Spirig, Thomas; Weiner, Ethan M.; Clubb, Robert T.

2013-01-01

3

Screening genomes of Gram-positive bacteria for  

E-print Network

Screening genomes of Gram-positive bacteria for double-glycine-motif- containing peptides Secreted-positive bacteria, the double-glycine (GG) motif plays a key role in many peptide secretion systems involved Microbiology Comment #12;peptides and class II bacteriocins, produced by streptococci and lactic acid bacteria

4

Aerobic Respiration in the Gram-Positive Bacteria  

Microsoft Academic Search

The group of Gram-positive bacteria is a major phylum of prokaryotes, including several typical saprophytic aerobes. Their\\u000a respiratory chains are apparently similar to those of eukaryotic mitochondria, but in several points are different from them.\\u000a The respiratory chain of Gram-positives, like many bacteria, contains branched electron transfer pathways, usually 1-3 heme-Cu\\u000a oxidases, but SoxB-type cytochrome c oxidases (cytochrome b(a\\/o)3) are

Nobhuito Sone; Cecilia Hagerhall; Junshi Sakamoto

5

Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria  

PubMed Central

Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis.

McBride, Shonna M.

2014-01-01

6

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. PMID:22411983

Schneewind, Olaf; Missiakas, Dominique M.

2012-01-01

7

Wall Teichoic Acids of Gram-Positive Bacteria  

PubMed Central

The peptidoglycan layers of many gram-positive bacteria are densely functionalized with anionic glycopolymers called wall teichoic acids (WTAs). These polymers play crucial roles in cell shape determination, regulation of cell division, and other fundamental aspects of gram-positive bacterial physiology. Additionally, WTAs are important in pathogenesis and play key roles in antibiotic resistance. We provide an overview of WTA structure and biosynthesis, review recent studies on the biological roles of these polymers, and highlight remaining questions. We also discuss prospects for exploiting WTA biosynthesis as a target for new therapies to overcome resistant infections. PMID:24024634

Brown, Stephanie; Santa Maria, John P.; Walker, Suzanne

2013-01-01

8

Type IV Pili in Gram-Positive Bacteria  

PubMed Central

SUMMARY 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

Craig, Lisa

2013-01-01

9

Tandem affinity purification vectors for use in gram positive bacteria.  

PubMed

Tandem affinity purification has become a valuable tool for the isolation of protein complexes. Here we describe the construction and use of a series of plasmid vectors for Gram positive bacteria. The vectors utilize the SPA tag as well as variants containing a 3C rather than the TEV protease site as 3C protease has been shown to work efficiently at the low temperatures (4 degrees C) used to isolate protein complexes. In addition, a further vector incorporates a GST moiety in place of the 3xFLAG of the SPA tag which provides an additional tagging option for situations where SPA binding may be inefficient. The vectors are all compatible with previously constructed fluorescent protein fusion vectors enabling construction of a suite of affinity and fluorescently tagged genes using a single PCR product. PMID:18093654

Yang, Xiao; Doherty, Geoff P; Lewis, Peter J

2008-01-01

10

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

11

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. PMID:22913355

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

2012-01-01

12

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

Microsoft Academic Search

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

Peter Bruun Jordal; Morten Simonsen Dueholm; Poul Larsen; Steen Vang Petersen; Jan Johannes Enghild; Gunna Christiansen; P. Hojrup; Per Halkjær Nielsen; Daniel Erik Otzen

2009-01-01

13

Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria  

NASA Astrophysics Data System (ADS)

A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO2-NH2-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in the presence of anthracene-9,10-dipropionic acid. The capability of SiO2-NH2-RB nanoparticles to inactivate bacteria was tested in vitro on both gram-positive and gram-negative bacteria. The results showed that RB-decorated silica nanoparticles can inactivate MRSA and Staphylococcus epidermidis (both gram-positive) very effectively (up to eight-orders-of-magnitude reduction). Photosensitizers of such design should have good potential as antibacterial agents through a photodynamic mechanism.

Guo, Yanyan; Rogelj, Snezna; Zhang, Peng

2010-02-01

14

Small molecule inhibitor of lipoteichoic acid synthesis is an antibiotic for Gram-positive bacteria  

PubMed Central

The current epidemic of infections caused by antibiotic-resistant Gram-positive bacteria requires the discovery of new drug targets and the development of new therapeutics. Lipoteichoic acid (LTA), a cell wall polymer of Gram-positive bacteria, consists of 1,3-polyglycerol-phosphate linked to glycolipid. LTA synthase (LtaS) polymerizes polyglycerol-phosphate from phosphatidylglycerol, a reaction that is essential for the growth of Gram-positive bacteria. We screened small molecule libraries for compounds inhibiting growth of Staphylococcus aureus but not of Gram-negative bacteria. Compound 1771 [2-oxo-2-(5-phenyl-1,3,4-oxadiazol-2-ylamino)ethyl 2-naphtho[2,1-b]furan-1-ylacetate] blocked phosphatidylglycerol binding to LtaS and inhibited LTA synthesis in S. aureus and in Escherichia coli expressing ltaS. Compound 1771 inhibited the growth of antibiotic-resistant Gram-positive bacteria and prolonged the survival of mice with lethal S. aureus challenge, validating LtaS as a target for the development of antibiotics. PMID:23401520

Richter, Stefan G.; Elli, Derek; Kim, Hwan Keun; Hendrickx, Antoni P. A.; Sorg, Joseph A.; Schneewind, Olaf; Missiakas, Dominique

2013-01-01

15

Innate immune defense of the sponge Suberites domuncula against gram-positive bacteria: induction of lysozyme and AdaPTin  

Microsoft Academic Search

Sponges are filter feeders that are exposed to large amounts of bacteria present in their surrounding aqueous milieu. The characteristic cell wall component of gram-positive bacteria, peptidoglycan (PPG), was used as a model molecule to study the responsiveness of cells from the marine demosponge Suberites domuncula toward gram-positive bacteria. The sponge lysozyme, which hydrolyzes PPG, was isolated from the living

N. L. Thakur; S. Perovi?-Ottstadt; R. Batel; M. Korzhev; B. Diehl-Seifert; I. M. Müller; W. E. G. Müller

2005-01-01

16

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

17

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. PMID:15102780

Comfort, David; Clubb, Robert T.

2004-01-01

18

Novel antibiotics targeting respiratory ATP synthesis in Gram-positive pathogenic bacteria.  

PubMed

Emergence of drug-resistant bacteria represents a high, unmet medical need, and discovery of new antibacterials acting on new bacterial targets is strongly needed. ATP synthase has been validated as an antibacterial target in Mycobacterium tuberculosis, where its activity can be specifically blocked by the diarylquinoline TMC207. However, potency of TMC207 is restricted to mycobacteria with little or no effect on the growth of other Gram-positive or Gram-negative bacteria. Here, we identify diarylquinolines with activity against key Gram-positive pathogens, significantly extending the antibacterial spectrum of the diarylquinoline class of drugs. These compounds inhibited growth of Staphylococcus aureus in planktonic state as well as in metabolically resting bacteria grown in a biofilm culture. Furthermore, time-kill experiments showed that the selected hits are rapidly bactericidal. Drug-resistant mutations were mapped to the ATP synthase enzyme, and biochemical analysis as well as drug-target interaction studies reveal ATP synthase as a target for these compounds. Moreover, knockdown of the ATP synthase expression strongly suppressed growth of S. aureus, revealing a crucial role of this target in bacterial growth and metabolism. Our data represent a proof of principle for using the diarylquinoline class of antibacterials in key Gram-positive pathogens. Our results suggest that broadening the antibacterial spectrum for this chemical class is possible without drifting off from the target. Development of the diarylquinolines class may represent a promising strategy for combating Gram-positive pathogens. PMID:22615276

Balemans, Wendy; Vranckx, Luc; Lounis, Nacer; Pop, Ovidiu; Guillemont, Jérôme; Vergauwen, Karen; Mol, Selena; Gilissen, Ron; Motte, Magali; Lançois, David; De Bolle, Miguel; Bonroy, Kristien; Lill, Holger; Andries, Koen; Bald, Dirk; Koul, Anil

2012-08-01

19

Quorum sensing in gram-positive bacteria: assay protocols for staphylococcal agr and enterococcal fsr systems.  

PubMed

A thiolactone/lactone peptide-mediated quorum sensing (QS) system is commonly employed in gram-positive bacteria to control the expression of a variety of phenotypes, including the production of virulence factors and biofilm formation. Here, we describe assay protocols for the well-studied QS systems (agr and fsr) of two representative gram-positive pathogens, Staphylococcus aureus and Enterococcus faecalis. These convenient assay systems are useful for the screening of QS inhibitors as well as for basic research to address the mechanism of these QS systems. PMID:24664824

Shojima, Akane; Nakayama, Jiro

2014-01-01

20

Identification of Surprisingly Diverse Type IV Pili, across a Broad Range of Gram-Positive Bacteria  

PubMed Central

Background In Gram-negative bacteria, type IV pili (TFP) have long been known to play important roles in such diverse biological phenomena as surface adhesion, motility, and DNA transfer, with significant consequences for pathogenicity. More recently it became apparent that Gram-positive bacteria also express type IV pili; however, little is known about the diversity and abundance of these structures in Gram-positives. Computational tools for automated identification of type IV pilins are not currently available. Results To assess TFP diversity in Gram-positive bacteria and facilitate pilin identification, we compiled a comprehensive list of putative Gram-positive pilins encoded by operons containing highly conserved pilus biosynthetic genes (pilB, pilC). A surprisingly large number of species were found to contain multiple TFP operons (pil, com and/or tad). The N-terminal sequences of predicted pilins were exploited to develop PilFind, a rule-based algorithm for genome-wide identification of otherwise poorly conserved type IV pilins in any species, regardless of their association with TFP biosynthetic operons (http://signalfind.org). Using PilFind to scan 53 Gram-positive genomes (encoding >187,000 proteins), we identified 286 candidate pilins, including 214 in operons containing TFP biosynthetic genes (TBG+ operons). Although trained on Gram-positive pilins, PilFind identified 55 of 58 manually curated Gram-negative pilins in TBG+ operons, as well as 53 additional pilin candidates in operons lacking biosynthetic genes in ten species (>38,000 proteins), including 27 of 29 experimentally verified pilins. False positive rates appear to be low, as PilFind predicted only four pilin candidates in eleven bacterial species (>13,000 proteins) lacking TFP biosynthetic genes. Conclusions We have shown that Gram-positive bacteria contain a highly diverse set of type IV pili. PilFind can be an invaluable tool to study bacterial cellular processes known to involve type IV pilus-like structures. Its use in combination with other currently available computational tools should improve the accuracy of predicting the subcellular localization of bacterial proteins. PMID:22216142

Roos, David S.; Pohlschroder, Mechthild

2011-01-01

21

Protein transport across the cell wall of monoderm Gram-positive bacteria  

PubMed Central

Summary In monoderm (single membrane) Gram-positive bacteria, the majority of secreted proteins are first translocated across the cytoplasmic membrane into the inner wall zone. For a subset of these proteins, final destination is within the cell envelope either as membrane-anchored or cell wall-anchored proteins, whereas another subset of proteins is destined to be transported across the cell wall into the extracellular milieu. Although the cell wall is a porous structure, there is evidence that, for some proteins, transport is a regulated process. This review aims at describing what is known about the mechanisms that regulate the transport of proteins across the cell wall of monoderm Gram-positive bacteria. PMID:22471582

Forster, Brian M.; Marquis, Helene

2012-01-01

22

Synthetic Teichoic Acid Conjugate Vaccine against Nosocomial Gram-Positive Bacteria  

PubMed Central

Lipoteichoic acids (LTA) are amphiphilic polymers that are important constituents of the cell wall of many Gram-positive bacteria. The chemical structures of LTA vary among organisms, albeit in the majority of Gram-positive bacteria the LTAs feature a common poly-1,3-(glycerolphosphate) backbone. Previously, the specificity of opsonic antibodies for this backbone present in some Gram-positive bacteria has been demonstrated, suggesting that this minimal structure may be sufficient for vaccine development. In the present work, we studied a well-defined synthetic LTA-fragment, which is able to inhibit opsonic killing of polyclonal rabbit sera raised against native LTA from Enterococcus faecalis 12030. This promising compound was conjugated with BSA and used to raise rabbit polyclonal antibodies. Subsequently, the opsonic activity of this serum was tested in an opsonophagocytic assay and specificity was confirmed by an opsonophagocytic inhibition assay. The conjugated LTA-fragment was able to induce specific opsonic antibodies that mediate killing of the clinical strains E. faecalis 12030, Enterococcus faecium E1162, and community-acquired Staphylococcus aureus strain MW2 (USA400). Prophylactic immunization with the teichoic acid conjugate and with the rabbit serum raised against this compound was evaluated in active and passive immunization studies in mice, and in an enterococcal endocarditis rat model. In all animal models, a statistically significant reduction of colony counts was observed indicating that the novel synthetic LTA-fragment conjugate is a promising vaccine candidate for active or passive immunotherapy against E. faecalis and other Gram-positive bacteria. PMID:25333799

Laverde, Diana; Wobser, Dominique; Romero-Saavedra, Felipe; Hogendorf, Wouter; van der Marel, Gijsbert; Berthold, Martin; Kropec, Andrea; Codee, Jeroen; Huebner, Johannes

2014-01-01

23

Susceptibility of Gram-positive bacteria from ICU patients in UK hospitals to antimicrobial agents  

Microsoft Academic Search

Microbiologists in 25 sentinel laboratories were each asked to refer up to 100 clinically-significant Gram-positive bacteria isolated from consecutive intensive care unit (ICU) patients. A total of 1595 isolates were collected from patients in 23 hospitals; these included Staphylococcus aureus (47.6%), coagulase-negative staphylococci (CNS) (30.6%), enterococci (14.3%), pneumococci (2.8%) and other streptococci (3.5%). A few coryneforms, other bacilli and a

A. P Johnson; C Henwood; S Mushtaq; D James; M Warner; D. M Livermore

2003-01-01

24

Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria  

Microsoft Academic Search

A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO2-NH2-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in

Yanyan Guo; Snezna Rogelj; Peng Zhang

2010-01-01

25

Different subcellular locations of secretome components of Gram-positive bacteria  

Microsoft Academic Search

Gram-positive bacteria contain different types of secretion systems for the transport of proteins into or across the cytoplasmic membrane. Recent studies on subcellular localization of specific components of these secretion systems and their substrates have shown that they can be present at various locations in the cell. The translocons of the general Sec secretion system in the rod-shaped bacterium Bacillus

Girbe Buist; Anja N. J. A. Ridder; Jan Kok; Oscar P. Kuipers

2006-01-01

26

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. PMID:19395568

Jordal, Peter Bruun; Dueholm, Morten Simonsen; Larsen, Poul; Petersen, Steen Vang; Enghild, Jan Johannes; Christiansen, Gunna; Højrup, Peter; Nielsen, Per Halkjær; Otzen, Daniel Erik

2009-01-01

27

Rapid analysis of Gram-positive bacteria in water via membrane filtration coupled with nanoprobe-based MALDI-MS  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization (MALDI) mass spectrometry (MS) is challenging when it is directly applied to identify\\u000a bacteria in water. This study demonstrates a rapid, sensitive, and selective technique for detection of Gram-positive bacteria\\u000a in water. It involves a combination of membrane filtration (MF) and vancomycin-conjugated magnetite nanoparticles (VNPs) to\\u000a selectively separate and concentrate Gram-positive bacteria in tap water and reservoir

Shuping Li; Zhongxian Guo; Hui-Fen Wu; Ying Liu; Zhaoguang Yang; Chee Hoe Woo

2010-01-01

28

High benzene concentrations can favour Gram-positive bacteria in groundwaters from a contaminated aquifer.  

PubMed

Exposure to pollution exerts strong selective pressure on microbial communities, which may affect their potential to adapt to current or future environmental challenges. In this microcosm study, we used DNA fingerprinting based on 16S rRNA genes to document the impact of high concentrations of benzene on two bacterial communities from a benzene-contaminated aquifer situated below a petrochemical plant (SIReN, UK). The two groundwaters harboured distinct aerobic benzene-degrading communities able to metabolize benzene to below detection levels (1 microg L(-1)). A benzene concentration of 100 mg L(-1) caused a major shift from Betaproteobacteria to Actinobacteria, in particular Arthrobacter spp. A similar shift from Betaproteobacteria to Arthrobacter spp. and Rhodococcus erythropolis was observed in minimal medium (MM) inoculated with a third groundwater. These Gram-positive-dominated communities were able to grow on benzene at concentrations up to 600 mg L(-1) in groundwater and up to 1000 mg L(-1) in MM, concentrations that cause significant solvent stress to cellular systems. Therefore, Gram-positive bacteria were better competitors than Gram-negative organisms under experimental conditions of high benzene loads, which suggests that solvent-tolerant Gram-positive bacteria can play a role in the natural attenuation of benzene or the remediation of contaminated sites. PMID:18540887

Fahy, Anne; Ball, Andrew S; Lethbridge, Gordon; McGenity, Terry J; Timmis, Kenneth N

2008-09-01

29

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. PMID:17490609

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

30

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

31

Gram-positive marine bacteria as a potential resource for the discovery of quorum sensing inhibitors.  

PubMed

Inhibitors of bacterial quorum sensing have been proposed as potentially novel therapeutics for the treatment of certain bacterial diseases. We recently reported a marine Halobacillus salinus isolate that secretes secondary metabolites capable of quenching quorum sensing phenotypes in several Gram-negative reporter strains. To investigate how widespread the production of such compounds may be in the marine bacterial environment, 332 Gram-positive isolates from diverse habitats were tested for their ability to interfere with Vibrio harveyi bioluminescence, a cell signaling-regulated phenotype. Rapid assay methods were employed where environmental isolates were propagated alongside the reporter strain. "Actives" were defined as bacteria that interfered with bioluminescence without visible cell-killing effects (antibiotic activity). A total of 49 bacterial isolates interfered with bioluminescence production in the assays. Metabolite extracts were generated from cultures of the active isolates, and 28 reproduced the bioluminescence inhibition against V. harveyi. Of those 28, five extracts additionally inhibited violacein production by Chromobacterium violaceum. Chemical investigations revealed that phenethylamides and a cyclic dipeptide are two types of secondary metabolites responsible for the observed activities. The active bacterial isolates belonged primarily to either the genus Bacillus or Halobacillus. The results suggest that Gram-positive marine bacteria are worthy of further investigation for the discovery of quorum sensing antagonists. PMID:21152942

Teasdale, Margaret E; Donovan, Kellye A; Forschner-Dancause, Stephanie R; Rowley, David C

2011-08-01

32

Protein secretion biotechnology in Gram-positive bacteria with special emphasis on Streptomyces lividans.  

PubMed

Proteins secreted by Gram-positive bacteria are released into the culture medium with the obvious benefit that they usually retain their native conformation. This property makes these host cells potentially interesting for the production of recombinant proteins, as one can take full profit of established protocols for the purification of active proteins. Several state-of-the-art strategies to increase the yield of the secreted proteins will be discussed, using Streptomyces lividans as an example and compared with approaches used in some other host cells. It will be shown that approaches such as increasing expression and translation levels, choice of secretion pathway and modulation of proteins thereof, avoiding stress responses by changing expression levels of specific (stress) proteins, can be helpful to boost production yield. In addition, the potential of multi-omics approaches as a tool to understand the genetic background and metabolic fluxes in the host cell and to seek for new targets for strain and protein secretion improvement is discussed. It will be shown that S. lividans, along with other Gram-positive host cells, certainly plays a role as a production host for recombinant proteins in an economically viable way. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey. PMID:24412306

Anné, Jozef; Vrancken, Kristof; Van Mellaert, Lieve; Van Impe, Jan; Bernaerts, Kristel

2014-08-01

33

In Vitro Activities of RWJ-54428 (MC-02,479) against Multiresistant Gram-Positive Bacteria  

PubMed Central

RWJ-54428 (MC-02,479) is a new cephalosporin with a high level of activity against gram-positive bacteria. In a broth microdilution susceptibility test against methicillin-resistant Staphylococcus aureus (MRSA), RWJ-54428 was as active as vancomycin, with an MIC at which 90% of isolates are inhibited (MIC90) of 2 ?g/ml. For coagulase-negative staphylococci, RWJ-54428 was 32 times more active than imipenem, with an MIC90 of 2 ?g/ml. RWJ-54428 was active against S. aureus, Staphylococcus epidermidis, and Staphylococcus haemolyticus isolates with reduced susceptibility to glycopeptides (RWJ-54428 MIC range, ?0.0625 to 1 ?g/ml). RWJ-54428 was eight times more potent than methicillin and cefotaxime against methicillin-susceptible S. aureus (MIC90, 0.5 ?g/ml). For ampicillin-susceptible Enterococcus faecalis (including vancomycin-resistant and high-level aminoglycoside-resistant strains), RWJ-54428 had an MIC90 of 0.125 ?g/ml. RWJ-54428 was also active against Enterococcus faecium, including vancomycin-, gentamicin-, and ciprofloxacin-resistant strains. The potency against enterococci correlated with ampicillin susceptibility; RWJ-54428 MICs ranged between ?0.0625 and 1 ?g/ml for ampicillin-susceptible strains and 0.125 and 8 ?g/ml for ampicillin-resistant strains. RWJ-54428 was more active than penicillin G and cefotaxime against penicillin-resistant, -intermediate, and -susceptible strains of Streptococcus pneumoniae (MIC90s, 0.25, 0.125, and ?0.0625 ?g/ml, respectively). RWJ-54428 was only marginally active against most gram-negative bacteria; however, significant activity was observed against Haemophilus influenzae and Moraxella catarrhalis (MIC90s, 0.25 and 0.5 ?g/ml, respectively). This survey of the susceptibilities of more than 1,000 multidrug-resistant gram-positive isolates to RWJ-54428 indicates that this new cephalosporin has the potential to be useful in the treatment of infections due to gram-positive bacteria, including strains resistant to currently available antimicrobials. PMID:11302805

Chamberland, Suzanne; Blais, Johanne; Hoang, Monica; Dinh, Cynthia; Cotter, Dylan; Bond, Emmett; Gannon, Carla; Park, Craig; Malouin, Francois; Dudley, Michael N.

2001-01-01

34

[Retrospective analysis of the Gram-positive bacteria-infected cases in the Department of Hematology].  

PubMed

This study was purposed to evaluate the efficacy and safety of linezolid, vancomycin and teicoplanin for the treatment of patients infected by Gram-positive bacteria in the Department of Hematology by retrospective analysis. The patients with fever in our department from January to December in 2011 were selected for blood culture with Gram-positive bacteria and treated with linezolid, vancomycin or teicoplanin alone.Various parameters were recorded before and after treatment, such as fever time, respiratory symptoms, physical signs, radiographic changes, blood and biochemical routine, and adverse reactions. The efficacy and safety of linezolid, vancomycin and teicoplanin were compared according to the fever abating time, bacterial clearance rate, clinical efficiencies and adverse events. The patients were divided into linezolid group (15 patients), vancomycin group (17 patients) and teicoplanin group (20 patients). The results showed that the mean time of fever abating in linezolid group was (4.43 ± 3.15)d, bacterial clearance rate and clinical efficiency in linezolid group were 55.56% and 86.67%, respectively. The above three data in vancomycin group were (6.83 ± 4.67)d, 54.54% and 76.47% respectively, and were (5.57 ± 4.16)d, 41.67% and 80.00% in teicoplanin group respectively. There was no statistically significant difference between three groups (P > 0.05). There were one case of diarrhea and two cases of thrombocytopenia in the linezolid group, and one case of nausea and two cases of creatinine increase in the vancomycin group. There were three cases of thrombocytopenia in the teicoplanin group. The thrombocytopenia in five cases and the hemogram drop in patients with leukemia after treatment were overlapped, their drug treatment did not stop, but their thrombocytopoiesis recovered to normal-level, thus the drug treatment were considered as no relation with thrombocytopenia. It is concluded that the treatment efficacy between linezolid, vancomycin and teicoplanin for Gram-positive bacterial infections is not statistically different, but linezolid maybe have advantage over vancomycin and teicoplanin in fever abating time, bacterial clearance rate and clinical efficiency. PMID:24156452

Jing, Yu; Bo, Jian; Zhao, Yu; Li, Hong-Hua; Wang, Shu-Hong; Huang, Wen-Rong; Wang, Quan-Shun

2013-10-01

35

Genetic features of circular bacteriocins produced by Gram-positive bacteria.  

PubMed

This review highlights the main genetic features of circular bacteriocins, which require the co-ordinated expression of several genetic determinants. In general terms, it has been demonstrated that the expression of such structural genes must be combined with the activity of proteins involved in maturation (cleavage/circularization) and secretion outside the cell via different transporter systems, as well as multifaceted immunity mechanisms essential to ensuring the bacteria's self-protection against such strong inhibitors. Several circular antibacterial peptides produced by Gram-positive bacteria have been described to date, including enterocin AS-48, from Enterococcus faecalis S-48 (the first one characterized), gassericin A, from Lactobacillus gasseri LA39, and a similar one, reutericin 6, from Lactobacillus reuteri LA6, butyrivibriocin AR10, from the ruminal anaerobe Butyrivibrio fibrisolvens AR10, uberolysin, from Streptococcus uberis, circularin A, from Clostridium beijerinckii ATCC 25752, and subtilosin A, from Bacillus subtilis. We summarize here the progress made in the understanding of their principal genetic features over the last few years, during which the functional roles of circular proteins with wide biological activity have become clearer. PMID:18034824

Maqueda, Mercedes; Sánchez-Hidalgo, Marina; Fernández, Matilde; Montalbán-López, Manuel; Valdivia, Eva; Martínez-Bueno, Manuel

2008-01-01

36

Raman Spectroscopy of Xylitol Uptake and Metabolism in Gram-Positive and Gram-Negative Bacteria?  

PubMed Central

Visible-wavelength Raman spectroscopy was used to investigate the uptake and metabolism of the five-carbon sugar alcohol xylitol by Gram-positive viridans group streptococcus and the two extensively used strains of Gram-negative Escherichia coli, E. coli C and E. coli K-12. E. coli C, but not E. coli K-12, contains a complete xylitol operon, and the viridans group streptococcus contains an incomplete xylitol operon used to metabolize the xylitol. Raman spectra from xylitol-exposed viridans group streptococcus exhibited significant changes that persisted even in progeny grown from the xylitol-exposed mother cells in a xylitol-free medium for 24 h. This behavior was not observed in the E. coli K-12. In both viridans group streptococcus and the E. coli C derivative HF4714, the metabolic intermediates are stably formed to create an anomaly in bacterial normal survival. The uptake of xylitol by Gram-positive and Gram-negative pathogens occurs even in the presence of other high-calorie sugars, and its stable integration within the bacterial cell wall may discontinue bacterial multiplication. This could be a contributing factor for the known efficacy of xylitol when taken as a prophylactic measure to prevent or reduce occurrences of persistent infection. Specifically, these bacteria are causative agents for several important diseases of children such as pneumonia, otitis media, meningitis, and dental caries. If properly explored, such an inexpensive and harmless sugar-alcohol, alone or used in conjunction with fluoride, would pave the way to an alternative preventive therapy for these childhood diseases when the causative pathogens have become resistant to modern medicines such as antibiotics and vaccine immunotherapy. PMID:21037297

Palchaudhuri, Sunil; Rehse, Steven J.; Hamasha, Khozima; Syed, Talha; Kurtovic, Eldar; Kurtovic, Emir; Stenger, James

2011-01-01

37

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

38

[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

39

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

PubMed Central

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

2013-01-01

40

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

41

Distribution of multi-resistant Gram-negative versus Gram-positive bacteria in the hospital inanimate environment  

Microsoft Academic Search

We prospectively studied the difference in detection rates of multi-resistant Gram-positive and multi-resistant Gram-negative bacteria in the inanimate environment of patients harbouring these organisms. Up to 20 different locations around 190 patients were surveyed. Fifty-four patients were infected or colonized with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE) and 136 with multi-resistant Gram-negative bacteria. The environmental detection rate for

S. W Lemmen; H Häfner; D Zolldann; S Stanzel; R Lütticken

2004-01-01

42

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

43

Relevance of GC content to the conservation of DNA polymerase III/mismatch repair system in Gram-positive bacteria  

PubMed Central

The mechanism of DNA replication is one of the driving forces of genome evolution. Bacterial DNA polymerase III, the primary complex of DNA replication, consists of PolC and DnaE. PolC is conserved in Gram-positive bacteria, especially in the Firmicutes with low GC content, whereas DnaE is widely conserved in most Gram-negative and Gram-positive bacteria. PolC contains two domains, the 3?-5?exonuclease domain and the polymerase domain, while DnaE only possesses the polymerase domain. Accordingly, DnaE does not have the proofreading function; in Escherichia coli, another enzyme DnaQ performs this function. In most bacteria, the fidelity of DNA replication is maintained by 3?-5? exonuclease and a mismatch repair (MMR) system. However, we found that most Actinobacteria (a group of Gram-positive bacteria with high GC content) appear to have lost the MMR system and chromosomes may be replicated by DnaE-type DNA polymerase III with DnaQ-like 3?-5? exonuclease. We tested the mutation bias of Bacillus subtilis, which belongs to the Firmicutes and found that the wild type strain is AT-biased while the mutS-deletant strain is remarkably GC-biased. If we presume that DnaE tends to make mistakes that increase GC content, these results can be explained by the mutS deletion (i.e., deletion of the MMR system). Thus, we propose that GC content is regulated by DNA polymerase and MMR system, and the absence of polC genes, which participate in the MMR system, may be the reason for the increase of GC content in Gram-positive bacteria such as Actinobacteria. PMID:24062730

Akashi, Motohiro; Yoshikawa, Hirofumi

2013-01-01

44

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. PMID:24223039

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

2013-01-01

45

Amplifiable DNA from Gram-negative and Gram-positive bacteria by a low strength pulsed electric field method  

Microsoft Academic Search

An efficient electric field-based procedure for cell disruption and DNA isolation is described. Isoosmotic suspensions of Gram-negative and Gram-positive bacteria were treated with pulsed electric fields of <60 V\\/cm. Pulses had an exponential decay waveform with a time constant of 3.4 µs. DNA yield was linearly dependent on time or pulse number, with several thousand pulses needed. Electrochemical side-effects and

Frank Vitzthum; Georg Geiger; Hans Bisswanger; Bentsian Elkine; Herwig Brunner; Jürgen Bernhagen

2000-01-01

46

Comparative in vitro activities of L-695,256, a novel carbapenem, against gram-positive bacteria.  

PubMed Central

The in vitro activity of a prototype 2-aryl carbapenem, L-695,256, against gram-positive bacteria was examined. All streptococci and oxacillin-susceptible and -resistant staphylococci were inhibited at concentrations of < or = 0.125, < or = 0.125, and 4 micrograms/ml, respectively. The activity of L-695,256 was superior to that of imipenem against other organisms intrinsically resistant to beta-lactams. PMID:7786011

Malanoski, G; Collins, L; Eliopoulos, C T; Moellering, R C; Eliopoulos, G M

1995-01-01

47

A novel beta-defensin structure: a potential strategy of big defensin for overcoming resistance by Gram-positive bacteria.  

PubMed

Big defensin is a 79-residue peptide derived from hemocytes of the Japanese horseshoe crab. It has antimicrobial activities against Gram-positive and -negative bacteria. The amino acid sequence of big defensin can be divided into an N-terminal hydrophobic half and a C-terminal cationic half. Interestingly, the trypsin cleaves big defensin into two fragments, the N-terminal and C-terminal fragments, which are responsible for antimicrobial activity against Gram-positive and -negative bacteria, respectively. To explore the antimicrobial mechanism of big defensin, we determined the solution structure of mature big defensin and performed a titration experiment with DPC micelles. Big defensin has a novel defensin structure; the C-terminal domain adopts a beta-defensin structure, and the N-terminal domain forms a unique globular conformation. It is noteworthy that the hydrophobic N-terminal domain undergoes a conformational change in micelle solution, while the C-terminal domain remains unchanged. Here, we propose that the N-terminal domain achieves its antimicrobial activity in a novel fashion and explain that big defensin has developed a strategy different from those of other beta-defensins to suppress the growth of Gram-positive bacteria. PMID:18785751

Kouno, Takahide; Fujitani, Naoki; Mizuguchi, Mineyuki; Osaki, Tsukasa; Nishimura, Shin-ichiro; Kawabata, Shun-ichiro; Aizawa, Tomoyasu; Demura, Makoto; Nitta, Katsutoshi; Kawano, Keiichi

2008-10-01

48

Phylogenetic diversity of gram-positive bacteria and their secondary metabolite genes  

E-print Network

bacteria continue to be the focus of chemical investigations and with the possibility of representing a new genus, identifyingbacteria continue to be the focus of chemical investigations and with the possibility of representing a new genus, identifying

Gontang, Erin Ann

2008-01-01

49

Phylogenetic Diversity of Gram-positive Bacteria and Their Secondary Metabolite Genes  

E-print Network

bacteria continue to be the focus of chemical investigations and with the possibility of representing a new genus, identifyingbacteria continue to be the focus of chemical investigations and with the possibility of representing a new genus, identifying

Gontang, Erin A

2008-01-01

50

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. PMID:23233805

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

2012-01-01

51

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

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

2014-05-01

52

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

53

Acyl-sulfamates target the essential glycerol-phosphate acyltransferase (PlsY) in Gram-positive bacteria.  

PubMed

PlsY is the essential first step in membrane phospholipid synthesis of Gram-positive pathogens. PlsY catalyzes the transfer of the fatty acid from acyl-phosphate to the 1-position of glycerol-3-phosphate to form the first intermediate in membrane biogenesis. A series of non-metabolizable, acyl-sulfamate analogs of the acyl-phosphate PlsY substrate were prepared and evaluated as inhibitors of Staphylococcus aureus PlsY and for their Gram-positive antibacterial activities. From this series phenyl (8-phenyloctanoyl) sulfamate had the best overall profile, selectively inhibiting S. aureus phospholipid biosynthesis and causing the accumulation of both long-chain fatty acids and acyl-acyl carrier protein intermediates demonstrating that PlsY was the primary cellular target. Bacillus anthracis was unique in being more potently inhibited by long chain acyl-sulfamates than other bacterial species. However, it is shown that Bacillus anthracis PlsY is not more sensitive to the acyl-sulfamates than S. aureus PlsY. Metabolic profiling showed that B. anthracis growth inhibition by the acyl-sulfamates was not specific for lipid synthesis illustrating that the amphipathic acyl-sulfamates can also have off-target effects in Gram-positive bacteria. Nonetheless, this study further advances PlsY as a druggable target for the development of novel antibacterial therapeutics, through the discovery and validation of the probe compound phenyl (8-phenyloctanoyl) sulfamate as a S. aureus PlsY inhibitor. PMID:22795901

Cherian, Philip T; Yao, Jiangwei; Leonardi, Roberta; Maddox, Marcus M; Luna, Vicki A; Rock, Charles O; Lee, Richard E

2012-08-15

54

Acyl-sulfamates Target the Essential Glycerol-Phosphate Acyltransferase (PlsY) in Gram-Positive Bacteria  

PubMed Central

PlsY is the essential first step in membrane phospholipid synthesis of Gram-positive pathogens. PlsY catalyzes the transfer of the fatty acid from acyl-phosphate to the 1-position of glycerol-3-phosphate to form the first intermediate in membrane biogenesis. A series of non-metabolizable, acyl-sulfamate analogs of the acyl-phosphate PlsY substrate were prepared and evaluated as inhibitors of Staphylococcus aureus PlsY and for their Gram-positive antibacterial activities. From this series phenyl (8-phenyloctanoyl) sulfamate had the best overall profile, selectively inhibiting S. aureus phospholipid biosynthesis and causing the accumulation of both long-chain fatty acids and acyl-acyl carrier protein intermediates demonstrating that PlsY was the primary cellular target. Bacillus anthracis was unique in being more potently inhibited by long chain acyl-sulfamates than other bacterial species. However, it is shown that Bacillus anthracis PlsY is not more sensitive to the acyl-sulfamates than S. aureus PlsY. Metabolic profiling showed that B. anthracis growth inhibition by the acyl-sulfamates was not specific for lipid synthesis illustrating that the amphipathic acyl-sulfamates can also have off-target effects in Gram-positive bacteria. Nonetheless, this study further advances PlsY as a druggable target for the development of novel antibacterial therapeutics, through the discovery and validation of the probe compound phenyl (8-phenyloctanoyl) sulfamate as a S. aureus PlsY inhibitor. PMID:22795901

Cherian, Philip; Yao, Jiangwei; Leonardi, Roberta; Maddox, Marcus M.; Luna, Vicki A.; Rock, Charles O.; Lee, Richard E.

2012-01-01

55

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

56

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

PubMed Central

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 1 integrons in poultry litter is not their previously identified hosts, Gram-negative Enterobacteriaceae such as Escherichia coli. Rather, integrons and associated resistance genes abound in several genera of Gram-positive bacteria that constitute >85% of the litter community compared with Enterobacteriaceae that comprise <2% of this ecosystem. This finding warrants reexamination of our assumptions about the persistence and spread of antibiotic resistance genes. PMID:15107498

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

2004-01-01

57

Evidence for high affinity binding-protein dependent transport systems in gram-positive bacteria and in Mycoplasma.  

PubMed Central

Gram-negative bacteria are surrounded by two membranes. In these bacteria, a class of high affinity transport systems for concentrating substrates from the medium into the cell, involves a binding protein located between the outer and inner membranes, in the periplasmic region. These 'periplasmic binding-proteins' are thought to bind the substrate in the vicinity of the inner membrane, and to transfer it to a complex of inner membrane proteins for concentration into the cytoplasm. We report evidence leading us to propose that a Gram-positive bacterium, Streptococcus pneumoniae, and a mycoplasma, Mycoplasma hyorhinis, which are surrounded by a single membrane and have therefore no periplasmic region, possess an equivalent to the high affinity periplasmic binding-protein dependent transport systems, i.e. extra-cytoplasmic binding lipoprotein dependent transport systems. The 'binding lipoproteins' would be maintained at proximity of the inner membrane by insertion of their N-terminal glyceride-cysteine into this membrane. Images PMID:3208757

Gilson, E; Alloing, G; Schmidt, T; Claverys, J P; Dudler, R; Hofnung, M

1988-01-01

58

Selective adsorption of heterophile polyglycerophosphate antigen from antigen extracts of Streptococcus mutans and other gram-positive bacteria.  

PubMed Central

Hot saline extracts of Streptococcus mutans have been shown to contain antigenic substances which occasionally react nonspecifically with some antisera against whole cells of various serological groups and types of streptococci. Chromatography of the extract of S. mutans strain MT703 (serotype e) on a diethylaminoethyl-Sephadex A-25 column gave two principal antigens. One antigen was eluted without adsorption to the resin and was identified as the serotype-specific polysaccharide. The other antigen, which contained a large quantity of phosphorus, was absorbed to and released from the resin by gradient elution. It was reactive against the antisera specific for polyglycerophosphate (PGP) from group A Streptococcus pyogenes and/or S. mutans strain Ingbritt (type c). The PGP antigen was further purified by gel filtration with Sephadex G-75. Two peaks, PGP-1, and PGP-2, were obtained. Each possessed the same antigenic specificity to anti-PGP serum as shown by immunodiffusion. Chemical analyses revealed that the molar ratio of phosphorus to glycerol in both was about 1:1, although the protein content between the two was significantly different. PGP antigen was found to be widely distributed in hot saline extracts from various gram-positive bacteria, with a few exceptions. However, all gram-negative bacteria examined were free of PGP. The PGP in the hot saline extracts of various gram-positive bacteria possessed an essentially identical antigenic specificity. The addition of diethylaminoethyl-Sephadex A-25 resin to hot saline extracts successfully removed the cross-reacting PGP antigen. After adsorption of the extract from S. mutans, the supernatant contained only type-specific polysaccharide antigen, except type b, in which both type b-specific polysaccharide and PGP antigens were absorbed with the resin. This simple procedure should be useful for the removal of the PGP-type teichoic acid from antigen extracts of bacteria that contain uncharged polysaccharides. Images PMID:825468

Hamada, S; Tai, S; Slade, H D

1976-01-01

59

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. PMID:23771138

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

60

Performances of VITEK 2 Colorimetric Cards for Identification of Gram-Positive and Gram-Negative Bacteria  

PubMed Central

Thepurpose of this study was to evaluate the new VITEK 2 identification cards that use colorimetric reading to identify gram-positive and gram-negative bacteria (GP and GN cards, respectively) in comparison to fluorimetric cards (ID-GPC and ID-GNB, respectively). A total of 580 clinical isolates and stock collection strains belonging to 116 taxa were included in the study. Of the 249 gram-positive strains tested with both the ID-GPC and GP cards, 218 (87.5%) and 235 (94.4%) strains were correctly identified (to the genus and species level), respectively. Of the 331 gram-negative strains tested with the ID-GNB and GN cards, 295 (89.1%) and 321 (97%) strains were correctly identified, respectively. Another focus of the study was to apply the percentages of correct identifications obtained in this study to the list of bacteria isolated in our laboratory (32,739 isolates) in the year 2004. We obtained 97.9% correct identifications with the colorimetric cards and 93.9% with fluorescent cards. PMID:16145083

Wallet, Frederic; Loiez, Caroline; Renaux, Emilie; Lemaitre, Nadine; Courcol, Rene J.

2005-01-01

61

Surface Proteins of Gram-Positive Bacteria and Mechanisms of Their Targeting to the Cell Wall Envelope  

PubMed Central

The cell wall envelope of gram-positive bacteria is a macromolecular, exoskeletal organelle that is assembled and turned over at designated sites. The cell wall also functions as a surface organelle that allows gram-positive pathogens to interact with their environment, in particular the tissues of the infected host. All of these functions require that surface proteins and enzymes be properly targeted to the cell wall envelope. Two basic mechanisms, cell wall sorting and targeting, have been identified. Cell well sorting is the covalent attachment of surface proteins to the peptidoglycan via a C-terminal sorting signal that contains a consensus LPXTG sequence. More than 100 proteins that possess cell wall-sorting signals, including the M proteins of Streptococcus pyogenes, protein A of Staphylococcus aureus, and several internalins of Listeria monocytogenes, have been identified. Cell wall targeting involves the noncovalent attachment of proteins to the cell surface via specialized binding domains. Several of these wall-binding domains appear to interact with secondary wall polymers that are associated with the peptidoglycan, for example teichoic acids and polysaccharides. Proteins that are targeted to the cell surface include muralytic enzymes such as autolysins, lysostaphin, and phage lytic enzymes. Other examples for targeted proteins are the surface S-layer proteins of bacilli and clostridia, as well as virulence factors required for the pathogenesis of L. monocytogenes (internalin B) and Streptococcus pneumoniae (PspA) infections. In this review we describe the mechanisms for both sorting and targeting of proteins to the envelope of gram-positive bacteria and review the functions of known surface proteins. PMID:10066836

Navarre, William Wiley; Schneewind, Olaf

1999-01-01

62

Mechanism of Action of Recombinant Acc-Royalisin from Royal Jelly of Asian Honeybee against Gram-Positive Bacteria  

PubMed Central

The antibacterial activity of royalisin, an antimicrobial peptide from the royal jelly produced by honeybees, has been addressed extensively. However, its mechanism of action remains unclear. In this study, a recombinant royalisin, RAcc-royalisin from the royal jelly of Asian honeybee Apis cerana cerana, was expressed by fusing with glutathione S-transferase (GST) in Escherichia coli BL21, isolated and purified. The agar dilution assays with inhibition zone showed that RAcc-royalisin, similar to nisin, inhibits the growth of Gram-positive bacteria. The antibacterial activity of RAcc-royalisin was associated with its concentration, and was weakened by heat treatment ranging from 55°C to 85°C for 15 min. Both RAcc-royalisin and nisin exhibited the minimum inhibitory concentrations (MIC) of 62.5 µg/ml, 125 µg/ml, and 250 µg/ml against Gram-positive bacterial strains, Bacillus subtilis and Micrococcus flavus and Staphyloccocus aureus in the microplate assay, respectively. However, RAcc-royalisin did not show antimicrobial activity against tested Gram-negative bacterial and fungal strains. The antibacterial activity of RAcc-royalisin agrees well with the decrease in bacterial cell hydrophobicity, the leakage of 260-nm absorbing materials, and the observation by transmission electron microscopy, all indicating that RAcc-royalisin induced the disruption and dysfunction of cell walls and membranes. This is the first report detailing the antibacterial mechanism of royalisin against Gram-positive bacteria, and provides insight into the application of recombinant royalisin in food and pharmaceutical industries as an antimicrobial agent. PMID:23056609

Shen, Lirong; Liu, Dandan; Li, Meilu; Jin, Feng; Din, Meihui; Parnell, Laurence D.; Lai, Chao-Qiang

2012-01-01

63

Surface roughness mediated adhesion forces between borosilicate glass and gram-positive bacteria.  

PubMed

It is well-known that a number of surface characteristics affect the extent of adhesion between two adjacent materials. One of such parameters is the surface roughness as surface asperities at the nanoscale level govern the overall adhesive forces. For example, the extent of bacterial adhesion is determined by the surface topography; also, once a bacteria colonizes a surface, proliferation of that species will take place and a biofilm may form, increasing the resistance of bacterial cells to removal. In this study, borosilicate glass was employed with varying surface roughness and coated with bovine serum albumin (BSA) in order to replicate the protein layer that covers orthopedic devices on implantation. As roughness is a scale-dependent process, relevant scan areas were analyzed using atomic force microscope (AFM) to determine Ra; furthermore, appropriate bacterial species were attached to the tip to measure the adhesion forces between cells and substrates. The bacterial species chosen (Staphylococci and Streptococci) are common pathogens associated with a number of implant related infections that are detrimental to the biomedical devices and patients. Correlation between adhesion forces and surface roughness (Ra) was generally better when the surface roughness was measured through scanned areas with size (2 × 2 ?m) comparable to bacteria cells. Furthermore, the BSA coating altered the surface roughness without correlation with the initial values of such parameter; therefore, better correlations were found between adhesion forces and BSA-coated surfaces when actual surface roughness was used instead of the initial (nominal) values. It was also found that BSA induced a more hydrophilic and electron donor characteristic to the surfaces; in agreement with increasing adhesion forces of hydrophilic bacteria (as determined through microbial adhesion to solvents test) on BSA-coated substrates. PMID:25019516

Preedy, Emily; Perni, Stefano; Nipi?, Damijan; Bohinc, Klemen; Prokopovich, Polina

2014-08-12

64

In Vitro Activity of Telavancin against Resistant Gram-Positive Bacteria?  

PubMed Central

The in vitro activity of telavancin was tested against 743 predominantly antimicrobial-resistant, gram-positive isolates. Telavancin was highly active against methicillin-resistant staphylococci (MIC90, 0.5 to 1 ?g/ml), streptococci (all MICs, ?0.12 ?g/ml), and VanB-type enterococci (all MICs, ?2 ?g/ml). Time-kill studies demonstrated the potent bactericidal activity of telavancin. PMID:18443122

Krause, Kevin M.; Renelli, Marika; Difuntorum, Stacey; Wu, Terry X.; Debabov, Dmitri V.; Benton, Bret M.

2008-01-01

65

Gram-Positive Marine Bacteria as a Potential Resource for the Discovery of Quorum Sensing Inhibitors  

Microsoft Academic Search

Inhibitors of bacterial quorum sensing have been proposed as potentially novel therapeutics for the treatment of certain bacterial\\u000a diseases. We recently reported a marine Halobacillus salinus isolate that secretes secondary metabolites capable of quenching quorum sensing phenotypes in several Gram-negative reporter\\u000a strains. To investigate how widespread the production of such compounds may be in the marine bacterial environment, 332 Gram-positive

Margaret E. Teasdale; Kellye A. Donovan; Stephanie R. Forschner-Dancause; David C. Rowley

66

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. PMID:24348471

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

2013-01-01

67

Amplifiable DNA from gram-negative and gram-positive bacteria by a low strength pulsed electric field method.  

PubMed

An efficient electric field-based procedure for cell disruption and DNA isolation is described. Isoosmotic suspensions of Gram-negative and Gram-positive bacteria were treated with pulsed electric fields of <60 V/cm. Pulses had an exponential decay waveform with a time constant of 3.4 micros. DNA yield was linearly dependent on time or pulse number, with several thousand pulses needed. Electrochemical side-effects and electrophoresis were minimal. The lysates contained non-fragmented DNA which was readily amplifiable by PCR. As the method was not limited to samples of high specific resistance, it should be applicable to physiological fluids and be useful for genomic and DNA diagnostic applications. PMID:10734214

Vitzthum, F; Geiger, G; Bisswanger, H; Elkine, B; Brunner, H; Bernhagen, J

2000-04-15

68

Multistep Resistance Development Studies of Ceftaroline in Gram-Positive and -Negative Bacteria?  

PubMed Central

Ceftaroline, the active component of the prodrug ceftaroline fosamil, is a novel broad-spectrum cephalosporin with bactericidal activity against Gram-positive and -negative isolates. This study evaluated the potential for ceftaroline and comparator antibiotics to select for clones of Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis with elevated MICs. S. pneumoniae and S. pyogenes isolates in the present study were highly susceptible to ceftaroline (MIC range, 0.004 to 0.25 ?g/ml). No streptococcal strains yielded ceftaroline clones with increased MICs (defined as an increase in MIC of >4-fold) after 50 daily passages. Ceftaroline MICs for H. influenzae and M. catarrhalis were 0.06 to 2 ?g/ml for four strains and 8 ?g/ml for a ?-lactamase-positive, efflux-positive H. influenzae with a mutation in L22. One H. influenzae clone with an increased ceftaroline MIC (quinolone-resistant, ?-lactamase-positive) was recovered after 20 days. The ceftaroline MIC for this isolate increased 16-fold, from 0.06 to 1 ?g/ml. MICs for S. aureus ranged from 0.25 to 1 ?g/ml. No S. aureus isolates tested with ceftaroline had clones with increased MIC (>4-fold) after 50 passages. Two E. faecalis isolates tested had ceftaroline MICs increased from 1 to 8 ?g/ml after 38 days and from 4 to 32 ?g/ml after 41 days, respectively. The parental ceftaroline MIC for the one K. pneumoniae extended-spectrum ?-lactamase-negative isolate tested was 0.5 ?g/ml and did not change after 50 daily passages. PMID:21343467

Clark, Catherine; McGhee, Pamela; Appelbaum, Peter C.; Kosowska-Shick, Klaudia

2011-01-01

69

Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria  

NASA Astrophysics Data System (ADS)

Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases.

Gurunathan, Sangiliyandi; Han, Jae Woong; Kwon, Deug-Nam; Kim, Jin-Hoi

2014-07-01

70

Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria  

PubMed Central

Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases. PMID:25136281

2014-01-01

71

Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria.  

PubMed

Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases. PMID:25136281

Gurunathan, Sangiliyandi; Han, Jae Woong; Kwon, Deug-Nam; Kim, Jin-Hoi

2014-01-01

72

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

73

Type I and Type II mechanisms of antimicrobial photodynamic therapy: An in vitro study on Gram-negative and Gram-positive bacteria  

PubMed Central

Background and Objectives Antimicrobial photodynamic therapy (APDT) employs a nontoxic photosensitizer (PS) and visible light, which in the presence of oxygen produce reactive oxygen species (ROS), such as singlet oxygen (1O2, produced via Type II mechanism) and hydroxyl radical (HO•, produced via Type I mechanism). This study examined the relative contributions of 1O2 and HO• to APDT killing of Gram-positive and Gram-negative bacteria. Study Design/Materials and Methods Fluorescence probes, 3'-(p-hydroxyphenyl)-fluorescein (HPF) and singlet oxygen sensor green reagent (SOSG) were used to determine HO• and 1O2 produced by illumination of two PS: tris-cationic-buckminsterfullerene (BB6) and a conjugate between polyethylenimine and chlorin(e6) (PEI–ce6). Dimethylthiourea is a HO• scavenger, while sodium azide (NaN3) is a quencher of 1O2. Both APDT and killing by Fenton reaction (chemical generation of HO•) were carried out on Gram-positive bacteria (Staphylococcus aureus and Enteroccoccus fecalis) and Gram-negative bacteria (Escherichia coli, Proteus mirabilis and Pseudomonas aeruginosa. Results Conjugate PEI-ce6 mainly produced 1O2 (quenched by NaN3), while BB6 produced HO• in addition to 1O2 when NaN3 potentiated probe activation. NaN3 also potentiated HPF activation by Fenton reagent. All bacteria were killed by Fenton reagent but Gram-positive bacteria needed a higher concentration than Gram-negatives. NaN3 potentiated Fenton-mediated killing of all bacteria. The ratio of APDT killing between Gram-positive and Gram-negative bacteria was 2 or 4:1 for BB6 and 25:1 for conjugate PEI-ce6. There was a NaN3 dose dependent inhibition of APDT killing using both PEI-ce6 and BB6 against Gram-negative bacteria while NaN3 almost failed to inhibit killing of Gram-positive bacteria. Conclusion Azidyl radicals may be formed from NaN3 and HO•. It may be that Gram-negative bacteria are more susceptible to HO• while Gram-positive bacteria are more susceptible to 1O2. The differences in NaN3 inhibition may reflect differences in the extent of PS binding to bacteria (microenvironment) or differences in penetration of NaN3 into cell walls of bacteria. PMID:22760848

Huang, Liyi; Xuan, Yi; Koide, Yuichiro; Zhiyentayev, Timur; Tanaka, Masamitsu; Hamblin, Michael R.

2012-01-01

74

Silver-doped manganese dioxide and trioxide nanoparticles inhibit both gram positive and gram negative pathogenic bacteria.  

PubMed

Palladium, ruthenium and silver-doped MnO2 and silver doped Mn2O3 nanoparticles were synthesized by simple co-precipitation technique. SEM-TEM analysis revealed the nano-size of these synthesized samples. XPS data illustrates that Mn is present in 4+ and 3+ oxidation states in MnO2 and Mn2O3 respectively. Thermal analysis gave significant evidence for the phase changes with increasing temperature. Antibacterial activity of these synthesized nanoparticles on three Gram positive bacterial cultures (Staphylococcus aureus ATCC 6538, Streptococcus epidermis ATCC 12228, Bacillus subtilis ATCC 6633) and three Gram negative cultures (Escherichia coli ATCC 8739, Salmonella abony NCTC 6017 and Klebsiella pneumoniae ATCC 1003) was investigated using a disc diffusion method and live/dead assay. Only Ag-doped MnO2 and Ag-doped Mn2O3 nanoparticles showed antibacterial property against all six-test bacteria but Ag-doped MnO2 was found to be more effective than Ag-doped Mn2O3. PMID:24140741

Kunkalekar, R K; Prabhu, M S; Naik, M M; Salker, A V

2014-01-01

75

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. PMID:23077549

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

2012-01-01

76

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

77

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. PMID:22303020

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

78

The PECACE domain: a new family of enzymes with potential peptidoglycan cleavage activity in Gram-positive bacteria  

PubMed Central

Background The metabolism of bacterial peptidoglycan is a dynamic process, synthases and cleavage enzymes are functionally coordinated. Lytic Transglycosylase enzymes (LT) are part of multienzyme complexes which regulate bacterial division and elongation. LTs are also involved in peptidoglycan turnover and in macromolecular transport systems. Despite their central importance, no LTs have been identified in the human pathogen Streptococcus pneumoniae. We report the identification of the first putative LT enzyme in S. pneumoniae and discuss its role in pneumococcal peptidoglycan metabolism. Results Homology searches of the pneumococcal genome allowed the identification of a new domain putatively involved in peptidoglycan cleavage (PECACE, PEptidoglycan CArbohydrate Cleavage Enzyme). This sequence has been found exclusively in Gram-positive bacteria and gene clusters containing pecace are conserved among Streptococcal species. The PECACE domain is, in some instances, found in association with other domains known to catalyze peptidoglycan hydrolysis. Conclusions A new domain, PECACE, putatively involved in peptidoglycan hydrolysis has been identified in S. pneumoniae. The probable enzymatic activity deduced from the detailed analysis of the amino acid sequence suggests that the PECACE domain may proceed through a LT-type or goose lyzosyme-type cleavage mechanism. The PECACE function may differ largely from the other hydrolases already identified in the pneumococcus: LytA, LytB, LytC, CBPD and PcsB. The multimodular architecture of proteins containing the PECACE domain is another example of the many activities harbored by peptidoglycan hydrolases, which is probably required for the regulation of peptidoglycan metabolism. The release of new bacterial genomes sequences will probably add new members to the five groups identified so far in this work, and new groups could also emerge. Conversely, the functional characterization of the unknown domains mentioned in this work can now become easier, since bacterial peptidoglycan is proposed to be the substrate. PMID:15717932

Pagliero, Estelle; Dideberg, Otto; Vernet, Thierry; Di Guilmi, Anne Marie

2005-01-01

79

Efficient enzymatic systems for synthesis of novel ?-mangostin glycosides exhibiting antibacterial activity against Gram-positive bacteria.  

PubMed

Two enzymatic systems were developed for the efficient synthesis of glycoside products of ?-mangostin, a natural xanthonoid exhibiting anti-oxidant, antibacterial, anti-inflammatory, and anticancer activities. In these systems, one-pot reactions for the synthesis of UDP-?-D-glucose and UDP-?-D-2-deoxyglucose were modified and combined with a glycosyltransferase (GT) from Bacillus licheniformis DSM-13 to afford C-3 and C-6 position modified glucose and 2-deoxyglucose conjugated novel ?-mangostin derivatives. ?-Mangostin 3-O-?-D-glucopyranoside, ?-mangostin 6-O-?-D-glucopyranoside, ?-mangostin 3,6-di-O-?-D-glucopyranoside, ?-mangostin 3-O-?-D-2-deoxyglucopyranoside, ?-mangostin 6-O-?-D-2-deoxyglucopyranoside, and ?-mangostin 3,6-di-O-?-D-2-deoxyglucopyranoside were successfully produced in practical quantities and characterized by high-resolution quadruple time-of-flight electrospray ionization-mass spectrometry (HR-QTOF ESI/MS), (1)H and (13)C NMR analyses. In excess of the substrate, the maximum productions of three ?-mangostin glucopyranosides (4.8 mg/mL, 86.5 % overall conversion of ?-mangostin) and three ?-mangostin 2-deoxyglucopyronosides (4.0 mg/mL, 79 % overall conversion of ?-mangostin) were achieved at 4-h incubation period. All the ?-mangostin glycosides exhibited improved water solubility, and their antibacterial activity against three Gram-positive bacteria Micrococcus luteus, Bacillus subtilis, and Staphylococcus aureus was drastically enhanced by the glucosylation at C-3 position. In this study, diverse glycosylated ?-mangostin were produced in significant quantities by using inexpensive starting materials and recycling co-factors within a reaction vessel without use of expensive NDP-sugars in the glycosylation reactions. PMID:25038930

Le, Tuoi Thi; Pandey, Ramesh Prasad; Gurung, Rit Bahadur; Dhakal, Dipesh; Sohng, Jae Kyung

2014-10-01

80

The ESAT-6 gene cluster of Mycobacterium tuberculosis and other high G+C Gram-positive bacteria  

PubMed Central

Background The genome of Mycobacterium tuberculosis H37Rv has five copies of a cluster of genes known as the ESAT-6 loci. These clusters contain members of the CFP-10 (lhp) and ESAT-6 (esat-6) gene families (encoding secreted T-cell antigens that lack detectable secretion signals) as well as genes encoding secreted, cell-wall-associated subtilisin-like serine proteases, putative ABC transporters, ATP-binding proteins and other membrane-associated proteins. These membrane-associated and energy-providing proteins may function to secrete members of the ESAT-6 and CFP-10 protein families, and the proteases may be involved in processing the secreted peptide. Results Finished and unfinished genome sequencing data of 98 publicly available microbial genomes has been analyzed for the presence of orthologs of the ESAT-6 loci. The multiple duplicates of the ESAT-6 gene cluster found in the genome of M. tuberculosis H37Rv are also conserved in the genomes of other mycobacteria, for example M. tuberculosis CDC1551, M. tuberculosis 210, M. bovis, M. leprae, M. avium, and the avirulent strain M. smegmatis. Phylogenetic analyses of the resulting sequences have established the duplication order of the gene clusters and demonstrated that the gene cluster known as region 4 (Rv3444c-3450c) is ancestral. Region 4 is also the only region for which an ortholog could be found in the genomes of Corynebacterium diphtheriae and Streptomyces coelicolor. Conclusions Comparative genomic analysis revealed that the presence of the ESAT-6 gene cluster is a feature of some high-G+C Gram-positive bacteria. Multiple duplications of this cluster have occurred and are maintained only within the genomes of members of the genus Mycobacterium. PMID:11597336

Gey van Pittius, Nico C; Gamieldien, Junaid; Hide, Winston; Brown, Gordon D; Siezen, Roland J; Beyers, Albert D

2001-01-01

81

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. PMID:22919330

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

82

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

83

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. PMID:23650575

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

2012-01-01

84

In vitro metabolism of 2,2'-diaminopimelic acid from gram-positive and gram-negative bacterial cells by ruminal protozoa and bacteria.  

PubMed Central

Bacillus megaterium GW1 and Escherichia coli W7-M5 were specifically radiolabeled with 2,2'-diamino[G-3H]pimelic acid [( 3H]DAP) as models of gram-positive and gram-negative bacteria, respectively. These radiolabeled bacterial mutants were incubated alone (control) and with mixed ruminal bacteria or protozoa, and the metabolic processes, rates, and patterns of radiolabeled products released from them were studied. Control incubations revealed an inherent difference between the two substrates; gram-positive supernatants consistently contained 5% radioactivity, whereas even at 0 h, those from the gram-negative mutant released 22%. Incubations with ruminal microorganisms showed that the two mutants were metabolized differently and that protozoa were the major effectors of their metabolism. Protozoa exhibited differential rates of engulfment (150 B. megaterium GW1 and 4,290 E. coli W7-M5 organisms per protozoan per h), and they extensively degraded [3H]DAP-labeled B. megaterium GW1 at rates up to nine times greater than those of ruminal bacteria. By contrast, [3H]DAP-labeled E. coli W7-M5 degradation by either ruminal bacteria or ruminal protozoa was more limited. These fundamental differences in the metabolism of the two mutants, especially by ruminal protozoa, were reflected in the patterns and rates of radiolabeled metabolites produced; many were rapidly released from [3H]DAP-labeled B. megaterium GW1, whereas few were slowly released from [3H]DAP-labeled E. coli W7-M5. Most radiolabeled products derived from [3H]DAP-labeled B. megaterium GW1 were peptides of bacterial peptidoglycan origin. The ruminal metabolism of DAP-containing gram-positive and gram-negative bacteria, even with the same peptidoglycan chemotype, is thus likely to be profoundly different.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2495759

Denholm, A M; Ling, J R

1989-01-01

85

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. PMID:15901699

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

86

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

87

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

PubMed

The procedure of obtaining DNA-containing cell envelopes ("micromummies") of bacteria, yeasts, and fungi using chaotropic salts has been developed previously and the possibility of their direct application in PCR has been demonstrated. The fine structure of micromummies has been studied by electron microscopic methods. This work has demonstrated that additional treatment of micromummies of yeasts and gram-positive bacteria with proteinase K results in hydrolytic degradation of cell proteins and drastic enhancement of cell wall permeability for macromolecules (DNA). Thus, the efficiency of PCR ex situ using resultant micromummies after washing off the products of protein hydrolysis and proteinase K can be increased. The results of electron microscopic study of ultrathin sections of yeasts (Pichia pastoris, Saccharomyces cerevisiae) and gram-positive bacteria (Micrococcus luteus, Arthrobacter globiformis, Bacillus subtilis) support the biochemical data that treatment with chaotropic salts and proteinase K results in the loosening of microbial cell walls and in a decrease in the intracellular protein content. At the same time, cell walls generally maintain their integrity (continuity) and initial spherical or rodlike shape. The optimal modes of treatment of the cells of different microbial species with chaotropic salts and proteinase K have been selected to obtain permeabilized cell envelopes containing denatured or native DNA. PMID:17410877

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

2007-01-01

88

Potentiation of photoinactivation of Gram-positive and Gram-negative bacteria mediated by six phenothiazinium dyes by addition of azide ion.  

PubMed

Antimicrobial photodynamic inactivation (APDI) using phenothiazinium dyes is mediated by reactive oxygen species consisting of a combination of singlet oxygen (quenched by azide), hydroxyl radicals and other reactive oxygen species. We recently showed that addition of sodium azide paradoxically potentiated APDI of Gram-positive and Gram-negative bacteria using methylene blue as the photosensitizer, and this was due to electron transfer to the dye triplet state from azide anion, producing azidyl radical. Here we compare this effect using six different homologous phenothiazinium dyes: methylene blue, toluidine blue O, new methylene blue, dimethylmethylene blue, azure A, and azure B. We found both significant potentiation (up to 2 logs) and also significant inhibition (>3 logs) of killing by adding 10 mM azide depending on Gram classification, washing the dye from the cells, and dye structure. Killing of E. coli was potentiated with all 6 dyes after a wash, while S. aureus killing was only potentiated by MB and TBO with a wash and DMMB with no wash. More lipophilic dyes (higher log P value, such as DMMB) were more likely to show potentiation. We conclude that the Type I photochemical mechanism (potentiation with azide) likely depends on the microenvironment, i.e. higher binding of dye to bacteria. Bacterial dye-binding is thought to be higher with Gram-negative compared to Gram-positive bacteria, when unbound dye has been washed away, and with more lipophilic dyes. PMID:25177833

Kasimova, Kamola R; Sadasivam, Magesh; Landi, Giacomo; Sarna, Tadeusz; Hamblin, Michael R

2014-10-15

89

Systematic Review of Membrane Components of Gram-Positive Bacteria Responsible as Pyrogens for Inducing Human Monocyte/Macrophage Cytokine Release  

PubMed Central

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

90

Activity of Bay y3118 against quinolone-susceptible and -resistant gram-negative and gram-positive bacteria.  

PubMed Central

The activity of Bay y3118 against laboratory strains of bacteria, including those with mutations in gyrA, with decreased expression of outer membrane proteins, and/or that are multiply resistant, and 121 selected clinical isolates, including highly fluoroquinolone-resistant bacteria from Spain and Argentina, was determined. Bay y3118 was extremely active (MICs, < or = 1 microgram/ml) against all bacteria, including quinolone-resistant laboratory strains. However, Bay y3118 was less active against 46 of 121 quinolone-resistant clinical isolates, such that > or = 16 micrograms of Bay y3118 per ml was required to inhibit 3 isolates. The concentration of Bay y3118 required to inhibit DNA synthesis by 50% correlated well with the MIC. Bay y3118 had accumulation kinetics similar to those of previously studied fluoroquinolones, e.g., ciprofloxacin, and there was a 50% decrease in the steady-state concentration in those members of the family Enterobacteriaceae that lacked porin proteins. Magnesium chloride at 20 mM apparently abolished the accumulation of Bay y3118 into Escherichia coli and reduced the level of accumulation into other gram-negative bacteria and Staphylococcus aureus. Carbonyl cyanide m-chlorophenylhydrazone at 100 microM enhanced the accumulation of Bay y3118 into E. coli, but it had a minimal effect on accumulation into S. aureus. PMID:8203834

Piddock, L J; Marshall, A J; Jin, Y F

1994-01-01

91

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

92

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

93

Selective toxicity of ZnO nanoparticles toward Gram-positive bacteria and cancer cells by apoptosis through lipid peroxidation  

Microsoft Academic Search

Nanoparticles are increasingly recognized for their utility in biological applications including nanomedicine. The present study investigated the toxicity of zinc oxide (ZnO) nanoparticles toward prokaryotic and eukaryotic cells. Cytotoxicity of ZnO to mammalian cells was studied using human myeloblastic leukemia cells (HL60) and normal peripheral blood mononuclear cells (PBMCs). Antibacterial activity of ZnO was also tested against the Gram-negative bacteria

Mariappan Premanathan; Krishnamoorthy Karthikeyan; Kadarkaraithangam Jeyasubramanian; Govindasamy Manivannan

2011-01-01

94

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. PMID:24459419

Chavasiri, Warinthorn

2013-01-01

95

Comparison of killing of gram-negative and gram-positive bacteria by pure singlet oxygen. [Salmonella typhimurium; Escherichia coli; Sarcina lutea; Staphylococcus aureus; Streptococcus lactis; Streptococcus faecalis  

SciTech Connect

Gram-negative and gram-positive bacteria were found to display different sensitivities to pure singlet oxygen generated outside of cells. Killing curves for Salmonella typhimurium and Escherichia coli strains were indicative of multihit killing, whereas curves for Sarcina lutea, Staphylococcus aureus, Streptococcus lactis, and Streptococcus faecalis exhibited single-hit kinetics. The S. typhimurium deep rough strain TA1975, which lacks nearly all of the cell wall lipopolysaccharide coat and manifests concomitant enhancement of penetration by some exogenous substances, responded to singlet oxygen with initially faster inactivation than did the S. typhimurium wild-type strain, although the maximum rates of killing appeared to be quite similar. The structure of the cell wall thus plays an important role in susceptibility to singlet oxygen. The outer membrane-lipopolysaccharide portion of the gram-negative cell wall initially protects the bacteria from extracellular singlet oxygen, although it may also serve as a source for secondary reaction products which accentuate the rates of cell killing. S. typhimurium and E. coli strains lacking the cellular antioxidant, glutathione, showed no difference from strains containing glutathione in response to the toxic effects of singlet oxygen. Strains of Sarcina lutea and Staphylococcus aureus that contained carotenoids, however, were far more resistant to singlet oxygen lethality than were both carotenoidless mutants of the same species and other gram-positive species lacking high levels of protective carotenoids.

Dahl, T.A.; Midden, W.R. (Bowling Green State Univ., OH (USA)); Hartman, P.E. (Johns Hopkins Univ., Baltimore, MD (USA))

1989-04-01

96

Disinfection of gram-negative and gram-positive bacteria using DynaJets® hydrodynamic cavitating jets.  

PubMed

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. However, different gram-negative species also showed significant differences (P. syringae 6-log(10) reduction, P. aeruginosa 2-log(10) reduction) under the same conditions. Disinfection of E. coli repeatedly showed five orders of magnitude reduction in concentration within 45-60-min at low nozzle pressure (2.1 bar). Optimization of nozzle design and operating pressures increased disinfection rates per input energy by several orders of magnitude. The power efficiencies of the hydrodynamic cavitating jets were found to be 10-100 times greater than comparable ultrasonic systems. PMID:22079473

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

2012-05-01

97

Mechanism of action of sparfloxacin against and mechanism of resistance in gram-negative and gram-positive bacteria.  

PubMed Central

The inhibition of DNA synthesis by sparfloxacin; accumulation of sparfloxacin into members of the family Enterobacteriaceae, Pseudomonas aeruginosa, and staphylococci; induction of recA in Escherichia coli; and the optimum bactericidal concentration (OBC) were measured, and killing kinetics at the OBC were estimated. The OBC and maximum recA-inducing concentration in E. coli were both 1 microgram of sparfloxacin per ml. Accumulation was rapid; two- to threefold more sparfloxacin than ciprofloxacin accumulated in staphylococci and more sparfloxacin accumulated in staphylococci than in gram-negative bacteria. Laboratory mutants with decreased susceptibilities to quinolones alone or multiply resistant were selected from the Enterobacteriaceae and Staphylococcus aureus by using sparfloxacin. PMID:1666499

Piddock, L J; Zhu, M

1991-01-01

98

In vitro activity of biapenem against clinical isolates of gram-positive and gram-negative bacteria.  

PubMed Central

The in vitro activity of biapenem, a new carbapenem previously designated L-627, was compared with those of imipenem and several other antimicrobial agents against 771 clinical bacterial isolates. Against gram-positive organisms, biapenem was found to be approximately as active as imipenem, inhibiting 90% of isolates of most species at concentrations within one dilution of the MIC of imipenem for 90% of the isolates. Against gram-negative organisms and Bacteroides fragilis, biapenem was at least as active as and often more active than imipenem, with MICs for 90% of the isolates two- to eightfold lower than those of imipenem. PMID:8239623

Malanoski, G J; Collins, L; Wennersten, C; Moellering, R C; Eliopoulos, G M

1993-01-01

99

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

PubMed Central

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 cell-surface proteins was identified, which is conserved in a subgroup of gram-positive bacteria. Each gene cluster generally has one copy of four new gene families called cscA, cscB, cscC and cscD. Clusters encoding these cell-surface proteins were found only in complete genomes of Lactobacillus plantarum, Lactobacillus sakei, Enterococcus faecalis, Listeria innocua, Listeria monocytogenes, Lactococcus lactis ssp lactis and Bacillus cereus and in incomplete genomes of L. lactis ssp cremoris, Lactobacillus casei, Enterococcus faecium, Pediococcus pentosaceus, Lactobacillius brevis, Oenococcus oeni, Leuconostoc mesenteroides, and Bacillus thuringiensis. These genes are neither present in the genomes of streptococci, staphylococci and clostridia, nor in the Lactobacillus acidophilus group, suggesting a niche-specific distribution, possibly relating to association with plants. All encoded proteins have a signal peptide for secretion by the Sec-dependent pathway, while some have cell-surface anchors, novel WxL domains, and putative domains for sugar binding and degradation. Transcriptome analysis in L. plantarum shows that the cscA-D genes are co-expressed, supporting their operon organization. Many gene clusters are significantly up-regulated in a glucose-grown, ccpA-mutant derivative of L. plantarum, suggesting catabolite control. This is supported by the presence of predicted CRE-sites upstream or inside the up-regulated cscA-D gene clusters. Conclusion We propose that the CscA, CscB, CscC and CscD proteins form cell-surface protein complexes and play a role in carbon source acquisition. Primary occurrence in plant-associated gram-positive bacteria suggests a possible role in degradation and utilization of plant oligo- or poly-saccharides. PMID:16723015

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

2006-01-01

100

Lysis of gram-positive and gram-negative bacteria by antibacterial porous polymeric monolith formed in microfluidic biochips for sample preparation.  

PubMed

Bacterial cell lysis is demonstrated using polymeric microfluidic biochips operating via a hybrid mechanical shearing/contact killing mechanism. These biochips are fabricated from a cross-linked poly(methyl methacrylate) (X-PMMA) substrate by well-controlled, high-throughput laser micromachining. The unreacted double bonds at the surface of X-PMMA provide covalent bonding for the formation of a porous polymeric monolith (PPM), thus contributing to the mechanical stability of the biochip and eliminating the need for surface treatment. The lysis efficiency of these biochips was tested for gram-positive (Enterococcus saccharolyticus and Bacillus subtilis) and gram-negative bacteria (Escherichia coli and Pseudomonas fluorescens) and confirmed by off-chip PCR without further purification. The influence of the flow rate when pumping the bacterial suspension through the PPM, and of the hydrophobic-hydrophilic balance on the cell lysis efficiency was investigated at a cell concentration of 10(5) CFU/mL. It was shown that the contribution of contact killing to cell lysis was more important than that of mechanical shearing in the PPM. The biochip showed better lysis efficiency than the off-chip chemical, mechanical, and thermal lysis techniques used in this work. The biochip also acts as a filter that isolates cell debris and allows PCR-amplifiable DNA to pass through. The system performs more efficient lysis for gram-negative than for gram-positive bacteria. The biochip does not require chemical/enzymatic reagents, power consumption, or complicated design and fabrication processes, which makes it an attractive on-chip lysis device that can be used in sample preparation for genetics and point-of-care diagnostics. The biochips were reused for 20 lysis cycles without any evidence of physical damage to the PPM, significant performance degradation, or DNA carryover when they were back-flushed between cycles. The biochips efficiently lysed both gram-positive and gram-negative bacteria in about 35 min per lysis and PPM regeneration cycle. PMID:25059724

Aly, Mohamed Aly Saad; Gauthier, Mario; Yeow, John

2014-09-01

101

LiF Reduces MICs of Antibiotics against Clinical Isolates of Gram-Positive and Gram-Negative Bacteria  

PubMed Central

Antibiotic resistance is an ever-growing problem yet the development of new antibiotics has slowed to a trickle, giving rise to the use of combination therapy to eradicate infections. The purpose of this study was to evaluate the combined inhibitory effect of lithium fluoride (LiF) and commonly used antimicrobials on the growth of the following bacteria: Enterococcus faecalis, Staphyloccoccus aureus, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Serratia marcescens, and Streptococcus pneumoniae. The in vitro activities of ceftazidime, sulfamethoxazole-trimethoprim, streptomycin, erythromycin, amoxicillin, and ciprofloxacin, doxycycline, alone or combined with LiF were performed by microdilution method. MICs were determined visually following 18–20?h of incubation at 37°C. We observed reduced MICs of antibiotics associated with LiF ranging from two-fold to sixteen-fold. The strongest decreases of MICs observed were for streptomycin and erythromycin associated with LiF against Acinetobacter baumannii and Streptococcus pneumoniae. An eight-fold reduction was recorded for streptomycin against S. pneumoniae whereas an eight-fold and a sixteen-fold reduction were obtained for erythromycin against A. baumannii and S. pneumoniae. This suggests that LiF exhibits a synergistic effect with a wide range of antibiotics and is indicative of its potential as an adjuvant in antibiotic therapy. PMID:22518143

Syed, H. C.; Ravaoarinoro, M.

2012-01-01

102

Characterisation and in vitro activities of surface attached dihydropyrrol-2-ones against Gram-negative and Gram-positive bacteria.  

PubMed

Bacterial infection of biomedical devices is still a major barrier to their use. This is compounded by increasing antibiotic resistance. Here, the specific covalent attachment of a series of dihydropyrrol-2-one (DHP), analogues of bacterial quorum sensing inhibitors, to surfaces via a Michael-type addition reaction is described. Differences in efficiency of attachment related to the substituent groups were found by X-ray photoelectron spectroscopy. The physical characteristics of the surfaces were further explored by atomic force microscopy and contact angle measurements. The ability of these coatings to prevent the formation of a biofilm by Pseudomonas aeruginosa and Staphylococcus aureus was examined using confocal laser scanning microscopy and image analysis. The DHP-treated surfaces showed significant reductions in bacterial adhesion without increased killing for both strains of bacteria (p < 0.001). 5-Methylene-1-(prop-2-enoyl)-4-phenyl-dihydropyrrol-2-one was identified as having broad spectrum activity and consequently represents an excellent candidate for the development of novel surfaces for the prevention of biomedical device infections. PMID:21038151

Ho, Kitty K K; Cole, Nerida; Chen, Renxun; Willcox, Mark D P; Rice, Scott A; Kumar, Naresh

2010-11-01

103

Antimicrobial effect of the triterpene 3?,6?,16?-trihydroxylup-20(29)-ene on planktonic cells and biofilms from Gram positive and Gram negative bacteria.  

PubMed

This study evaluated the antimicrobial effect of 3?,6?,16?-trihydroxylup-20(29)-ene (CLF1), a triterpene isolated from Combretum leprosum Mart., in inhibiting the planktonic growth and biofilms of Gram positive bacteria Streptococcus mutans and S. mitis. The antimicrobial activity was assessed by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The antibiofilm potential was determined by quantifying total biomass and enumerating biofilm-entrapped viable bacteria. In addition, the acute toxicity of CLF1 on Artemia sp. nauplii was also determined. The results showed that CLF1 was able in inhibiting the growth of S. mutans and S. mitis with MIC and MBC of 7.8 ?g/mL and 15.6 ?g/mL, respectively. CLF1 was highly effective on biofilms of both bacteria. Only 7.8 ?g/mL CLF1 was enough to inhibit by 97% and 90% biomass production of S. mutans and S. mitis, respectively. On the other hand, such effects were not evident on Gram negative Pseudomonas aeruginosa and Klebsiella oxytoca. The toxicity tests showed that the LC50 of CLF1 was 98.19 ?g/mL. Therefore, CLF1 isolated from C. leprosum may constitute an important natural agent for the development of new therapies for caries and other infectious diseases caused by S. mutans and S. mitis. PMID:25093179

Evaristo, Francisco Flávio Vasconcelos; Albuquerque, Maria Rose Jane R; dos Santos, Hélcio Silva; Bandeira, Paulo Nogueira; Avila, Fábio do Nascimento; da Silva, Bruno Rocha; Vasconcelos, Ariana Azevedo; Rabelo, Erica de Menezes; Nascimento-Neto, Luiz Gonzaga; Arruda, Francisco Vassiliepe Sousa; Vasconcelos, Mayron Alves; Carneiro, Victor Alves; Cavada, Benildo Sousa; Teixeira, Edson Holanda

2014-01-01

104

Antimicrobial Effect of the Triterpene 3?,6?,16?-Trihydroxylup-20(29)-ene on Planktonic Cells and Biofilms from Gram Positive and Gram Negative Bacteria  

PubMed Central

This study evaluated the antimicrobial effect of 3?,6?,16?-trihydroxylup-20(29)-ene (CLF1), a triterpene isolated from Combretum leprosum Mart., in inhibiting the planktonic growth and biofilms of Gram positive bacteria Streptococcus mutans and S. mitis. The antimicrobial activity was assessed by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The antibiofilm potential was determined by quantifying total biomass and enumerating biofilm-entrapped viable bacteria. In addition, the acute toxicity of CLF1 on Artemia sp. nauplii was also determined. The results showed that CLF1 was able in inhibiting the growth of S. mutans and S. mitis with MIC and MBC of 7.8??g/mL and 15.6??g/mL, respectively. CLF1 was highly effective on biofilms of both bacteria. Only 7.8??g/mL CLF1 was enough to inhibit by 97% and 90% biomass production of S. mutans and S. mitis, respectively. On the other hand, such effects were not evident on Gram negative Pseudomonas aeruginosa and Klebsiella oxytoca. The toxicity tests showed that the LC50 of CLF1 was 98.19??g/mL. Therefore, CLF1 isolated from C. leprosum may constitute an important natural agent for the development of new therapies for caries and other infectious diseases caused by S. mutans and S. mitis. PMID:25093179

Evaristo, Francisco Flavio Vasconcelos; Albuquerque, Maria Rose Jane R.; dos Santos, Helcio Silva; Bandeira, Paulo Nogueira; Avila, Fabio do Nascimento; da Silva, Bruno Rocha; Vasconcelos, Ariana Azevedo; Rabelo, Erica de Menezes; Nascimento-Neto, Luiz Gonzaga; Arruda, Francisco Vassiliepe Sousa; Vasconcelos, Mayron Alves; Carneiro, Victor Alves; Cavada, Benildo Sousa; Teixeira, Edson Holanda

2014-01-01

105

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. PMID:23970844

Kora, Aruna Jyothi; Rastogi, Lori

2013-01-01

106

Molecular and structural basis of glutathione import in Gram-positive bacteria via GshT and the cystine ABC importer TcyBC of Streptococcus mutans.  

PubMed

Glutathione (GSH) protects cells against oxidative injury and maintains a range of vital functions across all branches of life. Despite recent advances in our understanding of the transport mechanisms responsible for maintaining the spatiotemporal homeostasis of GSH and its conjugates in eukaryotes and Gram-negative bacteria, the molecular and structural basis of GSH import into Gram-positive bacteria has remained largely uncharacterized. Here, we employ genetic, biochemical and structural studies to investigate a possible glutathione import axis in Streptococcus mutans, an organism that has hitherto served as a model system. We show that GshT, a type 3 solute binding protein, displays physiologically relevant affinity for GSH and glutathione disulfide (GSSG). The crystal structure of GshT in complex with GSSG reveals a collapsed structure whereby the GS-I-leg of GSSG is accommodated tightly via extensive interactions contributed by the N- and C-terminal lobes of GshT, while the GS-II leg extends to the solvent. This can explain the ligand promiscuity of GshT in terms of binding glutathione analogues with substitutions at the cysteine-sulfur or the glycine-carboxylate. Finally, we show that GshT primes glutathione import via the L-cystine ABC transporter TcyBC, a membrane permease, which had previously exclusively been associated with the transport of L-cystine. PMID:23701283

Vergauwen, Bjorn; Verstraete, Kenneth; Senadheera, Dilani B; Dansercoer, Ann; Cvitkovitch, Dennis G; Guédon, Eric; Savvides, Savvas N

2013-07-01

107

Efficacy of 5-day parenteral versus intramammary benzylpenicillin for treatment of clinical mastitis caused by gram-positive bacteria susceptible to penicillin in vitro.  

PubMed

The efficacy of parenteral (intramuscular) or intramammary (IMM) benzylpenicillin treatment for clinical mastitis caused by gram-positive bacteria susceptible to penicillin in vitro was investigated. Cows with clinical mastitis in 1 udder quarter were randomly placed into 2 treatment groups. The preliminary bacteriological diagnosis of intramammary infection (IMI) was based on on-farm culturing, and the bacteriological diagnoses were later confirmed by a quantitative PCR assay. Clinical mastitis caused by gram-positive bacteria susceptible to benzylpenicillin was treated with penicillin via either the parenteral route (20mg/kg) or IMM route (600mg) once per day for 5d. The outcome of the treatment was evaluated 3 to 4wk after the onset of the treatment. The affected quarter was examined to assess the clinical cure, and milk samples were collected from the affected quarter to determine the bacteriological cure and milk N-acetyl-?-d-glucosaminidase activity. The survival and the composite milk somatic cell counts of the treated cows were followed up for 6 and 3mo after treatment, respectively. A total of 140 cows with clinical mastitis were included in the study, 61 being treated with benzylpenicillin parenterally and 79 via the IMM route. From all quarters treated, 108 of 140 (77.1%) were cured clinically and 77 of 140 (55.0%) were cured bacteriologically. The route of treatment did not significantly affect the outcome of the treatment; 80.3% of the quarters with parenteral treatment and 74.7% of the quarters with IMM treatment showed a clinical cure, and 54.1 and 55.7% a bacteriological cure, respectively. The milk N-acetyl-?-d-glucosaminidase activity was significantly lower in the quarters with a clinical or bacteriological cure than in the quarters with no cure. The 6-mo survival and the proportion of cows with composite milk somatic cell counts <200,000/mL among the treated cows during the 3-mo follow-up period did not significantly differ between the treatment groups. In conclusion, the outcome of either parenteral or IMM benzylpenicillin treatment of clinical mastitis caused by penicillin-susceptible bacteria was similar. PMID:24485692

Kalmus, P; Simojoki, H; Orro, T; Taponen, S; Mustonen, K; Holopainen, J; Pyörälä, S

2014-04-01

108

High-Throughput System for the Presentation of Secreted and Surface-Exposed Proteins from Gram-Positive Bacteria in Functional Metagenomics Studies  

PubMed Central

Complex microbial ecosystems are increasingly studied through the use of metagenomics approaches. Overwhelming amounts of DNA sequence data are generated to describe the ecosystems, and allow to search for correlations between gene occurrence and clinical (e.g. in studies of the gut microbiota), physico-chemical (e.g. in studies of soil or water environments), or other parameters. Observed correlations can then be used to formulate hypotheses concerning microbial gene functions in relation to the ecosystem studied. In this context, functional metagenomics studies aim to validate these hypotheses and to explore the mechanisms involved. One possible approach is to PCR amplify or chemically synthesize genes of interest and to express them in a suitable host in order to study their function. For bacterial genes, Escherichia coli is often used as the expression host but, depending on the origin and nature of the genes of interest and the test system used to evaluate their putative function, other expression systems may be preferable. In this study, we developed a system to evaluate the role of secreted and surface-exposed proteins from Gram-positive bacteria in the human gut microbiota in immune modulation. We chose to use a Gram-positive host bacterium, Bacillus subtilis, and modified it to provide an expression background that behaves neutral in a cell-based immune modulation assay, in vitro. We also adapted an E. coli – B. subtilis shuttle expression vector for use with the Gateway high-throughput cloning system. Finally, we demonstrate the functionality of this host-vector system through the cloning and expression of a flagellin-coding sequence, and show that the expression-clone elicits an inflammatory response in a human intestinal epithelial cell line. The expression host can easily be adapted to assure neutrality in other assay systems, allowing the use of the presented presentation system in functional metagenomics of the gut and other ecosystems. PMID:23799065

Dobrijevic, Dragana; Di Liberto, Gaetana; Tanaka, Kosei; de Wouters, Tomas; Dervyn, Rozenn; Boudebbouze, Samira; Binesse, Johan; Blottiere, Herve M.; Jamet, Alexandre; Maguin, Emmanuelle; van de Guchte, Maarten

2013-01-01

109

Granular Layer in the Periplasmic Space of Gram-Positive Bacteria and Fine Structures of Enterococcus gallinarum and Streptococcus gordonii Septa Revealed by Cryo-Electron Microscopy of Vitreous Sections  

Microsoft Academic Search

High-resolution structural information on optimally preserved bacterial cells can be obtained with cryo- electron microscopy of vitreous sections. With the help of this technique, the existence of a periplasmic space between the plasma membrane and the thick peptidoglycan layer of the gram-positive bacteria Bacillus subtilis and Staphylococcus aureus was recently shown. This raises questions about the mode of polymerization of

B. Zuber; M. Haenni; T. Ribeiro; K. Minnig; F. Lopes; P. Moreillon; J. Dubochet

2006-01-01

110

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

Microsoft Academic Search

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

Gabriel Vinderola; Chantal Matar; Gabriela Perdigon

2005-01-01

111

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

112

Effects of clinical mastitis caused by gram-positive and gram-negative bacteria and other organisms on the probability of conception in New York State Holstein dairy cows.  

PubMed

The objective of this study was to estimate the effects of different types of clinical mastitis (CM) on the probability of conception in New York State Holstein cows. Data were available on 55,372 artificial inseminations (AI) in 23,695 lactations from 14,148 cows in 7 herds. We used generalized linear mixed models to model whether or not a cow conceived after a particular AI. Independent variables included AI number (first, second, third, fourth), parity, season when AI occurred, farm, type of CM (due to gram-positive bacteria, gram-negative bacteria, or other organisms) in the 6 wk before and after an AI, and occurrence of other diseases. Older cows were less likely to conceive. Inseminations occurring in the summer were least likely to be successful. Retained placenta decreased the probability of conception. Conception was also less likely with each successive AI. The probability of conception associated with the first AI was 0.29. The probability of conception decreased to 0.26, 0.25, and 0.24 for the second, third, and fourth AI, respectively. Clinical mastitis occurring any time between 14 d before until 35 d after an AI was associated with a lower probability of conception; the greatest effect was an 80% reduction associated with gram-negative CM occurring in the week after AI. In general, CM due to gram-negative bacteria had a more detrimental effect on probability of conception than did CM caused by gram-positive bacteria or other organisms. Furthermore, CM had more effect on probability of conception immediately around the time of AI. Additional information about CM (i.e., its timing with respect to AI, and whether the causative agent is gram-positive or gram-negative bacteria, or other organisms) is valuable to dairy personnel in determining why some cows are unable to conceive in a timely manner. These findings are also beneficial for the management of mastitic cows (especially those with gram-negative CM) when mastitis occurs close to AI. PMID:20338432

Hertl, J A; Gröhn, Y T; Leach, J D G; Bar, D; Bennett, G J; González, R N; Rauch, B J; Welcome, F L; Tauer, L W; Schukken, Y H

2010-04-01

113

Susceptibilities of 428 gram-positive and -negative anaerobic bacteria to Bay y3118 compared with their susceptibilities to ciprofloxacin, clindamycin, metronidazole, piperacillin, piperacillin-tazobactam, and cefoxitin.  

PubMed Central

The susceptibilities of 428 gram-negative and gram-positive anaerobes (including selected cefoxitin-resistant strains) to Bay y3118 (a new fluoroquinolone), ciprofloxacin, clindamycin, metronidazole, cefoxitin, piperacillin, and piperacillin-tazobactam were tested. Organisms comprised 115 Bacteroides fragilis group, 116 non-B. fragilis Bacteroides, Prevotella, and Porphyromonas spp., 40 fusobacteria, 58 peptostreptococci, 48 gram-positive non-spore-forming rods, and 51 clostridia. beta-Lactamase production was demonstrated in 87% of the gram-negative rods but in none of the gram-positive organisms. Overall, Bay y3118 was the most active agent, with all organisms inhibited at an MIC of < or = 2.0 micrograms/ml (MICs for 50% [MIC50] and 90% [MIC90] of strains tested, 0.125 and 0.5 microgram/ml, respectively). By contrast, ciprofloxacin was much less active, with only 42% of strains susceptible at a breakpoint of 2.0 micrograms/ml (MIC50, 4.0 micrograms/ml; MIC90, 16.0 micrograms/ml). Metronidazole was active against all gram-negative rods, but 7% of peptostreptococci, 83% of gram-positive non-spore-forming rods, and 4% of non-Clostridium perfringens, non-Clostridium difficile clostridia were resistant to this agent (MICs, > 16.0 micrograms/ml). Clindamycin was active against 94% of Bacteroides, Prevotella, and Porphyromonas spp., 91% of peptostreptococci, and 100% of gram-positive non-spore-forming rods, but was active against only 70% of fusobacteria and 53% of clostridia. Cefoxitin was active against > or = 90% of all groups except the B. fragilis group and non-Propionibacterium acnes gram-positive non-spore-forming rods (both 85%) and C. difficile (20%). Significant enhancement of piperacillin by tazobactam was seen in all beta-lactamase-positive strains (99% susceptible; MIC90, 8.0 micrograms/ml), and all beta-lactamase-negative strains were susceptible to piperacillin (MIC90, 8.0 micrograms/ml). Clinical studies are required to delineate the role of Bay y3118 in the treatment of anaerobic infections. PMID:8215278

Pankuch, G A; Jacobs, M R; Appelbaum, P C

1993-01-01

114

In vitro Activity of Cefdinir (FK482) and Ten Other Antibiotics against Gram-Positive and Gram-Negative Bacteria Isolated from Adult and Pediatric Patients  

Microsoft Academic Search

The in vitro activity of cefdinir, an oral aminothiazolyl hy-droxyimino cephalosporin was compared with that of cefixime, cefpodoxime, cefaclor, cephalexin, ciprofloxacin, ofloxacin, oxacillin, ampicillin, vancomycin and trimethoprim-sulfamethoxazole against 279 gram-positive and gram-negative recent clinical isolates from adult and pediatric patients. Cefdinir was the most active drug among the cephalosporins against oxacil-lin-sensitive Staphylococcus aureus and coagulase-negative staphylococci, Streptococcus pneumoniae, S. pyogenes,

Tanveer Sultan; Aldona L. Baltch; Raymond P. Smith; William Ritz

1994-01-01

115

Isolation and characterization of four novel Gram-positive bacteria associated with the rhizosphere of two endemorelict plants capable of degrading a broad range of aromatic substrates  

Microsoft Academic Search

Four new Gram-positive, phenol-degrading strains were isolated from the rhizospheres of endemorelict plants Ramonda serbica and Ramonda nathaliae known to exude high amounts of phenolics in the soil. Isolates were designated Bacillus sp. PS1, Bacillus sp. PS11, Streptomyces sp. PS12, and Streptomyces sp. PN1 based on 16S rDNA sequence and biochemical analysis. In addition to their ability to tolerate and

Lidija Djokic; Tanja Narancic; Jasmina Nikodinovic-Runic; Miloje Savic; Branka Vasiljevic

2011-01-01

116

Antibacterial activity of Lactobacillus acidophilus strains isolated from honey marketed in Malaysia against selected multiple antibiotic resistant (MAR) Gram-positive bacteria.  

PubMed

A total of 32 lactic acid bacteria (LAB) were isolated from 13 honey samples commercially marketed in Malaysia, 6 strains identified as Lactobacillus acidophilus by API CHL50. The isolates had antibacterial activities against multiple antibiotic resistant's Staphylococcus aureus (25 to 32 mm), Staphylococcus epidermis (14 to 22 mm) and Bacillus subtilis (12 to 19 mm) in the agar overlay method after 24 h incubation at 30 °C. The crude supernatant was heat stable at 90 °C and 121 °C for 1 h. Treatment with proteinase K and RNase II maintained the antimicrobial activity of all the supernatants except sample H006-A and H010-G. All the supernatants showed antimicrobial activities against target bacteria at pH 3 and pH 5 but not at pH 6 within 72 h incubation at 30 °C. S. aureus was not inhibited by sample H006-A isolated from Libyan honey and sample H008-D isolated from Malaysian honey at pH 5, compared to supernatants from other L. acidophilus isolates. The presence of different strains of L. acidophilus in honey obtained from different sources may contribute to the differences in the antimicrobial properties of honey. PMID:22757710

Aween, Mohamed Mustafa; Hassan, Zaiton; Muhialdin, Belal J; Eljamel, Yossra A; Al-Mabrok, Asma Saleh W; Lani, Mohd Nizam

2012-07-01

117

Granular Layer in the Periplasmic Space of Gram-Positive Bacteria and Fine Structures of Enterococcus gallinarum and Streptococcus gordonii Septa Revealed by Cryo-Electron Microscopy of Vitreous Sections  

PubMed Central

High-resolution structural information on optimally preserved bacterial cells can be obtained with cryo-electron microscopy of vitreous sections. With the help of this technique, the existence of a periplasmic space between the plasma membrane and the thick peptidoglycan layer of the gram-positive bacteria Bacillus subtilis and Staphylococcus aureus was recently shown. This raises questions about the mode of polymerization of peptidoglycan. In the present study, we report the structure of the cell envelope of three gram-positive bacteria (B. subtilis, Streptococcus gordonii, and Enterococcus gallinarum). In the three cases, a previously undescribed granular layer adjacent to the plasma membrane is found in the periplasmic space. In order to better understand how nascent peptidoglycan is incorporated into the mature peptidoglycan, we investigated cellular regions known to represent the sites of cell wall production. Each of these sites possesses a specific structure. We propose a hypothetic model of peptidoglycan polymerization that accommodates these differences: peptidoglycan precursors could be exported from the cytoplasm to the periplasmic space, where they could diffuse until they would interact with the interface between the granular layer and the thick peptidoglycan layer. They could then polymerize with mature peptidoglycan. We report cytoplasmic structures at the E. gallinarum septum that could be interpreted as cytoskeletal elements driving cell division (FtsZ ring). Although immunoelectron microscopy and fluorescence microscopy studies have demonstrated the septal and cytoplasmic localization of FtsZ, direct visualization of in situ FtsZ filaments has not been obtained in any electron microscopy study of fixed and dehydrated bacteria. PMID:16952957

Zuber, Benoit; Haenni, Marisa; Ribeiro, Tania; Minnig, Kathrin; Lopes, Fatima; Moreillon, Philippe; Dubochet, Jacques

2006-01-01

118

Granular layer in the periplasmic space of gram-positive bacteria and fine structures of Enterococcus gallinarum and Streptococcus gordonii septa revealed by cryo-electron microscopy of vitreous sections.  

PubMed

High-resolution structural information on optimally preserved bacterial cells can be obtained with cryo-electron microscopy of vitreous sections. With the help of this technique, the existence of a periplasmic space between the plasma membrane and the thick peptidoglycan layer of the gram-positive bacteria Bacillus subtilis and Staphylococcus aureus was recently shown. This raises questions about the mode of polymerization of peptidoglycan. In the present study, we report the structure of the cell envelope of three gram-positive bacteria (B. subtilis, Streptococcus gordonii, and Enterococcus gallinarum). In the three cases, a previously undescribed granular layer adjacent to the plasma membrane is found in the periplasmic space. In order to better understand how nascent peptidoglycan is incorporated into the mature peptidoglycan, we investigated cellular regions known to represent the sites of cell wall production. Each of these sites possesses a specific structure. We propose a hypothetic model of peptidoglycan polymerization that accommodates these differences: peptidoglycan precursors could be exported from the cytoplasm to the periplasmic space, where they could diffuse until they would interact with the interface between the granular layer and the thick peptidoglycan layer. They could then polymerize with mature peptidoglycan. We report cytoplasmic structures at the E. gallinarum septum that could be interpreted as cytoskeletal elements driving cell division (FtsZ ring). Although immunoelectron microscopy and fluorescence microscopy studies have demonstrated the septal and cytoplasmic localization of FtsZ, direct visualization of in situ FtsZ filaments has not been obtained in any electron microscopy study of fixed and dehydrated bacteria. PMID:16952957

Zuber, Benoît; Haenni, Marisa; Ribeiro, Tânia; Minnig, Kathrin; Lopes, Fátima; Moreillon, Philippe; Dubochet, Jacques

2006-09-01

119

?-Alkylidene-?-lactones and isobutylpyrrol-2(5H)-ones analogues to rubrolides as inhibitors of biofilm formation by gram-positive and gram-negative bacteria.  

PubMed

Several molecules have been discovered that interfere with formation of bacterial biofilms, opening a new strategy for the development of more efficient treatments in case of antibiotic resistant bacteria. Amongst the most active compounds are some natural brominated furanones from marine algae Delisea pulchra that have proven to be able to control pathogenic biofilms. We have recently reported that some rubrolide analogues are able to inhibit biofilm formation of Enterococcus faecalis. In the present Letter we describe results of the biological evaluation of a small library of 28 compounds including brominated furanones and the corresponding lactams against biofilm formation of Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis and Streptococcus mutans. Our results showed that in general these compounds were more active against biofilms of S. epidermidis and P. aeruginosa, with little or no inhibition of planktonic bacterial growth. In some cases they were able to prevent biofilm formation of P. aeruginosa at concentrations as low as 0.6 ?g/mL (1.3 ?M, compound 3d) and 0.7 ?g/mL (1.3 ?M, 3f). Results also indicate that, in general, lactams are more active against biofilms than their precursors, thus designating this class of molecules as good candidates for the development of a new generation of antimicrobial drugs targeted to biofilm inhibition. PMID:24484899

Pereira, Ulisses A; Barbosa, Luiz C A; Maltha, Célia R A; Demuner, Antônio J; Masood, Mohammed A; Pimenta, Andréa L

2014-02-15

120

Isolation and characterization of four novel Gram-positive bacteria associated with the rhizosphere of two endemorelict plants capable of degrading a broad range of aromatic substrates.  

PubMed

Four new Gram-positive, phenol-degrading strains were isolated from the rhizospheres of endemorelict plants Ramonda serbica and Ramonda nathaliae known to exude high amounts of phenolics in the soil. Isolates were designated Bacillus sp. PS1, Bacillus sp. PS11, Streptomyces sp. PS12, and Streptomyces sp. PN1 based on 16S rDNA sequence and biochemical analysis. In addition to their ability to tolerate and utilize high amounts of phenol of either up to 800 or up to 1,400 mg l(-1) without apparent inhibition in growth, all four strains were also able to degrade a broad range of aromatic substrates including benzene, toluene, ethylbenzene, xylenes, styrene, halogenated benzenes, and naphthalene. Isolates were able to grow in pure culture and in defined mixed culture on phenol and on the mixture of BTEX (benzene, toluene, ethylbenzene, and xylenes) compounds as a sole source of carbon and energy. Pure culture of Bacillus sp. PS11 yielded 1.5-fold higher biomass amounts in comparison to mixed culture, under all conditions. Strains successfully degraded phenol in the soil model system (2 g kg(-1)) within 6 days. Activities of phenol hydroxylase, catechol 1,2-dioxygenase, and catechol 2,3-dioxygenase were detected and analyzed from the crude cell extract of the isolates. While all four strains use ortho degradation pathway, enzyme indicative of meta degradation pathway (catechol 2,3-dioxygenase) was also detected in Bacillus sp. PS11 and Streptomyces sp. PN1. Phenol degradation activities were induced 2 h after supplementation by phenol, but not by catechol. Catechol slightly inhibited activity of catechol 2,3-dioxygenase in strains PS11 and PN1. PMID:21706169

Djokic, Lidija; Narancic, Tanja; Nikodinovic-Runic, Jasmina; Savic, Miloje; Vasiljevic, Branka

2011-08-01

121

ef1097 and ypkK encode enterococcin V583 and corynicin JK, members of a new family of antimicrobial proteins (bacteriocins) with modular structure from Gram-positive bacteria.  

PubMed

Unlike the colicins, microcins and related peptide antibiotics, little is known about antibiotic proteins (M(r)>10,000) from Gram-positive bacteria, since only few examples have been described to date. In this study we used heterologous expression of recombinant proteins to access the 17 kDa antibiotic protein SA-M57 from Streptococcus pyogenes, along with two proteins of unknown function identified in publicly available databases: EF1097 from Enterococcus faecalis and YpkK from Corynebacterium jeikeium. Here we show that all three are antibiotic proteins with different spectra of antimicrobial activity that kill sensitive bacteria at nanomolar concentrations. In silico structure predictions indicate that although the three proteins share little sequence similarity, they may be composed of conserved secondary structural elements: a relatively unstructured, acidic N-terminal portion and a basic C-terminal portion characterized by two helical elements separated by a loop structure and stabilized by an essential disulphide. Expression of individual segments as well as protein chimaeras revealed that, at least in the case of YpkK, the C-terminal portion is responsible for the killing action of the protein, whereas the role of the N-terminal portion remains unclear. Both scnM57 and ef1097 appear to be widely distributed in Strep. pyogenes and Ent. faecalis (respectively), whereas ypkK is found only rarely amongst clinical isolates of C. jeikeium. Finally, we determined that the proteins kill sensitive bacteria without lysis, a feature that distinguishes them from known murolytic proteins. PMID:17906121

Swe, Pearl M; Heng, Nicholas C K; Ting, Yi-Tian; Baird, Hayley J; Carne, Alan; Tauch, Andreas; Tagg, John R; Jack, Ralph W

2007-10-01

122

The effect of recurrent episodes of clinical mastitis caused by gram-positive and gram-negative bacteria and other organisms on mortality and culling in Holstein dairy cows.  

PubMed

The objective of this study was to estimate the effects of recurrent episodes of different types of clinical mastitis (CM) caused by gram-positive (Streptococcus spp., Staphylococcus aureus, Staphylococcus spp.) and gram-negative (Escherichia coli, Klebsiella, Citrobacter, Enterobacter, Pseudomonas) bacteria, and other organisms (Arcanobacterium pyogenes, Mycoplasma, Corynebacterium bovis, yeast, miscellaneous) on the probability of mortality and culling in Holstein dairy cows. Data from 30,233 lactations in cows of 7 dairy farms in New York State were analyzed. Cows were followed for the first 10 mo in lactation, or until death or culling occurred, or until the end of our study period. Generalized linear mixed models with a Poisson error distribution were used to study the effects of recurrent cases of the different types of CM and several other factors (herd, parity, month of lactation, current year and season, profitability, net replacement cost, other diseases) on cows' probability of death (model 1) or being culled (model 2). Primiparous and multiparous cows were modeled separately because they had different risks of mortality and culling and potentially different CM effects on mortality and culling. Approximately 30% of multiparous cows had at least one case of CM in lactation compared with 16.6% of primiparous cows. Multipara also had higher lactational incidence risks of second (10.7%) and third (4.4%) cases than primipara (3.7% and 1.1%, respectively). For primipara, CM increased the probability of death, with each successive case occurring in a month being increasingly lethal. In multipara, gram-negative CM increased the probability of death, especially when the gram-negative case was the first or second CM case in lactation. Primiparous cows with CM were more likely to be culled after CM than if they did not have CM, particularly after a second or third case. In multipara, any type of CM increased the probability of being culled. Gram-negative CM cases were associated with the numerically highest risk of culling. PMID:21943738

Hertl, J A; Schukken, Y H; Bar, D; Bennett, G J; González, R N; Rauch, B J; Welcome, F L; Tauer, L W; Gröhn, Y T

2011-10-01

123

Genetic transformation in bacteria  

Microsoft Academic Search

Certain species of bacteria can become competent to take up high molecular weight DNA from the surrounding medium. DNA homologous\\u000a to resident chromosomal DNA is transported, processed and recombined with the resident DNA. There are some variations in steps\\u000a leading to transformation between Gram-positive bacteria likebiplococcus pneumoniae and Gram-negative bacteria represented byHaemophilus influenzae but the integration is by single-strand displacement

N. K. Notani; V. P. Joshi; R. P. Kanade

1984-01-01

124

Transcriptional Cross-Regulation between Gram-Negative and Gram-Positive Bacteria, Demonstrated Using ArgP-argO of Escherichia coli and LysG-lysE of Corynebacterium glutamicum  

PubMed Central

The protein-gene pairs ArgP-argO of Escherichia coli and LysG-lysE of Corynebacterium glutamicum are orthologous, with the first member of each pair being a LysR-type transcriptional regulator and the second its target gene encoding a basic amino acid exporter. Whereas LysE is an exporter of arginine (Arg) and lysine (Lys) whose expression is induced by Arg, Lys, or histidine (His), ArgO exports Arg alone, and its expression is activated by Arg but not Lys or His. We have now reconstituted in E. coli the activation of lysE by LysG in the presence of its coeffectors and have shown that neither ArgP nor LysG can regulate expression of the noncognate orthologous target. Of several ArgP-dominant (ArgPd) variants that confer elevated Arg-independent argO expression, some (ArgPd-P274S, -S94L, and, to a lesser extent, -P108S) activated lysE expression in E. coli. However, the individual activating effects of LysG and ArgPd on lysE were mutually extinguished when both proteins were coexpressed in Arg- or His-supplemented cultures. In comparison with native ArgP, the active ArgPd variants exhibited higher affinity of binding to the lysE regulatory region and less DNA bending at both argO and lysE. We conclude that the transcription factor LysG from a Gram-positive bacterium, C. glutamicum, is able to engage appropriately with the RNA polymerase from a Gram-negative bacterium, E. coli, for activation of its cognate target lysE in vivo and that single-amino-acid-substitution variants of ArgP can also activate the distantly orthologous target lysE, but by a subtly different mechanism that renders them noninterchangeable with LysG. PMID:22904281

Marbaniang, Carmelita N.

2012-01-01

125

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.

1996-01-09

126

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.

Ingram, Lonnie O'Neal (Gainesville, FL); Barbosa-Alleyne, Maria D. F. (Gainesville, FL)

1996-01-01

127

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

128

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.

Ingram, Lonnie O'Neal (Gainesville, FL); Barbosa-Alleyne, Maria D. F. (Gainesville, FL)

1999-01-01

129

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

130

Viable but Not Cultivable Bacteria  

Microsoft Academic Search

A well-studied, long-term survival mechanism employed by Gram-positive bacteria is formation of endospores. For Gram-negative\\u000a bacteria, the assumption has been that a survival state does not exist. However, a dormancy state has been described for Gram-negative\\u000a bacteria and designated as the viable but nonculturable (VBNC) strategy of nonspore-forming cells. A variety of environmental\\u000a factors are involved in induction of the

Rita R. Colwell

131

Is Mycobacterium tuberculosis a closer relative to Gram-positive or Gram–negative bacterial pathogens?  

Microsoft Academic Search

The phylogenetic position of Mycobacterium tuberculosis relative to other bacteria is controversial. Its cell wall has characteristics of both Gram-positive and Gram-negative bacteria. In the standard reference of bacterial phylogeny based on 16S ribosomal RNA sequence comparison, M. tuberculosis belongs to the high G+C Gram-positive bacteria that form a monophyletic group with the low G+C Gram-positive bacteria such as Bacillus

L. M Fu; C. S Fu-Liu

2002-01-01

132

Crystallography of Gram-Positive Bacterial Adhesins  

Microsoft Academic Search

\\u000a Both Gram-negative and Gram-positive pathogens display a multitude of proteins and protein assemblies (pili or fimbriae) on\\u000a their cell surfaces, which are often used for adherence and initiate colonization and pathogenesis. Adhesive proteins known\\u000a as MSCRAMMs (microbial surface components recognizing adhesive matrix molecules), anchored by a specific enzyme called sortase\\u000a in Gram-positive bacteria, target the host’s extracellular matrix proteins (ECM)

Vengadesan Krishnan; Sthanam V. L. Narayana

133

Allolysis in bacteria  

Microsoft Academic Search

The review deals with the phenomenon of allolysis, i.e., lysis of a part of a bacterial population induced by a group of epigenetically\\u000a differentiated cells of the same species or phylotype. Allolysis is best studied in two species of gram-positive bacteria,\\u000a Streptococcus pneumoniae and Bacillus subtilis. In S. pneumoniae, allolysis is associated with the onset of the competence stage, while

A. A. Prozorov; V. N. Danilenko

2011-01-01

134

Bacteria Museum  

NSDL National Science Digital Library

Who knew that bacteria had their own virtual museum? Here, visitors will "learn that not all bacteria are harmful, how they are used in industry, that they belong to the oldest living creatures on Earth", and many more interesting facts to discover about the diverse world of bacteria. The "Bacterial Species Files" tab at the top of the page, allows visitors to look up information on 40 different specific bacteria, from Anthrax to Yersinia enterocolitica. The information provided for each bacterium includes photographs, consumer guides, fact sheets, and scientific links. Visitors will find that the "Main Exhibits" tab addresses the basics about bacteria, as well as "Pathogenic Bacteria", "Evolution", "How We Fight Bacteria", and "Food and Water Safety". Visitors will surely enjoy the "Good Bacteria in Food" link found in the Food and Water Safety section, as it explains how some foods benefit from good bacteria, such as Swiss cheese, sausage, sauerkraut, chocolate, and coffee.

135

Bacteria Transformation  

NSDL National Science Digital Library

Students construct paper recombinant plasmids to simulate the methods genetic engineers use to create modified bacteria. They learn what role enzymes, DNA and genes play in the modification of organisms. For the particular model they work on, they isolate a mammal insulin gene and combine it with a bacteria's gene sequence (plasmid DNA) for production of the protein insulin.

National Science Foundation GK-12 and Research Experience for Teachers (RET) Programs,

136

Effect of Diet on Amino and Nucleic Acids of Rumen Bacteria and Protozoa1  

Microsoft Academic Search

Amino acid composition and nucleic acid content of pure cultures of rumen bacteria (17 species) were analyzed. Amino acid composition between gram- positive and -negative organisms was not different. The total nitrogen content of gram-negative bacteria (10.8%) was signif- icantly higher than gram-positive or- ganisms (9.9%). Deoxyribonucleic acid- nitrogen:total nitrogen (rag\\/g) differed between gram-positive (8.8) and gram- negative (18.9) bacteria,

M. J. Arambel; E. E. Bartley; G. S. Dufva; T. G. Nagaraja; A. D. Dayton

1982-01-01

137

Methanotrophic bacteria.  

PubMed Central

Methane-utilizing bacteria (methanotrophs) are a diverse group of gram-negative bacteria that are related to other members of the Proteobacteria. These bacteria are classified into three groups based on the pathways used for assimilation of formaldehyde, the major source of cell carbon, and other physiological and morphological features. The type I and type X methanotrophs are found within the gamma subdivision of the Proteobacteria and employ the ribulose monophosphate pathway for formaldehyde assimilation, whereas type II methanotrophs, which employ the serine pathway for formaldehyde assimilation, form a coherent cluster within the beta subdivision of the Proteobacteria. Methanotrophic bacteria are ubiquitous. The growth of type II bacteria appears to be favored in environments that contain relatively high levels of methane, low levels of dissolved oxygen, and limiting concentrations of combined nitrogen and/or copper. Type I methanotrophs appear to be dominant in environments in which methane is limiting and combined nitrogen and copper levels are relatively high. These bacteria serve as biofilters for the oxidation of methane produced in anaerobic environments, and when oxygen is present in soils, atmospheric methane is oxidized. Their activities in nature are greatly influenced by agricultural practices and other human activities. Recent evidence indicates that naturally occurring, uncultured methanotrophs represent new genera. Methanotrophs that are capable of oxidizing methane at atmospheric levels exhibit methane oxidation kinetics different from those of methanotrophs available in pure cultures. A limited number of methanotrophs have the genetic capacity to synthesize a soluble methane monooxygenase which catalyzes the rapid oxidation of environmental pollutants including trichloroethylene. PMID:8801441

Hanson, R S; Hanson, T E

1996-01-01

138

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. PMID:8993861

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

1997-01-01

139

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

140

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

141

Bioelectricity Aware of bacteria  

E-print Network

Bioelectricity Aware of bacteria Bacteria of the genus Geobacter carry out anaerobic respiration the mechanism that makes these bacteria conductors of electricity. Researchers have studied this for a population of G. sulfurreducens, endowed with bacteria nanometric filaments (pili) that enable them

Lovley, Derek

142

Bacteria TMDL Projects  

E-print Network

of the projects are listed below. ? Peach CreekWater Quality Improvement Project ? Monitoring and Educational Programs Focused on Bacteria and Nutrient Runoff on Dairy Operations in the LeonWatershed ? Development of the Plum CreekWPP ? Impact of Proper... above Canyon Lake: A TMDL Project for Bacteria ? Houston Metropolitan Area: A TMDL Project for Bacteria ? Leon River below Proctor Lake ? Northwest Houston Area Bacteria TMDL Project ? Oso Bay and Oso Creek: A TMDL Project for Bacteria ? Peach...

Wythe, Kathy

2007-01-01

143

Control of Cell Morphogenesis in Bacteria  

Microsoft Academic Search

Cell shape in most eubacteria is maintained by a tough external peptidoglycan cell wall. Recently, cell shape determining proteins of the MreB family were shown to form helical, actin-like cables in the cell. We used a fluorescent derivative of the antibiotic vancomycin as a probe for nascent peptidoglycan synthesis in unfixed cells of various Gram-positive bacteria. In the rod-shaped bacterium

Richard A. Daniel; Jeff Errington

2003-01-01

144

Cadmium uptake and resistance among selected bacteria  

SciTech Connect

The purpose of this research was to determine the relationship between Cd resistance and Cd uptake by lake sediment bacteria. For the Gram positive and gram negative sediment bacteria that were tested, the relationship between resistance and Cd uptake varied and was dependent on the isolate under consideration. Results of this study indicated that bacterial communities in lake sediments may influence the concentration and availability of Cd in sediments and the water column. In addition, results of this study did not support the theory that the genes encoding for Cd resistance are usually carried on antibiotic resistance plasmids.

Burke, B.E.

1987-01-01

145

Bacteria isolated from amoebae/bacteria consortium  

DOEpatents

New protozoan derived microbial consortia and method for their isolation are provided. Consortia and bacteria isolated therefrom are useful for treating wastes such as trichloroethylene and trinitrotoluene. Consortia, bacteria isolated therefrom, and dispersants isolated therefrom are useful for dispersing hydrocarbons such as oil, creosote, wax, and grease.

Tyndall, R.L.

1995-05-30

146

Peptides 25 (2004) 14251440 Peptide signal molecules and bacteriocins in Gram-negative bacteria: a  

E-print Network

-negative bacteria: a genome-wide in silico screening for peptides containing a double-glycine leader sequence Abstract Quorum sensing (QS) in Gram-negative bacteria is generally assumed to be mediated by N-acyl-homoserine lactone molecules while Gram-positive bacteria make use of signaling peptides. We analyzed the occurrence

147

?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

148

[Viable non-culturable bacteria].  

PubMed

Viable but non-culturable cells (VBNC) are defined as live bacteria, but which do not either grow or divide. Such bacteria cannot be cultivated on conventional media (they do not form colonies on solid media, they do not change broth appearance), but their existence can be proved using other methods. The switch to the VBNC stage has been described and documented for several bacterial species: Vibrio spp. (cholerae, vulnificus and other species), Escherichia coli (including EHEC), Campylobacter jejuni, Helicobacter pylori, Salmonella spp., Listeria monocytogenes, Yersinia enterocolytica, Shigella spp., Klebsiella spp., Enterobacter spp., Cronobacter spp., Staphylococcus aureus, Providencia spp., Morganella spp., Pseudomonas spp., Mycobacterium tuberculosis, Enterococcus spp. The capacity of both Gram-positive and Gram-negative bacteria to enter the VBNC stage started to concern microbiologists in the field of food industry (food and water safety) and pharmaceutical industry. Many studies have shown that processes meant to achieve bactericidal effects can favour bacterial switch to VBNC. Viable but non-culturable stage is reversible. Concerns are due to the capacity of VBNC, especially of potentially pathogen cells, to switch to the infectious stage once in the host organism. PMID:21038700

N??cu?iu, Alexandra-Maria

2010-01-01

149

Studies on ozone initiated inactivation of pathogenic bacteria in aqueous systems.  

E-print Network

??The effect of ozone on the inactivation of two Gram-negative strains (Escherichia coli and Pseudomonas aeruginosa) and one Gram-positive endospore (Bacillus subtilis) bacteria, often present… (more)

Zuma, Favourite N.

2008-01-01

150

Control of the spread of multi-resistant Gram-positive organisms  

Microsoft Academic Search

Antibiotic-resistant bacteria have always restricted the use of antibiotics, but in recent years such organisms have caused increasing concern as the development of new classes of antimicrobial has slowed, whilst the ability of bacteria to become resistant has not. Multiple antibiotic-resistant Gram-positive organisms represent a microbiological problem quite different from their Gram-negative counterparts. In the case of the Gram-negative bacteria,

S. P. Barrett

1999-01-01

151

Various functions of selenols and thiols in anaerobic gram-positive, amino acids-utilizing bacteria.  

PubMed

Electron transfer reactions for the reduction of glycine in Eubacterium acidaminophilum involve many selenocysteine (U)- and thiol-containing proteins, as shown by biochemical and molecular analysis. These include an unusual thioredoxin system (-CXXC-), protein A (-CXXU-) and the substrate-specific protein B of glycine reductase (-UXXCXXC-). Most probably a selenoether is formed at protein B by splitting the C-N-bond after binding of the substrate. The carboxymethyl group is then transferred to the selenocysteine of protein A containing a conserved motif. The latter protein acts as a carbon and electron donor by giving rise to a protein C-bound acetyl-thioester and a mixed selenide-sulfide bond at protein A that will be reduced by the thioredoxin system. The dithiothreitol-dependent D-proline reductase of Clostridium sticklandii exhibits many similarities to protein B of glycine reductase including the motif containing selenocysteine. In both cases proprotein processing at a cysteine residue gives rise to a blocked N-terminus, most probably a pyruvoyl group. Formate dehydrogenase and some other proteins from E. acidaminophilum contain selenocysteine, e.g., a 22 kDa protein showing an extensive homology to peroxiredoxins involved in the detoxification of peroxides. PMID:10609892

Andreesen, J R; Wagner, M; Sonntag, D; Kohlstock, M; Harms, C; Gursinsky, T; Jäger, J; Parther, T; Kabisch, U; Gräntzdörffer, A; Pich, A; Söhling, B

1999-01-01

152

Isolation of entomopathogenic gram positive spore forming bacteria effective against coleoptera.  

E-print Network

??Fourteen spore-forming bacterial strains were isolated and screened for entomopathogenic activity. Five displayed toxicity towards the common mealworm, Tenebrio molitor L., (Coleoptera: Tenebrionidae). The majority… (more)

Du Rand, Nicolette.

2009-01-01

153

Antibacterial Activity of Glutathione-Coated Silver Nanoparticles against Gram Positive and Gram Negative Bacteria  

E-print Network

systems (iii) causing damage in respiration, (iv) perturbation of cellular growth, and (v) interaction. Interference in bacterial cell replication is observed for both cellular strains when exposed to GSH stabilized and other cell constituents (ii) causing K+ loss from the membrane, with disruption of cellular transport

154

Protamine-induced permeabilization of cell envelopes of gram-positive and gram-negative bacteria  

Microsoft Academic Search

The inhibitory effect of the cationic peptide protamine on Listeria monocytogenes, Escherichia coli, and Shewanella putrefacienshas been studied in detail. The addition of protamine (10 to 1,000 mg\\/ml) resulted in inhibition of oxygen consumption after less than 1 min and loss of intracellular carboxyfluorescein and ATP after 2 to 5 min. Maximum antibacterial activity was reached at alkaline pH and

CHARLOTTE JOHANSEN; ANNETTE VERHEUL; LONE GRAM; TOM GILL; T. Abee

1997-01-01

155

The phage-related chromosomal islands of Gram-positive bacteria  

PubMed Central

The phage-related chromosomal islands (PRCIs) were first identified in Staphylococcus aureus as highly mobile, superantigen-encoding genetic elements known as the S. aureus pathogenicity islands (SaPIs). These elements are characterized by a specific set of phage-related functions that enable them to use the phage reproduction cycle for their own transduction and inhibit phage reproduction in the process. SaPIs produce many phage-like infectious particles; their streptococcal counterparts have a role in gene regulation but may not be infectious. These elements therefore represent phage satellites or parasites, not defective phages. In this Review, we discuss the shared genetic content of PRCIs, their life cycle and their ability to be transferred across large phylogenetic distances. PMID:20634809

Novick, Richard P.; Christie, Gail E.; Penades, Jose R.

2012-01-01

156

In vitro conjugal transfer of tetracycline resistance from Lactobacillus isolates to other Gram-positive bacteria  

E-print Network

for the dissemination of antibiotic resistance deter- minants via the food chain to the consumer [1]. In addi- tion of transfer along the food chain merits further research. � 2003 Published by Elsevier Science B.V. on behalf in foods and are members of the resident micro£ora of the gastrointestinal tract of hu- mans and animals

Gent, Universiteit

157

Invariant natural killer T cells recognize glycolipids from pathogenic Gram-positive bacteria  

Microsoft Academic Search

Natural killer T cells (NKT cells) recognize glycolipid antigens presented by CD1d. These cells express an evolutionarily conserved, invariant T cell antigen receptor (TCR), but the forces that drive TCR conservation have remained uncertain. Here we show that NKT cells recognized diacylglycerol-containing glycolipids from Streptococcus pneumoniae, the leading cause of community-acquired pneumonia, and group B Streptococcus, which causes neonatal sepsis

Yuki Kinjo; Petr Illarionov; José Luis Vela; Bo Pei; Enrico Girardi; Xiangming Li; Yali Li; Masakazu Imamura; Yukihiro Kaneko; Akiko Okawara; Yoshitsugu Miyazaki; Anaximandro Gómez-Velasco; Paul Rogers; Samira Dahesh; Satoshi Uchiyama; Archana Khurana; Kazuyoshi Kawahara; Hasan Yesilkaya; Peter W Andrew; Chi-Huey Wong; Kazuyoshi Kawakami; Victor Nizet; Gurdyal S Besra; Moriya Tsuji; Dirk M Zajonc; Mitchell Kronenberg

2011-01-01

158

The identification of anaerobic bacteria using MALDI-TOF MS  

Microsoft Academic Search

Matrix Assisted Laser Desorption and Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) has gained more and more popularity for the identification of bacteria. Several studies show that bacterial diagnosticis is being revolutionized by the application of MALDI-TOF MS. For anaerobic bacteria, MALDI-TOF MS has been used for the identification of Prevotella spp., Fusobacterium spp., Clostridium spp., Bacteroides spp. and Gram-positive anaerobic

A. C. M. Veloo; G. W. Welling; J. E. Degener

2011-01-01

159

The Drosophila immune system detects bacteria through specific peptidoglycan recognition  

Microsoft Academic Search

The Drosophila immune system discriminates between different classes of infectious microbes and responds with pathogen-specific defense reactions through selective activation of the Toll and the immune deficiency (Imd) signaling pathways. The Toll pathway mediates most defenses against Gram-positive bacteria and fungi, whereas the Imd pathway is required to resist infection by Gram-negative bacteria. The bacterial components recognized by these pathways

François Leulier; Claudine Parquet; Sebastien Pili-Floury; Ji-Hwan Ryu; Martine Caroff; Won-Jae Lee; Dominique Mengin-Lecreulx; Bruno Lemaitre

2003-01-01

160

Turicibacter sanguinis gen. nov., sp. nov., a novel anaerobic, Gram-positive bacterium.  

PubMed

An unknown, strictly anaerobic, Gram-positive, rod-shaped bacterium (strain MOL361T) was isolated from a blood culture of a febrile patient with acute appendicitis and characterized using phenotypic and molecular methods. Fatty acid analysis and biochemical examination indicated that the isolate most closely resembles members of the Gram-positive bacteria with low DNA G+C content. 16S rDNA sequencing revealed a relatively high overall similarity (97%) to an uncultured bacterium, but these two strains both exhibit low (<87%) 16S rDNA similarity to other bacteria. Phylogenetic analysis with different treeing methods showed that this strain forms a novel line of descent within the Gram-positive bacteria with low G+C content. Strain MOL361T is described as the type strain of a novel species within a new genus, Turicibacter sanguinis gen. nov., sp. nov. PMID:12148638

Bosshard, Philipp P; Zbinden, Reinhard; Altwegg, Martin

2002-07-01

161

Why are rod-shaped bacteria rod shaped?  

Microsoft Academic Search

Generally speaking, bacteria grow and divide indefinitely, and as long as the growth conditions are maintained they retain constant dimensions and shapes with little variation. How they do this is a question that I have been considering for three decades. Here, I discuss two hypothetical mechanisms, one for Gram-positive rods and the other for Gram-negative rods. These mechanisms are consistent

Arthur L Koch

2002-01-01

162

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. PMID:21874075

Dykhuizen, Daniel

2010-01-01

163

Antibiotic-resistant bacteria in drinking water.  

PubMed Central

We analyzed drinking water from seven communities for multiply antibiotic-resistant (MAR) bacteria (bacteria resistant to two or more antibiotics) and screened the MAR bacterial isolates obtained against five antibiotics by replica plating. Overall, 33.9% of 2,653 standard plate count bacteria from treated drinking waters were MAR. Two different raw water supplies for two communities carried MAR standard plate count bacteria at frequencies of 20.4 and 18.6%, whereas 36.7 and 67.8% of the standard plate count populations from sites within the respective distribution systems were MAR. Isolate identification revealed that MAR gram-positive cocci (Staphylococcus) and MAR gram-negative, nonfermentative rods (Pseudomonas, Alcaligenes, Moraxella-like group M, and Acinetobacter) were more common in drinking waters than in untreated source waters. Site-to-site variations in generic types and differences in the incidences of MAR organisms indicated that shedding of MAR bacteria living in pipelines may have contributed to the MAR populations in tap water. We conclude that the treatment of raw water and its subsequent distribution select for standard plate count bacteria exhibiting the MAR phenotype. PMID:7283426

Armstrong, J L; Shigeno, D S; Calomiris, J J; Seidler, R J

1981-01-01

164

THE MITOCHONDRIA OF BACTERIA  

Microsoft Academic Search

Recent evidence from the biochemical, the genetic and the morphologic study of bacteria, in that chronological order, has indicated essential similarities of the bacterial cell to the cells of higher organisms. Recognition in bacteria of a large category of cytoplasmic granules as possessing characteristics which strongly sug- gest that they are the functional equivalents of the mitochondria of anirnaE and

STUART MUDD

1953-01-01

165

Screening for Inhibitory Activity of Essential Oils on Selected Bacteria, Fungi and Viruses  

Microsoft Academic Search

The purpose of this study was to examine the inhibitory effect of essential oils against a broad spectrum of microorganisms including bacteria, yeast, molds, and two bacteriophage. The inhibitory effects of 45 oils on eight bacteria (four Gram positive and four Gram negative), two fungi, and one yeast were examined using the disk assay method. Phage inhibition was measured by

Sue C. Chao; D. Gary Young; Craig J. Oberg

2000-01-01

166

Functional polypyrrole-silica composites as photothermal agents for targeted killing of bacteria.  

PubMed

We demonstrate for the first time that PPy-SiO2-GTA composites can be used as efficient photothermal agents for killing pathogenic bacteria under NIR irradiation. The cell growth of both gram-positive and gram-negative bacteria targeted by PPy-SiO2-GTA composites could be inhibited effectively after photothermal treatment. PMID:23985567

Ju, Enguo; Li, Zhenhua; Li, Meng; Dong, Kai; Ren, Jinsong; Qu, Xiaogang

2013-10-11

167

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

168

Differential detection of key enzymes of polyaromatic-hydrocarbon-degrading bacteria using PCR and gene probes  

Microsoft Academic Search

Bacteria with ability to degrade polyaromatic hydrocarbons (PAHs), isolated from wastewater and soil samples, were investigated for their taxonomic, physiological and genetic diversity. Eighteen isolates able to metabolize naphthalene or phenanthrene as sole carbon source were taxonomically affiliated to different subclasses of the Proteobacteria (Sphingomonas spp., Acidovorax spp., Comamonas spp. and Pseudomonas spp.) and to phyla of Gram-positive bacteria with

Svenja Meyer; Ralf Moser; Alexander Neef; U. Stahl; Peter Kampfer

1999-01-01

169

Efficacy of telavancin, a lipoglycopeptide antibiotic, in experimental models of Gram-positive infection.  

PubMed

Telavancin is a parenteral lipoglycopeptide antibiotic with a dual mechanism of action contributing to bactericidal activity against multidrug-resistant Gram-positive pathogens. It has been approved for the treatment of complicated skin and skin structure infections due to susceptible Gram-positive bacteria and hospital-acquired/ventilator-associated bacterial pneumonia due to Staphylococcus aureus when other alternatives are unsuitable. Telavancin has been demonstrated to be efficacious in multiple animal models of soft tissue, cardiac, systemic, lung, bone, brain and device-associated infections involving clinically relevant Gram-positive pathogens, including methicillin-resistant S. aureus, glycopeptide-intermediate S. aureus, heterogeneous vancomycin-intermediate S. aureus and daptomycin non-susceptible methicillin-resistant S. aureus. The AUC0-24h/MIC ratio is the primary pharmacodynamically-linked pharmacokinetic parameter. The preclinical data for telavancin supports further investigative clinical evaluation of its efficacy in additional serious infections caused by susceptible Gram-positive pathogens. PMID:25382700

Hegde, Sharath S; Janc, James W

2014-12-01

170

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. PMID:19231985

Nikaido, Hiroshi

2010-01-01

171

Bactericidal effects of antibiotics on slowly growing and nongrowing bacteria.  

PubMed Central

Antimicrobial agents are most often tested against bacteria in the log phase of multiplication to produce the maximum bactericidal effect. In an infection, bacteria may multiply less optimally. We examined the effects of several classes of antimicrobial agents to determine their actions on gram-positive and gram-negative bacteria during nongrowing and slowly growing phases. Only ciprofloxacin and ofloxacin exhibited bactericidal activity against nongrowing gram-negative bacteria, and no antibiotics were bactericidal (3-order-of-magnitude killing) against Staphylococcus aureus. For the very slowly growing gram-negative bacteria studied, gentamicin (an aminoglycoside), imipenem (a carbapenem), meropenem (a carbapenem), ciprofloxacin (a fluoroquinolone), and ofloxacin (a fluoroquinolone) exhibited up to 5.7 orders of magnitude more killing than piperacillin or cefotaxime. This is in contrast to optimally growing bacteria, in which a wide variety of antibiotic classes produced 99.9% killing. For the gram-positive and gram-negative bacteria we examined, antibiotic killing was greatly dependent on the growth rate. The clinical implications of slow killing by chemotherapeutic agents for established bacterial infections and infections involving foreign bodies are unknown. PMID:1952852

Eng, R H; Padberg, F T; Smith, S M; Tan, E N; Cherubin, C E

1991-01-01

172

Intercellular communication in bacteria.  

PubMed

Bacteria have been long considered primitive organisms, with a lifestyle focused on the survival and propagation of single cells. However, in the past few decades it became obvious that bacteria can display sophisticated group behaviors. For instance, bacteria can communicate amongst themselves and with their hosts, by producing, sensing, and responding to chemical signals. By doing so, they can sense their surroundings and adapt as to increase their chances of survival and propagation. Here, we review the discovery of bacterial intercellular communication, some of the signaling molecules identified to date, the role of intercellular signaling in symbiotic and pathogenic relationships between bacteria and their hosts and its implications for the development of new therapeutic strategies against human disease. PMID:19514909

Antunes, L Caetano M; Ferreira, Rosana B R

2009-01-01

173

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

174

Bacteria in shear flow  

E-print Network

Bacteria are ubiquitous and play a critical role in many contexts. Their environment is nearly always dynamic due to the prevalence of fluid flow: creeping flow in soil, highly sheared flow in bodily conduits, and turbulent ...

Marcos, Ph.D. Massachusetts Institute of Technology

2011-01-01

175

Postantibiotic Leukocyte Enhancement of Meropenem against Gram-Positive and Gram-Negative Strains  

Microsoft Academic Search

The pharmacodynamic aspects of antimicrobial drugs, such as the postantibiotic effect (PAE), have been extensively stud- ied in the last 15 years with gram-positive and gram-negative bacteria in order to analyze their possible influence on antibi- otic dosage regimens (3). Bacterial susceptibility to leukocyte phagocytosis and killing is usually enhanced when organisms are in the PAE phase (11, 12, 19,

ANDREA NOVELLI; STEFANIA FALLANI; MARIA IRIS CASSETTA; SILVIA CONTI; TERESITA MAZZEI

2000-01-01

176

Cell Size Control in Bacteria  

PubMed Central

Like eukaryotes, bacteria must coordinate division with growth to ensure cells are the appropriate size for a given environmental condition or developmental fate. As single-celled organisms, nutrient availability is one of the strongest influences on bacterial cell size. Classic physiological experiments conducted over four decades ago first demonstrated that cell size is directly correlated with nutrient source and growth rate in the Gram-negative bacterium Salmonella typhimurium. This observation subsequently served as the basis for studies revealing a role for cell size in cell cycle progression in a closely related organism, Escherichia coli. More recently, the development of powerful genetic, molecular, and imaging tools has allowed us to identify and characterize the nutrient-dependent pathway responsible for coordinating cell division and cell size with growth rate in the Gram-positive model organism B. subtilis. Here, we discuss the role of cell size in bacterial growth and development and propose a broadly applicable model for cell size control in this important and highly divergent domain of life. PMID:22575476

Chien, An-Chun; Hill, Norbert S.; Levin, Petra Anne

2012-01-01

177

Comparative genomic analysis of T-box regulatory systems in bacteria  

Microsoft Academic Search

T-box antitermination is one of the main mechanisms of regulation of genes involved in amino acid metabolism in Gram-positive bacteria. T-box regulatory sites consist of conserved sequence and RNA secondary structure elements. Using a set of known T- box sites, we constructed the common pattern and used it to scan available bacterial genomes. New T-boxes were found in various Gram-positive

ALEXEY G. VITRESCHAK; ANDREI A. MIRONOV; VASSILY A. LYUBETSKY; MIKHAIL S. GELFAND

2008-01-01

178

TSSWCB Bacteria-Related Projects  

E-print Network

of the projects are listed below. ? Peach CreekWater Quality Improvement Project ? Monitoring and Educational Programs Focused on Bacteria and Nutrient Runoff on Dairy Operations in the LeonWatershed ? Development of the Plum CreekWPP ? Impact of Proper... above Canyon Lake: A TMDL Project for Bacteria ? Houston Metropolitan Area: A TMDL Project for Bacteria ? Leon River below Proctor Lake ? Northwest Houston Area Bacteria TMDL Project ? Oso Bay and Oso Creek: A TMDL Project for Bacteria ? Peach...

Wythe, Kathy

2007-01-01

179

Systematics of Anoxygenic Phototrophic Bacteria  

Microsoft Academic Search

Many of the anoxygenic phototrophic bacteria, in particular green sulfur bacteria and purple sulfur bacteria are actively\\u000a involved in the dissimilatory sulfur cycle by oxidizing reduced sulfur compounds. An introduction to the current state of\\u000a the systematics of anoxygenic phototrophic bacteria is given here. With the introduction of 16S rDNA sequences, the consideration\\u000a of genetic relatedness of these bacteria and

Johannes F. Imhoff

180

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. PMID:22736894

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

2012-01-01

181

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. PMID:11148009

Brouqui, P.; Raoult, D.

2001-01-01

182

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. PMID:24516424

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

2013-01-01

183

Ice-Nucleating Bacteria  

NASA Astrophysics Data System (ADS)

Since the discovery of ice-nucleating bacteria in 1974 by Maki et al., a large number of studies on the biological characteristics, ice-nucleating substance, ice nucleation gene and frost damage etc. of the bacteria have been carried out. Ice-nucleating bacteria can cause the freezing of water at relatively warm temperature (-2.3°C). Tween 20 was good substrates for ice-nucleating activity of Pseudomonas fluorescens KUIN-1. Major fatty acids of Isolate (Pseudomonas fluorescens) W-11 grown at 30°C were palmitic, cis-9-hexadecenoic and cis-11-octadecenoic which amounted to 90% of the total fatty acids. Sequence analysis shows that an ice nucleation gene from Pseudomonas fluorescens is related to the gene of Pseudomonas syringae.

Obata, Hitoshi

184

Ecology and population dynamics of bacteria in foods  

E-print Network

of population attained varied with temperature of incubation, types of media, pH, the effector species tested and the initial ratio of effector to staphylococcus. With respect to causes of inhibition, the authors showed that S. marcescens and Pseudomonas... with the master plate. Plate count agar (PCA) was used for this plate. Replica plates were prepared on (a) Pseudomonas agar F to check for fluorescin production, (b) Olson's medium to check inhibition of gram-positive bacteria (27), (c) Staphylococcus medium...

Patel, Gordhanbhai Desaibhai

2012-06-07

185

Mineralization of Bacteria  

Microsoft Academic Search

A variety of viable and nonviable bacteria became mineralized with hydroxyapatite when implanted in dialysis bags in the peritoneal cavities of rats. The microscopic pattern of mineral deposition appeared analogous to that in the formation of oral calculus. Since nonviable organisms were mineralized at an accelerated rate, bacterial metabolic processes may not be essential for mineralization.

A. A. Rizzo; G. R. Martin; D. B. Scott; S. E. Mergenhagen

1962-01-01

186

Enteric bacteria mandibular osteomyelitis.  

PubMed

Osteomyelitis of the mandible is a relatively rare inflammatory disease that usually stems from the odontogenic polymicrobial flora of the oral cavity. We are reporting 2 unusual cases of mandibular osteomyelitis resulting from enteric bacteria infection. In one patient, abundant clinical evidence suggested a diagnosis of a chronic factitious disease, whereas in the second patient no obvious etiology was found. PMID:15897844

Scolozzi, Paolo; Lombardi, Tommaso; Edney, Timothy; Jaques, Bertrand

2005-06-01

187

Glowing Bacteria: Transformation Efficiency  

E-print Network

took up and expressed GFP after transformation. Background: Transformation efficiency is a quantitative1 Glowing Bacteria: Transformation Efficiency Purpose: To determine how well your E. coli cells. The number represents how many cells were transformed per microgram (µg) of plasmid DNA used

Rose, Michael R.

188

Aquatic Bacteria Samples  

USGS Multimedia Gallery

On April 20, 2010, the BP Deepwater Horizon drilling platform collapsed and sank in the Gulf of Mexico, causing one of the largest oil spills in history. One of the big dilemmas in responding to the oil spil is how to clean up the oil itself. One way currently under research is to use bacteria that ...

2010-06-14

189

Bacteria and phenoptosis.  

PubMed

Genetically programmed death of an organism, or phenoptosis, can be found not only in animals and plants, but also in bacteria. Taking into account intrapopulational relations identified in bacteria, it is easy to imagine the importance of phenoptosis in the regulation of a multicellular bacterial community in the real world of its existence. For example, autolysis of part of the population limits the spread of viral infection. Destruction of cells with damaged DNA contributes to the maintenance of low level of mutations. Phenoptosis can facilitate the exchange of genetic information in a bacterial population as a result of release of DNA from lysed cells. Bacteria use a special "language" to transmit signals in a population; it is used for coordinated regulation of gene expression. This special type of regulation of bacterial gene expression is usually active at high densities of bacteria populations, and it was named "quorum sensing" (QS). Different molecules can be used for signaling purposes. Phenoptosis, which is carried out by toxin-antitoxin systems, was found to depend on the density of the population; it requires a QS factor, which is called the extracellular death factor. The study of phenoptosis in bacteria is of great practical importance. The components that make up the systems ensuring the programmed cell death, including QS factor, may be used for the development of drugs that will activate mechanisms of phenoptosis and promote the destruction of pathogenic bacteria. Comparative genomic analysis revealed that the genes encoding several key enzymes involved in apoptosis of eukaryotes, such as paracaspases and metacaspases, apoptotic ATPases, proteins containing NACHT leucine-rich repeat, and proteases similar to mitochondrial HtrA-like protease, have homologs in bacteria. Proteomics techniques have allowed for the first time to identify the proteins formed during phenoptosis that participate in orderly liquidation of Streptomyces coelicolor and Escherichia coli cells. Among these proteins enzymes have been found that are involved in the degradation of cellular macromolecules, regulatory proteins, and stress-induced proteins. Future studies involving methods of biochemistry, genetics, genomics, proteomics, transcriptomics, and metabolomics should support a better understanding of the "mystery" of bacterial programmed cell death; this knowledge might be used to control bacterial populations. PMID:24228917

Koksharova, O A

2013-09-01

190

Lactic Acid Bacteria Inducing a Weak Interleukin12 and Tumor Necrosis Factor Alpha Response in Human Dendritic Cells Inhibit Strongly Stimulating Lactic Acid Bacteria but Act Synergistically with Gram-Negative Bacteria  

Microsoft Academic Search

The development and maintenance of immune homeostasis indispensably depend on signals from the gut flora. Lactic acid bacteria (LAB), which are gram-positive (G) organisms, are plausible significant players and have received much attention. Gram-negative (G) commensals, such as members of the family Entero- bacteriaceae, may, however, be immunomodulators that are as important as G organisms but tend to be overlooked.

Louise Hjerrild Zeuthen; Hanne Risager Christensen; H. Frokiaer

2006-01-01

191

Gram-Negative Bacteria Produce Membrane Vesicles Which Are Capable of Killing Other Bacteria  

PubMed Central

Naturally produced membrane vesicles (MVs), isolated from 15 strains of gram-negative bacteria (Citrobacter, Enterobacter, Escherichia, Klebsiella, Morganella, Proteus, Salmonella, and Shigella strains), lysed many gram-positive (including Mycobacterium) and gram-negative cultures. Peptidoglycan zymograms suggested that MVs contained peptidoglycan hydrolases, and electron microscopy revealed that the murein sacculi were digested, confirming a previous modus operandi (J. L. Kadurugamuwa and T. J. Beveridge, J. Bacteriol. 174:2767–2774, 1996). MV-sensitive bacteria possessed A1?, A4?, A1?, A2?, and A4? peptidoglycan chemotypes, whereas A3?, A3?, A3?, A4?, B1?, and B1? chemotypes were not affected. Pseudomonas aeruginosa PAO1 vesicles possessed the most lytic activity. PMID:9765585

Li, Zusheng; Clarke, Anthony J.; Beveridge, Terry J.

1998-01-01

192

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

193

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

194

Cell wall structure and function in lactic acid bacteria  

PubMed Central

The cell wall of Gram-positive bacteria is a complex assemblage of glycopolymers and proteins. It consists of a thick peptidoglycan sacculus that surrounds the cytoplasmic membrane and that is decorated with teichoic acids, polysaccharides, and proteins. It plays a major role in bacterial physiology since it maintains cell shape and integrity during growth and division; in addition, it acts as the interface between the bacterium and its environment. Lactic acid bacteria (LAB) are traditionally and widely used to ferment food, and they are also the subject of more and more research because of their potential health-related benefits. It is now recognized that understanding the composition, structure, and properties of LAB cell walls is a crucial part of developing technological and health applications using these bacteria. In this review, we examine the different components of the Gram-positive cell wall: peptidoglycan, teichoic acids, polysaccharides, and proteins. We present recent findings regarding the structure and function of these complex compounds, results that have emerged thanks to the tandem development of structural analysis and whole genome sequencing. Although general structures and biosynthesis pathways are conserved among Gram-positive bacteria, studies have revealed that LAB cell walls demonstrate unique properties; these studies have yielded some notable, fundamental, and novel findings. Given the potential of this research to contribute to future applied strategies, in our discussion of the role played by cell wall components in LAB physiology, we pay special attention to the mechanisms controlling bacterial autolysis, bacterial sensitivity to bacteriophages and the mechanisms underlying interactions between probiotic bacteria and their hosts. PMID:25186919

2014-01-01

195

Endocarditis due to Anaerobic Bacteria  

Microsoft Academic Search

This review describes the microbiology, diagnosis and management of endocarditis due to anaerobic bacteria. Anaerobic bacteria are an uncommon but important cause of endocarditis. Most cases of anaerobic endocarditis are caused by anaerobic cocci, Propionibacterium acnes and Bacteroides fragilis group. Predisposing factors and signs and symptoms of endocarditis caused by anaerobic bacteria are similar to those seen in endocarditis with

Itzhak Brook

2002-01-01

196

Denitrification by extremely halophilic bacteria  

NASA Technical Reports Server (NTRS)

Extremely halophilic bacteria were isolated from widely separated sites by anaerobic enrichment in the presence of nitrate. The anaerobic growth of several of these isolates was accompanied by the production of nitrite, nitrous oxide, and dinitrogen. These results are a direct confirmation of the existence of extremely halophilic denitrifying bacteria, and suggest that such bacteria may be common inhabitants of hypersaline environments.

Hochstein, L. I.; Tomlinson, G. A.

1985-01-01

197

Genomics of cellulolytic bacteria.  

PubMed

The heterogeneous plant biomass is efficiently decomposed by the interplay of a great number of different enzymes. The enzyme systems in cellulolytic bacteria have been investigated by sequencing and bioinformatic analysis of genomes from plant biomass degrading microorganisms with valuable insights into the variety of the involved enzymes. This broadened our understanding of the biochemical mechanisms of plant polymer degradation and made the enzymes applicable for modern biotechnology. A list of the truly cellulolytic bacteria described and the available genomic information was examined for proteins with cellulolytic and hemicellulolytic capability. The importance of the isolation, characterization and genomic sequencing of cellulolytic microorganisms and their usage for sustainable energy production from biomass and other residues, is emphasized. PMID:25104562

Koeck, Daniela E; Pechtl, Alexander; Zverlov, Vladimir V; Schwarz, Wolfgang H

2014-10-01

198

[Natural transformation in bacteria].  

PubMed

Transformants may be formed by some bacterial species when the growing cultures are mixed. This phenomenon caused by the DNA release from bacterial cells is called natural transformation. DNA release is most likely to be mediated by cell autolysis. Both chromosomal markers and plasmids are transferred by natural transformation. The phenomenon is reproduced while growing bacteria together in sterile soil. The DNA adsorbed on sand and other soil solid particles was more resistant to DNAse action, than the free transforming DNA. Natural transformation seems to be one of the forms of the genetic exchange in bacteria in their habitats. An indirect argument for this suggestion is perfect coordination between the different steps of transformation process, at least, in some bacterial species. PMID:2185417

Kosovich, P V; Prozorov, A A

1990-01-01

199

Exopolysaccharides from marine bacteria  

NASA Astrophysics Data System (ADS)

Microbial polysaccharides represent a class of important products of growing interest for many sectors of industry. In recent years, there has been a growing interest in isolating new exopolysaccharides (EPSs)-producing bacteria from marine environments, particularly from various extreme marine environments. Many new marine microbial EPSs with novel chemical compositions, properties and structures have been found to have potential applications in fields such as adhesives, textiles, Pharmaceuticals and medicine for anti-cancer, food additives, oil recovery and metal removal in mining and industrial waste treatments, etc This paper gives a brief summary of the information about the EPSs produced by marine bacteria, including their chemical compositions, properties and structures, together with their potential applications in industry.

Chi, Zhenming; Fang, Yan

2005-01-01

200

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.

201

Reanimation of Ancient Bacteria  

SciTech Connect

Recent highly publicized experiments conducted on salt crystals taken from the Permian Salado Formation in Southeastern New Mexico have shown that some ancient crystals contain viable microorganisms trapped within fluid inclusions. Stringent geological and microbiological selection criteria were used to select crystals and conduct all sampling. This talk will focus on how each of these lines of data support the conclusion that such isolated bacteria are as old as the rock in which they are trapped. In this case, the isolated microbes are salt tolerant bacilli that grow best in media containing 8% NaCl, and respond to concentrated brines by forming spores. One of the organisms is phylogenetically related to several bacilli, but does have several unique characteristics. This talk will trace the interdisciplinary data and procedures supporting these discoveries, and describe the various isolated bacteria.

Russell Vreeland

2009-01-09

202

Bacteria, food, and cancer  

PubMed Central

Gut microbes are essential components of the human organism—helping us metabolize food into energy, produce micronutrients, and shape our immune systems. Having a particular pattern of gut microbes is also increasingly being linked to medical conditions including obesity, inflammatory bowel disease, and diabetes. Recent studies now indicate that our resident intestinal bacteria may also play a critical role in determining one's risk of developing cancer, ranging from protection against cancer to promoting its initiation and progression. Gut bacteria are greatly influenced by diet and in this review we explore evidence that they may be the missing piece that explains how dietary intake influences cancer risk, and discuss possible prevention and treatment strategies. PMID:21876723

Rooks, Michelle G.

2011-01-01

203

Characterization of viable bacteria from Siberian permafrost by 16S rDNA sequencing  

NASA Technical Reports Server (NTRS)

Viable bacteria were found in permafrost core samples from the Kolyma-Indigirka lowland of northeast Siberia. The samples were obtained at different depths; the deepest was about 3 million years old. The average temperature of the permafrost is -10 degrees C. Twenty-nine bacterial isolates were characterized by 16S rDNA sequencing and phylogenetic analysis, cell morphology, Gram staining, endospore formation, and growth at 30 degrees C. The majority of the bacterial isolates were rod shaped and grew well at 30 degrees C; but two of them did not grow at or above 28 degrees C, and had optimum growth temperatures around 20 degrees C. Thirty percent of the isolates could form endospores. Phylogenetic analysis revealed that the isolates fell into four categories: high-GC Gram-positive bacteria, beta-proteobacteria, gamma-proteobacteria, and low-GC Gram-positive bacteria. Most high-GC Gram-positive bacteria and beta-proteobacteria, and all gamma-proteobacteria, came from samples with an estimated age of 1.8-3.0 million years (Olyor suite). Most low-GC Gram-positive bacteria came from samples with an estimated age of 5,000-8,000 years (Alas suite).

Shi, T.; Reeves, R. H.; Gilichinsky, D. A.; Friedmann, E. I.

1997-01-01

204

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

205

Adaptive mutability in bacteria  

Microsoft Academic Search

Reactive oxygen species (ROS) are a common source of damage to cellular DNA, and have been implicated in mutagenesis and carcinogenesis.\\u000a In bacteria, their mutagenicity appears to be mediated in part by the mutagenic SOS system and in part by SOS-independent\\u000a mechanisms. Since acrobically growing log-phase cells (which by definition are well adapted to their environment) would not\\u000a be especially

Donald G. Macphee

1999-01-01

206

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

2010-03-01

207

Identification, classification, and clinical relevance of catalase-negative, gram-positive cocci, excluding the streptococci and enterococci.  

PubMed Central

Several new genera and species of gram-positive, catalase-negative cocci that can cause infections in humans have been described. Although these bacteria were isolated in the clinical laboratory, they were considered nonpathogenic culture contaminants and were not thought to be the cause of any diseases. Isolation of pure cultures of these bacteria from normally sterile sites has led to the conclusion that these bacteria can be an infrequent cause of infection. This review describes the new bacteria and the procedures useful for clinical laboratories to aid in their identification. The clinical relevance and our experience with the various genera and species are reviewed and discussed. PMID:8665466

Facklam, R; Elliott, J A

1995-01-01

208

Living bacteria in silica gels  

NASA Astrophysics Data System (ADS)

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 is a real challenge for the development of sol-gel processes. Generic tests have been performed to check the viability of Escherichia coli bacteria in silica gels. Surprisingly, more bacteria remain culturable in the gel than in an aqueous suspension. The metabolic activity of the bacteria towards glycolysis decreases slowly, but half of the bacteria are still viable after one month. When confined within a mineral environment, bacteria do not form colonies. The exchange of chemical signals between isolated bacteria rather than aggregates can then be studied, a point that could be very important for 'quorum sensing'.

Nassif, Nadine; Bouvet, Odile; Noelle Rager, Marie; Roux, Cécile; Coradin, Thibaud; Livage, Jacques

2002-09-01

209

Phenotypic and Phylogenetic Characterization of Ruminal Tannin-Tolerant Bacteria  

PubMed Central

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, Karen E.; Thonney, Michael L.; Woolston, Tina K.; Zinder, Stephen H.; Pell, Alice N.

1998-01-01

210

Bacteria in the Cafeteria  

NSDL National Science Digital Library

This activity from the American Museum of Natural History's family magazine series challenges kids to go on a microbe quest to solve a riddle. The online activity begins with a page of directions for how to find the missing letters of the riddle. As kids click their way around a virtual lunchroom, they are given 11 Yes/No questions asking whether the featured bacteria helps people. Along with the answer to the riddle, kids get a round of applause when they correctly answer all 11 questions.

211

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 PMID:1723487

Beveridge, T J; Graham, L L

1991-01-01

212

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

213

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

214

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

215

Comparative In Vitro Activities of Torezolid (DA-7157) against Clinical Isolates of Aerobic and Anaerobic Bacteria in South Korea ?  

PubMed Central

Resistance of Gram-positive pathogens to first-line antimicrobial agents has been increasing in many parts of the world. We compared the in vitro activities of torezolid with those of other antimicrobial agents, including linezolid, against clinical isolates of major aerobic and anaerobic bacteria. Torezolid had an MIC90 of ?0.5 ?g/ml for the Gram-positive bacterial isolates tested and was more potent than either linezolid or vancomycin. PMID:20837761

Yum, Jong Hwa; Choi, Sung Hak; Yong, Dongeun; Chong, Yunsop; Im, Weon Bin; Rhee, Dong-Kwon; Lee, Kyungwon

2010-01-01

216

Nitrogen control in bacteria.  

PubMed Central

Nitrogen metabolism in prokaryotes involves the coordinated expression of a large number of enzymes concerned with both utilization of extracellular nitrogen sources and intracellular biosynthesis of nitrogen-containing compounds. The control of this expression is determined by the availability of fixed nitrogen to the cell and is effected by complex regulatory networks involving regulation at both the transcriptional and posttranslational levels. While the most detailed studies to date have been carried out with enteric bacteria, there is a considerable body of evidence to show that the nitrogen regulation (ntr) systems described in the enterics extend to many other genera. Furthermore, as the range of bacteria in which the phenomenon of nitrogen control is examined is being extended, new regulatory mechanisms are also being discovered. In this review, we have attempted to summarize recent research in prokaryotic nitrogen control; to show the ubiquity of the ntr system, at least in gram-negative organisms; and to identify those areas and groups of organisms about which there is much still to learn. PMID:8531888

Merrick, M J; Edwards, R A

1995-01-01

217

Can entropy save bacteria?  

E-print Network

This article presents a physical biology approach to understanding organization and segregation of bacterial chromosomes. The author uses a "piston" analogy for bacterial chromosomes in a cell, which leads to a phase diagram for the organization of two athermal chains confined in a closed geometry characterized by two length scales (length and width). When applied to rod-shaped bacteria such as Escherichia coli, this phase diagram predicts that, despite strong confinement, duplicated chromosomes will demix, i.e., there exists a primordial physical driving force for chromosome segregation. The author discusses segregation of duplicating chromosomes using the concentric-shell model, which predicts that newly synthesized DNA will be found in the periphery of the chromosome during replication. In contrast to chromosomes, these results suggest that most plasmids will be randomly distributed inside the cell because of their small sizes. An active partitioning system is therefore required for accurate segregation of low-copy number plasmids. Implications of these results are also sketched, e.g., on the role of proteins, segregation mechanisms for bacteria of diverse shapes, cell cycle of an artificial cell, and evolution.

Suckjoon Jun

2008-08-19

218

Correlation between Major Constituents and Antibacterial Activities of Some Plant Essential Oils against Some Pathogenic Bacteria  

Microsoft Academic Search

Five different plant essential oils (Satureja hortensis, Thymus sipyleus ssp. rosulans, Thymus haussknechtii, Origanum rotundifolium (cultured form) and Origanum acutidens (wild and cultured form)) and their two major constituents carvacarol and thymol were evaluated for antibacterial activity against food-borne Gram negative (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella enteritidis) and Gram positive bacteria (Bacillus subtilis, Streptococcus pyogenes and Enterococcus

Neslihan Dikbas; Recep Kotan; Fatih Dadasoglu; Kenan Karagöz; Ramazan Çakmakci

219

Simultaneous Fluorescent Gram Staining and Activity Assessment of Activated Sludge Bacteria  

Microsoft Academic Search

Wastewater treatment is one of the most important commercial biotechnological processes, and yet the component bacterial populations and their associated metabolic activities are poorly understood. The novel fluorescent dye hexidium iodide allows assessment of Gram status by differential absorption through bacterial cell walls. Differentiation between gram-positive and gram-negative wastewater bacteria was achieved after flow cytometric analysis. This study shows that

Scott Forster; Jason R. Snape; Hilary M. Lappin-Scott; Jonathan Porter

2002-01-01

220

RELATIONSHIP OF RUMEN GRAM-NEGATIVE BACTERIA AND FREE ENDOTOXIN TO LACTIC ACIDOSIS IN CATTLE x  

Microsoft Academic Search

SUMMARY Feeding grain to animals not adapted to grain resulted in a marked increase in the .\\/ . concentration of free endotoxln m the rumen. Endotoxin concentration increased 15 to 18 times within 12 hr after lactic acidosis was induced through grain engorgement. The increase was accompanied by a shift from predominantly gram-negative to gram-positive bacteria. Data from in vitro

T. G. Nagaraja; E. E. Bartley; L. R. Fina; H. D. Anthony

2010-01-01

221

Methanobactin: a copper binding compound having antibiotic and antioxidant activity isolated from methanotrophic bacteria  

DOEpatents

A means and method for treating bacterial infection, providing antioxidant activity, and chelating copper using a copper binding compound produced by methanotrophic bacteria is described. The compound, known as methanobactin, is the first of a new class of antibiotics having gram-positive activity. Methanobactin has been sequenced, and its structural formula determined.

DiSpirito, Alan A. (Ames, IA); Zahn, James A. (Harbor Beach, MI); Graham, David W. (Lawrence, KS); Kim, Hyung J. (St. Paul, MN); Alterman, Michail (Lawrence, KS); Larive, Cynthia (Lawrence, KS)

2007-04-03

222

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

223

Biological counterstrike: antibiotic resistance mechanisms of Gram-positive cocci.  

PubMed

The development of antibiotic resistance by bacteria is an evolutionary inevitability, a convincing demonstration of their ability to adapt to adverse environmental conditions. Since the emergence of penicillinase-producing Staphylococcus aureus in the 1940s, staphylococci, enterococci and streptococci have proved themselves adept at developing or acquiring mechanisms that confer resistance to all clinically available antibacterial classes. The increasing problems of methicillin-resistant S. aureus and coagulase-negative staphylococci (MRSA and MRCoNS), glycopeptide-resistant enterococci and penicillin-resistant pneumococci in the 1980s, and recognition of glycopeptide-intermediate S. aureus in the 1990s and, most recently, of fully vancomycin-resistant isolates of S. aureus have emphasised our need for new anti-Gram-positive agents. Antibiotic resistance is one of the major public health concerns for the beginning of the 21st century. The pharmaceutical industry has responded with the development of oxazolidinones, lipopeptides, injectable streptogramins, ketolides, glycylcyclines, second-generation glycopeptides and novel fluoroquinolones. However, clinical use of these novel agents will cause new selective pressures and will continue to drive the development of resistance. This review describes the various antibiotic resistance mechanisms identified in isolates of staphylococci, enterococci and streptococci, including mechanisms of resistance to recently introduced anti-Gram-positive agents. PMID:15811020

Woodford, N

2005-05-01

224

In vitro antimicrobial activity of GAR936 tested against antibiotic-resistant gram-positive blood stream infection isolates and strains producing extended-spectrum ?-lactamases  

Microsoft Academic Search

GAR-936, a new, semisynthetic glycylcycline, has shown good antibacterial activity against a wide range of clinically important Gram-positive and –negative aerobic bacteria including Streptococcus pneumoniae,Hemophilus influenzae,Moraxella catarrhalis,Neisseria gonorrhoeae, most Enterobacteriaceae, Staphylococcus aureus and Enterococcus spp. The purpose of this study was to determine the activity of GAR-936 against a range of Gram-positive and –negative bloodstream isolates including many strains producing

Douglas J Biedenbach; Mondell L Beach; Ronald N Jones

2001-01-01

225

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. PMID:24832653

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

2013-01-01

226

Aerobic salivary bacteria in wild and captive Komodo dragons.  

PubMed

During the months of November 1996, August 1997, and March 1998, saliva and plasma samples were collected for isolation of aerobic bacteria from 26 wild and 13 captive Komodo dragons (Varanus komodoensis). Twenty-eight Gram-negative and 29 Gram-positive species of bacteria were isolated from the saliva of the 39 Komodo dragons. A greater number of wild than captive dragons were positive for both Gram-negative and Gram-positive bacteria. The average number of bacterial species within the saliva of wild dragons was 46% greater than for captive dragons. While Escherichia coli was the most common bacterium isolated from the saliva of wild dragons, this species was not present in captive dragons. The most common bacteria isolated from the saliva of captive dragons were Staphylococcus capitis and Staphylococcus capitis and Staphylococcus caseolyticus, neither of which were found in wild dragons. High mortality was seen among mice injected with saliva from wild dragons and the only bacterium isolated from the blood of dying mice was Pasteurella multocida. A competitive inhibition enzyme-linked immunosorbent assay revealed the presence of anti-Pasteurella antibody in the plasma of Komodo dragons. Four species of bacteria isolated from dragon saliva showed resistance to one or more of 16 antimicrobics tested. The wide variety of bacteria demonstrated in the saliva of the Komodo dragon in this study, at least one species of which was highly lethal in mice and 54 species of which are known pathogens, support the observation that wounds inflicted by this animal are often associated with sepsis and subsequent bacteremia in prey animals. PMID:12238371

Montgomery, Joel M; Gillespie, Don; Sastrawan, Putra; Fredeking, Terry M; Stewart, George L

2002-07-01

227

Iron storage in bacteria.  

PubMed

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 haem-containing bacterioferritins and the haem-free ferritins. These proteins are widespread in bacteria, with at least 39 examples known so far in eubacteria and archaebacteria. The bacterioferritins and ferritins are distantly related but retain similar structural and functional properties. Both are composed of 24 identical or similar subunits (approximately 19 kDa) that form a roughly spherical protein (approximately 450 kDa, approximately 120 A diameter) containing a large hollow centre (approximately 80 A diameter). The hollow centre acts as an iron-storage cavity with the capacity to accommodate at least 2000 iron atoms in the form of a ferric-hydroxyphosphate core. Each subunit contains a four-helix bundle which carries the active site or ferroxidase centre of the protein. The ferroxidase centres endow ferrous-iron-oxidizing activity and are able to form a di-iron species that is an intermediate in the iron uptake, oxidation and core formation process. Bacterioferritins contain up to 12 protoporphyrin IX haem groups located at the two-fold interfaces between pairs of two-fold related subunits. The role of the haem is unknown, although it may be involved in mediating iron-core reduction and iron release. Some bacterioferritins are composed of two subunit types, one conferring haem-binding ability (alpha) and the other (beta) bestowing ferroxidase activity. Bacterioferritin genes are often adjacent to genes encoding a small [2Fe-2S]-ferredoxin (bacterioferritin-associated ferredoxin or Bfd). Bfd may directly interact with bacterioferritin and could be involved in releasing iron from (or delivering iron to) bacterioferritin or other iron complexes. Some bacteria contain two bacterioferritin subunits, or two ferritin subunits, that in most cases co-assemble. Others possess both a bacterioferritin and a ferritin, while some appear to lack any type of iron-storage protein. The reason for these differences is not understood. Studies on ferritin mutants have shown that ferritin enhances growth during iron starvation and is also involved in iron accumulation in the stationary phase of growth. The ferritin of Campylobacter jejuni is involved in redox stress resistance, although this does not appear to be the case for Escherichia coli ferritin (FtnA). No phenotype has been determined for E. coli bacterioferritin mutants and the precise role of bacterioferritin in E. coli remains uncertain. PMID:9889981

Andrews, S C

1998-01-01

228

Phenotypic switching in bacteria  

NASA Astrophysics Data System (ADS)

Living matter is a non-equilibrium system in which many components work in parallel to perpetuate themselves through a fluctuating environment. Physiological states or functionalities revealed by a particular environment are called phenotypes. Transitions between phenotypes may occur either spontaneously or via interaction with the environment. Even in the same environment, genetically identical bacteria can exhibit different phenotypes of a continuous or discrete nature. In this thesis, we pursued three lines of investigation into discrete phenotypic heterogeneity in bacterial populations: the quantitative characterization of the so-called bacterial persistence, a theoretical model of phenotypic switching based on those measurements, and the design of artificial genetic networks which implement this model. Persistence is the phenotype of a subpopulation of bacteria with a reduced sensitivity to antibiotics. We developed a microfluidic apparatus, which allowed us to monitor the growth rates of individual cells while applying repeated cycles of antibiotic treatments. We were able to identify distinct phenotypes (normal and persistent) and characterize the stochastic transitions between them. We also found that phenotypic heterogeneity was present prior to any environmental cue such as antibiotic exposure. Motivated by the experiments with persisters, we formulated a theoretical model describing the dynamic behavior of several discrete phenotypes in a periodically varying environment. This theoretical framework allowed us to quantitatively predict the fitness of dynamic populations and to compare survival strategies according to environmental time-symmetries. These calculations suggested that persistence is a strategy used by bacterial populations to adapt to fluctuating environments. Knowledge of the phenotypic transition rates for persistence may provide statistical information about the typical environments of bacteria. We also describe a design of artificial genetic networks that would implement a more general theoretical model of phenotypic switching. We will use a new cloning strategy in order to systematically assemble a large number of genetic features, such as site-specific recombination components from the R64 plasmid, which invert several coexisting DNA segments. The inversion of these segments would lead to discrete phenotypic transitions inside a living cell. These artificial phenotypic switches can be controlled precisely in experiments and may serve as a benchmark for their natural counterparts.

Merrin, Jack

229

STUDIES ON LUMINOUS BACTERIA  

PubMed Central

1. A method has been described whereby the intensity of the light of luminous bacteria may be measured in a quantitative manner. 2. It is pointed out that the temperature coefficients for light intensity do not follow the van't Hoff rule, but are higher and vary with each 10° temperature interval. 3. From a comparison with other data it is found that the process is not a simple one, but that the observed curve is the resultant of several reactions which proceed simultaneously. 4. The discrepancies in the temperature coefficients in the neighborhood of the "optimum temperature" may be due to a process of coagulation of the colloidal particles of the enzyme. This coagulation will tend to cause a deviation of the curve away from that normal for chemical reactions. PMID:19872179

Morrison, Thomas F.

1925-01-01

230

Bacteriophages of methanotrophic bacteria  

SciTech Connect

Bacteriophages of methanotrophic bacteria have been found in 16 out of 88 studied samples (underground waters, pond water, soil, gas and oil installation waters, fermentor cultural fluids, bacterial paste, and rumen of cattle) taken in different geographic zones of the Soviet Union. Altogether, 23 phage strains were isolated. By fine structure, the phages were divided into two types (with very short or long noncontractile tails); by host range and serological properties, they fell into three types. All phages had guanine- and cytosine-rich double-stranded deoxyribonucleic acid consisting of common nitrogen bases. By all of the above-mentioned properties, all phages within each of the groups were completely identical to one another, but differed from phages of other groups.

Tyutikow, F.M. (All-Union Research Inst. for Genetics and Selection of Industrial Microorganisms, Moscow, USSR); Bespalova, I.A.; Rebentish, B.A.; Aleksandrushkina, N.N.; Krivisky, A.S.

1980-10-01

231

Drug resistant bacteria in non carbonated mineral waters.  

PubMed

The presence of antibiotic resistant bacteria was revealed among bacteria isolated from non carbonated mineral waters bottled in plastic (PVC) and in glass containers. Heterotrophic plate count values ranged between < 10 and 4.3 x 10(3) and between < 10 and 1.2 x 10(4) colony forming units/ml for the waters bottled in PVC and glass, respectively. The greatest resistance to a single antibiotic, 39.1% of 320 isolates from mineral waters, was found for nalidixic acid. Resistance to the other antibiotics was as follows: ampicillin (26.2%), bacitracin (19.7%), cotrimoxazole (18.7%), streptomycin (15.0%), tetracycline (14.4%), gentamycin (11.6%), chloramphenicol and rifampin (9.7%). The strains resistant to two or more antibiotics (multiple antibiotic resistant, MAR) provided 51% of the total isolates. Identification of 127 MAR strains showed that in the mineral waters gram-positive cocci dominated. The second, third and fourth group of identified MAR phenotypes were, in order to importance, gram-negative non-fermentative rods, gram-positive rods and gram-negative fermentative rods. The importance of the antibiotic resistant bacteria in mineral water is discussed. PMID:8564367

Massa, S; Petruccioli, M; Fanelli, M; Gori, L

1995-11-01

232

Clay-Bacteria Systems and Biofilm Production  

NASA Astrophysics Data System (ADS)

Soil clots and the aerosol transport of bacteria and spores are promoted by the formation of biofilms (bacteria cells in an extracellular polymeric matrix). Biofilms protect microorganisms by promoting adhesion to both organic and inorganic surfaces. Time series experiments on bacteria-clay suspensions demonstrate that biofilm growth is catalyzed by the presence of hectorite in minimal growth media for the studied species: Gram negatives (Pseudomonas syringae and Escherichia coli,) and Gram positives (Staphylococcus aureus and Bacillus subtilis). Soil organisms (P. syringae, B. subtilis) and organisms found in the human population (E. coli, S. aureus) are both used to demonstrate the general applicability of clay involvement. Fluorescent images of the biofilms are acquired by staining with propidium iodide, a component of the BacLightTM Live/Dead bacterial viability staining kit (Molecular Probes, Eugene, OR). The evolving polysaccharide-rich biofilm reacts with the clay interlayer site causing a complex substitution of the two-water hectorite interlayer with polysaccharide. The result is often a three-peak composite of the (001) x-ray diffraction maxima resulting from polysaccharide-expanded clays and an organic-driven contraction of a subset of the clays in the reaction medium. X-ray diffractograms reveal that the expanded set creates a broad maximum with clay subsets at 1.84 nm and 1.41 nm interlayer spacings as approximated by a least squares double Lorentzian fit, and a smaller shoulder at larger 2q, deriving from a contraction of the interlayer spacing. Washing with chlorox removes organic material from the contracted clay and creates a 1-water hectorite single peak in place of the double peak. The clay response can be used as an indirect indicator of biofilm in an environmental system.

Steiner, J.; Alimova, A.; Katz, A.; Steiner, N.; Rudolph, E.; Gottlieb, P.

2007-12-01

233

Activities of the Semisynthetic Glycopeptide LY191145 against Vancomycin-Resistant Enterococci and Other Gram-Positive Bacteria  

Microsoft Academic Search

LY191145 is the prototype of a series of compounds with activities against vancomycin-resistant enterococci derived by modification of the glycopeptide antibiotic LY264826. LY191145 had MICs for vancomycin- and teicoplanin-resistant enterococci of <4 mg\\/ml for 50% of isolates and <16 mg\\/ml for 90% of isolates. Its MICs for vancomycin-resistant, teicoplanin-susceptible enterococci were 1 to 8 mg\\/ml. LY191145 retains the potent activities

THALIA I. NICAS; DEBORAH L. MULLEN; JANE E. FLOKOWITSCH; DAVID A. PRESTON; NANCY J. SNYDER; ROBERT E. STRATFORD; ANDROBIN D. G. COOPER

1995-01-01

234

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

PubMed

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). PMID:22721352

Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Le Coustumer, Phillippe; Constantin, Liliana Violeta; Predoi, Daniela

2012-01-01

235

New Vector for Efficient Allelic Replacement in Naturally Nontransformable, Low-GC-Content, Gram-Positive Bacteria  

Microsoft Academic Search

The study of chromosomal genes and the modification of bacterial strains require the development of new strategies and new genetic tools to facilitate the rapid screening of recombi- nant clones. Molecular genetic analyses require the exchange by homologous recombination of a chromosomal gene by a mutated allele or inactivated copy, and several strategies have been developed for generating gene replacements

Maryvonne Arnaud; Arnaud Chastanet; Michel Debarbouille

2004-01-01

236

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

NASA Astrophysics Data System (ADS)

Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10- x Ag x (PO4)6(OH)2, x Ag = 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 x Ag = 0.05, a = b = 9.443 Å, c = 6.875 Å for x Ag = 0.2, and a = b = 9.445 Å, c = 6.877 Å for x Ag = 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 ( x Ag = 0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of x Ag in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth ( P. stuartii).

Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Le Coustumer, Phillippe; Constantin, Liliana Violeta; Predoi, Daniela

2012-06-01

237

Synthesis and minimum inhibitory concentrations of SK03-92 against Staphylococcus aureus and other gram-positive bacteria  

Microsoft Academic Search

Staphylococcus aureus causes hundreds of thousands of infections and thousands of deaths per year in the United States. The emergence of methicillin-resistant\\u000a S. aureus (MRSA), including community-associated methicillin-resistant S. aureus (CA-MRSA), has added to the problem. As MRSA continue to evolve, they are becoming resistant to more classes of antibiotics.\\u000a In the past 20 years, only three new antibiotics have

William R. SchwanM; M. Shahjahan Kabir; Maren Kallaus; Sarah Krueger; Aaron Monte; James M. Cook

238

Restart of DNA replication in Gram-positive bacteria: functional characterisation of the Bacillus subtilis PriA initiator  

Microsoft Academic Search

The PriA protein was identified in Escherichia coli as a factor involved in the replication of extrachromo- somal elements such as bacteriophage ?X174 and plasmid pBR322. Recent data show that PriA plays an important role in chromosomal replication, by promoting reassembly of the replication machinery during reinitiation of inactivated forks. A gene encoding a product 32% identical to the E.coli

Patrice Polard; Stéphanie Marsin; Stephen McGovern; Marion Velten; Dale B. Wigley; S. Dusko; Claude Bruand

239

Target Affinities of Faropenem to and Its Impact on the Morphology of Gram-Positive and Gram-Negative Bacteria  

Microsoft Academic Search

Faropenem is a new oral ?-lactam antibiotic unique from carbapenems and other available ?-lactams. Determinants of the in vitro activity of ?-lactam antibiotics include affinity to penicillin-binding proteins (PBPs) and ?-lactamase stability. In this study, the binding affinity of faropenem to various PBPs and its impact on the morphology of Staphylococcus aureus and Escherichia coli were evaluated. In general, faropenem

A. Dalhoff; T. Nasu; K. Okamoto

2003-01-01

240

Bacteria belonging to the genus Oceanobacillus are Gram-positive, aerobic, motile, rod-shaped, and spore-forming (Yumoto  

E-print Network

extract, 0.1 g ferric citrate, 19.45 g sodium chloride, 5.9 g magnesium chloride, 3.24 g magnesium sulfate, 1.8 g calcium chloride, 0.55 g potassium chloride, 0.16 g sodium bicarbonate, 0.08 g potassium bromide, 34 mg strontium chloride, 22 mg boric acid, 4 mg sodium silicate, 2.4 mg sodium fluoride, 1.6 mg

Bae, Jin-Woo

241

The ESAT-6 gene cluster of Mycobacterium tuberculosis and other high G+C Gram-positive bacteria  

Microsoft Academic Search

BACKGROUND: The genome of Mycobacterium tuberculosis H37Rv has five copies of a cluster of genes known as the ESAT-6 loci. These clusters contain members of the CFP-10 (lhp) and ESAT-6 (esat-6) gene families (encoding secreted T-cell antigens that lack detectable secretion signals) as well as genes encoding secreted, cell-wall-associated subtilisin-like serine proteases, putative ABC transporters, ATP-binding proteins and other membrane-associated

Nico C Gey van Pittius; Junaid Gamieldien; Winston Hide; Gordon D Brown; Roland J Siezen; Albert D Beyers

2001-01-01

242

Minimum inhibitory concentrations of herbal essential oils and monolaurin for gram-positive and gram-negative bacteria  

Microsoft Academic Search

New, safe antimicrobial agents are needed to prevent and overcome severe bacterial, viral, and fungal infections. Based on our previous experience and that of others, we postulated that herbal essential oils, such as those of origanum, and monolaurin offer such possibilities. We examined in vitro the cidal and\\/or static effects of oil of origanum, several other essential oils, and monolaurin

Harry G. Preuss; Bobby Echard; Mary Enig; Itzhak Brook; Thomas B. Elliott

2005-01-01

243

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). PMID:22721352

2012-01-01

244

Wolbachia Bacteria of Filarial Nematodes  

Microsoft Academic Search

The finding that the intracellular bacteria of filarial nematodes are related to the Wolbachia symbionts of arthropods has generated great interest. Here, Mark Taylor and Achim Hoerauf review recent studies by several groups on the structure, distribution and phylogeny of these endosymbionts, and discuss the potential role for these bacteria in filarial disease and as a target for chemotherapy.

M. J Taylor; A Hoerauf

1999-01-01

245

Periodontitis, periodontopathic bacteria and lactoferrin  

Microsoft Academic Search

Lactoferrin (LF) is a component of saliva and is suspected to be a defense factor against oral pathogens including Streptococcus mutans and Candida albicans. Periodontitis is a very common oral disease caused by periodontopathic bacteria. Antimicrobial activities and other biological\\u000a effects of LF against representative periodontopathic bacteria, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia, have been widely studied. Association of

Hiroyuki Wakabayashi; Ichiro Kondo; Tetsuo Kobayashi; Koji Yamauchi; Tomohiro Toida; Keiji Iwatsuki; Hiromasa Yoshie

2010-01-01

246

Recombinational DNA Repair in Bacteria  

E-print Network

Recombinational DNA Repair in Bacteria: Postreplication Kevin P Rice,University of Wisconsin Recombinational DNA repair represents the primary function for homologous DNA recombination in bacteria. Most of this repair occurs at replication forks that are stalled at sites of DNA damage. Introduction Deoxyribonucleic

Cox, Michael M.

247

Evolutionary relationships among photosynthetic bacteria  

Microsoft Academic Search

To understand the evolution of photosynthetic bacteria it is necessary to understand how the main groups within Bacteria have evolved from a common ancestor, a critical issue that has not been resolved in the past. Recent analysis of shared conserved inserts or deletions (indels) in protein sequences has provided a powerful means to resolve this long-standing problem in microbiology. Based

Radhey S. Gupta

2003-01-01

248

Acetic acid bacteria in oenology  

Microsoft Academic Search

Acetic acid bacteria have always been considered the bad mi- croorganisms of oenology; responsible for wine spoiling (vine- gary taint). The taxonomy and our knowledge of the metabo- lism of acetic acid bacteria are rapidly evolving, especially as new molecular biology techniques are applied to this fastidious group of microorganisms, which are still rather difficult to work with. The dramatic

A. Mas; M. J. Torija; A. González; M. Poblet; J. M. Guillamón

249

Enumeration and characterization of standard plate count bacteria in chlorinated and raw water supplies.  

PubMed Central

Nearly 700 standard plate count (SPC) bacteria were isolated from drinking water and untreated surface water and identified according to a scheme developed to permit the rapid, simple classification of microorganisms to genus, species, or group. Actinomycetes and Aeromonas species were the two most common groups of SPC bacteria in chlorinated distribution water. Aeromonas spp. and Enterobacter agglomerans were the two most common groups of SPC bacteria in raw water. Identification of bacterial populations before and after contact with chlorine (1 to 2 mg/liter) for 1 h revealed that chlorination selected for gram-positive bacteria. Water that contained high densities of bacteria known to be antagonistic to coliforms had low coliform isolation rates. The membrane filtration technique for enumerating SPC bacteria recovered significantly higher numbers (P < 0.001) than the standard pour plate technique. PMID:7447444

LeChevallier, M W; Seidler, R J; Evans, T M

1980-01-01

250

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. PMID:19239884

Waters, Lauren S.; Storz, Gisela

2011-01-01

251

Metabolic engineering of bacteria.  

PubMed

Yield and productivity are critical for the economics and viability of a bioprocess. In metabolic engineering the main objective is the increase of a target metabolite production through genetic engineering. Metabolic engineering is the practice of optimizing genetic and regulatory processes within cells to increase the production of a certain substance. In the last years, the development of recombinant DNA technology and other related technologies has provided new tools for approaching yields improvement by means of genetic manipulation of biosynthetic pathway. Industrial microorganisms like Escherichia coli, Actinomycetes, etc. have been developed as biocatalysts to provide new or to optimize existing processes for the biotechnological production of chemicals from renewable plant biomass. The factors like oxygenation, temperature and pH have been traditionally controlled and optimized in industrial fermentation in order to enhance metabolite production. Metabolic engineering of bacteria shows a great scope in industrial application as well as such technique may also have good potential to solve certain metabolic disease and environmental problems in near future. PMID:22754024

Kumar, Ravi R; Prasad, Satish

2011-07-01

252

Transformation of the gram-positive bacterium Clavibacter xyli subsp. cynodontis by electroporation with plasmids from the IncP incompatibility group.  

PubMed Central

We report the transformation of a gram-positive bacterium, Clavibacter xyli subsp. cynodontis, with several plasmids in the IncP incompatibility group from gram-negative bacteria. Our results suggest that IncP plasmids may be transferable to other gram-positive organisms. After optimizing electroporation parameters, we obtained a maximum of 2 x 10(5) transformants per microgram of DNA. The availability of a transformation system for this bacteria will facilitate its use in indirectly expressing beneficial traits in plants. PMID:1624442

Metzler, M C; Zhang, Y P; Chen, T A

1992-01-01

253

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. PMID:22837327

2012-01-01

254

Comparative Activity of Eighteen Antimicrobial Agents against Anaerobic Bacteria Isolated in South Africa  

Microsoft Academic Search

The in vitro activity of 18 antimicrobial agents was determined against 378 anaerobic bacteria isolated in Bloemfontein,\\u000a South Africa, during 1996\\/97. Against the gram-positive isolates, MICs of penicillin and cefoxitin were >0.5??g\\/ml and >16??g\\/ml,\\u000a respectively, for five and three strains of non-perfringens Clostridium spp. Seventeen Peptostreptococcus anaerobius strains were resistant to penicillin (MIC?2??g\\/ml). All gram-positive anaerobes tested except one Peptostreptococcus

M. M. Lubbe; P. L. Botha; L. J. Chalkley

1999-01-01

255

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. PMID:22933565

Amin, Shady A.; Parker, Micaela S.

2012-01-01

256

Magnetic Microstructure of Magnetotactic Bacteria by  

E-print Network

Magnetic Microstructure of Magnetotactic Bacteria by Electron Holography Rafal E. Dunin microstructure of magnetite nanocrys- tals in magnetotactic bacteria. The magnetite crystals were all single). For example, magnetotactic bacteria contain magnetosomes, which are intracellular, ferri- magnetic crystals

Dunin-Borkowski, Rafal E.

257

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

258

Bacteria can promote calcium oxalate crystal growth and aggregation.  

PubMed

Our previous report showed that uropathogenic bacteria, e.g., Escherichia coli, are commonly found inside the nidus of calcium oxalate (CaOx) kidney stones and may play pivotal roles in stone genesis. The present study aimed to prove this new hypothesis by direct examining CaOx lithogenic activities of both Gram-negative and Gram-positive bacteria. CaOx was crystallized in the absence (blank control) or presence of 10(5) CFU/ml E. coli, Klebsiella pneumoniae, Staphylococcus aureus, or Streptococcus pneumoniae. Fragmented red blood cell membranes and intact red blood cells were used as positive and negative controls, respectively. The crystal area and the number of aggregates were measured to initially screen for effects of bacteria on CaOx crystal growth and aggregation. The data revealed that all the bacteria tested dramatically increased the crystal area and number of crystal aggregates. Validation assays (spectrophotometric oxalate-depletion assay and an aggregation-sedimentation study) confirmed their promoting effects on both growth (20.17 ± 3.42, 17.55 ± 2.27, 16.37 ± 1.38, and 21.87 ± 0.85 % increase, respectively) and aggregation (57.45 ± 2.08, 51.06 ± 5.51, 55.32 ± 2.08, and 46.81 ± 3.61 % increase, respectively) of CaOx crystals. Also, these bacteria significantly enlarged CaOx aggregates, with the diameter greater than the luminal size of distal tubules, implying that tubular occlusion might occur. Moreover, these bacterial effects were dose-dependent and specific to intact viable bacteria, not intact dead or fragmented bacteria. In summary, intact viable E. coli, K. pneumoniae, S. aureus, and S. pneumoniae had significant promoting effects on CaOx crystal growth and aggregation. This functional evidence supported the hypothesis that various types of bacteria can induce or aggravate metabolic stone disease, particularly the CaOx type. PMID:23334195

Chutipongtanate, Somchai; Sutthimethakorn, Suchitra; Chiangjong, Wararat; Thongboonkerd, Visith

2013-03-01

259

Electromechanical and Elastic Probing of Bacteria in Cell Culture Medium  

PubMed Central

Rapid phenotype characterization and identification of cultured cells, which is needed for progress in tissue engineering and drug testing, requires an experimental technique that measures physical properties of cells with sub-micron resolution. Recently, band excitation piezoresponse force microscopy (BEPFM) has been proven useful for recognition and imaging of different types of bacteria in pure water. Here, the BEPFM method is performed for the first time in physiologically-relevant electrolyte media, such as Dulbecco’s phosphate-buffered saline (DPBS) and Dulbecco’s modified Eagle’s medium (DMEM). Distinct electromechanical responses for Micrococcus lysodeikticus (Gram-positive) and Pseudomonas fluorescens (Gram-negative) bacteria are demonstrated in DPBS. The results suggest that mechanical properties of the outer surface coating each bacterium, as well as the electrical double layer around them, are responsible for the BEPFM image formation mechanism in electrolyte media. PMID:22641388

Thompson, G.L.; Reukov, V.V.; Nikiforov, M.P.; Jesse, S.; Kalinin, S.V.; Vertegel, A.A.

2012-01-01

260

Diversity among Opine-Utilizing Bacteria: Identification of Coryneform Isolates  

PubMed Central

Bacteria were isolated from soil and crown gall tumors by selection in minimal medium with an opine, such as succinamopine or mannopine, as the sole carbon source. The isolates were characterized for the pattern of opine utilization and identified. They were classified as mannityl opine or imino diacid utilizers and exhibited specificity of utilization similar to that described previously for Agrobacterium species. A minority of isolates were gram negative and were identified as Agrobacterium or Pseudomonas species; most were gram positive and belonged to the coryneform group. These results indicate that any specific effect of opines on the ecology of Agrobacterium tumefaciens is modulated by activities of other types of soil- and plant-associated bacteria. PMID:16347383

Tremblay, Guy; Gagliardo, Ronald; Chilton, W. Scott; Dion, Patrice

1987-01-01

261

Geobiology of marine magnetotactic bacteria  

E-print Network

Magnetotactic bacteria (MTB) biomineralize intracellular membrane-bound crystals of magnetite (Fe3O4) or greigite (Fe3S4), and are abundant in the suboxic to anoxic zones of stratified marine environments worldwide. Their ...

Simmons, Sheri Lynn

2006-01-01

262

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

263

Where Bacteria and Languages Concur  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Genetic data from human gastric bacteria provide independent support for a linguistic analysis of Pacific population dispersals.

Colin Renfrew (University of Cambridge;McDonald Institute for Archaeological Research)

2009-01-23

264

Inclusion Proteins fromother Insecticidal Bacteria  

Microsoft Academic Search

The toxicity of Bacillus thuringiensis and B. sphaericus, insecticidal bacteria that have been used widely for insect pest and vector control, is due to insecticidal protein crystals\\u000a produced during sporulation. Whereas the insecticidal crystals of these two species have been studied extensively owing to\\u000a their practical value, there are several other lesser known entomopathogenic bacteria that also produce either crystalline

Hyun-Woo Park; Brian A. Federici; Yuko Sakano

265

Evolutionary relationships among photosynthetic bacteria  

Microsoft Academic Search

To understand the evolution of photosynthetic bacteria it is necessary to understand how the main groups within Bacteria have evolved from a common ancestor, a critical issue that has not been resolved in the past. Recent analysis of shared conserved\\u000a inserts or deletions (indels) in protein sequences has provided a powerful means to resolve this long-standing problem in\\u000a microbiology. Based

Radhey S. Gupta

2003-01-01

266

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. PMID:3426224

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

1987-01-01

267

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

268

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

269

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

270

Bioreporter bacteria for landmine detection  

SciTech Connect

Landmines (and other UXO) gradually leak explosive chemicals into the soil at significant concentrations. Bacteria, which have adapted to scavenge low concentrations of nutrients, can detect these explosive chemicals. Uptake of these chemicals results in the triggering of specific bacterial genes. The authors have created genetically recombinant bioreporter bacteria that detect small concentrations of energetic chemicals. These bacteria are genetically engineered to produce a bioluminescent signal when they contact specific explosives. A gene for a brightly fluorescent compound can be substituted for increased sensitivity. By finding the fluorescent bacteria, you find the landmine. Detection might be accomplished using stand-off illumination of the minefield and GPS technology, which would result in greatly reduced risk to the deminers. Bioreporter technology has been proven at the laboratory scale, and will be tested under field conditions in the near future. They have created a bacterial strain that detects sub-micromolar concentrations of o- and p-nitrotoluene. Related bacterial strains were produced using standard laboratory protocols, and bioreporters of dinitrotoluene and trinitrotoluene were produced, screening for activity with the explosive compounds. Response time is dependent on the growth rate of the bacteria. Although frill signal production may require several hours, the bacteria can be applied over vast areas and scanned quickly, producing an equivalent detection speed that is very fast. This technology may be applicable to other needs, such as locating buried explosives at military and ordnance/explosive manufacturing facilities.

Burlage, R.S. [Oak Ridge National Lab., TN (United States); Youngblood, T. [Frisby Technologies, Aiken, SC (United States); Lamothe, D. [American Technologies, Inc., Huntsville, AL (United States). Ordnance/Explosives Environmental Services Div.

1998-04-01

271

Correlation between structural diversity and catabolic versatility of metal-affected bacteria in soil  

NASA Astrophysics Data System (ADS)

Application of sewage sludge to an agricultural field resulted in contamination of metal. Metal affects on the the structural diversity and the catabolic versatility of bacteria capable of growing in the absence of growing factors were studied six years after sludge application. The number of strain clusters as estimated by amplified ribosomal restriction analysis (ADRDA) was reduced by 39% when comparing isolates from the control and the most contaminated soil. Concomittantly, the average number of aromatic acids utilized per isolate from among 21 substrates tested decreased from 12.28 to 5.23. This loss in catabolic versatility was greater in Gram-negative (68%) than in Gram-positive bacteria (49%). Due to bioenergetic reasons discussed, it is supposed that the catabolic versatility between Gram-negative and Gram-positive bacteria and the greater loss of this property in the former may explain why, in metal contaminated soils, Grtam-negatives are selected at the expense of Gram-positive bacteria.

Wenderoth, D. F.; Reber, H. H.; Timmis, K. N.

2003-04-01

272

Survival of gram positive anaerobic cocci on swabs and their isolation from the mouth and vagina.  

PubMed Central

The survival of Gram positive anaerobic cocci on plain cotton wool and albumin coated swabs held in various transport media was investigated. Results suggested that in most cases Amies', Stuart's and VMGII media do not offer any more protection to the bacteria than storing swabs dry in their containers. A technique was developed for the isolation and identification of Gram positive anaerobic cocci from the mouth and vagina, incorporating bicozamycin in the medium as a selective agent. Few strains were recovered from the oral cavity, but larger numbers were isolated from the vagina. Using a minimum number of antibiotic sensitivity and biochemical tests, including analysis of end products by gas-liquid chromatography, most isolates were identified to species level. PMID:3950035

Smith, G L; Cumming, C G; Ross, P W

1986-01-01

273

Platelet Activation by Streptococcus pyogenes Leads to Entrapment in Platelet Aggregates, from Which Bacteria Subsequently Escape.  

PubMed

Platelet activation and aggregation have been reported to occur in response to a number of Gram-positive pathogens. Here, we show that platelet aggregates induced by Streptococcus pyogenes were unstable and that viable bacteria escaped from the aggregates over time. This was not due to differential activation in response to the bacteria compared with physiological activators. All the bacterial isolates induced significant platelet activation, including integrin activation and alpha and dense-granule release, at levels equivalent to those induced by potent physiological platelet activators that induced stable aggregates. The ability to escape the aggregates and to resist the antibacterial effects of platelets was dependent on active protein synthesis by the bacteria within the aggregate. We conclude that S. pyogenes bacteria can temporarily cover themselves with activated platelets, and we propose that this may facilitate survival of the bacteria in the presence of platelets. PMID:25069984

Svensson, Lisbeth; Baumgarten, Maria; Mörgelin, Matthias; Shannon, Oonagh

2014-10-01

274

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

275

Isolation and phylogenetic analysis of bacteria with antimicrobial activities from the Mediterranean sponges Aplysina aerophoba and Aplysina cavernicola  

Microsoft Academic Search

The aim of this study was to isolate bacteria with antimicrobial activities from the marine sponges Aplysina aerophoba and Aplysina cavernicola. The obtained 27 isolates could be subdivided into eight phylogenetically different clusters based on comparative sequence analysis of their 16S rDNA genes. The sponge isolates were affiliated with the low (Bacillus) and high G+C Gram-positive bacteria (Arthobacter, Micrococcus), as

Ute Hentschel; Michael Schmid; Michael Wagner; Lars Fieseler; Christine Gernert

2001-01-01

276

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

277

Amphiphilic star copolymer-based bimodal fluorogenic/magnetic resonance probes for concomitant bacteria detection and inhibition.  

PubMed

Four-arm star-shaped copolymers, TPE-star-P(DMA-co-BMA-co-Gd), containing TPE cores with an aggregation-induced emission (AIE) feature, a T 1 -type magnetic resonance (MR) contrast agent, and amphiphilic cationic arms, are synthesized. By taking advantage of non-covalent interactions between star copolymers and bacteria surfaces, bimodal fluorometric/MR detection and concomitant inhibition of both Gram-positive and Gram-negative bacteria strains in aqueous media are explored. PMID:25147084

Li, Yamin; Yu, Hansen; Qian, Yinfeng; Hu, Jinming; Liu, Shiyong

2014-10-01

278

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

279

Bacteria Galore by Sunday at Four  

NSDL National Science Digital Library

This colorful picture book provides an introduction to the world of bacteria â where bacteria are found, what it is and how they spread. While the book is beautiful to look at, this childrenâs picture book is also full of accurate and interesting facts about bacteria. Author Dr. Mel Rosenberg emphasizes the colors, shapes, sizes, forms, and functions of bacteria.

Rosenberg, Mel; Niv-Dolinski, Tali

280

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

281

Induction of nitric oxide production by polyosides from the cell walls of Streptococcus mutans OMZ 175, a gram-positive bacterium, in the rat aorta.  

PubMed Central

The cardiovascular dysfunctions associated with septic shock induced by gram-negative or gram-positive bacteria (gram-positive or gram-negative septic shock) are comparable. In gram-negative septic shock, lipopolysaccharide (LPS) induces nitric oxide (NO) synthase, which contributes to the vascular hypotension and hyporeactivity to vasoconstrictors. The role of NO in gram-positive septic shock and the nature of the bacterial wall components responsible for the vascular effects of gram-positive bacteria are not well known. This study investigated the vascular effects of cell wall serotype polyosides, rhamnose glucose polymers (RGPs), from Streptococcus mutans, in comparison with lipoteichoic acid (LTA) from Staphylococcus aureus, on the induction of NO synthase activity in the rat aorta. We show that 10 microg of both RGPs and LTA per ml induced hyporeactivity to noradrenaline, L-arginine-induced relaxation, increases of 2.2- and 7.8-fold, respectively, of cyclic GMP production, and increases of 7- and 12-fold in nitrite release. All of these effects appeared after several hours of incubation and were inhibited by N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase. Electron paramagnetic resonance spin trapping experiments demonstrated directly that RGPs and LTA induced NO overproduction (four- to eightfold, respectively) in rat aortic rings; this production was inhibited by L-NAME and prevented by dexamethasone. These results demonstrate directly the induction of NO production in vascular tissue by LTA and show that another, chemically different component of gram-positive bacteria can also have these properties. This result suggests that different components of the gram-positive bacterial wall could be implicated in the genesis of cardiovascular dysfunctions observed in gram-positive septic shock. PMID:9169734

Martin, V; Kleschyov, A L; Klein, J P; Beretz, A

1997-01-01

282

In Vitro Activity of TD-1792, a Multivalent Glycopeptide-Cephalosporin Antibiotic, against 377 Strains of Anaerobic Bacteria and 34 Strains of Corynebacterium Species  

PubMed Central

TD-1792 is a multivalent glycopeptide-cephalosporin heterodimer antibiotic with potent activity against Gram-positive bacteria. We tested TD-1792 against 377 anaerobes and 34 strains of Corynebacterium species. Against nearly all Gram-positive strains, TD-1792 had an MIC90 of 0.25 ?g/ml and was typically 3 to 7 dilutions more active than vancomycin and daptomycin. PMID:22290981

Citron, Diane M.; Warren, Yumi A.; Goldstein, Ellie J. C.

2012-01-01

283

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 PMID:1785935

Nierzwicki-Bauer, S A; Aulfinger, H

1991-01-01

284

Characterization of predominant bacteria isolates from clean rooms in a pharmaceutical production unit*  

PubMed Central

Aims: To screen for the predominant bacteria strains distributed in clean rooms and to analyze their phylogenetic relationships. Methods and Results: The bacteria distributed in air, surfaces and personnel in clean rooms were routinely monitored using agar plates. Five isolates frequently isolated from the clean rooms of an aseptic pharmaceutical production workshop were selected based on their colony and cell morphology characteristics. Their physiological and biochemical properties, as well as partial 16S rDNA sequences, were analyzed. Results showed that all the five isolates belong to Gram positive bacteria, of which three were Staphylococcus, one Microbacterium and one Bacillus species. Sensitivity tests for these bacteria isolates to 3 disinfectants showed that isolate F03 was obtuse, and had low susceptivity to UV irradiation, while isolates F02, F01 and F04 were not sensitive to phenol treatment. Isolates F04, F01 and F05 were resistant to chlorhexidine gluconate. Conclusion: Bacteria widely distributed in clean rooms are mainly a group of Gram positive strains, showing high resistance to selected disinfectants. Significance and impact of the study: Clean rooms are essential in aseptic pharmaceutical and food production. Screening bacteria isolates and identifying them is part of good manufacturing practices, and will aid in finding a more effective disinfection method. PMID:17726748

Wu, Gen-fu; Liu, Xiao-hua

2007-01-01

285

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

286

A Green Nonsulfur Bacterium, Dehalococcoides ethenogenes, with the LexA-binding sequence found in Gram-positive organisms  

SciTech Connect

Dehalococcoides ethenogenes is a member of the physiologically diverse division of green nonsulfur bacteria. Using a TBLASTN search, the D. ethenogenes lexA gene has been identified, cloned, and expressed and its protein has been purified. Mobility shift assays revealed that the D. ethenogenes LexA protein specifically binds to both its own promoter and that of the uvrA gene, but not to the recA promoter. Our results demonstrate that the D. ethenogenes LexA binding site is GAACNNNNGTTC, which is identical to that found in gram-positive bacteria. In agreement with this fact, the Bacillus subtilis DinR protein binds specifically to the D. ethenogenes LexA operator. This constitutes the first non-gram-positive bacterium exhibiting a LexA binding site identical to that of B. subtilis.

de Henestrosa, Antonio R. (Barcelona, University of); Cune, Jordi (Barcelona, University of); Erill, Ivan (Barcelona, University of); Magnuson, Jon K. (BATTELLE (PACIFIC NW LAB)); Barbe, Jordi (Barcelona, University of)

2002-12-01

287

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

288

Mechanical resonances of bacteria cells.  

PubMed

The quality of the natural vibrations of specific bacteria is investigated using a shell model which accounts for the elastic properties of the membrane and the associated viscosities of the cytoplasma and the surrounding fluid. The motion of the membrane is approximated in terms of the distribution of internal forces over the shell thickness, which is assumed to be much less than the size of the cell. Flexural moments and intersecting stresses are neglected. Using experimentally obtained values for the membrane properties, high-quality resonances are predicted for several types of bacteria which have radii greater than 5 microm. Viscous shear waves are the main source of energy dissipation as has been previously reported in other studies on the natural oscillations of red blood cells, drops, and bubbles. Implications for the acoustic mediated destruction of bacteria are discussed. PMID:16485974

Zinin, P V; Allen, J S; Levin, V M

2005-12-01

289

Mechanical consequences of cell-wall turnover in the elongation of a Gram-positive bacterium.  

PubMed

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. PMID:23746506

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

2013-06-01

290

[Electron microscope investigation of bacteria associated with the tegument of the tapeworm species Eubothrium rugosum, a parasite of the intestine of burbot].  

PubMed

Bacteria associated with the tegument of the tapeworm species Eubothrium rugosum (Cestoda, Pseudophyllidea) parasitizing the intestine of burbot (Lota lota) were studied using transmission and scanning electron microscopy. Three morphological types of the bacteria were revealed. Bacteria of the first type are localized between microtrichia and fit to them closely. Bacteria of the second (gram-positive) and third (gram-negative) types are localized over microtrichia of the tegument and do not attach to the surface. Physiological functions of the bacteria are discussed. PMID:16134784

Poddubnaia, L G

2005-01-01

291

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

292

pH Dependent Charging Behavior of Isolated Cell Walls of a Gram-Positive Soil Bacterium  

Microsoft Academic Search

The cell walls of Gram-positive bacteria are highly porous structures. Peptidoglycan, the main component of these cell walls, contains many acidic groups, leading to a pH- and salt-dependent charge. This charge is involved in many processes, such as the attachment to surfaces and the binding of metal ions. Acid-base titrations are performed on cell wall material from Rhodococcus erythropolis AI77,

Alexandra C. C. Plette; Willem H. van Riemsdijk; Marc F. Benedetti; Albert van der Wal

1995-01-01

293

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. PMID:23616932

Abedon, Stephen T.

2011-01-01

294

Poles apart: biodiversity and biogeography of sea ice bacteria.  

PubMed

This review introduces the subjects of bacterial biodiversity and biogeography. Studies of biogeography are important for understanding biodiversity, the occurrence of threatened species, and the ecological role of free-living and symbiotic prokaryotes. A set of postulates is proposed for biogeography as a guide to determining whether prokaryotes are "cosmopolitan" (found in more than one geographic location on Earth) or candidate endemic species. The term "geovar" is coined to define a geographical variety of prokaryote that is restricted to one area on Earth or one host species. This review discusses sea ice bacteriology as a test case for examining bacterial diversity and biogeography. Approximately 7% of Earth's surface is covered by sea ice, which is colonized principally by psychrophilic microorganisms. This extensive community of microorganisms, referred to as the sea ice microbial community (SIMCO), contains algae (mostly diatoms), protozoa, and bacteria. Recent investigations indicate that the sea ice bacteria fall into four major phylogenetic groups: the proteobacteria, the Cytophaga-Flavobacterium-Bacteroides (CFB) group, and the high and low mol percent gram-positive bacteria. Archaea associated with sea ice communities have also been reported. Several novel bacterial genera and species have been discovered, including Polaromonas, Polaribacter, Psychroflexus, Gelidibacter, and Octadecabacter; many others await study. Some of the gram-negative sea ice bacteria have among the lowest maximum temperatures for growth known, < 10 degrees C for some strains. The polar sea ice environment is an ideal habitat for studying microbial biogeography because of the dispersal issues involved. Dispersal between poles is problematic because of the long distances and the difficulty of transporting psychrophilic bacteria across the equator. Studies to date indicate that members of some genera occur at both poles; however, cosmopolitan species have not yet been discovered. Additional research on polar sea ice bacteria is needed to resolve this issue and extend our understanding of its microbial diversity. PMID:10547690

Staley, J T; Gosink, J J

1999-01-01

295

Antimicrobial Photodynamic Therapy to Kill Gram-negative Bacteria  

PubMed Central

Antimicrobial photodynamic therapy (PDT) or photodynamic inactivation (PDI) is a new promising strategy to eradicate pathogenic microorganisms such as Gram-positive and Gram-negative bacteria, yeasts and fungi. The search for new approaches that can kill bacteria but do not induce the appearance of undesired drug-resistant strains suggests that PDT may have advantages over traditional antibiotic therapy. PDT is a non-thermal photochemical reaction that involves the simultaneous presence of visible light, oxygen and a dye or photosensitizer (PS). Several PS have been studied for their ability to bind to bacteria and efficiently generate reactive oxygen species (ROS) upon photostimulation. ROS are formed through type I or II mechanisms and may inactivate several classes of microbial cells including Gram-negative bacteria such as Pseudomonas aeruginosa, which are typically characterized by an impermeable outer cell membrane that contains endotoxins and blocks antibiotics, dyes, and detergents, protecting the sensitive inner membrane and cell wall. This review covers significant peer-reviewed articles together with US and World patents that were filed within the past few years and that relate to the eradication of Gram-negative bacteria via PDI or PDT. It is organized mainly according to the nature of the PS involved and includes natural or synthetic food dyes; cationic dyes such as methylene blue and toluidine blue; tetrapyrrole derivatives such as phthalocyanines, chlorins, porphyrins, chlorophyll and bacteriochlorophyll derivatives; functionalized fullerenes; nanoparticles combined with different PS; other formulations designed to target PS to bacteria; photoactive materials and surfaces; conjugates between PS and polycationic polymers or antibodies; and permeabilizing agents such as EDTA, PMNP and CaCl2. The present review also covers the different laboratory animal models normally used to treat Gram-negative bacterial infections with antimicrobial PDT. PMID:23550545

Sperandio, Felipe F; Huang, Ying-Ying; Hamblin, Michael R

2013-01-01

296

Antibacterial activity of the essential oil of Picea excelsa on Listeria, Staphylococcus aureus and coliform bacteria  

Microsoft Academic Search

Antibacterial activity of essential oil of Picea excelsa was tested with the dilution method against one strain of Listeria ivanovii, six of L. monocytogenes, three of Staphylococcus aureus, three of Escherichia coli, one of Klebsiella oxytoca, one of K. pneumoniae subsp. pneumoniae and one of Enterobacter cloacae. For Gram-positive bacteria in stationary phase, 0·07% of essential oil inhibited about 105colony

N. Canillac; A. Mourey

2001-01-01

297

Antibacterial potentiality of Argemone mexicana solvent extracts against some pathogenic bacteria.  

PubMed

The sensitivity of two Gram positive (Staphylococcus aureus and Bacillus subtilis) and two Gram negative (Escherichia coli and Pseudomonas aeruginosa) pathogenic multi-drug resistant bacteria was tested against the crude extracts (cold aqueous, hot aqueous, and methanol extracts) of leaves and seeds of Argemone mexicana L. (Papaveraceae) by agar well diffusion method. Though all the extracts were found effective, yet the methanol extract showed maximum inhibition against the test microorganisms followed by hot aqueous extract and cold aqueous extract. PMID:17072477

Bhattacharjee, Indranil; Chatterjee, Soroj Kumar; Chatterjee, Soumendranath; Chandra, Goutam

2006-09-01

298

In vitro Activity of Augmentin against Pathogenic Bacteria and Its Comparison with Other Antibiotics  

Microsoft Academic Search

190 isolates from clinical specimens were tested in vitro to determine their susceptibility pattern against augmentin. Of the 132 strains of Enterobacteriaceae tested, 109 (82.6%) were susceptible. 41 (93.2%) of the 44 gram-positive bacteria tested were also susceptible to augmentin. Strains of Pseudomonas aeruginosa and Serratia marcescens were resistant to augmentin. However, augmentin showed increased activity against Escherichia coli, and

Fred Perryman; Steve Johnson; Hussain Qadri

1983-01-01

299

Interaction of a free-living soil nematode, Caenorhabditis elegans, with surrogates of foodborne pathogenic bacteria.  

PubMed

Free-living nematodes may harbor, protect, and disperse bacteria, including those ingested and passed in viable form in feces. These nematodes are potential vectors for human pathogens and may play a role in foodborne diseases associated with fruits and vegetables eaten raw. In this study, we evaluated the associations between a free-living soil nematode, Caenorhabditis elegans, and Escherichia coli, an avirulent strain of Salmonella Typhimurium, Listeria welshimeri, and Bacillus cereus. On an agar medium, young adult worms quickly moved toward colonies of all four bacteria; over 90% of 3-day-old adult worms entered colonies within 16 min after inoculation. After 48 h, worms moved in and out of colonies of L. welshimeri and B. cereus but remained associated with E. coli and Salmonella Typhimurium colonies for at least 96 h. Young adult worms fed on cells of the four bacteria suspended in K medium. Worms survived and reproduced with the use of nutrients derived from all test bacteria, as determined for eggs laid by second-generation worms after culturing for 96 h. Development was slightly slower for worms fed gram-positive bacteria than for worms fed gram-negative bacteria. Worms that fed for 24 h on bacterial lawns formed on tryptic soy agar dispersed bacteria over a 3-h period when they were transferred to a bacteria-free agar surface. The results of this study suggest that C. elegans and perhaps other free-living nematodes are potential vectors for both gram-positive and gram-negative bacteria, including foodborne pathogens in soil. PMID:14503703

Anderson, Gary L; Caldwell, Krishaun N; Beuchat, Larry R; Williams, Phillip L

2003-09-01

300

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. PMID:18712518

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

2009-01-01

301

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

302

Immune responses to intracellular bacteria.  

PubMed

The multifaceted dialogue between intracellular bacteria and the mammalian host continues to be an exciting issue from both the scientific and public-health viewpoint. The recent year has witnessed some particularly impressive progress in knowledge about the two major culprits affecting the health of mankind, Mycobacterium tuberculosis and Salmonella typhi - the causative agents of tuberculosis and typhoid fever. PMID:11498297

Raupach, B; Kaufmann, S H

2001-08-01

303

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. PMID:20930075

Chang, Alicia H.; Parsonnet, Julie

2010-01-01

304

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

305

News and Research Good Bacteria  

E-print Network

Is A No-brainer For Symbiotic Bacteria 9-4-2003 Humans may learn cooperation in kindergarten, but what penalizing rhizobial species that "cheat" on the symbiotic relationship by fixing little or no nitrogen cooperation by exacting a toll on those bacterial strains that don't hold up their end of the symbiotic

West, Stuart

306

Biopreservation by lactic acid bacteria  

Microsoft Academic Search

Biopreservation refers to extended storage life and enhanced safety of foods using the natural microflora and (or) their antibacterial products. Lactic acid bacteria have a major potential for use in biopreservation because they are safe to consume and during storage they naturally dominate the microflora of many foods. In milk, brined vegetables, many cereal products and meats with added carbohydrate,

Michael E. Stiles

1996-01-01

307

Glycopeptide Resistance in Gram-Positive Cocci: A Review  

PubMed Central

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

308

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. PMID:23393147

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

2013-01-01

309

Streptococcus mutans: a new Gram-positive paradigm?  

PubMed

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. PMID:23393147

Lemos, José A; Quivey, Robert G; Koo, Hyun; Abranches, Jacqueline

2013-03-01

310

In vitro growth inhibition of mastitis causing bacteria by phenolics and metal chelators  

SciTech Connect

Antimicrobial activities of three phenolic compounds and four metal chelators were tested at 0, 250, 500, and 1000 ppm in vitro against four major mastitis-causing bacteria, Streptococcus agalactiae, Staphylococcus aureus, Klebsiella pnuemoniae, and Escherichia coli. Overall, butylated hydroxyanisole and tert-butylhydroquinone showed the greatest antimicrobial activity. These phenolics were bactericidal at 250 to 500 ppm against all four bacteria tested. The butylated hydroxytoluene was bactericidal against the gram-positive bacteria but was ineffective against the coliforms. At 250 ppm, disodium ethylenediaminetetraacetic acid was bactericidal against the gram-positive bacteria but much less effective against the gram-negatives. However, diethylene-triaminepentaacetic acid was more growth inhibitory than ethylenediaminetetraacetic acid against the gram-negative bacteria and especially against Escherichia coli. All other compounds were generally much less effective or ineffective against all four microorganisms. Therefore, butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid may have practical implications in the prevention or treatment of bovine mastitis.

Chew, B.P.; Tjoelker, L.W.; Tanaka, T.S.

1985-11-01

311

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. PMID:24893651

2014-01-01

312

New and Rare Carotenoids Isolated from Marine Bacteria and Their Antioxidant Activities  

PubMed Central

Marine bacteria have not been examined as extensively as land bacteria. We screened carotenoids from orange or red pigments-producing marine bacteria belonging to rare or novel species. The new acyclic carotenoids with a C30 aglycone, diapolycopenedioc acid xylosylesters A–C and methyl 5-glucosyl-5,6-dihydro-apo-4,4?-lycopenoate, were isolated from the novel Gram-negative bacterium Rubritalea squalenifaciens, which belongs to phylum Verrucomicrobia, as well as the low-GC Gram-positive bacterium Planococcus maritimus strain iso-3 belonging to the class Bacilli, phylum Firmicutes, respectively. The rare monocyclic C40 carotenoids, (3R)-saproxanthin and (3R,2?S)-myxol, were isolated from novel species of Gram-negative bacteria belonging to the family Flavobacteriaceae, phylum Bacteroidetes. In this review, we report the structures and antioxidant activities of these carotenoids, and consider relationships between bacterial phyla and carotenoid structures. PMID:24663119

Shindo, Kazutoshi; Misawa, Norihiko

2014-01-01

313

Non-classical protein secretion in bacteria  

PubMed Central

Background We present an overview of bacterial non-classical secretion and a prediction method for identification of proteins following signal peptide independent secretion pathways. We have compiled a list of proteins found extracellularly despite the absence of a signal peptide. Some of these proteins also have known roles in the cytoplasm, which means they could be so-called "moon-lightning" proteins having more than one function. Results A thorough literature search was conducted to compile a list of currently known bacterial non-classically secreted proteins. Pattern finding methods were applied to the sequences in order to identify putative signal sequences or motifs responsible for their secretion. We have found no signal or motif characteristic to any majority of the proteins in the compiled list of non-classically secreted proteins, and conclude that these proteins, indeed, seem to be secreted in a novel fashion. However, we also show that the apparently non-classically secreted proteins are still distinguished from cellular proteins by properties such as amino acid composition, secondary structure and disordered regions. Specifically, prediction of disorder reveals that bacterial secretory proteins are more structurally disordered than their cytoplasmic counterparts. Finally, artificial neural networks were used to construct protein feature based methods for identification of non-classically secreted proteins in both Gram-positive and Gram-negative bacteria. Conclusion We present a publicly available prediction method capable of discriminating between this group of proteins and other proteins, thus allowing for the identification of novel non-classically secreted proteins. We suggest candidates for non-classically secreted proteins in Escherichia coli and Bacillus subtilis. The prediction method is available online. PMID:16212653

Bendtsen, Jannick D; Kiemer, Lars; Fausb?ll, Anders; Brunak, S?ren

2005-01-01

314

Antagonism of Lactic Acid Bacteria against Phytopathogenic Bacteria  

PubMed Central

A variety of lactic acid bacteria, isolated from plant surfaces and plant-associated products, were found to be antagonistic to test strains of the phytopathogens Xanthomonas campestris, Erwinia carotovora, and Pseudomonas syringae. Effective “in vitro” inhibition was found both on agar plates and in broth cultures. In pot trials, treatment of bean plants with a Lactobacillus plantarum strain before inoculation with P. syringae caused a significant reduction of the disease incidence. Images PMID:16347150

Visser, Ronel; Holzapfel, Wilhelm H.; Bezuidenhout, Johannes J.; Kotze, Johannes M.

1986-01-01

315

Gram-positive and gram-negative bacterial toxins in sepsis: a brief review.  

PubMed

Bacterial sepsis is a major cause of fatality worldwide. Sepsis is a multi-step process that involves an uncontrolled inflammatory response by the host cells that may result in multi organ failure and death. Both gram-negative and gram-positive bacteria play a major role in causing sepsis. These bacteria produce a range of virulence factors that enable them to escape the immune defenses and disseminate to remote organs, and toxins that interact with host cells via specific receptors on the cell surface and trigger a dysregulated immune response. Over the past decade, our understanding of toxins has markedly improved, allowing for new therapeutic strategies to be developed. This review summarizes some of these toxins and their role in sepsis. PMID:24193365

Ramachandran, Girish

2014-01-01

316

Monensin-based medium for determination of total gram-negative bacteria and Escherichia coli.  

PubMed Central

Plate count-monensin-KCl (PMK) agar, for enumeration of both gram-negative bacteria and Escherichia coli, is composed of (per liter) 23.5 g of plate count agar, 35 mg of monensin, 7.5 g of KCl, and 75 mg of 4-methylumbelliferyl-beta-D-glucuronide (MUG). Monensin was added after the medium was sterilized. The diluent of choice for use with PMK agar was 0.1% peptone (pH 6.8); other diluents were unsatisfactory. Gram-negative bacteria (selected for by the ionophore monensin) can be used to judge the general quality or sanitary history of a commodity. E. coli (differentiated by its ability to hydrolyze the fluorogenic compound MUG) can be used to assess the safety of a commodity in regard to the possible presence of enteric pathogens. Pure-culture studies demonstrated that monensin completely inhibited gram-positive bacteria and had little or no effect on gram-negative bacteria. When gram-negative bacteria were injured by one of several methods, a few species (including E. coli) became sensitive to monensin; this sensitivity was completely reversed in most instances by the inclusion of KCl in the medium. When PMK agar was tested with food and environmental samples, 96% of 535 isolates were gram negative; approximately 68% of colonies from nonselective medium were gram negative. PMK agar was more selective than two other media against gram-positive bacteria and was less inhibitory for gram-negative bacteria. However, with water samples, KCl had an inhibitory effect on gram-negative bacteria, and it should therefore be deleted from monensin-containing medium for water analysis.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3890742

Petzel, J P; Hartman, P A

1985-01-01

317

Monensin-based medium for determination of total gram-negative bacteria and Escherichia coli.  

PubMed

Plate count-monensin-KCl (PMK) agar, for enumeration of both gram-negative bacteria and Escherichia coli, is composed of (per liter) 23.5 g of plate count agar, 35 mg of monensin, 7.5 g of KCl, and 75 mg of 4-methylumbelliferyl-beta-D-glucuronide (MUG). Monensin was added after the medium was sterilized. The diluent of choice for use with PMK agar was 0.1% peptone (pH 6.8); other diluents were unsatisfactory. Gram-negative bacteria (selected for by the ionophore monensin) can be used to judge the general quality or sanitary history of a commodity. E. coli (differentiated by its ability to hydrolyze the fluorogenic compound MUG) can be used to assess the safety of a commodity in regard to the possible presence of enteric pathogens. Pure-culture studies demonstrated that monensin completely inhibited gram-positive bacteria and had little or no effect on gram-negative bacteria. When gram-negative bacteria were injured by one of several methods, a few species (including E. coli) became sensitive to monensin; this sensitivity was completely reversed in most instances by the inclusion of KCl in the medium. When PMK agar was tested with food and environmental samples, 96% of 535 isolates were gram negative; approximately 68% of colonies from nonselective medium were gram negative. PMK agar was more selective than two other media against gram-positive bacteria and was less inhibitory for gram-negative bacteria. However, with water samples, KCl had an inhibitory effect on gram-negative bacteria, and it should therefore be deleted from monensin-containing medium for water analysis.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3890742

Petzel, J P; Hartman, P A

1985-04-01

318

Zinc isotope fractionation during surface adsorption by bacteria  

NASA Astrophysics Data System (ADS)

The cycling and transport of zinc (Zn) in natural waters is partly controlled by its adsorption and uptake by bacterial communities. These reactions are reflected in changes in the ratios of stable Zn isotopes; however, the magnitudes and directions of these changes are largely unconstrained. In the current work, we attempt to define Zn isotope fractionation factors for bacteria-Zn interactions by performing adsorption experiments with representative Gram-positive (Bacillus subtilis) and Gram-negative (Pseudomonas mendocina) bacteria. Experiments included, (1) pH-dependent adsorption using differing bacteria:Zn ratios, (2) Zn loading at constant pH, and (3) kinetics and reversibility experiments. Results indicate that Zn adsorption is fully reversible for both bacterial species. Moreover, under the same experimental conditions both bacterial species adsorbed Zn to similar extents. Initial isotopic analysis (using a Nu Instruments MC-ICP-MS) demonstrates that, as the extent of adsorption increases, the heavier Zn isotopes are preferentially incorporated as bacterial-surface complexes. Under conditions of low bacteria:Zn ratio, the ?66Znbacteria-solution was about 0.3% for both bacterial species. This separation factor is similar to that found in other studies involving the complexation of Zn with biologic or organic components. For example, the complexation of Zn with Purified Humic Acid (PHA) resulted in a ?66ZnPHA-solution of +0.24% [1], and sorption of Zn onto two separate diatom species resulted in ?66Znsolid-solution of +0.43% and +0.27%, respectively [2]. These results suggest that Zn complexation with functional groups common to bacteria and natural organic matter may be a process that universally incorporates the heavier Zn isotopes. Our current work is focused on quantifying Zn isotope fractionation during metabolic incorporation by separating this effect from surface adsorption reactions. [1] Jouvin et al., (2009) Environ. Sci. Technol., 43(15) 5747-5754. [2] Gélabert et al., (2006) Geochim. Cosmochim. Acta 70(4) 839-857.

Kafantaris, F. A.; Borrok, D. M.

2011-12-01

319

Sand Beach Bacteria: Enumeration and Characterization  

PubMed Central

Bacteria in the water-saturated sand of a relatively unpolluted sand beach were enumerated by direct microscope and viable counting. The number of interstitial bacteria was estimated to be a significant fraction of the total number of bacteria present. Three hundred sixty-two strains were isolated and submitted to cultural and biochemical tests. Fermentational abilities and the production of indole suggested that a significant number of these bacteria were symbiotically associated with resident metazoans. PMID:4356458

Khiyama, H. M.; Makemson, J. C.

1973-01-01

320

Simple chamber facilitates chemiluminescent detection of bacteria  

NASA Technical Reports Server (NTRS)

Test chamber enables rapid estimation of bacteria in a test sample through the reaction of luminol and an oxidant with the cytochrome C portion of certain species of bacteria. Intensity of the light emitted in the reaction is a function of the specific bacteria in the test sample.

Marts, E. C.; Wilkins, J. R.

1970-01-01

321

Mobile DNA in obligate intracellular bacteria  

Microsoft Academic Search

The small genomes of obligate intracellular bacteria are often presumed to be impervious to mobile DNA and the fluid genetic processes that drive diversification in free-living bacteria. Categorized by reductive evolution and streamlining, the genomes of some obligate intracellular bacteria manifest striking degrees of stability and gene synteny. However, recent findings from complete genome sequences of obligate intracellular species and

William S. Reznikoff; Seth R. Bordenstein

2005-01-01

322

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

323

Diversity of endophytic bacteria in Brazilian sugarcane  

Microsoft Academic Search

Endophytic bacteria live inside plant tissues without caus- ing disease. Studies of endophytes in sugarcane have focused on the iso- lation of diazotrophic bacteria. We examined the diversity of endophytic bacteria in the internal tissues of sugarcane stems and leaves, using mo- lecular and biochemical methods. Potato-agar medium was used to cul- tivate the endophytes; 32 isolates were selected for

G. S. Magnani; C. M. Didonet; L. M. Cruz; C. F. Picheth; F. O. Pedrosa; E. M. Souza

2010-01-01

324

Drosophila lifespan enhancement by exogenous bacteria  

E-print Network

Drosophila lifespan enhancement by exogenous bacteria Ted Brummel*, Alisa Ching*, Laurent Seroude with customary procedure. The experiments revealed that the presence of bacteria during the first week of adult life can enhance lifespan, despite unchanged food intake. Later in life, the presence of bacteria can

Seroude, Laurent

325

Bacteria Fate and Movement Dr. Claire Baffaut  

E-print Network

Bacteria Fate and Movement Dr. Claire Baffaut Dr. Jeff Arnold And John Schumacher #12;Foliar Application Die-off/Re-growth Washoff Infiltration Leaching Runoff Surface Application Bacteria Fate Die-off/Re-growth Die-off/Re-growth #12;Movement in runoff and leaching On plants Bact_Plt = GC*Bact_App Bacteria

326

3, 765778, 2006 Culturable bacteria in  

E-print Network

BGD 3, 765­778, 2006 Culturable bacteria in Himalayan ice S. Zhang et al. Title Page Abstract Biogeosciences Discussions is the access reviewed discussion forum of Biogeosciences Culturable bacteria Correspondence to: S. Hou (shugui@lzb.ac.cn) 765 #12;BGD 3, 765­778, 2006 Culturable bacteria in Himalayan ice S

Boyer, Edmond

327

Acidophilic, heterotrophic bacteria of acidic mine waters  

Microsoft Academic Search

Obligately acidophilic, heterotrophic bacteria were isolated both from enrichment cultures developed with acidic mine water and from natural mine drainage. The bacteria were grouped by the ability to utilize a number of organic acids as sole carbon sources. None of the strains were capable of chemolithotrophic growth on inorganic reduced iron and sulfur compounds. All bacteria were rod shaped, gram

P. L. Wichlacz; R. F. Unz

1981-01-01

328

Characterization of psychrotolerant heterotrophic bacteria from Finnish Lapland.  

PubMed

A total of 331 aerobic heterotrophic bacterial strains were isolated from various ecosystems of Finnish Lapland (68-69 degrees N) including forest soil, arctic alpine-tundra soil, stream water, lake and mire sediments, lichen and snow algae. Whole cell fatty acid and 16S rRNA gene sequence analysis and microscopy indicated that the isolates were dominated by Gram-negative bacteria, while only 20 Gram-positive strains were isolated. Based on 16S rRNA gene sequences the isolates were members of alpha-, beta-, gamma-Proteobacteria, Gram-positives with low G+C content, Actinobacteria and the Cytophaga/Flexibacter/Bacteroides group. More than one-third of the isolates could be tentatively identified as Pseudomonas spp. which were particularly abundant in the alpine-tundra soils where they represented 60% of all isolates. Other frequently isolated Gram-negative taxa were Burkholderia sp., Collimonas sp., Pedobacter sp., Janthinobacter sp., Duganella sp., Dyella sp. and Sphingomonas sp. Growth temperature ranges and hydrolytic enzyme activities of selected ca.100 strains were screened. The strains were psychrotolerant growing generally at temperatures ranging from 0 to 30 degrees C, as 82% of the isolates grew at 0 degrees C while only 7% grew at 35 degrees C. Protease and lipase activities at 5 degrees C were detected in more than half of the strains while approximately 20% of the strains possessed amylase and/or cellulase activities. PMID:16564959

Männistö, Minna K; Häggblom, Max M

2006-04-01

329

Swimming bacteria power microscopic gears  

SciTech Connect

Whereas the laws of thermodynamics prohibit extraction of useful work from the Brownian motion of particles in equilibrium, these motions can be “rectified” under nonequilibrium conditions, for example, in the presence of asymmetric geometrical obstacles. Here, we describe a class of systems in which aerobic bacteria Bacillus subtilis moving randomly in a fluid film power submillimeter gears and primitive systems of gears decorated with asymmetric teeth. The directional rotation is observed only in the regime of collective bacterial swimming and the gears’ angular velocities depend on and can be controlled by the amount of oxygen available to the bacteria. The ability to harness and control the power of collective motions appears an important requirement for further development of mechanical systems driven by microorganisms.

Sokolov, Andrey; Apodaca, Mario M.; Grzybowski, Bartosz A.; Aranson, Igor S.

2010-01-01

330

Dissipative Shocks behind Bacteria Gliding  

E-print Network

Gliding is a means of locomotion on rigid substrates utilized by a number of bacteria includingmyxobacteria and cyanobacteria. One of the hypotheses advanced to explain this motility mechanism hinges on the role played by the slime filaments continuously extruded from gliding bacteria. This paper solves in full a non-linear mechanical theory that treats as dissipative shocks both the point where the extruded slime filament comes in contact with the substrate, called the filament's foot, and the pore on the bacterium outer surface from where the filament is ejected. We prove that kinematic compatibility for shock propagation requires that the bacterium uniform gliding velocity (relative to the substrate) and the slime ejecting velocity (relative to the bacterium) must be equal, a coincidence that seems to have already been observed.

Virga, Epifanio G

2014-01-01

331

Swimming bacteria power microscopic gears.  

SciTech Connect

Whereas the laws of thermodynamics prohibit extraction of useful work from the Brownian motion of particles in equilibrium, these motions can be 'rectified' under nonequilibrium conditions, for example, in the presence of asymmetric geometrical obstacles. Here, we describe a class of systems in which aerobic bacteria Bacillus subtilis moving randomly in a fluid film power submillimeter gears and primitive systems of gears decorated with asymmetric teeth. The directional rotation is observed only in the regime of collective bacterial swimming and the gears angular velocities depend on and can be controlled by the amount of oxygen available to the bacteria. The ability to harness and control the power of collective motions appears an important requirement for further development of mechanical systems driven by microorganisms.

Sokolov, A.; Apodaca, M. M.; Grzybowski, B. A.; Aranson, I. S.; Materials Science Division; Princeton Univ.; Northwestern Univ.

2010-01-19

332

Swimming bacteria power microscopic gears  

PubMed Central

Whereas the laws of thermodynamics prohibit extraction of useful work from the Brownian motion of particles in equilibrium, these motions can be “rectified” under nonequilibrium conditions, for example, in the presence of asymmetric geometrical obstacles. Here, we describe a class of systems in which aerobic bacteria Bacillus subtilis moving randomly in a fluid film power submillimeter gears and primitive systems of gears decorated with asymmetric teeth. The directional rotation is observed only in the regime of collective bacterial swimming and the gears’ angular velocities depend on and can be controlled by the amount of oxygen available to the bacteria. The ability to harness and control the power of collective motions appears an important requirement for further development of mechanical systems driven by microorganisms. PMID:20080560

Sokolov, Andrey; Apodaca, Mario M.; Grzybowski, Bartosz A.; Aranson, Igor S.

2010-01-01

333

Dissipative shocks behind bacteria gliding.  

PubMed

Gliding is a means of locomotion on rigid substrates used by a number of bacteria, including myxobacteria and cyanobacteria. One of the hypotheses advanced to explain this motility mechanism hinges on the role played by the slime filaments continuously extruded from gliding bacteria. This paper solves, in full, a non-linear mechanical theory that treats as dissipative shocks both the point where the extruded slime filament comes into contact with the substrate, called the filament's foot, and the pore on the bacterium outer surface from where the filament is ejected. I prove that kinematic compatibility for shock propagation requires that the bacterium uniform gliding velocity (relative to the substrate) and the slime ejecting velocity (relative to the bacterium) must be equal, a coincidence that seems to have already been observed. PMID:25332385

Virga, Epifanio G

2014-11-28

334

Compartmentalization of bacteria in microcapsules.  

PubMed

Lactobacillus plantarum strain 423 was encapsulated in hollow poly(organosiloxane) microcapsules by templating water-in-oil Pickering emulsion droplets via the interfacial reaction of alkylchlorosilanes. The bacteria were suspended in growth medium or buffer to protect the cells against pH changes during the interfacial reactions with alkylchlorosilanes. The results of this work open up novel avenues for the encapsulation of microbial cells. PMID:25351443

van Wijk, Judith; Heunis, Tiaan; Harmzen, Elrika; Dicks, Leon M T; Meuldijk, Jan; Klumperman, Bert

2014-12-18

335

Dispersal dynamics of groundwater bacteria  

Microsoft Academic Search

Dispersal of bacteria in saturated, porous soils can be characterized by the partitioning of cells between the aqueous and\\u000a solid phases, as a result of the physical and chemical nature of the soil and water and cell surface modifications. The purpose\\u000a of this work is to understand variations in partitioning as a consequence of the nutrient conditions and to use

Roland Lindqvist; Göran Bengtsson

1991-01-01

336

Bacteria Allocation Using Monte Carlo  

NSDL National Science Digital Library

This applet, created by David Hill and Lila Roberts, uses the Monte Carlo technique to simulate a count of bacteria that are present as a result of a certain sampling process. This simulation could be modified to perform other experiments. This experiment is geared towards high school calculus students or probability courses for mathematics majors in college. Students must possess a basic understanding of probability concepts before performing this experiment. Overall, it is a nice activity for a mathematics classroom.

Hill, David R.; Roberts, Lila F.

2009-11-24

337

Anaerobic bacteria from hypersaline environments.  

PubMed Central

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

1994-01-01

338

Distribution and characterization of kepone-resistant bacteria in the aquatic environment.  

PubMed

Effects of the chlorinated insecticide Kepone on the ecology of Chesapeake Bay and James River bacteria were studied. Kepone-resistant bacteria present in a given environment were found to reflect the degree of fecal and/or high organic pollution of the sampling sites, based on total numbers and generic composition of the populations of Kepone-resistant bacteria. The presence of Kepone-resistant bacteria was found to be correlated (alpha = 0.01) with total coliforms, fecal coliforms, and total aerobic viable heterotrophic bacteria, but not with Kepone concentration, since Kepone-resistant bacteria were present in locations where Kepone could not be detected by the analytical methods used in this study. Only gram-negative bacteria, predominantly Pseudomonas, Vibrio, and Aeromonas spp., were found to be resistant to >/=10 mug of Kepone per ml. Gram-positive bacteria, i.e., Bacillus and Corynebacterium spp., were generally sensitive to >/=0.1 mug of Kepone per ml. From results of cluster analysis of taxonomic data, we determined that characteristics of Kepone-resistant bacteria included: resistance to pesticides and heavy metals; degradation of oil; positive oxidase and catalase reactions; and nitrate reduction. From results of the ecological and taxonomic analyses, we conclude that Kepone resistance in estuarine bacteria is due to the physicochemical composition of the gram-negative cell wall and not prior exposure to Kepone. Therefore, the presence of Kepone-resistant bacteria cannot serve as an indicator of Kepone contamination in the aquatic environment where gram-negative bacteria are predominant. PMID:6155825

Orndorff, S A; Colwell, R R

1980-03-01

339

Distribution and Characterization of Kepone-Resistant Bacteria in the Aquatic Environment  

PubMed Central

Effects of the chlorinated insecticide Kepone on the ecology of Chesapeake Bay and James River bacteria were studied. Kepone-resistant bacteria present in a given environment were found to reflect the degree of fecal and/or high organic pollution of the sampling sites, based on total numbers and generic composition of the populations of Kepone-resistant bacteria. The presence of Kepone-resistant bacteria was found to be correlated (? = 0.01) with total coliforms, fecal coliforms, and total aerobic viable heterotrophic bacteria, but not with Kepone concentration, since Kepone-resistant bacteria were present in locations where Kepone could not be detected by the analytical methods used in this study. Only gram-negative bacteria, predominantly Pseudomonas, Vibrio, and Aeromonas spp., were found to be resistant to ?10 ?g of Kepone per ml. Gram-positive bacteria, i.e., Bacillus and Corynebacterium spp., were generally sensitive to ?0.1 ?g of Kepone per ml. From results of cluster analysis of taxonomic data, we determined that characteristics of Kepone-resistant bacteria included: resistance to pesticides and heavy metals; degradation of oil; positive oxidase and catalase reactions; and nitrate reduction. From results of the ecological and taxonomic analyses, we conclude that Kepone resistance in estuarine bacteria is due to the physicochemical composition of the gram-negative cell wall and not prior exposure to Kepone. Therefore, the presence of Kepone-resistant bacteria cannot serve as an indicator of Kepone contamination in the aquatic environment where gram-negative bacteria are predominant. PMID:6155825

Orndorff, S. A.; Colwell, R. R.

1980-01-01

340

Deep-red fluorescent imaging probe for bacteria  

PubMed Central

A versatile deep-red fluorescent imaging probe is described that is comprised of a bis(zinc(II)-dipicolylamine) targeting unit covalently attached to a pentamethine carbocyanine fluorophore with Cy5-like spectroscopic properties. A titration assay based on fluorescence resonance energy transfer is used to prove that the probe selectively associates with anionic vesicle membranes whose composition mimics bacterial cell membranes. Whole-body optical imaging experiments show that the probe associates with the surfaces of both Gram-positive and Gram-negative bacteria cells, and it can target the site of bacterial infection in a living mouse. In vivo accumulation at the infection site and subsequent clearance occurs more quickly than a structurally related near-infrared bis(zinc(II)-dipicolylamine) probe. The fact that the same deep-red probe molecule can be used for spectroscopic assays, cell microscopy, and in vivo imaging studies, is an important and attractive technical feature. PMID:22424976

White, Alexander G.; Gray, Brian D.; Pak, Koon Yan; Smith, Bradley D.

2012-01-01

341

Protein signaling via type III secretion pathways in phytopathogenic bacteria  

E-print Network

109 Protein signaling via type III secretion pathways in phytopathogenic bacteria Mary Beth Mudgett secretion pathway has revealed new mechanisms by which phytopathogenic bacteria infect plants are continually exposed to a number of potentially pathogenic bacteria. Phytopathogenic bacteria, in general

Mudgettt, Mary Beth

342

Oligotrophic bacteria isolated from clinical materials.  

PubMed Central

Oligotrophic bacteria (oligotrophs) are microorganisms that grow in extremely nutritionally deficient conditions in which the concentrations of organic substances are low. Many oligotrophic bacteria were isolated from clinical materials including urine, sputum, swabbings of the throat, vaginal discharges, and others. Seventy-seven strains of oligotrophic bacteria from 871 samples of clinical material were isolated. A relatively higher frequency of isolation of oligotrophic bacteria was shown in drainage, sputum, and throat specimens. Eleven strains of the obligate oligotrophic bacteria recovered showed scant growth on enriched medium, blood agar, and nutrient agar. Oligotrophic bacteria were isolated from a variety of materials but were not found in routine bacteriologic examinations in the hospital laboratory. The clinical significance of such oligotrophic bacteria is uncertain. PMID:7714215

Tada, Y; Ihmori, M; Yamaguchi, J

1995-01-01

343

Influence of Bentonite Particles on the Transport and Deposition Behavior of Bacteria in Porous Media  

NASA Astrophysics Data System (ADS)

The influence of clay particles on the transport and deposition behavior of bacteria in irregular quartz sand was examined by direct comparison of both breakthrough curves and retained profiles with clay particles in bacteria suspension versus those without clay particles. Two representative cell types, Gram-negative strain E.coli DH5? and Gram-positive strain Bacillus subtilis were utilized to systematically determine the influence of clay particles (bentonite) on cell transport behavior. Packed column experiments for both cell types were conducted in both NaCl (5 and 25 mM ionic strengths) and CaCl2 (5 mM ionic strength) solutions at pH 6.0. The breakthrough plateaus with bentonite in solutions (30 mg L-1 and 50 mg L-1) were lower than those without bentonite for both cell types under all examined conditions, indicating that bentonite in solutions decreased cell transport in porous media regardless of cell types (Gram-negative or Gram-positive) and solution chemistry (ionic strength and ion valence). The enhanced cell deposition with bentonite particles was mainly observed at segments near to column inlet, retained profiles for both cell types with bentonite particles therefore were steeper relative to those without bentonite. The increased cell deposition with bentonite observed in NaCl solutions was mainly attributed to the co-deposition of bacteria with bentonite particles whereas, in addition to co-deposition of bacteria with bentonite, the bacteria-bentonite-bacteria cluster formed in suspensions also contributed to the increased deposition of bacteria with bentonite in CaCl2 solution.

Yang, Haiyan; Tong, Meiping; Kim, Hyunjung

2013-04-01

344

RNA-mediated regulation in Gram-positive pathogens: an overview punctuated with examples from the group A Streptococcus.  

PubMed

RNA-based mechanisms of regulation represent a ubiquitous class of regulators that are associated with diverse processes including nutrient sensing, stress response, modulation of horizontal gene transfer, and virulence factor expression. While better studied in Gram-negative bacteria, the literature is replete with examples of the importance of RNA-mediated regulatory mechanisms to the virulence and fitness of Gram-positives. Regulatory RNAs are classified as cis-acting, e.g. riboswitches, which modulate the transcription, translation, or stability of co-transcribed RNA, or trans-acting, e.g. small regulatory RNAs, which target separate mRNAs or proteins. The group A Streptococcus (GAS, Streptococcus pyogenes) is a Gram-positive bacterial pathogen from which several regulatory RNA mechanisms have been characterized. The study of RNA-mediated regulation in GAS has uncovered novel concepts with respect to how small regulatory RNAs may positively regulate target mRNA stability, and to how CRISPR RNAs are processed from longer precursors. This review provides an overview of RNA-mediated regulation in Gram-positive bacteria, and is highlighted with specific examples from GAS research. The key roles that these systems play in regulating bacterial virulence are discussed and future perspectives outlined. PMID:25091277

Miller, Eric W; Cao, Tram N; Pflughoeft, Kathryn J; Sumby, Paul

2014-10-01

345

Current status and emerging role of glutathione in food grade lactic acid bacteria  

PubMed Central

Lactic acid bacteria (LAB) have taken centre stage in perspectives of modern fermented food industry and probiotic based therapeutics. These bacteria encounter various stress conditions during industrial processing or in the gastrointestinal environment. Such conditions are overcome by complex molecular assemblies capable of synthesizing and/or metabolizing molecules that play a specific role in stress adaptation. Thiols are important class of molecules which contribute towards stress management in cell. Glutathione, a low molecular weight thiol antioxidant distributed widely in eukaryotes and Gram negative organisms, is present sporadically in Gram positive bacteria. However, new insights on its occurrence and role in the latter group are coming to light. Some LAB and closely related Gram positive organisms are proposed to possess glutathione synthesis and/or utilization machinery. Also, supplementation of glutathione in food grade LAB is gaining attention for its role in stress protection and as a nutrient and sulfur source. Owing to the immense benefits of glutathione, its release by probiotic bacteria could also find important applications in health improvement. This review presents our current understanding about the status of glutathione and its role as an exogenously added molecule in food grade LAB and closely related organisms. PMID:22920585

2012-01-01

346

Accentuate the (Gram) positive Victor Nizet  

E-print Network

, resisting local mucosal immune responses, or allowing SPN to outcom- pete other members of the local flora of the leading Gram-positive bacterial pathogens and their interactions with the human immune system. Many new colonizes the human host without causing symptoms (carrier state) or generates milder, self- limited mucosal

Nizet, Victor

347

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

348

Resolving chromosome segregation in bacteria.  

PubMed

Bacterial chromosomes are evenly distributed between daughter cells, however no equivalent eukaryotic mitotic apparatus has been identified yet. Nevertheless, an advance in our understanding of the dynamics of the bacterial chromosome has been accomplished in recent years by adopting fluorescence microscopy techniques to visualize living bacterial cells. Here, some of the most recent studies that yield new insights into the nature of bacterial chromosome dynamics are described. In addition, we review in detail the current models that attempt to illuminate the mechanism of chromosome segregation in bacteria and discuss the possibility that a bacterial mitotic apparatus does indeed exist. PMID:16983190

Hazan, Ronen; Ronen, Hazan; Ben-Yehuda, Sigal; Sigal, Ben-Yehuda

2006-01-01

349

Sampling for Bacteria in Wells  

E-print Network

collecting the sample. 5. Run the water at full flow for five minutes to clear the water lines and bring in fresh water. 6. Reduce the flow to a pencil stream to prepare for sampling. 7. Carefully open the sterile bottle. Hold the cap in one hand... immediately after collecting water sample. Refrigerate the sample and transport it to the laborato- ry (in an ice chest) as soon after collection as possible (six hours is best, but up to 30 hours). Many labs will not accept bacteria samples on Friday so check...

Lesikar, Bruce J.

2001-11-15

350

Genetic manipulation of acidophilic bacteria  

SciTech Connect

Thiobacillus ferrooxidans is important in leaching of metals from mineral ores and in the removal of pyritic sulfur from coal. It is also intimately involved in production of acid mine drainage. Other acidophilic bacteria, including members of the genus Acidiphilium, are usually present in the same environments as T. ferrooxidans, and there is evidence to suggest that these acidophilic heterotrophs may increase the rate of T. ferrooxidans' attack on inorganic sulfides. Our laboratory is studying the genetic characteristics of these acidophilic bacteria and developing techniques for introducing desirable genes into them. Several endogenous plasmids from Acidiphilium strains have been cloned into E. coli vectors. Some of the resulting plasmids are able to confer antibiotic resistance to Acidiphilium after transformation by electroporation. In addition, a broad-host range plasmid conferring resistance to tetracycline has been introduced into Acidiphilium strains by electroporation. This same plasmid, has also been transferred to Acidiphilium from E. coli directly by conjugation. A temperate bacteriophage which infects a number of Acidiphilium isolates has been discovered and partially characterized. It has a lambdoid morphology and a genome of approximately 97 kb, comprised of double-stranded DNA which is probably modified. 16 refs., 2 figs., 4 tabs.

Ward, T.E.; Rowland, M.L.; Glenn, A.W.; Watkins, C.S.; Bruhn, D.F.; Bulmer, D.; Roberto, F.F.

1989-01-01

351

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

352

Distribution and Diversity of Symbiotic Thermophiles, Symbiobacterium thermophilum and Related Bacteria, in Natural Environments  

PubMed Central

Symbiobacterium thermophilum is a tryptophanase-positive thermophile which shows normal growth only in coculture with its supporting bacteria. Analysis of the 16S rRNA gene (rDNA) indicated that the bacterium belongs to a novel phylogenetic branch at the outermost position of the gram-positive bacterial group without clustering to any other known genus. Here we describe the distribution and diversity of S. thermophilum and related bacteria in the environment. Thermostable tryptophanase activity and amplification of the specific 16S rDNA fragment were effectively employed to detect the presence of Symbiobacterium. Enrichment with kanamycin raised detection sensitivity. Mixed cultures of thermophiles containing Symbiobacterium species were frequently obtained from compost, soil, animal feces, and contents in the intestinal tracts, as well as feeds. Phylogenetic analysis and denaturing gradient gel electrophoresis of the specific 16S rDNA amplicons revealed a diversity of this group of bacteria in the environment. PMID:11525967

Ueda, Kenji; Ohno, Michiyo; Yamamoto, Kaori; Nara, Hanae; Mori, Yujiro; Shimada, Masafumi; Hayashi, Masahiko; Oida, Hanako; Terashima, Yuko; Nagata, Mitsuyo; Beppu, Teruhiko

2001-01-01

353

Prevalence of potentially pathogenic bacteria as genital pathogens in dairy cattle.  

PubMed

Bacteria on the genital mucosa have been studied less in healthy, non-puerperal cows than in cows with puerperal endometritis. We have thus analysed bacteria in swabs from the vagina and cervix of post-puerperal cattle (n = 644). Out of the animals, 6.8% had aborted within the last 12 months, 2.6% and 11.6% showed signs of vaginitis and endometritis, respectively. In 17.2% of cervical swabs pathogenic gram-positive and in 11.5% pathogenic gram-negative bacteria were found. Arcanobacterium pyogenes was isolated from 41.3% of cows with endometritis and from 3.5% without endometritis (p < 0.05). From 12.5% of cows with abortion but from no cow without abortion, Staphylococcus aureus was recovered (p < 0.05). Out of 383 vaginal swabs, 88.3% were positive. In 3.4% of swabs pathogenic gram-positive and in 16.7% pathogenic gram-negative microorganisms were found. The percentage of positive vaginal swabs did not differ between pregnant and non-pregnant animals. In the genital tract, the percentage of swabs positive for normal mucosal bacteria decreased from caudally to cranially (p < 0.05). Pathogenic bacteria were found more often in cervical than in vaginal swabs (p < 0.05). In conclusion, bacteria on the vaginal and cervical mucosa in cattle involve a wide range of species. In animals without endometritis or vaginitis, colonization of the mucosa rather than infection has to be assumed. PMID:18537907

Petit, T; Spergser, J; Rosengarten, R; Aurich, J

2009-02-01

354

Microbicidal activity of tripotassium phosphate and fatty acids toward spoilage and pathogenic bacteria associated with poultry.  

PubMed

The ability of solutions of tripotassium phosphate (TPP) and fatty acids (lauric and myristic acids) to reduce populations of spoilage and pathogenic microorganisms associated with processed poultry was examined. In vitro studies were conducted with cultures of bacteria (Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Typhimurium, and Staphylococcus aureus) and yeasts (Candida ernobii and Yarrowia lipolytica). Cultures of the bacteria and yeasts were suspended in solutions of TPP or mixtures of TPP with lauric or myristic acid and mixed for 5 min. Viable numbers (log CFU per milliliter) in the suspensions were enumerated on microbiological agar. Results indicated that TPP solutions are highly bactericidal toward gram-negative bacteria and that mixtures of TPP and fatty acids are highly microbicidal toward gram-negative bacteria, gram-positive bacteria, and yeasts. The microbicidal activity of mixtures of TPP and fatty acids toward the native bacterial flora of skin of processed broiler carcasses was also examined. Skin samples were washed in mixtures of TPP and fatty acid, and the populations of total aerobic bacteria, campylobacters, enterococci, E. coli, lactic acid bacteria, pseudomonads, staphylococci, and yeasts in the skin rinsates were enumerated on the appropriate microbiological media. Results indicated that washing the skin in mixtures of TPP and fatty acids produced significant reductions in the number of aerobic bacteria, campylobacters, E. coli, pseudomonads, and yeasts recovered from skin rinsates, but there was no significant reduction in the populations of enterococci, lactic acid bacteria, or staphylococci. These findings indicate that mixtures of TPP and fatty acids possess microbicidal activity against several microorganisms associated with processed poultry and that these solutions could be useful as microbicides to reduce the populations of some bacteria and yeasts associated with some poultry processing operations. PMID:16013388

Hinton, Arthur; Ingram, Kimberly D

2005-07-01

355

In vitro activity of Bay Y3118 against anaerobic bacteria.  

PubMed Central

The antimicrobial activity of a new quinolone, Bay Y3118, was determined against 326 strains of anaerobic bacteria and compared with the activities of ampicillin-sulbactam, cefotetan, clindamycin, imipenem, metronidazole, and sparfloxacin. The National Committee for Clinical Laboratory Standards-approved Wadsworth agar dilution technique with Brucella-laked blood agar was used throughout the study. Breakpoints used to determine the percent susceptible were 2 micrograms/ml for Bay Y3118 and sparfloxacin, 4 micrograms/ml for clindamycin, 8 micrograms/ml for imipenem, 16 micrograms/ml for metronidazole and ampicillin-sulbactam, and 32 micrograms/ml for cefotetan. Species tested included Bacteroides fragilis (57 strains), other B. fragilis group species (79 strains), Bacteroides gracilis (10 strains), other Bacteroides spp. (9 strains), Prevotella spp. (30 strains), Porphyromonas spp. (9 strains), Fusobacterium spp. (36 strains), Bilophila wadsworthia (14 strains), Clostridium spp. (36 strains), Peptostreptococcus spp. (20 strains), and gram-positive non-spore-forming rods (26 strains). Bay Y3118 inhibited all but 1 of 326 anaerobic bacteria tested at the breakpoint level or lower. PMID:8285647

Wexler, H M; Molitoris, E; Finegold, S M

1993-01-01

356

Toxicological effect of ZnO nanoparticles based on bacteria.  

PubMed

Streptococcus agalactiae and Staphylococcus aureus are two pathogenetic agents of several infective diseases in humans. Biocidal effects and cellular internalization of ZnO nanoparticles (NPs) on two bacteria are reported, and ZnO NPs have a good bacteriostasis effect. ZnO NPs were synthesized in the EG aqueous system through the hydrolysis of ionic Zn2+ salts. Particle size and shape were controlled by the addition of the various surfactants. Bactericidal tests were performed in an ordinary broth medium on solid agar plates and in liquid systems with different concentrations of ZnO NPs. The biocidal action of ZnO materials was studied by transmission electron microscopy of bacteria ultrathin sections. The results confirmed that bactericidal cells were damaged after ZnO NPs contacted with them, showing both gram-negative membrane and gram-positive membrane disorganization. The surface modification of ZnO NPs causes an increase in membrane permeability and the cellular internalization of these NPs whereas there is a ZnO NP structure change inside the cells. PMID:18341364

Huang, Zhongbing; Zheng, Xu; Yan, Danhong; Yin, Guangfu; Liao, Xiaoming; Kang, Yunqing; Yao, Yadong; Huang, Di; Hao, Baoqing

2008-04-15

357

Lactic Acid Bacteria Convert Human Fibroblasts to Multipotent Cells  

PubMed Central

The human gastrointestinal tract is colonized by a vast community of symbionts and commensals. Lactic acid bacteria (LAB) form a group of related, low-GC-content, gram-positive bacteria that are considered to offer a number of probiotic benefits to general health. While the role of LAB in gastrointestinal microecology has been the subject of extensive study, little is known about how commensal prokaryotic organisms directly influence eukaryotic cells. Here, we demonstrate the generation of multipotential cells from adult human dermal fibroblast cells by incorporating LAB. LAB-incorporated cell clusters are similar to embryoid bodies derived from embryonic stem cells and can differentiate into endodermal, mesodermal, and ectodermal cells in vivo and in vitro. LAB-incorporated cell clusters express a set of genes associated with multipotency, and microarray analysis indicates a remarkable increase of NANOG, a multipotency marker, and a notable decrease in HOX gene expression in LAB-incorporated cells. During the cell culture, the LAB-incorporated cell clusters stop cell division and start to express early senescence markers without cell death. Thus, LAB-incorporated cell clusters have potentially wide-ranging implications for cell generation, reprogramming, and cell-based therapy. PMID:23300571

Ohta, Kunimasa; Kawano, Rie; Ito, Naofumi

2012-01-01

358

Mechanism for longitudinal growth of rod-shaped bacteria  

NASA Astrophysics Data System (ADS)

The peptidoglycan (PG) cell wall along with MreB proteins are major determinants of shape in rod-shaped bacteria. However the mechanism guiding the growth of this elastic network of cross-linked PG (sacculus) that maintains the integrity and shape of the rod-shaped cell remains elusive. We propose that the known anisotropic elasticity and anisotropic loading, due to the shape and turgor pressure, of the sacculus is sufficient to direct small gaps in the sacculus to elongate around the cell, and that subsequent repair leads to longitudinal growth without radial growth. We computationally show in our anisotropically stressed anisotropic elasticity model small gaps can extend stably in the circumferential direction for the known elasticity of the sacculus. We suggest that MreB patches that normally propagate circumferentially [1], are associated with these gaps and are steered with this common mechanism. This basic picture is unchanged in Gram positive and Gram negative bacteria. We also show that small changes of elastic properties can in fact lead to bi-stable propagation of gaps, both longitudinal and circumferential, that can explain the bi-stability in patch movement observed in ?mbl ?mreb mutants.[4pt] [1] J. Dom'inguez-Escobar et al., Science

Taneja, Swadhin; Levitan, Ben; Rutenberg, Andrew

2013-03-01

359

Spectroscopic diagnostics for bacteria in biologic sample  

DOEpatents

A method to analyze and diagnose specific bacteria in a biologic sample using spectroscopy is disclosed. The method includes obtaining the spectra of a biologic sample of a non-infected patient for use as a reference, subtracting the reference from the spectra of an infected sample, and comparing the fingerprint regions of the resulting differential spectrum with reference spectra of bacteria in saline. Using this diagnostic technique, specific bacteria can be identified sooner and without culturing, bacteria-specific antibiotics can be prescribed sooner, resulting in decreased likelihood of antibiotic resistance and an overall reduction of medical costs.

El-Sayed, Mostafa A. (Atlanta, GA); El-Sayed, Ivan H. (Somerville, MA)

2002-01-01

360

Survival of soil bacteria during prolonged desiccation.  

NASA Technical Reports Server (NTRS)

A determination was made of the kinds and numbers of bacteria surviving when two soils were maintained in the laboratory under dry conditions for more than half a year. Certain non-spore-forming bacteria were found to survive in the dry condition for long periods. A higher percentage of drought-tolerant than drought-sensitive bacteria was able to grow at low water activities. When they were grown in media with high salt concentrations, bacteria generally became more tolerant of prolonged drought and they persisted longer. The percent of cells in a bacterial population that remained viable when exposed to drought stress varied with the stage of growth.

Chen, M.; Alexander, M.

1973-01-01

361

Discrimination of selected species of pathogenic bacteria using near-infrared Raman spectroscopy and principal components analysis  

NASA Astrophysics Data System (ADS)

A method, based on Raman spectroscopy, for identification of different microorganisms involved in bacterial urinary tract infections has been proposed. Spectra were collected from different bacterial colonies (Gram-negative: Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa and Enterobacter cloacae, and Gram-positive: Staphylococcus aureus and Enterococcus spp.), grown on culture medium (agar), using a Raman spectrometer with a fiber Raman probe (830 nm). Colonies were scraped from the agar surface and placed on an aluminum foil for Raman measurements. After preprocessing, spectra were submitted to a principal component analysis and Mahalanobis distance (PCA/MD) discrimination algorithm. We found that the mean Raman spectra of different bacterial species show similar bands, and S. aureus was well characterized by strong bands related to carotenoids. PCA/MD could discriminate Gram-positive bacteria with sensitivity and specificity of 100% and Gram-negative bacteria with sensitivity ranging from 58 to 88% and specificity ranging from 87% to 99%.

de Siqueira e Oliveira, Fernanda SantAna; Giana, Hector Enrique; Silveira, Landulfo

2012-10-01

362

Discrimination of selected species of pathogenic bacteria using near-infrared Raman spectroscopy and principal components analysis  

NASA Astrophysics Data System (ADS)

It has been proposed a method based on Raman spectroscopy for identification of different microorganisms involved in bacterial urinary tract infections. Spectra were collected from different bacterial colonies (Gram negative: E. coli, K. pneumoniae, P. mirabilis, P. aeruginosa, E. cloacae and Gram positive: S. aureus and Enterococcus sp.), grown in culture medium (Agar), using a Raman spectrometer with a fiber Raman probe (830 nm). Colonies were scraped from Agar surface placed in an aluminum foil for Raman measurements. After pre-processing, spectra were submitted to a Principal Component Analysis and Mahalanobis distance (PCA/MD) discrimination algorithm. It has been found that the mean Raman spectra of different bacterial species show similar bands, being the S. aureus well characterized by strong bands related to carotenoids. PCA/MD could discriminate Gram positive bacteria with sensitivity and specificity of 100% and Gram negative bacteria with good sensitivity and high specificity.

de Siqueira e Oliveira, Fernanda S.; Giana, Hector E.; Silveira, Landulfo, Jr.

2012-03-01

363

Lactic acid bacteria as probiotics.  

PubMed

A number of Lactobacillus species, Bifidobacterium sp, Saccharomyces boulardii, and some other microbes have been proposed as and are used as probiotic strains, i.e. live microorganisms as food supplement in order to benefit health. The health claims range from rather vague as regulation of bowel activity and increasing of well-being to more specific, such as exerting antagonistic effect on the gastroenteric pathogens Clostridium difficile, Campylobacter jejuni, Helicobacter pylori and rotavirus, neutralising food mutagens produced in colon, shifting the immune response towards a Th2 response, and thereby alleviating allergic reactions, and lowering serum cholesterol (Tannock, 2002). Unfortunately, most publications are case reports, uncontrolled studies in humans, or reports of animal or in vitro studies. Whether or not the probiotic strains employed shall be of human origin is a matter of debate but this is not a matter of concern, as long as the strains can be shown to survive the transport in the human gastrointestinal (GI) tract and to colonise the human large intestine. This includes survival in the stressful environment of the stomach - acidic pH and bile - with induction of new genes encoding a number of stress proteins. Since the availability of antioxidants decreases rostrally in the GI tract production of antioxidants by colonic bacteria provides a beneficial effect in scavenging free radicals. LAB strains commonly produce antimicrobial substance(s) with activity against the homologous strain, but LAB strains also often produce microbicidal substances with effect against gastric and intestinal pathogens and other microbes, or compete for cell surface and mucin binding sites. This could be the mechanism behind reports that some probiotic strains inhibit or decrease translocation of bacteria from the gut to the liver. A protective effect against cancer development can be ascribed to binding of mutagens by intestinal bacteria, reduction of the enzymes beta-glucuronidase and beta-glucosidase, and deconjugation of bile acids, or merely by enhancing the immune system of the host. The latter has attracted considerable interest, and LAB have been tested in several clinical trials in allergic diseases. Characteristics ascribed to a probiotic strain are in general strain specific, and individual strains have to be tested for each property. Survival of strains during production, packing and storage of a viable cell mass has to be tested and declared. PMID:16875422

Ljungh, Asa; Wadström, Torkel

2006-09-01

364

Modeling Political Populations with Bacteria  

NASA Astrophysics Data System (ADS)

Results from lattice-based simulations of micro-environments with heterogeneous nutrient resources reveal that competition between wild-type and GASP rpoS819 strains of E. Coli offers mutual benefit, particularly in nutrient deprived regions. Our computational model spatially maps bacteria populations and energy sources onto a set of 3D lattices that collectively resemble the topology of North America. By implementing Wright-Fishcer re- production into a probabilistic leap-frog scheme, we observe populations of wild-type and GASP rpoS819 cells compete for resources and, yet, aid each other's long term survival. The connection to how spatial political ideologies map in a similar way is discussed.

Cleveland, Chris; Liao, David

2011-03-01

365

MICROBIOLOGY: How Bacteria Change Gear  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Many species of bacteria form biofilms, slimy carpets a fraction of a millimeter thick that appear on rocks, leaves, pipes, teeth--pretty much any place that has a supply of nutrients and water. Cells must first attach to a surface, which in many species requires swimming propelled by rotating helical flagella (1). Two things typically happen next. Cells stop expressing genes that encode components of the flagellum, and they secrete a sticky matrix of polysaccharides that holds them together on the surface (2). Once at a surface, swimming may be a hindrance rather than a help, and an inverse relationship between swimming and attachment has been seen in many diverse species (3). Bacterial motility is arrested when a protein that acts as a clutch disables rotation of the flagellar motor.

Richard M. Berry (University of Oxford;Department of Physics, Clarendon Lab); Judith P. Armitage (University of Oxford;Department of Biochemistry & Oxford Centre for Integrative Systems Biology)

2008-06-20

366

Taurolidine Antiadhesive Properties on Interaction with E. coli; Its Transformation in Biological Environment and Interaction with Bacteria Cell Wall  

Microsoft Academic Search

The taurine amino-acid derivative, taurolidine, bis-(1,1-dioxoperhydro-1,2,4-thiabiazinyl–4)methane, shows broad antibacterial action against gram-positive and gram-negative bacteria, mycobacteria and some clinically relevant fungi. It inhibits, in vitro, the adherence of Escherichia coli and Staphylococcus aureus to human epithelial and fibroblast cells. Taurolidine is unstable in aqueous solution and breaks down into derivatives which are thought to be responsible for the biological activity.

Francesco Caruso; James W. Darnowski; Cristian Opazo; Alexander Goldberg; Nina Kishore; Elin S. Agoston; Miriam Rossi; Jörg Hoheisel

2010-01-01

367

Antibiotic Activity of Xenorhabdus spp., Bacteria Symbiotically Associated with Insect Pathogenic Nematodes of the Families Heterorhabditidae and Steinernematidae  

Microsoft Academic Search

A wide range of micro-organisms, including yeasts, was found to be inhibited by the primary form of Xenorhabdus spp., but not by the secondary form. Only one Xenorhabdus strain, the symbiont of Neoaplectana glaseri, did not inhibit any of the micro-organisms tested; it is suggested that this strain may not have been isolated in the primary form. Gram-positive bacteria were

R. J. Akhurst

1982-01-01

368

Broth Disk Elution Method for Anaerobic Bacteria: A Collaborative Study to Assess Its Reliability for Clinical Purposes  

Microsoft Academic Search

A collaborative study involving seven laboratories was undertaken to evaluate the reproducibility and the reliability of the broth disk elution test against anaerobic bacteria by comparing with the reference agar dilution method. A two breakpoint broth test was also evaluated. Assays were performed using the same testing conditions (i.e. medium, temperature, atmosphere and incubation time). One hundred Gram-negative and Gram-positive

Hebe Bianchini; Liliana Fernández Canigia; Silvia C Predari; Raquel Rollet; Mirta Litterio; Pablo Berestein; Liliana Castello; Ana De Martino; Graciela Greco; Nélida Hardie

1997-01-01

369

Microbial Quality and Direct PCR Identification of Lactic Acid Bacteria and Nonpathogenic Staphylococci from Artisanal Low-Acid Sausages  

Microsoft Academic Search

Detection of six species of lactic acid bacteria and six species of gram-positive catalase-positive cocci from low-acid fermented sausages (fuets and chorizos) was assessed by species-specific PCR. Without enrichment, Lactobacillus sakei and Lactobacillus curvatus were detected in 11.8% of the samples, and Lactobacillus plantarum and Staphylococcus xylosus were detected in 17.6%. Enriched samples allowed the detection of L. sakei and

T. Aymerich; B. Martin; M. Garriga; M. Hugas

2003-01-01

370

The isolation, identification of sludge-lysing thermophilic bacteria and its utilization in solubilization for excess sludge  

Microsoft Academic Search

A novel strain of thermophilic bacteria with a highly efficient sludge dissolution performance was isolated from garden soil at 65°C in this study. The colony morphology, physiological and biochemical characteristics of the strain were investigated. The results showed that the strain was Gram-positive, small rod-shaped, sporulating and secreted extracellular enzymes (protease and amylase). The 16S rDNA analysis demonstrated that this

Ying Tang; Yong-lin Yang; Xiao-ming Li; Qi Yang; Dong-bo Wang; Guang-ming Zeng

2011-01-01

371

The isolation, identification of sludge-lysing thermophilic bacteria and its utilization in solubilization for excess sludge  

Microsoft Academic Search

A novel strain of thermophilic bacteria with a highly efficient sludge dissolution performance was isolated from garden soil at 65°C in this study. The colony morphology, physiological and biochemical characteristics of the strain were investigated. The results showed that the strain was Gram-positive, small rod-shaped, sporulating and secreted extracellular enzymes (protease and amylase). The 16S rDNA analysis demonstrated that this

Ying Tang; Yong-lin Yang; Xiao-ming Li; Qi Yang; Dong-bo Wang; Guang-ming Zeng

2012-01-01

372

Phylogenetic Diversity of Lactic Acid Bacteria Associated with Paddy Rice Silage as Determined by 16S Ribosomal DNA Analysis  

Microsoft Academic Search

A total of 161 low-GC-content gram-positive bacteria isolated from whole-crop paddy rice silage were classified and subjected to phenotypic and genetic analyses. Based on morphological and biochemical char- acters, these presumptive lactic acid bacterium (LAB) isolates were divided into 10 groups that included members of the genera Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, and Weissella. Analysis of the 16S ribosomal DNA

Saïd Ennahar; Yimin Cai; Yasuhito Fujita

2003-01-01

373

Analysis of the composition and characteristics of culturable endophytic bacteria within subnival plants of the Tianshan Mountains, northwestern China.  

PubMed

This study first described the composition and characteristics of culturable endophytic bacteria isolated from wild alpine-subnival plant species growing under extreme environmental conditions (i.e., on the border of a glacier with frequently fluctuating and freezing temperatures, strong wind, and high ultraviolet radiation). Using a cultivation-dependent approach and 16S rRNA gene amplification techniques, 93 bacterial isolates showing different phenotypic properties were obtained from 20 different subnival plant species, of which gram-positive bacteria (61.5%), psychrotolerant bacteria (67.3%), and pigmented isolates (70.9%) accounted for a large proportion. All these characteristics of endophytes were closely related to the survival environment of their host plants and were in good agreement with microbes occurring in other cold environments. Phylogenetic analysis indicated that the endophytic isolates consisted of five phylogenetic groups comprising ?-proteobacteria, ?-proteobacteria, the high G+C content gram-positive bacteria, the low G+C content gram-positive bacteria, and Flavobacterium-Bacteroides-Cytophaga. The largest generic diversity was found in the HGC group, while Clavibacter, Agreia, Rhodococcus, Sphingomonas, and Pseudomonas were the most prevalent genera. Of all isolates, 46.4% showed a high sequence similarity (98-100%) to strains discovered from other cold environments such as glaciers, tundra, and polar seas. Furthermore, 36.4% of the isolates produced Indole-3-acetic acid and 76.3% were able to solubilize mineral phosphate, which revealed that endophytic bacteria with multiple physiological functions were abundant and widespread in subnival plants. These results are essential for understanding the ecological roles of endophytes and as a foundation for further studying the interactions with plants and environment. PMID:21061126

Sheng, Hong Mei; Gao, Hong Shan; Xue, Lin Gui; Ding, Shuo; Song, Chun Li; Feng, Hu Yuan; An, Li Zhe

2011-03-01

374

Fighting infections due to multidrug-resistant Gram-positive pathogens.  

PubMed

Growing bacterial resistance in Gram-positive pathogens means that what were once effective and inexpensive treatments for infections caused by these bacteria are now being seriously questioned, including penicillin and macrolides for use against pneumococcal infections and-in hospitals-oxacillin for use against staphylococcal infections. As a whole, multidrug-resistant (MDR) Gram-positive pathogens are rapidly becoming an urgent and sometimes unmanageable clinical problem. Nevertheless, and despite decades of research into the effects of antibiotics, the actual risk posed to human health by antibiotic resistance has been poorly defined; the lack of reliable data concerning the outcomes resulting from antimicrobial resistance stems, in part, from problems with study designs and the methods used in resistence determination. Surprisingly little is known, too, about the actual effectiveness of the many types of intervention aimed at controlling antibiotic resistance. New antibiotics active against MDR Gram-positive pathogens have been recently introduced into clinical practice, and the antibiotic pipeline contains additional compounds at an advanced stage of development, including new glycopeptides, new anti-methicillin-resistant Staphylococcus aureus (MRSA) beta-lactams, and new diaminopyrimidines. Many novel antimicrobial agents are likely to be niche products, endowed with narrow antibacterial spectra and/or targeted at specific clinical problems. Therefore, an important educational goal will be to change the current, long-lasting attitudes of both physicians and customers towards broad-spectrum and multipurpose compounds. Scientific societies, such as the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), must play a leading role in this process. PMID:19335367

Cornaglia, G

2009-03-01

375

Recognition of U-rich RNA by Hfq from the Gram-positive pathogen Listeria monocytogenes  

PubMed Central

Hfq is a post-transcriptional regulator that binds U- and A-rich regions of sRNAs and their target mRNAs to stimulate their annealing in order to effect translation regulation and, often, to alter their stability. The functional importance of Hfq and its RNA-binding properties are relatively well understood in Gram-negative bacteria, whereas less is known about the RNA-binding properties of this riboregulator in Gram-positive species. Here, we describe the structure of Hfq from the Gram-positive pathogen Listeria monocytogenes in its RNA-free form and in complex with a U6 oligoribonucleotide. As expected, the protein takes the canonical hexameric toroidal shape of all other known Hfq structures. The U6 RNA binds on the “proximal face” in a pocket formed by conserved residues Q9, N42, F43, and K58. Additionally residues G5 and Q6 are involved in protein-nucleic and inter-subunit contacts that promote uracil specificity. Unlike Staphylococcus aureus (Sa) Hfq, Lm Hfq requires magnesium to bind U6 with high affinity. In contrast, the longer oligo-uridine, U16, binds Lm Hfq tightly in the presence or absence of magnesium, thereby suggesting the importance of additional residues on the proximal face and possibly the lateral rim in RNA interaction. Intrinsic tryptophan fluorescence quenching (TFQ) studies reveal, surprisingly, that Lm Hfq can bind (GU)3G and U6 on its proximal and distal faces, indicating a less stringent adenine-nucleotide specificity site on the distal face as compared to the Gram-positive Hfq proteins from Sa and Bacillus subtilis and suggesting as yet uncharacterized RNA-binding modes on both faces. PMID:25150227

Kovach, Alexander R.; Hoff, Kirsten E.; Canty, John T.; Orans, Jillian

2014-01-01

376

Multidrug-Resistance and Toxic Metal Tolerance of Medically Important Bacteria Isolated from an Aquaculture System  

PubMed Central

The use of antimicrobials and toxic metals should be considered carefully in aquaculture and surrounding environments. We aimed to evaluate medically relevant bacteria in an aquaculture system and their susceptibility to antimicrobials and toxic metals. Selective cultures for enterobacteria (ENT), non-fermenting Gram-negative rods (NFR) and Gram-positive cocci (GPC) were obtained from water samples collected in two different year seasons. The isolated bacteria were biochemically identified and antimicrobial and toxic metal susceptibility patterns were determined. Overall, 407 representative strains were recovered. In general, bacteria isolated from fish ponds showed higher multiple antibiotic resistance indices when compared to those isolated from a water-fed canal. Resistance to penicillin and azithromycin was observed more frequently in the GPC group, whereas resistance to ampicillin and ampicillin/sulbactam or gentamicin was observed more frequently in the ENT and NFR groups, respectively. All the isolated bacteria were tolerant to nickel, zinc, chromium and copper at high levels (?1,024 ?g mL?1), whereas tolerance to cadmium and mercury varied among the isolated bacteria (2–1,024 ?g mL?1). Multidrug-resistant bacteria were more frequent and diverse in fish ponds than in the water-fed canal. A positive correlation was observed between antimicrobial resistance and metal tolerance. The data point out the need for water treatment associated with the aquaculture system. PMID:22972388

Resende, Juliana Alves; Silva, Vania L.; Fontes, Claudia Oliveira; Souza-Filho, Job Alves; de Oliveira, Tamara Lopes Rocha; Coelho, Cintia Marques; Cesar, Dioneia Evangelista; Diniz, Claudio Galuppo

2012-01-01

377

Current Perspectives on Viable but Non-Culturable (VBNC) Pathogenic Bacteria.  

PubMed

Under stress conditions, many species of bacteria enter into starvation mode of metabolism or a physiologically viable but non-culturable (VBNC) state. Several human pathogenic bacteria have been reported to enter into the VBNC state under these conditions. The pathogenic VBNC bacteria cannot be grown using conventional culture media, although they continue to retain their viability and express their virulence. Though there have been debates on the VBNC concept in the past, several molecular studies have shown that not only can the VBNC state be induced under in vitro conditions but also that resuscitation from this state is possible under appropriate conditions. The most notable advance in resuscitating VBNC bacteria is the discovery of resuscitation-promoting factor (Rpf), which is a bacterial cytokines found in both Gram-positive and Gram-negative organisms. VBNC state is a survival strategy adopted by the bacteria, which has important implication in several fields, including environmental monitoring, food technology, and infectious disease management; and hence it is important to investigate the association of bacterial pathogens under VBNC state and the water/foodborne outbreaks. In this review, we describe various aspects of VBNC bacteria, which include their proteomic and genetic profiles under the VBNC state, conditions of resuscitation, methods of detection, antibiotic resistance, and observations on Rpf. PMID:25133139

Ramamurthy, Thandavarayan; Ghosh, Amit; Pazhani, Gururaja P; Shinoda, Sumio

2014-01-01

378

Essential genes from Arctic bacteria used to construct stable, temperature-sensitive bacterial vaccines.  

PubMed

All bacteria share a set of evolutionarily conserved essential genes that encode products that are required for viability. The great diversity of environments that bacteria inhabit, including environments at extreme temperatures, place adaptive pressure on essential genes. We sought to use this evolutionary diversity of essential genes to engineer bacterial pathogens to be stably temperature-sensitive, and thus useful as live vaccines. We isolated essential genes from bacteria found in the Arctic and substituted them for their counterparts into pathogens of mammals. We found that substitution of nine different essential genes from psychrophilic (cold-loving) bacteria into mammalian pathogenic bacteria resulted in strains that died below their normal-temperature growth limits. Substitution of three different psychrophilic gene orthologs of ligA, which encode NAD-dependent DNA ligase, resulted in bacterial strains that died at 33, 35, and 37 degrees C. One ligA gene was shown to render Francisella tularensis, Salmonella enterica, and Mycobacterium smegmatis temperature-sensitive, demonstrating that this gene functions in both Gram-negative and Gram-positive lineage bacteria. Three temperature-sensitive F. tularensis strains were shown to induce protective immunity after vaccination at a cool body site. About half of the genes that could be tested were unable to mutate to temperature-resistant forms at detectable levels. These results show that psychrophilic essential genes can be used to create a unique class of bacterial temperature-sensitive vaccines for important human pathogens, such as S. enterica and Mycobacterium tuberculosis. PMID:20624965

Duplantis, Barry N; Osusky, Milan; Schmerk, Crystal L; Ross, Darrell R; Bosio, Catharine M; Nano, Francis E

2010-07-27

379

Current Perspectives on Viable but Non-Culturable (VBNC) Pathogenic Bacteria  

PubMed Central

Under stress conditions, many species of bacteria enter into starvation mode of metabolism or a physiologically viable but non-culturable (VBNC) state. Several human pathogenic bacteria have been reported to enter into the VBNC state under these conditions. The pathogenic VBNC bacteria cannot be grown using conventional culture media, although they continue to retain their viability and express their virulence. Though there have been debates on the VBNC concept in the past, several molecular studies have shown that not only can the VBNC state be induced under in vitro conditions but also that resuscitation from this state is possible under appropriate conditions. The most notable advance in resuscitating VBNC bacteria is the discovery of resuscitation-promoting factor (Rpf), which is a bacterial cytokines found in both Gram-positive and Gram-negative organisms. VBNC state is a survival strategy adopted by the bacteria, which has important implication in several fields, including environmental monitoring, food technology, and infectious disease management; and hence it is important to investigate the association of bacterial pathogens under VBNC state and the water/foodborne outbreaks. In this review, we describe various aspects of VBNC bacteria, which include their proteomic and genetic profiles under the VBNC state, conditions of resuscitation, methods of detection, antibiotic resistance, and observations on Rpf. PMID:25133139

Ramamurthy, Thandavarayan; Ghosh, Amit; Pazhani, Gururaja P.; Shinoda, Sumio

2014-01-01

380

Decacationic [70]Fullerene Approach for Efficient Photokilling of Infectious Bacteria and Cancer Cells  

PubMed Central

Photodynamic inactivation of pathogenic bacteria and cancer cells by novel water-soluble decacationic fullerene monoadducts, C60[>M(C3N6+C3)2] and C70[>M(C3N6+C3)2], were investigated. In the presence of a high number of electron-donating iodide anions as parts of quaternary ammonium salts in the arm region, we found that C70[>M(C3N6+C3)2] produced more highly reactive HO• radical than C60[>M(C3N6+C3)2], in addition to singlet oxygen (1O2). This finding offers an explanation of the preferential killing of Gram-positive and Gram-negative bacteria by C60[>M(C3N6+C3)2] and C70[>M(C3N6+C3)2], respectively. The hypothesis is that 1O2 can diffuse more easily into porous cell walls of Gram-positive bacteria to reach sensitive sites, while the less permeable Gram-negative bacterial cell wall needs the more reactive HO• to cause real damage. PMID:24396566

Huang, L.; Wang, M.; Sharma, S. K; Sperandio, F. F.; Maragani, S.; Nayka, S.; Chang, J.

2013-01-01

381

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 supplemented brucella agar for the anaerobes and Mueller-Hinton agar for the corynebacteria. The dapto- mycin MICs determined on Ca2-supplemented (50 mg\\/liter) brucella agar plates were one- to fourfold lower than

Ellie J. C. Goldstein; Diane M. Citron; C. Vreni Merriam; Yumi A. Warren; Kerrin L. Tyrrell; Helen T. Fernandez

2003-01-01

382

A novel compound from the marine bacterium Bacillus pumilus S6-15 inhibits biofilm formation in Gram-positive and Gram-negative species  

Microsoft Academic Search

Biofilm formation is a critical problem in nosocomial infections and in the aquaculture industries and biofilms show high resistance to antibiotics. The aim of the present study was to reveal a novel anti-biofilm compound from marine bacteria against antibiotic resistant Gram-positive and Gram-negative biofilms. The bacterial extract (50 ?g ml) of S6-01 (Bacillus indicus = MTCC 5559) showed 80–90% biofilm inhibition against Escherichia

Chari Nithya; Muthu Gokila Devi; Shunmugiah Karutha Pandian

2011-01-01

383

On-Probe Sample Pretreatment for Direct Analysis of Lipids in Gram-Positive Bacterial Cells by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry  

Microsoft Academic Search

On-probe sample pretreatment using trifluoroacetic acid as an additional reagent enabled the direct detection of phospholipids in whole bacteria by means of matrix-assisted laser desorption ionization mass spectrometry for not only gram-negative organisms but also gram-positive ones with a thicker peptidoglycan layer. Matrix-assisted laser desorption ionization mass spectrome- try (MALDI-MS) has become a powerful method to charac- terize lipid components

Yasuyuki Ishida; Kuniyuki Kitagawa; Akihito Nakayama; Hajime Ohtani

2005-01-01

384

PCR primers and probes for the 16S rRNA gene of most species of pathogenic bacteria, including bacteria found in cerebrospinal fluid.  

PubMed

A set of broad-range PCR primers for the 16S rRNA gene in bacteria were tested, along with three series of oligonucleotide probes to detect the PCR product. The first series of probes is broad in range and consists of a universal bacterial probe, a gram-positive probe, a Bacteroides-Flavobacterium probe, and two probes for other gram-negative species. The second series was designed to detect PCR products from seven major bacterial species or groups frequently causing meningitis: Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae, S. agalactiae, Escherichia coli and other enteric bacteria, Listeria monocytogenes, and Staphylococcus aureus. The third series was designed for the detection of DNA from species or genera commonly considered potential contaminants of clinical samples, including cerebrospinal fluid (CSF): Bacillus, Corynebacterium, Propionibacterium, and coagulase-negative Staphylococcus spp. The primers amplified DNA from all 124 different species of bacteria tested. Southern hybridization testing of the broad-range probes with washes containing 3 M tetramethylammonium chloride indicated that this set of probes correctly identified all but two of the 102 bacterial species tested, the exceptions being Deinococcus radiopugnans and Gardnerella vaginalis. The gram-negative and gram-positive probes hybridized to isolates of two newly characterized bacteria, Alloiococcus otitis and Rochalimaea henselii, as predicted by Gram stain characteristics. The CSF pathogen and contaminant probe sequences were compared with available sequence information and with sequencing data for 32 different species. Testing of the CSF pathogen and contaminant probes against DNA from over 60 different strains indicated that, with the exception of the coagulase-negative Staphylococcus probes, these probes provided the correct identification of bacterial species known to be found in CSF. PMID:7512093

Greisen, K; Loeffelholz, M; Purohit, A; Leong, D

1994-02-01

385

PCR primers and probes for the 16S rRNA gene of most species of pathogenic bacteria, including bacteria found in cerebrospinal fluid.  

PubMed Central

A set of broad-range PCR primers for the 16S rRNA gene in bacteria were tested, along with three series of oligonucleotide probes to detect the PCR product. The first series of probes is broad in range and consists of a universal bacterial probe, a gram-positive probe, a Bacteroides-Flavobacterium probe, and two probes for other gram-negative species. The second series was designed to detect PCR products from seven major bacterial species or groups frequently causing meningitis: Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae, S. agalactiae, Escherichia coli and other enteric bacteria, Listeria monocytogenes, and Staphylococcus aureus. The third series was designed for the detection of DNA from species or genera commonly considered potential contaminants of clinical samples, including cerebrospinal fluid (CSF): Bacillus, Corynebacterium, Propionibacterium, and coagulase-negative Staphylococcus spp. The primers amplified DNA from all 124 different species of bacteria tested. Southern hybridization testing of the broad-range probes with washes containing 3 M tetramethylammonium chloride indicated that this set of probes correctly identified all but two of the 102 bacterial species tested, the exceptions being Deinococcus radiopugnans and Gardnerella vaginalis. The gram-negative and gram-positive probes hybridized to isolates of two newly characterized bacteria, Alloiococcus otitis and Rochalimaea henselii, as predicted by Gram stain characteristics. The CSF pathogen and contaminant probe sequences were compared with available sequence information and with sequencing data for 32 different species. Testing of the CSF pathogen and contaminant probes against DNA from over 60 different strains indicated that, with the exception of the coagulase-negative Staphylococcus probes, these probes provided the correct identification of bacterial species known to be found in CSF. Images PMID:7512093

Greisen, K; Loeffelholz, M; Purohit, A; Leong, D

1994-01-01

386

Study on method of bacteria image recognition  

Microsoft Academic Search

The thesis brings up a method to identify bacteria automatically. It analyzes the features of microscopy image, proposes a method to identify bacteria from microscope image according to these features. At last it proposes a method based on recursion that can rapidly label connected domain.

Hong-wei Shi; Yao-wu Shi; Yong-guang Yin

2011-01-01

387

ENCAPSULATION OF PROBIOTIC BACTERIA IN BIOPOLYMERIC SYSTEM  

Microsoft Academic Search

Encapsulation of probiotic bacteria is generally used to enhance the viability during processing, and also for the target delivery in gastrointestinal tract. Probiotics are used with the fermented dairy products, pharmaceutical products and health supplements. They play a great role for maintaining human health. The survival of these bacteria in the human gastrointestinal system is questionable. In order to protect

Tanzina Huq; Avik Khan; Ruhul A. Khan; Bernard Riedl; Monique Lacroix

2012-01-01

388

Resistance of environmental bacteria to heavy metals  

Microsoft Academic Search

Bacteria were isolated from different naturally polluted environments. Metal-resistant bacteria were selected and minimal inhibitory concentrations of heavy metals (MICs) for each isolate were determined. In addition, the mobility of the most important metallic cations (Cu, Zn, Cr, Cd, Co, Hg) was evaluated by comparing results obtained by two tests of toxicity in solid and liquid media. Results of the

A. Hassen; N. Saidi; M. Cherif; A. Boudabous

1998-01-01

389

Modulating immune responses with probiotic bacteria  

Microsoft Academic Search

For many years, probiotic bacteria have been known to confer health benefits to the consumer. One possible mechanism for this may be the ability of probiotic bacteria to modulate immune responses. Oral administration of Lactobacillus casei strain Shirota (LcS) has been found to enhance innate immunity by stimulating the activity of splenic NK cells. Oral feeding with killed LcS was

Takeshi Matsuzaki; James Chin

2000-01-01

390

Symbiosis of methanogenic bacteria and sapropelic protozoa  

Microsoft Academic Search

Fluorescent bacteria were demonstrated to be abundantly spread as single cells throughout the cytoplasm of the giant amoeba Pelomyxa palustris, the sapropelic ciliate Metopus striatus and six other anaerobic protozoa examined. The endosymbionts of P. palustris and M. striatus were identified as methanogenic bacteria on the basis of the presence of the deazaflavin coenzyme F420 and the pterin compound F342.

Johan J. A. van Bruggen; Claudius K. Stumm; Godfried D. Vogels

1983-01-01

391

Do symbiotic bacteria subvert host immunity?  

Microsoft Academic Search

The mammalian intestine is home to dense and complex indigenous bacterial communities. Most of these bacteria establish beneficial symbiotic relationships with their hosts, making important contributions to host metabolism and digestive efficiency. The vast numbers of intestinal bacteria and their proximity to host tissues raise the question of how symbiotic host–bacterial relationships are established without eliciting potentially harmful immune responses.

Lora V. Hooper

2009-01-01

392

Bacteria size determination by elastic light scattering  

Microsoft Academic Search

Light extinction and angular scattering measurements were performed on three species of bacteria with different sizes and shapes ( Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis). The Gaussian ray approximation of anomalous diffraction theory was used to determine the average bacteria size from transmission measurements. A rescaled spectra combining multiple angular data was analyzed in the framework of the Rayleigh-Gans

A. Katz; Alexandra Alimova; Min Xu; E. Rudolph; M. K. Shah; H. E. Savage; R. B. Rosen; S. A. McCormick; R. R. Alfano

2003-01-01

393

Energy transduction in lactic acid bacteria  

Microsoft Academic Search

In the discovery of some general principles of energy transduction, lactic acid bacteria have played an important role. In this review, the energy transducing processes of lactic acid bacteria are discussed with the emphasis on the major developments of the past 5 years. This work not only includes the biochemistry of the enzymes and the bioenergetics of the processes, but

Bert Poolman

1993-01-01

394

Proteolytic systems in lactic acid bacteria  

Microsoft Academic Search

The proteolytic systems of lactic acid bacteria are important as a means of making protein and peptide N available for growth and as part of the curing or maturation processes which give foods their characteristic rheological and organoleptic properties. The proteolytic systems of lactic acid bacteria are described in relation to their growth and their functions in protein-rich foods. Their

Barry A. Law; Jens Kolstad; Pekka Varmanen; Bert Poolman I; Wil N. Konings

1983-01-01

395

Study of Lactobacillus as Probiotic Bacteria  

Microsoft Academic Search

Because of inhibitory effect, selected probiotic lactobacilli may be used as biological preservative, so, the aim of this study was to present some data on lactobacillus as probiotic bacteria. Lactic acid bacteria were isolated from sausage. Each isolate of lactobacillus species was identified by biochemical tests and comparing their sugar fermentation pattern. Antibacterial activities were done by an agar spot,

J Nowroozi; M Mirzaii; M Norouzi

396

Bile salt biotransformations by human intestinal bacteria  

Microsoft Academic Search

Secondary bile acids, produced solely by intesti- nal bacteria, can accumulate to high levels in the enter- ohepatic circulation of some individuals and may contribute to the pathogenesis of colon cancer, gallstones, and other gastrointestinal (GI) diseases. Bile salt hydrolysis and hy- droxy group dehydrogenation reactions are carried out by a broad spectrum of intestinal anaerobic bacteria, whereas bile acid

Jason M. Ridlon; Dae-Joong Kang; Phillip B. Hylemon

2005-01-01

397

Method of dispersing a hydrocarbon using bacteria  

DOEpatents

A new protozoan derived microbial consortia and method for their isolation are provided. The isolated consortia and bacteria are useful for treating wastes such as trichloroethylene and trinitrotoluene. The isolated consortia, bacteria, and dispersants are useful for dispersing hydrocarbons such as oil, creosote, wax, and grease.

Tyndall, R.L.

1996-09-24

398

Possible determinants of rhizosphere competence of bacteria  

Microsoft Academic Search

Because extensive colonization of the rhizosphere is important to obtain the benefits of bacterial inoculation, a study was conducted to determine possible traits that are important for rhizosphere competence of bacteria. The final population sizes of 19 bacteria introduced into the rhizosphere of soybeans grown in nonsterile soil differed markedly. The ability to colonize the rhizosphere was not correlated with

P. K Jjemba; Martin Alexander

1999-01-01

399

Influence of surfaces on sulphidogenic bacteria  

Microsoft Academic Search

Sulphidogenic bacteria in oil reservoirs are of great economic importance in terms of souring, fouling and corrosion. Mixed cultures containing these bacteria were isolated from chalk formations in North Sea oil reservoirs. These were thermophilic cultures, growing optimally at 60°C. Oil formations are porous matrices, providing a very large surface area and ideal conditions for bacterial attachment, survival and growth.

Catherine J Bass; Jeremy S Webb; Peter F Sanders

1996-01-01

400

Bioengineered Nisin A Derivatives with Enhanced Activity against Both Gram Positive and Gram Negative Pathogens  

PubMed Central

Nisin is a bacteriocin widely utilized in more than 50 countries as a safe and natural antibacterial food preservative. It is the most extensively studied bacteriocin, having undergone decades of bioengineering with a view to improving function and physicochemical properties. The discovery of novel nisin variants with enhanced activity against clinical and foodborne pathogens has recently been described. We screened a randomized bank of nisin A producers and identified a variant with a serine to glycine change at position 29 (S29G), with enhanced efficacy against S. aureus SA113. Using a site-saturation mutagenesis approach we generated three more derivatives (S29A, S29D and S29E) with enhanced activity against a range of Gram positive drug resistant clinical, veterinary and food pathogens. In addition, a number of the nisin S29 derivatives displayed superior antimicrobial activity to nisin A when assessed against a range of Gram negative food-associated pathogens, including E. coli, Salmonella enterica serovar Typhimurium and Cronobacter sakazakii. This is the first report of derivatives of nisin, or indeed any lantibiotic, with enhanced antimicrobial activity against both Gram positive and Gram negative bacteria. PMID:23056510

Field, Des; Begley, Maire; O'Connor, Paula M.; Daly, Karen M.; Hugenholtz, Floor; Cotter, Paul D.; Hill, Colin; Ross, R. Paul

2012-01-01

401

Development of a Flow Chart for Identification of Gram-Positive Anaerobic Cocci in the Clinical Laboratory?  

PubMed Central

Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms that are isolated from clinical specimens more often than any group of anaerobic bacteria except Bacteroides species, yet many strains are still difficult or impossible to identify in the diagnostic laboratory. In this study, a total of 124 strains, including 13 reference strains of GPAC species and 111 isolates that had been recovered from clinical specimens previously and identified by 16S rRNA gene sequencing, were subjected to biochemical characterization. Based on the results, a short biochemical scheme that involves the minimum essential biochemical tests for accurate identification of clinically important GPAC was developed. PMID:17135439

Song, Yuli; Liu, Chengxu; Finegold, Sydney M.

2007-01-01

402

HYDROCARBON-DEGRADING BACTERIA AND SURFACTANT ACTIVITY  

SciTech Connect

Fate of benzene ethylbenzene toluene xylenes (BTEX) compounds through biodegradation was investigated using two different bacteria, Ralstonia picketti (BP-20) and Alcaligenes piechaudii (CZOR L-1B). These bacteria were isolated from extremely polluted petroleum hydrocarbon contaminated soils. PCR and Fatty Acid Methyl Ester (FAME) were used to identify the isolates. Biodegradation was measured using each organism individually and in combination. Both bacteria were shown to degrade each of the BTEX compounds. Alcaligenes piechaudii biodegraded BTEXs more efficiently while mixed with BP-20 and individually. Biosurfactant production was observed by culture techniques. In addition 3-hydroxy fatty acids, important in biosurfactant production, was observed by FAME analysis. In the all experiments toluene and m+p- xylenes were better growth substrates for both bacteria than the other BTEX compounds. In addition, the test results indicate that the bacteria could contribute to bioremediation of aromatic hydrocarbons (BTEX) pollution increase biodegradation through the action by biosurfactants.

Brigmon, R; Topher Berry, T; Grazyna A. Plaza, G; jacek Wypych, j

2006-08-15

403

Chemotactic selection of pollutant degrading soil bacteria  

DOEpatents

A method is described for identifying soil microbial strains which may be bacterial degraders of pollutants. This method includes: Placing a concentration of a pollutant in a substantially closed container; placing the container in a sample of soil for a period of time ranging from one minute to several hours; retrieving the container and collecting its contents; microscopically determining the identity of the bacteria present. Different concentrations of the pollutant can be used to determine which bacteria respond to each concentration. The method can be used for characterizing a polluted site or for looking for naturally occurring biological degraders of the pollutant. Then bacteria identified as degraders of the pollutant and as chemotactically attracted to the pollutant are used to innoculate contaminated soil. To enhance the effect of the bacteria on the pollutant, nutrients are cyclicly provided to the bacteria then withheld to alternately build up the size of the bacterial colony or community and then allow it to degrade the pollutant.

Hazen, T.C.

1991-03-04

404

Aspects of eukaryotic-like signaling in Gram-positive cocci: a focus on virulence  

PubMed Central

Living organisms adapt to the dynamic external environment for their survival. Environmental adaptation in prokaryotes is thought to be primarily accomplished by signaling events mediated by two-component systems, consisting of histidine kinases and response regulators. However, eukaryotic-like serine/threonine kinases (STKs) have recently been described to regulate growth, antibiotic resistance and virulence of pathogenic bacteria. This article summarizes the role of STKs and their cognate phosphatases (STPs) in Gram-positive cocci that cause invasive infections in humans. Given that a large number of inhibitors to eukaryotic STKs are approved for use in humans, understanding how serine/threonine phosphorylation regulates virulence and antibiotic resistance will be beneficial for the development of novel therapeutic strategies against bacterial infections. PMID:21797690

Burnside, Kellie; Rajagopal, Lakshmi

2011-01-01

405

Functional Gold Nanoparticles as Potent Antimicrobial Agents against Multi-Drug-Resistant Bacteria.  

PubMed

We present the use of functionalized gold nanoparticles (AuNPs) to combat multi-drug-resistant pathogenic bacteria. Tuning of the functional groups on the nanoparticle surface provided gold nanoparticles that were effective against both Gram-negative and Gram-positive uropathogens, including multi-drug-resistant pathogens. These AuNPs exhibited low toxicity to mammalian cells, and bacterial resistance was not observed after 20 generations. A strong structure-activity relationship was observed as a function of AuNP functionality, providing guidance to activity prediction and rational design of effective antimicrobial nanoparticles. PMID:25232643

Li, Xiaoning; Robinson, Sandra M; Gupta, Akash; Saha, Krishnendu; Jiang, Ziwen; Moyano, Daniel F; Sahar, Ali; Riley, Margaret A; Rotello, Vincent M

2014-10-28

406

In Vitro Activity of Ceftaroline against 623 Diverse Strains of Anaerobic Bacteria ?  

PubMed Central

The in vitro activities of ceftaroline, a novel, parenteral, broad-spectrum cephalosporin, and four comparator antimicrobials were determined against anaerobic bacteria. Against Gram-positive strains, the activity of ceftaroline was similar to that of amoxicillin-clavulanate and four to eight times greater than that of ceftriaxone. Against Gram-negative organisms, ceftaroline showed good activity against ?-lactamase-negative strains but not against the members of the Bacteroides fragilis group. Ceftaroline showed potent activity against a broad spectrum of anaerobes encountered in respiratory, skin, and soft tissue infections. PMID:20100877

Citron, D. M.; Tyrrell, K. L.; Merriam, C. V.; Goldstein, E. J. C.

2010-01-01

407

In vitro activity of an evernimicin derivative, SCH27899, against anaerobic bacteria and Propionibacterium acnes.  

PubMed

The in vitro activity of SCH27899, a novel oligosaccharide antimicrobial agent, was compared with those of representatives of six classes of antimicrobial agents (piperacillin, clarithromycin, clindamycin, vancomycin, sitafloxacin and metronidazole) against clinical isolates of anaerobic bacteria and Propionibacterium acnes. Against Peptostreptococcus: spp. and Clostridium difficile, SCH27899 was the most potent (MIC(90) < 0.125 mg/L) of the agents examined. Besides these Gram-positive anaerobes, SCH27899 showed a moderate level of activity against Prevotella bivia, Prevotella intermedia and Porphyromonas: spp. (MIC(90)< or = 4 mg/L). PMID:10980176

Tanaka, K; Kato, N; Watanabe, K

2000-09-01

408

Potential role of bacteria packaging by protozoa in the persistence and transmission of pathogenic bacteria.  

PubMed

Many pathogenic bacteria live in close association with protozoa. These unicellular eukaryotic microorganisms are ubiquitous in various environments. A number of protozoa such as amoebae and ciliates ingest pathogenic bacteria, package them usually in membrane structures, and then release them into the environment. Packaged bacteria are more resistant to various stresses and are more apt to survive than free bacteria. New evidence indicates that protozoa and not bacteria control the packaging process. It is possible that packaging is more common than suspected and may play a major role in the persistence and transmission of pathogenic bacteria. To confirm the role of packaging in the propagation of infections, it is vital that the molecular mechanisms governing the packaging of bacteria by protozoa be identified as well as elements related to the ecology of this process in order to determine whether packaging acts as a Trojan Horse. PMID:24904553

Denoncourt, Alix M; Paquet, Valérie E; Charette, Steve J

2014-01-01

409

Are uncultivated bacteria really uncultivable?  

PubMed

Many strategies have been used to increase the number of bacterial cells that can be grown from environmental samples but cultivation efficiency remains a challenge for microbial ecologists. The difficulty of cultivating a fraction of bacteria in environmental samples can be classified into two non-exclusive categories. Bacterial taxa with no cultivated representatives for which appropriate laboratory conditions necessary for growth are yet to be identified. The other class is cells in a non-dividing state (also known as dormant or viable but not culturable cells) that require the removal or addition of certain factors to re-initiate growth. A number of strategies, from simple to high throughput techniques, are reviewed that have been used to increase the cultivation efficiency of environmental samples. Some of the underlying mechanisms that contribute to the success of these cultivation strategies are described. Overall this review emphasizes the need of researchers to first understand the factors that are hindering cultivation to identify the best strategies to improve cultivation efficiency. PMID:23059723

Puspita, Indun Dewi; Kamagata, Yoichi; Tanaka, Michiko; Asano, Kozo; Nakatsu, Cindy H

2012-01-01

410

Comparative cytotoxicity of periodontal bacteria  

SciTech Connect

The direct cytotoxicity of sonic extracts (SE) from nine periodontal bacteria for human gingival fibroblasts (HGF) was compared. Equivalent dosages (in terms of protein concentration) of SE were used to challenge HGF cultures. The cytotoxic potential of each SE was assessed by its ability to (1) inhibit HGF proliferation, as measured by direct cell counts; (2) inhibit 3H-thymidine incorporation in HGF cultures; or (3) cause morphological alterations of the cells in challenged cultures. The highest concentration (500 micrograms SE protein/ml) of any of the SEs used to challenge the cells was found to be markedly inhibitory to the HGFs by all three of the criteria of cytotoxicity. At the lowest dosage tested (50 micrograms SE protein/ml); only SE from Actinobacillus actinomycetemcomitans, Bacteroides gingivalis, and Fusobacterium nucleatum caused a significant effect (greater than 90% inhibition or overt morphological abnormalities) in the HGFs as determined by any of the criteria employed. SE from Capnocytophaga sputigena, Eikenella corrodens, or Wolinella recta also inhibited cell proliferation and thymidine incorporation at this dosage; however, the degree of inhibition (5-50%) was consistently, clearly less than that of the first group of three organisms named above. The SE of the three other organisms tested (Actinomyces odontolyticus, Bacteroides intermedius, and Streptococcus sanguis) had little or no effect (0-10% inhibition) at this concentration. The data suggest that the outcome of the interaction between bacterial components and normal resident cells of the periodontium is, at least in part, a function of the bacterial species.

Stevens, R.H.; Hammond, B.F.

1988-11-01

411

Tape Cassette Bacteria Detection System  

NASA Technical Reports Server (NTRS)

The design, fabrication, and testing of an automatic bacteria detection system with a zero-g capability and based on the filter-capsule approach is described. This system is intended for monitoring the sterility of regenerated water in a spacecraft. The principle of detection is based on measuring the increase in chemiluminescence produced by the action of bacterial porphyrins (i.e., catalase, cytochromes, etc.) on a luminol-hydrogen peroxide mixture. Since viable as well as nonviable organisms initiate this luminescence, viable organisms are detected by comparing the signal of an incubated water sample with an unincubated control. Higher signals for the former indicate the presence of viable organisms. System features include disposable sealed sterile capsules, each containing a filter membrane, for processing discrete water samples and a tape transport for moving these capsules through a processing sequence which involves sample concentration, nutrient addition, incubation, a 4 Molar Urea wash and reaction with luminol-hydrogen peroxide in front of a photomultiplier tube. Liquids are introduced by means of a syringe needle which pierces a rubber septum contained in the wall of the capsule. Detection thresholds obtained with this unit towards E. coli and S. marcescens assuming a 400 ml water sample are indicated.

1973-01-01

412

Seeing green bacteria in a new light: genomics-enabled studies of the photosynthetic apparatus in green sulfur bacteria and filamentous anoxygenic phototrophic bacteria  

Microsoft Academic Search

Based upon their photosynthetic nature and the presence of a unique light-harvesting antenna structure, the chlorosome, the photosynthetic green bacteria are defined as a distinctive group in the Bacteria. However, members of the two taxa that comprise this group, the green sulfur bacteria (Chlorobi) and the filamentous anoxygenic phototrophic bacteria (“Chloroflexales”), are otherwise quite different, both physiologically and phylogenetically. This

Niels-Ulrik Frigaard; Donald A. Bryant

2004-01-01

413

Engineering commensal bacteria for prophylaxis against infection  

PubMed Central

Infectious diseases are the leading causes of death worldwide. The development of efficient and low cost prophylactics to prevent pathogenic infection is given high priority in the twenty-first century. Commensal bacteria are largely seen as harmless and can survive symbiotically (in many cases) in niches throughout the human body. Advances in genetic engineering and understanding of pathogenesis have revealed many potential strategies to develop engineered bacteria for prophylaxis purposes: including live vaccines and anti-infective agents. In this review we discuss recent advances and potentialities of prophylaxis with engineered bacteria. PMID:22459613

Goh, Yih-Lin; He, HongFei; March, John C.

2012-01-01

414

Do symbiotic bacteria subvert host immunity?  

PubMed

The mammalian intestine is home to dense and complex indigenous bacterial communities. Most of these bacteria establish beneficial symbiotic relationships with their hosts, making important contributions to host metabolism and digestive efficiency. The vast numbers of intestinal bacteria and their proximity to host tissues raise the question of how symbiotic host-bacterial relationships are established without eliciting potentially harmful immune responses. In light of the varied ways in which pathogenic bacteria manipulate host immunity, this Opinion article explores the role of immune suppression, subversion and evasion in the establishment of symbiotic host-bacterial associations. PMID:19369952

Hooper, Lora V

2009-05-01

415

Electromechanical and elastic probing of bacteria in a cell culture medium.  

PubMed

Rapid phenotype characterization and identification of cultured cells, which is needed for progress in tissue engineering and drug testing, requires an experimental technique that measures physical properties of cells with sub-micron resolution. Recently, band excitation piezoresponse force microscopy (BEPFM) has been proven useful for recognition and imaging of bacteria of different types in pure water. Here, the BEPFM method is performed for the first time on physiologically relevant electrolyte media, such as Dulbecco's phosphate-buffered saline (DPBS) and Dulbecco's modified Eagle's medium (DMEM). Distinct electromechanical responses for Micrococcus lysodeikticus (Gram-positive) and Pseudomonas fluorescens (Gram-negative) bacteria in DPBS are demonstrated. The results suggest that mechanical properties of the outer surface coating each bacterium, as well as the electrical double layer around them, are responsible for the BEPFM image formation mechanism in electrolyte media. PMID:22641388

Thompson, G L; Reukov, V V; Nikiforov, M P; Jesse, S; Kalinin, S V; Vertegel, A A

2012-06-22

416

Multi-wavelength resonance Raman spectroscopy of bacteria to study the effects of growth condition  

NASA Astrophysics Data System (ADS)

We will examine the use of multi-wavelength UV resonance-Raman signatures to identify the effects of growth phase on different types of bacteria. Gram positive and gram-negative species, Escherichia coli, Bacillus cereus, Citrobacter koseri and Citrobacter braakii were grown to logarithmic and stationary phases in different culture media. Raman spectra of bacteria were obtained by sequential illumination of samples between 220 and 260 nm; a range which encompasses the resonance frequencies of cellular components. In addition to the information contained in the single spectrum, this two-dimensional signature contains information reflecting variations in resonance cross sections with illumination wavelength. Results of our algorithms in identifying the differences between these germs are discussed. Preliminary results indicate that growth affects the Raman signature, but not to an extent that would negate identification of the species.

Kunapareddy, Nagapratima; Grun, Jacob; Lunsford, Robert; Gillis, David; Nikitin, Sergei; Wang, Zheng

2012-06-01

417

Porphyrin Metabolisms in Human Skin Commensal Propionibacterium acnes Bacteria: Potential Application to Monitor Human Radiation Risk  

PubMed Central

Propionibacterium acnes (P. acnes), a Gram-positive anaerobic bacterium, is a commensal organism in human skin. Like human cells, the bacteria produce porphyrins, which exhibit fluorescence properties and make bacteria visible with a Wood’s lamp. In this review, we compare the porphyrin biosynthesis in humans and P. acnes. Also, since P. acnes living on the surface of skin receive the same radiation exposure as humans, we envision that the changes in porphyrin profiles (the absorption spectra and/or metabolism) of P. acnes by radiation may mirror the response of human cells to radiation. The porphyrin profiles of P. acnes may be a more accurate reflection of radiation risk to the patient than other biodosimeters/biomarkers such as gene up-/down-regulation, which may be non-specific due to patient related factors such as autoimmune diseases. Lastly, we discuss the challenges and possible solutions for using the P. acnes response to predict the radiation risk. PMID:23231351

Shu, M.; Kuo, S.; Wang, Y.; Jiang, Y.; Liu, Y.-T.; Gallo, R.L.; Huang, C.-M.

2013-01-01

418

Electromechanical and elastic probing of bacteria in a cell culture medium  

NASA Astrophysics Data System (ADS)

Rapid phenotype characterization and identification of cultured cells, which is needed for progress in tissue engineering and drug testing, requires an experimental technique that measures physical properties of cells with sub-micron resolution. Recently, band excitation piezoresponse force microscopy (BEPFM) has been proven useful for recognition and imaging of bacteria of different types in pure water. Here, the BEPFM method is performed for the first time on physiologically relevant electrolyte media, such as Dulbecco’s phosphate-buffered saline (DPBS) and Dulbecco’s modified Eagle’s medium (DMEM). Distinct electromechanical responses for Micrococcus lysodeikticus (Gram-positive) and Pseudomonas fluorescens (Gram-negative) bacteria in DPBS are demonstrated. The results suggest that mechanical properties of the outer surface coating each bacterium, as well as the electrical double layer around them, are responsible for the BEPFM image formation mechanism in electrolyte media.

Thompson, G. L.; Reukov, V. V.; Nikiforov, M. P.; Jesse, S.; Kalinin, S. V.; Vertegel, A. A.

2012-06-01

419

Rapid estimation of bacteria by a fluorescent gold nanoparticle-polythiophene composite.  

PubMed

Herein we present a facile method for rapid quantitation of bacterial cells over several logarithmic dilutions. The quantitation is based on loss of the fluorescence intensity of a positively charged Au nanoparticle-polythiophene composite in the presence of bacterial cells. The present method allowed estimation of both Gram-positive and Gram-negative bacteria with cells as low as 1000. Transmission electron microscopic investigations revealed attachment of the composite with bacteria with no discernible change in the morphology of the cells. Further, dynamic light scattering experiments indicated preferential attachment of smaller composite particles over larger ones, which were also attached at higher bacterial concentrations. The ease of operation with minimal sample manipulation steps, high sensitivity, quantitative detection, and its generality offer specific advantages over conventional methods. PMID:18816019

Panda, Biswa Ranjan; Singh, Atul Kumar; Ramesh, Aiyagari; Chattopadhyay, Arun

2008-10-21

420

Lipid Metabolism of Rumen Ciliates and Bacteria  

PubMed Central

The total lipid and free fatty acid contents of Isotricha intestinalis, Entodinium simplex, and the rumen bacterial flora of the respective protozoa were determined. Warburg manometric data showed that the sodium salts of tributyrin, oleic, and acetic acids stimulated gas production in I. intestinalis, whereas tributyrin was stimulatory with E. simplex and less active with oleic and acetic acids. Rumen bacteria provided fatty acids produced lower manometric gaseous increases when compared with the protozoa. Volatile fatty acids were produced by I. intestinalis and rumen bacteria with tributyrin, but not with tripalmitin. Sodium oleate gave little volatile fatty acid response with I. intestinalis or rumen bacteria. Washed suspensions of I. intestinalis and rumen bacteria concentrated C14-labeled oleic, palmitic, stearic, and linoleic acids within the cells during short incubation periods. Autoradiographs demonstrated the conversion of C14-labeled oleic, palmitic, stearic, linoleic, and acetic acids in the rumen protozoa and bacterial cells. PMID:14000915

Williams, P. P.; Gutierrez, J.; Davis, R. E.

1963-01-01

421

Methods for dispersing hydrocarbons using autoclaved bacteria  

DOEpatents

A method of dispersing a hydrocarbon includes the following steps: providing a bacterium selected from the following group: ATCC 85527, ATCC 75529, and ATCC 55638, a mutant of any one of these bacteria possessing all the identifying characteristics of any one of these bacteria, and mixtures; autoclaving the bacterium to derive a dispersant solution; and contacting the dispersant solution with a hydrocarbon to disperse the hydrocarbon. Moreover, a method for preparing a dispersant solution includes the following steps: providing a bacterium selected from the following group: ATCC 75527, ATCC 75529, and ATCC 55638, a mutant of any one of these bacteria possessing all the identifying characteristics of any one of these bacteria, and mixtures; and autoclaving the bacterium to derive a dispersant solution.

Tyndall, R.L.

1996-11-26

422

[Regulation of chitinase genes expression in bacteria].  

PubMed

Chitinases, which can hydrolyze chitin, occur in a wide range of microorganisms including viruses, bacteria, and fungi. The derivatives of chitin are potentially useful in several areas such as food processing, medicines, and biological control in agriculture. Some bacteria can uptake and utilize chitin as carbon source by secreting chitinase. The chitin is degraded into chito-oligosaccharides [(GlcNAc)n] or N-acetylglucosamine (GlcNAc) by chitinases, and then the chitin derivatives are transferred into cells by specific transport systems of bacteria. The intracellular chitin derivatives activate or suppress the transcription of a series of chi genes and affect the amount of chitinase. The expression of chitinase genes are strictly regulated by various regulatory factors and responsive cis-acting elements. The present review will focus on the transport system and the regulation of chitinase genes expression in bacteria. PMID:21993277

Xie, Chi-Chu; Jia, Hai-Yun; Chen, Yue-Hua

2011-10-01

423

Probiotic Bacteria Induce a ‘Glow of Health’  

E-print Network

Radiant skin and hair are universally recognized as indications of good health. However, this ‘glow of health’ display remains poorly understood. We found that feeding of probiotic bacteria to aged mice induced integumentary ...

Levkovich, Tatiana

424

Reverse and flick: Hybrid locomotion in bacteria  

E-print Network

Many bacteria are motile. They use one or more helical flagella as propellers, rotating them like the corkscrew on a wine bottle opener. Despite the limited morphological repertoire of the propulsive system, radically ...

Stocker, Roman

425

Impacts of Antibiotic-Resistant Bacteria.  

National Technical Information Service (NTIS)

Partial Contents: Summary, Conclusions, Issues and Options; Introduction; Antibiotic Use and Resistance in the Community (Populations Susceptible to Antibiotic-Resistant Bacteria, Factors in the Emergence of Bacterial Diseases, Changes in Disease Patterns...

1995-01-01

426

Comparative genomics of the lactic acid bacteria  

PubMed Central

Lactic acid-producing bacteria are associated with various plant and animal niches and play a key role in the production of fermented foods and beverages. We report nine genome sequences representing the phylogenetic and functional diversity of these bacteria. The small genomes of lactic acid bacteria encode a broad repertoire of transporters for efficient carbon and nitrogen acquisition from the nutritionally rich environments they inhabit and reflect a limited range of biosynthetic capabilities that indicate both prototrophic and auxotrophic strains. Phylogenetic analyses, comparison of gene content across the group, and reconstruction of ancestral gene sets indicate a combination of extensive gene loss and key gene acquisitions via horizontal gene transfer during the coevolution of lactic acid bacteria with their habitats. PMID:17030793

Makarova, K.; Slesarev, A.; Wolf, Y.; Sorokin, A.; Mirkin, B.; Koonin, E.; Pavlov, A.; Pavlova, N.; Karamychev, V.; Polouchine, N.; Shakhova, V.; Grigoriev, I.; Lou, Y.; Rohksar, D.; Lucas, S.; Huang, K.; Goodstein, D. M.; Hawkins, T.; Plengvidhya, V.; Welker, D.; Hughes, J.; Goh, Y.; Benson, A.; Baldwin, K.; Lee, J.-H.; Diaz-Muniz, I.; Dosti, B.; Smeianov, V.; Wechter, W.; Barabote, R.; Lorca, G.; Altermann, E.; Barrangou, R.; Ganesan, B.; Xie, Y.; Rawsthorne, H.; Tamir, D.; Parker, C.; Breidt, F.; Broadbent, J.; Hutkins, R.; O'Sullivan, D.; Steele, J.; Unlu, G.; Saier, M.; Klaenhammer, T.; Richardson, P.; Kozyavkin, S.; Weimer, B.; Mills, D.

2006-01-01

427

Acidophilic, heterotrophic bacteria of acidic mine waters  

SciTech Connect

Obligately acidophilic, heterotrophic bacteria were isolated both from enrichment cultures developed with acidic mine water and from natural mine drainage. The bacteria were grouped by the ability to utilize a number of organic acids as sole carbon sources. None of the strains were capable of chemolithotrophic growth on inorganic reduced iron and sulfur compounds. All bacteria were rod shaped, gram negative, nonencapsulated, motile, capable of growth at pH 2.6 but not at pH 6.0, catalase and oxidase positive, strictly aerobic, and capable of growth on citric acid. The bacteria were cultivatable on solid nutrient media only if agarose was