These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Transformation of gram positive bacteria by sonoporation  

DOEpatents

The present invention provides a sonoporation-based method that can be universally applied for delivery of compounds into Gram positive bacteria. Gram positive bacteria which can be transformed by sonoporation include, for example, Bacillus, Streptococcus, Acetobacterium, and Clostridium. Compounds which can be delivered into Gram positive bacteria via sonoporation include nucleic acids (DNA or RNA), proteins, lipids, carbohydrates, viruses, small organic and inorganic molecules, and nano-particles.

Yang, Yunfeng; Li, Yongchao

2014-03-11

2

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

3

Bacteriocins of gram-positive bacteria.  

PubMed Central

In recent years, a group of antibacterial proteins produced by gram-positive bacteria have attracted great interest in their potential use as food preservatives and as antibacterial agents to combat certain infections due to gram-positive pathogenic bacteria. They are ribosomally synthesized peptides of 30 to less than 60 amino acids, with a narrow to wide antibacterial spectrum against gram-positive bacteria; the antibacterial property is heat stable, and a producer strain displays a degree of specific self-protection against its own antibacterial peptide. In many respects, these proteins are quite different from the colicins and other bacteriocins produced by gram-negative bacteria, yet customarily they also are grouped as bacteriocins. Although a large number of these bacteriocins (or bacteriocin-like inhibitory substances) have been reported, only a few have been studied in detail for their mode of action, amino acid sequence, genetic characteristics, and biosynthesis mechanisms. Nevertheless, in general, they appear to be translated as inactive prepeptides containing an N-terminal leader sequence and a C-terminal propeptide component. During posttranslational modifications, the leader peptide is removed. In addition, depending on the particular type, some amino acids in the propeptide components may undergo either dehydration and thioether ring formation to produce lanthionine and beta-methyl lanthionine (as in lantibiotics) or thio ester ring formation to form cystine (as in thiolbiotics). Some of these steps, as well as the translocation of the molecules through the cytoplasmic membrane and producer self-protection against the homologous bacteriocin, are mediated through specific proteins (enzymes). Limited genetic studies have shown that the structural gene for such a bacteriocin and the genes encoding proteins associated with immunity, translocation, and processing are present in a cluster in either a plasmid, the chromosome, or a transposon. Following posttranslational modification and depending on the pH, the molecules may either be released into the environment or remain bound to the cell wall. The antibacterial action against a sensitive cell of a gram-positive strain is produced principally by destabilization of membrane functions. Under certain conditions, gram-negative bacterial cells can also be sensitive to some of these molecules. By application of site-specific mutagenesis, bacteriocin variants which may differ in their antimicrobial spectrum and physicochemical characteristics can be produced. Research activity in this field has grown remarkably but sometimes with an undisciplined regard for conformity in the definition, naming, and categorization of these molecules and their genetic effectors. Some suggestions for improved standardization of nomenclature are offered. PMID:7603408

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

1995-01-01

4

Lipoprotein biogenesis in Gram-positive bacteria: knowing when to  

E-print Network

Lipoprotein biogenesis in Gram- positive bacteria: knowing when to hold `em, knowing when to fold Tyne, NE1 8ST, UK Gram-positive bacterial lipoproteins are a functionally diverse and important class of these proteins, their role in virulence in Gram-positive bacteria and their potential as vaccine candidates

Palmer, Tracy

5

Classification of Bacteriocins from Gram-Positive Bacteria  

NASA Astrophysics Data System (ADS)

Bacteriocins are ribosomally synthesised antimicrobial peptides produced by bacteria, including many Gram-positive species. The classification of bacteriocins from Gram-positive bacteria is complicated by their heterogeneity and thus, as the number of Gram-positive bacteriocins identified has continued to increase, classification schemes have had to continuously evolve. Here, we review the various classification approaches, both historical and current, their underlying scientific basis and their relative merit, and suggest a rational scheme given the state of the art.

Rea, Mary C.; Ross, R. Paul; Cotter, Paul D.; Hill, Colin

6

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

7

Methods for targetted mutagenesis in gram-positive bacteria  

SciTech Connect

The present invention provides a method of targeted mutagenesis in Gram-positive bacteria. In particular, the present invention provides a method that effectively integrates a suicide integrative vector into a target gene in the chromosome of a Gram-positive bacterium, resulting in inactivation of the target gene.

Yang, Yunfeng

2014-05-27

8

Biosynthesis of Peptide Signals in Gram-Positive Bacteria  

Microsoft Academic Search

Gram-positive bacteria coordinate social behavior by sensing the extracellular level of peptide signals. These signals are biosynthesized through divergent pathways and some possess unusual functional chemistry as a result of posttranslational modifications. In this chapter, the biosynthetic pathways of Bacillus intracellular signaling peptides, Enterococcus pheromones, Bacillus subtilis competence pheromones, and cyclic peptide signals from Staphylococcus and other bacteria are covered.

Matthew Thoendel; Alexander R. Horswill

2010-01-01

9

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. PMID:25419466

McBride, Shonna M.

2014-01-01

10

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

11

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

12

Regulation of Apoptosis by Gram-Positive Bacteria  

PubMed Central

Apoptosis, or programmed cell death (PCD), is an important physiological mechanism, through which the human immune system regulates homeostasis and responds to diverse forms of cellular damage. PCD may also be involved in immune counteraction to microbial infection. Over the past decade, the amount of research on bacteria-induced PCD has grown tremendously, and the implications of this mechanism on immunity are being elucidated. Some pathogenic bacteria actively trigger the suicide response in critical lineages of leukocytes that orchestrate both the innate and adaptive immune responses; other bacteria proactively prevent PCD to benefit their own survival and persistence. Currently, the microbial virulence factors, which represent the keys to unlocking the suicide response in host cells, are a primary focus of this field. In this review, we discuss these bacterial “apoptosis regulatory molecules” and the apoptotic events they either trigger or prevent, the host target cells of this regulatory activity, and the possible ramifications for immunity to infection. Gram-positive pathogens including Staphylococcus, Streptococcus, Bacillus, Listeria, and Clostridia species are discussed as important agents of human infection that modulate PCD pathways in eukaryotic cells. PMID:19081777

Ulett, Glen C.; Adderson, Elisabeth E.

2008-01-01

13

Photodynamic inactivation of Gram-positive bacteria employing natural resources.  

PubMed

The aim of this paper was to investigate a collection of plant extracts from Argentina as a source of new natural photosensitizers (PS) to be used in Photodynamic Inactivation (PDI) of bacteria. A collection of plants were screened for phototoxicity upon the Gram-positive species Staphylococcus epidermidis. Three extracts turned out to be photoactive: Solanum verbascifolium flower, Tecoma stans flower and Cissus verticillata root. Upon exposure to a light dose of 55J/cm(2), they induced 4, 2 and 3logs decrease in bacterial survival, respectively. Photochemical characterisation of S. verbascifolium extract was carried out. PDI reaction was dependent mainly on singlet oxygen and to a lesser extent, on hydroxyl radicals, through type II and I reactions. Photodegradation experiments revealed that the active principle of the extract was not particularly photolabile. It is noticeable that S. verbascifolium -PDI was more efficient under sunlight as compared to artificial light (total eradication vs. 4 logs decrease upon 120min of sunlight). The balance between oxidant and antioxidant compounds is likely to be masking or unmasking potential PS of plant extracts, but employing the crude extract, the level of photoactivity of S. verbascifolium is similar to some artificial PS upon exposure to sunlight, demonstrating that natural resources can be employed in PDI of bacteria. PMID:24705374

Mamone, L; Di Venosa, G; Gándara, L; Sáenz, D; Vallecorsa, P; Schickinger, S; Rossetti, M V; Batlle, A; Buzzola, F; Casas, A

2014-04-01

14

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

E-print Network

Identification of Surprisingly Diverse Type IV Pili, across a Broad Range of Gram-Positive Bacteria, Pennsylvania, United States of America Abstract Background: In Gram-negative bacteria, type IV pili (TFP) have apparent that Gram-positive bacteria also express type IV pili; however, little is known about

Plotkin, Joshua B.

15

Quorum sensing by peptide pheromones and two component signal transduction systems in Gram-positive bacteria  

Microsoft Academic Search

Cell-density-dependent gene expression appears to be widely spread in bacteria. This quorum-sensing phenomenon has been well established in Gram-negative bacteria, where N-acyl homoserine lactones are the diffusible communication molecules that modulate cell-density-dependent phenotypes. Similarly, a variety of processes are known to be regulated in a cell-density- or growth-phase-dependent manner in Gram-positive bacteria. Examples of such quorum-sensing modes in Gram-positive bacteria

Michiel Kleerebezem; Luis E. N. Quadri; Oscar P. Kuipers; Willem M. de Vos

1997-01-01

16

Pili in Gram-positive bacteria: assembly, involvement in colonization and biofilm development  

PubMed Central

Various cell-surface multisubunit protein polymers, known as pili or fimbriae, have a pivotal role in the colonization of specific host tissues by many pathogenic bacteria. In contrast to Gram-negative bacteria, Gram-positive bacteria assemble pili by a distinct mechanism involving a transpeptidase called sortase. Sortase crosslinks individual pilin monomers and ultimately joins the resulting covalent polymer to the cell-wall peptidoglycan. Here we review current knowledge of this mechanism and the roles of Gram-positive pili in the colonization of specific host tissues, modulation of host immune responses and the development of bacterial biofilms. PMID:18083568

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

2010-01-01

17

Purification Techniques of Bacteriocins from Lactic Acid Bacteria and Other Gram-Positive Bacteria  

NASA Astrophysics Data System (ADS)

The search for new antimicrobial peptides produced by lactic acid ­bacteria and other Gram-positive microorganisms has become an interesting field of research in the past decades. The fact that bacteriocins are active against numerous foodborne and human pathogens, are produced by generally regarded as safe (GRAS) microorganisms, and are readily degraded by proteolytic host systems makes them attractive candidates for biotechnological applications. However, before suggesting or choosing a new bacteriocin for future technology developments, it is necessary to elucidate its biochemical structure and its mode of action, which may be carried out once the bacteriocin is purified to homogeneity. This chapter focuses on describing the main strategies used for the purification of numerous bacteriocins.

Saavedra, Lucila; Sesma, Fernando

18

Rapid method for distinction of gram-negative from gram-positive bacteria  

Microsoft Academic Search

A rapid method for distinction between gram-negative and grampositive bacteria by means of a 3% solution of potassium hydroxide is tested on 71 gram-positive and 55 gram-negative bacterial strains. The method proved reliable with one exception only, a Bacillus macerans strain. That strain was definately gram-negative on staining. Other Bacillus strains were proved gram-positive by the test, even those being

T. Gregersen

1978-01-01

19

New insights into regulation of the tryptophan biosynthetic operon in Gram-positive bacteria.  

PubMed

The tryptophan operon of Bacillus subtilis serves as an excellent model for investigating transcription regulation in Gram-positive bacteria. In this article, we extend this knowledge by analyzing the predicted regulatory regions in the trp operons of other fully sequenced Gram-positive bacteria. Interestingly, it appears that in eight of the organisms examined, transcription of the trp operon appears to be regulated by tandem T-box elements. These regulatory elements have recently been described in the trp operons of two bacterial species. Single T-box elements are commonly found in Gram-positive bacteria in operons encoding aminoacyl tRNA synthetases and proteins performing other functions. Different regulatory mechanisms appear to be associated with variations of trp gene organization within the trp operon. PMID:15953653

Gutierrez-Preciado, A; Jensen, R A; Yanofsky, C; Merino, E

2005-08-01

20

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

21

The use of lysozyme modified with fluorescein for the detection of Gram-positive bacteria.  

PubMed

Lysozyme (1,4-?-N-acetylmuramidase) is commonly applied in the food, medical, and pharmaceutical industries. In this study, we tested a novel application of fluorescein-modified lysozyme (using carboxyfluorescein with a triazine-based coupling reagent) as a new tool for the detection of Gram-positive soil bacteria. The results, obtained by cultivation methods, fluorescence analysis, and laser interferometry, showed that, after optimization, fluorescein-modified lysozyme could be used to evaluate the prevalence of Gram-positive bacteria essential in bioremediation of soils with low pH, such as those degraded by sulfur. PMID:24916601

Arabski, Micha?; Konieczna, Iwona; Tusi?ska, Ewa; W?sik, S?awomir; Relich, Inga; Zaj?c, Krzysztof; Kami?ski, Zbigniew J; Kaca, Wies?aw

2015-01-01

22

Phylogenetic Diversity of Gram-Positive Bacteria Cultured from Marine Sediments? †  

PubMed Central

Major advances in our understanding of marine bacterial diversity have been gained through studies of bacterioplankton, the vast majority of which appear to be gram negative. Less effort has been devoted to studies of bacteria inhabiting marine sediments, yet there is evidence to suggest that gram-positive bacteria comprise a relatively large proportion of these communities. To further expand our understanding of the aerobic gram-positive bacteria present in tropical marine sediments, a culture-dependent approach was applied to sediments collected in the Republic of Palau from the intertidal zone to depths of 500 m. This investigation resulted in the isolation of 1,624 diverse gram-positive bacteria spanning 22 families, including many that appear to represent new taxa. Phylogenetic analysis of 189 representative isolates, based on 16S rRNA gene sequence data, indicated that 124 (65.6%) belonged to the class Actinobacteria while the remaining 65 (34.4%) were members of the class Bacilli. Using a sequence identity value of ?98%, the 189 isolates grouped into 78 operational taxonomic units, of which 29 (37.2%) are likely to represent new taxa. The high degree of phylogenetic novelty observed during this study highlights the fact that a great deal remains to be learned about the diversity of gram-positive bacteria in marine sediments. PMID:17400789

Gontang, Erin A.; Fenical, William; Jensen, Paul R.

2007-01-01

23

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

Microsoft Academic Search

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

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

2001-01-01

24

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

PubMed

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

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

2013-12-01

25

Maturation pathway of nisin and other lantibiotics: post-translationally modified antimicrobial peptides exported by Gram-positive bacteria  

Microsoft Academic Search

Lantibiotics form a family of highly modified peptides which are secreted by several Gram-positive bacteria. They exhibit antimicrobial activity, mainly against other Gram-positive bacteria, by forming pores in the cellular membrane. These antimicrobial peptides are ribosomally synthesized and contain leader peptides which do not show the characteristics of signal sequences. Several amino acid residues of the precursor lantibiotic are enzymatically

Willem M. de Vos; Oscar P. Kuipers; Jan Roelof van der Meer; Roland J. Siezen

1995-01-01

26

Lipoteichoic Acids, Phosphate-Containing Polymers in the Envelope of Gram-Positive Bacteria  

PubMed Central

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

Schneewind, Olaf

2014-01-01

27

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

28

Identification of gram-negative and gram-positive bacteria by fluorescence studies  

NASA Astrophysics Data System (ADS)

Several type strains of bacteria including Vibrio fischeri, Azotobacter vinelandii, Enterobacter cloacae, and Corynebacterium xerosis, were cultured in the laboratory following standard diagnostic protocol based on their individual metabolic strategies. The bacterial cultures were not further treated and they were studied in their pristine state (pure culture - axenic). The fluorescent studies were applied using a continuous wave and a pulsed excitation light sources. Emission and excitation spectra were recorded for the continuous wave excitation and they all show similar spectral features with the exception of the gram positive bacteria showing vibronic structures. The vibrational modes involved in these vibronic bands have energy typical for carbon-carbon vibrations. The fluorescence is quenched in addition of water, even a very thin layer, which confirms that the observed spectral features originate from the outer parts of the bacteria. These results allow to conclude that the fluorescence spectroscopy can be used as a method for studying the membranes of the bacteria and eventually to discriminate between gram positive and gram negative bacteria. The pulsed experiments show that the fluorescence lifetime is in the sub-microsecond range. The results indicate that the observed spectra are superposition of the emission with different lifetimes.

Demchak, Jonathan; Calabrese, Joseph; Tzolov, Marian

2011-03-01

29

Rapid method that aids in distinguishing Gram-positive from Gram-negative anaerobic bacteria.  

PubMed

Several species of anaerobic bacteria display variable Gram stain reactions which often make identification difficult. A simple, rapid method utilizing a 3% solution of potassium hydroxide to distinguish between gram-positive and gram-negative bacterial was tested on 213 strains of anaerobic bacteria representing 19 genera. The Gram stain reaction and KOH test results were compared with the antibiotic disk susceptibilities (vancomycin and colistin) the preliminary grouping of anaerobic bacteria. All three procedures were in agreement for the majority of strains examined. Some strains of clostridia, eubacteria, and bifidobacteria stained gram negative or gram variable; the KOH and antibiotic disk susceptibility tests correctly classified these strains as gram-positive. The KOH test incorrectly grouped some strains of Bacteroides sp., Fusobacterium sp., Leptotrichia buccalis, and Veillonella parvula, but all Gram stain results for these strains were consistent for gram-negative bacteria. The KOH test is a useful supplement to the Gram stain and antibiotic disk susceptibility testing for the initial classification of anaerobic bacteria. PMID:6165736

Halebian, S; Harris, B; Finegold, S M; Rolfe, R D

1981-03-01

30

Critical cell wall hole size for lysis in Gram-positive bacteria  

NASA Astrophysics Data System (ADS)

Gram-positive bacteria transport molecules necessary for their survival through holes in their cell wall. The holes in cell walls need to be large enough to let critical nutrients pass through. However, the cell wall must also function to prevent the bacteria's membrane from protruding through a large hole into the environment and lysing the cell. As such, we hypothesize that there exists a range of cell wall hole sizes that allow for molecule transport but prevent membrane protrusion. Here we develop and analyze a biophysical theory of the response of a Gram-positive cell's membrane to the formation of a hole in the cell wall. We predict a critical hole size in the range 15-24nm beyond which lysis occurs. To test our theory, we measured hole sizes in Streptococcus pyogenes cells undergoing enzymatic lysis via transmission electron microscopy. The measured hole sizes are in strong agreement with our theoretical prediction. Together, the theory and experiments provide a means to quantify the mechanisms of death of Gram-positive cells via enzymatically mediated lysis and provides insight into the range of cell wall hole sizes compatible with bacterial homeostasis.

Mitchell, Gabriel; Wiesenfeld, Kurt; Nelson, Daniel; Weitz, Joshua

2013-03-01

31

Prediction of Cell Wall Sorting Signals in Gram-Positive bacteria with a Hidden Markov Model: Application to Complete genomes  

Microsoft Academic Search

Surface proteins in Gram-positive bacteria are frequently implicated in virulence. We have focused on a group of extracellular cell wall-attached proteins (CWPs), contain- ing an LPXTG motif for cleavage and covalent coupling to peptidoglycan by sortase enzymes. A hidden Markov model (HMM) approach for predicting the LPXTG-anchored cell wall proteins of Gram-positive bacteria was developed and compared against existing methods.

Zoi I. Litou; Pantelis G. Bagos; Konstantinos D. Tsirigos; Theodore D. Liakopoulos; Stavros J. Hamodrakas

2008-01-01

32

Surviving the Acid Test: Responses of Gram-Positive Bacteria to Low pH  

PubMed Central

Gram-positive bacteria possess a myriad of acid resistance systems that can help them to overcome the challenge posed by different acidic environments. In this review the most common mechanisms are described: i.e., the use of proton pumps, the protection or repair of macromolecules, cell membrane changes, production of alkali, induction of pathways by transcriptional regulators, alteration of metabolism, and the role of cell density and cell signaling. We also discuss the reponses of Listeria monocytogenes, Rhodococcus, Mycobacterium, Clostridium perfringens, Staphylococcus aureus, Bacillus cereus, oral streptococci, and lactic acid bacteria to acidic environments and outline ways in which this knowledge has been or may be used to either aid or prevent bacterial survival in low-pH environments. PMID:12966143

Cotter, Paul D.; Hill, Colin

2003-01-01

33

Two Active Forms of UDP-N-Acetylglucosamine Enolpyruvyl Transferase in Gram-Positive Bacteria  

PubMed Central

Gene sequences encoding the enzymes UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) from many bacterial sources were analyzed. It was shown that whereas gram-negative bacteria have only one murA gene, gram-positive bacteria have two distinct genes encoding these enzymes which have possibly arisen from gene duplication. The two murA genes of the gram-positive organism Streptococcus pneumoniae were studied further. Each of the murA genes was individually inactivated by allelic replacement. In each case, the organism was viable despite losing one of its murA genes. However, when attempts were made to construct a double-deletion strain, no mutants were obtained. This indicates that both genes encode active enzymes that can substitute for each other, but that the presence of a MurA function is essential to the organism. The two genes were further cloned and overexpressed, and the enzymes they encode were purified. Both enzymes catalyzed the transfer of enolpyruvate from phosphoenolpyruvate to UDP-N-acetylglucosamine, confirming they are both active UDP-N-acetylglucosamine enolpyruvyl transferases. The catalytic parameters of the two enzymes were similar, and they were both inhibited by the antibiotic fosfomycin. PMID:10894720

Du, Wensheng; Brown, James R.; Sylvester, Daniel R.; Huang, Jianzhong; Chalker, Alison F.; So, Chi Y.; Holmes, David J.; Payne, David J.; Wallis, Nicola G.

2000-01-01

34

Two active forms of UDP-N-acetylglucosamine enolpyruvyl transferase in gram-positive bacteria.  

PubMed

Gene sequences encoding the enzymes UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) from many bacterial sources were analyzed. It was shown that whereas gram-negative bacteria have only one murA gene, gram-positive bacteria have two distinct genes encoding these enzymes which have possibly arisen from gene duplication. The two murA genes of the gram-positive organism Streptococcus pneumoniae were studied further. Each of the murA genes was individually inactivated by allelic replacement. In each case, the organism was viable despite losing one of its murA genes. However, when attempts were made to construct a double-deletion strain, no mutants were obtained. This indicates that both genes encode active enzymes that can substitute for each other, but that the presence of a MurA function is essential to the organism. The two genes were further cloned and overexpressed, and the enzymes they encode were purified. Both enzymes catalyzed the transfer of enolpyruvate from phosphoenolpyruvate to UDP-N-acetylglucosamine, confirming they are both active UDP-N-acetylglucosamine enolpyruvyl transferases. The catalytic parameters of the two enzymes were similar, and they were both inhibited by the antibiotic fosfomycin. PMID:10894720

Du, W; Brown, J R; Sylvester, D R; Huang, J; Chalker, A F; So, C Y; Holmes, D J; Payne, D J; Wallis, N G

2000-08-01

35

Optimization of Fluorescent Tools for Cell Biology Studies in Gram-Positive Bacteria  

PubMed Central

The understanding of how Gram-positive bacteria divide and ensure the correct localization of different molecular machineries, such as those involved in the synthesis of the bacterial cell surface, is crucial to design strategies to fight bacterial infections. In order to determine the correct subcellular localization of fluorescent proteins in Streptococcus pneumoniae, we have previously described tools to express derivatives of four fluorescent proteins, mCherry, Citrine, CFP and GFP, to levels that allow visualization by fluorescence microscopy, by fusing the first ten amino acids of the S. pneumoniae protein Wze (the i-tag), upstream of the fluorescent protein. Here, we report that these tools can also be used in other Gram-positive bacteria, namely Lactococcus lactis, Staphylococcus aureus and Bacillus subtilis, possibly due to optimized translation rates. Additionally, we have optimized the i-tag by testing the effect of the first ten amino acids of other pneumococcal proteins in the increased expression of the fluorescent protein Citrine. We found that manipulating the structure and stability of the 5? end of the mRNA molecule, which may influence the accessibility of the ribosome, is determinant to ensure the expression of a strong fluorescent signal. PMID:25464377

Henriques, Mafalda X.; Gomes, João Paulo; Filipe, Sérgio R.

2014-01-01

36

Peptidoglycan architecture of Gram-positive bacteria by solid-state NMR.  

PubMed

Peptidoglycan is an essential component of cell wall in Gram-positive bacteria with unknown architecture. In this review, we summarize solid-state NMR approaches to address some of the unknowns in the Gram-positive bacteria peptidoglycan architecture: 1) peptidoglycan backbone conformation, 2) PG-lattice structure, 3) variations in the peptidoglycan architecture and composition, 4) the effects of peptidoglycan bridge-length on the peptidoglycan architecture in Fem mutants, 5) the orientation of glycan strands with respect to the membrane, and 6) the relationship between the peptidoglycan structure and the glycopeptide antibiotic mode of action. Solid-state NMR analyses of Staphylococcus aureus cell wall show that peptidoglycan chains are surprisingly ordered and densely packed. The peptidoglycan disaccharide backbone adopts 4-fold screw helical symmetry with the disaccharide unit periodicity of 40Å. Peptidoglycan lattice in the S. aureus cell wall is formed by cross-linked PG stems that have parallel orientations. The structural characterization of Fem-mutants of S. aureus with varying lengths of bridge structures suggests that the PG-bridge length is an important determining factor for the PG architecture. This article is part of a Special Issue entitled: NMR Spectroscopy for Atomistic Views of Biomembranes and Cell Surfaces. Guest Editors: Lynette Cegelski and David P. Weliky. PMID:24915020

Kim, Sung Joon; Chang, James; Singh, Manmilan

2015-01-01

37

Chitosan augments photodynamic inactivation of gram-positive and gram-negative bacteria.  

PubMed

Antimicrobial photodynamic inactivation (PDI) was shown to be a promising treatment modality for microbial infections. This study explores the effect of chitosan, a polycationic biopolymer, in increasing the PDI efficacy against Gram-positive bacteria, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, and methicillin-resistant S. aureus (MRSA), as well as the Gram-negative bacteria Pseudomonas aeruginosa and Acinetobacter baumannii. Chitosan at <0.1% was included in the antibacterial process either by coincubation with hematoporphyrin (Hp) and subjection to light exposure to induce the PDI effect or by addition after PDI and further incubation for 30 min. Under conditions in which Hp-PDI killed the microbe on a 2- to 4-log scale, treatment with chitosan at concentrations of as low as 0.025% for a further 30 min completely eradicated the bacteria (which were originally at ?10(8) CFU/ml). Similar results were also found with toluidine blue O (TBO)-mediated PDI in planktonic and biofilm cells. However, without PDI treatment, chitosan alone did not exert significant antimicrobial activity with 30 min of incubation, suggesting that the potentiated effect of chitosan worked after the bacterial damage induced by PDI. Further studies indicated that the potentiated PDI effect of chitosan was related to the level of PDI damage and the deacetylation level of the chitosan. These results indicate that the combination of PDI and chitosan is quite promising for eradicating microbial infections. PMID:21282440

Tsai, Tsuimin; Chien, Hsiung-Fei; Wang, Tze-Hsien; Huang, Ching-Tsan; Ker, Yaw-Bee; Chen, Chin-Tin

2011-05-01

38

In Vitro Activities of Membrane-Active Peptides against Gram-Positive and Gram-Negative Aerobic Bacteria  

Microsoft Academic Search

Four peptides, cecropin P1, magainin II, indolicidin, and ranalexin, were evaluated against 202 clinical isolates of gram-positive and gram-negative aerobic bacteria by a microbroth dilution method. The gram- negative isolates were more susceptible to cecropin P1. Ranalexin was the most active compound against the gram-positive strains. The bactericidal activity of each peptide was equivalent to, or 1 dilution above, the

A. GIACOMETTI; O. CIRIONI; G. GREGANTI; M. QUARTA; G. SCALISE

1998-01-01

39

?, a new subunit of RNA polymerase found in gram-positive bacteria.  

PubMed

RNA polymerase in bacteria is a multisubunit protein complex that is essential for gene expression. We have identified a new subunit of RNA polymerase present in the high-A+T Firmicutes phylum of Gram-positive bacteria and have named it ?. Previously ? had been identified as a small protein (?1) that copurified with RNA polymerase. We have solved the structure of ? by X-ray crystallography and show that it is not an ? subunit. Rather, ? bears remarkable similarity to the Gp2 family of phage proteins involved in the inhibition of host cell transcription following infection. Deletion of ? shows no phenotype and has no effect on the transcriptional profile of the cell. Determination of the location of ? within the assembly of RNA polymerase core by single-particle analysis suggests that it binds toward the downstream side of the DNA binding cleft. Due to the structural similarity of ? with Gp2 and the fact they bind similar regions of RNA polymerase, we hypothesize that ? may serve a role in protection from phage infection. PMID:25092033

Keller, Andrew N; Yang, Xiao; Wiedermannová, Jana; Delumeau, Olivier; Krásný, Libor; Lewis, Peter J

2014-10-01

40

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

PubMed Central

The cell wall envelopes of gram-positive bacteria represent a surface organelle that not only functions as a cytoskeletal element but also promotes interactions between bacteria and their environment. Cell wall peptidoglycan is covalently and noncovalently decorated with teichoic acids, polysaccharides, and proteins. The sum of these molecular decorations provides bacterial envelopes with species- and strain-specific properties that are ultimately responsible for bacterial virulence, interactions with host immune systems, and the development of disease symptoms or successful outcomes of infections. Surface proteins typically carry two topogenic sequences, i.e., N-terminal signal peptides and C-terminal sorting signals. Sortases catalyze a transpeptidation reaction by first cleaving a surface protein substrate at the cell wall sorting signal. The resulting acyl enzyme intermediates between sortases and their substrates are then resolved by the nucleophilic attack of amino groups, typically provided by the cell wall cross bridges of peptidoglycan precursors. The surface protein linked to peptidoglycan is then incorporated into the envelope and displayed on the microbial surface. This review focuses on the mechanisms of surface protein anchoring to the cell wall envelope by sortases and the role that these enzymes play in bacterial physiology and pathogenesis. PMID:16524923

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

2006-01-01

41

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

EPA Science Inventory

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

42

[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

43

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

PubMed Central

Background We infected freshly isolated human peripheral monocytes with live bacteria of three clinically important gram-positive bacterial species, Staphylococcus aureus, Streptococcus pneumoniae and Listeria monocytogenes and studied the ensuing early transcriptional response using expression microarrays. Thus the observed response was unbiased by signals originating from other helper and effector cells of the host and was not limited to induction by solitary bacterial constituents. Results Activation of monocytes was demonstrated by the upregulation of chemokine rather than interleukin genes except for the prominent expression of interleukin 23, marking it as the early lead cytokine. This activation was accompanied by cytoskeleton rearrangement signals and a general anti-oxidative stress and anti-apoptotic reaction. Remarkably, the expression profiles also provide evidence that monocytes participate in the regulation of angiogenesis and endothelial function in response to these pathogens. Conclusion Regardless of the invasion properties and survival mechanisms of the pathogens used, we found that the early response comprised of a consistent and common response. The common response was hallmarked by the upregulation of interleukin 23, a rather unexpected finding regarding Listeria infection, as this cytokine has been linked primarily to the control of extracellular bacterial dissemination. PMID:21044323

2010-01-01

44

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

45

Identification of a structural determinant for resistance to ?-lactam antibiotics in Gram-positive bacteria  

PubMed Central

Streptococcus pneumoniae is the main causal agent of pathologies that are increasingly resistant to antibiotic treatment. Clinical resistance of S. pneumoniae to ?-lactam antibiotics is linked to multiple mutations of high molecular mass penicillin-binding proteins (H-PBPs), essential enzymes involved in the final steps of bacterial cell wall synthesis. H-PBPs from resistant bacteria have a reduced affinity for ?-lactam and a decreased hydrolytic activity on substrate analogues. In S. pneumoniae, the gene coding for one of these H-PBPs, PBP2x, is located in the cell division cluster (DCW). We present here structural evidence linking multiple ?-lactam resistance to amino acid substitutions in PBP2x within a buried cavity near the catalytic site that contains a structural water molecule. Site-directed mutation of amino acids in contact with this water molecule in the “sensitive” form of PBP2x produces mutants similar, in terms of ?-lactam affinity and substrate hydrolysis, to altered PBP2x produced in resistant clinical isolates. A reverse mutation in a PBP2x variant from a clinically important resistant clone increases the acylation efficiency for ?-lactams and substrate analogues. Furthermore, amino acid residues in contact with the structural water molecule are conserved in the equivalent H-PBPs of pathogenic Gram-positive cocci. We suggest that, probably via a local structural modification, the partial or complete loss of this water molecule reduces the acylation efficiency of PBP2x substrates to a point at which cell wall synthesis still occurs, but the sensitivity to therapeutic concentrations of ?-lactam antibiotics is lost. PMID:9811812

Mouz, N.; Gordon, E.; Di Guilmi, A.-M.; Petit, I.; Pétillot, Y.; Dupont, Y.; Hakenbeck, R.; Vernet, T.; Dideberg, O.

1998-01-01

46

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

47

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

PubMed

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 MRSA or VRE was 24.7% (174/705 samples) compared with 4.9% (89/1827 samples) for multi-resistant Gram-negative bacteria (P<0.001). Gram-positive bacteria were isolated more frequently than Gram-negatives from the hands of patients (P<0.001) and hospital personnel (P=0.1145). Environmental contamination did not differ between the intensive care units (ICUs) and the general wards (GWs), which is noteworthy because our ICUs are routinely disinfected twice a day, whereas GWs are cleaned just once a day with detergent. Current guidelines for the prevention of spread of multi-resistant bacteria in the hospital setting do not distinguish between Gram-positive and Gram-negative isolates. Our results suggest that the inanimate environment serves as a secondary source for MRSA and VRE, but less so for Gram-negative bacteria. Thus, strict contact isolation in a single room with complete barrier precautions is recommended for MRSA or VRE; however, for multi-resistant Gram-negative bacteria, contact isolation with barrier precautions for close contact but without a single room seems sufficient. This benefits not only the patients, but also the hospital by removing some of the strain placed on already over-stretched resources. PMID:15003666

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

2004-03-01

48

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

PubMed

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

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

2013-01-01

49

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

50

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

PubMed

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

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

2014-08-01

51

Production of a bacteriocin by a poultry derived Campylobacter jejuni isolate with antimicrobial activity against Clostridium perfringens and other Gram positive bacteria.  

Technology Transfer Automated Retrieval System (TEKTRAN)

We have purified a bacteriocin peptide (termed CUV-3), produced by a poultry cecal isolate of Campylobacter jejuni (strain CUV-3) with inhibitory activity against Gram positive bacteria including Clostridium perfringens (38 strains), Staphylococcus aureus, Staphylococcus epidermidis and Listeria mon...

52

Classification of gram-positive and gram-negative foodborne pathogenic bacteria with hyperspectral microscope imaging  

Technology Transfer Automated Retrieval System (TEKTRAN)

Optical method with hyperspectral microscope imaging (HMI) has potential for identification of foodborne pathogenic bacteria from microcolonies rapidly with a cell level. A HMI system that provides both spatial and spectral information could be an effective tool for analyzing spectral characteristic...

53

Hyperspectral microscope imaging methods to classify gram-positive and gram-negative foodborne pathogenic bacteria  

Technology Transfer Automated Retrieval System (TEKTRAN)

An acousto-optic tunable filter-based hyperspectral microscope imaging method has potential for identification of foodborne pathogenic bacteria from microcolony rapidly with a single cell level. We have successfully developed the method to acquire quality hyperspectral microscopic images from variou...

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

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

56

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

PubMed

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

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

1991-02-01

57

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-Más, María Ángeles; Campoy, Susana; Toledo-Arana, Alejandro; Monedero, Vicente; Lasa, Íñigo; Novick, Richard P.; Christie, Gail E.; Penadés, José R.

2013-01-01

58

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

59

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

Microsoft Academic Search

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

LIEVE VAN MELLAERT; Jozef Anné

60

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

NASA Astrophysics Data System (ADS)

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

Fowle, David A.; Fein, Jeremy B.

1999-10-01

61

Stronger T Cell Immunogenicity of Ovalbumin Expressed Intracellularly in Gram-Negative than in Gram-Positive Bacteria  

PubMed Central

This study aimed to clarify whether Gram-positive (G+) and Gram-negative (G?) bacteria affect antigen-presenting cells differently and thereby influence the immunogenicity of proteins they express. Lactobacilli, lactococci and Escherichia coli strains were transformed with plasmids conferring intracellular ovalbumin (OVA) production. Murine splenic antigen presenting cells (APCs) were pulsed with washed and UV-inactivated OVA-producing bacteria, control bacteria, or soluble OVA. The ability of the APCs to activate OVA-specific DO11.10 CD4+ T cells was assessed by measurments of T cell proliferation and cytokine (IFN-?, IL-13, IL-17, IL-10) production. OVA expressed within E. coli was strongly immunogenic, since 500 times higher concentrations of soluble OVA were needed to achieve a similar level of OVA-specific T cell proliferation. Furthermore, T cells responding to soluble OVA produced mainly IL-13, while T cells responding to E. coli-expressed OVA produced high levels of both IFN-? and IL-13. Compared to E. coli, G+ lactobacilli and lactococci were poor inducers of OVA-specific T cell proliferation and cytokine production, despite efficient intracellular expression and production of OVA and despite being efficiently phagocytosed. These results demonstrate a pronounced difference in immunogenicity of intracellular antigens in G+ and G? bacteria and may be relevant for the use of bacterial carriers in vaccine development. PMID:23741469

Martner, Anna; Östman, Sofia; Lundin, Samuel; Rask, Carola; Björnsson, Viktor; Telemo, Esbjörn; Collins, L. Vincent; Axelsson, Lars; Wold, Agnes E.

2013-01-01

62

A Newly Discovered Bacteroides Conjugative Transposon, CTnGERM1, Contains Genes Also Found in Gram-Positive Bacteria  

PubMed Central

Results of a recent study of antibiotic resistance genes in human colonic Bacteroides strains suggested that gene transfer events between members of this genus are fairly common. The identification of Bacteroides isolates that carried an erythromycin resistance gene, ermG, whose DNA sequence was 99% identical to that of an ermG gene found previously only in gram-positive bacteria raised the further possibility that conjugal elements were moving into Bacteroides species from other genera. Six of seven ermG-containing Bacteroides strains tested were able to transfer ermG by conjugation. One of these strains was chosen for further investigation. Results of pulsed-field gel electrophoresis experiments showed that the conjugal element carrying ermG in this strain is an integrated element about 75 kb in size. Thus, the element appears to be a conjugative transposon (CTn) and was designated CTnGERM1. CTnGERM1 proved to be unrelated to the predominant type of CTn found in Bacteroides isolates—CTns of the CTnERL/CTnDOT family—which sometimes carry another type of erm gene, ermF. A 19-kbp segment of DNA from CTnGERM1 was cloned and sequenced. A 10-kbp portion of this segment hybridized not only to DNA from all the ermG-containing strains but also to DNA from strains that did not carry ermG. Thus, CTnGERM1 seems to be part of a family of CTns, some of which have acquired ermG. The percentage of G+C content of the ermG region was significantly lower than that of the chromosome of Bacteroides species—an indication that CTnGERM1 may have entered Bacteroides strains from some other bacterial genus. A survey of strains isolated before 1970 and after 1990 suggests that the CTnGERM1 type of CTn entered Bacteroides species relatively recently. One of the genes located upstream of ermG encoded a protein that had 85% amino acid sequence identity with a macrolide efflux pump, MefA, from Streptococcus pyogenes. Our having found >90% sequence identity of two upstream genes, including mefA, and the remnants of two transposon-carried genes downstream of ermG with genes found previously only in gram-positive bacteria raises the possibility that gram-positive bacteria could have been the origin of CTnGERM1. PMID:12902247

Wang, Yanping; Wang, Gui-Rong; Shelby, Aikiesha; Shoemaker, Nadja B.; Salyers, Abigail A.

2003-01-01

63

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

PubMed

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

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

2013-07-01

64

Evaluation of the Verigene Gram-Positive Blood Culture Nucleic Acid Test for Rapid Detection of Bacteria and Resistance Determinants  

PubMed Central

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

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

2013-01-01

65

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

PubMed Central

Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they may be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or anthraquinone-2,6-disulfonate (AQDS), an analog of the redox active components of humic substances. The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin-shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS, and that several MHCs are localized to the cell wall or cell surface. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants, suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results provide unique direct evidence for cell wall-associated cytochromes and support MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium. PMID:22307634

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

2012-01-01

66

The Transfer Origin for Bacteroides Mobilizable Transposon Tn4555 Is Related to a Plasmid Family from Gram-Positive Bacteria  

PubMed Central

Conjugal transfer of Bacteroides mobilizable transposon Tn4555 was examined with an Escherichia coli-based assay system. It was shown that mobilization required the cis-acting oriTTn region and that the Tn4555 mobATn gene and RK231 must be present in trans. With alkaline agarose gel electrophoresis and filter blot hybridizations, it was shown that at oriTTn there was a site- and strand-specific cleavage event that was dependent on mobATn. The 5? end of this cleavage site was mapped by primer extension, and the nucleotide sequence surrounding the site had homology to a family of oriT nick sites found in mobilizable plasmids of gram-positive bacteria. Removal of the nick site by deletion of 18 bp surrounding the site resulted in a significant loss of transfer activity. PMID:9440538

Smith, C. Jeffrey; Parker, Anita C.

1998-01-01

67

Pharmacodynamics of Telavancin (TD-6424), a Novel Bactericidal Agent, against Gram-Positive Bacteria  

PubMed Central

Telavancin (TD-6424) is a novel lipoglycopeptide that produces rapid and concentration-dependent killing of clinically relevant gram-positive organisms in vitro. The present studies evaluated the in vivo pharmacodynamics of telavancin in the mouse neutropenic thigh (MNT) and mouse subcutaneous infection (MSI) animal models. Pharmacokinetic-pharmacodynamic studies in the MNT model demonstrated that the 24-h area under the concentration-time curve (AUC)/MIC ratio was the best predictor of efficacy. Telavancin produced dose-dependent reduction of thigh titers of several organisms, including methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA), penicillin-susceptible and -resistant strains of Streptococcus pneumoniae, and vancomycin-resistant Enterococcus faecalis. The 50% effective dose (ED50) estimates for telavancin ranged from 0.5 to 6.6 mg/kg of body weight (administered intravenously), and titers were reduced by up to 3 log10 CFU/g from pretreatment values. Against MRSA ATCC 33591, telavancin was 4- and 30-fold more potent (on an ED50 basis) than vancomycin and linezolid, respectively. Against MSSA ATCC 13709, telavancin was 16- and 40-fold more potent than vancomycin and nafcillin, respectively. Telavancin, vancomycin, and linezolid were all efficacious and more potent against MRSA ATCC 33591 in the MSI model compared to the MNT model. This deviation in potency was, however, disproportionately greater for vancomycin and linezolid than for telavancin, suggesting that activity of telavancin is less affected by the immune status. The findings of these studies collectively suggest that once-daily dosing of telavancin may provide an effective approach for the treatment of clinically relevant infections with gram-positive organisms. PMID:15273119

Hegde, Sharath S.; Reyes, Noe; Wiens, Tania; Vanasse, Nicole; Skinner, Robert; McCullough, Julia; Kaniga, Koné; Pace, John; Thomas, Roger; Shaw, Jeng-Pyng; Obedencio, Glen; Judice, J. Kevin

2004-01-01

68

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

69

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

70

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

71

Mobilizable Rolling-Circle Replicating Plasmids from Gram-Positive Bacteria: A Low-Cost Conjugative Transfer  

PubMed Central

Chapter summary Conjugation is a key mechanism for horizontal gene transfer in bacteria. Some plasmids are not self-transmissible but can be mobilized by functions encoded in trans provided by other auxiliary conjugative elements. Although the transfer efficiency of mobilizable plasmids is usually lower than that of conjugative elements, mobilizable plasmidsare more frequently found in nature. In this sense, replication and mobilization can be considered as important mechanisms influencing plasmid promiscuity. Here we review the present available information on two families of small mobilizable plasmids from Gram-positive bacteria that replicate via the rolling-circle mechanism. One of these families, represented by the streptococcal plasmid pMV158, is an interesting model since it contains a specific mobilization module (MOBV) that is widely distributed among mobilizable plasmids. We discuss a mechanism in which the promiscuity of the pMV158 replicon is based on the presence of two origins of lagging strand synthesis. The current strategies to assess plasmid transfer efficiency as well as to inhibit conjugative plasmid transfer are presented. Some applications of these plasmids as biotechnological tools are also reviewed. PMID:25606350

Fernández-López, Cris; Bravo, Alicia; Ruiz-Cruz, Sofía; Solano-Collado, Virtu; Garsin, Danielle A.; Lorenzo-Díaz, Fabián; Espinosa, Manuel

2014-01-01

72

Genome-wide gene order distances support clustering the gram-positive bacteria  

PubMed Central

Initially using 143 genomes, we developed a method for calculating the pair-wise distance between prokaryotic genomes using a Monte Carlo method to estimate the conservation of gene order. The method was based on repeatedly selecting five or six non-adjacent random orthologs from each of two genomes and determining if the chosen orthologs were in the same order. The raw distances were then corrected for gene order convergence using an adaptation of the Jukes-Cantor model, as well as using the common distance correction D? = ?ln(1-D). First, we compared the distances found via the order of six orthologs to distances found based on ortholog gene content and small subunit rRNA sequences. The Jukes-Cantor gene order distances are reasonably well correlated with the divergence of rRNA (R2 = 0.24), especially at rRNA Jukes-Cantor distances of less than 0.2 (R2 = 0.52). Gene content is only weakly correlated with rRNA divergence (R2 = 0.04) over all distances, however, it is especially strongly correlated at rRNA Jukes-Cantor distances of less than 0.1 (R2 = 0.67). This initial work suggests that gene order may be useful in conjunction with other methods to help understand the relatedness of genomes. Using the gene order distances in 143 genomes, the relations of prokaryotes were studied using neighbor joining and agreement subtrees. We then repeated our study of the relations of prokaryotes using gene order in 172 complete genomes better representing a wider-diversity of prokaryotes. Consistently, our trees show the Actinobacteria as a sister group to the bulk of the Firmicutes. In fact, the robustness of gene order support was found to be considerably greater for uniting these two phyla than for uniting any of the proteobacterial classes together. The results are supportive of the idea that Actinobacteria and Firmicutes are closely related, which in turn implies a single origin for the gram-positive cell. PMID:25653643

House, Christopher H.; Pellegrini, Matteo; Fitz-Gibbon, Sorel T.

2015-01-01

73

AFM study of the differential inhibitory effects of the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) against Gram-positive and Gram-negative bacteria.  

PubMed

(-)-Epigallocatechin-3-gallate (EGCG), a main constituent of tea catechins, affects Gram-positive and Gram-negative bacteria differently; however, the underlying mechanisms are not clearly understood. Atomic force microscopy (AFM) was used to compare morphological alterations in Gram-positive and Gram-negative bacteria induced by EGCG and by H(2)O(2) at sub-minimum inhibitory concentrations (MICs). EGCG initially induced aggregates in the cell envelopes of Staphylococcus aureus and eventually caused cell lysis, which was not observed in cells treated with H(2)O(2). It initially induced nanoscale perforations or microscale grooves in the cell envelopes of Escherichia coli O157:H7 which eventually disappeared, similar to E. coli cells treated with H(2)O(2). An E. coli O157:H7 tpx mutant, with a defect in thioredoxin-dependent thiol peroxidase (Tpx), was more severely damaged by EGCG when compared with its wild type. Similar differing effects were observed in other Gram-positive and Gram-negative bacteria when exposed to EGCG; it caused aggregated in Streptococcus mutans, while it caused grooves in Pseudomonas aeruginosa. AFM results suggest that the major morphological changes of Gram-negative bacterial cell walls induced by EGCG depend on H(2)O(2) release. This is not the case for Gram-positive bacteria. Oxidative stress in Gram-negative bacteria induced by EGCG was confirmed by flow cytometry. PMID:22029921

Cui, Y; Oh, Y J; Lim, J; Youn, M; Lee, I; Pak, H K; Park, W; Jo, W; Park, S

2012-02-01

74

ppGpp analogues inhibit synthetase activity of Rel proteins from Gram-negative and Gram-positive bacteria.  

PubMed

A prominent feature of the stringent response is the accumulation of two unusual phosphorylated derivatives of GTP and GDP (pppGpp: 5'-triphosphate-3'-diphosphate, and ppGpp: 5'-3'-bis-diphosphate), collectively called (p)ppGpp, within a few seconds after the onset of amino-acid starvation. The synthesis of these 'alarmone' compounds is catalyzed by RelA homologues. Other features of the stringent response include inhibition of stable RNA synthesis and modulation of transcription, replication, and translation. (p)ppGpp accumulation is important for virulence induction, differentiation and antibiotic resistance. We have synthesized a group of (p)ppGpp analogues and tested them as competitive inhibitors of Rel proteins in vitro. 2'-Deoxyguanosine-3'-5'-di(methylene bisphosphonate) [compound (10)] was found as an inhibitor that reduces ppGpp formation in both Gram-negative and Gram-positive bacteria. In silico docking together with competitive inhibition analysis suggests that compound (10) inhibits activity of Rel proteins by competing with GTP/GDP for its binding site. As Rel proteins are completely absent in mammalians, this appears to be a very attractive approach for the development of novel antibacterial agents. PMID:20483622

Wexselblatt, Ezequiel; Katzhendler, Jehoshua; Saleem-Batcha, Raspudin; Hansen, Guido; Hilgenfeld, Rolf; Glaser, Gad; Vidavski, Roee R

2010-06-15

75

A Continuum of Anionic Charge: Structures and Functions of d-Alanyl-Teichoic Acids in Gram-Positive Bacteria  

PubMed Central

Teichoic acids (TAs) are major wall and membrane components of most gram-positive bacteria. With few exceptions, they are polymers of glycerol-phosphate or ribitol-phosphate to which are attached glycosyl and d-alanyl ester residues. Wall TA is attached to peptidoglycan via a linkage unit, whereas lipoteichoic acid is attached to glycolipid intercalated in the membrane. Together with peptidoglycan, these polymers make up a polyanionic matrix that functions in (i) cation homeostasis; (ii) trafficking of ions, nutrients, proteins, and antibiotics; (iii) regulation of autolysins; and (iv) presentation of envelope proteins. The esterification of TAs with d-alanyl esters provides a means of modulating the net anionic charge, determining the cationic binding capacity, and displaying cations in the wall. This review addresses the structures and functions of d-alanyl-TAs, the d-alanylation system encoded by the dlt operon, and the roles of TAs in cell growth. The importance of dlt in the physiology of many organisms is illustrated by the variety of mutant phenotypes. In addition, advances in our understanding of d-alanyl ester function in virulence and host-mediated responses have been made possible through targeted mutagenesis of dlt. Studies of the mechanism of d-alanylation have identified two potential targets of antibacterial action and provided possible screening reactions for designing novel agents targeted to d-alanyl-TA synthesis. PMID:14665680

Neuhaus, Francis C.; Baddiley, James

2003-01-01

76

Gram-Positive Nickel Resistant Bacteria Isolated from Riparian Sediments Contaminated with Ni and U on the Savannah River Site  

NASA Astrophysics Data System (ADS)

The natural attenuation of pollutants in riparian and wetland systems is driven in large part by the services provided by the diverse microbial communities that thrive in these nutritionally and chemically complex environments. For co-contaminated systems, the presence of heavy metals at excessive levels may alter the structure and function of microbial communities that are essential for the immobilization of inorganics and degradation of organic contaminants. We examined riparian sediments heavily contaminated with U and Ni (1000's of mg/kg) from a small stream on the U.S. Department of Energy's Savannah River Site that received metallurgical process effluents wastewater over a thirty-year period associated with the production of nuclear materials. Four gram positive bacteria were isolated that displayed marked resistance (5000 mg/kg) to Ni relative to organisms from uncontaminated control locations: Arthrobacter oxydans, Streptomyces galbus, Streptomyces aureofaciens, and Kitasatospora cystarginea. The metal resistance of S. aureofaciens and K. cystarginea was further characterized in growth experiments for resistance to other metals. Ongoing geochemical characterization of U and Ni in terms of solid phase partitioning and aqueous phase speciation and solubility indicate that Ni is more chemically labile and, by extension, bioavailable than U in these aged-contaminated sediments. Accordingly, the isolation of Ni resistant organisms is consistent with greater selective pressure from Ni as a result of its greater bioavailability. These results are placed in context of environmental management and remediation of co-contaminated, biogeochemically complex environments.

Sowder, A. G.; Khijniak, T. V.; van Nostrand, J.; Bertsch, P. M.; Morris, P. J.

2002-12-01

77

Identification of a structural determinant for resistance to beta-lactam antibiotics in Gram-positive bacteria.  

PubMed

Streptococcus pneumoniae is the main causal agent of pathologies that are increasingly resistant to antibiotic treatment. Clinical resistance of S. pneumoniae to beta-lactam antibiotics is linked to multiple mutations of high molecular mass penicillin-binding proteins (H-PBPs), essential enzymes involved in the final steps of bacterial cell wall synthesis. H-PBPs from resistant bacteria have a reduced affinity for beta-lactam and a decreased hydrolytic activity on substrate analogues. In S. pneumoniae, the gene coding for one of these H-PBPs, PBP2x, is located in the cell division cluster (DCW). We present here structural evidence linking multiple beta-lactam resistance to amino acid substitutions in PBP2x within a buried cavity near the catalytic site that contains a structural water molecule. Site-directed mutation of amino acids in contact with this water molecule in the "sensitive" form of PBP2x produces mutants similar, in terms of beta-lactam affinity and substrate hydrolysis, to altered PBP2x produced in resistant clinical isolates. A reverse mutation in a PBP2x variant from a clinically important resistant clone increases the acylation efficiency for beta-lactams and substrate analogues. Furthermore, amino acid residues in contact with the structural water molecule are conserved in the equivalent H-PBPs of pathogenic Gram-positive cocci. We suggest that, probably via a local structural modification, the partial or complete loss of this water molecule reduces the acylation efficiency of PBP2x substrates to a point at which cell wall synthesis still occurs, but the sensitivity to therapeutic concentrations of beta-lactam antibiotics is lost. PMID:9811812

Mouz, N; Gordon, E; Di Guilmi, A M; Petit, I; Pétillot, Y; Dupont, Y; Hakenbeck, R; Vernet, T; Dideberg, O

1998-11-10

78

Comparison of antimicrobial pharmacokinetic/pharmacodynamic breakpoints with EUCAST and CLSI clinical breakpoints for Gram-positive bacteria.  

PubMed

This study compared the susceptibility breakpoints based on pharmacokinetic/pharmacodynamic (PK/PD) models and Monte Carlo simulation with those defined by the Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) for antibiotics used for the treatment of infections caused by Gram-positive bacteria. A secondary objective was to evaluate the probability of achieving the PK/PD target associated with the success of antimicrobial therapy. A 10,000-subject Monte Carlo simulation was executed to evaluate 13 antimicrobials (47 intravenous dosing regimens). Susceptibility data were extracted from the British Society for Antimicrobial Chemotherapy database for bacteraemia isolates. The probability of target attainment and the cumulative fraction of response (CFR) were calculated. No antibiotic was predicted to be effective (CFR?90%) against all microorganisms. The PK/PD susceptibility breakpoints were also estimated and were compared with CLSI and EUCAST breakpoints. The percentages of strains affected by breakpoint discrepancies were calculated. In the case of ?-lactams, breakpoint discrepancies affected <15% of strains. However, higher differences were detected for low doses of vancomycin, daptomycin and linezolid, with PK/PD breakpoints being lower than those defined by the CLSI and EUCAST. If this occurs, an isolate will be considered susceptible based on CLSI and EUCAST breakpoints although the PK/PD analysis predicts failure, which may explain treatment failures reported in the literature. This study reinforces the idea of considering not only the antimicrobial activity but also the dosing regimen to increase the probability of clinical success of an antimicrobial treatment. PMID:22921422

Asín, Eduardo; Isla, Arantxazu; Canut, Andrés; Rodríguez Gascón, Alicia

2012-10-01

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

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

PubMed Central

Background A preparation method for quantification of bacteria in tissues is obligatory to reduce tissue mass, concentrate the target, purify, remove inhibitory substances and to achieve constant target recovery rates. No preparation method has been available until now for a high mass of tissue applicable for routine use and analytical veterinary diagnostics. Results This study describes an easy-to-use tissue preparation protocol to quantify Gram-positive bacteria from a large volume of tissue matrix. A previously published sample preparation method (Matrix-Lysis) from food science was successfully adapted for clinical use on tissues from pigs, including cerebrum, spinal cord, lung, liver, ileum, colon, caecum, kidney and muscle tissue. This tissue preparation method now permits quantification of pathogens from 5 g of organic matrix, which is a 20–200 fold increase by weight compared to other methods. It is based on solubilization of the sample matrix with either a chaotrope plus detergent or divalent salts as solubilization agents. The method was designed as a modular system, offering the possibility to change lysis buffers, according to tissue solubilization characteristics and the intended detection method (molecular or culture). Using Listeria monocytogenes as model organism, viable cell quantification or DNA extraction and quantitative real-time PCR were performed after Matrix-Lysis to determine recovery rates and detection limit (LOD). The adapted Matrix-Lysis protocol resulted in high recovery rates (mean value: 76%?±?39%) for all tested organs, except kidney, and recovery was constant over 5 log scales for all tested buffer systems. The LOD for Matrix-Lysis with subsequent plate count method (PCM) was as low as 1 CFU/5 g, while for qPCR based detection the LOD was 102 bacterial cell equivalents (BCE)/5 g for two buffer systems. Conclusions This tissue preparation is inexpensive and can be easily used for routine and analytical veterinary diagnostics. Inoculation studies or hazard assessments can profit from this tissue preparation method and it is anticipated that this study will be a valuable source for further research on tissue preparation strategies. PMID:24589061

2014-01-01

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 Monzón, A. N.; Pacheco Cano, R. D.; Balagurusamy, N.; Bideshi, Dennis K.; Salcedo-Hernández, Rubén

2012-01-01

82

Production of plantaricin NC8 by Lactobacillus plantarum NC8 is induced in the presence of different types of gram-positive bacteria  

Microsoft Academic Search

Lactobacillus plantarum NC8 was shown to produce plantaricin NC8 (PLNC8), a recently purified and genetically characterized inducible class IIb bacteriocin, only when it was co-cultured with other gram-positive bacteria. Among 82 strains belonging to the genera Bacillus, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Listeria, Pediococcus, Staphylococcus, and Streptococcus, 41 were shown to induce PLNC8 production in L. plantarum NC8. There was apparently

Antonio Maldonado; JoséLuis Ruiz-Barba; Rufino Jiménez-Díaz

2004-01-01

83

In situ probing of Gram-positive bacteria with high DNA G + C content using 23S rRNA-targeted oligonucleotides  

Microsoft Academic Search

235-rRNA-targeted oligonucleotide probes were designed for the phylogenetic group Gram-positive bacteria with high G + C content of DNA ' (GPBHGC). A sequence idiosyncrasy in two adjacent base pairs in the stem of helix 69 in domain IV of the 235 rRNA is present in all hitherto analysed strains of GPBHGC. An oligonucleotide probe targeted to this region hybridized only

Carsten Roller; Michael Wagner; Rudolf Amann; Wolfgang Ludwig; K.-H. Schleifer

1994-01-01

84

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

Microsoft Academic Search

Spo0A-phosphate is essential for the initiation of cellular differentiation and developmental pro- cesses in Gram-positive spore-forming bacteria. Here we combined comparative genomics with analyses of microarray expression profiles to iden- tify the Spo0A-phosphate regulon in Bacillus subti- lis. The consensus Spo0A-phosphate DNA-binding motif identified from the training set based on differ- ent computational algorithms is an 8 bp sequence, TTGTCGAA.

Jiajian Liu; Kai Tan; Gary D. Stormo

2003-01-01

85

Identification of the sigmaB regulon of Bacillus cereus and conservation of sigmaB-regulated genes in low-GC-content gram-positive bacteria  

Microsoft Academic Search

The alternative sigma factor B has an important role in the acquisition of stress resistance in many gram-positive bacteria, including the food-borne pathogen Bacillus cereus. Here, we describe the identification of the set of B-regulated genes in B. cereus by DNA microarray analysis of the transcriptome upon a mild heat shock. Twenty-four genes could be identified as being B dependent

Willem van Schaik; Menno van der Voort; Douwe Molenaar; Roy Moezelaar; Vos de W. M; Tjakko Abee

2007-01-01

86

Mechanism of Action of the Mannopeptimycins, a Novel Class of Glycopeptide Antibiotics Active against Vancomycin-Resistant Gram-Positive Bacteria  

Microsoft Academic Search

The naturally occurring mannopeptimycins (formerly AC98-1 through AC98-5) are a novel class of glyco- peptide antibiotics that are active against a wide variety of gram-positive bacteria. The structures of the mannopeptimycins suggested that they might act by targeting cell wall biosynthesis, similar to other known glycopeptide antibiotics; but the fact that the mannopeptimycins retain activity against vancomycin-resistant organisms suggested that

Alexey Ruzin; Guy Singh; Anatoly Severin; Youjun Yang; Russell G. Dushin; Alan G. Sutherland; Albert Minnick; Michael Greenstein; Michael K. May; David M. Shlaes; Patricia A. Bradford

2004-01-01

87

Functional synergy of ?-helical antimicrobial peptides and traditional antibiotics against Gram-negative and Gram-positive bacteria in vitro and in vivo.  

PubMed

In this study, the antimicrobial activities based on the synergistic effects of traditional antibiotics (imipenem, cefepime, levofloxacin hydrochloride and vancomycin) and antimicrobial peptides (AMPs; PL-5, PL-31, PL-32, PL-18, PL-29 and PL-26), alone or in combination, against three Gram-positive bacteria (Staphylococcus aureus, Streptococcus pneumoniae and Staphylococcus epidermidis) and three Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae) were investigated. In addition, the antimicrobial activity that was based on the synergistic effects of levofloxacin hydrochloride and PL-5 against Staphylococcus aureus in vivo was explored in a mouse infection model. Traditional antibiotics and AMPs showed significant synergistic effects on the antibacterial activities against the different Gram-positive and Gram-negative bacteria in vitro. A strong synergistic effect in the PL-5 and levofloxacin hydrochloride combination against Staphylococcus aureus was observed in the mouse infection model in vivo. The mechanism of synergistic action was due to the different targets of AMPs and traditional antibiotics. The combination of AMPs and traditional antibiotics can dramatically enhance antimicrobial activity and may help prevent or delay the emergence of antibiotic resistance. Thus, this combination therapy could be a promising approach to treat bacterial infections, particularly mixed infections and multi-antibiotic-resistant infections, in the clinics. PMID:25169965

Feng, Q; Huang, Y; Chen, M; Li, G; Chen, Y

2015-01-01

88

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

89

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

90

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

91

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

92

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

93

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

PubMed

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

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

2014-01-01

94

Efficient Photodynamic Therapy against Gram-Positive and Gram-Negative Bacteria Using THPTS, a Cationic Photosensitizer Excited by Infrared Wavelength  

PubMed Central

The worldwide rise in the rates of antibiotic resistance of bacteria underlines the need for alternative antibacterial agents. A promising approach to kill antibiotic-resistant bacteria uses light in combination with a photosensitizer to induce a phototoxic reaction. Concentrations of 1, 10 and 100µM of tetrahydroporphyrin-tetratosylat (THPTS) and different incubation times (30, 90 and 180min) were used to measure photodynamic efficiency against two Gram-positive strains of S.aureus (MSSA and MRSA), and two Gram-negative strains of E.coli and P.aeruginosa. We found that phototoxicity of the drug is independent of the antibiotic resistance pattern when incubated in PBS for the investigated strains. Also, an incubation with 100µM THPTS followed by illumination, yielded a 6lg (?99.999%) decrease in the viable numbers of all bacteria strains tested, indicating that the THPTS drug has a high degree of photodynamic inactivation. We then modulated incubation time, photosensitizer concentration and monitored the effect of serum on the THPTS activity. In doing so, we established the conditions to obtain the strongest bactericidal effect. Our results suggest that this new and highly pure synthetic compound should improve the efficiency of photodynamic therapy against multiresistant bacteria and has a significant potential for clinical applications in the treatment of nosocomial infections. PMID:20652031

Schastak, Stanislaw; Ziganshyna, Svitlana; Gitter, Burkhard; Wiedemann, Peter; Claudepierre, Thomas

2010-01-01

95

Studies on the O3-initiated disinfection from Gram-positive bacteria Bacillus subtilis in aquatic systems  

Microsoft Academic Search

The kinetics of inactivation of Gram-positive strain, Bacillus subtilis in aquatic systems was investigated as function ozone aeration duration under varied conditions. Oxygen flow was in situ enriched with ozone using ozoniser, with [O3] ranging from (0.3 – 9.8) × 10 moles per liter of oxygen. The inactivation kinetics of B. subtilis followed pseudo–first-order kinetics with respect to microbe, under

Favourite N. Zuma; S. B. Jonnalagadda

2010-01-01

96

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

97

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 Flávio Vasconcelos; Albuquerque, Maria Rose Jane R.; dos Santos, Hélcio Silva; Bandeira, Paulo Nogueira; Ávila, Fábio do Nascimento; da Silva, Bruno Rocha; Vasconcelos, Ariana Azevedo; Rabelo, Érica 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

98

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

PubMed

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

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

2013-05-01

99

A novel universal DNA labeling and amplification system for rapid microarray-based detection of 117 antibiotic resistance genes in Gram-positive bacteria.  

PubMed

A rapid and simple DNA labeling system has been developed for disposable microarrays and has been validated for the detection of 117 antibiotic resistance genes abundant in Gram-positive bacteria. The DNA was fragmented and amplified using phi-29 polymerase and random primers with linkers. Labeling and further amplification were then performed by classic PCR amplification using biotinylated primers specific for the linkers. The microarray developed by Perreten et al. (Perreten, V., Vorlet-Fawer, L., Slickers, P., Ehricht, R., Kuhnert, P., Frey, J., 2005. Microarray-based detection of 90 antibiotic resistance genes of gram-positive bacteria. J.Clin.Microbiol. 43, 2291-2302.) was improved by additional oligonucleotides. A total of 244 oligonucleotides (26 to 37 nucleotide length and with similar melting temperatures) were spotted on the microarray, including genes conferring resistance to clinically important antibiotic classes like ?-lactams, macrolides, aminoglycosides, glycopeptides and tetracyclines. Each antibiotic resistance gene is represented by at least 2 oligonucleotides designed from consensus sequences of gene families. The specificity of the oligonucleotides and the quality of the amplification and labeling were verified by analysis of a collection of 65 strains belonging to 24 species. Association between genotype and phenotype was verified for 6 antibiotics using 77 Staphylococcus strains belonging to different species and revealed 95% test specificity and a 93% predictive value of a positive test. The DNA labeling and amplification is independent of the species and of the target genes and could be used for different types of microarrays. This system has also the advantage to detect several genes within one bacterium at once, like in Staphylococcus aureus strain BM3318, in which up to 15 genes were detected. This new microarray-based detection system offers a large potential for applications in clinical diagnostic, basic research, food safety and surveillance programs for antimicrobial resistance. PMID:25451460

Strauss, Christian; Endimiani, Andrea; Perreten, Vincent

2015-01-01

100

Multicenter Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Gram-Positive Aerobic Bacteria  

PubMed Central

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting. PMID:23658261

Burnham, Carey-Ann D.; Bythrow, Maureen; Garner, Omai B.; Ginocchio, Christine C.; Jennemann, Rebecca; Lewinski, Michael A.; Manji, Ryhana; Mochon, A. Brian; Procop, Gary W.; Richter, Sandra S.; Sercia, Linda; Westblade, Lars F.; Ferraro, Mary Jane; Branda, John A.

2013-01-01

101

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

PubMed

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

[Studies on siderophore exchange properties between staphylococci and various species of gram-positive and gram-negative bacteria].  

PubMed

The ability of iron utilizing by means of staphylococcal siderophores by bacteria belonging to genera: Acinetobacter, Corynebacterium, Curtobacterium, Clavibacter, Bacillus and Mycobacterium was investigated. The staphylococcal donor strains (18 species) used in these experiments were characterized by the ability to utilize siderophores produced by various strains belonging to aforenamed genera. The utilization of staphylococcal siderophores was studied on agar media in which minimally effective concentrations of ethylenediaminedi-ortho-hydroxyphenylacetic acid (EDDA) were used to inhibit indicator strains. Test colonies (staphylococcal) were applied to the surface of the media to determine whether the indicator organisms could obtain the required iron for growth by utilizing chelators from the test colony. The growth inhibition by EDDA of most strains from the Acinetobacter rods and from the coryneform-organisms (plant pathogen) genera, and strains from the species: B. subtilis, M. phlei, M. smegmatis, M. fortuitum was reversed by staphylococcal siderophores. None of the staphylococcal strains investigated, had the ability to exchange siderophores with strains from the species: C. pseudodiphtheriticum, Corynebacterium ANF group, B. megaterium, M. vaccae, M. chitae and M. parafortuitum. PMID:10803251

Szarapi?ska-Kwaszewska, J; Mikucki, J

1999-01-01

103

Biocompatible Fe3O4 increases the efficacy of amoxicillin delivery against Gram-positive and Gram-negative bacteria.  

PubMed

This paper reports the synthesis and characterization of amoxicillin- functionalized magnetite nanostructures (Fe3O4@AMO), revealing and discussing several biomedical applications of these nanomaterials. Our results proved that 10 nm Fe3O4@AMO nanoparticles does not alter the normal cell cycle progression of cultured diploid cells, and an in vivo murine model confirms that the nanostructures disperse through the host body and tend to localize in particular sites and organs. The nanoparticles were found clustered especially in the lungs, kidneys and spleen, next to the blood vessels at this level, while being totally absent in the brain and liver, suggesting that they are circulated through the blood flow and have low toxicity. Fe3O4@AMO has the ability to be easily circulated through the body and optimizations may be done so these nanostructures cluster to a specific target region. Functionalized magnetite nanostructures proved a great antimicrobial effect, being active against both the Gram positive pathogen S. aureus and the Gram negative pathogen E. coli. The fabricated nanostructures significantly reduced the minimum inhibitory concentration (MIC) of the active drug. This result has a great practical relevance, since the functionalized nanostructures may be used for decreasing the therapeutic doses which usually manifest great severe side effects, when administrated in high doses. Fe3O4@AMO represents also a suitable approach for the development of new alternative strategies for improving the activity of therapeutic agents by targeted delivery and controlled release. PMID:24759068

Grumezescu, Alexandru Mihai; Gestal, Monica Cartelle; Holban, Alina Maria; Grumezescu, Valentina; Vasile, Bogdan Stefan; Mogoant?, Lauren?iu; Iordache, Florin; Bleotu, Coralia; Mogo?anu, George Dan

2014-01-01

104

Lactococcus lactis TrxD represents a subgroup of thioredoxins prevalent in Gram-positive bacteria containing WCXDC active site motifs.  

PubMed

Three protein disulfide reductases of the thioredoxin superfamily from the industrially important Gram-positive Lactococcus lactis (LlTrxA, LlTrxD and LlNrdH) are compared to the "classical" thioredoxin from Escherichia coli (EcTrx1). LlTrxA resembles EcTrx1 with a WCGPC active site motif and other key residues conserved. By contrast, LlTrxD is more distantly related and contains a WCGDC motif. Bioinformatics analysis suggests that LlTrxD represents a subgroup of thioredoxins from Gram-positive bacteria. LlNrdH is a glutaredoxin-like electron donor for ribonucleotide reductase class Ib. Based on protein-protein equilibria LlTrxA (E°'=-259mV) and LlNrdH (E°'=-238mV) show approximately 10mV higher standard state redox potentials than the corresponding E. coli homologues, while E°' of LlTrxD is -243mV, more similar to glutaredoxin than "classical" thioredoxin. EcTrx1 and LlTrxA have high capacity to reduce insulin disulfides and their exposed active site thiol is alkylated at a similar rate at pH 7.0. LlTrxD on the other hand, is alkylated by iodoacetamide at almost 100 fold higher rate and shows no activity towards insulin disulfides. LlTrxA, LlTrxD and LlNrdH are all efficiently reduced by NADPH dependent thioredoxin reductase (TrxR) from L. lactis and good cross-reactivity towards E. coli TrxR was observed with LlTrxD as the notable exception. PMID:25255970

Björnberg, Olof; Efler, Petr; Ebong, Epie Denis; Svensson, Birte; Hägglund, Per

2014-12-15

105

Prostaglandin H synthase isoenzyme distribution in the gingival tissue of patients with periodontitis: pronounced expression adjacent to gram-positive bacteria.  

PubMed

Prostaglandin (PGE(2)) is an inflammatory mediator that plays a critical role in the pathogenesis of periodontal disease. Prostaglandin H synthase (PGHS) a rate-limiting enzyme in PGE(2) biosynthesis exists as two separate isoforms (PGHS-1 and PGHS-2). We have previously demonstrated that both isoforms are generally present in the gingival tissue of periodontitis patients. This study explores in greater detail the variable distribution of each isoenzyme in both inflamed and non-inflamed gingival tissues of patients with periodontitis, and the relationship to adjacent bacteria. Although the positive staining for PGHS-1 was never as intense as for PGHS-2 in the same tissue specimen, either in inflamed or non-inflamed tissues, there was strong staining for both isoenzymes in the epithelium. The keratin layer did not stain. Non-keratinizing crevicular and junctional epithelium contained both isoenzymes through their full thickness in both inflamed and non-inflamed tissues. Pronounced staining of PGHS-2 was evident in the epithelia adjacent to Gram-positively stained organisms. In non-inflamed tissue, PGHS-1 and PGHS-2 were particularly evident in the spinous cell layer; however, fewer of the fibroblasts, endothelial cells, and resident mononuclear inflammatory cells stained positively for PGHS-1 as compared to PGHS-2, but this was less apparent in the inflamed tissues. The immunohistochemical staining patterns indicate that both crevicular and gingival epithelium are important sources of prostaglandin production in the gingival tissue of patients with periodontitis and that bacteria entrapped near to these sites may be important in promoting expression of inducible PGHS-2. PMID:17694359

McDonald, J S; Cavanaugh, P F; Pavelic, L J; Limardi, R J; Gluckman, J L; Pavelic, Z P

1997-01-01

106

In situ probing of gram-positive bacteria with high DNA G + C content using 23S rRNA-targeted oligonucleotides.  

PubMed

23S-rRNA-targeted oligonucleotide probes were designed for the phylogenetic group 'Gram-positive bacteria with high G + C content of DNA' (GPBHGC). A sequence idiosyncrasy in two adjacent base pairs in the stem of helix 69 in domain IV of the 23S rRNA is present in all hitherto analysed strains of GPBHGC. An oligonucleotide probe targeted to this region hybridized only with strains of GPBHGC and was successfully used for in situ monitoring of these cells in activated sludge. Another unique feature of the 23S rRNA molecules of GPBHGC is a large insertion in domain III. Fluorescent oligonucleotides targeted to the highly variable regions of the rRNA within the insertions of Corynebacterium glutamicum DSM 20300, Aureobacterium testaceum DSM 20166 and Brevibacterium sp. DSM 20165 hybridized specifically to their target strains, whereas probing with oligonucleotides complementary to the rRNA-coding strand of the 23S rDNA and to the spacer between 16S and 23S rRNA of C. glutamicum did not result in detectable fluorescence. This confirmed that the large 23S insertions are indeed present in 23S rRNAs of GPBHGC and provide potential target sites for highly specific nucleic acid probes. PMID:8000548

Roller, C; Wagner, M; Amann, R; Ludwig, W; Schleifer, K H

1994-10-01

107

Signatures of the ATP-binding pocket as a basis for structural classification of the serine/threonine protein kinases of gram-positive bacteria.  

PubMed

Eukaryotic-like serine/threonine protein kinases (ESTPKs) are widely spread throughout the bacterial genomes. These enzymes can be potential targets of new antibacterial drugs useful for the treatment of socially important diseases such as tuberculosis. In this study, ESTPKs of pathogenic, probiotic, and antibiotic-producing Gram-positive bacteria were classified according to the physicochemical properties of amino acid residues in the ATP-binding site of the enzyme. Nine residues were identified that line the surface of the adenine-binding pocket, and ESTPKs were classified based on these signatures. Twenty groups were discovered, five of them containing >10 representatives. The two most abundant groups contained >150 protein kinases that belong to the various branches of the phylogenetic tree, whereas certain groups are genus- or even species-specific. Homology modeling of the typical representatives of each group revealed that the classification is reliable, and the differences between the protein kinase ATP-binding pockets predicted based on their signatures are apparent in their structure. The classification is expected to be useful for the selection of targets for new anti-infective drugs. PMID:22275035

Zakharevich, Natalia V; Osolodkin, Dmitry I; Artamonova, Irena I; Palyulin, Vladimir A; Zefirov, Nikolay S; Danilenko, Valery N

2012-05-01

108

WhiA, a Protein of Unknown Function Conserved among Gram-Positive Bacteria, Is Essential for Sporulation in Streptomyces coelicolor A3(2)  

PubMed Central

The whiA sporulation gene of Streptomyces coelicolor A3(2), which plays a key role in switching aerial hyphae away from continued extension growth and toward sporulation septation, was cloned by complementation of whiA mutants. DNA sequencing of the wild-type allele and five whiA mutations verified that whiA is a gene encoding a protein with homologues in all gram-positive bacteria whose genome sequence is known, whether of high or low G+C content. No function has been attributed to any of these WhiA-like proteins. In most cases, as in S. coelicolor, the whiA-like gene is downstream of other conserved genes in an operon-like cluster. Phenotypic analysis of a constructed disruption mutant confirmed that whiA is essential for sporulation. whiA is transcribed from at least two promoters, the most downstream of which is located within the preceding gene and is strongly up-regulated when colonies are undergoing sporulation. The up-regulation depends on a functional whiA gene, suggesting positive autoregulation, although it is not known whether this is direct or indirect. Unlike the promoters of some other sporulation-regulatory genes, the whiA promoter does not depend on the sporulation-specific ? factor encoded by whiG. PMID:10986251

Aínsa, J. A.; Ryding, N. J.; Hartley, N.; Findlay, K. C.; Bruton, C. J.; Chater, K. F.

2000-01-01

109

Structural Basis for the De-N-acetylation of Poly-?-1,6-N-acetyl-d-glucosamine in Gram-positive Bacteria.  

PubMed

Exopolysaccharides are required for the development and integrity of biofilms produced by a wide variety of bacteria. In staphylococci, partial de-N-acetylation of the exopolysaccharide poly-?-1,6-N-acetyl-d-glucosamine (PNAG) by the extracellular protein IcaB is required for biofilm formation. To understand the molecular basis for PNAG de-N-acetylation, the structure of IcaB from Ammonifex degensii (IcaBAd) has been determined to 1.7 Å resolution. The structure of IcaBAd reveals a (?/?)7 barrel common to the family four carbohydrate esterases (CE4s) with the canonical motifs circularly permuted. The metal dependence of IcaBAd is similar to most CE4s showing the maximum rates of de-N-acetylation with Ni(2+), Co(2+), and Zn(2+). From docking studies with ?-1,6-GlcNAc oligomers and structural comparison to PgaB from Escherichia coli, the Gram-negative homologue of IcaB, we identify Arg-45, Tyr-67, and Trp-180 as key residues for PNAG binding during catalysis. The absence of these residues in PgaB provides a rationale for the requirement of a C-terminal domain for efficient deacetylation of PNAG in Gram-negative species. Mutational analysis of conserved active site residues suggests that IcaB uses an altered catalytic mechanism in comparison to other characterized CE4 members. Furthermore, we identified a conserved surface-exposed hydrophobic loop found only in Gram-positive homologues of IcaB. Our data suggest that this loop is required for membrane association and likely anchors IcaB to the membrane during polysaccharide biosynthesis. The work presented herein will help guide the design of IcaB inhibitors to combat biofilm formation by staphylococci. PMID:25359777

Little, Dustin J; Bamford, Natalie C; Pokrovskaya, Varvara; Robinson, Howard; Nitz, Mark; Howell, P Lynne

2014-12-26

110

3,5-Dioxopyrazolidines, Novel Inhibitors of UDP-N- Acetylenolpyruvylglucosamine Reductase (MurB) with Activity against Gram-Positive Bacteria  

PubMed Central

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

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

2006-01-01

111

Adsorption on stainless steel surfaces of biosurfactants produced by gram-negative and gram-positive bacteria: Consequence on the bioadhesive behavior of Listeria monocytogenes  

Microsoft Academic Search

The ability of adsorbed biosurfactants (Pf and Lb) obtained from gram-negative bacterium (Pseudomonas fluorescens) or gram-positive bacterium (Lactobacillus helveticus) to inhibit adhesion of four listerial strains to stainless steel was investigated. These metallic surfaces were characterized using the following complementary analytical techniques: contact-angle measurements (CAM), atomic force microscopy (AFM), polarization modulation-infrared reflection-adsorption spectroscopy (PM-IRRAS) and X-ray photoelectron spectroscopy (XPS). Contact-angles

Thierry Meylheuc; Christophe Methivier; Margareth Renault; Jean-Marie Herry; Claire-Marie Pradier; Marie Noëlle Bellon-Fontaine

2006-01-01

112

MiniUIB, a Novel Minitransposon-Based System for Stable Insertion of Foreign DNA into the Genomes of Gram-Negative and Gram-Positive Bacteria  

PubMed Central

Transposition of the insertion sequence (IS) ISPpu12 is actively induced after conjugative interaction. The transposase of this IS can act in trans on structures flanked by inverted repeats similar to those of the transposon. Based on that fact, an ISPpu12-based minitransposon, miniUIB, has been constructed in order to biotechnologically exploit the self-regulation of ISPpu12 and its increased activity after conjugative interaction. Mobilization of the miniUIB structure into the genome of Pseudomonas stutzeri AN10 after conjugative interaction was demonstrated. A single gene, i.e., the kanamycin resistance determinant, or large genetic structures of >12 kb, i.e., alkBFGHJKL and alkST operons of Pseudomonas putida TF4-1L (GPo1), have been easily integrated in P. stutzeri AN10 by an RP4-based delivery system. Therefore, the integration of the alk determinants by use of the miniUIB system has extended the biodegradation capabilities of this strain. Plasmid pJOC100, containing the transposase and regulator genes of ISPpu12 adjacent to the miniUIB structure, was constructed in order to extend the host range of this biotechnologically useful genetic tool to other model and real-world bacteria. The effectiveness of the system for random mutagenesis in a phylogenetic wide range of bacteria and for the insertion of novel functions has been demonstrated, even in successive steps. PMID:23275505

Christie-Oleza, Joseph Alexander; Brunet-Galmés, Isabel; Lalucat, Jorge; Nogales, Balbina

2013-01-01

113

?-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

114

Non-covalent association of protein and capsular polysaccharide on bacteria-sized latex beads as a model for polysaccharide-specific humoral immunity to intact Gram-positive extracellular bacteria1  

PubMed Central

Intact Streptococcus pneumoniae, expressing type 14 capsular polysaccharide (PPS14) and type III Streptococcus agalactiae containing a PPS14 core capsule identical to PPS14, exhibit non-covalent associations of PPS14 and bacterial protein, in contrast to soluble covalent conjugates of these respective antigens. Both bacteria and conjugates induce murine PPS14-specific IgG responses dependent on CD4+ T cells. Further, secondary immunization with conjugate and S. agalactiae, although not S. pneumoniae, results in a boosted response. However, in contrast to conjugate, PPS14-specific IgG responses to bacteria lack affinity maturation, utilize the 44.1-idiotype and are dependent on marginal zone B cells. To better understand the mechanism underlying this dichotomy we developed a minimal model of intact bacteria in which PPS14 and pneumococcal surface protein A (PspA) were stably attached to 1 ?m (bacteria-sized) latex beads, but not directly linked to each other, in contrast to PPS14-PspA conjugate. PPS14+[PspA] beads, similar to conjugate, induced in mice boosted PPS14-specific IgG secondary responses, dependent on T cells and ICOS-dependent costimulation, and in which priming could be achieved with PspA alone. In contrast to conjugate, but similar to intact bacteria, the primary PPS14-specific IgG response to PPS14+[PspA] beads peaked rapidly, with the secondary response highly enriched for the 44.1-idiotype and lacking affinity maturation. These results demonstrate that non-covalent association in a particle, of polysaccharide and protein, recapitulates essential immunologic characteristics of intact bacteria that are distinct from soluble covalent conjugates of these respective antigens. PMID:23926322

Colino, Jesus; Duke, Leah; Snapper, Clifford M.

2013-01-01

115

Pharmacodynamics of TD-1792, a Novel Glycopeptide-Cephalosporin Heterodimer Antibiotic Used against Gram-Positive Bacteria, in a Neutropenic Murine Thigh Model  

PubMed Central

TD-1792 is a novel glycopeptide-cephalosporin heterodimer investigational antibiotic that displays potent bactericidal effects against clinically relevant Gram-positive organisms in vitro. The present studies evaluated the in vivo pharmacokinetics (PK) and pharmacodynamics (PD) of TD-1792 in the neutropenic murine thigh infection animal model. TD-1792, dosed subcutaneously (SC), produced dose-dependent reduction in the thigh bacterial burden of several organisms, including methicillin-susceptible and -resistant strains of Staphylococcus aureus and Staphylococcus epidermidis (MSSA, MRSA, MSSE, MRSE, respectively), penicillin-susceptible strains of Streptococcus pneumoniae (PSSP), Streptococcus pyogenes, and vancomycin-intermediate-susceptible Staphylococcus aureus (VISA). In single-dose efficacy studies, the 1-log10 CFU kill effective dose (ED1-log kill) estimates for TD-1792 ranged from 0.049 to 2.55 mg/kg of body weight administered SC, and the bacterial burden was reduced by up to 3 log10 CFU/g from pretreatment values. Against S. aureus ATCC 33591 (MRSA), the total 24-h log10 stasis dose (EDstasis) and ED1-logkill doses for TD-1792 were 0.53 and 1.11 mg/kg/24 h, respectively, compared to 23.4 and 54.6 mg/kg/24 h for vancomycin, indicating that TD-1762 is 44- to 49-fold more potent than vancomycin. PK-PD analysis of data from single-dose and dose-fractionation studies for MRSA (ATCC 33591) demonstrated that the total-drug 24-h area under the concentration-time curve-to-MIC ratio (AUC/MIC ratio) was the best predictor of efficacy (r2 = 0.826) compared to total-drug maximum plasma concentration of drug-to-MIC ratio (Cmax/MIC ratio; r2 = 0.715) and percent time that the total-drug plasma drug concentration remains above the MIC (%Time>MIC; r2 = 0.749). The magnitudes of the total-drug AUC/MIC ratios associated with net bacterial stasis, a 1-log10 CFU reduction from baseline and near maximal effect, were 21.1, 37.2, and 51.8, respectively. PK-PD targets based on such data represent useful inputs for analyses to support dose selection decisions for clinical studies of patients. PMID:22155835

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

2012-01-01

116

Accentuate the (Gram) positive Victor Nizet  

E-print Network

EDITORIAL Accentuate the (Gram) positive Victor Nizet Received: 19 January 2010 /Accepted: 19 January 2010 # Springer-Verlag 2010 Keywords Gram-positive bacteria . Streptococcus . Special issue In the last two decades, Gram-positive bacteria have become the most common organisms associated

Nizet, Victor

117

Antimicrobial susceptibility of gram-negative and gram-positive bacteria collected from countries in Eastern Europe: results from the Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) 2004-2010.  

PubMed

The Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) commenced in 2004 to longitudinally monitor global changes in bacterial susceptibility to a suite of antimicrobial agents. The current study examined the activity of tigecycline and comparators against isolates collected across Eastern Europe between 2004 and 2010. Minimum inhibitory concentrations were determined using Clinical and Laboratory Standards Institute (CLSI) broth microdilution methodologies. Antimicrobial susceptibility was determined using CLSI interpretive criteria, and tigecycline susceptibility was established using European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints. This study included 10 295 Gram-negative and 4611 Gram-positive isolates from 42 centres. Extended-spectrum ?-lactamases (ESBLs) were reported among 15.3% of Escherichia coli and 39.3% of Klebsiella pneumoniae isolates; the highest rates were observed in Turkey (30.9%) and Bulgaria (53.8%), respectively. Imipenem-non-susceptible K. pneumoniae were identified only in Turkey. ESBL-positive E. coli were highly susceptible to imipenem (95.1%), meropenem (98.0%) and tigecycline (98.5%). Most antimicrobials showed poor activity against Acinetobacter baumannii and Pseudomonas aeruginosa. Vancomycin resistance was noted among 0.9% of Enterococcus faecalis and 11.7% of Enterococcus faecium isolates. High rates of susceptibility were reported for linezolid (99.7%) and tigecycline (100%) against E. faecium. One-quarter of Staphylococcus aureus isolates were meticillin-resistant S. aureus (MRSA), with the highest rate in Romania (51.5%); all MRSA were susceptible to linezolid, tigecycline and vancomycin. Antimicrobial resistance is high in much of Eastern Europe, with considerable variation seen among countries. Tigecycline and the carbapenems retain excellent activity against many pathogens from Eastern Europe; linezolid and vancomycin are active against most Gram-positive pathogens. PMID:23590898

Balode, Arta; Punda-Poli?, Volga; Dowzicky, Michael J

2013-06-01

118

In Vitro Antibacterial Activity of AZD0914, a New Spiropyrimidinetrione DNA Gyrase/Topoisomerase Inhibitor with Potent Activity against Gram-Positive, Fastidious Gram-Negative, and Atypical Bacteria.  

PubMed

AZD0914 is a new spiropyrimidinetrione bacterial DNA gyrase/topoisomerase inhibitor with potent in vitro antibacterial activity against key Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, and Streptococcus agalactiae), fastidious Gram-negative (Haemophilus influenzae and Neisseria gonorrhoeae), atypical (Legionella pneumophila), and anaerobic (Clostridium difficile) bacterial species, including isolates with known resistance to fluoroquinolones. AZD0914 works via inhibition of DNA biosynthesis and accumulation of double-strand cleavages; this mechanism of inhibition differs from those of other marketed antibacterial compounds. AZD0914 stabilizes and arrests the cleaved covalent complex of gyrase with double-strand broken DNA under permissive conditions and thus blocks religation of the double-strand cleaved DNA to form fused circular DNA. Whereas this mechanism is similar to that seen with fluoroquinolones, it is mechanistically distinct. AZD0914 exhibited low frequencies of spontaneous resistance in S. aureus, and if mutants were obtained, the mutations mapped to gyrB. Additionally, no cross-resistance was observed for AZD0914 against recent bacterial clinical isolates demonstrating resistance to fluoroquinolones or other drug classes, including macrolides, ?-lactams, glycopeptides, and oxazolidinones. AZD0914 was bactericidal in both minimum bactericidal concentration and in vitro time-kill studies. In in vitro checkerboard/synergy testing with 17 comparator antibacterials, only additivity/indifference was observed. The potent in vitro antibacterial activity (including activity against fluoroquinolone-resistant isolates), low frequency of resistance, lack of cross-resistance, and bactericidal activity of AZD0914 support its continued development. PMID:25385112

Huband, Michael D; Bradford, Patricia A; Otterson, Linda G; Basarab, Gregory S; Kutschke, Amy C; Giacobbe, Robert A; Patey, Sara A; Alm, Richard A; Johnstone, Michele R; Potter, Marie E; Miller, Paul F; Mueller, John P

2015-01-01

119

Transcriptional cross-regulation between Gram-negative and gram-positive bacteria, demonstrated using ArgP-argO of Escherichia coli and LysG-lysE of Corynebacterium glutamicum.  

PubMed

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 (ArgP(d)) variants that confer elevated Arg-independent argO expression, some (ArgP(d)-P274S, -S94L, and, to a lesser extent, -P108S) activated lysE expression in E. coli. However, the individual activating effects of LysG and ArgP(d) on lysE were mutually extinguished when both proteins were coexpressed in Arg- or His-supplemented cultures. In comparison with native ArgP, the active ArgP(d) 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; Gowrishankar, J

2012-10-01

120

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

121

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

122

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

123

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

124

QUORUM SENSING IN BACTERIA  

Microsoft Academic Search

? Abstract Quorum sensing is the regulation of gene expression in response to fluctuations in cell-population density. Quorum sensing bacteria produce and release chemical signal molecules called autoinducers that increase in concentration as a function of cell density. The detection of a minimal threshold stimulatory con- centration of an autoinducer leads to an alteration in gene expression. Gram-positive and Gram-negative

Melissa B. Miller; Bonnie L. Bassler

2001-01-01

125

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.

126

Effect of Azasteroids on Gram-Positive Bacteria  

PubMed Central

A group of nitrogen-containing steroids closely related in structure was screened for antibacterial activity, by use of Bacillus subtilis and Sarcina lutea as the test organisms. The most active compounds were cholesterol derivatives containing a tertiary or quaternary nitrogen in, or attached to, the A ring. Similar methyltestosterone or progesterone derivatives were inactive. All of the cholesterol derivatives that inhibited growth were surfactant, and, structurally, they would be classified as cationic detergents. Some of the inactive compounds were surfactant, but, structurally, they would be classified as nonionic detergents. Certain features of the antibacterial activity of one of the active steroids—ND 212 (4-dimethylaminoethyl-4-aza-5-cholesten-3-one methiodide)—were studied. Growth of a culture of B. subtilis containing 5 × 107 cells per milliliter was inhibited by 1 ?g/ml (1.7 × 10?6m) of ND 212. The amount of growth inhibition was directly related to both cell and steroid concentration. Loss of viability was rapid and irreversible. With B. subtilis, cell lysis was observed. With S. lutea grown in C14-glucose, ND 212 caused release into the media of up to 25% of the cellular radioactivity. Extensive leakage occurred before loss of viability was observed. At bacteriostatic azasteroid concentrations, there was little leakage. ND 212 was readily bound in large amounts to B. subtilis cells. Inactive azasteroids were bound poorly. C14-cholestanone was also bound, whereas C14-methyltestosterone and C14-progesterone were not bound in significant amounts. At least 50% of the bound C14-cholestanone was associated with the membrane fraction. PMID:4960181

Varricchio, Frederick; Doorenbos, Norman J.; Stevens, Audrey

1967-01-01

127

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,

128

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

129

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

130

Investigating lipoprotein biogenesis and function in the model Gram-positive bacterium Streptomyces coelicolormmi_7261 943..957  

E-print Network

Investigating lipoprotein biogenesis and function in the model Gram-positive bacterium Streptomyces the lipid- modified cysteine at the N-terminus of the mature lipoprotein. In all Gram-positive bacteria of the cyto- plasmic membrane. Here we identify lipoproteins in the model Gram-positive bacterium Streptomyces

Palmer, Tracy

131

Experimental fossilisation of the thermophilic Gram-positive bacterium Geobacillus SP7A: a long duration preservation study.  

E-print Network

Experimental fossilisation of the thermophilic Gram-positive bacterium Geobacillus SP7A: a long of fossilised microbes in recent and ancient rocks, we experimentally silicified a Gram-positive bacterium of Gram-positive bacteria was extremely rapid, thus allowing very good preservation of Geobacillus SP7A

Paris-Sud XI, Université de

132

Magnetotactic Bacteria  

Microsoft Academic Search

Bacteria with motility directed by the local geomagnetic field have been observed in marine sediments. These magnetotactic microorganisms possess flagella and contain novel structured particles, rich in iron, within intracytoplasmic membrane vesicles. Conceivably these particles impart to cells a magnetic moment. This could explain the observed migration of these organisms in fields as weak as 0.5 gauss.

Richard Blakemore

1975-01-01

133

Bacteria and Foodborne Illness  

MedlinePLUS

... Some parasites and chemicals also cause foodborne illnesses. Bacteria Bacteria are tiny organisms that can cause infections of the GI tract. Not all bacteria are harmful to humans. Some harmful bacteria may ...

134

Production of Value-added Products by Lactic Acid Bacteria  

Technology Transfer Automated Retrieval System (TEKTRAN)

Lactic acid bacteria (LAB) are a group of facultative anaerobic, catalase negative, nonmotile and nonsporeforming–Gram positive bacteria. Most LAB utilize high energy C sources including monomer sugars to produce energy to maintain cellular structure and function. This anaerobic fermentation proce...

135

Carbon Flow of Heliobacteria Is Related More to Clostridia than to the Green Sulfur Bacteria*S  

E-print Network

are a relatively newly discovered group of anaerobic photosynthetic bacteria. All of the cultured heliobac- teria require organic carbon for anoxygenic growth, and several of the species can fix nitrogen (1, 2). Heliobacteria are the only cultured Gram-positive photosynthetic bacteria and are phylo- genetically related

Alvarez-Cohen, Lisa

136

Management of Gram-Positive Bacterial Disease: Staphylococcus aureus , Streptococcal, Pneumococcal and Enterococcal Infections  

Microsoft Academic Search

\\u000a Gram-positive bacteria are a diverse group of organisms that are a major source of morbidity and mortality in patients with\\u000a cancer. The increasing use of long-term indwelling central catheters and cytotoxic chemotherapies has contributed to the emergence\\u000a of Gram-positive bacteria as the leading cause of bacteremia in cancer patients. These organisms are also among the foremost\\u000a causes of pneumonia, skin

Samuel Shelburne; Daniel M. Musher

137

Back To Bacteria.  

ERIC Educational Resources Information Center

Explores new research about bacteria. Discusses bacterial genomes, archaea, unusual environments, evolution, pathogens, bacterial movement, biofilms, bacteria in the body, and a bacterial obsession. Contains 29 references. (JRH)

Flannery, Maura C.

1997-01-01

138

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

139

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

140

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, Richard L. (Clinton, TN)

1995-01-01

141

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

142

Virulence Plasmids of Nonsporulating Gram-Positive Pathogens  

PubMed Central

SUMMARY Gram-positive bacteria are leading causes of many types of human infection, including pneumonia, skin and nasopharyngeal infections, as well as urinary tract and surgical wound infections among hospitalized patients. These infections have become particularly problematic because many of the species causing them have become highly resistant to antibiotics. The role of mobile genetic elements, such as plasmids, in the dissemination of antibiotic resistance among Gram-positive bacteria has been well studied; less well understood is the role of mobile elements in the evolution and spread of virulence traits among these pathogens. While these organisms are leading agents of infection, they are also prominent members of the human commensal ecology. It appears that these bacteria are able to take advantage of the intimate association between host and commensal, via virulence traits that exacerbate infection and cause disease. However, evolution into an obligate pathogen has not occurred, presumably because it would lead to rejection of pathogenic organisms from the host ecology. Instead, in organisms that exist as both commensal and pathogen, selection has favored the development of mechanisms for variability. As a result, many virulence traits are localized on mobile genetic elements, such as virulence plasmids and pathogenicity islands. Virulence traits may occur within a minority of isolates of a given species, but these minority populations have nonetheless emerged as a leading problem in infectious disease. This chapter reviews virulence plasmids in nonsporulating Gram-positive bacteria, and examines their contribution to disease pathogenesis. PMID:25544937

Van Tyne, Daria; Gilmore, Michael S.

2014-01-01

143

A Myeloid Hypoxia-inducible Factor 1?-Krüppel-like Factor 2 Pathway Regulates Gram-positive Endotoxin-mediated Sepsis*  

PubMed Central

Although Gram-positive infections account for the majority of cases of sepsis, the molecular mechanisms underlying their effects remains poorly understood. We investigated how cell wall components of Gram-positive bacteria contribute to the development of sepsis. Experimental observations derived from cultured primary macrophages and the cell line indicate that Gram-positive bacterial endotoxins induce hypoxia-inducible factor 1? (HIF-1?) mRNA and protein expression. Inoculation of live or heat-inactivated Gram-positive bacteria with macrophages induced HIF-1 transcriptional activity in macrophages. Concordant with these results, myeloid deficiency of HIF-1? attenuated Gram-positive bacterial endotoxin-induced cellular motility and proinflammatory gene expression in macrophages. Conversely, Gram-positive bacteria and their endotoxins reduced expression of the myeloid anti-inflammatory transcription factor Krüppel-like transcription factor 2 (KLF2). Sustained expression of KLF2 reduced and deficiency of KLF2 enhanced Gram-positive endotoxins induced HIF-1? mRNA and protein expression in macrophages. More importantly, KLF2 attenuated Gram-positive endotoxins induced cellular motility and proinflammatory gene expression in myeloid cells. Consistent with these results, mice deficient in myeloid HIF-1? were protected from Gram-positive endotoxin-induced sepsis mortality and clinical symptomatology. By contrast, myeloid KLF2-deficient mice were susceptible to Gram-positive sepsis induced mortality and clinical symptoms. Collectively, these observations identify HIF-1? and KLF2 as critical regulators of Gram-positive endotoxin-mediated sepsis. PMID:22110137

Mahabeleshwar, Ganapati H.; Qureshi, Muhammad Awais; Takami, Yoichi; Sharma, Nikunj; Lingrel, Jerry B.; Jain, Mukesh K.

2012-01-01

144

Bacteria Inactivation During Lithotripsy  

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

145

Bleach vs. Bacteria  

MedlinePLUS

... Articles | Inside Life Science Home Page Bleach vs. Bacteria By Sharon Reynolds Posted April 2, 2014 Your ... hypochlorous acid to help kill invading microbes, including bacteria. Researchers funded by the National Institutes of Health ...

146

Communication in Bacteria  

Microsoft Academic Search

Bacteria communicate with one another using chemical signal molecules. As in higher organisms, the information supplied by these molecules is critical for synchronizing the activities of large groups of cells. In bacteria, chemical communication involves producing, re- leasing, detecting, and responding to small hormone-like molecules termed autoinducers. This process, termed quorum sensing, allows bacteria to monitor the environment for other

Christopher M. Waters; Bonnie L. Bassler

147

CHAPTER IV-2 BACTERIA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Entomopathogenic bacteria provide an alternative to chemical pesticides used in insect control programs. Today, the principal microbial insecticides utilize spore forming bacteria or toxins produced by these bacteria as their active ingredients, either in formulations or by incorporation of toxin g...

148

Phylogenetic analysis on the soil bacteria distributed in karst forest  

PubMed Central

Phylogenetic composition of bacterial community in soil of a karst forest was analyzed by culture-independent molecular approach. The bacterial 16S rRNA gene was amplified directly from soil DNA and cloned to generate a library. After screening the clone library by RFLP, 16S rRNA genes of representative clones were sequenced and the bacterial community was analyzed phylogenetically. The 16S rRNA gene inserts of 190 clones randomly selected were analyzed by RFLP and generated 126 different RFLP types. After sequencing, 126 non-chimeric sequences were obtained, generating 113 phylotypes. Phylogenetic analysis revealed that the bacteria distributed in soil of the karst forest included the members assigning into Proteobacteria, Acidobacteria, Planctomycetes, Chloroflexi (Green nonsulfur bacteria), Bacteroidetes, Verrucomicrobia, Nitrospirae, Actinobacteria (High G+C Gram-positive bacteria), Firmicutes (Low G+C Gram-positive bacteria) and candidate divisions (including the SPAM and GN08). PMID:24031430

Zhou, JunPei; Huang, Ying; Mo, MingHe

2009-01-01

149

Bacteria Are Everywhere!  

NSDL National Science Digital Library

Students are introduced to the concept of engineering biological organisms and studying their growth to be able to identify periods of fast and slow growth. They learn that bacteria are found everywhere, including on the surfaces of our hands. Student groups study three different conditions under which bacteria are found and compare the growth of the individual bacteria from each source. In addition to monitoring the quantity of bacteria from differ conditions, they record the growth of bacteria over time, which is an excellent tool to study binary fission and the reproduction of unicellular organisms.

AMPS GK-12 Program,

150

Biosorption of heavy metals by bacteria isolated from activated sludge  

Microsoft Academic Search

Twelve aerobic bacteria from activated sludge were isolated and identified. These included both Gram-positive (e.g., Bacillus) and Gram-negative (e.g., Pseudomonas) bacteria. The biosorption capacity of these strains for three different heavy metals (copper, nickel, and lead) was determined\\u000a at pH 5.0 and initial metal concentration of 100 mg\\/L. Among these 12 isolates, Pseudomonas pseudoalcaligenes was selected for further investigation owing

Wa C. Leung; Hong Chua; Waihung Lo

2001-01-01

151

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... Star Healthy Streams * ? Environmental Management of Grazing Lands * *TWRI-managed projects More information on the initiative is available at www.tsswcb.state.tx.us/managementprogram/ initiatives/bacteria. Bacteria Projects Across the State...

Wythe, Kathy

2007-01-01

152

Introduction to Bacteria  

NSDL National Science Digital Library

This science site has students research how bacteria move, where they live, and how they reproduce; learn how bacteria can be helpful or harmful; and create a design illustrating what they have learned about bacteria. Included in the lesson plan are the objectives, needed materials and Web sites, procedures, discussion questions, evaluation, extensions, suggested reading, and vocabulary. Teachers can link to Teaching Tools to create custom worksheets, puzzles, and quizzes. A printable version of the lesson plan can be downloaded. The video Bacteria, Viruses and Allergies can be purchased and comprehension questions and answers can be downloaded.

Discoveryschool.com; Fenichel, Marilyn

2007-12-12

153

High efficiency recombineering in lactic acid bacteria  

PubMed Central

The ability to efficiently generate targeted point mutations in the chromosome without the need for antibiotics, or other means of selection, is a powerful strategy for genome engineering. Although oligonucleotide-mediated recombineering (ssDNA recombineering) has been utilized in Escherichia coli for over a decade, the successful adaptation of ssDNA recombineering to Gram-positive bacteria has not been reported. Here we describe the development and application of ssDNA recombineering in lactic acid bacteria. Mutations were incorporated in the chromosome of Lactobacillus reuteri and Lactococcus lactis without selection at frequencies ranging between 0.4% and 19%. Whole genome sequence analysis showed that ssDNA recombineering is specific and not hypermutagenic. To highlight the utility of ssDNA recombineering we reduced the intrinsic vancomymycin resistance of L. reuteri >100-fold. By creating a single amino acid change in the d-Ala-d-Ala ligase enzyme we reduced the minimum inhibitory concentration for vancomycin from >256 to 1.5?µg/ml, well below the clinically relevant minimum inhibitory concentration. Recombineering thus allows high efficiency mutagenesis in lactobacilli and lactococci, and may be used to further enhance beneficial properties and safety of strains used in medicine and industry. We expect that this work will serve as a blueprint for the adaptation of ssDNA recombineering to other Gram-positive bacteria. PMID:22328729

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

2012-01-01

154

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

PubMed Central

We have cloned homologs of the Pseudomonas putida GPo1 alkane hydroxylase from Pseudomonas aeruginosa PAO1, Pseudomonas fluorescens CHA0, Alcanivorax borkumensis AP1, Mycobacterium tuberculosis H37Rv, and Prauserella rugosa NRRL B-2295. Sequence comparisons show that the level of protein sequence identity between the homologs is as low as 35%, and that the Pseudomonas alkane hydroxylases are as distantly related to each other as to the remaining alkane hydroxylases. Based on the observation that rubredoxin, an electron transfer component of the GPo1 alkane hydroxylase system, can be replaced by rubredoxins from other alkane hydroxylase systems, we have developed three recombinant host strains for the functional analysis of the novel alkane hydroxylase genes. Two hosts, Escherichia coli GEc137 and P. putida GPo12, were equipped with pGEc47?B, which encodes all proteins necessary for growth on medium-chain-length alkanes (C6 to C12), except a functional alkane hydroxylase. The third host was an alkB knockout derivative of P. fluorescens CHA0, which is no longer able to grow on C12 to C16 alkanes. All alkane hydroxylase homologs, except the Acinetobacter sp. ADP1 AlkM, allowed at least one of the three hosts to grow on n-alkanes. PMID:11872725

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

2002-01-01

155

The RNPP family of quorum-sensing proteins in Gram-positive bacteria  

Microsoft Academic Search

Quorum sensing is one of several mechanisms that bacterial cells use to interact with each other and coordinate certain physiological\\u000a processes in response to cell density. This mechanism is mediated by extracellular signaling molecules; once a critical threshold\\u000a concentration has been reached, a target sensor kinase or response regulator is activated (or repressed), facilitating the\\u000a expression of quorum sensing-dependent genes.

Jorge Rocha-Estrada; Angel E. Aceves-Diez; Gabriel Guarneros; Mayra de la Torre

2010-01-01

156

Novel polycarboxylate porphyrins: Synthesis, characterization, photophysical properties and preliminary antimicrobial study against Gram-positive bacteria.  

PubMed

We describe the synthesis, characterization and photophysical properties of two new polycarboxylic photosensitizers. Owing to their structural design, these two compounds show water solubilities larger than natural carboxylic photosensitizers (e.g., protoporphyrin IX, hematoporphyrin, etc.) and also good singlet oxygen quantum yields. These compounds were tested as photo-antimicrobial agents against Staphylococcus aureus and Bacillus cereus strains. Results reveal that their photocytotoxicities are strongly dependent on their amphiphilic character and more precisely the number and position of the carboxylic acid and mesityl substituents. PMID:25475206

Jiblaoui, Ahmad; Leroy-Lhez, Stéphanie; Ouk, Tan-Sothea; Grenier, Karine; Sol, Vincent

2015-01-15

157

The effect of nutrient media water purity on LIBS based identification of bacteria  

Technology Transfer Automated Retrieval System (TEKTRAN)

Single pulse laser induced breakdown spectroscopy (LIBS) is used as the basis for discrimination between 3 genera of Gram-negative bacteria and 2 genera of gram-positive bacteria representing pathogenic threats commonly found in poultry processing rinse waters. Because LIBS-based discrimination reli...

158

Nonstaining (KOH) method for determination of gram reactions of marine bacteria.  

PubMed

A rapid nonstaining (KOH) method for the determination of the Gram reactions of bacteria is described, and its application to marine isolates is discussed. All gram-positive and gram-negative results obtained by Gram staining were confirmed by the KOH method. Gram-variable bacteria produced equivocal results. PMID:6184019

Buck, J D

1982-10-01

159

Application of molecular methods for the classification and identification of lactic acid bacteria  

Microsoft Academic Search

Phylogenetic analysis has revealed that the typical lactic acid bacteria (LAB) belong to the Gram-positive bacteria with a low guanine plus cytosine DNA content. The genera Lactobacillus, Leuconostoc and Pediococcus can be traditionally differentiated on the basis of morphological and physiological properties but phylogentically they are intermixed. The former genus Streptococcus has been split up into the four genera Enterococcus,

Karl-Heinz Schleifer; Mathias Ehrmann; Claudia Beimfohr; Elke Brockmann; Wolfgang Ludwig; Rudolf Amann

1995-01-01

160

Bacteria turn tiny gears  

SciTech Connect

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

None

2009-01-01

161

Inactivation of biofilm bacteria.  

PubMed Central

The current project was developed to examine inactivation of biofilm bacteria and to characterize the interaction of biocides with pipe surfaces. Unattached bacteria were quite susceptible to the variety of disinfectants tested. Viable bacterial counts were reduced 99% by exposure to 0.08 mg of hypochlorous acid (pH 7.0) per liter (1 to 2 degrees C) for 1 min. For monochloramine, 94 mg/liter was required to kill 99% of the bacteria within 1 min. These results were consistent with those found by other investigators. Biofilm bacteria grown on the surfaces of granular activated carbon particles, metal coupons, or glass microscope slides were 150 to more than 3,000 times more resistant to hypochlorous acid (free chlorine, pH 7.0) than were unattached cells. In contrast, resistance of biofilm bacteria to monochloramine disinfection ranged from 2- to 100-fold more than that of unattached cells. The results suggested that, relative to inactivation of unattached bacteria, monochloramine was better able to penetrate and kill biofilm bacteria than free chlorine. For free chlorine, the data indicated that transport of the disinfectant into the biofilm was a major rate-limiting factor. Because of this phenomenon, increasing the level of free chlorine did not increase disinfection efficiency. Experiments where equal weights of disinfectants were used suggested that the greater penetrating power of monochloramine compensated for its limited disinfection activity. These studies showed that monochloramine was as effective as free chlorine for inactivation of biofilm bacteria. The research provides important insights into strategies for control of biofilm bacteria. Images PMID:2849380

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

1988-01-01

162

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

163

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

164

Inactivation of Gram-positive biofilms by low-temperature plasma jet at atmospheric pressure  

Microsoft Academic Search

This work is devoted to the evaluation of the efficiency of a new low-temperature plasma jet driven in ambient air by a dc-corona discharge to inactivate adherent cells and biofilms of Gram-positive bacteria. The selected microorganisms were lactic acid bacteria, a Weissella confusa strain which has the particularity to excrete a polysaccharide polymer (dextran) when sucrose is present. Both adherent

F Marchal; H Robert; N Merbahi; C Fontagné-Faucher; M Yousfi; C E Romain; O Eichwald; C Rondel; B Gabriel

2012-01-01

165

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

166

Bacteria: More Than Pathogens  

NSDL National Science Digital Library

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

Wassenaar, Trudy M.

2008-04-01

167

Aerobic Anoxygenic Phototrophic Bacteria  

PubMed Central

The aerobic anoxygenic phototrophic bacteria are a relatively recently discovered bacterial group. Although taxonomically and phylogenetically heterogeneous, these bacteria share the following distinguishing features: the presence of bacteriochlorophyll a incorporated into reaction center and light-harvesting complexes, low levels of the photosynthetic unit in cells, an abundance of carotenoids, a strong inhibition by light of bacteriochlorophyll synthesis, and the inability to grow photosynthetically under anaerobic conditions. Aerobic anoxygenic phototrophic bacteria are classified in two marine (Erythrobacter and Roseobacter) and six freshwater (Acidiphilium, Erythromicrobium, Erythromonas, Porphyrobacter, Roseococcus, and Sandaracinobacter) genera, which phylogenetically belong to the ?-1, ?-3, and ?-4 subclasses of the class Proteobacteria. Despite this phylogenetic information, the evolution and ancestry of their photosynthetic properties are unclear. We discuss several current proposals for the evolutionary origin of aerobic phototrophic bacteria. The closest phylogenetic relatives of aerobic phototrophic bacteria include facultatively anaerobic purple nonsulfur phototrophic bacteria. Since these two bacterial groups share many properties, yet have significant differences, we compare and contrast their physiology, with an emphasis on morphology and photosynthetic and other metabolic processes. PMID:9729607

Yurkov, Vladimir V.; Beatty, J. Thomas

1998-01-01

168

Lipopolysaccharides in diazotrophic bacteria.  

PubMed

Biological nitrogen fixation (BNF) is a process in which the atmospheric nitrogen (N2) is transformed into ammonia (NH3) by a select group of nitrogen-fixing organisms, or diazotrophic bacteria. In order to furnish the biologically useful nitrogen to plants, these bacteria must be in constant molecular communication with their host plants. Some of these molecular plant-microbe interactions are very specific, resulting in a symbiotic relationship between the diazotroph and the host. Others are found between associative diazotrophs and plants, resulting in plant infection and colonization of internal tissues. Independent of the type of ecological interaction, glycans, and glycoconjugates produced by these bacteria play an important role in the molecular communication prior and during colonization. Even though exopolysaccharides (EPS) and lipochitooligosaccharides (LCO) produced by diazotrophic bacteria and released onto the environment have their importance in the microbe-plant interaction, it is the lipopolysaccharides (LPS), anchored on the external membrane of these bacteria, that mediates the direct contact of the diazotroph with the host cells. These molecules are extremely variable among the several species of nitrogen fixing-bacteria, and there are evidences of the mechanisms of infection being closely related to their structure. PMID:25232535

Serrato, Rodrigo V

2014-01-01

169

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

170

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

171

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

172

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

173

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

PubMed Central

Gram-positive pathogens are a significant cause of morbidity and mortality in both community and health care settings. Glycopeptides have traditionally been the antibiotics of choice for multiresistant Gram-positive pathogens but there are problems with their use, including the emergence of glycopeptide-resistant strains, tissue penetration, and achieving and monitoring adequate serum levels. Newer antibiotics such as linezolid, a synthetic oxazolidinone, are available for the treatment of resistant Gram-positive bacteria. Linezolid is active against a wide range of Gram-positive bacteria and has been generally available for the treatment of Gram-positive infections since 2000. There are potential problems with linezolid use, including its bacteriostatic action and the relatively high incidence of reported adverse effects, particularly with long-term use. Long-term use may also be complicated by the development of resistance. However, linezolid has been shown to be clinically useful in the treatment of several serious infections where traditionally bacteriocidal agents have been required and many of its adverse effects are reversible on cessation. It has also been shown to be a cost-effective treatment option in several studies, with its high oral bioavailability allowing an early change from intravenous to oral formulations with consequent earlier patient discharge and lower inpatient costs. PMID:22787406

Ager, Sally; Gould, Kate

2012-01-01

174

Biological Characterization of Novel Inhibitors of the Gram-Positive DNA Polymerase IIIC Enzyme  

PubMed Central

Novel N-3-alkylated 6-anilinouracils have been identified as potent and selective inhibitors of bacterial DNA polymerase IIIC, the enzyme essential for the replication of chromosomal DNA in gram-positive bacteria. A nonradioactive assay measuring the enzymatic activity of the DNA polymerase IIIC in gram-positive bacteria has been assembled. The 6-anilinouracils described inhibited the polymerase IIIC enzyme at concentrations in the nanomolar range in this assay and displayed good in vitro activity (according to their MICs) against staphylococci, streptococci, and enterococci. The MICs of the most potent derivatives were about 4 ?g/ml for this panel of bacteria. The 50% effective dose of the best compound (6-[(3-ethyl-4-methylphenyl)amino]-3-{[1-(isoxazol-5-ylcarbonyl)piperidin-4-yl]methyl}uracil) was 10 mg/kg of body weight after intravenous application in a staphylococcal sepsis model in mice, from which in vivo pharmacokinetic data were also acquired. PMID:15728893

Kuhl, Alexander; Svenstrup, Niels; Ladel, Christoph; Otteneder, Michael; Binas, Annegret; Schiffer, Guido; Brands, Michael; Lampe, Thomas; Ziegelbauer, Karl; Rübsamen-Waigmann, Helga; Haebich, Dieter; Ehlert, Kerstin

2005-01-01

175

Biofilm bacteria: formation and comparative susceptibility to antibiotics  

PubMed Central

The Calgary Biofilm Device (CBD) was used to form bacterial biofilms of selected veterinary gram-negative and gram-positive pathogenic bacteria from cattle, sheep, pigs, chicken, and turkeys. The minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) of ampicillin, ceftiofur, cloxacillin, oxytetracycline, penicillin G, streptomycin, tetracycline, enrofloxacin, erythromycin, gentamicin, tilmicosin, and trimethoprim-sulfadoxine for gram-positive and -negative bacteria were determined. Bacterial biofilms were readily formed on the CBD under selected conditions. The biofilms consisted of microcolonies encased in extracellular polysaccharide material. Biofilms composed of Arcanobacterium (Actinomyces) pyogenes, Staphylococcus aureus, Staphylococcus hyicus, Streptococcus agalactiae, Corynebacterium renale, or Corynebacterium pseudotuberculosis were not killed by the antibiotics tested but as planktonic bacteria they were sensitive at low concentrations. Biofilm and planktonic Streptococcus dysgalactiae and Streptococcus suis were sensitive to penicillin, ceftiofur, cloxacillin, ampicillin, and oxytetracycline. Planktonic Escherichia coli were sensitive to enrofloxacin, gentamicin, oxytetracycline and trimethoprim/ sulfadoxine. Enrofloxacin and gentamicin were the most effective antibiotics against E. coli growing as a biofilm. Salmonella spp. and Pseudomonas aeruginosa isolates growing as planktonic populations were sensitive to enrofloxacin, gentamicin, ampicillin, oxytetracycline, and trimethoprim/sulfadoxine, but as a biofilm, these bacteria were only sensitive to enrofloxacin. Planktonic and biofilm Pasteurella multocida and Mannheimia haemolytica had similar antibiotic sensitivity profiles and were sensitive to most of the antibiotics tested. The CBD provides a valuable new technology that can be used to select antibiotics that are able to kill bacteria growing as biofilms. PMID:11989739

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

2002-01-01

176

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

177

bacteria driven polymerization  

E-print Network

12/20/2007 1 Motion of bacteria driven by actin polymerization forces Michael C. DeSantis Physics.B. Alberts) Examples of other intracellular pathogens propelled by actoclampins (actin filament (+)-end by actin polymerization. Cell signaling and its influence by actin polymerization transitions

Wang, Yan Mei

178

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

179

Invasion of dentinal tubules by oral bacteria.  

PubMed

Bacterial invasion of dentinal tubules commonly occurs when dentin is exposed following a breach in the integrity of the overlying enamel or cementum. Bacterial products diffuse through the dentinal tubule toward the pulp and evoke inflammatory changes in the pulpo-dentin complex. These may eliminate the bacterial insult and block the route of infection. Unchecked, invasion results in pulpitis and pulp necrosis, infection of the root canal system, and periapical disease. While several hundred bacterial species are known to inhabit the oral cavity, a relatively small and select group of bacteria is involved in the invasion of dentinal tubules and subsequent infection of the root canal space. Gram-positive organisms dominate the tubule microflora in both carious and non-carious dentin. The relatively high numbers of obligate anaerobes present-such as Eubacterium spp., Propionibacterium spp., Bifidobacterium spp., Peptostreptococcus micros, and Veillonella spp.-suggest that the environment favors growth of these bacteria. Gram-negative obligate anaerobic rods, e.g., Porphyromonas spp., are less frequently recovered. Streptococci are among the most commonly identified bacteria that invade dentin. Recent evidence suggests that streptococci may recognize components present within dentinal tubules, such as collagen type I, which stimulate bacterial adhesion and intra-tubular growth. Specific interactions of other oral bacteria with invading streptococci may then facilitate the invasion of dentin by select bacterial groupings. An understanding the mechanisms involved in dentinal tubule invasion by bacteria should allow for the development of new control strategies, such as inhibitory compounds incorporated into oral health care products or dental materials, which would assist in the practice of endodontics. PMID:12097359

Love, R M; Jenkinson, H F

2002-01-01

180

Multitasking SecB chaperones in bacteria  

PubMed Central

Protein export in bacteria is facilitated by the canonical SecB chaperone, which binds to unfolded precursor proteins, maintains them in a translocation competent state and specifically cooperates with the translocase motor SecA to ensure their proper targeting to the Sec translocon at the cytoplasmic membrane. Besides its key contribution to the Sec pathway, SecB chaperone tasking is critical for the secretion of the Sec-independent heme-binding protein HasA and actively contributes to the cellular network of chaperones that control general proteostasis in Escherichia coli, as judged by the significant interplay found between SecB and the trigger factor, DnaK and GroEL chaperones. Although SecB is mainly a proteobacterial chaperone associated with the presence of an outer membrane and outer membrane proteins, secB-like genes are also found in Gram-positive bacteria as well as in certain phages and plasmids, thus suggesting alternative functions. In addition, a SecB-like protein is also present in the major human pathogen Mycobacterium tuberculosis where it specifically controls a stress-responsive toxin–antitoxin system. This review focuses on such very diverse chaperone functions of SecB, both in E. coli and in other unrelated bacteria. PMID:25538690

Sala, Ambre; Bordes, Patricia; Genevaux, Pierre

2014-01-01

181

Detection of bacteria with bioluminescent reporter bacteriophage.  

PubMed

Bacteriophages are viruses that exclusively infect bacteria. They are ideally suited for the development of highly specific diagnostic assay systems. Bioluminescent reporter bacteriophages are designed and constructed by integration of a luciferase gene in the virus genome. Relying on the host specificity of the phage, the system enables rapid, sensitive, and specific detection of bacterial pathogens. A bioluminescent reporter phage assay is superior to any other molecular detection method, because gene expression and light emission are dependent on an active metabolism of the bacterial cell, and only viable cells will yield a signal. In this chapter we introduce the concept of creating reporter phages, discuss their advantages and disadvantages, and illustrate the advances made in developing such systems for different Gram-negative and Gram-positive pathogens. The application of bioluminescent reporter phages for the detection of foodborne pathogens is emphasized. PMID:25084997

Klumpp, Jochen; Loessner, Martin J

2014-01-01

182

News and Research Good Bacteria  

E-print Network

News and Research Good Bacteria Part 2 Article 13 Click here for Probiotics Basics Cooperation Is A No-brainer For Symbiotic Bacteria 9-4-2003 Humans may learn cooperation in kindergarten, but what about bacteria, whose behavior is preprogrammed by their DNA? Some legume plants, which rely

West, Stuart

183

Antimicrobial Action of Some Citrus Fruit Oils on Selected Food-Borne Bacteria  

PubMed Central

The antimicrobial properties of essential oils, terpineol, and orange oil, in particular, varied according to the type of bacteria tested. Terpineol and other terpeneless fractions of citrus oils appeared to have greater inhibitory effect on food-borne bacteria than the other citrus oils or derivatives. Gram-positive bacteria were, in general, more sensitive to essential oils than gram-negative bacteria. Terpineol extended the shelf life of commercially pasteurized skim milk, low-fat milk, and whole milk for more than 56 days at 4 C. Orange oil extended the shelf life of skim milk and low-fat milk for the same period. PMID:4905947

Dabbah, Roger; Edwards, V. M.; Moats, W. A.

1970-01-01

184

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

185

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

186

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.

187

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

188

Glacial lake hides bacteria  

NSDL National Science Digital Library

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

Peplow, Mark; Online, Bioed

189

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

PubMed Central

In the present study, the antibacterial effect of 20 lactic acid bacteria isolates from a traditional cheese was investigated. 6 isolates showed antibacterial effect against Gram positive bacteria. Streptococcus thermophilus T2 strain showed the wide inhibitory spectrum against the Gram positive bacteria. Growth and bacteriocin production profiles showed that the maximal bacteriocin production, by S. thermophilus T2 cells, was measured by the end of the late-log phase (90 AU ml?1) with a bacteriocine production rate of 9.3 (AU ml?1) h?1. In addition, our findings showed that the bacteriocin, produced by S. thermophilus T2, was stable over a wide pH range (4–8); this indicates that such bacteriocin may be useful in acidic as well as nonacidic food. This preliminarily work shows the potential application of autochthonous lactic acid bacteria to improve safety of traditional fermented food. PMID:20041021

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

2009-01-01

190

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

191

Siboglinid-bacteria endosymbiosis  

PubMed Central

Siboglinid worms are a group of gutless marine annelids which are nutritionally dependent upon endosymbiotic bacteria.1,2 Four major groups of siboglinids are known including vestimentiferans, Osedax spp., frenulates and moniliferans.3–5 Very little is known about the diversity of bacterial endosymbionts associated with frenulate or monoliferan siboglinids. This lack of knowledge is surprising considering the global distribution of siboglinids; this system is likely among the most common symbioses in the deep sea. At least three distinct clades of endosymbiotic ?-proteobacteria associate with siboglinid annelids.6 Frenulates harbor a clade of ?-proteobacteria that are divergent from both the thiotrophic bacteria of vestimentiferans and monoliferans as well as the heterotrophic bacteria of Osedax spp.6,7 We also discuss priorities for future siboglinid research and the need to move beyond descriptive studies. A promising new method, laser-capture microdissection (LCM), allows for the precise excision of tissue regions of interest.8 This method, when used in concert with molecular and genomic techniques, such as Expressed Sequence Tag (EST) surveys using pyrosequencing technology, will likely enable investigations into physiological processes and mechanisms in these symbioses. Furthermore, adopting a comparative approach using different siboglinid groups, such as worms harboring thiotrophic versus methanotrophic endosymbionts, may yield considerable insight into the ecology and evolution of the Siboglinidae. PMID:19704881

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

2008-01-01

192

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

193

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

194

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

195

Photocatalytic disinfection of spoilage bacteria Pseudomonas fluorescens and Macrococcus caseolyticus by nano-TiO2  

Technology Transfer Automated Retrieval System (TEKTRAN)

Photocatalytic disinfection of spoilage bacteria gram-negative (G-) P. fluorescens and gram-positive (G+) M. caseolyticus by nano-TiO2 under different experimental conditions and the disinfection mechanism were investigated. The experimental conditions included the initial bacterial populations, nan...

196

How bacteria talk to each other: regulation of gene expression by quorum sensing  

Microsoft Academic Search

Quorum sensing, or the control of gene expression in response to cell density, is used by both Gram-negative and Gram-positive bacteria to regulate a variety of physiological functions. In all cases, quorum sensing involves the production and detection of extracellular signalling molecules called autoinducers. While universal signalling themes exist, variations in the design of the extracellular signals, the signal detection

Bonnie L Bassler

1999-01-01

197

Triclosan- resistant bacteria isolated from feedlot and residential soils  

PubMed Central

Triclosan is an antimicrobial agent that is currently incorporated into hundreds of consumer and medical products. It can be either a bacteriostatic or bactericidal agent, depending on its formulation. It has activity against Gram-positive and Gram-negative bacteria, as well as some viruses and protists. The purpose of this study was to determine whether triclosan-resistant bacteria could be isolated from the soil. Soils from cattle feedlots and residential lawns were collected and assayed for the presence of these organisms by plating samples on growth media containing triclosan. Organisms were subsequently identified by partial 16S rRNA sequencing analysis. All the organisms isolated in this study were Gram-negative rods, with members of genus Pseudomonas being particularly well represented. This result may not be surprising because Gram-negative organisms are generally more resistant to triclosan, and since Pseudomonas bacteria are known to have numerous efflux mechanisms for dealing with harmful substances. PMID:21391038

WELSCH, TANNER T.; GILLOCK, ERIC T.

2014-01-01

198

Designing surfaces that kill bacteria on contact  

NASA Astrophysics Data System (ADS)

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

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

2001-05-01

199

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

200

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

201

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

Microsoft Academic Search

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

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

1997-01-01

202

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

2008-08-29

203

RNA localization in bacteria.  

PubMed

One of the most important discoveries in the field of microbiology in the last two decades is that bacterial cells have intricate subcellular organization. This understanding has emerged mainly from the depiction of spatial and temporal organization of proteins in specific domains within bacterial cells, e.g., midcell, cell poles, membrane and periplasm. Because translation of bacterial RNA molecules was considered to be strictly coupled to their synthesis, they were not thought to specifically localize to regions outside the nucleoid. However, the increasing interest in RNAs, including non-coding RNAs, encouraged researchers to explore the spatial and temporal localization of RNAs in bacteria. The recent technological improvements in the field of fluorescence microscopy allowed subcellular imaging of RNAs even in the tiny bacterial cells. It has been reported by several groups, including ours that transcripts may specifically localize in such cells. Here we review what is known about localization of RNA and of the pathways that determine RNA fate in bacteria, and discuss the possible cues and mechanisms underlying these distribution patterns. PMID:25482897

Buskila, Avi-Ad Avraam; Kannaiah, Shanmugapriya; Amster-Choder, Orna

2014-08-01

204

Bioinspired magneto-optical bacteria.  

PubMed

"Two-in-one" magneto-optical bacteria have been produced using the probiotic Lactobacillus fermentum for the first time. We took advantage of two features of bacteria to synthesize this novel and bifunctional nanostructure: their metal-reducing properties, to produce gold nanoparticles, and their capacity to incorporate iron oxide nanoparticles at their external surface. The magneto-optical bacteria survive the process and behave as a magnet at room temperature. PMID:25068183

Carmona, Fernando; Martín, Miguel; Gálvez, Natividad; Dominguez-Vera, Jose M

2014-08-18

205

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... Star Healthy Streams * ? Environmental Management of Grazing Lands * *TWRI-managed projects More information on the initiative is available at www.tsswcb.state.tx.us/managementprogram/ initiatives/bacteria. Bacteria Projects Across the State...

Wythe, Kathy

2007-01-01

206

Characterization of thermophilic bacteria using surface-enhanced Raman scattering.  

PubMed

Surface-enhanced Raman scattering (SERS) can provide molecular-level information about the molecules and molecular structures in the vicinity of nanostructured noble metal surfaces such as gold and silver. The three thermophilic bacteria Bacillus licheniformis, Geobacillus stearothermophilus, and Geobacillus pallidus, a Gram-negative bacterium E. coli, and a Gram-positive bacterium B. megaterium are comparatively characterized using SERS. The SERS spectra of thermophilic bacteria are similar, while they show significant differences compared to E. coli and B. megaterium. The findings indicate that a higher number of thiol residues and possible S-S bridges are present in the cell wall structure of thermophilic bacteria, providing their stability at elevated temperatures. Incubating the thermophilic bacteria with colloidal silver suspension at longer times improved the bacteria-silver nanoparticle interaction kinetics, while increased temperature does not have a pronounced effect on spectral features. A tentative assignment of the SERS bands was attempted for thermophilic bacteria. The results indicate that SERS can be a useful tool to study bacterial cell wall molecular differences. PMID:19007464

Culha, Mustafa; Adigüzel, Ahmet; Yazici, M Müge; Kahraman, Mehmet; Sahin, Fikrettin; Güllüce, Medine

2008-11-01

207

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

208

Light and electron microscopic studies of anaerobic curved bacteria isolated from the vagina.  

PubMed

Twenty strains of anaerobic curved rods isolated from vaginal secretion were studied with light and transmission electron microscopy. Ten of the strains were of a short (approx. 1.5 microns) Gram-variable type, while ten were of a long (approx. 3 microns) Gram-negative type. The former had one to four flagella and the latter between one and eight. The flagella originated from the concave aspect of the cells. Thin sections of both types of bacteria revealed an approximately 30 nm thick cell wall with no outer membrane, similar to that of most Gram-positive bacteria. An electron-dense zone in the middle of the cell wall, atypical of Gram-positive bacteria, was found, however. Amorphous and electron-translucent cytoplasmic inclusions, not membrane-enclosed, were detected. These inclusions stained metachromatically with Albert's stain. PMID:6598923

Skarin, A; Weibull, C; Mårdh, P A

1984-01-01

209

Bacteria tracking by in vivo magnetic resonance imaging  

PubMed Central

Background Different non-invasive real-time imaging techniques have been developed over the last decades to study bacterial pathogenic mechanisms in mouse models by following infections over a time course. In vivo investigations of bacterial infections previously relied mostly on bioluminescence imaging (BLI), which is able to localize metabolically active bacteria, but provides no data on the status of the involved organs in the infected host organism. In this study we established an in vivo imaging platform by magnetic resonance imaging (MRI) for tracking bacteria in mouse models of infection to study infection biology of clinically relevant bacteria. Results We have developed a method to label Gram-positive and Gram-negative bacteria with iron oxide nano particles and detected and pursued these with MRI. The key step for successful labeling was to manipulate the bacterial surface charge by producing electro-competent cells enabling charge interactions between the iron particles and the cell wall. Different particle sizes and coatings were tested for their ability to attach to the cell wall and possible labeling mechanisms were elaborated by comparing Gram-positive and -negative bacterial characteristics. With 5-nm citrate-coated particles an iron load of 0.015 ± 0.002 pg Fe/bacterial cell was achieved for Staphylococcus aureus. In both a subcutaneous and a systemic infection model induced by iron-labeled S. aureus bacteria, high resolution MR images allowed for bacterial tracking and provided information on the morphology of organs and the inflammatory response. Conclusion Labeled with iron oxide particles, in vivo detection of small S. aureus colonies in infection models is feasible by MRI and provides a versatile tool to follow bacterial infections in vivo. The established cell labeling strategy can easily be transferred to other bacterial species and thus provides a conceptual advance in the field of molecular MRI. PMID:23714179

2013-01-01

210

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

PubMed

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

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

2013-01-01

211

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

212

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.

213

Quorum Sensing Let Bacteria Talk  

Microsoft Academic Search

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

Indrani Bhattacharyya; Mayukh Choudhury

2008-01-01

214

Microcins from Enterobacteria: On the Edge Between Gram-Positive Bacteriocins and Colicins  

NASA Astrophysics Data System (ADS)

Most bacteria and archaea produce gene-encoded antimicrobial peptides/proteins called bacteriocins, which are secreted by the producing bacteria to compete against other microorganisms in a given niche. They are considered important mediators of intra- and interspecies interactions and therefore a factor in ­maintaining the microbial diversity and stability. They are ribosomally synthesized, and most of them are produced as inactive precursor proteins, which in some cases are further enzymatically modified. Bacteriocins generally exert potent antibacterial activities directed against bacterial species closely related to the producing bacteria. Bacteriocins are abundant and diverse in Gram-negative and Gram-positive bacteria. This chapter focuses on colicins and microcins from enterobacteria (mainly Escherichia coli) and on bacteriocins from lactic acid bacteria (LAB). Microcins are the lower-molecular-mass bacteriocins produced by Gram-negative bacteria with a repertoire of only 14 representatives. They form a very restricted family of bacteriocins, compared to the huge family of LAB bacteriocins that is constituted of several hundreds of peptides, with which microcins share common characteristics. Nevertheless, microcins also show similarities, particularly in their uptake mechanisms, with the higher-molecular-mass colicins, also produced by E. coli strains. On the edge between LAB bacteriocins and colicins, microcins appear to combine highly efficient strategies developed by both Gram-positive and Gram-negative bacteria at different levels, including uptake, translocation, killing of target cells, and immunity of the producing bacteria, making them important actors of bacterial competitions and fascinating models for novel concepts toward antimicrobial strategies and against resistance mechanisms.

Rebuffat, Sylvie

215

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

216

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.

217

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

218

Inactivation ofBiofilm Bacteria  

Microsoft Academic Search

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

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

1988-01-01

219

Antagonistic effect of oral bacteria towards Treponema denticola.  

PubMed Central

This study was designed to isolate oral bacteria exhibiting antagonism towards Treponema denticola and to characterize the inhibitory activity. Eleven bacterial isolates obtained from subgingival sites and identified as either Staphylococcus aureus or Streptococcus mutans were found to inhibit the growth of T. denticola. When the activity spectra of these isolates were analyzed, two additional periodontopathogens (Porphyromonas gingivalis and Prevotella intermedia) were found to be affected, whereas most gram-positive bacteria were not. Strains of S. aureus produce a bacteriocin-like inhibitory substance (heat stable and protease sensitive), whereas the inhibitory effect of S. mutans appears to be related to the production of lactic acid. The negative interactions reported in this paper may govern population shifts observed in subgingival sites. PMID:8727911

Grenier, D

1996-01-01

220

Development of Mucosal Vaccines Based on Lactic Acid Bacteria  

NASA Astrophysics Data System (ADS)

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

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

221

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

222

Mechanism of action of recombinant Acc-royalisin from royal jelly of Chinese honeybee against gram-positive bacteria  

Technology Transfer Automated Retrieval System (TEKTRAN)

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 Chinese honeybee Apis cerana...

223

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

224

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

Microsoft Academic Search

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

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

2002-01-01

225

High osmolarity improves the electro-transformation efficiency of the gram-positive bacteria Bacillus subtilis and Bacillus licheniformis  

Microsoft Academic Search

A high osmolarity electroporation method has been developed for the efficient transformation of Bacillus subtilis and B. licheniformis. The presence of high concentrations of the osmoticums, sorbitol and mannitol, in the electroporation, growth and recovery media resulted in an approximately 5000-fold increase in the transformation efficiency of B. subtilis, with a maximum value of 1.4×106 transformants per ?g DNA. The

Gang-Ping Xue; Jennifer S Johnson; Brian P Dalrymple

1999-01-01

226

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

227

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

PubMed Central

Strain NRRL B-30745, isolated from chicken ceca and identified as Enterococcus durans, Enterococcus faecium, or Enterococcus hirae, was initially identified as antagonistic to Campylobacter jejuni. The isolate produced a 5,362-Da bacteriocin (enterocin) that inhibits the growth of Salmonella enterica serovar Enteritidis, S. enterica serovar Choleraesuis, S. enterica serovar Typhimurium, S. enterica serovar Gallinarum, Escherichia coli O157:H7, Yersinia enterocolitica, Citrobacter freundii, Klebsiella pneumoniae, Shigella dysenteriae, Pseudomonas aeruginosa, Proteus mirabilis, Morganella morganii, Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes, Campylobacter jejuni, and 20 other Campylobacter species isolates. The enterocin, E-760, was isolated and purified by cation-exchange and hydrophobic-interaction chromatographies. The proteinaceous nature of purified enterocin E-760 was demonstrated upon treatment with various proteolytic enzymes. Specifically, the antimicrobial peptide was found to be sensitive to beta-chymotrypsin, proteinase K, and papain, while it was resistant to lysozyme and lipase. The enterocin demonstrated thermostability by retaining activity after 5 min at 100°C and was stable at pH values between 5.0 and 8.7. However, activity was lost below pH 3.0 and above pH 9.5. Administration of enterocin E-760-treated feed significantly (P < 0.05) reduced the colonization of young broiler chicks experimentally challenged and colonized with two strains of C. jejuni by more than 8 log10 CFU. Enterocin E-760 also significantly (P < 0.05) reduced the colonization of naturally acquired Campylobacter species in market age broiler chickens when administered in treated feed 4 days prior to analysis. PMID:18086839

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

2008-01-01

228

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

229

Design and synthesis of novel antimicrobials with activity against Gram-positive bacteria and mycobacterial species, including M. tuberculosis  

PubMed Central

The alarming increase in bacterial resistance over the last decade along with a dramatic decrease in new treatments for infections has led to problems in the healthcare industry. Tuberculosis (TB) is caused mainly by Mycobacterium tuberculosis which is responsible for 1.4 million deaths per year. A world-wide threat with HIV co-infected with multi and extensively drug-resistant strains of TB has emerged. In this regard, herein, novel acrylic acid ethyl ester derivatives were synthesized in simple, efficient routes and evaluated as potential agents against several Mycobacterium species. These were synthesized via a stereospecific process for structure activity relationship (SAR) studies. Minimum inhibitory concentration (MIC) assays indicated that esters 12, 13, and 20 exhibited greater in vitro activity against Mycobacterium smegmatis than rifampin, one of the current, first-line anti-mycobacterial chemotherapeutic agents. Based on these studies the acrylic ester 20 has been developed as a potential lead compound which was found to have an MIC value of 0.4 ?g/mL against Mycobacterium tuberculosis. The SAR and biological activity of this series is presented; a Michael – acceptor mechanism appears to be important for potent activity of this series of analogs. PMID:24200931

Tiruveedhula, V.V.N. Phani Babu; Witzigmann, Christopher M.; Verma, Ranjit; Kabir, M. Shahjahan; Rott, Marc; Schwan, William R.; Medina-Bielski, Sara; Lane, Michelle; Close, William; Polanowski, Rebecca L.; Sherman, David; Monte, Aaron; Deschamps, Jeffrey R.; Cook, James M.

2013-01-01

230

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

Microsoft Academic Search

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

Sandrine Rousseaux; Alain Hartmann; Guy Soulas

2001-01-01

231

Gram-Positive Nickel Resistant Bacteria Isolated from Riparian Sediments Contaminated with Ni and U on the Savannah River Site  

Microsoft Academic Search

The natural attenuation of pollutants in riparian and wetland systems is driven in large part by the services provided by the diverse microbial communities that thrive in these nutritionally and chemically complex environments. For co-contaminated systems, the presence of heavy metals at excessive levels may alter the structure and function of microbial communities that are essential for the immobilization of

A. G. Sowder; T. V. Khijniak; J. van Nostrand; P. M. Bertsch; P. J. Morris

2002-01-01

232

Bees Scavenge Airborne Bacteria.  

PubMed

An air conditioned wind tunnel system was designed, fabricated, and tested to determine whether tethered bees scavenge microbeads or Bacillus subtilis var. niger spores from aerosols. Tests showed that microbeads and spores were scavenged by bumblebees and honeybees, respectively. Five independent variables and their interactions were used in a stepwise multiple regression. Two of them, the cube root of the electrostatic charge on the honeybee and the dose of the spore aerosol, accounted for most of the statistically significant fit to the model's two dependent variables: the percentage of the dose adsorbed by honeybees and the number of spores adsorbed by the same bees. Both dependent variables increased directly so that an increase in electrostatic charge on the bee (i.e., cube root 32 pC) resulted in an increase (i.e., approximately 1%) in the spore dose adsorbed and the number of spores adsorbed by the bees. It was theorized that the spores were in an adsorption/desorption equilibrium that responded to the concentration "pressure" of the spore aerosol. Further, the charge on the bee affected the adsorption force on the bee's surface, as well as increasing the effective aerosol volume accessible for the bee's scavenging. In short, relating these findings to bees scavenging bacteria from the ambient atmosphere, it appears that the spore exposure (where exposure means the product of the ambient concentration, the time the bee is exposed, and air volume through which the bee flies) controls the number of spores adsorbed by a bee, and the static charge on the bee controls the adsorption/desorption equilibrium and presumably the scavenging volume. PMID:10882436

Lighthart; Prier; Loper; Bromenshenk

2000-05-01

233

Gram-positive bacterial resistance. A challenge for the next millennium.  

PubMed

Penicillin G was first used in 1941. Since then, the trend in bacterial infections has changed. New antibiotics have been developed and bacterial resistance has spread as a consequence. The spread of Gram positive resistant bacteria is related to an inappropriate use of antibiotics. Antibacterial agents are abused or overused in various fields: medicine itself, veterinary science and zootechnics. Now, at the beginning of the third millennium we have been forced to limit our therapeutic options in order to combat these insidious enemies. Selective antibiotic pressure on the microbial population, notably on enterococci and staphylococci, made these two pathogens recalcitrant to traditional chemotherapy. It is a matter of concern that today, vancomycin-resistant Enterococcus spp. (VRE) and vancomycin-intermediate and resistant Staphylococcus aureus (VISA and VRSA) are now being observed worldwide among emerging pathogens. Most pharmaceutical companies are today developing antimicrobial drugs that are active against Gram-positive bacteria. Quinupristin/dalfopristin and linezolid are the most promising drugs and are available only for serious infections; future agents being developed for multi-resistant Gram-positive infections include daptomycin and the glycyclines, although these are still in the development phase. Nevertheless, our group has had the opportunity to treat some serious infections with these drugs and the good results achieved are reported in this review. PMID:12094131

Bassetti, M; Melica, G; Cenderello, G; Rosso, R; Di Biagio, A; Bassetti, D

2002-09-01

234

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

235

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

236

Ability of dairy strains of lactic acid bacteria to bind a common food carcinogen, aflatoxin B 1  

Microsoft Academic Search

This study was conducted to examine the ability of selected dairy strains of lactic acid bacteria to remove aflatoxin B1 (AFB1) from liquid media. Both Lactobacillus rhamnosus strain GG (LBGG) and L. rhamnosus strain LC-705 (LC705) can significantly (P>0.05) remove AFB1 when compared with that by other strains of either Gram-positive or Gram-negative bacteria. Removal of AFB1 by LBGG and

H. El-Nezami; P. Kankaanpaa; S. Salminen; J. Ahokas

1998-01-01

237

Mechanism of gram variability in select bacteria.  

PubMed

Gram stains were performed on strains of Actinomyces bovis, Actinomyces viscosus, Arthrobacter globiformis, Bacillus brevis, Butyrivibrio fibrisolvens, Clostridium tetani, Clostridium thermosaccharolyticum, Corynebacterium parvum, Mycobacterium phlei, and Propionibacterium acnes, using a modified Gram regimen that allowed the staining process to be observed by electron microscopy (J. A. Davies, G. K. Anderson, T. J. Beveridge, and H. C. Clark, J. Bacteriol. 156:837-845, 1983). Furthermore, since a platinum salt replaced the iodine mordant of the Gram stain, energy-dispersive X-ray spectroscopy could evaluate the stain intensity and location by monitoring the platinum signal. These gram-variable bacteria could be split into two groups on the basis of their staining responses. In the Actinomyces-Arthrobacter-Corynebacterium-Mycobacterium-Propionibacterium group, few cells became gram negative until the exponential growth phase; by mid-exponential phase, 10 to 30% of the cells were gram negative. The cells that became gram negative were a select population of the culture, had initiated septum formation, and were more fragile to the stress of the Gram stain at the division site. As cultures aged to stationary phase, there was a relatively slight increase toward gram negativity (now 15 to 40%) due to the increased lysis of nondividing cells by means of lesions in the side walls; these cells maintained their rod shape but stained gram negative. Those in the Bacillus-Butyrivibrio-Clostridium group also became gram negative as cultures aged but by a separate set of events. These bacteria possessed more complex walls, since they were covered by an S layer. They stained gram positive during lag and the initial exponential growth phases, but as doubling times increased, the wall fabric underlying the S layer became noticeably thinner and diffuse, and the cells became more fragile to the Gram stain. By stationary phase, these cultures were virtually gram negative. PMID:1689718

Beveridge, T J

1990-03-01

238

Genetic resources of nodule bacteria  

Microsoft Academic Search

Nodule bacteria (rhizobia) form highly specific symbiosis with leguminous plants. The efficiency of accumulation of biological\\u000a nitrogen depends on molecular-genetic interaction between the host plant and rhizobia. Genetic characteristics of microsymbiotic\\u000a strains are crucial in developing highly productive and stress-resistant symbiotic pairs: rhizobium strain-host plant cultivar\\u000a (species). The present review considers the issue of studying genetic resources of nodule bacteria

M. L. Roumiantseva

2009-01-01

239

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

240

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

241

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

242

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

243

[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

244

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

245

Host-Bacteria Crosstalk at the Dentogingival Junction  

PubMed Central

The dentogingival junction is of crucial importance in periodontal host defense both structurally and functionally. Oral bacteria exert a constant challenge to the host cells and tissues at the dentogingival junction. The host response is set up to eliminate the pathogens by the innate and adaptive defense mechanisms. In health, the commensal bacteria and the host defense mechanisms are in a dynamic steady state. During periodontal disease progression, the dental bacterial plaque, junctional epithelium (JE), inflammatory cells, connective tissue, and bone all go through a series of changes. The tissue homeostasis is turned into tissue destruction and progression of periodontitis. The classical study of Slots showed that in the bacterial plaque, the most remarkable change is the shift from gram-positive aerobic and facultatively anaerobic flora to a predominantly gram-negative and anaerobic flora. This has been later confirmed by several other studies. Furthermore, not only the shift of the bacterial flora to a more pathogenic one, but also bacterial growth as a biofilm on the tooth surface, allows the bacteria to communicate with each other and exert their virulence aimed at favoring their growth. This paper focuses on host-bacteria crosstalk at the dentogingival junction and the models studying it in vitro. PMID:22899931

Pöllänen, M. T.; Laine, M. A.; Ihalin, R.; Uitto, V.-J.

2012-01-01

246

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

PubMed Central

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. PMID:16269798

Ishida, Yasuyuki; Kitagawa, Kuniyuki; Nakayama, Akihito; Ohtani, Hajime

2005-01-01

247

Gene replacement of adenylate kinase in the gram-positive thermophile Geobacillus stearothermophilus disrupts adenine nucleotide homeostasis and reduces cell viability  

Microsoft Academic Search

Thermophilic bacteria are of great value for industry and research communities. Unfortunately, the cellular processes and mechanisms of these organisms remain largely understudied. In the present study, we investigate how the inactivation of adenylate kinase (AK) affects the adenine nucleotide homeostasis of a gram-positive moderate thermophile, Geobacillus stearothermophilus strain NUB3621-R. AK plays a major role in the adenine nucleotide homeostasis

Rafael Couñago; Yousif Shamoo

2005-01-01

248

Subgingival bacteria--comparison of culture results in dogs and cats with gingivitis.  

PubMed

Aerobic and anaerobic subgingival bacteria were cultured and identified from 49 dogs and 40 cats with spontaneous gingivitis. The most common organisms were gram-negative anaerobes (37% of canine isolates and 39% of feline isolates) and gram-positive aerobes (36% of canine isolates and 29% of feline isolates). No major differences were found between the subgingival floras of dogs and cats with gingivitis. PMID:9693642

Harvey, C E; Thornsberry, C; Miller, B R

1995-12-01

249

Effects of Alternative Dietary Substrates on Competition between Human Colonic Bacteria in an Anaerobic Fermentor System  

Microsoft Academic Search

Duplicate anaerobic fermentor systems were used to examine changes in a community of human fecal bacteria supplied with different carbohydrate energy sources. A panel of group-specific fluorescent in situ hybridization probes targeting 16S rRNA sequences revealed that the fermentors supported growth of a greater proportion of Bacteroides and a lower proportion of gram-positive anaerobes related to Faecalibacterium prausnitzii, Ruminococcus flavefaciens-Ruminococcus

Sylvia H. Duncan; Karen P. Scott; Alan G. Ramsay; Hermie J. M. Harmsen; Gjalt W. Welling; Colin S. Stewart; Harry J. Flint

2003-01-01

250

Isolation and characterization of endophytic bacteria from wild and traditionally cultivated rice varieties  

Microsoft Academic Search

Endophytic bacteria were isolated from surface-sterilized stems, seeds, and leaf sheaths of wild and traditionally cultivated rice varieties. Phylogenetic analyses based on 16S rDNA revealed a wide divergence among the isolates. However, the most frequently isolated groups were Methylobacterium sp. in the ?-subdivision of Proteobacteria, and Curtobacterium sp. in the high G+ C Gram-positive group. Various phenotypic traits that are

Adel Elbeltagy; Kiyo Nishioka; Hisa Suzuki; Tadashi Sato; Yo-Ichiro Sato; Hisao Morisaki; Hisayuki Mitsui; Kiwamu Minamisawa

2000-01-01

251

Cadmium Ion Biosorption by the Thermophilic Bacteria Geobacillus stearothermophilus and G. thermocatenulatus  

Microsoft Academic Search

This study reports surface complexation models (SCMs) for quantifying metal ion adsorption by thermo- philic microorganisms. In initial cadmium ion toxicity tests, members of the genus Geobacillus displayed the highest tolerance to CdCl2 (as high as 400 to 3,200 M). The thermophilic, gram-positive bacteria Geobacillus stearothermophilus and G. thermocatenulatus were selected for further electrophoretic mobility, potentiometric titration, and Cd2 adsorption

Adrian Hetzer; Christopher J. Daughney; Hugh W. Morgan

2006-01-01

252

Metabolism of Linoleic Acid by Human Gut Bacteria: Different Routes for Biosynthesis of Conjugated Linoleic Acid?  

PubMed Central

A survey of 30 representative strains of human gram-positive intestinal bacteria indicated that Roseburia species were among the most active in metabolizing linoleic acid (cis-9,cis-12-18:2). Different Roseburia spp. formed either vaccenic acid (trans-11-18:1) or a 10-hydroxy-18:1; these compounds are precursors of the health-promoting conjugated linoleic acid cis-9,trans-11-18:2 in human tissues and the intestine, respectively. PMID:17209019

Devillard, Estelle; McIntosh, Freda M.; Duncan, Sylvia H.; Wallace, R. John

2007-01-01

253

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

254

Vancomycin-resistant gram-positive cocci isolated from the saliva of wild songbirds.  

PubMed

We analyzed highly vancomycin-resistant Gram-positive bacteria isolated from the saliva of migratory songbirds captured, sampled, and released from a bird-banding station in western Kansas. Individual bacterial isolates were identified by partial 16S rRNA sequencing. Most of the bacteria in this study were shown to be Staphylococcus succinus with the majority being isolated from the American Robin. Some of these bacteria were shown to carry vanA, vanB, and vanC vancomycin-resistance genes and have the ability to form biofilms. One of the van gene-carrying isolates is also coagulase positive, which is normally considered a virulence factor. Other organisms isolated included Staphylococcus saprophyticus as well as Enterococcus gallinarum. Given the wide range of the American Robin and ease of horizontal gene transfer between Gram-positive cocci, we postulate that these organisms could serve as a reservoir of vancomycin-resistance genes capable of transferring to human pathogens. PMID:23224296

Ishihara, Shingo; Bitner, Jessica J; Farley, Greg H; Gillock, Eric T

2013-04-01

255

Tunable protein degradation in bacteria.  

PubMed

Tunable control of protein degradation in bacteria would provide a powerful research tool. Here we use components of the Mesoplasma florum transfer-messenger RNA system to create a synthetic degradation system that provides both independent control of steady-state protein level and inducible degradation of targeted proteins in Escherichia coli. We demonstrate application of this system in synthetic circuit development and control of core bacterial processes and antibacterial targets, and we transfer the system to Lactococcus lactis to establish its broad functionality in bacteria. We create a 238-member library of tagged essential proteins in E. coli that can serve as both a research tool to study essential gene function and an applied system for antibiotic discovery. Our synthetic protein degradation system is modular, does not require disruption of host systems and can be transferred to diverse bacteria with minimal modification. PMID:25402616

Cameron, D Ewen; Collins, James J

2014-12-01

256

Genetic transfer in acidophilic bacteria  

SciTech Connect

There is increasing interest in the use of microorganisms to recover metals from ores, as well as to remove sulfur from coal. These so-called bioleaching processes are mediated by a number of bacteria. The best-studied of these organisms are acidophiles including Thiobacillus and Acidiphilium species. Our laboratory has focused on developing genetic strategies to allow the manipulation of acidophilic bacteria to improve and augment their utility in large scale operations. We have recently been successful in employing conjugation for interbacterial transfer of genetic information, as well as in directly transforming Acidiphilium by use of electroporation. We are now testing the properties of IncPl, IncW and IncQ plasmid vectors in Acidiphilium to determine their relative usefulness in routine manipulation of acidophiles and transfer between organisms. This study also allows us to determine the natural ability of these bacteria to transfer genetic material amongst themselves in their particular environment. 21 refs., 3 figs., 2 tabs.

Roberto, F.F.; Glenn, A.W.; Bulmer, D.; Ward, T.E.

1990-01-01

257

Commensal bacteria and cutaneous immunity.  

PubMed

The skin is the human body's largest organ and is home to a diverse and complex variety of innate and adaptive immune functions that protect against pathogenic invasion. Recent studies have demonstrated that cutaneous commensal bacteria modulated the host immune system. For example, Staphylococcus epidermidis, a skin commensal bacterium, has been demonstrated to induce cutaneous interferon (IFN)-?- and interleukin (IL)-17A-producing T cells. In addition, cutaneous microbiota changes occur in the chronic inflammatory skin disorders, such as atopic dermatitis, and may influence the activity of skin diseases. In this article, we will review the recent findings related to the interactions of the commensal bacteria with skin homeostasis and discuss the role of the dysbiosis of these bacteria in the pathogenesis of skin diseases. PMID:25326105

Nakamizo, Satoshi; Egawa, Gyohei; Honda, Tetsuya; Nakajima, Saeko; Belkaid, Yasmine; Kabashima, Kenji

2015-01-01

258

Carbon metabolism of intracellular bacteria.  

PubMed

Bacterial metabolism has been studied intensively since the first observations of these 'animalcules' by Leeuwenhoek and their isolation in pure cultures by Pasteur. Metabolic studies have traditionally focused on a small number of model organisms, primarily the Gram negative bacillus Escherichia coli, adapted to artificial culture conditions in the laboratory. Comparatively little is known about the physiology and metabolism of wild microorganisms living in their natural habitats. For approximately 500-1000 species of commensals and symbionts, and a smaller number of pathogenic bacteria, that habitat is the human body. Emerging evidence suggests that the metabolism of bacteria grown in vivo differs profoundly from their metabolism in axenic cultures. PMID:16367862

Muñoz-Elías, Ernesto J; McKinney, John D

2006-01-01

259

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

260

Bacteria Living in Extreme Environments  

NSDL National Science Digital Library

In this activity, students will develop an experiment that will test the ability of bacteria to survive various temperature extremes. They will grow the bacteria in nutrient broth, which will be placed in different temperatures for at least 24 hours and then spread on nutrient agar plates and incubated at 37 degrees Celcius for an additional 24 hours. Students will: learn how to formulate and test their own experimental questions; learn sterile technique; gather and analyze data collected from their experiments; propose ideas/questions for further experimentation; and develop and improve their communication skills as they present results to their peers.

Glenn Zwanzig

261

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

262

Chip-based in situ hybridization for identification of bacteria from the human microbiome.  

SciTech Connect

The emerging field of metagenomics seeks to assess the genetic diversity of complex mixed populations of bacteria, such as those found at different sites within the human body. A single person's mouth typically harbors up to 100 bacterial species, while surveys of many people have found more than 700 different species, of which {approx}50% have never been cultivated. In typical metagenomics studies, the cells themselves are destroyed in the process of gathering sequence information, and thus the connection between genotype and phenotype is lost. A great deal of sequence information may be generated, but it is impossible to assign any given sequence to a specific cell. We seek non-destructive, culture-independent means of gathering sequence information from selected individual cells from mixed populations. As a first step, we have developed a microfluidic device for concentrating and specifically labeling bacteria from a mixed population. Bacteria are electrophoretically concentrated against a photopolymerized membrane element, and then incubated with a specific fluorescent label, which can include antibodies as well as specific or non-specific nucleic acid stains. Unbound stain is washed away, and the labeled bacteria are released from the membrane. The stained cells can then be observed via epifluorescence microscopy, or counted via flow cytometry. We have tested our device with three representative bacteria from the human microbiome: E. coli (gut, Gram-negative), Lactobacillus acidophilus (mouth, Gram-positive), and Streptococcus mutans (mouth, Gram-positive), with results comparable to off-chip labeling techniques.

Light, Yooli Kim; Meagher, Robert J.; Singh, Anup K.; Liu, Peng

2010-11-01

263

Diversity and distribution of alkaliphilic psychrotolerant bacteria in the Qinghai-Tibet Plateau permafrost region.  

PubMed

The Qinghai-Tibet Plateau represents a unique permafrost environment, being a result of high elevation caused by land uplift. And the urgency was that plateau permafrost was degrading rapidly under the current predicted climatic warming scenarios. Hence, the permafrost there was sampled to recover alkaliphilic bacteria populations. The viable bacteria on modified PYGV agar were varied between 10(2) and 10(5 )CFU/g of dry soil. Forty-eight strains were gained from 18 samples. Through amplified ribosomal DNA restriction analysis (ARDRA) and phylogenetic analyses, these isolates fell into three categories: high G + C gram positive bacteria (82.3%), low G + C gram positive bacteria (7.2%), and gram negative alpha-proteobacteria (10.5%). The strains could grow at pH values ranging from 6.5 to 10.5 with optimum pH in the range of 9-9.5. Their growth temperatures were below 37 degrees C and the optima ranging from 10 to 15 degrees C. All strains grew well when NaCl concentration was below 15%. These results indicate that there are populations of nonhalophilic alkaliphilic psychrotolerant bacteria within the permafrost of the Qinhai-Tibet plateau. The abilities of many of the strains to produce extracellular protease, amylase and cellulase suggest that they might be of potential value for biotechnological exploitation. PMID:17487445

Zhang, Gaosen; Ma, Xiaojun; Niu, Fujun; Dong, Maoxing; Feng, Huyuan; An, Lizhe; Cheng, Guodong

2007-05-01

264

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

265

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

266

Manipulating Genetic Material in Bacteria  

NASA Technical Reports Server (NTRS)

Lisa Crawford, a graduate research assistant from the University of Toledo, works with Laurel Karr of Marshall Space Flight Center (MSFC) in the molecular biology laboratory. They are donducting genetic manipulation of bacteria and yeast for the production of large amount of desired protein. Photo credit: NASA/Marshall Space Flight Center (MSFC)

1998-01-01

267

The sulphate-reducing bacteria  

Microsoft Academic Search

This monograph surveys knowledge about an unusual and little-studied group of microbes, bringing together information that has hitherto been widely scattered throughout the scientific literature. The sulphate-reducing bacteria cannot grow in air; they respire sulphates instead of oxygen and are difficult to isolate and study. Nevertheless, much progress has been made in recent years and has revealed novelties of biochemistry

1984-01-01

268

Count, identification and antimicrobial susceptibility of bacteria recovered from dental solid waste in Brazil.  

PubMed

In Brazil, few studies on microbial content of dental solid waste and its antibiotic susceptibility are available. An effort has been made through this study to evaluate the hazardous status of dental solid waste, keeping in mind its possible role in cross-infection chain. Six samples of solid waste were collected at different times and seasons from three dental health services. The microbial content was evaluated in different culture media and atmospheric conditions, and the isolates were submitted to antibiotic susceptibility testing. A total of 766 bacterial strains were isolated and identified during the study period. Gram-positive cocci were the most frequent morphotype isolated (48.0%), followed by Gram-negative rods (46.2%), Gram-positive rods (5.0%), Gram-negative-cocci (0.4%), and Gram-positive coccobacillus (0.1%). Only two anaerobic bacteria were isolated (0.3%). The most frequently isolated species was Staphylococcus epidermidis (29.9%), followed by Stenotrophomonas maltophilia (8.2%), and Enterococcus faecalis (6.7%). High resistance rate to ampicillin was observed among Gram-negative rods (59.4%) and Gram-positive cocci (44.4%). For Gram-negative rods, high resistance was also noted to aztreonam (47.7%), cefotaxime (47.4%), ceftriaxone and cefazolin (43.7%), and ticarcillin-clavulanic acid (38.2%). Against Gram-positive cocci penicillin exhibit a higher resistance rate (45.0%), followed by ampicillin, erythromycin (27.2%), and tetracycline (22.0%). The present study demonstrated that several pathogenic bacteria are present in dental solid waste and can survive after 48 h from the waste generation time and harbor resistance profiles against several clinical recommended antibiotics. PMID:21288707

Vieira, Cristina Dutra; de Carvalho, Maria Auxiliadora Roque; Cussiol, Noil Amorim de Menezes; Alvarez-Leite, Maria Eugênia; dos Santos, Simone Gonçalves; Gomes, Renata Maria da Fonseca; Silva, Marcos Xavier; Nicoli, Jacques Robert; Farias, Luiz de Macêdo

2011-06-01

269

Rhs proteins from diverse bacteria mediate intercellular competition.  

PubMed

Rearrangement hotspot (Rhs) and related YD-peptide repeat proteins are widely distributed in bacteria and eukaryotes, but their functions are poorly understood. Here, we show that Gram-negative Rhs proteins and the distantly related wall-associated protein A (WapA) from Gram-positive bacteria mediate intercellular competition. Rhs and WapA carry polymorphic C-terminal toxin domains (Rhs-CT/WapA-CT), which are deployed to inhibit the growth of neighboring cells. These systems also encode sequence-diverse immunity proteins (RhsI/WapI) that specifically neutralize cognate toxins to protect rhs(+)/wapA(+) cells from autoinhibition. RhsA and RhsB from Dickeya dadantii 3937 carry nuclease domains that degrade target cell DNA. D. dadantii 3937 rhs genes do not encode secretion signal sequences but are linked to hemolysin-coregulated protein and valine-glycine repeat protein G genes from type VI secretion systems. Valine-glycine repeat protein G is required for inhibitor cell function, suggesting that Rhs may be exported from D. dadantii 3937 through a type VI secretion mechanism. In contrast, WapA proteins from Bacillus subtilis strains appear to be exported through the general secretory pathway and deliver a variety of tRNase toxins into neighboring target cells. These findings demonstrate that YD-repeat proteins from phylogenetically diverse bacteria share a common function in contact-dependent growth inhibition. PMID:23572593

Koskiniemi, Sanna; Lamoureux, James G; Nikolakakis, Kiel C; t'Kint de Roodenbeke, Claire; Kaplan, Michael D; Low, David A; Hayes, Christopher S

2013-04-23

270

New Antibiotic May Combat Resistant Bacteria  

MedlinePLUS

... please enable JavaScript. New Antibiotic May Combat Resistant Bacteria Teixobactin shows promise in early experiments, researchers say (* ... that could prove valuable in fighting disease-causing bacteria that no longer respond to older, more frequently ...

271

Barbecue Bliss: Keeping Bacteria at Bay  

MedlinePLUS

... Blood & Biologics Articulos en Espanol Barbecue Bliss: Keeping Bacteria at Bay Search the Consumer Updates Section Get ... your list. Summer brings out barbecue grills—and bacteria, which multiply in food faster in warm weather ...

272

Biodegradation of chlorobenzene by indigenous bacteria  

Microsoft Academic Search

Soil and ground water from four sites chronically contaminated with chlorobenzenes were examined to determine whether indigenous bacteria could degrade the contaminants and whether the addition of specific chlorobenzene-degrading bacteria enhanced the degradation rate. At each site, chlorobenzene-degrading bacteria were readily isolated from chlorobenzene-contaminated wells, whereas similar samples from noncontaminated wells yielded no chlorobenzene-degrading bacteria. Isolates were tested for growth

Shirley F Nishino; Jim C Spain; Charles A Pettigrew

1994-01-01

273

Re-engineering bacteria for ethanol production  

DOEpatents

The invention provides recombinant bacteria, which comprise a full complement of heterologous ethanol production genes. Expression of the full complement of heterologous ethanol production genes causes the recombinant bacteria to produce ethanol as the primary fermentation product when grown in mineral salts medium, without the addition of complex nutrients. Methods for producing the recombinant bacteria and methods for producing ethanol using the recombinant bacteria are also disclosed.

Yomano, Lorraine P; York, Sean W; Zhou, Shengde; Shanmugam, Keelnatham; Ingram, Lonnie O

2014-05-06

274

Nitrogen-fixing methane-utilizing bacteria  

Microsoft Academic Search

Methane occurs abundantly in nature. In the presence of oxygen this gas may be metabolized by bacteria that are able to use it as carbon and energy source. Several types of bacteria involved in the oxidation of methane have been described in literature. Methane-utilizing bacteria have in common that they can only grow on methane or methanol and not on

Bont de J. A. M

1976-01-01

275

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

276

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

277

Laser-Based Identification of Pathogenic Bacteria  

ERIC Educational Resources Information Center

Bacteria are ubiquitous in our world. From our homes, to our work environment, to our own bodies, bacteria are the omnipresent although often unobserved companions to human life. Physicists are typically untroubled professionally by the presence of these bacteria, as their study usually falls safely outside the realm of our typical domain. In the…

Rehse, Steven J.

2009-01-01

278

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

279

Molecular Cell Mixed Messages: How Bacteria  

E-print Network

Molecular Cell Previews Mixed Messages: How Bacteria Resolve Conflicting Signals Jonathan W. Young1 new study by Bollenbach and Kishony (2011) in this issue of Molecular Cell shows how bacteria resolve conflicting signals. In this issue, Bollenbach and Kishony (2011) analyze how bacteria solve these problems

Elowitz, Michael

280

Sexual isolation in bacteria Jacek Majewski *  

E-print Network

pressures during their evolutionary history. Not only can bacteria have sex, they are extremely promiscuous. There are documented cases of exchange of genetic material between bacteria, archea, plants and yeast [1]. Inter in bacteria occurs through three mechanisms: natural transformation, conjugation and transduction

Majewski, Jacek

281

Original article Mycorrhization helper bacteria associated  

E-print Network

for soil disinfection before inoculating might be reduced. ectomycorrhizas / bacteria / rhizosphereOriginal article Mycorrhization helper bacteria associated with the Douglas fir-Laccaria laccata could be improved by such mycor- rhization helper bacteria (MHB). The results with T terrestris suggest

Paris-Sud XI, Université de

282

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.

283

Homopolysaccharides from lactic acid bacteria  

Microsoft Academic Search

In addition to heteropolysaccharides of complex structure, lactic bacteria produce a variety of homopolysaccharides containing only either d-fructose or d-glucose. These fructans and glucans have a common feature in being synthesized by extracellular transglycosylases (glycansucrases) using sucrose as glycosyl donor. The energy of the osidic bond of sucrose enables the efficient transfer of a d-fructosyl or d-glucosyl residue via the

Pierre Monsan; Sophie Bozonnet; Cécile Albenne; Gilles Joucla; René-Marc Willemot; Magali Remaud-Siméon

2001-01-01

284

Lima Bean Bacteria DNA Extraction  

NSDL National Science Digital Library

This laboratory exercise is designed to show learners how DNA can easily be extracted from lima bean bacteria. This experiment requires the use of a centrifuge (not included in cost of materials). Use this experiment to supplement any unit on genetics and to demonstrate how scientists study DNA. Adult supervision is recommended. This resource guide includes tips and suggestions for instructors as well as other DNA extraction experiments and a chart for learners to answer questions.

Lana Hays

2009-01-01

285

Bacteria turn a tiny gear  

SciTech Connect

Thousands of tiny Bacillus subtillis bacteria turn a single gear, just 380 microns across. (A human hair is about 100 microns across.) The method could be used to create micro-machines. Argonne National Laboratory scientist Igor Aronson pioneered this technique. Read more at the New York Times: http://ow.ly/ODfI or at Argonne: http://ow.ly/ODfa Video courtesy Igor Aronson.

None

2009-01-01

286

Extremophilic Bacteria and Microbial Diversity  

NSDL National Science Digital Library

This online enhancement chapter of Raven and Johnson's Biology, a textbook for undergraduate majors, examines the many prokaryotic organisms that inhabit "extreme environments"ìñhabitats in which some chemical or physical variable(s) differ significantly from that found in habitats that support plant and animal life. Topics include using new molecular techniques to discover more about bacteria; life at high temperatures, low temperatures, extreme pH levels and in a brine; and extremophiles in the evolution of life.

Madigan, Michael T.

2010-03-08

287

F-LE Bacteria Populations  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: A hospital is conducting a study to see how different environmental conditions influence the growth of streptococcus pneumonia, one of the bacteria whi...

288

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

289

Anaerobic bacteria from hypersaline environments.  

PubMed

Strictly anaerobic halophiles, namely fermentative, sulfate-reducing, homoacetogenic, phototrophic, and methanogenic bacteria are involved in the oxidation of organic carbon in hypersaline environments. To date, six anaerobic fermentative genera, containing nine species, have been described. Two of them are homoacetogens. Six species belong to the family Haloanaerobiaceae, as indicated by their unique 16S rRNA oligonucleotide sequences. Desulfohalobium retbaense and Desulfovibrio halophilus represent the only two moderately halophilic sulfate reducers so far reported. Among anoxygenic phototrophic anaerobes, a few purple bacteria with optimal growth at salinities between 6 and 11% NaCl have been isolated from hypersaline habitats. They belong to the genera Rhodospirillum, Chromatium, Thiocapsa, and Ectothiorhodospira. The commonest organisms isolated so far are Chromatium salexigens, Thiocapsa halophila, and Rhodospirillum salinarum. Extremely halophilic purple bacteria have most commonly been isolated from alkaline brines and require about 20 to 25% NaCl for optimal growth. They belong to the family Ectothiorodhospiraceae. Their osmoregulation involves synthesis or uptake of compatible solutes such as glycine-betaine that accumulate in their cytoplasm. The existence of methanogens in hypersaline environments is related to the presence of noncompetitive substrates such as methylamines, which originate mainly from the breakdown of osmoregulatory amines. Methanogenesis probably does not contribute to the mineralization of carbohydrates at NaCl concentrations higher than 15%. Above this concentration, sulfate reduction is probably the main way to oxidize H2 (although at rates too low to use up all the H2 formed) and occupies a terminal function kn the degradation of carbohydrates. Three genera and five species of halophilic methylotrophic methanogens have been reported. A bloom of phototrophic bacteria in the marine salterns of Salins-de-Giraud, located on the Mediterranean French coast in the Rhone Delta, is also described. PMID:8177169

Ollivier, B; Caumette, P; Garcia, J L; Mah, R A

1994-03-01

290

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

291

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

292

Dispersal dynamics of groundwater bacteria.  

PubMed

Dispersal of bacteria in saturated, porous soils can be characterized by the partitioning of cells between the aqueous and solid phases, as a result of the physical and chemical nature of the soil and water and cell surface modifications. The purpose of this work is to understand variations in partitioning as a consequence of the nutrient conditions and to use this information in mathematical models to predict the dispersal rate of bacteria in aquifer material. Two different models were used to describe dispersal: an advective-dispersive-sorptive model with a first order kinetic sink term to account for irreversible cell reactions, such as death and sorption; and a two-site reaction model, in which the retardation was assumed to be determined by two types of sites, one characterized by instantaneous equilibrium sorption reactions and the other by kinetic nonequilibrium reactions. Water-saturated sand columns were used as continuous-flow groundwater microcosms to test the models under different nutrient regimes. Two strains of indigenous groundwater bacteria were isolated from aquifer material and labelled with(3)H-alanine,(14)C-pyruvic acid,(3)H-glucose, and(3)H-adenosine for different measurements of sorption and dispersal, which were estimated from breakthrough curves. Both experimental data and model variables showed that dispersal of bacteria was a dynamic nonequilibrium process, possibly shaped by two subpopulations, one strongly, even irreversibly, adsorbing to the solid particles, and one with very slow adsorption kinetics. The cell surfaces were modified in response to the growth conditions, which was demonstrated by hydrophobic and electrostatic interaction chromatography. Cell surface hydrophobicity was about eight times higher in groundwater than in eutrophic lake water. The partition coefficient varied between 12.6 in the groundwater and 6.4 in the lake water, indicating the prime importance of hydrophobic binding for attachment in low nutrient conditions. The partitioning was also sensitive to the hydrodynamics of the system and the oxygen supply, as demonstrated by comparison of sorption in agitated test tubes, gently shaken vials, and air-flushed bottles. Sorption kinetics were demonstrated in a continuous flow cell. About 45% of a population was associated with sand particles with a continuous flow of pure groundwater and as little as 20% in lake water. However, more than 50% of the bacteria in the aqueous phase were associated with suspended material of less than 60 ?m in diameter. This association may enhance dispersal for example, by size exclusion of the colloidal material in the interstitial pores. PMID:24194201

Lindqvist, R; Bengtsson, G

1991-12-01

293

[Utility of the L-alanine-aminopeptidase test for differentiating the cell wall structure of bacteria].  

PubMed

Evaluation of a detection test for L-alanine-aminopeptidase enzyme (Bactident Aminopeptidase) for determining the structure of bacterial cell wall. In a total of 246 clinical isolates of aerobic, microaerophilic and anaerobic bacteria, we detect the presence or absence of L-alanine-aminopeptidase using commercial kits (Bactident Aminopeptidase, Merck Diagnostica). We also identify and further classified the 246 strains. In nearly all gram-negative bacteria L-alanine-aminopeptidase was found, with the exception of Campylobacter spp and gram-negative anaerobic bacilli. All gram-positive and gram-variable bacteria were negative for the L-alanine-aminopeptidase presence. The results suggest a good correlation between the presence or absence of L-alanine-aminopeptidase and Gram stain method. PMID:1726575

Hernández Molina, J M; Martínez, A; Parra, M C; Ortega, M I

1991-12-01

294

Chromosome dynamics in multichromosome bacteria.  

PubMed

On the basis of limited information, bacteria were once assumed to have no more than one chromosome. In the era of genomics, it has become clear that some, like eukaryotes, have more than one chromosome. Multichromosome bacteria provide opportunities to investigate how split genomes emerged, whether the individual chromosomes communicate to coordinate their replication and segregation, and what selective advantages split genomes might provide. Our current knowledge of these topics comes mostly from studies in Vibrio cholerae, which has two chromosomes, chr1 and chr2. Chr1 carries out most of the house-keeping functions and is considered the main chromosome, whereas chr2 appears to have originated from a plasmid and has acquired genes of mostly unknown origin and function. Nevertheless, unlike plasmids, chr2 replicates once and only once per cell cycle, like a bona fide chromosome. The two chromosomes replicate and segregate using separate programs, unlike eukaryotic chromosomes. They terminate replication synchronously, suggesting that there might be communication between them. Replication of the chromosomes is affected by segregation genes but in a chromosome specific fashion, a new development in the field of DNA replication control. The split genome allows genome duplication to complete in less time and with fewer replication forks, which could be beneficial for genome maintenance during rapid growth, which is the norm for V. cholerae in broth cultures and in the human host. In the latter, the expression of chr2 genes increases preferentially. Studies of chromosome maintenance in multichromosomal bacteria, although in their infancy, are already broadening our view of chromosome biology. This article is part of a Special Issue entitled: Chromatin in time and space. PMID:22306663

Jha, Jyoti K; Baek, Jong Hwan; Venkova-Canova, Tatiana; Chattoraj, Dhruba K

2012-07-01

295

[The pleiotropic function of the phosphoenolpyruvate-dependent phosphotransferase system in bacteria. Communication II].  

PubMed

The structure and function of regulators and anti-terminators is under discussion in gram-positive bacteria. The regulators of lichen and levan operons (LiR and LevR) as well as the implementation of both gram-positive and negative regulations of operons by them are in the focus of attention. Po-independent termination is regarded by the example of the regulatory activity for the utilization systems of glucose (GlcT) beta-glucosides (LicT), sucrose (low-efficiency system SacY-SacX) and of glycerin (GlcP). Changes in the functional activity of the above systems, which are dependent on a condition of anti-terminators (phosphorylated or dephosphorylated forms and an ability to demirelize etc.) are regarded from the viewpoint of a possibility of occurrence of catabolic repression. PMID:12966919

Gershanovich, V N

2003-01-01

296

Genetics of acidophilic, heterotrophic bacteria  

SciTech Connect

The genetic characteristics of members of the genus Acidiphilium are poorly understood. As part of our study of the genetics of these bacteria, a search was made for an inducible, lysogenic bacteriophage. Such a bacteriophage has been discovered. Several properties of the phage have been investigated. The phage has a lambdoid morphology and is somewhat larger than lambda. A variety of factors which affect phage stability have been investigated. The bacteriophage infects several of the strains that have been tested. Study of this bacteriophage should greatly increase our understanding of genetic mechanisms in Acidiphilium. 23 refs., 3 figs., 1 tab.

Ward, T.E.; Bruhn, D.F.; Watkins, C.S.; Rowland, M.L.; Bulmer, D.K.; Winston, V.

1988-01-01

297

Bacteria detection instrument and method  

NASA Technical Reports Server (NTRS)

A method and apparatus for screening a sample fluid for bacterial presence are disclosed wherein the fluid sample is mixed with culture media of sufficient quantity to permit bacterial growth in order to obtain a test solution. The concentration of oxygen dissolved in the test solution is then monitored using the potential difference between a reference electrode and a noble metal electrode which are in contact with the test solution. The change in oxygen concentration which occurs during a period of time as indicated by the electrode potential difference is compared with a detection criterion which exceeds the change which would occur absent bacteria.

Renner, W.; Fealey, R. D. (inventors)

1972-01-01

298

Bacteria and vampirism in cinema.  

PubMed

A vampire is a non-dead and non-alive chimerical creature, which, according to various folklores and popular superstitions, feeds on blood of the living to draw vital force. Vampires do not reproduce by copulation, but by bite. Vampirism is thus similar to a contagious disease contracted by intravascular inoculation with a suspected microbial origin. In several vampire films, two real bacteria were staged, better integrated than others in popular imagination: Yersinia pestis and Treponema pallidum. Bacillus vampiris was created for science-fiction. These films are attempts to better define humans through one of their greatest fears: infectious disease. PMID:23916557

Castel, O; Bourry, A; Thévenot, S; Burucoa, C

2013-09-01

299

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

300

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

301

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

SciTech Connect

Ionizing Radiation (IR) Resistance in Bacteria. Until recently, there have been no clear physiologic predictors of a cell's ability to recover from ionizing radiation (IR) and other DOE-relevant oxidative stress conditions. In general, the most resistant bacteria have been Gram-positive (e.g., Deinococcus, Arthrobacter, Lactobacillus & Enterococcus spp.) and the most sensitive have been Gram-negative (e.g., Pseudomonas, Shewanella & Neisseria spp.). However, there are several reported exceptions to this paradigm, the Gram-negative cyanobacterium Chroococcidiopsis is extremely resistant to IR, whereas the Gram-positive Micrococcus luteus is sensitive. We have identified biomolecular signatures for radiation sensitivity and resistance which are independent of phylogeny, where very high and very low intracellular Mn/Fe concentration ratios correlated with very high and very low resistances, respectively; and restricting Mn(II) in the famously resistant Deinococcus radiodurans sensitized this eubacterium to IR.

Daly, Michael J.

2006-05-01

302

Superoxide dismutase in anaerobic bacteria of clinical significance.  

PubMed Central

Twenty-two anaerobic bacteria isolated from infected sites and normal fecal flora were assayed for superoxide dismutase (SOD). The organisms were also classified according to their oxygen tolerance into aerotolerant, intermediate, and extremely oxygen-sensitive groups. There was a correlation between the enzyme level and the oxygen tolerance, in that the aerotolerant and intermediate organisms had SOD, whereas the extremely oxygen-sensitive isolates had low or undetectable enzyme. Among the oxygen-tolerant organisms, gram-negative bacteria had higher levels of SOD than gram-positive organisms. Oxygen was shown to induce SOD production in a strain of Bacteriodes fragilis grown in minimal medium under continuous-culture conditions. Enzyme levels in this isolate grown under static conditions were lower in minimal medium than in complex medium, indicating that other components in the complex medium were stimulating the production of SOD. Our data suggest that the variation in oxygen tolerance of anaerobes is usually related to their level of SOD. It is postulated that SOD may be a virulence factor that allows pathogenic anaerobes to survive in oxygenated tissues until the proper reduced conditions are established for their growth. PMID:326669

Tally, F P; Goldin, B R; Jacobus, N V; Gorbach, S L

1977-01-01

303

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

304

Money and transmission of bacteria  

PubMed Central

Money is one of the most frequently passed items in the world. The aim of this study was to ascertain the survival status of bacteria including Staphylococcus aureus, Escherichia coli, and Vancomycin- Resistant Enterococci (VRE) on banknotes from different countries and the transmission of bacteria to people who come in contact with the banknotes. The survival rate was highest for the Romanian Leu yielding all three microorganisms used after both three and six hours of drying. Furthermore, the Leu was the only banknote to yield VRE after one day of drying. Other currencies either enabled the survival of Extended-Spectrum Beta-Lactamases (ESBL) and VRE (e.g. Euro), but not of MRSA, or the other way round (e.g. US Dollar). While a variety of factors such as community hygiene levels, people’s behaviour, and antimicrobial resistance rates at community level obviously have influence on the transmission of resistant microorganisms, the type of banknote-paper may be an additional variable to consider. PMID:23985137

2013-01-01

305

Medicinal smoke reduces airborne bacteria.  

PubMed

This study represents a comprehensive analysis and scientific validation of our ancient knowledge about the effect of ethnopharmacological aspects of natural products' smoke for therapy and health care on airborne bacterial composition and dynamics, using the Biolog microplate panels and Microlog database. We have observed that 1h treatment of medicinal smoke emanated by burning wood and a mixture of odoriferous and medicinal herbs (havan sámagri=material used in oblation to fire all over India), on aerial bacterial population caused over 94% reduction of bacterial counts by 60 min and the ability of the smoke to purify or disinfect the air and to make the environment cleaner was maintained up to 24h in the closed room. Absence of pathogenic bacteria Corynebacterium urealyticum, Curtobacterium flaccumfaciens, Enterobacter aerogenes (Klebsiella mobilis), Kocuria rosea, Pseudomonas syringae pv. persicae, Staphylococcus lentus, and Xanthomonas campestris pv. tardicrescens in the open room even after 30 days is indicative of the bactericidal potential of the medicinal smoke treatment. We have demonstrated that using medicinal smoke it is possible to completely eliminate diverse plant and human pathogenic bacteria of the air within confined space. PMID:17913417

Nautiyal, Chandra Shekhar; Chauhan, Puneet Singh; Nene, Yeshwant Laxman

2007-12-01

306

The mycorrhiza helper bacteria revisited.  

PubMed

In natural conditions, mycorrhizal fungi are surrounded by complex microbial communities, which modulate the mycorrhizal symbiosis. Here, the focus is on the so-called mycorrhiza helper bacteria (MHB). This concept is revisited, and the distinction is made between the helper bacteria, which assist mycorrhiza formation, and those that interact positively with the functioning of the symbiosis. After considering some examples of MHB from the literature, the ecological and evolutionary implications of the relationships of MHB with mycorrhizal fungi are discussed. The question of the specificity of the MHB effect is addressed, and an assessment is made of progress in understanding the mechanisms of the MHB effect, which has been made possible through the development of genomics. Finally, clear evidence is presented suggesting that some MHB promote the functioning of the mycorrhizal symbiosis. This is illustrated for three critical functions of practical significance: nutrient mobilization from soil minerals, fixation of atmospheric nitrogen, and protection of plants against root pathogens. The review concludes with discussion of future research priorities regarding the potentially very fruitful concept of MHB. PMID:17803639

Frey-Klett, P; Garbaye, J; Tarkka, M

2007-01-01

307

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

308

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

309

Comparative antimicrobial susceptibility of aerobic and facultative bacteria from community-acquired bacteremia to ertapenem in Taiwan  

Microsoft Academic Search

BACKGROUND: Ertapenem is a once-a-day carbapenem and has excellent activity against many gram-positive and gram-negative aerobic, facultative, and anaerobic bacteria. The susceptibility of isolates of community-acquired bacteremia to ertapenem has not been reported yet. The present study assesses the in vitro activity of ertapenem against aerobic and facultative bacterial pathogens isolated from patients with community-acquired bacteremia by determining and comparing

Sai-Cheong Lee; Shie-Shian Huang; Chao-Wei Lee; Ning Lee; Wen-Bin Shieh; LK Siu

2007-01-01

310

Phylogenetic profiling of culturable bacteria associated with early phase of mushroom composting assessed by amplified rDNA restriction analysis  

Microsoft Academic Search

The edible mushroom Agaricus bisporus is grown commercially on composted manure\\/straw mixtures. Mushroom composting is a fermentation process in which various\\u000a groups of microorganisms play important roles at different stages of composting. The present study was conducted to explore\\u000a the mesophilic bacterial diversity in the early phase of mushroom composting. Morphologically all the isolated bacteria were\\u000a either Gram-positive rods, cocci

Ajay Veer Singh; Abhinay Sharma; Bhavdish N. Johri

311

5, 317359, 2008 Bacteria dynamics in  

E-print Network

BGD 5, 317­359, 2008 Bacteria dynamics in mesocosms with increased pCO2 M. Allgaier et al. Title of heterotrophic bacteria to phytoplankton bloom development at different pCO2 levels: a mesocosm study M. Allgaier@igb-berlin.de) 317 #12;BGD 5, 317­359, 2008 Bacteria dynamics in mesocosms with increased pCO2 M. Allgaier et al

Paris-Sud XI, Université de

312

Generating and Exploiting Polarity in Bacteria  

NSDL National Science Digital Library

Bacteria are often highly polarized, exhibiting specialized structures at or near the ends of the cell. Among such structures are actin-organizing centers, which mediate the movement of certain pathogenic bacteria within the cytoplasm of an animal host cell; organized arrays of membrane receptors, which govern chemosensory behavior in swimming bacteria; and asymmetrically positioned septa, which generate specialized progeny in differentiating bacteria. This polarization is orchestrated by complex and dynamic changes in the subcellular localization of signal transduction and cytoskeleton proteins as well as of specific regions of the chromosome. Recent work has provided information on how dynamic subcellular localization occurs and how it is exploited by the bacterial cell.

Lucy Shapiro (Stanford University School of Medicine;Department of Developmental Biology); Harley McAdams (Stanford University School of Medicine;Department of Developmental Biology); Richard Losick (Harvard University;Department of Molecular and Cellular Biology)

2002-12-06

313

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

314

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

315

Coryneform bacteria associated with canine otitis externa.  

PubMed

This study aims to investigate the occurrence of coryneform bacteria in canine otitis externa. A combined case series and case-control study was carried out to improve the current knowledge on frequency and clinical significance of coryneform bacteria in samples from canine otitis externa. A total of 16 cases of otitis externa with involvement of coryneform bacteria were recorded at two referral veterinary hospitals in Denmark and the US, respectively. Coryneform bacteria were identified by partial 16S rRNA gene sequencing. Corynebacterium auriscanis was the most common coryneform species (10 cases). Small colony variants of this species were also observed. Other coryneform isolates were identified as Corynebacterium amycolatum (3 cases), Corynebacterium freneyi (2 cases) and an Arcanobacterium-like species (1 case). The coryneform bacteria were in all cases isolated together with other bacteria, mainly Staphylococcus pseudintermedius alone (n=5) or in combination with Malassezia pachydermatis (n=5). Some coryneform isolates displayed resistance to fusidic acid or enrofloxacin, two antimicrobial agents commonly used for the treatment of otitis externa in dogs. The frequency of isolation of coryneform bacteria was 16% among 55 cases of canine otitis externa examined at the Danish hospital during 2007. In contrast, detectable levels of coryneform bacteria were not demonstrated in samples from the acustic meatus of 35 dogs with apparently healthy ears, attending the hospital during the same year. On basis of the current knowledge, these coryneform bacteria should be regarded as potential secondary pathogens able to proliferate in the environment of an inflamed ear canal. PMID:20434850

Aalbæk, Bent; Bemis, David A; Schjærff, Mette; Kania, Stephen A; Frank, Linda A; Guardabassi, Luca

2010-10-26

316

Managing Bacteria Pollution in Texas Waters  

E-print Network

Story by Kathy Wythe tx H2O | pg. 2 BACTERIA MANAGING tx H2O | pg. 3 IN TEXAS WATERS POLLUTION Managing Bacteria Pollution in Texas Waters tx H2O | pg. 4 W ith 310 water bodies in Texas failing to meetwater quality standards because... of bacteria,managing bacteria pollution is commanding the attention of water agencies, researchers and stake- holders across Texas. These water bodies are listed in the 2006 Texas Water Quality Inventory and 303(d) List for failing to meet the standards...

Wythe, Kathy

2007-01-01

317

Common Virulence Factors and Tissue Targets of Entomopathogenic Bacteria for Biological Control of Lepidopteran Pests  

PubMed Central

This review focuses on common insecticidal virulence factors from entomopathogenic bacteria with special emphasis on two insect pathogenic bacteria Photorhabdus (Proteobacteria: Enterobacteriaceae) and Bacillus (Firmicutes: Bacillaceae). Insect pathogenic bacteria of diverse taxonomic groups and phylogenetic origin have been shown to have striking similarities in the virulence factors they produce. It has been suggested that the detection of phage elements surrounding toxin genes, horizontal and lateral gene transfer events, and plasmid shuffling occurrences may be some of the reasons that virulence factor genes have so many analogs throughout the bacterial kingdom. Comparison of virulence factors of Photorhabdus, and Bacillus, two bacteria with dissimilar life styles opens the possibility of re-examining newly discovered toxins for novel tissue targets. For example, nematodes residing in the hemolymph may release bacteria with virulence factors targeting neurons or neuromuscular junctions. The first section of this review focuses on toxins and their context in agriculture. The second describes the mode of action of toxins from common entomopathogens and the third draws comparisons between Gram positive and Gram negative bacteria. The fourth section reviews the implications of the nervous system in biocontrol. PMID:24634779

Castagnola, Anaïs; Stock, S. Patricia

2014-01-01

318

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

319

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, Vânia L.; Fontes, Cláudia Oliveira; Souza-Filho, Job Alves; de Oliveira, Tamara Lopes Rocha; Coelho, Cíntia Marques; César, Dionéia Evangelista; Diniz, Cláudio Galuppo

2012-01-01

320

Time-resolved and steady-state fluorescence spectroscopy from bacteria subjected to bactericidal agents  

NASA Astrophysics Data System (ADS)

The time-resolved and steady-state changes in fluorescence were investigated from one spore-forming (Bacillus subtilis) and four non-spore forming (Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, and Pseudomonas aeruginosa) bacteria subjected to different bactericidal agents. The bactericidal agents were sodium hypochlorite (bleach) hydrogen peroxide, formaldehyde, and UV light exposure. Application of sodium hypochlorite resulted in an almost total lose of fluorescence signal and large decrease in the optical density of the bacterial suspension. Addition of hydrogen peroxide resulted in a 35% decrease in emission intensity fom the Sa and an 85-95% decrease for the other bacteria. Ultraviolet light exposure resulted in a 5-35% decrease in the emission intensity of the tryptophan band. The addition of formaldehyde to the bacteria did not result in significant changes in the steady-state emission intensity, but did shift the tryptophan emission peak position to shorter wavelengths by 3 to 5 nm. Time-resolved fluorescence measurements showed that the fluorescence lifetime of tryptophan in the bacteria could not be described by a single exponential decay, and was similar to that of tryptophan in neutral aqueous solution. Upon addition of formaldehyde to the Gram positive bacteria (Bs and Sa) the strength of the short lifetime component increased dramatically, while for the Gram negative bacteria, a smaller increase was observed. These fluorescence changes reflect the different mechanisms of the bactericidal agents and may provide a useful tool to monitor the effectiveness of disinfectants.

Katz, Alvin; Alimova, Alexandra; Siddique, Masood; Savage, Howard E.; Shah, Mahendra; Rosen, Richard; Alfano, Robert

2004-03-01

321

Antimicrobial activities of novel cultivable bacteria isolated from marine sponge Tedania anhelans  

NASA Astrophysics Data System (ADS)

Marine sponge Tedania anhelans distributes throughout the intertidal zone of Fujian, southeastern China, and is a potential source of natural bioactive products. The sponge harbors a large number of bacterial groups that have been identified using various techniques, including fluorescent in situ hybridization (FISH). Fractionation of dissociated sponge allowed isolation of 25 bacterial species. Based on 16S rRNA gene sequencing, phylogenetic analysis attributed most of these eubacteria to ?- Proteobacteria, ?- Proteobacteria, Cytophaga / Flavobacterium / Bacteroidetes (CFB group), and the family Bacillaceae of Gram-positive bacteria. In sequence similarity, five putatively novel species were identified with less than 98% similarity to other strains in the NCBI database. Tests for antimicrobial activities were performed against Gram-positive bacteria, Gram-negative bacteria, fungi, antitumor indicators Escherichia coli 343/591 (with DNA repair deficiency), regular E. coli 343/636 (with different DNA repair capacity), and 10 bacterial isolates exhibited inhibitory bioactivities. Among these strains, three isolates were detected involving function gene NRPS-A domains, which were most closely related to the amino acid sequences of linear gramicidin synthetase and pyoverdine synthetase. These results contribute to our knowledge of the microbes associated with marine sponges and further reveal novel bacterial resources for the screening of bioactive marine natural products.

Zeng, Zhen; Zhao, Jing; Ke, Caihuan; Wang, Dexiang

2013-05-01

322

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

PubMed

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 metabolism and transport genes are predicted to be regulated by transcriptional attenuation, whereas in most Gram-negative bacteria, the riboflavin biosynthesis genes seem to be regulated on the level of translation initiation. Several new candidate riboflavin transporters were identified (impX in Desulfitobacterium halfniense and Fusobacterium nucleatum; pnuX in several actinomycetes, including some Corynebacterium species and Strepto myces coelicolor; rfnT in Rhizobiaceae). Traces of a number of likely horizontal transfer events were found: the complete riboflavin operon with the upstream regulatory element was transferred to Haemophilus influenzae and Actinobacillus pleuropneumoniae from some Gram-positive bacterium; non-regulated riboflavin operon in Pyrococcus furiousus was likely transferred from Thermotoga; and the RFN element was inserted into the riboflavin operon of Pseudomonas aeruginosa from some other Pseudomonas species, where it had regulated the ribH2 gene. PMID:12136096

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

2002-07-15

323

Regulation of lysine biosynthesis and transport genes in bacteria: yet another RNA riboswitch?  

PubMed

Comparative analysis of genes, operons and regulatory elements was applied to the lysine biosynthetic pathway in available bacterial genomes. We report identification of a lysine-specific RNA element, named the LYS element, in the regulatory regions of bacterial genes involved in biosynthesis and transport of lysine. Similarly to the previously described RNA regulatory elements for three vitamins (riboflavin, thiamin and cobalamin), purine and methionine regulons, this regulatory RNA structure is highly conserved on the sequence and structural levels. The LYS element includes regions of lysine-constitutive mutations previously identified in Escherichia coli and Bacillus subtilis. A possible mechanism of the lysine-specific riboswitch is similar to the previously defined mechanisms for the other metabolite-specific riboswitches and involves either transcriptional or translational attenuation in various groups of bacteria. Identification of LYS elements in Gram-negative gamma-proteobacteria, Gram-positive bacteria from the Bacillus/Clostridium group, and Thermotogales resulted in description of the previously uncharacterized lysine regulon in these bacterial species. Positional analysis of LYS elements led to identification of a number of new candidate lysine transporters, namely LysW, YvsH and LysXY. Finally, the most likely candidates for genes of lysine biosynthesis missing in Gram- positive bacteria were identified using the genome context analysis. PMID:14627808

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

2003-12-01

324

Occurrence of mazEF-like antitoxin/toxin systems in bacteria.  

PubMed

The mazEF locus of Escherichia coil located in an operon together with the upstream relA gene (encoding ATP:GTP 3'-pyrophosphotransferase; (p)ppGpp synthetase), encodes an antitoxin/toxin system which might play a role in programmed cell death under stress and starvation conditions at high cell densities. By homology searches, chromosomally encoded orthologous systems were identified in a variety of bacteria, sometimes without the MazE-like antitoxin, and several bacterial species possess multiple MazEF-like systems (paralogs). In many gram positive bacteria, the mazEF-locus is located directly upstream of the sigB (stress sigma factor sigmaB) operon in a putative operon together with the upstream dal (aIr) gene (encoding D-alanine racemase). The acidic antitoxins are less conserved than the basic toxins. The differences in genomic organization of the mazEFloci in E. coli versus those in gram positive bacteria might indicate their association with different stress response regulons in these organisms. A study on the sigmaB operon of Staphylococcus aureus showed that the mazF gene of this organism is cotranscribed with the sigmaB operon in response to heat shock, providing the first example that the expression of the mazEFlocus might be indeed associated with stress responses. PMID:10943559

Mittenhuber, G

1999-11-01

325

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

326

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

327

Beating bacteria: Scientists work to understand and track bacteria in water  

E-print Network

tx H2O | pg. 11 Story by Kathy Wythe Bacteria Task Force Recommendations Acknowledging the enormity of the bacteria problem within the state, in September 2006, TCEQ and the Texas State Soil and Water Conservation Board (TSSWCB...) established a joint Task Force on Bacteria Total Maximum Daily Loads (TMDLs) to make recommenda- tions to strengthen the agencies? efforts in cleaning up bacteria- contaminated waters. Dr. Allan Jones, formerly of the Texas Water Resources Institute...

Wythe, Kathy

2010-01-01

328

[Surface layers of methanotrophic bacteria].  

PubMed

Structural and functional characteristics of the regular glycoprotein layers in prokaryotes are analyzed with a special emphasis on aerobic methanotrophic bacteria. S-layers are present at the surfaces of Methylococcus, Methylothermus, and Methylomicrobium cells. Different Methylomicrobium species either synthesize S-layers with planar (p2, p4) symmetry or form cup-shaped or conicalstructures with hexagonal (p6) symmetry. A unique, copper-binding polypeptide 'CorA'/MopE (27/45 kDa), which is coexpressed with the diheme periplasmic cytochrome c peroxidase 'CorB'/Mca (80 kDa) was found in Methylomicrobium album BG8, Methylomicrobium alcaliphilum 20Z, and Methylococcus capsulatus Bath. This tandem of the surface proteins is functionally analogous to a new siderophore, methanobactin. Importantly, no 'CorA'/MopE homologue was found in methanotrophs not forming S-layers. The role of surface proteins in copper metabolism and initial methane oxidation is discussed. PMID:25509389

Khmelenina, V N; Suzina, N E; Trotsenko, Iu A

2013-01-01

329

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

330

Antibiotic Killing of Bacteria: Comparison of Bacteria on Surfaces and in Liquid, Growing and Nongrowing  

Microsoft Academic Search

The minimum inhibitory concentrations of antibiotics for bacterial pathogens are derived from broth suspensions (broth dilution) and from nutrient surfaces (agar dilution). These concentrations may not apply when bacteria are on a nonnutrient surface such as in a foreign body infection. We compared bacteria (Staphylococcus epidermidis and Escherichia coli)broth suspension MBCs with MBCs of the same bacteria when on a

Robert H. K. Eng; Anita Hsieh; Sharon M. Smith

1995-01-01

331

Genetic diversity of siderophore-producing bacteria of tobacco rhizosphere.  

PubMed

The genetic diversity of siderophore-producing bacteria of tobacco rhizosphere was studied by amplified ribosomal DNA restriction analysis (ARDRA), 16S rRNA sequence homology and phylogenetics analysis methods. Studies demonstrated that 85% of the total 354 isolates produced siderophores in iron limited liquid medium. A total of 28 ARDRA patterns were identified among the 299 siderophore-producing bacterial isolates. The 28 ARDRA patterns represented bacteria of 14 different genera belonging to six bacterial divisions, namely ?-, ?-, ?-Proteobacteria, Sphingobacteria, Bacilli, and Actinobacteria. Especially, ?-Proteobacteria consisting of Pseudomonas, Enterobacter, Serratia, Pantoea, Erwinia and Stenotrophomonas genus encountered 18 different ARDRA groups. Results also showed a greater siderophore-producing bacterial diversity than previous researches. For example, Sphingobacterium (isolates G-2-21-1 and G-2-27-2), Pseudomonas poae (isolate G-2-1-1), Enterobacter endosymbiont (isolates G-2-10-2 and N-5-10), Delftia acidovorans (isolate G-1-15), and Achromobacter xylosoxidans (isolates N-46-11HH and N-5-20) were reported to be able to produce siderophores under low-iron conditions for the first time. Gram-negative isolates were more frequently encountered, with more than 95% total frequency. For Gram-positive bacteria, the Bacillus and Rhodococcus were the only two genera, with 1.7% total frequency. Furthermore, the Pseudomonas and Enterobacter were dominant in this environment, with 44.5% and 24.7% total frequency, respectively. It was also found that 75 percent of the isolates that had the high percentages of siderophore units (% between 40 and 60) belonged to Pseudomonas. Pseudomonas sp. G-229-21 screened out in this study may have potential to apply to low-iron soil to prevent plant soil-borne fungal pathogen diseases. PMID:24031358

Tian, Fang; Ding, Yanqin; Zhu, Hui; Yao, Liangtong; Du, Binghai

2009-04-01

332

Genetic diversity of siderophore-producing bacteria of tobacco rhizosphere  

PubMed Central

The genetic diversity of siderophore-producing bacteria of tobacco rhizosphere was studied by amplified ribosomal DNA restriction analysis (ARDRA), 16S rRNA sequence homology and phylogenetics analysis methods. Studies demonstrated that 85% of the total 354 isolates produced siderophores in iron limited liquid medium. A total of 28 ARDRA patterns were identified among the 299 siderophore-producing bacterial isolates. The 28 ARDRA patterns represented bacteria of 14 different genera belonging to six bacterial divisions, namely ?-, ?-, ?-Proteobacteria, Sphingobacteria, Bacilli, and Actinobacteria. Especially, ?-Proteobacteria consisting of Pseudomonas, Enterobacter, Serratia, Pantoea, Erwinia and Stenotrophomonas genus encountered 18 different ARDRA groups. Results also showed a greater siderophore-producing bacterial diversity than previous researches. For example, Sphingobacterium (isolates G-2-21-1 and G-2-27-2), Pseudomonas poae (isolate G-2-1-1), Enterobacter endosymbiont (isolates G-2-10-2 and N-5-10), Delftia acidovorans (isolate G-1-15), and Achromobacter xylosoxidans (isolates N-46-11HH and N-5-20) were reported to be able to produce siderophores under low-iron conditions for the first time. Gram-negative isolates were more frequently encountered, with more than 95% total frequency. For Gram-positive bacteria, the Bacillus and Rhodococcus were the only two genera, with 1.7% total frequency. Furthermore, the Pseudomonas and Enterobacter were dominant in this environment, with 44.5% and 24.7% total frequency, respectively. It was also found that 75 percent of the isolates that had the high percentages of siderophore units (% between 40 and 60) belonged to Pseudomonas. Pseudomonas sp. G-229-21 screened out in this study may have potential to apply to low-iron soil to prevent plant soil-borne fungal pathogen diseases. PMID:24031358

Tian, Fang; Ding, Yanqin; Zhu, Hui; Yao, Liangtong; Du, Binghai

2009-01-01

333

Bacteria causing ventriculoperitoneal shunt infections in a Kenyan population.  

PubMed

OBJECT Ventriculoperitoneal shunt (VPS) infections are a major cause of morbidity and mortality in patients with hydrocephalus. Most data about these infections come from the Western literature. Few data about infecting organisms in Africa are available, yet knowledge of these organisms is important for the prevention and treatment of infectious complications. The purpose of this study was to determine the organisms cultured from infected shunts in a rural Kenyan hospital. METHODS The authors conducted a retrospective study of patients with VPS infections recorded in the neurosurgical database of BethanyKids at Kijabe Hospital between September 2010 and July 2012. RESULTS Among 53 VPS infections confirmed by culture, 68% occurred in patients who were younger than 6 months. Seventy-nine percent of the infections occurred within 2 months after shunt insertion. Only 51% of infections were caused by Staphylococcus species (Staphylococcus aureus 25%, other Staphylococcus species 26%), whereas 40% were caused by gram-negative bacteria. All S. aureus infections and 79% of other Staphylococcus infections were sensitive to cefazolin, but only 1 of 21 gram-negative bacteria was sensitive to it. The majority of gram-negative bacterial infections were multidrug resistant, but 17 of the 20 gram-negative bacteria were sensitive to meropenem. Gram-negative bacterial infections were associated with worse outcomes. CONCLUSIONS The high proportion of gram-negative infections differs from data in the Western literature, in which Staphylococcus epidermidis is by far the most common organism. Once a patient is diagnosed with a VPS infection in Kenya, immediate treatment is recommended to cover both gram-positive and gram-negative bacterial infections. Data from other Sub-Saharan countries are needed to determine if those countries have the same increased frequency of gram-negative infections. PMID:25431903

Ochieng', Naomi; Okechi, Humphrey; Ferson, Susan; Albright, A Leland

2014-11-28

334

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

335

An overview of the alpha-, beta- and gamma-carbonic anhydrases from Bacteria: can bacterial carbonic anhydrases shed new light on evolution of bacteria?  

PubMed

Abstract Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes which catalyze a simple but physiologically crucial reaction in all life Domains, the carbon dioxide hydration to bicarbonate and protons: CO2?+?H2O ? [Formula: see text](?)+?H(+). These enzymes are involved in many physiologic processes, such as photosynthesis, respiration, CO2 transport, as well as metabolism of xenobiotics. Five different, genetically distinct CA families are known to date: the ?-, ?-, ?-, ?- and ?-CAs. ?-, ?- and ?-CAs use Zn(II) ions at the active site, the ?-CAs are probably Fe(II) enzymes (but they are active also with bound Zn(II) or Co(II) ions), whereas the ?-class uses Cd(II) or Zn(II) to perform the physiologic reaction catalysis. Bacteria encode for enzymes belonging to the ?-, ?-, and ?-CA classes. They contain zinc ion (Zn(2+)) in their active site, coordinated by three histidine residues and a water molecule/hydroxide ion (in the ? and ?) or by two cysteine and one histidine residues (in the ? class), with the fourth ligand being a water molecule/hydroxide ion. Here we propose that bacterial CAs can be used as markers for understanding the evolution and genetic variability of the Gram-positive and Gram-negative bacteria. We addressed several questions such as: (1) why are ?-CAs present only in the genome of Gram-negative bacteria; (2) why are ?-CAs not present in all Gram-negative bacteria; (3) why do Bacteria show an intricate pattern of CA gene expression; (4) what are the physiologic roles of such diverse CAs in these prokaryotes. We proposed possible answers to the previous questions. Moreover, we speculated on the evolution of the CA classes (?, ? and ?) identified in the Gram-negative and -positive bacteria. Our main hypothesis is that from the ancestral Ur-CA, the ?-class arose first, followed by the ?-class; the ?-class CAs came last it is found only in the Gram-negative bacteria. PMID:24766661

Capasso, Clemente; Supuran, Claudiu T

2014-04-25

336

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

337

Bacteria are like Popeye the sailor man  

NSDL National Science Digital Library

Popeye the sailor man and infection-causing bacteria have something in common -- they need to consume iron to perform their best. In cartoons, Popeye gets his iron from spinach. New research shows exactly where the bacteria that often cause pneumonia get their iron.

American Association for the Advancement of Science (AAAS; )

2004-09-10

338

Immunology Taught by Bacteria Russell E. Vance  

E-print Network

Immunology Taught by Bacteria Russell E. Vance Received: 11 March 2010 /Accepted: 12 March 2010 multiple pathogenic bacteria. Conclusion Thus, immunology taught by L. pneumophila may lead to a more "Immunology Taught by Viruses" [1]. Zinkerna- gel's message was targeted to a generation of immunolo- gists

Vance,. Russell

339

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

340

Monitoring of environmental pollutants by bioluminescent bacteria  

Microsoft Academic Search

This review deals with the applications of bioluminescent bacteria to the environmental analyses, published during the years 2000–2007. The ecotoxicological assessment, by bioassays, of the environmental risks and the luminescent approaches are reported. The review includes a brief introduction to the characteristics and applications of bioassays, a description of the characteristics and applications of natural bioluminescent bacteria (BLB), and a

Stefano Girotti; Elida Nora Ferri; Maria Grazia Fumo; Elisabetta Maiolini

2008-01-01

341

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

342

Amino acid dehydrogenases from thermotolerant bacteria  

Microsoft Academic Search

We isolated many thermotolerant bacteria from soil samples and selected the bacteria, which showed phenylalanine dehydrogenase and lysine dehydrogenase activities. Phenylalanine dehydrogenase can be useful for the enzymatic syntheses of L-phenylalanine and its derivatives and for the enzymatic assay of phenylketoneurea syndrome. Lysine dehydrogenase is useful for the enzymatic syntheses of L-?- aminoadipate, which is a useful material for the

Kanoktip PACKDIBAMRUNG; Siriporn SITTIPRANEED; Shinji NAGATA; Haruo MISONO

343

Comparative genomics of the lactic acid bacteria  

Technology Transfer Automated Retrieval System (TEKTRAN)

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 bacter...

344

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

345

Method of dispersing a hydrocarbon using bacteria  

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, Richard L. (Clinton, TN)

1996-01-01

346

Systemic resistance induced by rhizosphere bacteria  

Microsoft Academic Search

Nonpathogenic rhizobacteria can induce a systemic resistance in plants that is phenotypically similar to pathogen-induced systemic acquired resistance (SAR). Rhizobacteria-mediated induced systemic resistance (ISR) has been demonstrated against fungi, bacteria, and viruses in Arabidopsis, bean, carnation, cucumber, radish, tobacco, and tomato under conditions in which the inducing bacteria and the challenging pathogen remained spatially separated. Bacterial strains differ in their

L. C. van Loon; P. A. H. M. Bakker; C. M. J. Pieterse

1998-01-01

347

Bacteria-based communication in nanonetworks  

Microsoft Academic Search

This paper describes a Bacteria-based Nanonetwork for communication between eukaryotic cell sized nano devices. The communication is achieved by the exchange of DNA molecules which are transported by bacteria guided by chemotaxis. First, the modules of the network are described and all the biological phenomena that support the basic communication steps are explained in detail. Then an analytical model is

Luis C. Cobo; Ian F. Akyildiz

2010-01-01

348

Micromorphology of Gram-negative hydrogen bacteria  

Microsoft Academic Search

The cell morphology, the arrangement and fine structure of flagella and the piliation of the following Gram-negative aerobic hydrogen bacteria have been studied: Alcaligenes eutrophus, Alcaligenes paradoxus, Alcaligenes ruhlandii, Pseudomonas flava, Pseudomonas pseudoflava, Pseudomonas palleronii, Pseudomonas facilis, Aquaspirillum autotrophicum, Paracoccus denitrificans, Corynebacterium autotrophicum, and strains MA 2 and SA 35. The identity of the bacteria was examined by their substrate

M. Aragno; Anna Walther-Mauruschat; F. Mayer; H. G. Schlegel

1977-01-01

349

Comparative electrochemical inactivation of bacteria and bacteriophage  

Microsoft Academic Search

Electric fields and currents have been shown to be capable of disinfecting drinking water and reducing the numbers of bacteria and yeast in food. However, little research has been conducted regarding the effectiveness of electric fields and currents in the inactivation of viruses. The objective of this study was to compare the ability of bacteria and bacteriophage to survive exposure

Kevin P. Drees; Morteza Abbaszadegan; Raina M. Maier

2003-01-01

350

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

351

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

352

Bioactivity determination of methanol and water extracts for roots and leaves of Kenyan Psidium guajava L landraces against pathogenic bacteria.  

PubMed

Guava (Psidium guajava L) is native to South America and exists as both wild and cultivated. Guava has been used as a source of food and raw materials for pharmaceuticals. The aim of this study was to determine bioactivity of methanol and water extracts from root and leaves of Kenyan guava landraces against selected pathogenic bacteria. Study samples were collected from Western and South Coast of Kenya. One hundred grams of leaf and root ground powders were used for sequential extraction using methanol and water. Extracts were evaporated and 0.2gms dissolved using the extraction solvent and tested against gram positive (Staphylococcus aureus, Bacillus subtilis) and negative bacteria (Escherichia coli). Data on inhibition zone was taken in mm and analyzed at 95% confidence interval. Extracts from Western region had significant inhibition compared to Coastal region. The two regions have different climatic conditions that result in these plants having different compounds even though they are the same species. Roots had higher inhibition compared to the leaves as they contain high levels of tannins compared to leaves. Water as an extracting solvent had higher inhibition than methanol as it is more polar and it absorbs more bioactive compounds. S. aureus was most inhibited followed by E. coli and B. subtilis respectively. There was no significant difference between the gram positive and negative bacteria. Remarkably, some methanol and water root extracts had significant inhibition against bacteria when compared to some commercial antibiotics used. Results of this study indicate that Kenyan guava roots from Western Kenya extracted with methanol and water have a potential to be used as a source of active compounds in treatment of gram positive and gram negative bacteria pathogens. PMID:25674419

Liharaka Kidaha, Mercy; Alakonya, Amos Emitati; Nyende, Aggrey Benard

2013-01-01

353

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

PubMed Central

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

354

MRSA, Clostridium difficile and Other Drug Resistant Bacteria Information for Patients and Families What is Drug Resistant Bacteria?  

E-print Network

MRSA, Clostridium difficile and Other Drug Resistant Bacteria Information for Patients and Families What is Drug Resistant Bacteria? Drug Resistant Bacteria also referred to as Multi Drug Resistant Bacteria? Drug Resistant Bacteria are germs that can not be treated by some antibiotics often used to treat

Oliver, Douglas L.

355

NClassG+: A classifier for non-classically secreted Gram-positive bacterial proteins  

PubMed Central

Background Most predictive methods currently available for the identification of protein secretion mechanisms have focused on classically secreted proteins. In fact, only two methods have been reported for predicting non-classically secreted proteins of Gram-positive bacteria. This study describes the implementation of a sequence-based classifier, denoted as NClassG+, for identifying non-classically secreted Gram-positive bacterial proteins. Results Several feature-based classifiers were trained using different sequence transformation vectors (frequencies, dipeptides, physicochemical factors and PSSM) and Support Vector Machines (SVMs) with Linear, Polynomial and Gaussian kernel functions. Nested k-fold cross-validation (CV) was applied to select the best models, using the inner CV loop to tune the model parameters and the outer CV group to compute the error. The parameters and Kernel functions and the combinations between all possible feature vectors were optimized using grid search. Conclusions The final model was tested against an independent set not previously seen by the model, obtaining better predictive performance compared to SecretomeP V2.0 and SecretPV2.0 for the identification of non-classically secreted proteins. NClassG+ is freely available on the web at http://www.biolisi.unal.edu.co/web-servers/nclassgpositive/ PMID:21235786

2011-01-01

356

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

357

Overview of resistant gram-positive pathogens in the surgical patient.  

PubMed

Staphylococci and enterococci are the most common pathogens in surgical-site and bloodstream infections. The emergence of drug resistance among these gram-positive bacteria thus poses a substantial threat to patients with surgical infections. Resistance to methicillin/oxacillin is frequently observed in Staphylococcus aureus isolates and is often accompanied by multidrug resistance. Vancomycin is usually the treatment of choice for infections caused by methicillin-resistant S. aureus (MRSA), so the recent appearance of S. aureus isolated with intermediate sensitivity to vancomycin is cause for concern. Vancomycin resistance has already appeared in most species of enterococci. Infections caused by vancomycin-resistant enterococci (VRE) are associated with increased mortality compared to infections caused by vancomycin-sensitive isolates. Measures for preventing vancomycin resistance include reducing the use of vancomycin and other agents that appear to be associated with VRE, including third-generation cephalosporins and anti-anaerobic drugs. Third-generation cephalosporins have also been implicated in the increased prevalence of MRSA infections. Prudent use of existing antibiotics is an essential strategy for combating the rising tide of drug-resistant gram-positive pathogens. PMID:12594908

Rapp, R P

2000-01-01

358

Top 10 plant pathogenic bacteria in molecular plant pathology.  

E-print Network

G.P.C. (2001) Quorum sensing in Gram-negative bacteria. FEMSQuorum sensing: cell-to-cell communication in bacteria.Quorum sensing, virulence and secondary metabolite production in plant soft rotting bacteria.

2012-01-01

359

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

360

Antibiotic resistance in probiotic bacteria  

PubMed Central

Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. The main probiotic bacteria are strains belonging to the genera Lactobacillus and Bifidobacterium, although other representatives, such as Bacillus or Escherichia coli strains, have also been used. Lactobacillus and Bifidobacterium are two common inhabitants of the human intestinal microbiota. Also, some species are used in food fermentation processes as starters, or as adjunct cultures in the food industry. With some exceptions, antibiotic resistance in these beneficial microbes does not constitute a safety concern in itself, when mutations or intrinsic resistance mechanisms are responsible for the resistance phenotype. In fact, some probiotic strains with intrinsic antibiotic resistance could be useful for restoring the gut microbiota after antibiotic treatment. However, specific antibiotic resistance determinants carried on mobile genetic elements, such as tetracycline resistance genes, are often detected in the typical probiotic genera, and constitute a reservoir of resistance for potential food or gut pathogens, thus representing a serious safety issue. PMID:23882264

Gueimonde, Miguel; Sánchez, Borja; G. de los Reyes-Gavilán, Clara; Margolles, Abelardo

2013-01-01

361

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

362

Are Uncultivated Bacteria Really Uncultivable?  

PubMed Central

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

363

Exogenous Alanine and/or Glucose plus Kanamycin Kills Antibiotic-Resistant Bacteria.  

PubMed

Multidrug-resistant bacteria are an increasingly serious threat to human and animal health. However, novel drugs that can manage infections by multidrug-resistant bacteria have proved elusive. Here we show that glucose and alanine abundances are greatly suppressed in kanamycin-resistant Edwardsiella tarda by GC-MS-based metabolomics. Exogenous alanine or glucose restores susceptibility of multidrug-resistant E. tarda to killing by kanamycin, demonstrating an approach to killing multidrug-resistant bacteria. The mechanism underlying this approach is that exogenous glucose or alanine promotes the TCA cycle by substrate activation, which in turn increases production of NADH and proton motive force and stimulates uptake of antibiotic. Similar results are obtained with other Gram-negative bacteria (Vibrio parahaemolyticus, Klebsiella pneumoniae, Pseudomonas aeruginosa) and Gram-positive bacterium (Staphylococcus aureus), and the results are also reproduced in a mouse model for urinary tract infection. This study establishes a functional metabolomics-based strategy to manage infection by antibiotic-resistant bacteria. PMID:25651179

Peng, Bo; Su, Yu-Bin; Li, Hui; Han, Yi; Guo, Chang; Tian, Yao-Mei; Peng, Xuan-Xian

2015-02-01

364

The antimicrobial activity of lactic acid bacteria from fermented maize (kenkey) and their interactions during fermentation.  

PubMed

A total of 241 lactic acid bacteria belonging to Lactobacillus plantarum, Pediococcus pentosaceus, Lactobacillus fermentum/reuteri and Lactobacillus brevis from various processing stages of maize dough fermentation were investigated. Results indicated that each processing stage has its own microenvironment with strong antimicrobial activity. About half of the Lact. plantarum and practically all of the Lact. fermentum/reuteri investigated were shown to inhibit other Gram-positive and Gram-negative bacteria, explaining the elimination of these organisms during the initial processing stages. Further, widespread microbial interactions amounting to 85% to 18% of all combinations tested were demonstrated amongst lactic acid bacteria within the various processing stages, i.e. raw material, steeping, 0 h and 48 h of fermentation, explaining the microbial succession taking place amongst lactic acid bacteria during fermentation. The antimicrobial effect was explained by the combined effect of acids, compounds sensitive to proteolytic enzymes and other compounds with antimicrobial activity with the acid production being the most important factor. The pattern of antimicrobial factors was not species-specific and the safety and storage stability of fermented maize seem to depend on a mixed population of lactic acid bacteria with different types of antimicrobial characteristics. This means that introduction of pure cultures as starters may impose a risk to the product. PMID:8567490

Olsen, A; Halm, M; Jakobsen, M

1995-11-01

365

The unique regulation of iron-sulfur cluster biogenesis in a Gram-positive bacterium  

PubMed Central

Iron-sulfur clusters function as cofactors of a wide range of proteins, with diverse molecular roles in both prokaryotic and eukaryotic cells. Dedicated machineries assemble the clusters and deliver them to the final acceptor molecules in a tightly regulated process. In the prototypical Gram-negative bacterium Escherichia coli, the two existing iron-sulfur cluster assembly systems, iron-sulfur cluster (ISC) and sulfur assimilation (SUF) pathways, are closely interconnected. The ISC pathway regulator, IscR, is a transcription factor of the helix-turn-helix type that can coordinate a [2Fe-2S] cluster. Redox conditions and iron or sulfur availability modulate the ligation status of the labile IscR cluster, which in turn determines a switch in DNA sequence specificity of the regulator: cluster-containing IscR can bind to a family of gene promoters (type-1) whereas the clusterless form recognizes only a second group of sequences (type-2). However, iron-sulfur cluster biogenesis in Gram-positive bacteria is not so well characterized, and most organisms of this group display only one of the iron-sulfur cluster assembly systems. A notable exception is the unique Gram-positive dissimilatory metal reducing bacterium Thermincola potens, where genes from both systems could be identified, albeit with a diverging organization from that of Gram-negative bacteria. We demonstrated that one of these genes encodes a functional IscR homolog and is likely involved in the regulation of iron-sulfur cluster biogenesis in T. potens. Structural and biochemical characterization of T. potens and E. coli IscR revealed a strikingly similar architecture and unveiled an unforeseen conservation of the unique mechanism of sequence discrimination characteristic of this distinctive group of transcription regulators. PMID:24847070

Santos, Joana A.; Alonso-García, Noelia; Macedo-Ribeiro, Sandra; Pereira, Pedro José Barbosa

2014-01-01

366

Evidence for Direct Electron Transfer by a Gram-Positive Bacterium Isolated from a Microbial Fuel Cell?†  

PubMed Central

Despite their importance in iron redox cycles and bioenergy production, the underlying physiological, genetic, and biochemical mechanisms of extracellular electron transfer by Gram-positive bacteria remain insufficiently understood. In this work, we investigated respiration by Thermincola potens strain JR, a Gram-positive isolate obtained from the anode surface of a microbial fuel cell, using insoluble electron acceptors. We found no evidence that soluble redox-active components were secreted into the surrounding medium on the basis of physiological experiments and cyclic voltammetry measurements. Confocal microscopy revealed highly stratified biofilms in which cells contacting the electrode surface were disproportionately viable relative to the rest of the biofilm. Furthermore, there was no correlation between biofilm thickness and power production, suggesting that cells in contact with the electrode were primarily responsible for current generation. These data, along with cryo-electron microscopy experiments, support contact-dependent electron transfer by T. potens strain JR from the cell membrane across the 37-nm cell envelope to the cell surface. Furthermore, we present physiological and genomic evidence that c-type cytochromes play a role in charge transfer across the Gram-positive bacterial cell envelope during metal reduction. PMID:21908627

Wrighton, K. C.; Thrash, J. C.; Melnyk, R. A.; Bigi, J. P.; Byrne-Bailey, K. G.; Remis, J. P.; Schichnes, D.; Auer, M.; Chang, C. J.; Coates, J. D.

2011-01-01

367

Threats and opportunities of plant pathogenic bacteria.  

PubMed

Plant pathogenic bacteria can have devastating effects on plant productivity and yield. Nevertheless, because these often soil-dwelling bacteria have evolved to interact with eukaryotes, they generally exhibit a strong adaptivity, a versatile metabolism, and ingenious mechanisms tailored to modify the development of their hosts. Consequently, besides being a threat for agricultural practices, phytopathogens may also represent opportunities for plant production or be useful for specific biotechnological applications. Here, we illustrate this idea by reviewing the pathogenic strategies and the (potential) uses of five very different (hemi)biotrophic plant pathogenic bacteria: Agrobacterium tumefaciens, A. rhizogenes, Rhodococcus fascians, scab-inducing Streptomyces spp., and Pseudomonas syringae. PMID:24216222

Tarkowski, Petr; Vereecke, Danny

2014-01-01

368

[Screening of marine bacteria for fucoidan hydrolases].  

PubMed

Twenty-five strains of epiphytic marine bacteria isolated from the brown algae Fucus evanescens and Chorda filum and fifty-three bacteria isolated from the sea cucumber Apostichopus japonicus were screened for fucoidanases using fucoidans prepared from the brown algae F. evanescens, Laminaria cichorioides, and L. japonica. Eighteen bacterial epiphytes and thirty-eight bacterial isolates from the sea cucumber were found to contain fucoidanases, which were able to hydrolyze either all of the fucoidans studied or some of them. Bacteria of the genera Cytophaga and Alteromonas/Pseudoalteromonas exhibited the highest fucoidanase activities, which, however, did not exceed the activity of fucoidanases from the already known sources. PMID:10920807

Bakunina, I Iu; Shevchenko, L S; Nedashkovskaia, O I; Shevchenko, N M; Alekseeva, S A; Mikha?lov, V V; Zviagintseva, T N

2000-01-01

369

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

370

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

371

Community structures of actively growing bacteria shift along a north-south transect in the western North Pacific  

PubMed Central

Bacterial community structures and their activities in the ocean are tightly coupled with organic matter fluxes and thus control ocean biogeochemical cycles. Bromodeoxyuridine (BrdU), halogenated nucleoside and thymidine analogue, has been recently used to monitor actively growing bacteria (AGB) in natural environments. We labelled DNA of proliferating cells in seawater bacterial assemblages with BrdU and determined community structures of the bacteria that were possible key species in mediating biochemical reactions in the ocean. Surface seawater samples were collected along a north-south transect in the North Pacific in October 2003 and subjected to BrdU magnetic beads immunocapture and PCR-DGGE (BUMP-DGGE) analysis. Change of BrdU-incorporated community structures reflected the change of water masses along a north-south transect from subarctic to subtropical gyres in the North Pacific. We identified 25 bands referred to AGB as BrdU-incorporated phylotypes, belonging to Alphaproteobacteria (5 bands), Betaproteobacteria (1 band), Gammaproteobacteria (4 bands), Cytophaga-Flavobacterium-Bacteroides (CFB) group bacteria (5 bands), Gram-positive bacteria (6 bands), and Cyanobacteria (4 bands). BrdU-incorporated phylotypes belonging to Vibrionales, Alteromonadales and Gram-positive bacteria appeared only at sampling stations in a subtropical gyre, while those belonging to Roseobacter-related bacteria and CFB group bacteria appeared at the stations in both subarctic and subtropical gyres. Our result revealed phylogenetic affiliation of AGB and their dynamic change along with north-south environmental gradients in open oceans. Different species of AGB utilize different amount and kinds of substrates, which can affect the change of organic matter fluxes along transect. PMID:18177366

Taniguchi, Akito; Hamasaki, Koji

2008-01-01

372

Evaluation of the in vitro activity of levornidazole, its metabolites and comparators against clinical anaerobic bacteria.  

PubMed

This study evaluated the in vitro anti-anaerobic activity and spectrum of levornidazole, its metabolites and comparators against 375 clinical isolates of anaerobic bacteria, including Gram-negative bacilli (181 strains), Gram-negative cocci (11 strains), Gram-positive bacilli (139 strains) and Gram-positive cocci (44 strains), covering 34 species. Minimum inhibitory concentrations (MICs) of levornidazole, its five metabolites and three comparators against these anaerobic isolates were determined by the agar dilution method. Minimum bactericidal concentrations (MBCs) of levornidazole and metronidazole were measured against 22 strains of Bacteroides fragilis. Levornidazole showed good activity against B. fragilis, other Bacteroides spp., Clostridium difficile, Clostridium perfringens and Peptostreptococcus magnus, evidenced by MIC90 values of 0.5, 1, 0.25, 2 and 1mg/L, respectively. The activity of levornidazole and the comparators was poor for Veillonella spp. Generally, levornidazole displayed activity similar to or slightly higher than that of metronidazole, ornidazole and dextrornidazole against anaerobic Gram-negative bacilli, Gram-positive bacilli and Gram-positive cocci, especially B. fragilis. Favourable anti-anaerobic activity was also seen with levornidazole metabolites M1 and M4 but not M2, M3 or M5. For the 22 clinical B. fragilis strains, MBC50 and MBC90 values of levornidazole were 2mg/L and 4mg/L, respectively. Both MBC50/MIC50 and MBC90/MIC90 ratios of levornidazole were 4, similar to those of metronidazole. Levornidazole is an important anti-anaerobic option in clinical settings in terms of its potent and broad-spectrum in vitro activity, bactericidal property, and the anti-anaerobic activity of its metabolites M1 and M4. PMID:25301712

Hu, Jiali; Zhang, Jing; Wu, Shi; Zhu, Demei; Huang, Haihui; Chen, Yuancheng; Yang, Yang; Zhang, Yingyuan

2014-12-01

373

ADAPTATIONS OF INDIGENOUS BACTERIA TO FUEL CONTAMINATION IN KARST AQUIFERS IN SOUTH-CENTRAL KENTUCKY  

USGS Publications Warehouse

The karst aquifer systems in southern Kentucky can be dynamic and quick to change. Microorganisms that live in these unpredictable aquifers are constantly faced with environmental changes. Their survival depends upon adaptations to changes in water chemistry, taking advantage of positive stimuli and avoiding negative environmental conditions. The U.S. Geological Survey conducted a study in 2001 to determine the capability of bacteria to adapt in two distinct regions of water quality in a karst aquifer, an area of clean, oxygenated groundwater and an area where the groundwater was oxygen depleted and contaminated by jet fuel. Water samples containing bacteria were collected from one clean well and two jet fuel contaminated wells in a conduit-dominated karst aquifer. Bacterial concentrations, enumerated through direct count, ranged from 500,000 to 2.7 million bacteria per mL in the clean portion of the aquifer, and 200,000 to 3.2 million bacteria per mL in the contaminated portion of the aquifer over a twelve month period. Bacteria from the clean well ranged in size from 0.2 to 2.5 mm, whereas bacteria from one fuel-contaminated well were generally larger, ranging in size from 0.2 to 3.9 mm. Also, bacteria collected from the clean well had a higher density and, consequently, were more inclined to sink than bacteria collected from contaminated wells. Bacteria collected from the clean portion of the karst aquifer were predominantly (,95%) Gram-negative and more likely to have flagella present than bacteria collected from the contaminated wells, which included a substantial fraction (,30%) of Gram-positive varieties. The ability of the bacteria from the clean portion of the karst aquifer to biodegrade benzene and toluene was studied under aerobic and anaerobic conditions in laboratory microcosms. The rate of fuel biodegradation in laboratory studies was approximately 50 times faster under aerobic conditions as compared to anaerobic, sulfur-reducing conditions. The optimum pH for fuel biodegradation ranged from 6 to 7. These findings suggest that bacteria have adapted to water-saturated karst systems with a variety of active and passive transport mechanisms.

Byl, Thomas D.; Metge, David W.; Daniel T. Agymang; Bradley, Michael W.; Hileman, Gregg; Harvey, Ronald W.

2014-01-01

374

Magnetotactic Bacteria from Extreme Environments  

NASA Astrophysics Data System (ADS)

Magnetotactic bacteria (MTB) represent a diverse collection of motile prokaryotes that biomineralize intracellular, membrane-bounded, tens-of-nanometer-sized crystals of a magnetic mineral called magnetosomes. Magnetosome minerals consist of either magnetite (Fe3O4) or greigite (Fe3S4) and cause cells to align along the Earth's geomagnetic field lines as they swim, a trait called magnetotaxis. MTB are known to mainly inhabit the oxic-anoxic interface (OAI) in water columns or sediments of aquatic habitats and it is currently thought that magnetosomes function as a means of making chemotaxis more efficient in locating and maintaining an optimal position for growth and survival at the OAI. Known cultured and uncultured MTB are phylogenetically associated with the Alpha-, Gamma- and Deltaproteobacteria classes of the phylum Proteobacteria, the Nitrospirae phylum and the candidate division OP3, part of the Planctomycetes-Verrucomicrobia-Chlamydiae (PVC) bacterial superphylum. MTB are generally thought to be ubiquitous in aquatic environments as they are cosmopolitan in distribution and have been found in every continent although for years MTB were thought to be restricted to habitats with pH values near neutral and at ambient temperature. Recently, however, moderate thermophilic and alkaliphilic MTB have been described including: an uncultured, moderately thermophilic magnetotactic bacterium present in hot springs in northern Nevada with a probable upper growth limit of about 63 °C; and several strains of obligately alkaliphilic MTB isolated in pure culture from different aquatic habitats in California, including the hypersaline, extremely alkaline Mono Lake, with an optimal growth pH of >9.0.

Bazylinski, Dennis A.; Lefère, Christopher T.

2013-03-01

375

Magnetotactic bacteria from extreme environments.  

PubMed

Magnetotactic bacteria (MTB) represent a diverse collection of motile prokaryotes that biomineralize intracellular, membrane-bounded, tens-of-nanometer-sized crystals of a magnetic mineral called magnetosomes. Magnetosome minerals consist of either magnetite (Fe3O4) or greigite (Fe3S4) and cause cells to align along the Earth's geomagnetic field lines as they swim, a trait called magnetotaxis. MTB are known to mainly inhabit the oxic-anoxic interface (OAI) in water columns or sediments of aquatic habitats and it is currently thought that magnetosomes function as a means of making chemotaxis more efficient in locating and maintaining an optimal position for growth and survival at the OAI. Known cultured and uncultured MTB are phylogenetically associated with the Alpha-, Gamma- and Deltaproteobacteria classes of the phylum Proteobacteria, the Nitrospirae phylum and the candidate division OP3, part of the Planctomycetes-Verrucomicrobia-Chlamydiae (PVC) bacterial superphylum. MTB are generally thought to be ubiquitous in aquatic environments as they are cosmopolitan in distribution and have been found in every continent although for years MTB were thought to be restricted to habitats with pH values near neutral and at ambient temperature. Recently, however, moderate thermophilic and alkaliphilic MTB have been described including: an uncultured, moderately thermophilic magnetotactic bacterium present in hot springs in northern Nevada with a probable upper growth limit of about 63 °C; and several strains of obligately alkaliphilic MTB isolated in pure culture from different aquatic habitats in California, including the hypersaline, extremely alkaline Mono Lake, with an optimal growth pH of >9.0. PMID:25369742

Bazylinski, Dennis A; Lefèvre, Christopher T

2013-01-01

376

Protein(s) from the Gram-Positive Bacterium Clavibacter michiganensis subsp. michiganensis Induces a Hypersensitive Response in Plants.  

PubMed

ABSTRACT The gram-positive tomato pathogen Clavibacter michiganensis subsp. michiganensis induced a local necrotic response on four-o'clock (Mirabilis jalapa) and tobacco (Nicotiana tabacum) plants. This necrosis response was characteristic of the hypersensitive response (HR). The cell-free culture supernatant from strain CMM623 also induced a necrosis that was phenotypically similar to that induced by the bacteria. Inhibitors of plant metabolism suppressed the necrotic reaction of both M. jalapa and tobacco. The HR-inducing activity present in the supernatant was heat stable, sensitive to proteases, and had an apparent molecular mass in the range of 35 to 50 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The properties observed for the necrosis-inducing activity resembled harpin and PopA described from gram-negative phytopathogenic bacteria. PMID:18944953

Alarcón, C; Castro, J; Muñoz, F; Arce-Johnson, P; Delgado, J

1998-04-01

377

Physiological assessment of bacteria using fluorochromes  

NASA Technical Reports Server (NTRS)

This minireview focuses on the application of fluorogenic compounds in the detection of bacteria with particular emphasis on the assessment of physiological activity using epifluorescence microscopy. Microbiological applications of several related methods will also be reviewed.

McFeters, G. A.; Yu, F. P.; Pyle, B. H.; Stewart, P. S.

1995-01-01

378

[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

379

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

380

Methods for dispersing hydrocarbons using autoclaved bacteria  

DOEpatents

A method of dispersing a hydrocarbon includes the 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 thereof; autoclaving the bacterium to derive a dispersant solution therefrom; 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 thereof; and autoclaving the bacterium to derive a dispersant solution therefrom.

Tyndall, Richard L. (Clinton, TN)

1996-01-01

381

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

382

Comparative genomics of the lactic acid bacteria  

SciTech Connect

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.

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.; Rokhsar, 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.

2006-06-01

383

Coevolutionary arms races between bacteria and bacteriophage  

E-print Network

Coevolutionary arms races between bacteria and bacteriophage J. S. Weitz* , H. Hartman , and S. A coevolutionary dynamics of bacteriophage and bac- teria in their ecological context. Bacteriophage enter host

Weitz, Joshua S.

384

DECONTAMINATION OF HEAVY METALS WITH BACTERIA  

EPA Science Inventory

OBJECTIVES: To discover, improve, understand the mechanisms and use naturally occurring bacteria to decontiminate in situ heavy metals from the soils, sediments and waters to protect human health and the environment. ABSTRACT: Our laboratory (Vesper et al. ...

385

Acidophilic, Heterotrophic Bacteria of Acidic Mine Waters  

PubMed Central

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 employed as the hardening agent. Bacterial densities in natural mine waters ranged from approximately 20 to 250 cells per ml, depending upon source and culture medium. Ferric hydrates and stream vegetation contained from 1,500 to over 7 × 106 cells per g. Images PMID:16345777

Wichlacz, Paul L.; Unz, Richard F.

1981-01-01

386

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.; Díaz-Muñiz, 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

387

Protection of probiotic bacteria in synbiotic matrices  

Technology Transfer Automated Retrieval System (TEKTRAN)

Probiotics, like Lactobacillus acidophilus, Lactobacillus reuteri, Bifidobacterium breve, Bifidobacterium longum, when encapsulated with prebiotic fibers such as fructo-oligosaccharides (FOS), inulin (I) and pectic-oligosaccharides (POS), formed a synbiotic matrix system that protected the bacteria ...

388

Fuel from Bacteria: Bioconversion of Carbon Dioxide to Biofuels by Facultatively Autotrophic Hydrogen Bacteria  

SciTech Connect

Electrofuels Project: Ohio State is genetically modifying bacteria to efficiently convert carbon dioxide directly into butanol, an alcohol that can be used directly as a fuel blend or converted to a hydrocarbon, which closely resembles a gasoline. Bacteria are typically capable of producing a certain amount of butanol before it becomes too toxic for the bacteria to survive. Ohio State is engineering a new strain of the bacteria that could produce up to 50% more butanol before it becomes too toxic for the bacteria to survive. Finding a way to produce more butanol more efficiently would significantly cut down on biofuel production costs and help make butanol cost competitive with gasoline. Ohio State is also engineering large tanks, or bioreactors, to grow the biofuel-producing bacteria in, and they are developing ways to efficiently recover biofuel from the tanks.

None

2010-07-01

389

Essential Oils Against Foodborne Pathogens and Spoilage Bacteria in Minced Meat  

PubMed Central

Abstract The antimicrobial activity of essential oils of oregano, thyme, basil, marjoram, lemongrass, ginger, and clove was investigated in vitro by agar dilution method and minimal inhibitory concentration (MIC) determination against Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative strains (Escherichia coli and Salmonella Enteritidis). MIC90% values were tested against bacterial strains inoculated experimentally in irradiated minced meat and against natural microbiota (aerobic or facultative, mesophilic, and psychrotrophic bacteria) found in minced meat samples. MIC90% values ranged from 0.05%v/v (lemongrass oil) to 0.46%v/v (marjoram oil) to Gram-positive bacteria and from 0.10%v/v (clove oil) to 0.56%v/v (ginger oil) to Gram-negative strains. However, the MIC90% assessed on minced meat inoculated experimentally with foodborne pathogen strains and against natural microbiota of meat did not show the same effectiveness, and 1.3 and 1.0 were the highest log CFU/g reduction values obtained against tested microorganisms. PMID:19580445

Barbosa, Lidiane Nunes; Rall, Vera Lucia Mores; Fernandes, Ana Angélica Henrique; Ushimaru, Priscila Ikeda; da Silva Probst, Isabella

2009-01-01

390

Relevance and application of sortase and sortase-dependent proteins in lactic acid bacteria  

PubMed Central

Lactic acid bacteria (LAB) are a diverse group of Gram-positive bacteria found in a vast array of environments including dairy products and the human gastrointestinal tract (GIT). In both niches, surface proteins play a crucial role in mediating interactions with the surrounding environment. The sortase enzyme is responsible for covalently coupling a subset of sortase-dependent proteins (SDPs) to the cell wall of Gram-positive organisms through recognition of a conserved C-terminal LPXTG motif. Genomic sequencing of LAB and annotation has allowed for the identification of sortase and SDPs. Historically, sortase and SDPs were predominately investigated for their role in mediating pathogenesis. Identification of these proteins in LAB has shed light on their important roles in mediating nutrient acquisition through proteinase P as well as positive probiotic attributes including adhesion, mucus barrier function, and immune signaling. Furthermore, sortase expression signals in LAB have been exploited as a means to develop oral vaccines targeted to the GIT. In this review, we examine the collection of studies which evaluate sortase and SDPs in select species of dairy-associated and health promoting LAB. PMID:23579319

Call, Emma K.; Klaenhammer, Todd R.

2013-01-01

391

Tributyltin-resistant bacteria from estuarine and freshwater sediments.  

PubMed Central

Resistance to tributyltin (TBT) was examined in populations from TBT-polluted sediments and nonpolluted sediments from an estuary and from fresh water as well as in pure cultures isolated from those sediments. The 50% effective concentrations (EC50s) for populations were higher at a TBT-polluted freshwater site than at a site without TBT, suggesting that TBT selected for a TBT-resistant population. In contrast, EC50s were significantly lower for populations from a TBT-contaminated estuarine site than for those from a site without TBT, suggesting that other factors in addition to TBT determine whether populations become resistant. EC50s for populations from TBT-contaminated freshwater sediments were nearly 30 times higher than those for populations from TBT-contaminated estuarine sediments. We defined a TBT-resistant bacterium as one which grows on trypticase soy agar containing 8.4 microM TBT, a concentration which prevented the growth of 90% of the culturable bacteria from these sediments. The toxicity of TBT in laboratory media was influenced markedly by the composition of the medium and whether it was liquid or solid. Ten TBT-resistant isolates from estuarine sediments and 19 from freshwater sediments were identified to the genus level. Two isolates, each a Bacillus sp., may be the first gram-positive bacteria isolated from fresh water in the presence of a high concentration of TBT. There was a high incidence of resistance to heavy metals: metal resistance indices were 0.76 for estuarine isolates and 0.68 for freshwater isolates.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1746939

Wuertz, S; Miller, C E; Pfister, R M; Cooney, J J

1991-01-01

392

NOTE: Survivability of Bacteria in Hypervelocity Impact  

Microsoft Academic Search

Bacteria belonging to the genus Rhodococcus have been tested for their survivability in hypervelocity impacts at 5.1+\\/-0.1 km s-1. This is similar to the martian escape velocity for example but is slower than the mean velocities typical of impacts from space on planets like Mars (typically 14 km s-1) and Earth (typically 20-25 km s-1). The bacteria fired were loaded

Mark J. Burchell; Jo Mann; Alan W. Bunch; Pedro F. B. Brandão

2001-01-01

393

Survivability of Bacteria in Hypervelocity Impact  

Microsoft Academic Search

Bacteria belonging to the genus Rhodococcus have been tested for their survivability in hypervelocity impacts at 5.1±0.1 km s?1. This is similar to the martian escape velocity for example but is slower than the mean velocities typical of impacts from space on planets like Mars (typically 14 km s?1) and Earth (typically 20–25 km s?1). The bacteria fired were loaded

Mark J. Burchell; Jo Mann; Alan W. Bunch; Pedro F. B. Brandão

2001-01-01

394

Potentials of Exopolysaccharides from Lactic Acid Bacteria  

Microsoft Academic Search

Recent research in the area of importance of microbes has revealed the immense industrial potential of exopolysaccharides\\u000a and their derivative oligosaccharides from lactic acid bacteria. However, due to lack of adequate technological knowledge,\\u000a the exopolysaccharides have remained largely under exploited. In the present review, the enormous potentials of different\\u000a types of exopolysaccharides from lactic acid bacteria are described. This also

Seema Patel; Avishek Majumder; Arun Goyal

395

[Conjugation mapping of Pseudomonas mendocina bacteria].  

PubMed

Donor strains of the Hfr type were isolated using plasmid pRK2013 with transposons Tn10 and Tn5 as a chromosome-mobilizing factor. The isolated strains were shown to promote transfer of donor chromosome from different origins in different directions during isogenic matings of Pseudomonas mendocina bacteria. The created collection of donors and polyauxotrophic recipient bacteria permitted mapping 26 genetic determinants on the bacterial chromosome and identifying the genome of these microorganisms as a circular DNA molecule. PMID:14714457

Vasilenko, S L; Maksimova, N P; Titok, M A

2003-11-01

396

Bioluminescent hydrocarbonclastic bacteria of the Niger Delta  

Microsoft Academic Search

in the brackish and marine waters of the Niger Delta, representing 7.5-18.72% and 0-2-5% of the total heterotrophic bacteria of the marine and brackish water systems, respectively. A hydrocarbon loss of 100% by week 7 for all four-test organisms was observed. These results indicated that the bacteria were capable of utilizing the hydrocarbon sources as sole sources of carbon and

A. A. Adoki; L. O. Odokuma

397

Agencies Approve Bacteria TMDL Task Force Recommendations  

E-print Network

tx H2O | pg. 10 In June 2007 the Texas Commission onEnvironmental Quality (TCEQ) and the TexasState Soil and Water Conservation Board (TSSW- CB) approved the recommendations of the Bacteria Total Maximum Daily Load (TMDL) Task Force and asked... their agencies to update their TMDL guidance documents to reflect these recommendations. They also authorized establishing a multi-agency bacteria TMDL work group to examine the research and development needs identified in the task force report. Both TCEQ...

Wythe, Kathy

2007-01-01

398

The Continuous Culture of Anaerobic Bacteria  

Microsoft Academic Search

SUMMARY Modifications to an anaerobic continuous culture apparatus to allow pH control, and pH and Eh measurements, are described. Two anaerobic rumen bacteria were grown under different conditions, but as carbohydrate-limited cultures. The effects of growth rate, pH value and Eh value on yields of bacteria, enzyme activities and fermentation products are described. Optimum bacterial yields per mole of substrate

P. N. HOBSON; R. SUMMERS

1967-01-01

399

Biocompatible nanoparticles trigger rapid bacteria clustering.  

PubMed

This study reveals an exciting phenomenon of stimulated bacteria clustering. Rapid aggregation and microbial arrest are shown to occur in Escherichia coli solutions of neutral pH when chitosan nanoparticles with positive zeta potential are added. Because chitosan nanoparticles can easily be dispersed in aqueous buffers, the rapid clustering phenomenon requires only minuscule nanoparticle concentrations and will be critical in developing new methods for extricating bacterial pathogens. This work establishes the dominant role of electrostatic attraction in bacteria-nanoparticle interactions by varying the nanoparticle zeta potential from highly positive to strongly negative values, and by exploring concentration effects. For strongly negative nanoparticles, no clusters form, while aggregates are small and loose at intermediate conditions. In addition, optical density measurements indicate that over 90% of the suspended bacteria flocculate within seconds of being mixed with chitosan nanoparticles of a highly positive surface charge. Finally, the nanoparticles are significantly more efficient as a clustering agent compared to an equal mass of molecular chitosan in solution, as the bacteria-nanoparticle clusters formed are substantially larger. The bacteria-nanoparticle aggregation effect demonstrated here promises a rapid separation method for aiding pathogen detection and for flocculation of bacteria in fermentation processes. PMID:19565661

Larsen, Mona Utne; Seward, Matthew; Tripathi, Anubhav; Shapley, Nina C

2009-01-01

400

Polymer-Immobilized Photosensitizers for Continuous Eradication of Bacteria  

PubMed Central

The photosensitizers Rose Bengal (RB) and methylene blue (MB), when immobilized in polystyrene, were found to exhibit high antibacterial activity in a continuous regime. The photosensitizers were immobilized by dissolution in chloroform, together with polystyrene, with further evaporation of the solvent, yielding thin polymeric films. Shallow reservoirs, bottom-covered with these films, were used for constructing continuous-flow photoreactors for the eradication of Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli and wastewater bacteria under illumination with visible white light using a luminescent lamp at a 1.8 mW·cm?2 fluence rate. The bacterial concentration decreased by two to five orders of magnitude in separate reactors with either immobilized RB or MB, as well as in three reactors connected in series, which contained one of the photosensitizers. Bacterial eradication reached more than five orders of magnitude in two reactors connected in series, where the first reactor contained immobilized RB and the second contained immobilized MB. PMID:25158236

Valkov, Anton; Nakonechny, Faina; Nisnevitch, Marina

2014-01-01

401

A metagenomic assessment of the bacteria associated with Lucilia sericata and Lucilia cuprina (Diptera: Calliphoridae).  

PubMed

Lucilia Robineau-Desvoidy (Diptera: Calliphoridae) is a blow fly genus of forensic, medical, veterinary, and agricultural importance. This genus is also famous because of its beneficial uses in maggot debridement therapy (MDT). Although the genus is of considerable economic importance, our knowledge about microbes associated with these flies and how these bacteria are horizontally and trans-generationally transmitted is limited. In this study, we characterized bacteria associated with different life stages of Lucilia sericata (Meigen) and Lucilia cuprina (Wiedemann) and in the salivary gland of L. sericata by using 16S rDNA 454 pyrosequencing. Bacteria associated with the salivary gland of L. sericata were also characterized using light and transmission electron microscopy (TEM). Results from this study suggest that the majority of bacteria associated with these flies belong to phyla Proteobacteria, Firmicutes, and Bacteroidetes, and most bacteria are maintained intragenerationally, with a considerable degree of turnover from generation to generation. In both species, second-generation eggs exhibited the highest bacterial phylum diversity (20 % genetic distance) than other life stages. The Lucilia sister species shared the majority of their classified genera. Of the shared bacterial genera, Providencia, Ignatzschineria, Lactobacillus, Lactococcus, Vagococcus, Morganella, and Myroides were present at relatively high abundances. Lactobacillus, Proteus, Diaphorobacter, and Morganella were the dominant bacterial genera associated with a survey of the salivary gland of L. sericata. TEM analysis showed a sparse distribution of both Gram-positive and Gram-negative bacteria in the salivary gland of L. sericata. There was more evidence for horizontal transmission of bacteria than there was for trans-generational inheritance. Several pathogenic genera were either amplified or reduced by the larval feeding on decomposing liver as a resource. Overall, this study provides information on bacterial communities associated with different life stages of Lucilia and their horizontal and trans-generational transmission, which may help in the development of better vector-borne disease management and MDT methods. PMID:25306907

Singh, Baneshwar; Crippen, Tawni L; Zheng, Longyu; Fields, Andrew T; Yu, Ziniu; Ma, Qun; Wood, Thomas K; Dowd, Scot E; Flores, Micah; Tomberlin, Jeffery K; Tarone, Aaron M

2014-10-14

402

Identification of intracellular bacteria in the basal plate of the human placenta in term and preterm gestations  

PubMed Central

Objective Bacteria have been identified in different regions of the placenta. Here, we tested the hypothesis that the maternal basal plate of the placenta harbors microbes which may be associated with adverse pregnancy outcomes. Study Design We performed a cross-sectional study of pregnancies from a single tertiary care hospital. Maternal medical and obstetric characteristics were obtained and pregnancies followed prospectively for outcomes and placental collection. After delivery, systematic random sampling of the placental basal plate was performed. Paraffin sections of basal plates were stained with four histological stains and scored for morphological evidence of bacteria. Results Of 195 total patients in the study, Gram positive and negative intracellular bacteria of diverse morphologies were documented in the basal plates of 27% of all placentas. 35% of the patients delivered preterm. No difference was noted between placental basal plates from preterm or term gestations. Intracellular bacteria were found in the placental basal plates of 54% spontaneous preterm deliveries before 28 weeks, and in 26% of term spontaneous deliveries (p=0.02). Intracellular bacteria were also documented in placentas without clinical or pathologic chorioamnionitis. Conclusions 27% of placentas demonstrated intracellular bacteria in the placental basal plate using morphological techniques. Thus, the maternal basal plate is a possible source of intrauterine colonization and placental pathological examination could include examination for bacteria in this important maternal fetal interface. PMID:23333552

Stout, Molly J.; Conlon, Bridget; Landeau, Michele; Lee, Iris; Bower, Carolyn; Zhao, Qiuhong; Roehl, Kimberly A; Nelson, D. Michael; Macones, George A.; Mysorekar, Indira U.

2013-01-01

403

The activity of bacteriocins from Carnobacterium maltaromaticum UAL307 against gram-negative bacteria in combination with EDTA treatment.  

PubMed

Bacteriocins from gram-positive bacteria are potent antimicrobial peptides that inhibit pathogenic and food-spoilage bacteria. They are usually ineffective against gram-negative bacteria because they cannot penetrate the outer membrane (OM). Disruption of the OM of some gram-negative bacteria was reported to sensitize them to certain bacteriocins. This study evaluates the activity of three purified bacteriocins [carnocyclin A (CclA), carnobacteriocin BM1 (CbnBM1) and piscicolin 126 (PisA)] produced by Carnobacterium maltaromaticum UAL307, which has been approved for preservation of food in United States and Canada, against three gram-negative bacteria (Escherichia coli DH5?, Pseudomonas aeruginosa ATCC 14207 and Salmonella Typhimurium ATCC 23564). Their efficacy is compared with bacteriocins of other classes: the lantibiotics nisin A (positive control) and gallidermin, and the cyclic peptide subtilosin A (SubA). In combination with EDTA, CclA inhibited both E. coli and Pseudomonas. PisA inhibited Pseudomonas, but CbnBM1 showed weak activity toward Pseudomonas. In comparison, nisin and gallidermin inhibited the growth of all three strains, whereas SubA was active against E. coli and Pseudomonas only at high concentrations. The results reveal that UAL307 bacteriocins can inhibit gram-negative bacteria if the OM is weakened, and that the different classes of bacteriocins in this study exert unique modes of action toward such bacteria. PMID:21255070

Martin-Visscher, Leah A; Yoganathan, Sabesan; Sit, Clarissa S; Lohans, Christopher T; Vederas, John C

2011-04-01

404

Comparative genome?wide analysis of small RNAs of major Gram?positive pathogens: from identification to application  

PubMed Central

Summary In the recent years, the number of drug? and multi?drug?resistant microbial strains has increased rapidly. Therefore, the need to identify innovative approaches for development of novel anti?infectives and new therapeutic targets is of high priority in global health care. The detection of small RNAs (sRNAs) in bacteria has attracted considerable attention as an emerging class of new gene expression regulators. Several experimental technologies to predict sRNA have been established for the Gram?negative model organism Escherichia coli. In many respects, sRNA screens in this model system have set a blueprint for the global and functional identification of sRNAs for Gram?positive microbes, but the functional role of sRNAs in colonization and pathogenicity for Listeria monocytogenes, Staphylococcus aureus, Streptococcus pyogenes, Enterococcus faecalis and Clostridium difficile is almost completely unknown. Here, we report the current knowledge about the sRNAs of these socioeconomically relevant Gram?positive pathogens, overview the state?of?the?art high?throughput sRNA screening methods and summarize bioinformatics approaches for genome?wide sRNA identification and target prediction. Finally, we discuss the use of modified peptide nucleic acids (PNAs) as a novel tool to inactivate potential sRNA and their applications in rapid and specific detection of pathogenic bacteria. PMID:21255362

Mraheil, Mobarak A.; Billion, André; Kuenne, Carsten; Pischimarov, Jordan; Kreikemeyer, Bernd; Engelmann, Susanne; Hartke, Axel; Giard, Jean?Christophe; Rupnik, Maja; Vorwerk, Sonja; Beier, Markus; Retey, Julia; Hartsch, Thomas; Jacob, Anette; Cemi?, Franz; Hemberger, Jürgen; Chakraborty, Trinad; Hain, Torsten

2010-01-01

405

Caenorhabditis elegans Immune Conditioning with the Probiotic Bacterium Lactobacillus acidophilus Strain NCFM Enhances Gram-Positive Immune Responses  

PubMed Central

Although the immune response of Caenorhabditis elegans to microbial infections is well established, very little is known about the effects of health-promoting probiotic bacteria on evolutionarily conserved C. elegans host responses. We found that the probiotic Gram-positive bacterium Lactobacillus acidophilus NCFM is not harmful to C. elegans and that L. acidophilus NCFM is unable to colonize the C. elegans intestine. Conditioning with L. acidophilus NCFM significantly decreased the burden of a subsequent Enterococcus faecalis infection in the nematode intestine and prolonged the survival of nematodes exposed to pathogenic strains of E. faecalis and Staphylococcus aureus, including multidrug-resistant (MDR) isolates. Preexposure of nematodes to Bacillus subtilis did not provide any beneficial effects. Importantly, L. acidophilus NCFM activates key immune signaling pathways involved in C. elegans defenses against Gram-positive bacteria, including the p38 mitogen-activated protein kinase pathway (via TIR-1 and PMK-1) and the ?-catenin signaling pathway (via BAR-1). Interestingly, conditioning with L. acidophilus NCFM had a minimal effect on Gram-negative infection with Pseudomonas aeruginosa or Salmonella enterica serovar Typhimurium and had no or a negative effect on defense genes associated with Gram-negative pathogens or general stress. In conclusion, we describe a new system for the study of probiotic immune agents and our findings demonstrate that probiotic conditioning with L. acidophilus NCFM modulates specific C. elegans immunity traits. PMID:22585961

2012-01-01

406

Biosynthesis of auxin by the gram-positive phytopathogen Rhodococcus fascians is controlled by compounds specific to infected plant tissues.  

PubMed

The role and metabolism of indole-3-acetic acid in gram-negative bacteria is well documented, but little is known about indole-3-acetic acid biosynthesis and regulation in gram-positive bacteria. The phytopathogen Rhodococcus fascians, a gram-positive organism, incites diverse developmental alterations, such as leafy galls, on a wide range of plants. Phenotypic analysis of a leafy gall suggests that auxin may play an important role in the development of the symptoms. We show here for the first time that R. fascians produces and secretes the auxin indole-3-acetic acid. Interestingly, whereas noninfected-tobacco extracts have no effect, indole-3-acetic acid synthesis is highly induced in the presence of infected-tobacco extracts when tryptophan is not limiting. Indole-3-acetic acid production by a plasmid-free strain shows that the biosynthetic genes are located on the bacterial chromosome, although plasmid-encoded genes contribute to the kinetics and regulation of indole-3-acetic acid biosynthesis. The indole-3-acetic acid intermediates present in bacterial cells and secreted into the growth media show that the main biosynthetic route used by R. fascians is the indole-3-pyruvic acid pathway with a possible rate-limiting role for indole-3-ethanol. The relationship between indole-3-acetic acid production and the symptoms induced by R. fascians is discussed. PMID:15746315

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

2005-03-01

407

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

PubMed Central

The role and metabolism of indole-3-acetic acid in gram-negative bacteria is well documented, but little is known about indole-3-acetic acid biosynthesis and regulation in gram-positive bacteria. The phytopathogen Rhodococcus fascians, a gram-positive organism, incites diverse developmental alterations, such as leafy galls, on a wide range of plants. Phenotypic analysis of a leafy gall suggests that auxin may play an important role in the development of the symptoms. We show here for the first time that R. fascians produces and secretes the auxin indole-3-acetic acid. Interestingly, whereas noninfected-tobacco extracts have no effect, indole-3-acetic acid synthesis is highly induced in the presence of infected-tobacco extracts when tryptophan is not limiting. Indole-3-acetic acid production by a plasmid-free strain shows that the biosynthetic genes are located on the bacterial chromosome, although plasmid-encoded genes contribute to the kinetics and regulation of indole-3-acetic acid biosynthesis. The indole-3-acetic acid intermediates present in bacterial cells and secreted into the growth media show that the main biosynthetic route used by R. fascians is the indole-3-pyruvic acid pathway with a possible rate-limiting role for indole-3-ethanol. The relationship between indole-3-acetic acid production and the symptoms induced by R. fascians is discussed. PMID:15746315

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

2005-01-01

408

Comparison of the Bruker MALDI-TOF Mass Spectrometry System and Conventional Phenotypic Methods for Identification of Gram-Positive Rods  

PubMed Central

In recent years, MALDI-TOF Mass Spectrometry (MS) method has emerged as a promising and a reliable tool for bacteria identification. In this study we compared Bruker MALDI-TOF MS and conventional phenotypic methods to identify a collection of 333 Gram-positive clinical isolates comprising 22 genera and 60 species. 16S rRNA sequencing was the reference molecular technique, and rpoB gene sequecing was used as a secondary gene target when 16Sr RNA did not allow species identification of Corynebacterium spp. We also investigate if score cut-offs values of ?1,5 and ?1,7 were accurate for genus and species-level identification using the Bruker system. Identification at species level was obtained for 92,49% of Gram-positive rods by MALDI-TOF MS compared to 85,89% by phenotypic method. Our data validates the score ?1,5 for genus level and ?1,7 for species-level identification in a large and diverse collection of Gram-positive rods. The present study has proved the accuracy of MALDI-TOF MS as an identification method in Gram-positive rods compared to currently used methods in routine laboratories. PMID:25184254

Barberis, Claudia; Almuzara, Marisa; Join-Lambert, Olivier; Ramírez, María Soledad; Famiglietti, Angela; Vay, Carlos

2014-01-01

409

Visualizing Bacteria in Nematodes using Fluorescent Microscopy  

PubMed Central

Symbioses, the living together of two or more organisms, are widespread throughout all kingdoms of life. As two of the most ubiquitous organisms on earth, nematodes and bacteria form a wide array of symbiotic associations that range from beneficial to pathogenic 1-3. One such association is the mutually beneficial relationship between Xenorhabdus bacteria and Steinernema nematodes, which has emerged as a model system of symbiosis 4. Steinernema nematodes are entomopathogenic, using their bacterial symbiont to kill insects 5. For transmission between insect hosts, the bacteria colonize the intestine of the nematode's infective juvenile stage 6-8. Recently, several other nematode species have been shown to utilize bacteria to kill insects 9-13, and investigations have begun examining the interactions between the nematodes and bacteria in these systems 9. We describe a method for visualization of a bacterial symbiont within or on a nematode host, taking advantage of the optical transparency of nematodes when viewed by microscopy. The bacteria are engineered to express a fluorescent protein, allowing their visualization by fluorescence microscopy. Many plasmids are available that carry genes encoding proteins that fluoresce at different wavelengths (i.e. green or red), and conjugation of plasmids from a donor Escherichia coli strain into a recipient bacterial symbiont is successful for a broad range of bacteria. The methods described were developed to investigate the association between Steinernema carpocapsae and Xenorhabdus nematophila14. Similar methods have been used to investigate other nematode-bacterium associations 9,15-18and the approach therefore is generally applicable. The method allows characterization of bacterial presence and localization within nematodes at different stages of development, providing insights into the nature of the association and the process of colonization 14,16,19. Microscopic analysis reveals both colonization frequency within a population and localization of bacteria to host tissues 14,16,19-21. This is an advantage over other methods of monitoring bacteria within nematode populations, such as sonication 22or grinding 23, which can provide average levels of colonization, but may not, for example, discriminate populations with a high frequency of low symbiont loads from populations with a low frequency of high symbiont loads. Discriminating the frequency and load of colonizing bacteria can be especially important when screening or characterizing bacterial mutants for colonization phenotypes 21,24. Indeed, fluorescence microscopy has been used in high throughput screening of bacterial mutants for defects in colonization 17,18, and is less laborious than other methods, including sonication 22,25-27and individual nematode dissection 28,29. PMID:23117838

Murfin, Kristen E.; Chaston, John; Goodrich-Blair, Heidi

2012-01-01

410

Mechanisms of ?-lactam antimicrobial resistance and epidemiology of major community- and healthcare-associated multidrug-resistant bacteria.  

PubMed

Alexander Fleming's discovery of penicillin heralded an age of antibiotic development and healthcare advances that are premised on the ability to prevent and treat bacterial infections both safely and effectively. The resultant evolution of antimicrobial resistant mechanisms and spread of bacteria bearing these genetic determinants of resistance are acknowledged to be one of the major public health challenges globally, and threatens to unravel the gains of the past decades. We describe the major mechanisms of resistance to ?-lactam antibiotics - the most widely used and effective antibiotics currently - in both Gram-positive and Gram-negative bacteria, and also briefly detail the existing and emergent pharmacological strategies to overcome such resistance. The global epidemiology of the four major types of bacteria that are responsible for the bulk of antimicrobial-resistant infections in the healthcare setting - methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, Enterobactericeae, and Acinetobacter baumannii - are also briefly described. PMID:25134490

Tang, Sarah S; Apisarnthanarak, Anucha; Hsu, Li Yang

2014-11-30

411

MIGHTY BACTERIA IN A CIVILISED WORLD Prepared by Amy Wooding  

E-print Network

MIGHTY BACTERIA IN A CIVILISED WORLD Prepared by Amy Wooding The 2013 FABI/ CTHB UPwith of antibacterial products being advertised. The aim was to explore the idea created by these products that bacteria this by testing whether all bacteria can survive in every environment; will bacteria isolated from the UP

412

Bacteria Total Maximum Daily Load Task Force Final Report  

E-print Network

TR-341 2009 Bacteria Total Maximum Daily Load Task Force Final Report By C. Allan Jones and Kevin Wagner, Texas Water Resources Institute; George Di Giovanni, Texas AgriLife Research; Larry... Introduction 4 Bacteria Fate and Transport Models 6 Bacteria Source Tracking 23 Recommended Approach for Bacteria TMDL and Implementation Plan Development 36...

Jones, C. Allan; Wagner, Kevin; Di Giovanni, George; Hauck, Larry; Mott, Joanna; Rifai, Hanadi; Srinivasan, Raghavan; Ward, George; Wythe, Kathy

413

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

SciTech Connect

Until recently, there have been no clear physiologic predictors of a cell's ability to recover from ionizing radiation (IR), desiccation, and other DOE-relevant oxidative stress conditions. In general, the most resistant bacteria have been Gram-positive (e.g., Deinococcus, Arthrobacter, Lactobacillus & Enterococcus spp.) and the most sensitive have been Gram-negative (e.g., Pseudomonas, Shewanella & Neisseria spp.). However, there are several reported exceptions to this paradigm, the Gram-negative cyanobacterium Chroococcidiopsis is extremely resistant to IR, whereas the Gram-positive Micrococcus luteus is sensitive. We have identified biomolecular signatures for radiation sensitivity and resistance which are independent of phylogeny, where very high and very low intracellular Mn/Fe concentration ratios correlated with very high and very low resistances, respectively; and restricting Mn(II) in the famously resistant Deinococcus radiodurans sensitized this eubacterium to IR (http://cfyn.ifas.ufl.edu/radiation.pdf).

Fredrickson, Jim K.; Daly, Michael J.

2006-06-01

414

Flagellated ectosymbiotic bacteria propel a eucaryotic cell  

PubMed Central

A devescovinid flagellate from termites exhibits rapid gliding movements only when in close contact with other cells or with a substrate. Locomotion is powered not by the cell's own flagella nor by its remarkable rotary axostyle, but by the flagella of thousands of rod bacteria which live on its surface. That the ectosymbiotic bacteria actually propel the protozoan was shown by the following: (a) the bacteria, which lie in specialized pockets of the host membrane, bear typical procaryotic flagella on their exposed surface; (b) gliding continues when the devescovinid's own flagella and rotary axostyle are inactivated; (c) agents which inhibit bacterial flagellar motility, but not the protozoan's motile systems, stop gliding movements; (d) isolated vesicles derived from the surface of the devescovinid rotate at speeds dependent on the number of rod bacteria still attached; (e) individual rod bacteria can move independently over the surface of compressed cells; and (f) wave propagation by the flagellar bundles of the ectosymbiotic bacteria is visualized directly by video-enhanced polarization microscopy. Proximity to solid boundaries may be required to align the flagellar bundles of adjacent bacteria in the same direction, and/or to increase their propulsive efficiency (wall effect). This motility-linked symbiosis resembles the association of locomotory spirochetes with the Australian termite flagellate Mixotricha (Cleveland, L. R., and A. V. Grimstone, 1964, Proc. R. Soc. Lond. B Biol. Sci., 159:668-686), except that in our case propulsion is provided by bacterial flagella themselves. Since bacterial flagella rotate, an additional novelty of this system is that the surface bearing the procaryotic rotary motors is turned by the eucaryotic rotary motor within. PMID:7130279

1982-01-01

415

Chemically enhanced sunlight for killing bacteria  

SciTech Connect

Solar ultraviolet (UV) photocatalyzed oxidation of chemicals with titanium dioxide (TiO{sub 2}) has received considerable attention. Much less recognized, however, is the ability of the same system to destroy bacteria. This study examined this phenomenon and the conditions that affect it. Bacteria in aqueous solution were given solar exposure with titanium dioxide and their survival with time was determined. Lamps with a predominantly solar ultraviolet spectrum were also used in the experiments. Without exposure to UV light, TiO{sub 2} had no deleterious effect on the bacteria. However, several common bacteria on solar exposure in the presence of TiO{sub 2} were killed in just a few minutes, whereas without TiO{sub 2} it took over an hour to destroy them. A concentration of 0.01% TiO{sub 2} was most effective in killing bacteria and 10-fold concentrations lower or higher were successively less effective. Inorganic and organic compounds in solution, even in small amounts, interfered with the efficiency of killing. Alkaline solution also reduced the bactericidal activity. Circulation and agitation provided by stirring to keep the TiO{sub 2} particles suspended reduced the time necessary to kill the bacteria. Time-intensity curves for killing bacteria were the same general shape with or without TiO{sub 2}, indicating that TiO{sub 2} served merely as a catalyst to increase the rate of the reaction but that the mechanism of action was not changed. The shape of the curves show that the organisms are sensitized with a minimum intensity of radiation and that an increase doesn`t greatly increase the rate of kill. Below this critical intensity, however, the time required for killing markedly increases as the intensity is decreased.

Block, S.S.; Goswami, D.Y. [Univ. of Florida, Gainesville, FL (United States)

1995-10-01

416

Bacteria associated with crabs from cold waters with emphasis on the occurrence of potential human pathogens.  

PubMed Central

A diverse array of bacterial species, including several potential human pathogens, was isolated from edible crabs collected in cold waters. Crabs collected near Kodiak Island, Alaska, contained higher levels of bacteria than crabs collected away from regions of human habitation. The bacteria associated with the crabs collected near Kodiak included Yersinia enterocolitica, Klebsiella pneumoniae, and coagulase-negative Staphylococcus species; the pathogenicity of these isolates was demonstrated in mice. Although coliforms were not found, the bacterial species associated with the tissues of crabs collected near Kodiak indicate possible fecal contamination that may have occurred through contact with sewage. Compared with surrounding waters and sediments, the crab tissues contained much higher proportions of gram-positive cocci. As revealed by indirect plate counts and direct scanning electron microscopic observations, muscle and hemolymph tissues contained much lower levels of bacteria than shell and gill tissues. After the death of a crab, however, the numbers of bacteria associated with hemolymph and muscle tissues increased significantly. Microcosm studies showed that certain bacterial populations, e.g., Vibrio cholerae, can be bioaccumulated in crab gill tissues. The results of this study indicate the need for careful review of waste disposal practices where edible crabs may be contaminated with microorganisms that are potential human pathogens and the need for surveillance of shellfish for pathogenic microorganisms that naturally occur in marine ecosystems. Images PMID:6742824

Faghri, M A; Pennington, C L; Cronholm, L S; Atlas, R M

1984-01-01

417

Phenotypic and Genotypic Characterization of Some Lactic Acid Bacteria Isolated from Bee Pollen: A Preliminary Study  

PubMed Central

In the present work, five hundred and sixty-seven isolates of lactic acid bacteria were recovered from raw bee pollen grains. All isolates were screened for their antagonistic activity against both Gram-positive and Gram-negative pathogenic bacteria. Neutralized supernatants of 54 lactic acid bacteria (LAB) cultures from 216 active isolates inhibited the growth of indicator bacteria. They were phenotypically characterized, based on the fermentation of 39 carbohydrates. Using the simple matching coefficient and unweighted pair group algorithm with arithmetic averages (UPGMA), seven clusters with other two members were defined at the 79% similarity level. The following species were characterized: Lactobacillus plantarum, Lactobacillus fermentum, Lactococcus lactis, Pediococcus acidilactici, Pediococcus pentosaceus, and unidentified lactobacilli. Phenotypic characteristics of major and minor clusters were also identified. Partial sequencing of the 16S rRNA gene of representative isolates from each cluster was performed, and ten strains were assigned to seven species: Lactobacillus plantarum, Lactobacillus fermentum, Lactococcus lactis, Lactobacillus ingluviei, Pediococcus pentosaceus, Lactobacillus acidipiscis and Weissella cibaria. The molecular method used failed to determine the exact taxonomic status of BH0900 and AH3133. PMID:24936378

BELHADJ, Hani; HARZALLAH, Daoud; BOUAMRA, Dalila; KHENNOUF, Seddik; Dahamna, Saliha; GHADBANE, Mouloud

2014-01-01

418

[The phylogenetic diversity of aerobic organotrophic bacteria from the Dagan high-temperature oil field].  

PubMed

The distribution and species diversity of aerobic organotrophic bacteria in the Dagan high-temperature oil field (China), which is exploited via flooding, have been studied. Twenty-two strains of the most characteristic thermophilic and mesophilic aerobic organotrophic bacteria have been isolated from the oil stratum. It has been found that, in a laboratory, the mesophilic and thermophilic isolates grow in the temperature, pH, and salinity ranges characteristic of the injection well near-bottom zones or of the oil stratum, respectively, and assimilate a wide range of hydrocarbons, fatty acids, lower alcohols, and crude oil, thus exhibiting adaptation to the environment. Using comparative phylogenetic 16S rRNA analysis, the taxonomic affiliation of the isolates has been established. The aerobic microbial community includes gram-positive bacteria with a high and low G+C content of DNA, and gamma and beta subclasses of Proteobacteria. The thermophilic bacteria belong to the genera Geobacillus and Thermoactinomyces, and the mesophilic strains belong to the genera Bacillus, Micrococcus, Cellulomonas, Pseudomonas, and Acinetobacter. The microbial community of the oil stratum is dominated by known species of the genus Geobacillus (G. subterraneus, G. stearothermophilus, and G. thermoglucosidasius) and a novel species "Geobacillus jurassicus." A number of novel thermophilic oil-oxidizing bacilli have been isolated. PMID:16119855

Nazina, T N; Sokolova, D Sh; Shestakova, N M; Grigor'ian, A A; Mikha?lova, E M; Babich, T L; Lysenko, A M; Turova, T P; Poltaraus, A B; Feng, Tsin'syan; Ni, Fangtian; Beliaev, S S

2005-01-01

419

Identification and antimicrobial susceptibility patterns of bacteria causing otitis externa in dogs.  

PubMed

Bacterial agents are considered important pathogens causing external otitis in dogs. It is essential to carry out bacterial culture and antimicrobial susceptibility test in the case of otitis externa, particularly for chronic or recurring cases. Sterile swab samples were obtained from terminal part of vertical ear canals of 74 dogs with otitis externa for cytology, bacterial culture and antimicrobial susceptibility test. Cytologic smears were stained using Gram and Giemsa staining methods. Aerobic bacterial culture performed on blood agar and MacConkey agar. Among total number of 92 isolated bacteria, 68 were Staphylococcus intermedius. Other isolated bacteria included: Pseudomonas aeruginosa, Proteus mirabilis, Escherichia coli, Pasteurella canis, and six other species of coagulase-negative Staphylococcus. Antimicrobial susceptibility test were performed for all isolated bacteria using 14 antibiotics. Based on the results of this study, all isolated Staphylococcus spp. were sensitive to amikacin, enrofloxacin, and rifampin, and had low resistance to gentamicin, cephalothin and ceftriaxone. More than half of gram-positive isolates were resistant to penicillin and ampicillin. Generally, all isolated gram-negative bacteria, were sensitive to amikacin and enrofloxacin, and had low resistance to ceftriaxone and gentamicin. They were highly resistant to penicillin, eythromycin, and cephalothin. Regarding the results of this study, in cases of uncomplicated otitis externa, it is possible to select antimicrobial drugs merely based on cytology, but it is recommended to perform bacterial culture and antimicrobial susceptibility test. However, in complicated or refractory cases, antimicrobials should be selected based on bacterial culture and antimicrobial susceptibility test. PMID:20526674

Zamankhan Malayeri, Hamed; Jamshidi, Shahram; Zahraei Salehi, Taghi

2010-06-01

420

Using Fluorescent Viruses for Detecting Bacteria in Water  

NASA Technical Reports Server (NTRS)

A method of detecting water-borne pathogenic bacteria is based partly on established molecular-recognition and fluorescent-labeling concepts, according to which bacteria of a species of interest are labeled with fluorescent reporter molecules and the bacteria can then be detected by fluorescence spectroscopy. The novelty of the present method lies in the use of bacteriophages (viruses that infect bacteria) to deliver the fluorescent reporter molecules to the bacteria of the species of interest.

Tabacco, Mary Beth; Qian, Xiaohua; Russo, Jaimie A.

2009-01-01

421

Method of Detecting Coliform Bacteria and Escherichia Coli Bacteria from Reflected Light  

NASA Technical Reports Server (NTRS)

The present invention relates to a method of detecting coliform bacteria in water from reflected light and a method of detecting Eschericha Coli bacteria in water from reflected light, and also includes devices for the measurement, calculation and transmission of data relating to that method.

Vincent, Robert (Inventor)

2013-01-01

422

Single bacteria identification by Raman spectroscopy.  

PubMed

We report on rapid identification of single bacteria using a low-cost, compact, Raman spectroscope. We demonstrate that a 60-s procedure is sufficient to acquire a comprehensive Raman spectrum in the range of 600 to 3300 cm?¹. This time includes localization of small bacteria aggregates, alignment on a single individual, and spontaneous Raman scattering signal collection. Fast localization of small bacteria aggregates, typically composed of less than a dozen individuals, is achieved by lensfree imaging over a large field of view of 24 mm². The lensfree image also allows precise alignment of a single bacteria with the probing beam without the need for a standard microscope. Raman scattered light from a 34-mW continuous laser at 532 nm was fed to a customized spectrometer (prototype Tornado Spectral Systems). Owing to the high light throughput of this spectrometer, integration times as low as 10 s were found acceptable. We have recorded a total of 1200 spectra over seven bacterial species. Using this database and an optimized preprocessing, classification rates of ~90% were obtained. The speed and sensitivity of our Raman spectrometer pave the way for high-throughput and nondestructive real-time bacteria identification assays. This compact and low-cost technology can benefit biomedical, clinical diagnostic, and environmental applications. PMID:25028774

Strola, Samy Andrea; Baritaux, Jean-Charles; Schultz, Emmanuelle; Simon, Anne Catherine; Allier, Cédric; Espagnon, Isabelle; Jary, Dorothée; Dinten, Jean-Marc

2014-11-01

423

Chemotactic selection of pollutant degrading soil bacteria  

SciTech Connect

A method is described for identifying soil microbial strains which may be bacterial degraders of pollutants comprising the steps of 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, collecting the contents of the container, and 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 inoculate 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. 6 figures.

Hazen, T.C.

1994-06-28

424

Chemotactic steering of bacteria propelled microbeads.  

PubMed

Flagellated bacteria have been embraced by the micro-robotics community as a highly efficient microscale actuation method, capable of converting chemical energy into mechanical actuation for microsystems that require a small payload and high rate of actuation. Along with being highly motile, Serratia marcescens (S. marcescens), our bacterium species of interest, is a highly agile biomotor capable of being steered via chemotaxis. In this paper, we attached S. marcescens bacteria to polystyrene microbeads towards creating biohybrid that can propel themselves towards an attractive chemical source. Using a three-channel microfluidic device, linear chemical gradients are generated to compare the behavior of bacteria-propelled beads in the presence and absence of a chemoattractant, L-aspartate. We tested and compared the behavior of three different bacteria-attached bead sizes (5, 10 and 20 ?m diameter) using a visual particle-tracking algorithm, and noted their behavioral differences. The results indicate that in the presence of a chemoattractant, the S. marcescens-attached polystyrene beads exhibit a clear indication of directionality and steering control through the coordination of the bacteria present on each bead. This directionality is observed in all bead size cases, suggesting potential for targeted payload delivery using such a biohybrid micro-robotic approach. PMID:22960953

Kim, Dongwook; Liu, Albert; Diller, Eric; Sitti, Metin

2012-12-01

425

Single bacteria identification by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We report on rapid identification of single bacteria using a low-cost, compact, Raman spectroscope. We demonstrate that a 60-s procedure is sufficient to acquire a comprehensive Raman spectrum in the range of 600 to 3300. This time includes localization of small bacteria aggregates, alignment on a single individual, and spontaneous Raman scattering signal collection. Fast localization of small bacteria aggregates, typically composed of less than a dozen individuals, is achieved by lensfree imaging over a large field of view of 24. The lensfree image also allows precise alignment of a single bacteria with the probing beam without the need for a standard microscope. Raman scattered light from a 34-mW continuous laser at 532 nm was fed to a customized spectrometer (prototype Tornado Spectral Systems). Owing to the high light throughput of this spectrometer, integration times as low as 10 s were found acceptable. We have recorded a total of 1200 spectra over seven bacterial species. Using this database and an optimized preprocessing, classification rates of ˜90% were obtained. The speed and sensitivity of our Raman spectrometer pave the way for high-throughput and nondestructive real-time bacteria identification assays. This compact and low-cost technology can benefit biomedical, clinical diagnostic, and environmental applications.

Strola, Samy Andrea; Baritaux, Jean-Charles; Schultz, Emmanuelle; Simon, Anne Catherine; Allier, Cédric; Espagnon, Isabelle; Jary, Dorothée; Dinten, Jean-Marc

2014-11-01

426

Chemotactic selection of pollutant degrading soil bacteria  

DOEpatents

A method for identifying soil microbial strains which may be bacterial degraders of pollutants comprising the steps of 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, collecting the contents of the container, and 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 inoculate 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, Terry C. (Augusta, GA)

1994-01-01

427

Bacteria dispersal by hitchhiking on zooplankton  

PubMed Central

Microorganisms and zooplankton are both important components of aquatic food webs. Although both inhabit the same environment, they are often regarded as separate functional units that are indirectly connected through nutrient cycling and trophic cascade. However, research on pathogenic and nonpathogenic bacteria has shown that direct association with zooplankton has significant influences on the bacteria's physiology and ecology. We used stratified migration columns to study vertical dispersal of hitchhiking bacteria through migrating zooplankton across a density gradient that was otherwise impenetrable for bacteria in both upward and downward directions (conveyor-belt hypothesis). The strength of our experiments is to permit quantitative estimation of transport and release of associated bacteria: vertical migration of Daphnia magna yielded an average dispersal rate of 1.3 × 105·cells·Daphnia?1·migration cycle?1 for the lake bacterium Brevundimonas sp. Bidirectional vertical dispersal by migrating D. magna was also shown for two other bacterial species, albeit at lower rates. The prediction that diurnally migrating zooplankton acquire different attached bacterial communities from hypolimnion and epilimnion between day and night was subsequently confirmed in our field study. In mesotrophic Lake Nehmitz, D. hyalina showed pronounced diel vertical migration along with significant diurnal changes in attached bacterial community composition. These results confirm that hitchhiking on migrating animals can be an important mechanism for rapidly relocating microorganisms, including pathogens, allowing them to access otherwise inaccessible resources. PMID:20547852

Grossart, Hans-Peter; Dziallas, Claudia; Leunert, Franziska; Tang, Kam W.

2010-01-01

428

Lack of genomic evidence of AI2 receptors suggests a non-quorum sensing role for luxS in most bacteria  

Microsoft Academic Search

BACKGROUND: Great excitement accompanied discoveries over the last decade in several Gram-negative and Gram-positive bacteria of the LuxS protein, which catalyzes production of the AI-2 autoinducer molecule for a second quorum sensing system (QS-2). Since the luxS gene was found to be widespread among the most diverse bacterial taxa, it was hypothesized that AI-2 may constitute the basis of a

Fabio Rezzonico; Brion Duffy

2008-01-01

429

Isolation and Purification of Enteroicin E-760 with a Broad Antimicrobial Activity Against Gram-positive and Gram-negative Bacteria (AAC01569-06 Version 3)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Strain NRRL B-30745, isolated from chicken ceca, and identified as an Enterococcus spp. of the durans/faecium/hirae group, produces a 5362 Da bacteriocin that inhibits the growth of Salmonella enteritidis, S. choleraesuis, S. typhimurium, S. gallinarum, Escherichia coli O157:H7, Yersinia enterocolit...

430

Silver nanocrystallites: Facile biofabrication using Shewanella oneidensis, and an evaluation of their comparative toxicity on Gram-negative and Gram-positive bacteria  

Microsoft Academic Search

Microorganisms have long been known to develop resistance to metal ions either by sequestering metals inside the cell or by effluxing them into the extracellular media. Here we report the biosynthesis of extracellular silver based single nanocrystallites of well-defined composition and homogeneous morphology utilizing the -proteobacterium, Shewanella oneidensis strain MR-1, upon incubation with an aqueous solution of silver nitrate. Further

Anil K Suresh; Wei Wang; Dale A Pelletier; Ji Won Moon; Baohua Gu; Ninell P Mortensen; David P Allison; David Charles Joy; Tommy Joe Phelps; Mitchel John Doktycz

2010-01-01

431

Indigenous oil-degrading bacteria in crude oil-contaminated seawater of the Yellow sea, China.  

PubMed

Indigenous oil-degrading bacteria play an important role in efficient remediation of polluted marine environments. In this study, we investigated the diversity and abundance of indigenous oil-degrading bacteria and functional genes in crude oil-contaminated seawater of the Dalian coast. The gene copy number bacterial 16S rRNA in total were determined to be about 10(10) copies L(-1) in contaminated seawater and 10(9) copies L(-1) in uncontaminated seawater. Bacteria of Alcanivorax, Marinobacter, Novosphingobium, Rhodococcus, and Pseudoalteromonas were found to be predominant oil-degrading bacteria in the polluted seawater in situ. In addition, bacteria belonging to Algoriphagus, Aestuariibacter, Celeribacter, Fabibacter, Zobellia, Tenacibaculum, Citreicella, Roseivirga, Winogradskyella, Thioclava, Polaribacter, and Pelagibaca were confirmed to be the first time as an oil-degrading bacterium. The indigenous functional enzymes, including AlkB or polycyclic aromatic hydrocarbons ring-hydroxylating dioxygenases ? (PAH-RHD?) coding genes from Gram-positive (GP) and Gram-negative bacteria (GN), were revealed and quite diverse. About 10(10) to 10(11) copies L(-1) for the expression of alkB genes were recovered and showed that the two-thirds of all the AlkB sequences were closely related to widely distributed Alcanivorax and Marinobacter isolates. About 10(9) copies L(-1) seawater for the expression of RHD?GN genes in contaminated seawater and showed that almost all RHD?GN sequences were closely related to an uncultured bacterium; however, RHD?GP genes represented only about 10(5) copies L(-1) seawater for the expression of genes in contaminated seawater, and the naphthalene dioxygenase sequences from Rhodococcus and Mycobacterium species were most abundant. Together, their data provide evidence that there exists an active aerobic microbial community indigenous to the coastal area of the Yellow sea that is capable of degrading petroleum hydrocarbons. PMID:24866944

Wang, Wanpeng; Zhong, Rongqiu; Shan, Dapeng; Shao, Zongze

2014-08-01

432

In vitro antibacterial potency of Butea monosperma Lam. against 12 clinically isolated multidrug resistant bacteria  

PubMed Central

Objective To investigate the antibacterial activity, using cold and hot extraction procedures with five solvents, petroleum ether, acetone, ethanol, methanol and water to validate medicinal uses of Butea monosperma Lam (B. monosperma) in controlling infections; and to qualitatively estimate phytochemical constituents of leaf-extracts of the plant. Methods The antibacterial activity of leaf-extracts was evaluated by the agar-well diffusion method against clinically isolated 12 Gram-positive and -negative multidrug resistant (MDR) pathogenic bacteria in vitro. Values of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of leaf-extracts against each bacterium were obtained in a 96-well micro-titre plate, by broth dilution micro-titre plate technique. Results The presence of tannins, flavonoids, starch, glycosides and carbohydrates in different leaf extracts was established. Pathogenic bacteria used were, Acinetobacter sp., Chromobacterium violaceum, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella sp., Enterococcus sp., Staphylococcus aureus (S. aureus), methicillin resistant S. aureus and vancomycin resistant S. aureus, along with standard bacterial strains. These MDR bacteria had been recorded to have significant inhibitions by leaf extracts, obtained by cold and hot extraction procedures with five solvents. In addition, the hot aqueous extract against Enterococcus sp. had the highest inhibition zone-size (21 mm). Ciprofloxacin 30 µg/disc was the positive/reference control and the diluting solvent, 10% dimethyl sulphoxide was the negative control. Recorded MIC values of different extracts ranged between 0.23 and 13.30 mg/mL, and MBC values were 0.52 to 30.00 mg/mL, for these bacteria. Conclusions Leaf-extracts with hot water and ethanol had shown significant antibacterial activity against all bacteria. B. monosperma leaf-extract could be used in treating infectious diseases, caused by the range of tested bacteria, as complementary and alternate medicine.

Sahu, Mahesh Chandra; Padhy, Rabindra Nath

2013-01-01

433

Crystallization and first data collection of the putative transfer protein TraN from the Gram-positive conjugative plasmid pIP501  

PubMed Central

Conjugative plasmid transfer is the most important route for the spread of resistance and virulence genes among bacteria. Consequently, bacteria