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Sample records for h2 producing bacteria

  1. Purification and characterization of a surfactin-like molecule produced by Bacillus sp. H2O-1 and its antagonistic effect against sulfate reducing bacteria

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    Korenblum Elisa

    2012-11-01

    Full Text Available Abstract Background Bacillus sp. H2O-1, isolated from the connate water of a Brazilian reservoir, produces an antimicrobial substance (denoted as AMS H2O-1 that is active against sulfate reducing bacteria, which are the major bacterial group responsible for biogenic souring and biocorrosion in petroleum reservoirs. Thus, the use of AMS H2O-1 for sulfate reducing bacteria control in the petroleum industry is a promising alternative to chemical biocides. However, prior to the large-scale production of AMS H2O-1 for industrial applications, its chemical structure must be elucidated. This study also analyzed the changes in the wetting properties of different surfaces conditioned with AMS H2O-1 and demonstrated the effect of AMS H2O-1 on sulfate reducing bacteria cells. Results A lipopeptide mixture from AMS H2O-1 was partially purified on a silica gel column and identified via mass spectrometry (ESI-MS. It comprises four major components that range in size from 1007 to 1049 Da. The lipid moiety contains linear and branched β-hydroxy fatty acids that range in length from C13 to C16. The peptide moiety contains seven amino acids identified as Glu-Leu-Leu-Val-Asp-Leu-Leu. Transmission electron microscopy revealed cell membrane alteration of sulfate reducing bacteria after AMS H2O-1 treatment at the minimum inhibitory concentration (5 μg/ml. Cytoplasmic electron dense inclusions were observed in treated cells but not in untreated cells. AMS H2O-1 enhanced the osmosis of sulfate reducing bacteria cells and caused the leakage of the intracellular contents. In addition, contact angle measurements indicated that different surfaces conditioned by AMS H2O-1 were less hydrophobic and more electron-donor than untreated surfaces. Conclusion AMS H2O-1 is a mixture of four surfactin-like homologues, and its biocidal activity and surfactant properties suggest that this compound may be a good candidate for sulfate reducing bacteria control. Thus, it is a potential

  2. Linking genome content to biofuel production yields: a meta-analysis of major catabolic pathways among select H2 and ethanol-producing bacteria

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    Carere Carlo R

    2012-12-01

    Full Text Available Abstract Background Fermentative bacteria offer the potential to convert lignocellulosic waste-streams into biofuels such as hydrogen (H2 and ethanol. Current fermentative H2 and ethanol yields, however, are below theoretical maxima, vary greatly among organisms, and depend on the extent of metabolic pathways utilized. For fermentative H2 and/or ethanol production to become practical, biofuel yields must be increased. We performed a comparative meta-analysis of (i reported end-product yields, and (ii genes encoding pyruvate metabolism and end-product synthesis pathways to identify suitable biomarkers for screening a microorganism’s potential of H2 and/or ethanol production, and to identify targets for metabolic engineering to improve biofuel yields. Our interest in H2 and/or ethanol optimization restricted our meta-analysis to organisms with sequenced genomes and limited branched end-product pathways. These included members of the Firmicutes, Euryarchaeota, and Thermotogae. Results Bioinformatic analysis revealed that the absence of genes encoding acetaldehyde dehydrogenase and bifunctional acetaldehyde/alcohol dehydrogenase (AdhE in Caldicellulosiruptor, Thermococcus, Pyrococcus, and Thermotoga species coincide with high H2 yields and low ethanol production. Organisms containing genes (or activities for both ethanol and H2 synthesis pathways (i.e. Caldanaerobacter subterraneus subsp. tengcongensis, Ethanoligenens harbinense, and Clostridium species had relatively uniform mixed product patterns. The absence of hydrogenases in Geobacillus and Bacillus species did not confer high ethanol production, but rather high lactate production. Only Thermoanaerobacter pseudethanolicus produced relatively high ethanol and low H2 yields. This may be attributed to the presence of genes encoding proteins that promote NADH production. Lactate dehydrogenase and pyruvate:formate lyase are not conducive for ethanol and/or H2 production. While the type(s of

  3. Acetate enhances startup of a H2-producing microbial biocathode

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    Jeremiasse, A.W.; Hamelers, H.V.M.; Croese, E.; Buisman, C.J.N.

    2012-01-01

    H2 can be produced from organic matter with a microbial electrolysis cell (MEC). To decrease MEC capital costs, a cathode is needed that is made of low-cost material and produces H2 at high rate. A microbial biocathode is a low-cost candidate, but suffers from a long startup and a low H2 production

  4. Chemiluminescent Detection of Enzymatically Produced H2S

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    Bailey, T. Spencer; Pluth, Michael D.

    2015-01-01

    Hydrogen sulfide (H2S) has emerged as an important biological signaling molecule. To better understand the multifaceted biological roles of H2S, the development of selective and sensitive biocompatible assays for H2S is becoming increasingly important. Motivated by these challenges, our laboratory is developing new methods to further detect and monitor biological H2S. Here, we describe in detail our recent advances in the development and the use of chemiluminescence-based H2S sensors to assist other investigators with use of these chemical tools. We highlight the use of these tools use by displaying their selectivity and high sensitivity toward H2S and provide examples of assays we have developed to detect enzymatically produced H2S. PMID:25725517

  5. Identification of H2S3 and H2S produced by 3-mercaptopyruvate sulfurtransferase in the brain.

    Science.gov (United States)

    Kimura, Yuka; Toyofuku, Yukiko; Koike, Shin; Shibuya, Norihiro; Nagahara, Noriyuki; Lefer, David; Ogasawara, Yuki; Kimura, Hideo

    2015-10-06

    Hydrogen polysulfides (H2Sn) have a higher number of sulfane sulfur atoms than hydrogen sulfide (H2S), which has various physiological roles. We recently found H2Sn in the brain. H2Sn induced some responses previously attributed to H2S but with much greater potency than H2S. However, the number of sulfur atoms in H2Sn and its producing enzyme were unknown. Here, we detected H2S3 and H2S, which were produced from 3-mercaptopyruvate (3 MP) by 3-mercaptopyruvate sulfurtransferase (3MST), in the brain. High performance liquid chromatography with fluorescence detection (LC-FL) and tandem mass spectrometry (LC-MS/MS) analyses showed that H2S3 and H2S were produced from 3 MP in the brain cells of wild-type mice but not 3MST knockout (3MST-KO) mice. Purified recombinant 3MST and lysates of COS cells expressing 3MST produced H2S3 from 3 MP, while those expressing defective 3MST mutants did not. H2S3 was localized in the cytosol of cells. H2S3 was also produced from H2S by 3MST and rhodanese. H2S2 was identified as a minor H2Sn, and 3 MP did not affect the H2S5 level. The present study provides new insights into the physiology of H2S3 and H2S, as well as novel therapeutic targets for diseases in which these molecules are involved.

  6. Chemiluminescent Detection of Enzymatically Produced H2S

    OpenAIRE

    Bailey, T. Spencer; Pluth, Michael D.

    2015-01-01

    Hydrogen sulfide (H2S) has emerged as an important biological signaling molecule. To better understand the multifaceted biological roles of H2S, the development of selective and sensitive biocompatible assays for H2S is becoming increasingly important. Motivated by these challenges, our laboratory is developing new methods to further detect and monitor biological H2S. Here, we describe in detail our recent advances in the development and the use of chemiluminescence-based H2S sensors to assis...

  7. The stable isotopic signature of biologically produced molecular hydrogen (H2

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    T. Röckmann

    2012-10-01

    Full Text Available Biologically produced molecular hydrogen (H2 is characterised by a very strong depletion in deuterium. Although the biological source to the atmosphere is small compared to photochemical or combustion sources, it makes an important contribution to the global isotope budget of H2. Large uncertainties exist in the quantification of the individual production and degradation processes that contribute to the atmospheric budget, and isotope measurements are a tool to distinguish the contributions from the different sources. Measurements of δ D from the various H2 sources are scarce and for biologically produced H2 only very few measurements exist. Here the first systematic study of the isotopic composition of biologically produced H2 is presented. In a first set of experiments, we investigated δ D of H2 produced in a biogas plant, covering different treatments of biogas production. In a second set of experiments, we investigated pure cultures of several H2 producing microorganisms such as bacteria or green algae. A Keeling plot analysis provides a robust overall source signature of δ D = −712‰ (±13‰ for the samples from the biogas reactor (at 38 °C, δ DH2O= +73.4‰, with a fractionation constant ϵH2-H2O of −689‰ (±20‰ between H2 and the water. The five experiments using pure culture samples from different microorganisms give a mean source signature of δ D = −728‰ (±28‰, and a fractionation constant ϵH2-H2O of −711‰ (±34‰ between H2 and the water. The results confirm the massive deuterium depletion of biologically produced H2 as was predicted by the calculation of the thermodynamic fractionation factors for hydrogen exchange between H2 and water vapour. Systematic errors in the isotope scale are difficult to assess in the absence of international standards for δ D of H2. As expected for a thermodynamic equilibrium, the fractionation factor is temperature dependent, but largely independent of the

  8. Validation of the H2S method to detect bacteria of fecal origin by cultured and molecular methods.

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    McMahan, Lanakila; Devine, Anthony A; Grunden, Amy M; Sobsey, Mark D

    2011-12-01

    Using biochemical and molecular methods, this research determined whether or not the H(2)S test did correctly identify sewage-contaminated waters by being the first to use culturing and molecular methods to identify the types and numbers of fecal indicator organisms, pathogens, and other microbes present in sewage samples with positive H(2)S test results. For the culture-based method, samples were analyzed for the presence of fecal bacteria by spread plating the sewage sample onto differential and selective media for Aeromonas spp., Escherichia coli, sulfite-reducing clostridia, H(2)S-producing bacteria, and Salmonella/Shigella spp. The isolates were then: (1) tested to determine whether they were H(2)S-producing organisms and (2) identified to the genus and species level using biochemical methods. The molecular method used to characterize the microbial populations of select samples was terminal restriction fragment length polymorphisms. These experiments on sewage provided evidence that positive H(2)S tests consistently contained fecal bacteria and pathogens. There were strong relationships of agreement between the organisms identified by both methods tested. This study is an important advance in microbial water quality detection since it is focused on the evaluation of a novel, low-cost, water microbiology test that has the potential to provide millions of people worldwide access to water quality detection technology. Of prime consideration in evaluating water quality tests is the determination of the test's accuracy and specificity, and this article is a fundamental step in providing that information.

  9. H2-saturation of high affinity H2-oxidizing bacteria alters the ecological niche of soil microorganisms unevenly among taxonomic groups.

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    Piché-Choquette, Sarah; Tremblay, Julien; Tringe, Susannah G; Constant, Philippe

    2016-01-01

    Soil microbial communities are continuously exposed to H2 diffusing into the soil from the atmosphere. N2-fixing nodules represent a peculiar microniche in soil where H2 can reach concentrations up to 20,000 fold higher than in the global atmosphere (0.530 ppmv). In this study, we investigated the impact of H2 exposure on soil bacterial community structure using dynamic microcosm chambers simulating soil H2 exposure from the atmosphere and N2-fixing nodules. Biphasic kinetic parameters governing H2 oxidation activity in soil changed drastically upon elevated H2 exposure, corresponding to a slight but significant decay of high affinity H2-oxidizing bacteria population, accompanied by an enrichment or activation of microorganisms displaying low-affinity for H2. In contrast to previous studies that unveiled limited response by a few species, the relative abundance of 958 bacterial ribotypes distributed among various taxonomic groups, rather than a few distinct taxa, was influenced by H2 exposure. Furthermore, correlation networks showed important alterations of ribotype covariation in response to H2 exposure, suggesting that H2 affects microbe-microbe interactions in soil. Taken together, our results demonstrate that H2-rich environments exert a direct influence on soil H2-oxidizing bacteria in addition to indirect effects on other members of the bacterial communities.

  10. Diversity and Characterization of Potential H2-Dependent Fe(Ⅲ)-Reducing Bacteria in Paddy Soils

    Institute of Scientific and Technical Information of China (English)

    LI Hui-Juan; PENG Jing-Jing; LI Hong-Bo

    2012-01-01

    Microbial ferric iron reduction,with organic carbon or hydrogen as the electron donor,is one of the most important biogeochemical processes in anoxic paddy soils; however,the diversity and community structure of hydrogen-dependent dissimilatory iron-reducers remain unknown.Potential H2-dependent Fe(Ⅲ)-reducing bacteria in paddy soils were explored using enrichment cultures with ferrihydrite or goethite as the electron acceptor and hydrogen as the electron donor.Terminal restriction fragment length polymorphism (T-RFLP) analysis and cloning/sequencing were conducted to reveal bacterial comnunity structure.Results showed that Geobacter and Clostridium were the dominant bacteria in the enrichment cultures.Fe(Ⅲ) oxide mineral phases showed a strong effect on the community structure; Geobacter and Clostridium were dominant in the ferrihydrite treatment,while Clostridium spp were dominant in the goethite treatment.These suggested that H2-dependent Fe(Ⅲ)-reducing bacteria might be widely distributed in paddy soils and that besides Geobacter,Clostridium spp.might also be an important group of H2-dependent Fe(Ⅲ)-reducing microorganisms.

  11. The stable isotopic signature of biologically produced molecular hydrogen (H2)

    NARCIS (Netherlands)

    Walter, S.; Laukenmann, S.; Stams, A.J.M.; Vollmer, M.K.; Gleixner, G.; Roeckmann, T.

    2012-01-01

    Biologically produced molecular hydrogen (H2) is characterised by a very strong depletion in deuterium. Although the biological source to the atmosphere is small compared to photochemical or combustion sources, it makes an important contribution to the global isotope budget of H2. Large

  12. The H2S Donor NaHS Changes the Expression Pattern of H2S-Producing Enzymes after Myocardial Infarction.

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    Li, Na; Wang, Ming-Jie; Jin, Sheng; Bai, Ya-Dan; Hou, Cui-Lan; Ma, Fen-Fen; Li, Xing-Hui; Zhu, Yi-Chun

    2016-01-01

    Aims. To examine the expression patterns of hydrogen sulphide- (H2S-) producing enzymes in ischaemic heart tissue and plasma levels of H2S after 2 weeks of NaHS treatment after myocardial infarction (MI) and to clarify the role of endogenous H2S in the MI process. Results. After MI surgery, 2 weeks of treatment with the H2S donor NaHS alleviated ischaemic injury. Meanwhile, in ischemia myocardium, three H2S-producing enzymes, cystathionine γ-lyase (CSE), cystathionine-β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MST) significantly increased. Plasma H2S levels were also elevated. In vitro, NaHS treatment protected cardiomyocytes from hypoxic injury and raised CBS levels in a concentration-dependent manner. Different from in vivo results, however, CSE or 3-MST expression did not change. NaHS treatment increased the activity of CSE/CBS but not of 3-MST. When CSE was either knocked down (in vitro) or knocked out (in vivo), H2S levels significantly decreased, which subsequently exacerbated the ischaemic injury. Meanwhile, the expressions of CBS and 3-MST increased due to compensation. Conclusions. Exogenous H2S treatment changed the expressions of three H2S-producing enzymes and H2S levels after MI, suggesting a new and indirect regulatory mechanism for H2S production and its contribution to cardiac protection. Endogenous H2S plays an important role in protecting ischaemic tissue after MI.

  13. Possibilities of CO and H2 Contents Change in the Syngas Produced by Biomass Gasification

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    Jan JANŠA

    2015-06-01

    Full Text Available Thermal gasification is an advanced technology to convert purposefully grown or waste ligno-cellulosic biomass into calorific gas. Increasing the content of CO and H2 in the product gas is important for the further use of the gas in technologies for power generation. This article describes the process of gasification and specifies parameters that determine the content of CO and H2 in the produced gas.

  14. Chryseobacterium indologenes, novel mannanase-producing bacteria

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    Surachai Rattanasuk

    2009-10-01

    Full Text Available Mannanase is a mannan degrading enzyme which is produced by microorganisms, including bacteria. This enzyme can be used in many industrial processes as well as for improving the quality of animal feeds. The aim of the present study was toscreen and characterize the mannanase-producing bacteria. Two genera of bacteria were isolated from Thai soil samples,fermented coconut, and fertilizer. Screening was carried out on agar plates containing mannan stained with iodine solution.The bacteria were identified by partial 16S rRNA gene sequence, biochemical test and morphology, respectively. The mannanase activity was determined by zymogram and DNS method. Two strains of bacteria with mannanase activity were identified as Bacillus and Chryseobacterium. This is the first report of mannanase-producing Chryseobacterium.

  15. The stable isotopic signature of biologically produced molecular hydrogen (H2)

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    Walter, S.; Laukenmann, S.; Stams, A.J.M.; Vollmer, M.K.; Gleixner, G.; Roeckmann, T.|info:eu-repo/dai/nl/304838233

    2011-01-01

    Biologically produced molecular hydrogen (H2) is characterized by a very strong depletion in deuterium. Although the biological source to the atmosphere is small compared to photochemical or combustion sources, it makes an important contribution to the global isotope budget of molecular hydrogen

  16. Do bacteria, not fish, produce 'fish kairomone'?

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    Ringelberg, J.; Van Gool, E.

    1998-01-01

    Fish-associated chemicals enhance phototactic downward swimming in Daphnia. If perch were treated with the antibiotic ampicillin, this enhancement was significantly decreased. Therefore, not fish, but bacteria associated with fish, seem to produce this kairomone. [KEYWORDS: Diel vertical migration;

  17. Exopolysaccharides produced by lactic acid bacteria

    NARCIS (Netherlands)

    Caggianiello, Graziano; Kleerebezem, Michiel; Spano, Giuseppe

    2016-01-01

    A wide range of lactic acid bacteria (LAB) is able to produce capsular or extracellular polysaccharides, with various chemical compositions and properties. Polysaccharides produced by LAB alter the rheological properties of the matrix in which they are dispersed, leading to typically viscous and

  18. [Bacteriocins produced by lactic acid bacteria].

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    Bilková, Andrea; Sepova, Hana Kinová; Bilka, Frantisek; Balázová, Andrea

    2011-04-01

    Lactic acid bacteria comprise several genera of gram-positive bacteria that are known for the production of structurally different antimicrobial substances. Among them, bacteriocins are nowadays in the centre of scientific interest. Bacteriocins, proteinaceous antimicrobial substances, are produced ribosomally and have usually a narrow spectrum of bacterial growth inhibition. According to their structure and the target of their activity, they are divided into four classes, although there are some suggestions for a renewed classification. The most interesting and usable class are lantibiotics. They comprise the most widely commercially used and well examined bacteriocin, nisin. The non-pathogenic character of lactic acid bacteria is advantageous for using their bacteriocins in food preservation as well as in feed supplements or in veterinary medicine.

  19. Identification of Shewanella baltica as the most important H2S-producing species during iced storage of danish marine fish

    DEFF Research Database (Denmark)

    Vogel, Birte Fonnesbech; Venkateswaran, K.; Satomi, M.

    2005-01-01

    Shewanella putrefaciens has been considered the main spoilage bacteria of low-temperature stored marine seafood. However, psychrotropic Shewanella have been reclassified during recent years, and the purpose of the present study was to determine whether any of the new Shewanella species...... are important in fish spoilage. More than 500 H2S-producing strains were isolated from iced stored marine fish (cod, plaice, and flounder) caught in the Baltic Sea during winter or summer time. All strains were identified as Shewanella species by phenotypic tests. Different Shewanella species were present...... on newly caught fish. During the warm summer months the mesophilic human pathogenic S. algae dominated the H2S-producing bacterial population. After iced storage, a shift in the Shewanella species was found, and most of the H2S-producing strains were identified as S. baltica. The 16S rRNA gene sequence...

  20. Clostridium amylolyticum sp. nov., isolated from H2-producing UASB granules.

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    Song, Lei; Dong, Xiuzhu

    2008-09-01

    A Gram-stain-positive, strictly anaerobic, mesophilic, amylolytic, rod-shaped bacterium, designated strain SW408(T), was isolated from a laboratory-scale H(2)-producing upflow anaerobic sludge blanket reactor. The strain grew at 24-45 degrees C (no growth at or below 22 degrees C or at or above 47 degrees C), with optimum growth at 37 degrees C. The pH range for growth was 4.0-9.0 (no growth at or below pH 3.6 or at or above pH 9.3), with optimum growth at pH 7.0. Starch, cellobiose, glucose, fructose, galactose, lactose, maltose, mannose, ribose and sucrose supported growth. The major end products from glucose fermentation were ethanol, acetate, hydrogen and carbon dioxide. Abundant H(2) was produced from starch fermentation. The DNA G+C content was 33.1 mol% (T(m) method). Phylogenetic analysis based on 16S rRNA gene sequence analysis showed that the bacterium represents a previously unrecognized species within Clostridium rRNA cluster I and is most closely related to the type strain of Clostridium frigidicarnis (94.9% similarity). On the basis of phenotypic, genotypic and phylogenetic characteristics, strain SW408(T) was identified as a representative of a novel species of the genus Clostridium, for which the name Clostridium amylolyticum sp. nov. is proposed. The type strain is SW408(T) (=JCM 14823(T)=AS 1.5069(T)=CGMCC 1.5069(T)).

  1. Implications from distinct sulfate-reducing bacteria populations between cattle manure and digestate in the elucidation of H2S production during anaerobic digestion of animal slurry.

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    St-Pierre, Benoit; Wright, André-Denis G

    2017-07-01

    Biogas produced from the anaerobic digestion of animal slurry consists mainly of methane (CH4) and carbon dioxide (CO2), but also includes other minor gases, such as hydrogen sulfide (H2S). Since it can act as a potent corrosive agent and presents a health hazard even at low concentrations, H2S is considered an undesirable by-product of anaerobic digestion. Sulfate-reducing bacteria (SRBs) have been identified as the main biological source of H2S in a number of natural, biological, and human-made habitats, and thus represent likely candidate microorganisms responsible for the production of H2S in anaerobic manure digesters. Phylogenetically, SRBs form a divergent group of bacteria that share a common anaerobic respiration pathway that allows them to use sulfate as a terminal electron acceptor. While the composition and activity of SRBs have been well documented in other environments, their metabolic potential remains largely uncharacterized and their populations poorly defined in anaerobic manure digesters. In this context, a combination of in vitro culture-based studies and DNA-based approaches, respectively, were used to gain further insight. Unexpectedly, only low to nondetectable levels of H2S were produced by digestate collected from a manure biogas plant documented to have persistently high concentrations of H2S in its biogas (2000-3000 ppm). In contrast, combining digestate with untreated manure (a substrate with comparatively lower sulfate and SRB cell densities than digestate) was found to produce elevated H2S levels in culture. While a 16S rRNA gene-based community composition approach did not reveal likely candidate SRBs in digestate or untreated manure, the use of the dsrAB gene as a phylogenetic marker provided more insight. In digestate, the predominant SRBs were found to be uncharacterized species likely belonging to the genus Desulfosporosinus (Peptococcaceae, Clostridiales, Firmicutes), while Desulfovibrio-related SRBs (Desulfovibrionaceae

  2. 一株红色素产生菌H2的初步鉴定%Preliminary Identification of A Strain H2 Producing Red Pigments

    Institute of Scientific and Technical Information of China (English)

    赵昌会

    2012-01-01

    A bacterial strain producing red pigments was isolated from marine mud,its biochemical and physiological characteristics,16S rDNA sequence were investigated.The result showed that the strain was Gram negative,could produce H2S,2,3-butanediol,peroxidase,gelatinase,the growth temperature was 4~37℃.It could use maltose,cellobiase,glycerol,D-glucose,D-fructose,trehalose,sucrose,D-mannitol etc.as carbon resource,and could use peptone,yeast extract and beef extract as nitrogen resource.The strain H2 was identified as Serratia marcescens by 16S rDNA,and phylogenetic trees were constructed by neighbor joining.%从海泥中分离纯化得到1株产红色素细菌,对该菌进行生理生化分析和16SrDNA鉴定。结果表明:该菌为革兰氏阴性,H2S、V.P.、酶触及明胶液化试验呈阳性,可在4~37℃下生长。可利用的碳源有麦芽糖、纤维二糖、甘油、D-葡萄糖、D-果糖、海藻糖、蔗糖及D-甘露醇等,可利用的氮源有蛋白胨、酵母膏和牛肉膏等;16SrDNA鉴定为Serratia marcescens,并建立了H2系统发育树。

  3. Simultaneous inhibition of sulfate-reducing bacteria, removal of H2S and production of rhamnolipid by recombinant Pseudomonas stutzeri Rhl: Applications for microbial enhanced oil recovery.

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    Zhao, Feng; Zhou, Ji-Dong; Ma, Fang; Shi, Rong-Jiu; Han, Si-Qin; Zhang, Jie; Zhang, Ying

    2016-05-01

    Sulfate-reducing bacteria (SRB) are widely existed in oil production system, and its H2S product inhibits rhamnolipid producing bacteria. In-situ production of rhamnolipid is promising for microbial enhanced oil recovery. Inhibition of SRB, removal of H2S and production of rhamnolipid by recombinant Pseudomonas stutzeri Rhl were investigated. Strain Rhl can simultaneously remove S(2-) (>92%) and produce rhamnolipid (>136mg/l) under S(2-) stress below 33.3mg/l. Rhl reduced the SRB numbers from 10(9) to 10(5)cells/ml, and the production of H2S was delayed and decreased to below 2mg/l. Rhl also produced rhamnolipid and removed S(2-) under laboratory simulated oil reservoir conditions. High-throughput sequencing data demonstrated that addition of strain Rhl significantly changed the original microbial communities of oilfield production water and decreased the species and abundance of SRB. Bioaugmentation of strain Rhl in oilfield is promising for simultaneous control of SRB, removal of S(2-) and enhance oil recovery. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Genome-wide primary transcriptome analysis of H2-producing archaeon Thermococcus onnurineus NA1

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    Cho, Suhyung; Kim, Min-Sik; Jeong, Yujin; Lee, Bo-Rahm; Lee, Jung-Hyun; Kang, Sung Gyun; Cho, Byung-Kwan

    2017-01-01

    In spite of their pivotal roles in transcriptional and post-transcriptional processes, the regulatory elements of archaeal genomes are not yet fully understood. Here, we determine the primary transcriptome of the H2-producing archaeon Thermococcus onnurineus NA1. We identified 1,082 purine-rich transcription initiation sites along with well-conserved TATA box, A-rich B recognition element (BRE), and promoter proximal element (PPE) motif in promoter regions, a high pyrimidine nucleotide content (T/C) at the −1 position, and Shine-Dalgarno (SD) motifs (GGDGRD) in 5′ untranslated regions (5′ UTRs). Along with differential transcript levels, 117 leaderless genes and 86 non-coding RNAs (ncRNAs) were identified, representing diverse cellular functions and potential regulatory functions under the different growth conditions. Interestingly, we observed low GC content in ncRNAs for RNA-based regulation via unstructured forms or interaction with other cellular components. Further comparative analysis of T. onnurineus upstream regulatory sequences with those of closely related archaeal genomes demonstrated that transcription of orthologous genes are initiated by highly conserved promoter sequences, however their upstream sequences for transcriptional and translational regulation are largely diverse. These results provide the genetic information of T. onnurineus for its future application in metabolic engineering. PMID:28216628

  5. Soil carbon content and relative abundance of high affinity H2-oxidizing bacteria predict atmospheric H2 soil uptake activity better than soil microbial community composition

    NARCIS (Netherlands)

    Khdhiri, Mondher; Hesse, Laura; Popa, Maria Elena; Quiza, Liliana; Lalonde, Isabelle; Meredith, Laura K.; Röckmann, Thomas; Constant, Philippe

    2015-01-01

    Soil-atmosphere exchange of H2 is controlled by gas diffusion and the microbial production and oxidation activities in soil. Among these parameters, the H2 oxidation activity catalyzed by soil microorganisms harboring high affinity hydrogenase is the most difficult variable to parameterize because i

  6. Producing baryons from neutralinos in small H2 clumps over cosmological ages

    CERN Document Server

    Giraud, Edmond

    2012-01-01

    Extreme scattering events in quasars suggest the existence of dark H2 clumps of mass $\\rm \\sim 10^{-3} sim M_\\odot$ and size $\\rm \\sim 10 AU$. Such H2 clumps are extremely dense compared to WIMPs clumps of the same mass obtained by N-body simulations. A WIMP clump seeded by an H2 clump experiences a first infall during which its density increases by $\\rm 10^6$ in $\\rm \\sim 1 Myr$. In this poster I begin to explore the phenomenology of mixed clumps made with H2 and WIMPs. Molecular clouds built with clumps are efficient machines to transform smooth distributions of WIMPs into concentrated networks. If WIMPs are neutralinos trapped in such moleular clouds, they may either enrich the baryon sector over cosmological ages, or remain mixed with cold H2 clouds until the clumps evaporate either by collision or by stellar UV heating. One of the main drawbacks of CDM profiles, their overly dense cores, is briefly revisited in this context.

  7. Improvement of H2 yield of Fermentative Bacteria by Gene Manipulation

    Energy Technology Data Exchange (ETDEWEB)

    Makiko Harada; Takashi Kaneko; Shigeharu Tanisho [Department of Environmental and Information Sciences, Yokohama National University Hodogaya-Ku, Yokohama 240-8501, (Japan)

    2006-07-01

    Two method were proposed in this paper. One is to destroy the NADH dehydrogenase complex in the electron transport chain of a facultative anaerobic bacterium Enterobacter aerogenes and the other is to disrupt the butyrate producing pathway of a strict anaerobic bacterium Clostridium butyricum. In case of E. aerogenes, one of the 14 membrane-bound NADH dehydrogenases, nuoG, is targeted to destroy. In case of C. butyricum, function of thiolase is targeted to disrupt. (authors)

  8. Potential for microbial H2 and metal transformations associated with novel bacteria and archaea in deep terrestrial subsurface sediments.

    Science.gov (United States)

    Hernsdorf, Alex W; Amano, Yuki; Miyakawa, Kazuya; Ise, Kotaro; Suzuki, Yohey; Anantharaman, Karthik; Probst, Alexander; Burstein, David; Thomas, Brian C; Banfield, Jillian F

    2017-08-01

    Geological sequestration in deep underground repositories is the prevailing proposed route for radioactive waste disposal. After the disposal of radioactive waste in the subsurface, H2 may be produced by corrosion of steel and, ultimately, radionuclides will be exposed to the surrounding environment. To evaluate the potential for microbial activities to impact disposal systems, we explored the microbial community structure and metabolic functions of a sediment-hosted ecosystem at the Horonobe Underground Research Laboratory, Hokkaido, Japan. Overall, we found that the ecosystem hosted organisms from diverse lineages, including many from the phyla that lack isolated representatives. The majority of organisms can metabolize H2, often via oxidative [NiFe] hydrogenases or electron-bifurcating [FeFe] hydrogenases that enable ferredoxin-based pathways, including the ion motive Rnf complex. Many organisms implicated in H2 metabolism are also predicted to catalyze carbon, nitrogen, iron and sulfur transformations. Notably, iron-based metabolism is predicted in a novel lineage of Actinobacteria and in a putative methane-oxidizing ANME-2d archaeon. We infer an ecological model that links microorganisms to sediment-derived resources and predict potential impacts of microbial activity on H2 consumption and retardation of radionuclide migration.

  9. Distribution of urease producing bacteria in the

    African Journals Online (AJOL)

    higher proportion of bacteria associated with the caecal wall. (63%) were facultative .... Of even more importance is the role that the domestic rabbit can and ... Until more is known about digestion of plant foods in the monogastric herbivore ...

  10. Individually and Synergistic Degradation of Hydrocarbons by Biosurfactant Producing Bacteria

    Directory of Open Access Journals (Sweden)

    Amirarsalan Kavyanifard

    2016-02-01

    Full Text Available Background: Increasing worldwide contamination with hydrocarbons has urged environmental remediation using biological agents such as bacteria. Our goal here was to study the phylogenetic relationship of two crude oil degrader bacteria and investigation of their ability to degrade hydrocarbons. Materials and Methods: Phylogenetic relationship of isolates was determined using morphological and biochemical characteristics and 16S rDNA gene sequencing. Optimum conditions of each isolate for crude oil degradation were investigated using one factor in time method. The rate of crude oil degradation by individual and consortium bacteria was assayed via Gas chromatography–mass spectrometry (GC-MS analysis. Biosurfactant production was measured by Du Noüy ring method using Krüss-K6 tensiometer. Results: The isolates were identified as Dietzia cinnamea KA1 and Dietzia cinnamea AP and clustered separately, while both are closely related to each other and with other isolates of Dietzia cinnamea. The optimal conditions for D. cinnamea KA1 were 35°C, pH9.0, 510 mM NaCl, and minimal requirement of 46.5 mM NH4Cl and 2.10 mM NaH2PO4. In the case of D. cinnamea AP, the values were 30°C, pH8.0, 170 mM NaCl, and minimal requirement of 55.8 mM NH4Cl and 2.10 mM NaH2PO4, respectively. Gas chromatography – Mass Spectroscopy (GC-MS analysis showed that both isolates were able to utilize various crude oil compounds, but D. cinnamea KA1 was more efficient individually and consortium of isolates was the most. The isolates were able to grow and produce biosurfactant when cultured in MSM supplemented with crude oil and optimization of MSM conditions lead to increase in biosurfactant production. Conclusion: To the best of our knowledge this is the first report of synergistic relationship between two strains of D. cinnamea in biodegradation of crude oil components, including poisonous and carcinogenic compound in a short time.

  11. Toxicity of hydrogen peroxide produced by electroplated coatings to pathogenic bacteria.

    Science.gov (United States)

    Zhao, Z H; Sakagami, Y; Osaka, T

    1998-05-01

    The ability of various electroplated coatings (cobalt, zinc, copper, and cobalt-containing alloys of nickel, zinc, chromium, etc.) to inhibit the growth of pathogenic bacteria (Gram-positive bacteria Enterococcus faecalis and methicillin-resistant Staphylococcus aureus and Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae) was determined by a drop-method antibacterial experiment. The amounts of H2O2 produced and metal ions dissolved from the surfaces of various electroplated coatings were measured and it was found that the inhibitory ability of coatings corresponded to the amounts of H2O2 produced. The more significant the inhibition of the coating to bacterial growth, the greater the amount of H2O2 production. In addition, the bacterial survival rates on the surfaces of coatings were almost zero when H2O2 was produced in amounts greater than 10(-6) mmol/cm2. However, the dominant concentrations of metal ions dissolved from coatings were outside of the bacterial lethal range.

  12. Vacuum ultraviolet photolysis of hydrogenated amorphous carbons. III. Diffusion of photo-produced H2 as a function of temperature

    CERN Document Server

    Martín-Doménech, Rafael; Caro, Guillermo M Muñoz

    2016-01-01

    Hydrogenated amorphous carbon (a-C:H) has been proposed as one of the carbonaceous solids detected in the interstellar medium. Energetic processing of the a-C:H particles leads to the dissociation of the C-H bonds and the formation of hydrogen molecules and small hydrocarbons. Photo-produced H2 molecules in the bulk of the dust particles can diffuse out to the gas phase and contribute to the total H2 abundance. We have simulated this process in the laboratory with plasma-produced a-C:H and a-C:D analogs under astrophysically relevant conditions to investigate the dependence of the diffusion as a function of temperature. Plasma-produced a-C:H analogs were UV-irradiated using a microwave-discharged hydrogen flow lamp. Molecules diffusing to the gas-phase were detected by a quadrupole mass spectrometer, providing a measurement of the outgoing H2 or D2 flux. By comparing the experimental measurements with the expected flux from a one-dimensional diffusion model, a diffusion coefficient D could be derived for expe...

  13. Novel Simplified and Rapid Method for Screening and Isolation of Polyunsaturated Fatty Acids Producing Marine Bacteria

    Directory of Open Access Journals (Sweden)

    Ashwini Tilay

    2012-01-01

    Full Text Available Bacterial production of polyunsaturated fatty acids (PUFAs is a potential biotechnological approach for production of valuable nutraceuticals. Reliable method for screening of number of strains within short period of time is great need. Here, we report a novel simplified method for screening and isolation of PUFA-producing bacteria by direct visualization using the H2O2-plate assay. The oxidative stability of PUFAs in growing bacteria towards added H2O2 is a distinguishing characteristic between the PUFAs producers (no zone of inhibition and non-PUFAs producers (zone of inhibition by direct visualization. The confirmation of assay results was performed by injecting fatty acid methyl esters (FAMEs produced by selected marine bacteria to Gas Chromatography-Mass Spectrometry (GCMS. To date, this assay is the most effective, inexpensive, and specific method for bacteria producing PUFAs and shows drastically reduction in the number of samples thus saves the time, effort, and cost of screening and isolating strains of bacterial PUFAs producers.

  14. Metabolic adaptations in a H2 producing heterocyst-forming cyanobacterium: potentials and implications for biological engineering.

    Science.gov (United States)

    Ekman, Martin; Ow, Saw Yen; Holmqvist, Marie; Zhang, Xiaohui; van Wagenen, Jon; Wright, Phillip C; Stensjö, Karin

    2011-04-01

    Nostoc punctiforme ATCC 29133 is a photoautotrophic cyanobacterium with the ability to fix atmospheric nitrogen and photoproduce hydrogen through the enzyme nitrogenase. The H(2) produced is reoxidized by an uptake hydrogenase. Inactivation of the uptake hydrogenase in N. punctiforme leads to increased H(2) release but unchanged rates of N(2) fixation, indicating redirected metabolism. System-wide understanding of the mechanisms of this metabolic redirection was obtained using complementary quantitative proteomic approaches, at both the filament and the heterocyst level. Of the total 1070 identified and quantified proteins, 239 were differentially expressed in the uptake hydrogenase mutant (NHM5) as compared to wild type. Our results indicate that the inactivation of uptake hydrogenase in N. punctiforme changes the overall metabolic equilibrium, affecting both oxygen reduction mechanisms in heterocysts as well as processes providing reducing equivalents for metabolic functions such as N(2) fixation. We identify specific metabolic processes used by NHM5 to maintain a high rate of N(2) fixation, and thereby potential targets for further improvement of nitrogenase based H(2) photogeneration. These targets include, but are not limited to, components of the oxygen scavenging capacity and cell envelope of heterocysts and proteins directly or indirectly involved in reduced carbon transport from vegetative cells to heterocysts.

  15. Quantifying within-household transmission of ESBL-producing bacteria

    NARCIS (Netherlands)

    Haverkate, Manon R; Platteel, Tamara N; Fluit, A C; Cohen Stuart, James W; Leverstein-van Hall, Maurine A; Thijsen, Steven F T; Scharringa, J.; Kloosterman, Fieke R C; Bonten, Marc J M; Bootsma, Martin C J

    OBJECTIVES: Patients can acquire extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae during hospitalisation and colonised patients may transmit these bacteria after discharge, most likely to household contacts. In this study, ESBL transmission was quantified in households. METHODS:

  16. Dopamine treatment attenuates acute kidney injury in a rat model of deep hypothermia and rewarming - The role of renal H2S-producing enzymes.

    Science.gov (United States)

    Dugbartey, George J; Talaei, Fatemeh; Houwertjes, Martin C; Goris, Maaike; Epema, Anne H; Bouma, Hjalmar R; Henning, Robert H

    2015-12-15

    Hypothermia and rewarming produces organ injury through the production of reactive oxygen species. We previously found that dopamine prevents hypothermia and rewarming-induced apoptosis in cultured cells through increased expression of the H2S-producing enzyme cystathionine β-Synthase (CBS). Here, we investigate whether dopamine protects the kidney in deep body cooling and explore the role of H2S-producing enzymes in an in vivo rat model of deep hypothermia and rewarming. In anesthetized Wistar rats, body temperature was decreased to 15°C for 3h, followed by rewarming for 1h. Rats (n≥5 per group) were treated throughout the procedure with vehicle or dopamine infusion, and in the presence or absence of a non-specific inhibitor of H2S-producing enzymes, amino-oxyacetic acid (AOAA). Kidney damage and renal expression of three H2S-producing enzymes (CBS, CSE and 3-MST) was quantified and serum H2S level measured. Hypothermia and rewarming induced renal damage, evidenced by increased serum creatinine, renal reactive oxygen species production, KIM-1 expression and influx of immune cells, which was accompanied by substantially lowered renal expression of CBS, CSE, and 3-MST and lowered serum H2S levels. Infusion of dopamine fully attenuated renal damage and maintained expression of H2S-producing enzymes, while normalizing serum H2S. AOAA further decreased the expression of H2S-producing enzymes and serum H2S level, and aggravated renal damage. Hence, dopamine preserves renal integrity during deep hypothermia and rewarming likely by maintaining the expression of renal H2S-producing enzymes and serum H2S. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Emergence and prevalence of non-H2S-producing Salmonella enterica serovar Senftenberg isolates belonging to novel sequence type 1751 in China.

    Science.gov (United States)

    Yi, Shengjie; Xie, Jing; Liu, Nan; Li, Peng; Xu, Xuebin; Li, Hao; Sun, Jichao; Wang, Jian; Liang, Beibei; Yang, Chaojie; Wang, Xu; Hao, Rongzhang; Wang, Ligui; Wu, Zhihao; Zhang, Jianmin; Wang, Yong; Huang, Liuyu; Sun, Yansong; Klena, John D; Meng, Jianghong; Qiu, Shaofu; Song, Hongbin

    2014-07-01

    Salmonella enterica serovar Senftenberg is a common nontyphoidal Salmonella serotype which causes human Salmonella infections worldwide. In this study, 182 S. Senftenberg isolates, including 17 atypical non-hydrogen sulfide (H2S)-producing isolates, were detected in China from 2005 to 2011. The microbiological and genetic characteristics of the non-H2S-producing and selected H2S-producing isolates were determined by using pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and clustered regularly interspaced short palindromic repeat (CRISPR) analysis. The phs operons were amplified and sequenced. The 17 non-H2S-producing and 36 H2S-producing isolates belonged to 7 sequence types (STs), including 3 new STs, ST1751, ST1757, and ST1758. Fourteen of the 17 non-H2S-producing isolates belonged to ST1751 and had very similar PFGE patterns. All 17 non-H2S-producing isolates had a nonsense mutation at position 1621 of phsA. H2S-producing and non-H2S-producing S. Senftenberg isolates were isolated from the same stool sample from three patients; isolates from the same patients displayed the same antimicrobial susceptibility, ST, and PFGE pattern but could be discriminated based on CRISPR spacers. Non-H2S-producing S. Senftenberg isolates belonging to ST1751 have been prevalent in Shanghai, China. It is possible that these emerging organisms will disseminate further, because they are difficult to detect. Thus, we should strengthen the surveillance for the spread of this atypical S. Senftenberg variant.

  18. Application of bacteriophages specific to hydrogen sulfide-producing bacteria in raw poultry by-products.

    Science.gov (United States)

    Gong, Chao; Liu, Xiaohua; Jiang, Xiuping

    2014-03-01

    Hydrogen sulfide-producing bacteria (SPB) can spoil raw animal materials and release harmful hydrogen sulfide (H2S) gas. The objective of this study was to apply a SPB-specific bacteriophage cocktail to control H2S production by SPB in different raw poultry by-products in the laboratory (20, 30, and 37°C) and greenhouse (average temperature 29 to 31°C, humidity 34.8 to 59.8%, and light intensity 604.8 Wm(2)) by simulating transportation and a rendering facility. The amount of H2S production was determined using either test strips impregnated with lead acetate or a H2S monitor. In the laboratory, phage treatment applied to fresh chicken meat inoculated with SPB, spoiled chicken meat, chicken guts, and chicken feathers reduced H2S production by approximately 25 to 69% at temperatures from 20 to 37°C. In the greenhouse, phage treatment achieved approximately a 30 to 85% reduction of H2S yield in chicken offal and feathers. Among all phage treatments, multiplicity of infection (MOI) of 100 exhibited the highest inhibitory activities against SPB on H2S production. Several factors such as initial SPB level, temperature, and MOI affect lytic activities of bacteriophages. Our study demonstrated that the phage cocktail is effective to reduce the production of H2S by SPB significantly in raw animal materials. This biological control method can control SPB in raw poultry by-products at ambient temperatures, leading to a safer working environment and high quality product with less nutrient degradation for the rendering industry.

  19. Reversion of stressed and unstressed hydrogen sulfide (H2S) producing strains of Salmonella in different media.

    Science.gov (United States)

    Salmonella can be difficult to assess and isolate in poultry feed due to uneven distribution and poor growth. Previous studies have shown that several strains of Salmonella can be affected by changes in environment, resulting in the growth of H2S-negative colonies. This is concerning, as H2S produ...

  20. Cantilever enhanced photoacoustic spectrometry: Quantitative analysis of the trace H2S produced by SF6 decomposition

    Science.gov (United States)

    Zhang, Xiaoxing; Cheng, Zheng; Li, Xin

    2016-09-01

    As one of the key characteristic components that result from sulfur hexafluoride (SF6) decomposition in SF6 gas-insulated equipment, hydrogen sulfide (H2S) can reflect the severity of the internal insulation faults and indicate whether or not such faults involve solid insulation material effectively. The decomposition of SF6 and its reaction with other impurities to form H2S are simulated in this study via Materials Studio. The simulation verifies that H2S is generated only when serious faults occur in the equipment; thus, the online monitoring of the trace H2S is highly necessary. To achieve a high detection accuracy and avoid cross interference, the spectral line R (8) of the H2S ν1 + ν2 + ν3 co-frequency absorption band is taken as the absorption line for the gas detection by online simulation based on the HITRAN on the Web. In addition, this study develops a cantilever-enhanced photoacoustic spectrometry trace gas detection platform and conducts experimental research on the quantitative detection of trace H2S/SF6 and H2S/N2. Experimental results show that the detection sensitivity of the detection platform to trace H2S under the background gas N2 and SF6 is 0.84 and 1.75 μL/L, respectively, and a strong linear relationship exists between the trace H2S concentration and its corresponding PA signal. Moreover, based on both the theoretical simulation and experiment, the influence of temperature and pressure on the detection platform is discussed and analyzed. The results indicate that the change in the PA signal amplitude decreases with an increase in the pressure or temperature of the PA cell, and the detection platform is more sensitive to pressure.

  1. 甲异羟肟酸-硝酸辐解产生的H_2和CO%H_2 and CO Produced by Radiolysis of HNO_3-FHA Solution

    Institute of Scientific and Technical Information of China (English)

    王锦花; 王生秀; 吴明红; 包伯荣; 吴君萍; 郑卫芳; 张生栋

    2009-01-01

    Formohydroxamic acid (FHA) is a new salt-free complexant which may be used in the reprocessing of spent nuclear fuel. This paper reports on the study of H_2 and CO produced by radiolysis of HNO_3-0.2 mol/L FHA. These analyses were performed by gas chromatography in which a packed 5(A) molsieves column and a thermal conductivity detector (TCD) were used. Argon was used as a carrier gas in the analysis of H_2, the temperature of column and TCD was 85 ℃ and 120 ℃ respectively; H_2 was used as a carrier gas in the analysis of CO, the temperature of column and TCD were 50 ℃ and 80 ℃ respectively. The results show that the volume fraction of H_2 increases with the dose, but decreases with the concentration of nitric acid. CO is only produced at high dose, and the volume fraction of CO is much lower than that of H_2. The volume fraction of CO increases with the dose. When the concentration of nitric acid is not more than 0.5 mol/L, the volume fraction of CO is lower than that produced by 0.2 mol/L FHA aqueous solution; when the concentration of nitric acid is no less than 1.0 mol/L, the volume fraction of CO is higher than that produced by 0.2 mol/L FHA aqueous solution, and the volume fraction of CO increases with the concentration of nitric acid.%甲异羟肟酸(FHA)是有望用于乏燃料后处理的新型无盐络合剂.用5(A)分子筛填充柱与热导池检测器(TCD)联用的气相色谱法研究了HNO_3-0.2 mol/L FHA辐解产生的H_2和CO.H_2的分析是以Ar作载气,柱温为85 ℃,TCD温度为120 ℃; CO的分析是以H_2作载气,柱温为50 ℃, TCD温度为80 ℃.研究结果表明,H_2的体积分数随剂量的增加而增大,随HNO_3浓度的增大而减小;CO只有在剂量很高时才产生,且其体积分数远比H_2低,CO的体积分数随剂量的增加而增加.当c(HNO_3)≤0.5 mol/L时,CO体积分数低于0.2 mol/L FHA水溶液辐解产生的CO,但当c(HNO_3)≥1.0 mol/L时,CO的体积分数大于0.2 mol/L FHA

  2. Genetic Approach for the Fast Discovery of Phenazine Producing Bacteria

    Directory of Open Access Journals (Sweden)

    Johannes F. Imhoff

    2011-05-01

    Full Text Available A fast and efficient approach was established to identify bacteria possessing the potential to biosynthesize phenazines, which are of special interest regarding their antimicrobial activities. Sequences of phzE genes, which are part of the phenazine biosynthetic pathway, were used to design one universal primer system and to analyze the ability of bacteria to produce phenazine. Diverse bacteria from different marine habitats and belonging to six major phylogenetic lines were investigated. Bacteria exhibiting phzE gene fragments affiliated to Firmicutes, Alpha- and Gammaproteobacteria, and Actinobacteria. Thus, these are the first primers for amplifying gene fragments from Firmicutes and Alphaproteobacteria. The genetic potential for phenazine production was shown for four type strains belonging to the genera Streptomyces and Pseudomonas as well as for 13 environmental isolates from marine habitats. For the first time, the genetic ability of phenazine biosynthesis was verified by analyzing the metabolite pattern of all PCR-positive strains via HPLC-UV/MS. Phenazine production was demonstrated for the type strains known to produce endophenazines, 2-hydroxy-phenazine, phenazine-1-carboxylic acid, phenazine-1,6-dicarboxylic acid, and chlororaphin as well as for members of marine Actinobacteria. Interestingly, a number of unidentified phenazines possibly represent new phenazine structures.

  3. Pigments produced by the bacteria belonging to the genus Arthrobacter

    OpenAIRE

    Sutthiwong, N.; Caro, Y.; Fouillaud, M.; Laurent, P.; Valla, A.; Dufossé, L.

    2013-01-01

    Poster communication, 7th International Congress of Pigments in Food – New technologies towards health, through colors, Novara, Italy, June 18-21, 2013.; International audience; Since several decades, pigments have been used as a taxonomic tool for the identification and classification of bacteria. Nowadays, pigment producing microorganisms have been also widely interested in scientific disciplines because of their biotechnological potential. With the growing interest in microbial pigments be...

  4. Occurrence of carbapenemase-producing bacteria in coastal recreational waters.

    Science.gov (United States)

    Montezzi, Lara Feital; Campana, Eloiza Helena; Corrêa, Laís Lisboa; Justo, Livia Helena; Paschoal, Raphael Paiva; da Silva, Isabel Lemos Vieira Dias; Souza, Maria do Carmo Maciel; Drolshagen, Marcia; Picão, Renata Cristina

    2015-02-01

    The spread of carbapenemase-producing Gram-negative rods is an emerging global problem. Although most infections due to carbapenemase producers are limited to healthcare institutions, reports of the occurrence of clinically relevant carbapenemase producers in sewage and polluted rivers are increasingly frequent. Polluted rivers flowing to oceans may contaminate coastal waters with multidrug-resistant bacteria, potentially threatening the safety of recreational activities in these locations. Here we assessed the occurrence of carbapenemase producers in water from touristic beaches located in Rio de Janeiro, Brazil, showing distinct pollution patterns. The presence of enterobacteria was noted, including the predominantly environmental genus Kluyvera spp., producing either Klebsiella pneumoniae carbapenemase (KPC) or Guyana extended-spectrum (GES)-type carbapenemases and often associated with quinolone resistance determinants. An Aeromonas sp. harbouring blaKPC and qnrS was also observed. These findings strengthen the role of aquatic matrices as reservoirs and vectors of clinically relevant antimicrobial-resistant bacteria, with potential to favour the spread of these resistance threats throughout the community. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  5. Effect of carbon dioxide and temperature on H2 producing cultures of the extreme thermophile, Caldicellulosiruptor saccharolyticus

    OpenAIRE

    van Niel, Ed; Martens, A.A.; Claassen, P.A.M.

    2004-01-01

    Carbon dioxide could replace nitrogen gas as stripping gas for the production of H2 by the extreme thermophile, Caldicellulosiruptor saccharolyticus, provided that the pH is kept below 7.0. Above this pH, ≥77 mM sodium bicarbonate will be introduced as an extra salt burden to the culture. High concentrations of sugars and salts contribute each to the inhibition of growth and H2 production, which is most probably due to the osmolality. As a consequence, using CO2 as stripping gas might lower t...

  6. Screening and isolation of halophilic bacteria producing industrially important enzymes

    Directory of Open Access Journals (Sweden)

    Sumit Kumar

    2012-12-01

    Full Text Available Halophiles are excellent sources of enzymes that are not only salt stable but also can withstand and carry out reactions efficiently under extreme conditions. The aim of the study was to isolate and study the diversity among halophilic bacteria producing enzymes of industrial value. Screening of halophiles from various saline habitats of India led to isolation of 108 halophilic bacteria producing industrially important hydrolases (amylases, lipases and proteases. Characterization of 21 potential isolates by morphological, biochemical and 16S rRNA gene analysis found them related to Marinobacter, Virgibacillus, Halobacillus, Geomicrobium, Chromohalobacter, Oceanobacillus, Bacillus, Halomonas and Staphylococcus genera. They belonged to moderately halophilic group of bacteria exhibiting salt requirement in the range of 3-20%. There is significant diversity among halophiles from saline habitats of India. Preliminary characterization of crude hydrolases established them to be active and stable under more than one extreme condition of high salt, pH, temperature and presence of organic solvents. It is concluded that these halophilic isolates are not only diverse in phylogeny but also in their enzyme characteristics. Their enzymes may be potentially useful for catalysis under harsh operational conditions encountered in industrial processes. The solvent stability among halophilic enzymes seems a generic novel feature making them potentially useful in non-aqueous enzymology.

  7. Characterization of protease-producing bacteria isolated from terasi

    Directory of Open Access Journals (Sweden)

    Novi Arfarita

    2016-03-01

    Full Text Available Total of 117 bacterial strains were isolated from terasi samples and 69% of isolates (71 could perform distinctive proteolytic activity that related to the ability to produce protease enzymes. Their proteolytic activity was further tested using spot incubation technique. Strain S4-5 has shown the highest activity then was selected for further tests in this study. Gram staining test showed that S4-5 is gram positive bacteria and able to grow under anaerobic condition. Based on API biochemical profiles, S4-5 strain bacteria was Bacillus licheniformis. Similarity test of genome sequence among Bacillus species from gene bank (EMBL Sequence Version with Bacillus spp., strain S4-5 had similarity with Bacillus licheniformis genome. The optimal pH of this strain was 6 whereas the optimum temperature for Bacillus licheniformis strain S4-5 was 37ºC.

  8. Alternative methodology for isolation of biosurfactant-producing bacteria

    Directory of Open Access Journals (Sweden)

    N. Krepsky

    Full Text Available Wide biosurfactant application on biorremediation is limited by its high production cost. The search for cheaper biossurfactant production alternatives has guided our study. The use of selective media containing sucrose (10 g.L-1 and Arabian Light oil (2 g.L-1 as carbon sources showed to be effective to screen and maintain biosurfactant-producing consortia isolated from mangrove hydrocarbon-contaminated sediment. The biosurfactant production was assayed by kerosene, gasoline and Arabian Light Emulsification activity and the bacterial growth curve was determined by bacterial quantification. The parameters analyzed for biosurfactant production were the growth curve, salinity concentration, flask shape and oxygenation. All bacteria consortia screened were able to emulsify the petroleum derivatives tested. Biosurfactant production increased according to the incubation time; however the type of emulsification (non-aqueous phase or aqueous phase did not change with time but with the compound tested. The methodology was able to isolate biosurfactant-producing consortia from superficial mangrove sediment contaminated by petroleum hydrocarbons and was recommended for selection of biosurfactant producing bacteria in tropical countries with low financial resources.

  9. Utilization of bacteriocin-producing bacteria in dairy products

    Directory of Open Access Journals (Sweden)

    Matěj Patrovský

    2016-07-01

    Full Text Available Lactic acid bacteria have been used since ancient times for food preparation and for bio-conservation by fermentation. Selected strains are capable of producing antimicrobial peptides - bacteriocins, which can be natural preservatives, especially in products with short shelf lives. The present study is focused on inhibitory effects of the bacteriocin-producing bacteria strains Enterococcus faecium, Pediococccus acidilactici and Lactobacillus plantarum against Listeria innocua as an indicator microorganism. Freeze-dried preparations of bacterial strains producing particular bacteriocins were tested by agar well-diffusion assay and by the traditional spread plate method. Plantaricin exhibited the highest anti-listerial effect among the tested bacteriocins. Pediocin also demonstrated a distinct inhibitory effect, but enterocin appeared to be heat labile and its efficiency was also suppressed under cold storage conditions. Plantaricin reduced Listeria innocua counts by 1 log in dairy spread made from cheese and quark. The formation of bacteriocins by various Lactobacillus plantarum strains were substantially influenced by the cultivation conditions of the mother culture and by the microbial preparation process before freeze-drying. Bacteriocins introduced into foodstuffs via protective cultures in situ offer new perspectives on enhancing food quality and safety.

  10. Alternative methodology for isolation of biosurfactant-producing bacteria.

    Science.gov (United States)

    Krepsky, N; Da Silva, F S; Fontana, L F; Crapez, M A C

    2007-02-01

    Wide biosurfactant application on biorremediation is limited by its high production cost. The search for cheaper biossurfactant production alternatives has guided our study. The use of selective media containing sucrose (10 g x L(-1)) and Arabian Light oil (2 g x L(-1)) as carbon sources showed to be effective to screen and maintain biosurfactant-producing consortia isolated from mangrove hydrocarbon-contaminated sediment. The biosurfactant production was assayed by kerosene, gasoline and Arabian Light Emulsification activity and the bacterial growth curve was determined by bacterial quantification. The parameters analyzed for biosurfactant production were the growth curve, salinity concentration, flask shape and oxygenation. All bacteria consortia screened were able to emulsify the petroleum derivatives tested. Biosurfactant production increased according to the incubation time; however the type of emulsification (non-aqueous phase or aqueous phase) did not change with time but with the compound tested. The methodology was able to isolate biosurfactant-producing consortia from superficial mangrove sediment contaminated by petroleum hydrocarbons and was recommended for selection of biosurfactant producing bacteria in tropical countries with low financial resources.

  11. BIOGAS PRODUCTION BY ENCAPSULATED METHANE-PRODUCING BACTERIA

    Directory of Open Access Journals (Sweden)

    Mohammad J. Taherzadeh

    2011-11-01

    Full Text Available Encapsulation of methane-producing bacteria was carried out with the objective of enhancing the rate of biogas production. Encapsulation with a one-step liquid-droplet-forming technique was employed for the natural membrane, resulting in spherical capsules with an average diameter and a membrane thickness of 4.3 and 0.2 mm, respectively. The capsules were made from alginate, using chitosan or Ca2+ as counter-ions, together with the addition of carboxymethylcellulose (CMC. A Durapore® membrane (hydrophilic PVDF with a pore size of 0.1 µm was used for synthetic encapsulating sachets having width and length dimensions 3×3 and 3×6 cm2 for holding the bacteria. During the digesting process, the dissolved substrates penetrated through the capsule membrane, and biogas inside the capsules was able to escape by diffusion. The results indicate encapsulation to be a promising method of digestion, with a high density of anaerobic bacteria. The method holds considerable potential for further development of membranes and their applications.

  12. Discovery and Mechanistic Characterization of Selective Inhibitors of H2S-producing Enzyme: 3-Mercaptopyruvate Sulfurtransferase (3MST) Targeting Active-site Cysteine Persulfide

    Science.gov (United States)

    Hanaoka, Kenjiro; Sasakura, Kiyoshi; Suwanai, Yusuke; Toma-Fukai, Sachiko; Shimamoto, Kazuhito; Takano, Yoko; Shibuya, Norihiro; Terai, Takuya; Komatsu, Toru; Ueno, Tasuku; Ogasawara, Yuki; Tsuchiya, Yukihiro; Watanabe, Yasuo; Kimura, Hideo; Wang, Chao; Uchiyama, Masanobu; Kojima, Hirotatsu; Okabe, Takayoshi; Urano, Yasuteru; Shimizu, Toshiyuki; Nagano, Tetsuo

    2017-01-01

    Very recent studies indicate that sulfur atoms with oxidation state 0 or −1, called sulfane sulfurs, are the actual mediators of some physiological processes previously considered to be regulated by hydrogen sulfide (H2S). 3-Mercaptopyruvate sulfurtransferase (3MST), one of three H2S-producing enzymes, was also recently shown to produce sulfane sulfur (H2Sn). Here, we report the discovery of several potent 3MST inhibitors by means of high-throughput screening (HTS) of a large chemical library (174,118 compounds) with our H2S-selective fluorescent probe, HSip-1. Most of the identified inhibitors had similar aromatic ring-carbonyl-S-pyrimidone structures. Among them, compound 3 showed very high selectivity for 3MST over other H2S/sulfane sulfur-producing enzymes and rhodanese. The X-ray crystal structures of 3MST complexes with two of the inhibitors revealed that their target is a persulfurated cysteine residue located in the active site of 3MST. Precise theoretical calculations indicated the presence of a strong long-range electrostatic interaction between the persulfur anion of the persulfurated cysteine residue and the positively charged carbonyl carbon of the pyrimidone moiety of the inhibitor. Our results also provide the experimental support for the idea that the 3MST-catalyzed reaction with 3-mercaptopyruvate proceeds via a ping-pong mechanism. PMID:28079151

  13. Carbapenemase producing bacteria in the food supply escaping detection.

    Directory of Open Access Journals (Sweden)

    Beverly J Morrison

    Full Text Available Carbapenem antimicrobials are critically important to human health and they are often the only remaining effective antibiotics for treating serious infections. Resistance to these drugs mediated by acquired carbapenemase enzymes is increasingly encountered in gram-negative bacteria and is considered a public health emergency. Animal origin food products are recognized as a potential source of resistant organisms, although carbapenem resistance has only recently been reported. In western countries there are active resistance surveillance programs targeting food animals and retail meat products. These programs primarily target beef, pork and poultry and focus exclusively on E. coli, Salmonella, Campylobacter spp. and Enterococcus spp. This global surveillance strategy does not capture the diversity of foods available nor does it address the presence of resistance gene-bearing mobile genetic elements in non-pathogenic bacterial taxa. To address this gap, a total of 121 seafood products originating in Asia purchased from retail groceries in Canada were tested. Samples were processed using a taxa-independent method for the selective isolation of carbapenem resistant organisms. Isolates were characterized by phenotypic antimicrobial susceptibility testing, PCR and DNA sequencing. Carbapenemase producing bacteria, all blaOXA-48, were isolated from 4 (3.3% of the samples tested. Positive samples originated from China (n=2 and Korea (n=2 and included squid, sea squirt, clams and seafood medley. Carbapenemase producing organisms found include Pseudomonas, Stenotrophomonas and Myroides species. These findings suggest that non-pathogenic bacteria, excluded from resistance surveillance programs, in niche market meats may serve as a reservoir of carbapenemase genes in the food supply.

  14. Isolation of Biosurfactant Producing Bacteria from Oil Reservoirs

    Directory of Open Access Journals (Sweden)

    A Tabatabaee, M Mazaheri Assadi, AA Noohi,VA Sajadian

    2005-01-01

    Full Text Available Biosurfactants or surface-active compounds are produced by microoaganisms. These molecules reduce surface tension both aqueous solutions and hydrocarbon mixtures. In this study, isolation and identification of biosurfactant producing bacteria were assessed. The potential application of these bacteria in petroleum industry was investigated. Samples (crude oil were collected from oil wells and 45 strains were isolated. To confirm the ability of isolates in biosurfactant production, haemolysis test, emulsification test and measurement of surface tension were conducted. We also evaluated the effect of different pH, salinity concentrations, and temperatures on biosurfactant production. Among importance features of the isolated strains, one of the strains (NO.4: Bacillus.sp showed high salt tolerance and their successful production of biosurfactant in a vast pH and temperature domain and reduced surface tension to value below 40 mN/m. This strain is potential candidate for microbial enhanced oil recovery. The strain4 biosurfactant component was mainly glycolipid in nature.

  15. The kinetic energy spectrum of protons produced by the dissociative ionization of H2 by electron impact

    Science.gov (United States)

    Khakoo, M. A.; Srivastava, S. K.

    1985-01-01

    The kinetic energy spectra of protons resulting from the dissociative ionization of H2 by electron impact have been measured for electron impact energies from threshold (approximately 17 eV) to 160 eV at 90 deg and 30 deg detection angles, using a crossed-beam experimental arrangement. To check reliability, two separate proton energy analysis methods have been employed, i.e., a time-of-flight proton energy analysis and an electrostatic hemispherical energy analyzer. The present results are compared with previous measurements.

  16. Steam reforming of biomass tar producing H2-rich gases over Ni/MgOx/CaO1-x catalyst.

    Science.gov (United States)

    Li, Chunshan; Hirabayashi, Daisuke; Suzuki, Kenzi

    2010-01-01

    Series nickel catalysts Ni/MgO(x)/CaO(1-)(x) (x=0.3, 0.5, 0.7, Ni: 5 wt%) were prepared and tested in fixed-bed reactor for biomass tar steam reforming, toluene as tar destruction model compound. Different ratios of MgO and CaO were mixed to simulate dolomite as Ni support. Two preparation methods: solid mixing with (SMW) and without water (SM) were used, the preparation methods and concentration of MgO had an important influence on toluene conversion and products. Catalysts prepared by SM method exhibited higher performance on toluene conversion, resulted in higher H(2) yield, and also, higher CO(2) and lower CO selectivity with higher temperature. For the same preparation method, higher concentration of MgO resulted in higher toluene conversion, and also influence on CO, CO(2) selectivity, but no obvious influence on the H(2) yield. Catalysts were characterized by BET, X-ray diffraction (XRD), SEM.

  17. Resistance to bacteriocins produced by Gram-positive bacteria.

    Science.gov (United States)

    Bastos, Maria do Carmo de Freire; Coelho, Marcus Lívio Varella; Santos, Olinda Cabral da Silva

    2015-04-01

    Bacteriocins are prokaryotic proteins or peptides with antimicrobial activity. Most of them exhibit a broad spectrum of activity, inhibiting micro-organisms belonging to different genera and species, including many bacterial pathogens which cause human, animal or plant infections. Therefore, these substances have potential biotechnological applications in either food preservation or prevention and control of bacterial infectious diseases. However, there is concern that continuous exposure of bacteria to bacteriocins may select cells resistant to them, as observed for conventional antimicrobials. Based on the models already investigated, bacteriocin resistance may be either innate or acquired and seems to be a complex phenomenon, arising at different frequencies (generally from 10(-9) to 10(-2)) and by different mechanisms, even amongst strains of the same bacterial species. In the present review, we discuss the prevalence, development and molecular mechanisms involved in resistance to bacteriocins produced by Gram-positive bacteria. These mechanisms generally involve changes in the bacterial cell envelope, which result in (i) reduction or loss of bacteriocin binding or insertion, (ii) bacteriocin sequestering, (iii) bacteriocin efflux pumping (export) and (iv) bacteriocin degradation, amongst others. Strategies that can be used to overcome this resistance are also addressed.

  18. Cytokinin producing bacteria stimulate amino acid deposition by wheat roots.

    Science.gov (United States)

    Kudoyarova, Guzel R; Melentiev, Alexander I; Martynenko, Elena V; Timergalina, Leila N; Arkhipova, Tatiana N; Shendel, Galina V; Kuz'mina, Ludmila Yu; Dodd, Ian C; Veselov, Stanislav Yu

    2014-10-01

    Phytohormone production is one mechanism by which rhizobacteria can stimulate plant growth, but it is not clear whether the bacteria gain from this mechanism. The hypothesis that microbial-derived cytokinin phytohormones stimulate root exudation of amino acids was tested. The rhizosphere of wheat plants was drenched with the synthetic cytokinin trans-zeatin or inoculated with Bacillus subtilis IB-22 (which produces zeatin type cytokinins) or B. subtilis IB-21 (which failed to accumulate cytokinins). Growing plants in a split root system allowed spatial separation of zeatin application or rhizobacterial inoculation to one compartment and analyses of amino acid release from roots (rhizodeposition) into the other compartment (without either microbial inoculation or treatment with exogenous hormone). Supplying B. subtilis IB-22 or zeatin to either the whole root system or half of the roots increased concentrations of amino acids in the soil solution although the magnitude of the increase was greater when whole roots were treated. There was some similarity in amino acid concentrations induced by either bacterial or zeatin treatment. Thus B. subtilis IB-22 increased amino acid rhizodeposition, likely due to its ability to produce cytokinins. Furthermore, B. subtilis strain IB-21, which failed to accumulate cytokinins in culture media, did not significantly affect amino acid concentrations in the wheat rhizosphere. The ability of rhizobacteria to produce cytokinins and thereby stimulate rhizodeposition may be important in enhancing rhizobacterial colonization of the rhizoplane.

  19. Bacteriocins produced by lactic acid bacteria: A review

    Directory of Open Access Journals (Sweden)

    Vesković-Moračanin Slavica M.

    2014-01-01

    Full Text Available Lactic acid bacteria (LAB have an essential role in the production of fermented products. With their metabolic activity, they influence the ripening processes - leading to desired sensory qualities while at the same time inhibiting the growth of undesired microorganisms. Because of their dominant role during fermentation and because of a long tradition of utilization, Lhave been designated as “safe microbiota”. Biological protection of LAB, as a naturally present and/or selected and intentionally added microflora, is realized through the production of non-specific (lactic acid, acetic acid and other volatile organic acids, hydrogen peroxide, diacetyl, etc and specific metabolites, bacteriocins. Bacteriocins are extracellularly released proteins or peptides which possess certain antibacterial activity towards certain types of microorganisms, usually related to the producing bacteria. Today, bacteriocins represent a very interesting potential for their application in the food industry. Their application can reduce the use of synthetic preservatives and/or the intensity of thermal treatment during food production consumer’s need for safe, fresh and minimally-processed food. With the intention of realizing this potential to the fullest, it is necessary to understand the nature of bacteriocins, their production mechanisms, regulations and actions, as well as the influence of external factors on the their antimicrobial activity. The composition of food, i.e. its characteristics (pH, temperature, ingredients and additives, types and quantities of epiphytic microbiota and the actual technological process used in production, can all influence the stability and activity of the added bacteriocins. The future research in this field should also aim to clarify this unknown aspect of the application of bacteriocins, to provide the necessary knowledge about the optimization of the external conditions and open up the possibility of discovering their new

  20. Cross-Contamination of Residual Emerging Contaminants and Antibiotic Resistant Bacteria in Lettuce Crops and Soil Irrigated with Wastewater Treated by Sunlight/H2O2.

    Science.gov (United States)

    Ferro, Giovanna; Polo-López, María I; Martínez-Piernas, Ana B; Fernández-Ibáñez, Pilar; Agüera, Ana; Rizzo, Luigi

    2015-09-15

    The sunlight/H2O2 process has recently been considered as a sustainable alternative option compared to other solar driven advanced oxidation processes (AOPs) in advanced treatment of municipal wastewater (WW) to be reused for crop irrigation. Accordingly, in this study sunlight/H2O2 was used as disinfection/oxidation treatment for urban WW treatment plant effluent in a compound parabolic collector photoreactor to assess subsequent cross-contamination of lettuce and soil by contaminants of emerging concern (CECs) (determined by QuEChERS extraction and LC-QqLIT-MS/MS analysis) and antibiotic resistant (AR) bacteria after irrigation with treated WW. Three CECs (carbamazepine (CBZ), flumequine (FLU), and thiabendazole (TBZ) at 100 μg L(-1)) and two AR bacterial strains (E. coli and E. faecalis, at 10(5) CFU mL(-1)) were spiked in real WW. A detection limit (DL) of 2 CFU mL(-1) was reached after 120 min of solar exposure for AR E. coli, while AR E. faecalis was more resistant to the disinfection process (240 min to reach DL). CBZ and TBZ were poorly removed after 90 min (12% and 50%, respectively) compared to FLU (94%). Lettuce was irrigated with treated WW for 5 weeks. CBZ and TBZ were accumulated in soil up to 472 ng g(-1) and 256 ng g(-1) and up-taken by lettuce up to 109 and 18 ng g(-1), respectively, when 90 min treated WW was used for irrigation; whereas no bacteria contamination was observed when the bacterial density in treated WW was below the DL. A proper treatment time (>90 min) should be guaranteed in order to avoid the transfer of pathogens from disinfected WW to irrigated crops and soil.

  1. H2O2 and/or TiO2 photocatalysis under UV irradiation for the removal of antibiotic resistant bacteria and their antibiotic resistance genes.

    Science.gov (United States)

    Guo, Changsheng; Wang, Kai; Hou, Song; Wan, Li; Lv, Jiapei; Zhang, Yuan; Qu, Xiaodong; Chen, Shuyi; Xu, Jian

    2017-02-05

    Inactivating antibiotic resistant bacteria (ARB) and removing antibiotic resistance genes (ARGs) are very important to prevent their spread into the environment. Previous efforts have been taken to eliminate ARB and ARGs from aqueous solution and sludges, however, few satisfying results have been obtained. This study investigated whether photocatalysis by TiO2 was able to reduce the two ARGs, mecA and ampC, within the host ARB, methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, respectively. The addition of H2O2 and matrix effect on the removal of ARB and ARGs were also studied. TiO2 thin films showed great effect on both ARB inactivation and ARGs removal. Approximately 4.5-5.0 and 5.5-5.8 log ARB reductions were achieved by TiO2 under 6 and 12mJ/cm(2) UV254 fluence dose, respectively. For ARGs, 5.8 log mecA reduction and 4.7 log ampC reduction were achieved under 120mJ/cm(2) UV254 fluence dose in the presence of TiO2. Increasing dosage of H2O2 enhanced the removal efficiencies of ARB and ARGs. The results also demonstrated that photocatalysis by TiO2 was capable of removing both intracellular and extracellular forms of ARGs. This study provided a potential alternative method for the removal of ARB and ARGs from aqueous solution.

  2. Effective concentration of the biocide injected for chemical control of biogenic H2S in producing formations

    Directory of Open Access Journals (Sweden)

    Jerzy Stopa

    2006-10-01

    Full Text Available When injecting chemicals to a wellbore, their concentration in the reservoir may significantly differ from their concentration in the fluid injected to the formation owing to such processes as dispersion, sorption, chemical reactions, biodegeneration.When designing the injection of biocides to remove hazardous bacteria, it is necessary to establish their effective concentration in the reservoir and variability in time. This concentration should maintain over some efficient value determined in laboratory condition, for a definite time. A mathematical model of the biocide mass transport in a near-wellbore zone is presented in the paper. The results of calculations of efficient concentrations for two field tests in gas wells are reported.

  3. Mechanistic modeling of biocorrosion caused by biofilms of sulfate reducing bacteria and acid producing bacteria.

    Science.gov (United States)

    Xu, Dake; Li, Yingchao; Gu, Tingyue

    2016-08-01

    Biocorrosion is also known as microbiologically influenced corrosion (MIC). Most anaerobic MIC cases can be classified into two major types. Type I MIC involves non-oxygen oxidants such as sulfate and nitrate that require biocatalysis for their reduction in the cytoplasm of microbes such as sulfate reducing bacteria (SRB) and nitrate reducing bacteria (NRB). This means that the extracellular electrons from the oxidation of metal such as iron must be transported across cell walls into the cytoplasm. Type II MIC involves oxidants such as protons that are secreted by microbes such as acid producing bacteria (APB). The biofilms in this case supply the locally high concentrations of oxidants that are corrosive without biocatalysis. This work describes a mechanistic model that is based on the biocatalytic cathodic sulfate reduction (BCSR) theory. The model utilizes charge transfer and mass transfer concepts to describe the SRB biocorrosion process. The model also includes a mechanism to describe APB attack based on the local acidic pH at a pit bottom. A pitting prediction software package has been created based on the mechanisms. It predicts long-term pitting rates and worst-case scenarios after calibration using SRB short-term pit depth data. Various parameters can be investigated through computer simulation.

  4. 气相分解硫化氢制氢的实验探索%The Experiment Discussion on the Decomposition of H2S in Gas Phase to Produce H2

    Institute of Scientific and Technical Information of China (English)

    付晓红

    2011-01-01

    采用波长为253.7nm的紫外光为光源,以Na2S溶液为反应液,进行了紫外光气相法分解硫化氢(H2S)制氢反应.考察了H2S通入流量、连续分解硫化氢、不同浓度的H2S、光催化分解H2S及气相分解与液相分解H2S的对比对产氢量的影响.研究结果表明,连续向反应液中通入H2S可以提高产氢量;气相直接分解H2S时,H2S分解的速度和其浓度成正比;气相分解H2S的反应在H2S浓度很高时比液相反应的效率高,在低浓度时,反应效率低于液相反应.

  5. A Ferredoxin- and F420H2-Dependent, Electron-Bifurcating, Heterodisulfide Reductase with Homologs in the Domains Bacteria and Archaea

    Science.gov (United States)

    Yan, Zhen

    2017-01-01

    ABSTRACT Heterodisulfide reductases (Hdr) of the HdrABC class are ancient enzymes and a component of the anaerobic core belonging to the prokaryotic common ancestor. The ancient origin is consistent with the widespread occurrence of genes encoding putative HdrABC homologs in metabolically diverse prokaryotes predicting diverse physiological functions; however, only one HdrABC has been characterized and that was from a narrow metabolic group of obligate CO2-reducing methanogenic anaerobes (methanogens) from the domain Archaea. Here we report the biochemical characterization of an HdrABC homolog (HdrA2B2C2) from the acetate-utilizing methanogen Methanosarcina acetivorans with unusual properties structurally and functionally distinct from the only other HdrABC characterized. Homologs of the HdrA2B2C2 archetype are present in phylogenetically and metabolically diverse species from the domains Bacteria and Archaea. The expression of the individual HdrA2, HdrB2, and HdrB2C2 enzymes in Escherichia coli, and reconstitution of an active HdrA2B2C2 complex, revealed an intersubunit electron transport pathway dependent on ferredoxin or coenzyme F420 (F420H2) as an electron donor. Remarkably, HdrA2B2C2 couples the previously unknown endergonic oxidation of F420H2 and reduction of ferredoxin with the exergonic oxidation of F420H2 and reduction of the heterodisulfide of coenzyme M and coenzyme B (CoMS-SCoB). The unique electron bifurcation predicts a role for HdrA2B2C2 in Fe(III)-dependent anaerobic methane oxidation (ANME) by M. acetivorans and uncultured species from ANME environments. HdrA2B2C2, ubiquitous in acetotrophic methanogens, was shown to participate in electron transfer during acetotrophic growth of M. acetivorans and proposed to be essential for growth in the environment when acetate is limiting. PMID:28174314

  6. 氯化铜脱除硫化氢气体制硫磺研究%H2S Removal with Cupric Chloride for Producing Sulfur

    Institute of Scientific and Technical Information of China (English)

    张俊丰; 童志权

    2006-01-01

    A novel technology of removing H2S with cupric chloride solution was developed in this paper. Cupric as the form of CuS deposition, the CuS produced was then oxidized by excessive cupric ion in another reactor meanwhile cupric ion that has been consumed can be recovered by the oxidization of CuCl2- with oxygen in air,and the solution can be circulated. Moreover, the leaching kinetics of CuS by cupric ion was studied. The removal efficiency of H2S is close to 100%, and the required operating condition is mild. Compared with other wet oxidization methods, no raw material is consumed except O2 in air, the process has no secondary pollution and no problem of degradation and scale, and the absorbent is much stable and reliable.

  7. H-2 incompatible chimera

    Energy Technology Data Exchange (ETDEWEB)

    Matzinger, P.; Mirkwood, G.

    1978-07-01

    Fully H-2 incompatible radiation chimeras were prepared using BALB congenic mice. Such chimeric mice were immunized in vivo against histocompatibility antigens of the C57BL/10Sn (B10) background in association with either the parental H-2 haplotypes, and their spleen cells subsequently boosted in vitro with the same minor antigens. Strong H-2-restricted cytotoxic activity against minor antigens was detected, and the specificity of the restriction could be to the H-2 haplotype of the donor or the host depending on the cells used for priming or boosting. Cross priming could also be demonstrated in these mice. The results show that fully allogenic radiation chimeras can produce H-2-restricted T-cell responses to minor histocompatibility (H) antigens, and are discussed in relation to contrasting results.

  8. Antimicrobial activity of bacteriocin-producing lactic acid bacteria isolated from cheeses and yogurts

    Science.gov (United States)

    2012-01-01

    The biopreservation of foods using bacteriocinogenic lactic acid bacteria (LAB) isolated directly from foods is an innovative approach. The objectives of this study were to isolate and identify bacteriocinogenic LAB from various cheeses and yogurts and evaluate their antimicrobial effects on selected spoilage and pathogenic microorganisms in vitro as well as on a food commodity. LAB were isolated using MRS and M17 media. The agar diffusion bioassay was used to screen for bacteriocin or bacteriocin-like substances (BLS) producing LAB using Lactobacillus sakei and Listeria innocua as indicator organisms. Out of 138 LAB isolates, 28 were found to inhibit these bacteria and were identified as strains of Enterococcus faecium, Streptococcus thermophilus, Lactobacillus casei and Lactobacillus sakei subsp. sakei using 16S rRNA gene sequencing. Eight isolates were tested for antimicrobial activity at 5°C and 20°C against L. innocua, Escherichia coli, Bacillus cereus, Pseudomonas fluorescens, Erwinia carotovora, and Leuconostoc mesenteroides subsp. mesenteroides using the agar diffusion bioassay, and also against Penicillium expansum, Botrytis cinerea and Monilinia frucitcola using the microdilution plate method. The effect of selected LAB strains on L. innocua inoculated onto fresh-cut onions was also investigated. Twenty percent of our isolates produced BLS inhibiting the growth of L. innocua and/or Lact. sakei. Organic acids and/or H2O2 produced by LAB and not the BLS had strong antimicrobial effects on all microorganisms tested with the exception of E. coli. Ent. faecium, Strep. thermophilus and Lact. casei effectively inhibited the growth of natural microflora and L. innocua inoculated onto fresh-cut onions. Bacteriocinogenic LAB present in cheeses and yogurts may have potential to be used as biopreservatives in foods. PMID:22963659

  9. Review on Nano SeleniumProduced by Bacteria

    Directory of Open Access Journals (Sweden)

    LI Ji-xiang

    2014-12-01

    Full Text Available Selenium (Se is a kind of essential trace element for people and animal, while ionic state of selenium is toxic with high concentrations and will cause the selenium pollution. Nano-selenium is stable, nontoxic with higher biological activity. Application of bacteria reducing selenite or selenate to biological nano-selenium has great potential in selenium pollution control and nano-selenium production. This review summarizes the research progress of the red elemental nano-selenium reduced by bacteria including characteristics and application of nano-selenium, effects of carbon and nitrogen source, oxygen, temperature and pH in bacteria nano-selenium production, and molecular mechanisms of nano-selenium reduced by bacteria.

  10. Characterization of In-Situ Cu–TiH2–C and Cu–Ti–C Nanocomposites Produced by Mechanical Milling and Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Hoang Oanh

    2017-03-01

    Full Text Available This study focuses on the fabrication and microstructural investigation of Cu–TiH2–C and Cu–Ti–C nanocomposites with different volume fractions (10% and 20% of TiC. Two mixtures of powders were ball milled for 10 h, consequently consolidated by spark plasma sintering (SPS at 900 and 1000 °C producing bulk materials with relative densities of 95–97%. The evolution process of TiC formation during sintering process was studied by using X-ray diffraction (XRD, scanning electron microscopy (SEM, and high resolution transmission electron microscopy (HRTEM. XRD patterns of composites present only Cu and TiC phases, no residual Ti phase can be detected. TEM images of composites with (10 vol % TiC sintered at 900 °C show TiC nanoparticles about 10–30 nm precipitated in copper matrix, most of Ti and C dissolved in the composite matrix. At the higher sintering temperature of 1000 °C, more TiC precipitates from Cu–TiH2–C than those of Cu–Ti–C composite, particle size ranges from 10 to 20 nm. The hardness of both nanocomposites also increased with increasing sintering temperature. The highest hardness values of Cu–TiH2–C and Cu–Ti–C nanocomposites sintered at 1000 °C are 314 and 306 HV, respectively.

  11. H2-Producing Bacterial Community during Rice Straw Decomposition in Paddy Field Soil: Estimation by an Analysis of [FeFe]-Hydrogenase Gene Transcripts.

    Science.gov (United States)

    Baba, Ryuko; Asakawa, Susumu; Watanabe, Takeshi

    2016-09-29

    The transcription patterns of [FeFe]-hydrogenase genes (hydA), which encode the enzymes responsible for H2 production, were investigated during rice straw decomposition in paddy soil using molecular biological techniques. Paddy soil amended with and without rice straw was incubated under anoxic conditions. RNA was extracted from the soil, and three clone libraries of hydA were constructed using RNAs obtained from samples in the initial phase of rice straw decomposition (day 1 with rice straw), methanogenic phase of rice straw decomposition (day 14 with rice straw), and under a non-amended condition (day 14 without rice straw). hydA genes related to Proteobacteria, Firmicutes, Bacteroidetes, Chloroflexi, and Thermotogae were mainly transcribed in paddy soil samples; however, their proportions markedly differed among the libraries. Deltaproteobacteria-related hydA genes were predominantly transcribed on day 1 with rice straw, while various types of hydA genes related to several phyla were transcribed on day 14 with rice straw. Although the diversity of transcribed hydA was significantly higher in the library on day 14 with rice straw than the other two libraries, the composition of hydA transcripts in the library was similar to that in the library on day 14 without rice straw. These results indicate that the composition of active H2 producers and/or H2 metabolic patterns dynamically change during rice straw decomposition in paddy soil.

  12. Marine bacteria producing antibacterial compounds isolated from inter-tidal invertebrates

    OpenAIRE

    León, Jorge; Laboratorio de Microbiología Ambiental y Biotecnología, Facultad de Ciencias Biológicas, Universidad Nacional Mayor de San Marcos, Apartado 110058, Lima Perú.; Liza, Libia; Laboratorio de Microbiología Ambiental y Biotecnología, facultad de Ciencias Biológicas,Universidad Nacional Mayor de San Marcos, Lima, Perú. Biólogo. Microbiólogo.; Soto, Isela; Laboratorio de Microbiología Ambiental y Biotecnología, Facultad de Ciencias Biológicas, Universidad Nacional Mayor de San Marcos, Apartado 110058, Lima Perú.; Torres, Magali; Laboratorio de Microbiología Ambiental y Biotecnología, facultad de Ciencias Biológicas,Universidad Nacional Mayor de San Marcos, Lima, Perú. Biólogo. Microbiólogo; Orosco, Andrés; Laboratorio de Microbiología Ambiental y Biotecnología, facultad de Ciencias Biológicas,Universidad Nacional Mayor de San Marcos, Lima, Perú. Biólogo. Microbiólogo

    2010-01-01

    Prospective sampling activities of intertidal invertebrates in the Ancon Bay (Lima, Peru) were done in order to select marine bacteria producing antimicrobial substances. The study included the isolation of bacteria in marine agar, in vitro antimicrobial susceptibility testing and electronic microscopic observations. We report the isolation, phenotypical characterization and antimicrobial properties of 10 strains of marine bacteria including the genus Vibrio, Pseudomonas, and Flavobacteri...

  13. Selection, phenotyping and identification of acid and hydrogen peroxide producing bacteria from vaginal samples of Canadian and East African women.

    Directory of Open Access Journals (Sweden)

    John J Schellenberg

    Full Text Available The common but poorly understood condition known as bacterial vaginosis (BV increases vulnerability to HIV infection and is associated with the absence of H(2O(2-producing Lactobacillus. Vaginal lactic acid bacteria (LAB produce anti-HIV factors such as organic acids and hydrogen peroxide (H(2O(2, and may bind and inactivate HIV particles during scavenging of mannose. These factors define potential criteria for initial selection of candidate probiotics to block heterosexual transmission of HIV. Therefore, the primary goal of this study was to characterize acid production on mannose and H(2O(2 production in vaginal isolates from Canadian adolescents (192 isolates, 16 individuals and commercial sex workers in Nairobi, Kenya (576 isolates, 96 individuals. Selection of isolates from H(2O(2-detecting media suggested an idiosyncratic individual-level profile and extensive phenotypic diversity, including the identification of a subset of "double-strong" acid- and H(2O(2-producers with phenotypes similar to well-characterized probiotic strains. Molecular fingerprinting of all isolates by capillary electrophoresis of 16S-23S rRNA interspacer amplicons was coupled with chaperonin-60 universal target (cpn60 UT sequencing in a subset, tentatively identifying 96% of isolates although only 19% were sequenced. Most isolates belonged to Lactobacillus, Streptococcus, Bifidobacterium or Gardnerella, with a total of 37 species in 15 genera, as well as 5 potentially novel organisms, identified in this study. This sensitivity was likely enhanced by phenotype-based selection on two chromogenic media formulations. Identification of double-strong isolates may provide a rational basis for selection and further characterization of vaginal probiotics, with potential application as part of HIV prevention initiatives in western Canada and East Africa.

  14. The role of resistance to bile salts and acid tolerance of exopolysaccharides (EPSS produced by yogurt starter bacteria

    Directory of Open Access Journals (Sweden)

    Boke Hatice

    2010-01-01

    Full Text Available The aim of this study was to investigate a possible relation between EPS production and resistance to bile salts and tolerance to low pH. Eight strains which produced the highest and lowest amount of EPS (16- 211mg/l were selected among 54 bacteria isolated from yogurt. Additionally, they were tested for resistance to bile salts (0.15, 0.3 % and tolerance to low pH (2.0-3.0. After treatment with bile salts and acid, viable bacteria (log cfu ml-1 were determined by surface plating. The high EPS producing strains (B3, G12, W22 showed a significant (P<0.05 protective effect against low pH (pH 2.0. All Streptococcus thermophilus strains showed a higher tolerance to bile salts than the Lactobacillus delbrueckii subsp. bulgaricus strains. The high EPS-producing S. thermophilus (W22, T12 and L. bulgaricus (B3, G2 strains showed a significant (P<0.01 protective effect against bile salts (0.3 %.

  15. Prevalence of β-lactamase-producing bacteria in human periodontitis

    NARCIS (Netherlands)

    Rams, T E; Degener, J E; van Winkelhoff, A J

    2013-01-01

    BACKGROUND AND OBJECTIVE: Beta-lactam antibiotics prescribed in periodontal therapy are vulnerable to degradation by bacterial β-lactamases. This study evaluated the occurrence of β-lactamase-positive subgingival bacteria in chronic periodontitis subjects of USA origin, and assessed their in vitro r

  16. Distribution of Biosurfactant-Producing Bacteria in Undisturbed and Contaminated Arid Southwestern Soils

    OpenAIRE

    Bodour, Adria A.; Drees, Kevin P.; Maier, Raina M.

    2003-01-01

    Biosurfactants are a unique class of compounds that have been shown to have a variety of potential applications in the remediation of organic- and metal-contaminated sites, in the enhanced transport of bacteria, in enhanced oil recovery, as cosmetic additives, and in biological control. However, little is known about the distribution of biosurfactant-producing bacteria in the environment. The goal of this study was to determine how common culturable surfactant-producing bacteria are in undist...

  17. STUDY ON SURGICAL SITE INFECTIONS CAUSED BY ESBL PRODUCING GRAM NEGATIVE BACTERIA

    Directory of Open Access Journals (Sweden)

    Rambabu

    2015-09-01

    Full Text Available Surgical site infections have been a major problem, because of the emergence of drug resistant bacteria, in particular B - lactamase producing bacteria. Extended spectrum beta lactamase producing gram negative organisms pose a great challenge in treatment o f SSI present study is aimed at determining multiple drug resistance in gram negative bacteria & to find out ESBL producers, in correlation with treatment outcome. A total of 120 wound infected cases were studied. Staphylococcus aureus was predominant bact erium - 20.Among gram negative bacteria, Pseudomonas species is predominant (14 followed by Escherichia coli (13 , Klebsiella species (12 , Proteus (9 Citrobacter (4 Providencia (2 & Acinetobacter species (2 . Out of 56 gramnegative bacteria isolated, 20 were i dentified as ESBL producers, which was statistically significant. Delay in wound healing correlated with infection by ESBL producers, which alarms the need of abstinence from antibiotic abuse

  18. Hexagonal plate-like magnetite nanocrystals produced in komatiite-H2O-CO2 reaction system at 450°C

    Science.gov (United States)

    Hao, Xi-Luo; Li, Yi-Liang

    2015-10-01

    Batch experiments of komatiite-H2O-CO2 system with temperatures from 200 to 450°C were performed to simulate the interactions between the newly formed ultramafic crust and the proto-atmosphere on Earth before the formation of its earliest ocean. Particularly, magnetite nanocrystals were observed in the experiment carried out at 450°C that are characterized by their hexagonal platelet-like morphology and porous structure. Exactly the same set of lattice fringes on the two opposite sides of one pore suggests post-crystallization erosion. The results demonstrate that magnetite could be produced by the direct interactions between the ultramafic rocky crust and the atmosphere before the formation of the ocean on the Hadean Earth. These magnetite nanoparticles could serve as a catalyst in the synthesis of simple organic molecules during the organochemical evolution towards life.

  19. Inhibitory effect of bacteriocin-producing lactic acid bacteria against histamine-forming bacteria isolated from Myeolchi-jeot

    Directory of Open Access Journals (Sweden)

    Eun-Seo Lim

    2016-12-01

    Full Text Available Abstract The objectives of this study were to identify the histamine-forming bacteria and bacteriocin- producing lactic acid bacteria (LAB isolated from Myeolchi-jeot according to sequence analysis of the 16S rRNA gene, to evaluate the inhibitory effects of the bacteriocin on the growth and histamine accumulation of histamine-forming bacteria, and to assess the physico-chemical properties of the bacteriocin. Based on 16S rRNA gene sequences, histamine-forming bacteria were identified as Bacillus licheniformis MCH01, Serratia marcescens MCH02, Staphylococcus xylosus MCH03, Aeromonas hydrophila MCH04, and Morganella morganii MCH05. The five LAB strains identified as Pediococcus acidilactici MCL11, Leuconostoc mesenteroides MCL12, Enterococcus faecium MCL13, Lactobacillus sakei MCL14, and Lactobacillus acidophilus MCL15 were found to produce an antibacterial compound with inhibitory activity against the tested histamine-producing bacteria. The inhibitory activity of these bacteriocins obtained from the five LAB remained stable after incubation at pH 4.0–8.0 and heating for 10 min at 80 °C; however, the bacteriocin activity was destroyed after treatment with papain, pepsin, proteinase K, α-chymotrypsin, or trypsin. Meanwhile, these bacteriocins produced by the tested LAB strains also exhibited histamine-degradation ability. Therefore, these antimicrobial substances may play a role in inhibiting histamine formation in the fermented fish products and preventing seafood-related food-borne disease caused by bacterially generated histamine.

  20. Lack of Effect of H2-Receptor Antagonists and Antacids on the Gastric and Duodenal Gastrin-, Somatostatin- and Serotonin-Producing Cells in Patients with Acid Peptic Disorders

    Directory of Open Access Journals (Sweden)

    WR Yacoub

    1996-01-01

    Full Text Available Standard therapeutic approaches to acid peptic disorders have dealt with neutralizing or inhibiting aggressive factors and/or bolstering defensive factors. Gastric and duodenal mucosal biopsies were examined from 90 patients with various acid peptic disorders, as follows: reflux esophagitis (n=24, gastric ulcer (n=13, duodenal ulcer (n=47 and nonulcer dyspepsia (n=6. Seven patients with minimal dyspeptic symptoms and an endoscopically and histologically normal stomach and duodenum served as controls. Immunoperoxidase staining for gastrin-producing G cells, somatostatin-producing D cells and serotonin-producing EC cells was carried out on fundic, antral and duodenal biopsies, and quantitated using a Zeiss MOP videoplan. No significant effects secondary to treatment with antacid, ranitidine or cimetidine were observed on endocrine cell densities and ratios. Biopsies obtained on different occasions over time indicated that in patients on enprostil (a synthetic E2 prostaglandin, there was a trend towards increasing cell counts, suggesting that the serum gastrin-lowering effect of this drug may result from inhibition of gastrin release. Thus, H2-receptor antagonists and antacids do not alter gastric or duodenal mucosal G, D or EC cells in patients with acid peptic disorders.

  1. Bacteriocinogenic Bacteria Isolated from Raw Goat Milk and Goat Cheese Produced in the Center of México.

    Science.gov (United States)

    Hernández-Saldaña, Oscar F; Valencia-Posadas, Mauricio; de la Fuente-Salcido, Norma M; Bideshi, Dennis K; Barboza-Corona, José E

    2016-09-01

    Currently, there are few reports on the isolation of microorganisms from goat milk and goat cheese that have antibacterial activity. In particular, there are no reports on the isolation of microorganisms with antibacterial activity from these products in central Mexico. Our objective was to isolate bacteria, from goat products, that synthesized antimicrobial peptides with activity against a variety of clinically significant bacteria. We isolated and identified Lactobacillus rhamnosus, L. plantarum, L. pentosus, L. helveticus and Enterococcus faecium from goat cheese, and Aquabacterium fontiphilum, Methylibium petroleiphilum, Piscinobacter aquaticus and Staphylococcus xylosus from goat milk. These bacteria isolated from goat cheese were able to inhibit Staphylococcus aureus, Bacillus cereus, Escherichia coli, Listeria monocytogenes, L. inoccua, Pseudomona aeruginosa, Shigella flexneri, Serratia marcescens, Enterobacter cloacae and Klebsiella pneumoniae. In addition, bacteria from goat milk showed inhibitory activity against B. cereus, L. lactis, E. coli, S. flexneri, E. cloacae and K. pneumonia; S. aureus, L. innocua, S. agalactiae and S. marcescens. The bacteriocins produced by these isolates were shown to be acid stable (pH 2-6) and thermotolerant (up to 100 °C), but were susceptible to proteinases. When screened by PCR for the presence of nisin, pediocin and enterocin A genes, none was found in isolates recovered from goat milk, and only the enterocin A gene was found in isolates from goat cheese.

  2. Differential attraction of malaria mosquitoes to volatile blends produced by human skin bacteria

    NARCIS (Netherlands)

    Verhulst, N.O.; Andriessen, R.; Groenhagen, U.; Bukovinszkine-Kiss, G.; Schulz, S.; Takken, W.; Loon, van J.J.A.; Schraa, G.; Smallegange, R.C.

    2010-01-01

    The malaria mosquito Anopheles gambiae sensu stricto is mainly guided by human odour components to find its blood host. Skin bacteria play an important role in the production of human body odour and when grown in vitro, skin bacteria produce volatiles that are attractive to A. gambiae. The role of

  3. Phylogenetic diversity of cultivalble butyrate-producing bacteria from pig gut content and feces

    DEFF Research Database (Denmark)

    Li, Xiaoqiong; Højberg, Ole; Canibe, Nuria

    2016-01-01

    Butyrate is a preferred energy source for colonocytes and is considered crucial for maintaining colonic health in humans and animals. To investigate the diversity of cultivable butyrate-producing bacteria in pig gut, bacteria were isolated from intestinal digesta (Exp. 1) and feces (Exp. 2...

  4. Preparation and characterization of the lightweight concrete produced by H2 O2 chemical foaming in situ%H2 O2原位发泡轻混凝土的制备与性能表征∗

    Institute of Scientific and Technical Information of China (English)

    樊传刚; 吴瑞; 黄兴田; 陈贺; 孟方方; 李家茂

    2016-01-01

    The lightweight concrete (LC)specimens were prepared using the method of chemical foaming in situ. In the foaming process,the H2 O2 was used as foaming agent,the coarser and fine expanded perlites were used as lightweight aggregate and as carrier for H2 O2 respectively,and the gelatin was used as foam stabilizer.The foaming reaction of H2 O2 was taken place after it was being charged into carriers and the charged carriers were mixed into the mortar previously.The mortar was enclosed by the lightweight aggregates in fresh concrete.The properties of the resulting LC specimens were characterized systemically.It was found that the adding amount of 1.5wt% foam stabilizer had the promising stabilization for the foam formed in situ,which resulted in the bubbles with 0.5-1 mm diameter in homogeneous distribution.The bulk densities (BD)of resulting LC speci-mens were decreased with the increasing of the adding amount of foaming agent,and increased with the adding amount of foam stabilizer.For the resulting LC specimens with foam stabilizer amount of 1.5wt%,their 28 d compressive strengths (CS)and thermal conducting coefficients (TCC)were decreased with the increase of the amount of foaming agent.Among them,the resulting LC specimen with foaming agent of 1.4wt% had the 28 d CS of 21 MPa and the BD of 940 kg/m3 .As compared with that of the resulting LC specimen without foaming agent,its specific strength value was improved by 14% and its TCC was decreased by 13%,respectively.%以 H2 O2溶液(质量浓度30%)为发泡剂,粗、细膨胀珍珠岩颗粒为轻集料和发泡剂载体,明胶为稳泡剂,采用将加载发泡剂的载体拌入轻集料混凝土的水泥浆中原位化学发泡的方法,制备出了系列轻混凝土试样,并对其性能进行了系统表征.结果表明,原位发泡轻混凝土中外加1.5%(质量分数)胶凝材料量的稳泡剂后,对气泡有较为理想的稳泡作用,可获得均匀分布的细小气泡(气泡直径0.5~1 mm).原位

  5. BIODEGRADATION OF PETROLEUM-WASTE BY BIOSURFACTANT-PRODUCING BACTERIA

    Energy Technology Data Exchange (ETDEWEB)

    Brigmon, R; Grazyna A. Plaza, G; Kamlesh Jangid, K; Krystyna Lukasik, K; Grzegorz Nalecz-Jawecki, G; Topher Berry, T

    2007-05-16

    The degradation of petroleum waste by mixed bacterial cultures which produce biosurfactants: Ralstonia pickettii SRS (BP-20), Alcaligenes piechaudii SRS (CZOR L-1B), Bacillus subtilis (1'- 1a), Bacillus sp. (T-1) and Bacillus sp. (T'-1) was investigated. The total petroleum hydrocarbons were degraded substantially (91 %) by the mixed bacterial culture in 30 days (reaching up to 29 % in the first 72 h). Similarly, the toxicity of the biodegraded petroleum waste decreased 3 times after 30 days as compared to raw petroleum waste. Thus, the mixed bacterial strains effectively clean-up the petroleum waste and they can be used in other bioremediation processes.

  6. Development of molecular approach based on PCR assay for detection of histamine producing bacteria.

    Science.gov (United States)

    Wongsariya, Karn; Bunyapraphatsara, Nuntavan; Yasawong, Montri; Chomnawang, Mullika Traidej

    2016-01-01

    Histamine fish poisoning becomes highly concern not only in public health but also economic aspect. Histamine is produced from histidine in fish muscles by bacterial decarboxylase enzyme. Several techniques have been developed to determine the level of histamine in fish and their products but the effective method for detecting histamine producing bacteria is still required. This study was attempted to detect histamine producing bacteria by newly developed PCR condition. Histamine producing bacteria were isolated from scombroid fish and determined the ability to produce histamine of isolated bacteria by biochemical and TLC assays. PCR method was developed to target the histidine decarboxylase gene (hdc). The result showed that fifteen histamine producing bacterial isolates and three standard strains produced an amplicon at the expected size of 571 bp after amplified by PCR using Hdc_2F/2R primers. Fifteen isolates of histamine producing bacteria were classified as M. morganii, E. aerogenes, and A. baumannii. The lowest detection levels of M. morganii and E. aerogenes were 10(2) and 10(5) Cfu/mL in culture media and 10(3) and 10(6) Cfu/mL in fish homogenates, respectively. The limit of detection by this method was clearly shown to be sensitive because the primers could detect the presence of M. morganii and E. aerogenes before the histamine level reached the regulation level at 50 ppm. Therefore, this PCR method exhibited the potential efficiency for detecting the hdc gene from histamine producing bacteria and could be used to prevent the proliferation of histamine producing bacteria in fish and fish products.

  7. Distribution of Sulfate-Reducing Bacteria, O2, and H2s in Photosynthetic Biofilms Determined by Oligonucleotide Probes and Microelectrodes Rid A-1977-2009

    DEFF Research Database (Denmark)

    RAMSING, NB; KUHL, M.; JØRGENSEN, BB

    1993-01-01

    penetration, we incubated two 4-mm-thick biofilm samples in darkness or exposed to light at natural intensity. Gradients of O2, H2S, and pH were examined with microelectrodes during incubation. The samples were subsequently frozen with liquid nitrogen and sliced on a cryomicrotome in 20-mum vertical slices...

  8. Phytase-Producing Bacteria from Extreme Regions in Indonesia

    Directory of Open Access Journals (Sweden)

    Sajidan

    2015-10-01

    Full Text Available ABSTRACTIn this study, 154 isolates capable of producing extracellular phytate-degrading activity were isolated from four soil samples from volcanic areas in Central Java, Indonesia. Six strains with high phytate-degrading activity were selected for strain identification and characterization of the corresponding phytate-degrading enzyme. Blast analysis of 16S rRNA gene sequences revealed high similarities for all the six isolates to reference sequences belonging to the genusBacillus. Isolates MS5, MC6, D10 and D16 showed 99% sequence identity toB. cereus, while isolate MC8 exhibited 99% sequence identity toB. aryabhatti and D6 99% sequence identity toB. psychrotolerans. The crude extracellular phytase preparations from the isolates showed following optimal conditions for phytate dephosphorylation: pH 4.0 and 50°C (isolate D10, pH 5.0 and 60°C (isolate MC6, and isolate MS5, pH 6.0 and 50°C (isolate D16 and pH 6.0 and 60°C (isolate D6 and pH 6.0 and 40°C (isolate MC8. Zn2+ and Fe3+ strongly inhibited phytate dephosphorylation with all phytase preparations studied. In the presence of Ca2+, an increase in phytase activity of 10-15% was obtained.

  9. [Antibacterial activity of essential oil vapor for histamine-producing bacteria].

    Science.gov (United States)

    Kamii, Eri; Terada, Gaku; Akiyama, Junki; Isshiki, Kenji

    2011-01-01

    In this study, we evaluated the antibacterial activity of essential oil vapors against histamine-producing bacteria Morganella morganii NBRC3848 and Raultella planticola NBRC3317. We measured the minimum inhibitory dose (MID) of 14 essential oils towards these two strains. Allyl isothiocyanate (AIT) and salicylaldehyde (SA) vapors showed higher antibacterial activity than the other 12 essential oil vapors. Both AIT and SA vapors suppressed growth of total aerobic bacteria and histamine-producing bacteria in bigeye tuna and mackerel meat during storage at 12°C. These vapors also inhibited histamine accumulation in bigeye tuna meat and mackerel meat. Thus, application of AIT and SA vapors is effective for preventing increase of histamine-producing bacteria and histamine formation in fish meat.

  10. Antimicrobial chemicals in hoopoe preen secretions are produced by symbiotic bacteria.

    Science.gov (United States)

    Martín-Vivaldi, Manuel; Peña, Aránzazu; Peralta-Sánchez, Juan Manuel; Sánchez, Lourdes; Ananou, Samir; Ruiz-Rodríguez, Magdalena; Soler, Juan José

    2010-01-07

    Animals frequently use metabolites produced by symbiotic bacteria as agents against pathogens and parasites. Secretions from the preen gland of birds are used for this purpose, although its chemicals apparently are produced by the birds themselves. European hoopoes Upupa epops and green woodhoopoes Phoeniculus purpureus harbour symbiotic bacteria in the uropygial gland that might be partly responsible for the chemical composition of secretions. Here we investigate the antimicrobial activity of the volatile fraction of chemicals in hoopoe preen secretions, and, by means of experimental antibiotic injections, test whether symbiotic bacteria living within the uropygial gland are responsible for their production. Hoopoes produce two different kinds of secretions that differ drastically in their chemical composition. While the malodorous dark secretions produced by nestlings included a complex mix of volatiles, these chemicals did not appear in white secretions produced by non-nesting birds. All volatiles detected showed strong antibacterial activity, and a mixture of the chemicals at the concentrations measured in nestling glands inhibited the growth of all bacterial strains assayed. We found support for the hypothesized role of bacteria in the production of such antimicrobial chemicals because experimental clearance of bacteria from glands of nestlings with antibiotics resulted in secretions without most of the volatiles detected in control individuals. Thus, the presence of symbiotic bacteria in the uropygial gland provides hoopoes with potent antimicrobials for topical use.

  11. Tetrodotoxin-Producing Bacteria: Detection, Distribution and Migration of the Toxin in Aquatic Systems

    Directory of Open Access Journals (Sweden)

    Timur Yu. Magarlamov

    2017-05-01

    Full Text Available This review is devoted to the marine bacterial producers of tetrodotoxin (TTX, a potent non-protein neuroparalytic toxin. In addition to the issues of the ecology and distribution of TTX-producing bacteria, this review examines issues relating to toxin migration from bacteria to TTX-bearing animals. It is shown that the mechanism of TTX extraction from toxin-producing bacteria to the environment occur through cell death, passive/active toxin excretion, or spore germination of spore-forming bacteria. Data on TTX microdistribution in toxic organs of TTX-bearing animals indicate toxin migration from the digestive system to target organs through the transport system of the organism. The role of symbiotic microflora in animal toxicity is also discussed: despite low toxin production by bacterial strains in laboratory conditions, even minimal amounts of TTX produced by intestinal microflora of an animal can contribute to its toxicity. Special attention is paid to methods of TTX detection applicable to bacteria. Due to the complexity of toxin detection in TTX-producing bacteria, it is necessary to use several methods based on different methodological approaches. Issues crucial for further progress in detecting natural sources of TTX investigation are also considered.

  12. The spread of carbapenemase-producing bacteria in Africa: a systematic review.

    Science.gov (United States)

    Manenzhe, Rendani I; Zar, Heather J; Nicol, Mark P; Kaba, Mamadou

    2015-01-01

    Carbapenems are the last line of defence against ever more prevalent MDR Gram-negative bacteria, but their efficacy is threatened worldwide by bacteria that produce carbapenemase enzymes. The epidemiology of bacteria producing carbapenemases has been described in considerable detail in Europe, North America and Asia; however, little is known about their spread and clinical relevance in Africa. We systematically searched in PubMed, EBSCOhost, Web of Science, Scopus, Elsevier Masson Consulte and African Journals Online, international conference proceedings, published theses and dissertations for studies reporting on carbapenemase-producing bacteria in Africa. We included articles published in English or French up to 28 February 2014. We calculated the prevalence of carbapenemase producers only including studies where the total number of isolates tested was at least 30. Eighty-three studies were included and analysed. Most studies were conducted in North Africa (74%, 61/83), followed by Southern Africa (12%, 10/83), especially South Africa (90%, 9/10), West Africa (8%, 7/83) and East Africa (6%, 6/83). Carbapenemase-producing bacteria were isolated from humans, the hospital environment and community environmental water samples, but not from animals. The prevalence of carbapenemase-producing isolates in hospital settings ranged from 2.3% to 67.7% in North Africa and from 9% to 60% in sub-Saharan Africa. Carbapenemase-producing bacteria have been described in many African countries; however, their prevalence is poorly defined and has not been systematically studied. Antibiotic stewardship and surveillance systems, including molecular detection and genotyping of resistant isolates, should be implemented to monitor and reduce the spread of carbapenemase-producing bacteria. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  13. H_2O_2对水稻白叶枯病菌过氧化氢酶相关基因crg表达的诱导作用%Induction of bacterial catalase-related gene expression by H_2O_2 produced during interaction of rice suspension-cultured cells with Xanthomonas oryzae pv. oryzae or applied exogenously

    Institute of Scientific and Technical Information of China (English)

    周建波; 吴茂森; 胡俊; 何晨阳

    2009-01-01

    为了阐明H_2O_2对水稻白叶枯病菌(Xanthomonas oryzae pv.oryzae,Xoo)过氧化氢酶(CAT)相关基因(crg)表达的诱导作用,本研究定量分析了在水稻细胞-Xoo互作体系及其加入H_2O_2清除剂CAT后H_2O_2产量和crg表达;外源添加H_2O_2后的病菌生长和crg表达.结果表明:在互作条件下,H_2O_2含量稳定增加,10 h可达到峰值;在互作6 h时crg显著地被诱导表达;加入 CAT显著地降低了H_2O_2含量和crg表达;在外源H_2O_2胁迫条件下,H_2O_2以浓度效应的方式影响病菌增殖,显著地诱导了catB和srpA表达.因此,Xoo-水稻互作导致了H_2O_2的发生.无论是互作产生的还是外源的H_2O_2均显著地诱导了Xoo crg表达,从而活化了H_2O_2降解途径.%To elucidate the role of hydrogen peroxide (H_2O_2) produced during the interaction of rice suspension-cultured cells with Xanthomonas oryzae pv. oryzae (Xoo) or applied exogenously in inducing expression of bacterial catalase-related gene (crg), H_2O_2 production and crg expression during the rice-Xoo interaction, in which catalase (CAT) was exogenously added or not, were quantitatively analyzed. In vitro growth and crg expression of Xoo exposed to exogenously-applied H_2O_2 were quantitatively examined as well. Significant increase in H_2O_2 content and crg expression was observed during the interaction, while reduction in H_2O_2 concentration and crg expression was obviously found when CAT was exogenously added to the rice-Xoo interacting system. Growth in vitro was inhibited by exogenously-applied H_2O_2 in a dosage manner, which strongly induced the expression of catB and srpA. Therefore, H_2O_2 production was resulted from the rice-Xoo interaction, and crg expression was significantly induced by H_2O_2 either produced during the interaction or added exogenously.

  14. A direct pre-screen for marine bacteria producing compounds inhibiting quorum sensing reveals diverse planktonic bacteria that are bioactive.

    Science.gov (United States)

    Linthorne, Jamie S; Chang, Barbara J; Flematti, Gavin R; Ghisalberti, Emilio L; Sutton, David C

    2015-02-01

    A promising new strategy in antibacterial research is inhibition of the bacterial communication system termed quorum sensing. In this study, a novel and rapid pre-screening method was developed to detect the production of chemical inhibitors of this system (quorum-quenching compounds) by bacteria isolated from marine and estuarine waters. This method involves direct screening of mixed populations on an agar plate, facilitating specific isolation of bioactive colonies. The assay showed that between 4 and 46 % of culturable bacteria from various samples were bioactive, and of the 95 selectively isolated bacteria, 93.7 % inhibited Vibrio harveyi bioluminescence without inhibiting growth, indicating potential production of quorum-quenching compounds. Of the active isolates, 21 % showed further activity against quorum-sensing-regulated pigment production by Serratia marcescens. The majority of bioactive isolates were identified by 16S ribosomal DNA (rDNA) amplification and sequencing as belonging to the genera Vibrio and Pseudoalteromonas. Extracts of two strongly bioactive Pseudoalteromonas isolates (K1 and B2) were quantitatively assessed for inhibition of growth and quorum-sensing-regulated processes in V. harveyi, S. marcescens and Chromobacterium violaceum. Extracts of the isolates reduced V. harveyi bioluminescence by as much as 98 % and C. violaceum pigment production by 36 % at concentrations which had no adverse effect on growth. The activity found in the extracts indicated that the isolates may produce quorum-quenching compounds. This study further supports the suggestion that quorum quenching may be a common attribute among culturable planktonic marine and estuarine bacteria.

  15. ISOLATION AND IDENTIFICATION OF LACTIC ACID PRODUCING BACTERIA FROM CAMEL MILK

    OpenAIRE

    Toqeer Ahmad, Rashida Kanwal, Izhar Hussain Athar1, Najam Ayub

    2002-01-01

    Lactic acid bacteria (LAB) were isolated from camel milk by culturing the camel milk on specific media and pure culture was obtained by sub culturing. Purification of culture was confirmed by Gram's staining and identified by different bio-chemical tests. Camel milk contains lactic acid producing bacteria including Strpptococci such as S. cremoris and S. lactis and Lactobacilli such as L. acidophilus L. acidophilus grows more rapidly in camel milk than others as its growth is supported by cam...

  16. H2@Scale Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ruth, Mark

    2017-07-12

    'H2@Scale' is a concept based on the opportunity for hydrogen to act as an intermediate between energy sources and uses. Hydrogen has the potential to be used like the primary intermediate in use today, electricity, because it too is fungible. This presentation summarizes the H2@Scale analysis efforts performed during the first third of 2017. Results of technical potential uses and supply options are summarized and show that the technical potential demand for hydrogen is 60 million metric tons per year and that the U.S. has sufficient domestic resources to meet that demand. A high level infrastructure analysis is also presented that shows an 85% increase in energy on the grid if all hydrogen is produced from grid electricity. However, a preliminary spatial assessment shows that supply is sufficient in most counties across the U.S. The presentation also shows plans for analysis of the economic potential for the H2@Scale concept. Those plans involve developing supply and demand curves for potential hydrogen generation options and as compared to other options for use of that hydrogen.

  17. Methanogenic H2 syntrophy among thermophiles: a model of metabolism, adaptation and survival in the subsurface

    Science.gov (United States)

    Topcuoglu, B. D.; Stewart, L. C.; Butterfield, D. A.; Huber, J. A.; Holden, J. F.

    2016-12-01

    Approximately 1 giga ton (Gt, 1015 g) of CH4 is formed globally per year from H2, CO2 and acetate through methanogenesis, largely by methanogens growing in syntrophic association with anaerobic microbes that hydrolyze and ferment biopolymers. However, our understanding of methanogenesis in hydrothermal regions of the subseafloor and potential syntrophic methanogenesis at thermophilic temperatures (i.e., >50°C) is nascent. In this study, the growth of natural assemblages of thermophilic methanogens from Axial Seamount was primarily limited by H2 availability. Heterotrophs supported thermophilic methanogenesis by H2 syntrophy in microcosm incubations of hydrothermal fluids at 55°C and 80°C supplemented with tryptone only. Based on 16S rRNA gene sequencing, only heterotrophic archaea that produce H2, H2-consuming methanogens, and sulfate reducing archaea were found in 80°C tryptone microcosms from Marker 113 vent. No bacteria were found. In 55°C tryptone microcosms, sequences were found from H2-producing bacteria and H2-consuming methanogens and sulfate-reducing bacteria. In order to model the impact of H2 syntrophy at hyperthemophilic temperatures, a co-culture was established consisting of the H2-producing hyperthermophilic heterotroph Thermococcus paralvinellae and a H2-consuming hyperthermophilic methanogen Methanocaldococcus bathoardescens. When grown alone in a chemostat, the growth rates and steady-state cell concentrations of T. paralvinellae decreased significantly when a high H2 (70 µM) background was present. H2 inhibition was ameliorated by the production of formate, but in silico modeling suggests less energetic yield for the cells. H2 syntrophy relieved H2 inhibition for both the heterotroph and the methanogenic partners. The results demonstrate that thermophilic H2 syntrophy can support methanogenesis within natural microbial assemblages and may be an important alternative energy source for thermophilic autotrophs in marine geothermal environments.

  18. Inhibition of ethanol-producing yeast and bacteria by degradation products produced during pre-treatment of biomass

    DEFF Research Database (Denmark)

    Klinke, H.B.; Thomsen, A.B.; Ahring, Birgitte Kiær

    2004-01-01

    An overview of the different inhibitors formed by pre-treatment of lignocellulosic materials and their inhibition of ethanol production in yeast and bacteria is given. Different high temperature physical pre-treatment methods are available to render the carbohydrates in lignocellulose accessible...... degradation, phenol monomers from lignin degradation are important co-factors in hydrolysate inhibition, and inhibitory effects of these aromatic compounds on different ethanol producing microorganisms is reviewed. The furans and phenols generally inhibited growth and ethanol production rate (Q...

  19. Removal of Cadmium and Zinc from Soil using Immobilized Cell of Biosurfactant Producing Bacteria

    Directory of Open Access Journals (Sweden)

    Charoon Sarin

    2010-07-01

    Full Text Available Immobilized biosurfactant producing bacteria (Bacillus subtilis TP8 and Pseudomonas fluorescens G7 were assessed for survival in heavy metal contaminated soil and for their ability to remove cadmium and zinc from contaminated soil. P. fluorescens G7 was considered to be a good candidate for bioremediation of heavy metals because of its high minimum inhibitory concentrations (MIC for each heavy metal and because of the obviously increased numbers of cell surviving after incubation in the heavy metal contaminated soil up to 4 weeks. The results of soil remediation showed that approximately 19% of Zn and 16.7% of Cd could be removed by this immobilized biosurfactant producing bacteria after incubation for 2 weeks. The results confirm the potential applicability of the immobilized biosurfactant producing bacteria for heavy metal bioremediation.

  20. [A Case of Hyperammonemia Caused by Urinary Tract Infection Due to Urease-Producing Bacteria].

    Science.gov (United States)

    Emura, Masahiro; Tsuchihashi, Kazunari; Shimizu, Yosuke; Kanamaru, Sojun; Matoba, Shun; Ito, Noriyuki

    2016-08-01

    We present here a rare case of hyperammonemia without liver dysfunction or portal-systemic shunting. The patient was an 80-year-old woman with a history of neurogenic bladder. She was admitted to a nearby hospital for vomiting, diarrhea and consciousness disturbance. Two days after admission, she was transferred to our hospital because of persistant consciousness disturbance. Laboratory data revealed hyperammonemia, but there was no indication of liver dysfunction. Moreover abdominal computed tomography did not reveal any clear finding of liver disease or portal-systemic shunting, but we noted multiple large bladder diverticula. Antibiotic therapy, tracheal intubation, ventilator management and bladder catheterization were performed. The patient's level of consciousness improved rapidly. Urinary culture revealed Bacteroides ureolyticus (urease-producing bacteria). The patient was diagnosed with hyperammonemia and a urinary tract infection due to urease-producing bacteria. Thus, physicians should be aware that obstructive urinary tract infections due to urease-producing bacteria can also be the cause of hyperammonemia.

  1. The Ecological Role of Volatile and Soluble Secondary Metabolites Produced by Soil Bacteria.

    Science.gov (United States)

    Tyc, Olaf; Song, Chunxu; Dickschat, Jeroen S; Vos, Michiel; Garbeva, Paolina

    2016-12-27

    The rich diversity of secondary metabolites produced by soil bacteria has been appreciated for over a century, and advances in chemical analysis and genome sequencing continue to greatly advance our understanding of this biochemical complexity. However, we are just at the beginning of understanding the physicochemical properties of bacterial metabolites, the factors that govern their production and ecological roles. Interspecific interactions and competitor sensing are among the main biotic factors affecting the production of bacterial secondary metabolites. Many soil bacteria produce both volatile and soluble compounds. In contrast to soluble compounds, volatile organic compounds can diffuse easily through air- and gas-filled pores in the soil and likely play an important role in long-distance microbial interactions. In this review we provide an overview of the most important soluble and volatile classes of secondary metabolites produced by soil bacteria, their ecological roles, and their possible synergistic effects.

  2. The flocculation efficiency of compound bioflocculant by flocculant-producing bacteria

    Institute of Scientific and Technical Information of China (English)

    MA Fang; WANG Qin; MENG Lu; XU Yang; YANG Ji-xian

    2006-01-01

    The flocculation efficiency of compound bioflocculant produced by flocculant-producing bacteria was investigated in this study. Cheap cellulose was selected as the substrate for the production of a lower cost bioflocculant. The end product of cellulose decomposing bacteria was utilized as substrate for flocculant-producing bacteria. The optimum fermentation conditions were determined as follows: the initial fermentation and fermentation time was 5 d and 1 d respectively, the temperature was 30 °C, the rotation speed was 120 r/min, the amount of CaCl2 solution (10%) was 1.5 ml/L. The flocculation test indicated that the bioflocculant had high efficiency in the removal of the turbidity raw water from Songhaa River.

  3. Multiplex PCR for colony direct detection of Gram-positive histamine- and tyramine-producing bacteria.

    Science.gov (United States)

    Coton, Emmanuel; Coton, Monika

    2005-12-01

    Formation of biogenic amines (BA) may occur in fermented foods and beverages due to the amino acid decarboxylase activities of Gram-positive bacteria. These compounds may cause food poisoning and therefore could imply food exportation problems. A set of consensual primers based on histidine decarboxylase gene (hdc) sequences of different bacteria was designed for the detection of histamine-producing Gram-positive bacteria. A multiplex PCR based on these hdc primers and recently designed primers targeting the tyrosine decarboxylase (tyrdc) gene was created. A third set of primers targeting the 16S rRNA gene of eubacteria was also used as an internal control. This multiplex PCR was performed on extracted DNA as well as directly on cell colonies. The results obtained show that this new molecular tool allowed for the detection of Gram-positive histamine- and/or tyramine-producing bacteria. The use of this molecular tool for early and rapid detection of Gram-positive BA-producing bacteria is of interest in evaluating the potential of cultured indigenous strains to produce biogenic amines in a fermented food product as well as to validate the innocuity of potential starter strains in the food industry.

  4. Diversity and natural functions of antibiotics produced by beneficial and plant pathogenic bacteria.

    Science.gov (United States)

    Raaijmakers, Jos M; Mazzola, Mark

    2012-01-01

    Soil- and plant-associated environments harbor numerous bacteria that produce antibiotic metabolites with specific or broad-spectrum activities against coexisting microorganisms. The function and ecological importance of antibiotics have long been assumed to yield a survival advantage to the producing bacteria in the highly competitive but resource-limited soil environments through direct suppression. Although specific antibiotics may enhance producer persistence when challenged by competitors or predators in soil habitats, at subinhibitory concentrations antibiotics exhibit a diversity of other roles in the life history of the producing bacteria. Many processes modulated by antibiotics may be inherently critical to the producing bacterium, such as the acquisition of substrates or initiation of developmental changes that will ensure survival under stressful conditions. Antibiotics may also have roles in more complex interactions, including in virulence on host plants or in shaping the outcomes of multitrophic interactions. The innate functions of antibiotics to producing bacteria in their native ecosystem are just beginning to emerge, but current knowledge already reveals a breadth of activities well beyond the historical perspective of antibiotics as weaponry in microbial conflicts.

  5. Incidence of Bacteriocins Produced by Food-Related Lactic Acid Bacteria Active towards Oral Pathogens

    Directory of Open Access Journals (Sweden)

    Konstantinos Papadimitriou

    2013-02-01

    Full Text Available In the present study we investigated the incidence of bacteriocins produced by 236 lactic acid bacteria (LAB food isolates against pathogenic or opportunistic pathogenic oral bacteria. This set of LAB contained several strains (≥17% producing bacteriocins active against food-related bacteria. Interestingly only Streptococcus macedonicus ACA-DC 198 was able to inhibit the growth of Streptococcus oralis, Streptococcus sanguinis and Streptococcus gordonii, while Lactobacillus fermentum ACA-DC 179 and Lactobacillus plantarun ACA-DC 269 produced bacteriocins solely against Streptococcus oralis. Thus, the percentage of strains that were found to produce bacteriocins against oral bacteria was ~1.3%. The rarity of bacteriocins active against oral LAB pathogens produced by food-related LAB was unexpected given their close phylogenetic relationship. Nevertheless, when tested in inhibition assays, the potency of the bacteriocin(s of S. macedonicus ACA-DC 198 against the three oral streptococci was high. Fourier-transform infrared spectroscopy combined with principal component analysis revealed that exposure of the target cells to the antimicrobial compounds caused major alterations of key cellular constituents. Our findings indicate that bacteriocins produced by food-related LAB against oral LAB may be rare, but deserve further investigation since, when discovered, they can be effective antimicrobials.

  6. Infrared absorption of t-HOCO+, H+(CO2)2, and HCO2- produced in electron bombardment of CO2 in solid para-H2

    Science.gov (United States)

    Das, Prasanta; Tsuge, Masashi; Lee, Yuan-Pern

    2016-07-01

    We have employed electron bombardment during matrix deposition of CO2 (or 13CO2, C18O2) and para-hydrogen (p-H2) at 3.2 K and recorded infrared (IR) spectra of t-HOCO+, H+(CO2)2, HCO2-, CO2-, t-HOCO, and other species isolated in solid p-H2. After the matrix was maintained in darkness for 13 h, intensities of absorption features of t-HOCO+ at 2403.5 (ν1), 2369.9 (ν2), 1018.1 (ν4), and 606.5 (ν6) cm-1 and those of H+(CO2)2 at 1341.1, 883.6, and 591.5 cm-1 decreased. Corresponding lines of isotopologues were observed when 13CO2 or C18O2 replaced CO2. In contrast, lines of HCO2- at 2522.4 (ν1), 1616.1 (ν5), 1327.9 (ν2), and 745.6 (ν3) cm-1 increased in intensity; corresponding lines of H13CO2- or HC18O2- were also observed. Lines of t-DOCO+ and DCO2- were observed in an electron bombarded CO2 /normal-deuterium (n-D2) matrix. Data of ν6 of t-HOCO+ and all observed modes of H18OC18O+ and HC18O2- are new. The assignments were made according to expected chemical behavior, observed isotopic shifts, and comparisons with vibrational wavenumbers and relative intensities of previous reports and calculations with the B3PW91/aug-cc-pVQZ method. The ν1 line of t-HOCO+ in solid p-H2 (2403.5 cm-1), similar to the line at 2673 cm-1 of t-HOCO+ tagged with an Ar atom, is significantly red-shifted from that reported for gaseous t-HOCO+ (3375.37 cm-1) due to partial proton sharing between CO2 and H2 or Ar. The ν1 line of HCO2- in solid p-H2 (2522.4 cm-1) is blue shifted from that reported for HCO2- in solid Ne (2455.7 cm-1) and that of HCO2- tagged with Ar (2449 cm-1); this can be explained by the varied solvation effects by Ne, Ar, or H2 on the mixing of H+ + CO2 and H + CO2- surfaces. Possible formation mechanisms of t-HOCO+, H+(CO2)2, HCO2-, CO2-, t-HOCO, H2O, and t-HCOOH are discussed.

  7. Presence of antimicrobial resistance in coliform bacteria from hatching broiler eggs with emphasis on ESBL/AmpC-producing bacteria.

    Science.gov (United States)

    Mezhoud, H; Chantziaras, I; Iguer-Ouada, M; Moula, N; Garmyn, A; Martel, A; Touati, A; Smet, A; Haesebrouck, F; Boyen, F

    2016-08-01

    Antimicrobial resistance is recognized as one of the most important global health challenges. Broilers are an important reservoir of antimicrobial resistant bacteria in general and, more particularly, extended-spectrum β-lactamases (ESBL)/AmpC-producing Enterobacteriaceae. Since contamination of 1-day-old chicks is a potential risk factor for the introduction of antimicrobial resistant Enterobacteriaceae in the broiler production chain, the presence of antimicrobial resistant coliform bacteria in broiler hatching eggs was explored in the present study. Samples from 186 hatching eggs, collected from 11 broiler breeder farms, were inoculated on MacConkey agar with or without ceftiofur and investigated for the presence of antimicrobial resistant lactose-positive Enterobacteriaceae, particularly, ESBL/AmpC-producers. Escherichia coli and Enterobacter cloacae were obtained from the eggshells in 10 out of 11 (10/11) sampled farms. The majority of the isolates were recovered from crushed eggshells after external decontamination suggesting that these bacteria are concealed from the disinfectants in the egg shell pores. Antimicrobial resistance testing revealed that approximately 30% of the isolates showed resistance to ampicillin, tetracycline, trimethoprim and sulphonamides, while the majority of isolates were susceptible to amoxicillin-clavulanic acid, nitrofurantoin, aminoglycosides, florfenicol, neomycin and apramycin. Resistance to extended-spectrum cephalosporins was detected in eight Enterobacteriaceae isolates from five different broiler breeder farms. The ESBL phenotype was confirmed by the double disk synergy test and blaSHV-12, blaTEM-52 and blaACT-39 resistance genes were detected by PCR. This report is the first to present broiler hatching eggs as carriers and a potential source of ESBL/AmpC-producing Enterobacteriaceae for broiler chicks.

  8. Effects of biosurfactant-producing bacteria on biodegradation and transport of phenanthrene in subsurface soil.

    Science.gov (United States)

    Chang, Jae-Soo; Cha, Daniel K; Radosevich, Mark; Jin, Yan

    2015-01-01

    This study investigated the effects of surfactant-producing microorganism, Pseudomonas aeruginosa ATCC 9027, on phenanthrene (PHE) biodegradation by two different PHE-degrading bacteria (Isolate P5-2 and Pseudomonas strain R) in soil. Phenanthrene mineralization experiments were conducted with soils inoculated with one of PHE-degraders and/or the surfactant-producer. Influence of co-inoculation with the surfactant-producing bacteria on phenanthrene transport and biodegradation was also examined in soil columns. P. strain R mineralized phenanthrene faster and to a greater extent than Isolate P5-2 in the test soil. Co-inoculation with the surfactant-producing bacteria significantly enhanced phenanthrene biodegradation by P. strain R but it did not affect the biodegradation by Isolate P5-2 in both batch and column systems. Production of biosurfactants by P. aeruginosa ATCC 9027 was negligible under the given conditions. This study demonstrated that bioaugmentation with surfactant-producing bacteria could enhance in situ bioremediation of soils contaminated with polycyclic aromatic hydrocarbons (PAHs) and the beneficial effect of the bioaugmentation depended on types of PAH-degrading microorganisms present.

  9. Exploration of indigenous soil bacteria producing-exopolysaccharides for stabilizing of aggregates land potential as biofertilizer

    Directory of Open Access Journals (Sweden)

    N Arfarita

    2016-10-01

    Full Text Available Steady soil aggregationis important for agricultural land which is formed by the micro-aggregate to become a macro-aggregate. This formation is mediated by organic material and various kinds of macro-organisms such as fungi, worms, ants and insects. An organic agencyinvolved in soil aggregation stabilityis exopolysaccharide (EPS derived from bacterial, fungal mycelium, and products synthesized by plants. However, the use of EPS producing microorganisms as a biofertilizer has not been reported. This study was aimedto explore indigenous EPS-producing bacteria to solidify soil aggregationpotential for biofertilizer. Bacterial strains were isolated from soilsofthree regions at Malang East-Java; two areas of green bean plantation in Kendal Payak and Jambe Gede, as well as forest land. Soil samplewas derived from forest had hasa total bacteria population of 9.3 x 1011 CFU/mL.While soil samples from area Kendal Payak and Jambe Gede had total bacteria population of 1.5 x 109 CFU/mL and 2.4 x 109 CFU/mL, respectively. We selected three bacteria that could potentially produce abundant slime, namely as SPE-2, SPE-10 and SPE-20. The three selected bacteria are potential for biofertilizer because oftheir abundant slime, no antagonism and no symtoms as pathogen.

  10. Bioactive Compound Rich Indian Spices Suppresses the Growth of β-lactamase Produced Multidrug Resistant Bacteria

    Directory of Open Access Journals (Sweden)

    Eadlapalli Siddhartha

    2017-01-01

    Full Text Available Background: Multidrug Resistance (MDR among bacteria become a global concern due to failure of antibiotics, is drawn attention for best antimicrobials from the spices which have been using ancient days in Indian culinary and traditional medicine. Aim and Objectives: The present study was undertaken to evaluate the bioactive compounds and their antibacterial activity in routinely used culinary Indian spices against β-lactamase produced MDR bacteria. Material and Methods: Ethanolic extracts prepared from twenty spices and were evaluated for total phenolics, flavonoids, alkaloids, terpenoids, antioxidant properties, and also assayed their antibacterial activities against β-lactamase producing MDR bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. β-Lactamase and cell viability assays were performed in MDR bacteria. Results: Among twenty spices, cinnamon and clove exhibited highest levels of phenolics and terpenoids with elevated antioxidant potential and also showing greater reducing potential at lower concentrations of extract (2.3 and 4.06 µg GAE/gm, respectively. Further, the spices extracts were assessed for antimicrobial activity against β-lactamase produced tested MDR bacteria and observed higher antimicrobial activity with cinnamon, garlic, tamarind and clove at lowest concentrations of MIC and MBC at 16 - 32 µg GAE/ml, as compared to standard drug, amoxiclav (16/8 µg/ml. Spices significantly inhibited the β-lactamase activity (80–94% and also cell viability in tested MDR bacteria. Conclusion: Indian spices consist of rich bioactive profile and antioxidant activity inhibited the bacterial growth effectively by suppressing β-lactamase production in MDR bacteria. Results indicating the spices as functional foods and could be used in prevention of antibiotic resistance.

  11. [Bioaugmentation of hydrogen producing bacteria on operation of bio-hydrogen producing reactor].

    Science.gov (United States)

    Qin, Zhi; Ren, Nan-qi; Li, Jian-zheng

    2007-12-01

    Hydrogen producing strain Ethanoligenens sp. B49 was inoculated into activated sludge of continuous stirred tank reactor (CSTR)to bioaugment hydrogen production. Hydrogen production capacities, compositions of fermentation products and pH value before and after bioaugmentation were investigated. When organic loading rate was 12 kg/(m3 x d), bioaugmentation of hydrogen producing strain enhanced hydrogen production rate and improved the composition of fermentation products significantly. After bioaugmentation, hydrogen production rate increased from 3.6 mmol/(kg x d) to 5.7 mmol/(kg x d), which was 1.5 times as that before bioaugmentation. Before bioaugmentation, average concentration of ethanol, acetic acid and propionic acid were 6.8 mmol/L, 5.3 mmol/L, 4.8 mmol/L respectively, while after bioaugmentation, those were 10.5 mmol/L, 7.5 mmol/L and 1.7 mmol/L respectively. Ethanol and acetic acid accounted for 86.8% in total fermentative products after bioaugmentation, while only 72% before bioaugmentation. pH value of effluent dropped from 4.5-4.7 to 4.3. Bioaugmentation of hydrogen producing strain is helpful to promote the formation of ethanol-type fermentation in low organic loading rate.

  12. HCN Producing Bacteria Enable Sensing Of Non-Bioavailable Hg Species by the Whole Cell Biosensor

    Science.gov (United States)

    Horvat, M.; Rijavec, T.; Koron, N.; Lapanje, A.

    2015-12-01

    Bacteria play an important role in Hg transformation reactions. The production of cyanide (HCN) and other secondary metabolites seems to be key elements involved in these transformations. Current hypotheses link the role of HCN production to growth inhibition of nonHCN producing competitor organisms (role of an antimicrobial agent). Our past investigations showed that HCN production did not correlate with antimicrobial activity and since pK value of HCN is very high (pK = 9,21), it can be expected that most of the produced HCN is removed from the microenvironment. This way, the expected inhibitory concentrations can hardly be reached. Accordingly, we proposed a new concept, where the ability of complexation of transient metals by HCN served as a regulation process for the accessibility of micro-elements. In our study, we focused on the presence of HCN producing bacteria and carried it out in the Hg contaminated environment connected to the Idrija Mercury Mine, Slovenia. We characterised the isolates according to the presence of Hg resistance (HgR), level of HCN production and genetic similarities. In laboratory setups, using our merR whole cell based biosensor, we determined the transformation of low bioavailable Hg0 and HgS forms into bioavailable Hg by these HCN producing bacteria. We observed that HgR strains producing HCN had the highest impact on increased Hg bioavailability. In the proposed ecological strategy HgR HCN producing bacteria increase their competitive edge over non-HgR competitors through the increase of Hg toxicity. Due to their activity, Hg is made available to other organisms as well and thus enters into the ecosystem. Finally, using some of the characteristics of bacteria (e.g. Hg resistance genetic elements), we developed a fully automated sensing approach, combining biosensorics and mechatronics, to measure the bioavailability of Hg in situ.

  13. Bioleaching of metals from printed circuit boards supported with surfactant-producing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Karwowska, Ewa, E-mail: ewa.karwowska@is.pw.edu.pl [Warsaw University of Technology, Faculty of Environmental Engineering, Biology Division, Nowowiejska 20, 00-653 Warsaw (Poland); Andrzejewska-Morzuch, Dorota; Łebkowska, Maria [Warsaw University of Technology, Faculty of Environmental Engineering, Biology Division, Nowowiejska 20, 00-653 Warsaw (Poland); Tabernacka, Agnieszka, E-mail: agnieszka.tabernacka@is.pw.edu.pl [Warsaw University of Technology, Faculty of Environmental Engineering, Biology Division, Nowowiejska 20, 00-653 Warsaw (Poland); Wojtkowska, Małgorzata; Telepko, Alicja; Konarzewska, Agnieszka [Warsaw University of Technology, Faculty of Environmental Engineering, Nowowiejska 20, 00-653 Warsaw (Poland)

    2014-01-15

    Highlights: • Bioleaching of metals from printed circuit boards by BSAC-producing bacteria was estimated. • Aeration increased the release of all metals in medium with sulphur and biosurfactant. • Increase in Cu, Pb, Ni and Cr removal rate was observed at 37 °C in acidic medium. -- Abstract: This study has evaluated the possibility of bioleaching zinc, copper, lead, nickel, cadmium and chromium from printed circuit boards by applying a culture of sulphur-oxidising bacteria and a mixed culture of biosurfactant-producing bacteria and sulphur-oxidising bacteria. It was revealed that zinc was removed effectively both in a traditional solution acidified by a way of microbial oxidation of sulphur and when using a microbial culture containing sulphur-oxidising and biosurfactant-producing bacteria. The average process efficiency was 48% for Zn dissolution. Cadmium removal was similar in both media, with a highest metal release of 93%. For nickel and copper, a better effect was obtained in the acidic medium, with a process effectiveness of 48.5% and 53%, respectively. Chromium was the only metal that was removed more effectively in the bioleaching medium containing both sulphur-oxidising and biosurfactant-producing bacteria. Lead was removed from the printed circuit boards with very low effectiveness (below 0.5%). Aerating the culture medium with compressed air increased the release of all metals in the medium with sulphur and biosurfactant, and of Ni, Cu, Zn and Cr in the acidic medium. Increasing the temperature of the medium (to 37 °C) had a more significant impact in the acidic environment than in the neutral environment.

  14. Searching for branched glycerol dialkyl glycerol tetraether membrane lipid producing bacteria in soil

    NARCIS (Netherlands)

    Aydin, R.

    2012-01-01

    KEYWORDS:Branched GDGTs, proxy, pH, temperature, Acidobacteria, methylotrophy, high-throughput techniques Bacteria present in soil and peat bog environments were previously found to produce branched glycerol dialkyl glycerol tetraether membrane lip

  15. Glucansucrases from lactic acid bacteria which produce water-insoluble polysaccharides from sucrose

    Science.gov (United States)

    Dextrans and related glucans produced from sucrose by lactic acid bacteria have been studied for many years and are used in numerous commercial applications and products. Most of these glucans are water-soluble, except for a few notable exceptions from cariogenic Streptococcus spp. and a very small ...

  16. Glycosaminoglycan-depolymerizing enzymes produced by anaerobic bacteria isolated from the human mouth.

    Science.gov (United States)

    Tipler, L S; Embery, G

    1985-01-01

    A number of obligately anaerobic bacteria, some implicated in periodontal disease, were screened for their ability to produce enzymes capable of degrading hyaluronic acid and chondroitin-4-sulphate. Two screening methods were used following anaerobic incubation at 37 degrees C for 7 days. One involved incorporating the respective substrates and bovine-serum albumin into agar plates and, after incubation, flooding the plates with 2 M acetic acid. Clear zones were produced around colonies which produced enzymes capable of depolymerizing the substrates. The second was a sensitive spectrophotometric procedure based on the ability of certain bacteria to produce eliminase enzymes, which degrade the substrates to unsaturated products having a characteristic u.v. absorption at 232 nm. Strains of Bacteroides gingivalis and Bacteroides melaninogenicus degraded both substrates whereas Bacteroides asaccharolyticus degraded neither substrate by either method. Some bacteria gave negative results with the plate method whereas the more sensitive spectrophotometric assay proved positive. The number of anaerobic bacteria capable of degrading hyaluronic acid and chondroitin-4-sulphate in vitro may therefore have been underestimated in previous studies.

  17. Diversity and natural functions of antibiotics produced by beneficial and plant pathogenic bacteria

    NARCIS (Netherlands)

    Raaijmakers, J.M.; Mazzola, M.

    2012-01-01

    Soil- and plant-associated environments harbor numerous bacteria that produce antibiotic metabolites with specific or broad-spectrum activities against coexisting microorganisms. The function and ecological importance of antibiotics have long been assumed to yield a survival advantage to the produci

  18. Diversity and natural functions of antibiotics produced by beneficial and plant pathogenic bacteria

    NARCIS (Netherlands)

    Raaijmakers, J.M.; Mazzola, M.

    2012-01-01

    Soil- and plant-associated environments harbor numerous bacteria that produce antibiotic metabolites with specific or broad-spectrum activities against coexisting microorganisms. The function and ecological importance of antibiotics have long been assumed to yield a survival advantage to the produci

  19. Diversity and natural functions of antibiotics produced by beneficial and plant pathogenic bacteria

    NARCIS (Netherlands)

    Raaijmakers, J.M.; Mazzola, M.

    2012-01-01

    Soil- and plant-associated environments harbor numerous bacteria that produce antibiotic metabolites with specific or broad-spectrum activities against coexisting microorganisms. The function and ecological importance of antibiotics have long been assumed to yield a survival advantage to the

  20. Analysis of 16S rRNA gene lactic acid bacteria (LAB) isolate from Markisa fruit (Passiflora sp.) as a producer of protease enzyme and probiotics

    Science.gov (United States)

    Hidayat, Habibi

    2017-03-01

    16S rRNA gene analysis of bacteria lactic acid (LAB) isolate from Markisa Kuning Fruit (Passiflora edulis var. flavicarpa) as a producer of protease enzyme and probiotics has been done. The aim of the study is to determine the protease enzyme activity and 16S rRNA gene amplification using PCR. The calculation procedure was done to M4 isolate bacteria lactic acid (LAB) Isolate which has been resistant to acids with pH 2.0 in the manner of screening protease enzyme activity test result 6.5 to clear zone is 13 mm againts colony diametre is 2 mm. The results of study enzyme activity used spectrophotometer UV-Vis obtainable the regression equation Y=0.02983+0.001312X, with levels of protein M4 isolate is 0.6594 mg/mL and enzyme activity of obtainable is 0.8626 unit/ml while the spesific enzyme activity produced is 1.308 unit/mg. Then, 16S rRNA gene amplificatiom and DNA sequencing has been done. The results of study showed that the bacteria species contained from M4 bacteria lactic acid (LAB) isolate is Weisella cibiria strain II-I-59. Weisella cibiria strain II-I-59 is one of bacteria could be utilized in the digestive tract.

  1. PCR detection of foodborne bacteria producing the biogenic amines histamine, tyramine, putrescine, and cadaverine.

    Science.gov (United States)

    de las Rivas, Blanca; Marcobal, Angela; Carrascosa, Alfonso V; Muñoz, Rosario

    2006-10-01

    This study describes an easy PCR method for the detection of foodborne bacteria that potentially produce histamine, tyramine, putrescine, and cadaverine. Synthetic oligonucleotide pairs for the specific detection of the gene coding for each group of bacterial histidine, tyrosine, ornithine, or lysine decarboxylases were designed. Under the conditions used in this study, the assay yielded fragments of 372 and 531 bp from histidine decarboxylase-encoding genes, a 825-bp fragment from tyrosine decarboxylases, fragments of 624 and 1,440 bp from ornithine decarboxylases, and 1,098- and 1,185-bp fragments from lysine decarboxylases. This is the first PCR method for detection of cadaverine-producing bacteria. The method was successfully applied to several biogenic amine-producing bacterial strains.

  2. High-Level Culturability of Epiphytic Bacteria and Frequency of Biosurfactant Producers on Leaves

    Science.gov (United States)

    Burch, Adrien Y.; Do, Paulina T.; Sbodio, Adrian; Suslow, Trevor V.

    2016-01-01

    ABSTRACT To better characterize the bacterial community members capable of biosurfactant production on leaves, we distinguished culturable biosurfactant-producing bacteria from nonproducers and used community sequencing to compare the composition of these distinct cultured populations with that from DNA directly recovered from leaves. Communities on spinach, romaine, and head lettuce leaves were compared with communities from adjacent samples of soil and irrigation source water. Soil communities were poorly described by culturing, with recovery of cultured representatives from only 21% of the prevalent operational taxonomic units (OTUs) (>0.2% reads) identified. The dominant biosurfactant producers cultured from soil included bacilli and pseudomonads. In contrast, the cultured communities from leaves are highly representative of the culture-independent communities, with over 85% of the prevalent OTUs recovered. The dominant taxa of surfactant producers from leaves were pseudomonads as well as members of the infrequently studied genus Chryseobacterium. The proportions of bacteria cultured from head lettuce and romaine leaves that produce biosurfactants were directly correlated with the culture-independent proportion of pseudomonads in a given sample, whereas spinach harbored a wider diversity of biosurfactant producers. A subset of the culturable bacteria in irrigation water also became enriched on romaine leaves that were irrigated overhead. Although our study was designed to identify surfactant producers on plants, we also provide evidence that most bacteria in some habitats, such as agronomic plant surfaces, are culturable, and these communities can be readily investigated and described by more classical culturing methods. IMPORTANCE The importance of biosurfactant production to the bacteria that live on waxy leaf surfaces as well as their ability to be accurately assessed using culture-based methodologies was determined by interrogating epiphytic populations by

  3. Potential of BAC combined with UVC/H2O2 for reducing organic matter from highly saline reverse osmosis concentrate produced from municipal wastewater reclamation.

    Science.gov (United States)

    Lu, Jie; Fan, Linhua; Roddick, Felicity A

    2013-10-01

    The organic matter present in the concentrate streams generated from reverse osmosis (RO) based municipal wastewater reclamation processes poses environmental and health risks on its disposal to the receiving environment (e.g., estuaries, bays). The potential of a biological activated carbon (BAC) process combined with pre-oxidation using a UVC/H2O2 advanced oxidation process for treating a high salinity (TDS~10000 mg L(-1)) municipal wastewater RO concentrate (ROC) was evaluated at lab scale during 90 d of operation. The combined treatment reduced the UVA254 and colour of the ROC to below those for the influent of the RO process (i.e., biologically treated secondary effluent), and the reductions in DOC and COD were approximately 60% and 50%, respectively. UVC/H2O2 was demonstrated to be an effective means of converting the recalcitrant organic compounds in the ROC into biodegradable substances which were readily removed by the BAC process, leading to a synergistic effect of the combined treatment in degrading the organic matter. The tests using various BAC feed concentrations suggested that the biological treatment was robust and consistent for treating the high salinity ROC. Using Microtox analysis no toxicity was detected for the ROC after the combined treatment, and the trihalomethane formation potential was reduced from 3.5 to 2.8 mg L(-1). Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Nucleobases and Prebiotic Molecules in Organic Residues Produced from the Ultraviolet Photo-Irradiation of Pyrimidine in NH3 and H2O+NH3 Ices

    Science.gov (United States)

    Nuevo, Michel; Milam, Stefanie N.; Sandford, Scott

    2012-01-01

    Although not yet identified in the interstellar medium (ISM), N-heterocycles including nucleobases the information subunits of DNA and RNA are present in carbonaceous chondrites, which indicates that molecules of biological interest can be formed in non-terrestrial environments via abiotic pathways. Recent laboratory experiments and ab-initio calculations have already shown that the irradiation of pyrimidine in pure H2O ices leads to the formation of a suite of oxidized pyrimidine derivatives, including the nucleobase uracil. In the present work, NH3:pyrimidine and H2O:NH3:pyrimidine ice mixtures with different relative proportions were irradiated with UV photons under astrophysically relevant conditions. Liquid- and gas-chromatography analysis of the resulting organic residues has led to the detection of the nucleobases uracil and cytosine, as well as other species of prebiotic interest such as urea and small amino acids. The presence of these molecules in organic residues formed under abiotic conditions supports scenarios in which extraterrestrial organics that formed in space and were subsequently delivered to telluric planets via comets and meteorites could have contributed to the inventory of molecules that triggered the first biological reactions on their surfaces.

  5. Gut-Colonizing Bacteria Promote C. elegans Innate Immunity by Producing Nitric Oxide

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    Yi Xiao

    2016-02-01

    Full Text Available Many commensal bacteria in the gut are beneficial to the host immune system, but the underlying mechanisms are largely unclear. Using culture-independent Illumina MiSeq sequencing of the bacterial 16S rRNA gene amplicons, we show that bacterial diversity in the intestine of Caenorhabditis elegans, the free-living nematode, is distinct from that in soil. Of these bacteria, Bacillus subtilis is the most prominent species in the worm gut. We demonstrate that B. subtilis confers worm resistance to infection by pathogenic bacteria, such as Pseudomonas aeruginosa, Salmonella enterica, and Enterococcus faecalis, by producing nitric oxide (NO. Deletion of the nos gene, which encodes an NO synthase, reduces the protective effect. NO promotes innate immune responses to P. aeruginosa PA14 by activating a conserved p38 mitogen protein kinase (MAPK in C. elegans. Our work provides an example of antagonism of commensal bacteria against pathogens and illustrates the importance of commensal bacteria in host immunity.

  6. Differential attraction of malaria mosquitoes to volatile blends produced by human skin bacteria.

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    Niels O Verhulst

    Full Text Available The malaria mosquito Anopheles gambiae sensu stricto is mainly guided by human odour components to find its blood host. Skin bacteria play an important role in the production of human body odour and when grown in vitro, skin bacteria produce volatiles that are attractive to A. gambiae. The role of single skin bacterial species in the production of volatiles that mediate the host-seeking behaviour of mosquitoes has remained largely unknown and is the subject of the present study. Headspace samples were taken to identify volatiles that mediate this behaviour. These volatiles could be used as mosquito attractants or repellents. Five commonly occurring species of skin bacteria were tested in an olfactometer for the production of volatiles that attract A. gambiae. Odour blends produced by some bacterial species were more attractive than blends produced by other species. In contrast to odours from the other bacterial species tested, odours produced by Pseudomonas aeruginosa were not attractive to A. gambiae. Headspace analysis of bacterial volatiles in combination with behavioural assays led to the identification of six compounds that elicited a behavioural effect in A. gambiae. Our results provide, to our knowledge, the first evidence for a role of selected bacterial species, common on the human skin, in determining the attractiveness of humans to malaria mosquitoes. This information will be used in the further development of a blend of semiochemicals for the manipulation of mosquito behaviour.

  7. Differential Attraction of Malaria Mosquitoes to Volatile Blends Produced by Human Skin Bacteria

    Science.gov (United States)

    Verhulst, Niels O.; Andriessen, Rob; Groenhagen, Ulrike; Bukovinszkiné Kiss, Gabriella; Schulz, Stefan; Takken, Willem; van Loon, Joop J. A.; Schraa, Gosse; Smallegange, Renate C.

    2010-01-01

    The malaria mosquito Anopheles gambiae sensu stricto is mainly guided by human odour components to find its blood host. Skin bacteria play an important role in the production of human body odour and when grown in vitro, skin bacteria produce volatiles that are attractive to A. gambiae. The role of single skin bacterial species in the production of volatiles that mediate the host-seeking behaviour of mosquitoes has remained largely unknown and is the subject of the present study. Headspace samples were taken to identify volatiles that mediate this behaviour. These volatiles could be used as mosquito attractants or repellents. Five commonly occurring species of skin bacteria were tested in an olfactometer for the production of volatiles that attract A. gambiae. Odour blends produced by some bacterial species were more attractive than blends produced by other species. In contrast to odours from the other bacterial species tested, odours produced by Pseudomonas aeruginosa were not attractive to A. gambiae. Headspace analysis of bacterial volatiles in combination with behavioural assays led to the identification of six compounds that elicited a behavioural effect in A. gambiae. Our results provide, to our knowledge, the first evidence for a role of selected bacterial species, common on the human skin, in determining the attractiveness of humans to malaria mosquitoes. This information will be used in the further development of a blend of semiochemicals for the manipulation of mosquito behaviour. PMID:21209854

  8. Graphene oxide and H2 production from bioelectrochemical graphite oxidation.

    Science.gov (United States)

    Lu, Lu; Zeng, Cuiping; Wang, Luda; Yin, Xiaobo; Jin, Song; Lu, Anhuai; Jason Ren, Zhiyong

    2015-11-17

    Graphene oxide (GO) is an emerging material for energy and environmental applications, but it has been primarily produced using chemical processes involving high energy consumption and hazardous chemicals. In this study, we reported a new bioelectrochemical method to produce GO from graphite under ambient conditions without chemical amendments, value-added organic compounds and high rate H2 were also produced. Compared with abiotic electrochemical electrolysis control, the microbial assisted graphite oxidation produced high rate of graphite oxide and graphene oxide (BEGO) sheets, CO2, and current at lower applied voltage. The resultant electrons are transferred to a biocathode, where H2 and organic compounds are produced by microbial reduction of protons and CO2, respectively, a process known as microbial electrosynthesis (MES). Pseudomonas is the dominant population on the anode, while abundant anaerobic solvent-producing bacteria Clostridium carboxidivorans is likely responsible for electrosynthesis on the cathode. Oxygen production through water electrolysis was not detected on the anode due to the presence of facultative and aerobic bacteria as O2 sinkers. This new method provides a sustainable route for producing graphene materials and renewable H2 at low cost, and it may stimulate a new area of research in MES.

  9. The role of beta-lactamase-producing-bacteria in mixed infections

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    Brook Itzhak

    2009-12-01

    Full Text Available Abstract Beta-lactamase-producing bacteria (BLPB can play an important role in polymicrobial infections. They can have a direct pathogenic impact in causing the infection as well as an indirect effect through their ability to produce the enzyme beta-lactamase. BLPB may not only survive penicillin therapy but can also, as was demonstrated in in vitro and in vivo studies, protect other penicillin-susceptible bacteria from penicillin by releasing the free enzyme into their environment. This phenomenon occurs in upper respiratory tract, skin, soft tissue, surgical and other infections. The clinical, in vitro, and in vivo evidence supporting the role of these organisms in the increased failure rate of penicillin in eradication of these infections and the implication of that increased rate on the management of infections is discussed.

  10. Severity of atopic disease inversely correlates with intestinal microbiota diversity and butyrate-producing bacteria.

    Science.gov (United States)

    Nylund, L; Nermes, M; Isolauri, E; Salminen, S; de Vos, W M; Satokari, R

    2015-02-01

    The reports on atopic diseases and microbiota in early childhood remain contradictory, and both decreased and increased microbiota diversity have been associated with atopic eczema. In this study, the intestinal microbiota signatures associated with the severity of eczema in 6-month-old infants were characterized. Further, the changes in intestinal microbiota composition related to the improvement of this disease 3 months later were assessed. The severity of eczema correlated inversely with microbiota diversity (r = -0.54, P = 0.002) and with the abundance of butyrate-producing bacteria (r = -0.52, P = 0.005). During the 3-month follow-up, microbiota diversity increased (P microbiota and high abundance of butyrate-producing bacteria were associated with milder eczema, thus suggesting they have a role in alleviating symptoms of atopic eczema.

  11. Antibiotic-producing bacteria from the sea surface microlayer in the Trondheim fjord, Norway

    OpenAIRE

    Hakvåg, Sigrid

    2009-01-01

    The marine environment has so far been poorly utilized in the search for (producers of) novel antimicrobial compounds. Marine bioprospecting might therefore be a promising field of research for the pharmaceutical industry as an alternative to terrestrial sources and synthetic production of pharmaceuticals.In this project, over 4000 cultivable isolates have been isolated from different locations in the Trondheim fjord and along the coast of Trøndelag, Norway. Over 1000 of these bacteria were i...

  12. Removal of Cadmium and Zinc from Soil using Immobilized Cell of Biosurfactant Producing Bacteria

    OpenAIRE

    Charoon Sarin; Siripun Sarin

    2010-01-01

    Immobilized biosurfactant producing bacteria (Bacillus subtilis TP8 and Pseudomonas fluorescens G7) were assessed for survival in heavy metal contaminated soil and for their ability to remove cadmium and zinc from contaminated soil. P. fluorescens G7 was considered to be a good candidate for bioremediation of heavy metals because of its high minimum inhibitory concentrations (MIC) for each heavy metal and because of the obviously increased numbers of cell surviving after incubation in the hea...

  13. High-Level Culturability of Epiphytic Bacteria and Frequency of Biosurfactant Producers on Leaves

    OpenAIRE

    Burch, AY; Do, PT; Sbodio, A; Suslow, TV; Lindow, SE

    2016-01-01

    To better characterize the bacterial community members capable of biosurfactant production on leaves, we distinguished culturable biosurfactant-producing bacteria from nonproducers and used community sequencing to compare the composition of these distinct cultured populations with that from DNA directly recovered from leaves. Communities on spinach, romaine, and head lettuce leaves were compared with communities from adjacent samples of soil and irrigation source water. Soil communities were ...

  14. H2@Scale Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    Pivovar, Bryan

    2017-03-31

    Final report from the H2@Scale Workshop held November 16-17, 2016, at the National Renewable Energy Laboratory in Golden, Colorado. The U.S. Department of Energy's National Renewable Energy Laboratory hosted a technology workshop to identify the current barriers and research needs of the H2@Scale concept. H2@Scale is a concept regarding the potential for wide-scale impact of hydrogen produced from diverse domestic resources to enhance U.S. energy security and enable growth of innovative technologies and domestic industries. Feedback received from a diverse set of stakeholders at the workshop will guide the development of an H2@Scale roadmap for research, development, and early stage demonstration activities that can enable hydrogen as an energy carrier at a national scale.

  15. EMULSAN ANALYSIS PRODUCED BY LOCALLY ISOLATED BACTERIA AND ACINETOBACTER CALCOACETICUS RAG-1

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    P. Chamanrokh, M. Mazaheri Assadi, A. Noohi, S. Yahyai

    2008-04-01

    Full Text Available Growth of previously isolated bacteria from Iranian oil reservoirs on different carbon and energy sources and under varying conditions have been used to produce a class of extracellular microbial protein-associated lipopolysaccharides named emulsan.Several Bacteria were previously isolated from Iranian oil reservoirs and designated as; Ilam-1 and Paydar-4. In present study, the isolated strains were compared with standard sample of Acinetobacter calcoaceticus RAG-1 from Persian Type Culture Collection (PTCC 1641, IROST. Among the isolated strains, two strains were found to produce an extracellular, emulsifying agent when grown in Mineral Salt Medium containing soya oil, ethanol or local crude oil. The isolated bacteria were cultured and further analysed using protein estimation, reducing sugar analysis, hemolytic activity, surface tension and emulsification activity tests. The crude emulsifier of RAG-1, PAYDAR-4 and ILAM-1 were concentrated from the cell-free culture fluid by ammonium sulfate precipitation to yield 1.89g, 1.78g and 1.69g of bioemulsan respectively. Emulsifying activity was observed over the entire production process. These investigations showed that emulsan produced by isolated Iranian crude oil reservoir were comparable with Acinetobacter calcoaceticus RAG-1 which is made of carbohydrate backbone as its hydrophilic part (N-acetyl-D-galactoseamine, N-acetylgalactoseamine uronic acid, diamino-6-deoxy-D-glucose and fatty acid chain as its hydrophobic portion.

  16. A glutamic acid-producing lactic acid bacteria isolated from Malaysian fermented foods.

    Science.gov (United States)

    Zareian, Mohsen; Ebrahimpour, Afshin; Bakar, Fatimah Abu; Mohamed, Abdul Karim Sabo; Forghani, Bita; Ab-Kadir, Mohd Safuan B; Saari, Nazamid

    2012-01-01

    l-glutamaic acid is the principal excitatory neurotransmitter in the brain and an important intermediate in metabolism. In the present study, lactic acid bacteria (218) were isolated from six different fermented foods as potent sources of glutamic acid producers. The presumptive bacteria were tested for their ability to synthesize glutamic acid. Out of the 35 strains showing this capability, strain MNZ was determined as the highest glutamic-acid producer. Identification tests including 16S rRNA gene sequencing and sugar assimilation ability identified the strain MNZ as Lactobacillus plantarum. The characteristics of this microorganism related to its glutamic acid-producing ability, growth rate, glucose consumption and pH profile were studied. Results revealed that glutamic acid was formed inside the cell and excreted into the extracellular medium. Glutamic acid production was found to be growth-associated and glucose significantly enhanced glutamic acid production (1.032 mmol/L) compared to other carbon sources. A concentration of 0.7% ammonium nitrate as a nitrogen source effectively enhanced glutamic acid production. To the best of our knowledge this is the first report of glutamic acid production by lactic acid bacteria. The results of this study can be further applied for developing functional foods enriched in glutamic acid and subsequently γ-amino butyric acid (GABA) as a bioactive compound.

  17. Effect of diazotrophic bacteria as phosphate solubilizing and indolic compound producers on maize plants

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    Mónica Del Pilar López Ortega

    2013-12-01

    Full Text Available Phosphorus is limiting for growth of maize plants, and because of that use of fertilizers like Rock Phosphate has been proposed. However, direct use of Rock Phosphate is not recommended because of its low availability, so it is necessary to improve it. In this study, a group of diazotrophic bacteria were evaluated as phosphate-solubilizing bacteria, for their production of indolic compounds and for their effects on growth of maize plants. Strains of the genera Azosporillum, Azotobacter, Rhizobium and Klebsiella, were quantitatively evaluated for solubilization of Ca3(PO42 and rock phosphate as a single source of phosphorous in SRS culture media. Additionally, the phosphatase enzyme activity was quantified at pH 5.0, 7.0 and 8.0 using p-nitrophenyl phosphate, and production of indolic compound was determined by colorimetric quantification. The effect of inoculation of bacteria on maize was determined in a completely randomized greenhouse experiment where root and shoot dry weights and phosphorus content were assessed. Results showed that strain C50 produced 107.2 mg .L-1 of available-P after 12 days of fermentation, and AC10 strain had the highest phosphatase activity at pH 8 with 12.7 mg of p-nitrophenol mL .h-1. All strains synthetized indolic compounds, and strain AV5 strain produced the most at 63.03 µg .mL-1. These diazotrophic bacteria increased plant biomass up to 39 % and accumulation of phosphorus by 10%. Hence, use of diazotrphic phosphate-solubilizing bacteria may represent an alternative technology for fertilization systems in maize plants.

  18. Early PCR detection of tyramine-producing bacteria during cheese production.

    Science.gov (United States)

    Fernández, María; Belén Flórez, Ana; Linares, Daniel M; Mayo, Baltasar; Alvarez, Miguel A

    2006-08-01

    Biogenic amines (BA) are toxic substances that appear in foods and beverages. Tyramine is the most abundant BA in cheeses. A PCR method was developed to detect the presence of tyramine-producing bacteria during cheese manufacture and ripening. Six different batches of a farmhouse blue cheese were analysed by PCR. Tyramine concentrations were also determined by HPLC. The PCR method was able to anticipate tyramine accumulation in the cheeses; the presence of tyramine-producing microorganisms in the early stages of manufacture correlated well with a high concentration of BA in mature cheese samples.

  19. Akbu-LAAO exhibits potent anti-tumor activity to HepG2 cells partially through produced H2O2 via TGF-β signal pathway.

    Science.gov (United States)

    Guo, Chunmei; Liu, Shuqing; Dong, Panpan; Zhao, Dongting; Wang, Chengyi; Tao, Zhiwei; Sun, Ming-Zhong

    2015-12-14

    Previously, we characterized the biological properties of Akbu-LAAO, a novel L-amino acid oxidase from Agkistrodon blomhoffii ussurensis snake venom (SV). Current work investigated its in vitro anti-tumor activity and underlying mechanism on HepG2 cells. Akbu-LAAO inhibited HepG2 growth time and dose-dependently with an IC50 of ~38.82 μg/mL. It could induce the apoptosis of HepG2 cells. Akbu-LAAO exhibited cytotoxicity by inhibiting growth and inducing apoptosis of HepG2 as it showed no effect on its cell cycle. The inhibition of Akbu-LAAO to HepG2 growth partially relied on enzymatic-released H2O2 as catalase only partially antagonized this effect. cDNA microarray results indicated TGF-β signaling pathway was linked to the cytotoxicity of Akbu-LAAO on HepG2. TGF-β pathway related molecules CYR61, p53, GDF15, TOB1, BTG2, BMP2, BMP6, SMAD9, JUN, JUNB, LOX, CCND1, CDK6, GADD45A, CDKN1A were deregulated in HepG2 following Akbu-LAAO stimulation. The presence of catalase only slightly restored the mRNA changes induced by Akbu-LAAO for differentially expressed genes. Meanwhile, LDN-193189, a TGF-β pathway inhibitor reduced Akbu-LAAO cytotoxicity on HepG2. Collectively, we reported, for the first time, SV-LAAO showed anti-tumor cell activity via TGF-β pathway. It provides new insight of SV-LAAO exhibiting anti-tumor effect via a novel signaling pathway.

  20. Characterization of some bacteriocins produced by lactic acid bacteria isolated from fermented foods.

    Science.gov (United States)

    Grosu-Tudor, Silvia-Simona; Stancu, Mihaela-Marilena; Pelinescu, Diana; Zamfir, Medana

    2014-09-01

    Lactic acid bacteria (LAB) isolated from different sources (dairy products, fruits, fresh and fermented vegetables, fermented cereals) were screened for antimicrobial activity against other bacteria, including potential pathogens and food spoiling bacteria. Six strains have been shown to produce bacteriocins: Lactococcus lactis 19.3, Lactobacillus plantarum 26.1, Enterococcus durans 41.2, isolated from dairy products and Lactobacillus amylolyticus P40 and P50, and Lactobacillus oris P49, isolated from bors. Among the six bacteriocins, there were both heat stable, low molecular mass polypeptides, with a broad inhibitory spectrum, probably belonging to class II bacteriocins, and heat labile, high molecular mass proteins, with a very narrow inhibitory spectrum, most probably belonging to class III bacteriocins. A synergistic effect of some bacteriocins mixtures was observed. We can conclude that fermented foods are still important sources of new functional LAB. Among the six characterized bacteriocins, there might be some novel compounds with interesting features. Moreover, the bacteriocin-producing strains isolated in our study may find applications as protective cultures.

  1. Molecular Identification of Lactic Acid Bacteria Producing Antimicrobial Agents from Bakasang, An Indonesian Traditional Fermented Fish Product

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    Helen Joan Lawalata

    2015-11-01

    Full Text Available AbstractTwenty seven strains of lactic acid bacteria (LAB were isolated from bakasang, Indonesian traditional fermented fish product. In general, LAB have inhibitory activity againts pathogenic bacteria and spoilage bacteria. Screening for antimicrobia activity of isolates were performed with well-diffusion method. One isolate that was designed as Pediococcus BksC24 was the strongest against bacteria pathogenic and spoilage bacteria. This strain was further identified by 16S rRNA gen sequence comparison. Isolates LAB producing antimicrobial agents from bakasang were identified as Pediococcus acidilactici.Keywords : Bakasang, LAB, antimicrobial, phenotypic characteristics, 16S rRNA gene

  2. Current state of purification, isolation and analysis of bacteriocins produced by lactic acid bacteria.

    Science.gov (United States)

    Kaškonienė, Vilma; Stankevičius, Mantas; Bimbiraitė-Survilienė, Kristina; Naujokaitytė, Gintarė; Šernienė, Loreta; Mulkytė, Kristina; Malakauskas, Mindaugas; Maruška, Audrius

    2017-02-01

    The scientific interest for the search of natural means of microbial inhibitors has not faded for several years. A search of natural antibiotics, so-called bacteriocins which are produced by lactic acid bacteria (LAB), gains a huge attention of the scientists in the last century, in order to reduce the usage of synthetic food additives. Pure bacteriocins with wide spectra of antibacterial activity are promising among the natural biopreservatives. The usage of bacteriocin(s) producing LAB as starter culture for the fermentation of some food products, in order to increase their shelf-life, when synthetic preservatives are not allowable, is also possible. There are a lot of studies focusing on the isolation of new bacteriocins from traditional fermented food, dairy products and other foods or sometimes even from unusual non-food matrices. Bacteriocins producing bacteria have been isolated from different sources with the different antibacterial activity against food-borne microorganisms. This review covers the classification of bacteriocins, diversity of sources of bacteriocin(s) producing LAB, antibacterial spectra of isolated bacteriocins and analytical methods for the bacteriocin purification and analysis within the last 15 years.

  3. Inhibition of Listeria monocytogenes biofilms by bacteriocin-producing bacteria isolated from mushroom substrate.

    Science.gov (United States)

    Bolocan, A S; Pennone, V; O'Connor, P M; Coffey, A; Nicolau, A I; McAuliffe, O; Jordan, K

    2017-01-01

    This study was designed to investigate the ability of naturally occurring bacteria isolated from mushroom substrate to prevent biofilm formation by Listeria monocytogenes or to remove existing biofilms in mushroom production facilities. It is generally recognized that L. monocytogenes forms biofilms that can facilitate its survival in food-processing environments. Eleven bacteriocin-producing isolates were identified and the bacteriocins characterized based on heat and enzyme inactivation studies. Further characterization was undertaken by MALDI-TOF mass spectrometry, PCR and sequencing. Production of nisin Z (by Lactococcus lactis isolates), subtilomycin (by Bacillus subtilis isolates) and lichenicidin (by Bacillus licheniformis and Bacillus sonorensis isolates) was detected. In co-culture with L. monocytogenes, the bacteriocin-producing strains could prevent biofilm formation and reduce pre-formed biofilms. Mushroom substrate can be a source of bacteriocin-producing bacteria that can antagonize L. monocytogenes. The results highlight the potential of bacteriocin-producing strains from mushroom substrate to reduce L. monocytogenes biofilm in food production environments, contributing to a reduction in the risk of food contamination from the environment. © 2016 The Society for Applied Microbiology.

  4. Influence of levan-producing acetic acid bacteria on buckwheat-sourdough breads.

    Science.gov (United States)

    Ua-Arak, Tharalinee; Jakob, Frank; Vogel, Rudi F

    2017-08-01

    Buckwheat sourdoughs supplemented with molasses as natural sucrose source were fermented with levan-producing Gluconobacter (G.) albidus TMW 2.1191 and Kozakia (K.) baliensis NBRC 16680. Cell growth, concomitant levan and low-molecular-weight metabolite production were monitored. Sourdough breads were prepared with different sourdoughs from both strains (24, 30 and 48 h fermentation, respectively) and analyzed with respect to bread volume, crumb hardness and sensory characteristics. During fermentation, levan, acetic and gluconic acids were increasingly produced, while spontaneously co-growing lactic acid bacteria additionally formed acetic and lactic acids. Sourdoughs from both strains obtained upon 24 h of fermentation significantly improved the bread sensory and quality, including higher specific volume as well as lower crumb hardness. Buckwheat doughs containing isolated levan, with similar molecular size and mass compared to in situ produced levan in the sourdough at 48 h, verified the positive effect of levan on bread quality. However, the positive effects of levan were masked to a certain extent by the impact from the natural acidification during fermentations. While levan-producing acetic acid bacteria are a promising alternative for the development of clean-label gluten-free breads without the need of additives, an appropriate balance between acidification and levan production (amount and structure) must be reached. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Yield emulsifiers exopolysaccharides produced by native halophilic bacteria concentrations molasses three Saccharum officinarum L. "sugarcane"

    Directory of Open Access Journals (Sweden)

    Ángel Fuentes, Carmen Carreño

    2013-06-01

    Full Text Available The microbial exopolysaccharide with emulsifying properties are an alternative to polymers and chemicals from algae and plants. Its production in molasses as carbon source lowers costs and generates added value to this byproduct of the sugar industry, so the aim of this study was to determine the performance and productivity of EPS emulsifiers by native halophilic bacteria in 20, 30 and 40 gL-1 of molasses. In MY synthetic medium with 5 % w/v of salts, 138 isolates of bacteria obtained from soil samples of salt water and in the districts of San Jose and Santa Rosa, in Lambayeque. In 10.8 % of these gummy colony forming bacteria and grown on glucose as carbon source EPS recovered whose maximum values of the mixtures in water emulsion - oil phase were 63.3 and 56.6 % after 1 and 24 hours, respectively. The M5 bacteria identified as Halomonas C1 10-1 sp. M5 EPS synthesized emulsifiers molasses broth, reaching yields Yp/s of 0.296 gg-1 and 0.200 gg-1 with 20 and 30 gL-1 of molasses respectively, a productivity of 0.016 and 0.017 gL-1 h -1 , not differing significantly between them. With 10 gL-1 glucose was reached Yp/s of 0.171 gg-1 and a productivity of 0.018 gL-1 h -1 . It was shown that the EPS produced native halophilic bacteria utilizing molasses emulsifiers as carbon source.

  6. Isolation and screening of native polyhydroxyalkanoate producing bacteria from oil contaminated soils of Abadan refinery

    Directory of Open Access Journals (Sweden)

    Hossein MOtamedi

    2015-02-01

    Full Text Available   Introduction : Environmental contaminations due to petrochemical plastic usage have forced researchers to search new biological methods for biodegradable polymer production. The aim of this study was to find native PHA producing bacteria from Abadan oil refinery in order to be used in biodegradable polymer production studies.   Materials and method s : For this purpose soil samples were harvested from oil sludge contaminated soil of Abadan refinery. After primary enrichment, screening of PHA producing bacteria was done by PHA- Detection agar and was confirmed by Sudan black and Nile Blue A staining methods. These isolates were identified based on phenotypic methods and sequencing of 16s rRNA. Polymer extraction was performed and optimized using different concentrations of HClO and SDS.   Results : As a result of this study 26 different bacterial isolates were obtained from which 17 isolates were PHA producer with different potentiality. Based on the polymer accumulation 4 isolates were selected for further studies. The efficiency of PHA production in these isolates was 75.53±5.08, 82±19.05, 81.06±6.92 and 79.86±11.84%. Based on sequence analysis in NCBI database, these isolates were identified as Bacillus cereus.   Discussion and conclusion : With respect to the results of this study it can be suggested that oil contaminated soils due to high C/N and C/P ratios and also different carbohydrate contents are suitable candidates for PHA producer bacteria isolation. So the native strains in such habitats with high carbon content can be optimized for industrial polymer production.

  7. Density Functional Theory and Car-Parrinello Molecular Dynamics Study of the Hydrogen-Producing Mechanism of the Co(dmgBF2)2 and Co(dmgH)2 Cobaloxime Complexes in Acetonitrile-Water Solvent.

    Science.gov (United States)

    Chen, Jinfan; Sit, Patrick H-L

    2017-05-11

    The catalytic hydrogen-producing processes of two prototypical cobaloxime catalysts, Co(dmgBF2)2 (dmgBF2 = difluoroboryl-dimethylglyoxime) and Co(dmgH)2 (dmgH = dimethylglyoxime), were studied by density functional theory (DFT) and Car-Parrinello molecular dynamics (CPMD) simulations in the explicit acetonitrile-water solvent. Our study demonstrates the key role of water molecules as shuttles to deliver protons to the cobalt active centers of these catalysts. However, the transfer of protons to the cobalt centers also competes with the diffusion of the proton away from the complex via the hydrogen bond network of water. Protons were found to react with the oxygen of the side group of Co(dmgH)2, while a similar reaction was not observed for Co(dmgBF2)2. This explains the experimentally observed relative instability of Co(dmgH)2 in the acidic medium. The rate-limiting step of the hydrogen-producing process was found to be the first proton transfer to the cobalt center for both cobaloxime complexes. Structural and electron population analysis was carried out to provide insight into the origin of the difference of the proton transfer free-energy barriers of these two cobalt complexes. Our study has contributed to the key microscopic understanding of the hydrogen-producing process by this class of catalysts.

  8. Genomic and Haplotype Comparison of Butanol Producing Bacteria Based on 16S rDNA

    Directory of Open Access Journals (Sweden)

    Ekwan Nofa Wiratno

    2016-04-01

    Full Text Available High butanol demand for transportation fuel triggers butanol production development. Exploration of butanolproducing bacteria using genomic comparison and biogeography will help to develop butanol industry. The objectives of this research were butanol production, genome comparison and haplotype analysis of butanolproducing bacteria from Ranu Pani Lake sediment using 16S rDNA sequences. The highest butanol concentrations were showed by Paenibacillus polymyxa RP 2.2 isolate (10.34 g.L-1, followed by Bacillus methylotrophicus RP 3.2 and B. methylotrophicus RP 7.2 isolate (10.11 g.L-1 and 9.63 g.L-1 respectively. Paenibacillus polymyxa RP 2.2 showed similarity in nucleotide composition (ATGC with B. methylotrophicus RP 3.2, B. methylotrophicus RP 7.2, P. polymyxa CR1, Bacillus amyloliquefaciens NELB-12, and Paenibacillus polymyxa WR-2. Clostridium acetobutylicum ATCC 824 showed similarity in nucleotide composition (ATGC with Clostridium saccharoperbutylacetonicum N1-4, and Clostridium saccharobutylicum Ox29. The lowest G+C content was C. saccharobutylicum Ox29 (51.35%, and the highest was B. methylotrophicus RP 7.2 (55.33%. Conserved region of 16S rDNA (1044 bp were consisted of 17 conserved sequences. The number of Parsimony Informative Site (PIS was 319 spot and single tone was 48 spot. We found in this study that all of butanolproducing bacterial DNA sequences have clustered to 8 haplotypes. Based on the origin of sample, there were three haplotype groups. Bacteria from group A were could produce butanol 8.9-10.34 g.L-1, group B 9.2-14.2 g.L-1 and group C was could produce butanol 0.47 g.L-1. The haplotype analysis of bacteria based on 16S rDNA sequences in this study could predict capability of butanol production.

  9. ACC deaminase and IAA producing growth promoting bacteria from the rhizosphere soil of tropical rice plants.

    Science.gov (United States)

    Bal, Himadri Bhusan; Das, Subhasis; Dangar, Tushar K; Adhya, Tapan K

    2013-12-01

    Beneficial plant-associated bacteria play a key role in supporting and/or promoting plant growth and health. Plant growth promoting bacteria present in the rhizosphere of crop plants can directly affect plant metabolism or modulate phytohormone production or degradation. We isolated 355 bacteria from the rhizosphere of rice plants grown in the farmers' fields in the coastal rice field soil from five different locations of the Ganjam district of Odisha, India. Six bacteria producing both ACC deaminase (ranging from 603.94 to 1350.02 nmol α-ketobutyrate mg(-1)  h(-1) ) and indole acetic acid (IAA; ranging from 10.54 to 37.65 μM ml(-1) ) in pure cultures were further identified using polyphasic taxonomy including BIOLOG((R)) , FAME analysis and the 16S rRNA gene sequencing. Phylogenetic analyses of the isolates resulted into five major clusters to include members of the genera Bacillus, Microbacterium, Methylophaga, Agromyces, and Paenibacillus. Seed inoculation of rice (cv. Naveen) by the six individual PGPR isolates had a considerable impact on different growth parameters including root elongation that was positively correlated with ACC deaminase activity and IAA production. The cultures also had other plant growth attributes including ammonia production and at least two isolates produced siderophores. Study indicates that presence of diverse rhizobacteria with effective growth-promoting traits, in the rice rhizosphere, may be exploited for a sustainable crop management under field conditions. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Bacterias marinas productoras de compuestos antibacterianos aisladas a partir de invertebrados intermareales Marine bacteria producing antibacterial compounds Isolated from inter-tidal invertebrates

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    Jorge León

    2010-06-01

    Full Text Available Se realizó actividades prospectivas de muestreo de invertebrados intermareales en la Bahía de Ancón (Lima - Perú con el objetivo de seleccionar bacterias marinas productoras de sustancias antimicrobianas. El estudio comprendió el aislamiento de bacterias en agar marino, pruebas de susceptibilidad antimicrobiana in vitro y observaciones de microscopía electrónica. Se reporta el aislamiento, caracterización fenotípica y propiedades antimicrobianas de diez cepas de bacterias marinas que incluyen a los géneros Vibrio, Pseudomonas y Flavobacterium y del orden Actinomycetal que inhiben a patógenos de humanos. Los resultados indicarían que los invertebrados marinos serían fuentes de bacterias productoras de sustancias antibióticas.Prospective sampling activities of intertidal invertebrates in the Ancon Bay (Lima, Peru were done in order to select marine bacteria producing antimicrobial substances. The study included the isolation of bacteria in marine agar, in vitro antimicrobial susceptibility testing and electronic microscopic observations. We report the isolation, phenotypical characterization and antimicrobial properties of 10 strains of marine bacteria including the genus Vibrio, Pseudomonas, and Flavobacterium, and the order Actinomycetae that inhibit human pathogens. The results indicate that the marine invertebrates would be sources of bacteria producing antibiotic substances.

  11. H2 metabolism in the photosynthetic bacterium Rhodopseudomonas capsulata: production and utilization of H2 by resting cells.

    Science.gov (United States)

    Hillmer, P; Gest, H

    1977-02-01

    Photoproduction of H2 and activation of H2 for CO2 reduction (photoreduction) by Rhodopseudomonas capsulata are catalyzed by different enzyme systems. Formation of H2 from organic compounds is mediated by nitrogenase and is nto inhibited by an atmosphere of 99% H2. Cells grown photoheterotrophically on C4 dicarboxylic acids (with glutamate as N source) evolve H2 from the C4 acids and also from lactate and pyruvate; cells grown on C3 carbon sources, however, are inactive with the C4 acids, presumably because they lack inducible transport systems. Ammonia is known to inhibit N2 fixation by photosynthetic bacteria, and it also effectively prevents photoproduction of H2; these effects are due to inhibition and, in part, inactivation of nitrogenase. Biosynthesis of the latter, as measured by both H2 production and acetylene reduction assays, is markedly increased when cells are grown at high light intensity; synthesis of the photoreduction system, on the other hand, is not appreciably influenced by light intensity during photoheterotrophic growth. The photoreduction activity of cells grown on lactate + glutamate (which contain active nitrogenase) is greatly activated by NH4+, but this effect is not observed in cells grown with NH4+ as N source (nitrogenase repressed) or in a Nif- mutant that is unable to produce H2. Lactate, malate, and succinate, which are readily used as growth substrates by R. capsulata and are excellent H donors for photoproduction of H2, abolish photoreduction activity. The physiological significances of this phenomenon and of the reciprocal regulatory effects of NH4+ on H2 production and photoreduction are discussed.

  12. Exercise and Prebiotics Produce Stress Resistance: Converging Impacts on Stress-Protective and Butyrate-Producing Gut Bacteria.

    Science.gov (United States)

    Mika, A; Rumian, N; Loughridge, A B; Fleshner, M

    2016-01-01

    The gut microbial ecosystem can mediate the negative health impacts of stress on the host. Stressor-induced disruptions in microbial ecology (dysbiosis) can lead to maladaptive health effects, while certain probiotic organisms and their metabolites can protect against these negative impacts. Prebiotic diets and exercise are feasible and cost-effective strategies that can increase stress-protective bacteria and produce resistance against the detrimental behavioral and neurobiological impacts of stress. The goal of this review is to describe research demonstrating that both prebiotic diets and exercise produce adaptations in gut ecology and the brain that arm the organism against inescapable stress-induced learned helplessness. The results of this research support the novel hypothesis that some of the stress-protective effects of prebiotics and exercise are due to increases in stress-protective gut microbial species and their metabolites. In addition, new evidence also suggests that prebiotic diet or exercise interventions are most effective if given early in life (juvenile-adolescence) when both the gut microbial ecosystem and the brain are plastic. Based on our new understanding of the mechanistic convergence of these interventions, it is feasible to propose that in adults, both interventions delivered in combination may elevate their efficacy to promote a stress-resistant phenotype. © 2016 Elsevier Inc. All rights reserved.

  13. STUDIES ON MICROBIAL DIVERSITY OF POLYGALACTURONASE PRODUCING BACTERIA FROM THE SOIL OF VEGETABLES MARKET OF PATAN

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    SANJAY PATEL , DIPIKA PANDYA AND S.A. BHATT

    2014-12-01

    Full Text Available ABSTRACT: Present work is carried out to check the study microbial diversity of polygalacturonase producing bacteria from the soil of fruits and vegetables market. Soil which is continuously dumped with waste of fruits and vegetables are rich sources of biopolymer viz, pectin, cellulose and hemicellulose. Presence of such biopolymer selectively promotes the growth of microorganisms which have potential to degrade pectin. In this study more than one hundred and twenty bacterial species are isolated from the soil on the basis of their cell and colony morphology. From these isolates, forty five bacterial species found to produce polygalacturonase enzyme and same have check for capability to produce protease and amylase enzyme. This study provides useful information of the microbial diversity of the soil of fruits and vegetable market. Further it is helpful to study the metabolism of microorganisms to degrade diverse biopolymer.

  14. Isolation of Biosurfactant–Producing Bacteria with Antimicrobial Activity against Bacterial Pathogens

    Directory of Open Access Journals (Sweden)

    Siripun Sarin

    2011-01-01

    Full Text Available The aims of this research were to study biosurfactant producing bacteria isolated from soil and to determine their property and efficiency as biosurfactants in order to inhibit bacterial pathogens. The result showed that there were 8 bacterial isolates out of 136 isolates of the total biosurfactant producing bacteria screened that exhibited the diameter of clear zone more than 1.5 cm. in the oil spreading test. The highest potential of emulsifying activity (%EA24 of 54.4 and the maximum additive concentration, (%MAC of 24.2 was obtained from the fermentation broth of the G7 isolate which the G7 isolate was later identified as Pseudomonas fluorescens. Escherichia coli, Staphylococcus aureus and Psuedomonas aeruginosa were the tested bacterial pathogens that were most sensitive to the acid precipitated biosurfactant obtained from P. fluorescens G7 with the lowest minimum inhibitory concentration (MIC of 41.6 mg/ml and minimum bactericidal concentration (MBC of 41.6 mg/ml compared with the acid precipitated bisurfactants of the other isolates used in the antimicrobial activity test. The type of the separated crude biosurfactant produced by P. fluorescens G7 analyzed later by using the rhamose test, TLC and FT-IR techniques was rhamnolipid.

  15. Isolation and characterization of lactic acid bacteria strains with ornithine producing capacity from natural sea salt.

    Science.gov (United States)

    Yu, Jin-Ju; Oh, Suk-Heung

    2010-08-01

    Two lactic acid bacteria (LAB) having ornithine-producing capacity were isolated from Korean natural sea salt. They were Gram-positive, short rod-type bacteria, and able to grow anaerobically with CO(2) production. The isolates grew well on MRS broth at 30-37 degrees C and a pH of 6.5-8.0. The optimum temperature and pH for growth are 37 degrees C and pH 7.0. The isolates fermented D-ribose, D-galactose, D-lactose, D-maltose, Dcellobiose, D-tagatose, D-trehalose, sucrose, D-melezitose, gentiobiose, D-glucose but not D-melibiose, inositol, and L-sorbose. The 16S rDNA sequences of the two isolates showed 99.5% and 99.6% homology with the Weissella koreensis S5623 16S rDNA (Access no. AY035891). They were accordingly identified and named as Weissella koreensis MS1-3 and Weissella koreensis MS1-14, and produced intracellular ornithine at levels of 72 mg/100 g cell F.W. and 105 mg/100 g cell F.W. and extracellular ornithine at levels of 4.5 mg/100 ml and 4.6 mg/100 ml medium, respectively, by culturing in MRS broth supplemented with 1% arginine. High cell growth was maintained in MRS broth with a NaCl concentration of 0-6%. These results show for the first time that Korean natural sea salts contain lactic acid bacteria Weissella koreensis strains having ornithine producing capacity.

  16. The prospects of cellulase-producing bacteria for the bioconversion of lignocellulosic biomass

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    Miranda Maki, Kam Tin Leung, Wensheng Qin

    2009-01-01

    Full Text Available Lignocellulosic biomass is a renewable and abundant resource with great potential for bioconversion to value-added bioproducts. However, the biorefining process remains economically unfeasible due to a lack of biocatalysts that can overcome costly hurdles such as cooling from high temperature, pumping of oxygen/stirring, and, neutralization from acidic or basic pH. The extreme environmental resistance of bacteria permits screening and isolation of novel cellulases to help overcome these challenges. Rapid, efficient cellulase screening techniques, using cellulase assays and metagenomic libraries, are a must. Rare cellulases with activities on soluble and crystalline cellulose have been isolated from strains of Paenibacillus and Bacillus and shown to have high thermostability and/or activity over a wide pH spectrum. While novel cellulases from strains like Cellulomonas flavigena and Terendinibacter turnerae, produce multifunctional cellulases with broader substrate utilization. These enzymes offer a framework for enhancement of cellulases including: specific activity, thermalstability, or end-product inhibition. In addition, anaerobic bacteria like the clostridia offer potential due to species capable of producing compound multienzyme complexes called cellulosomes. Cellulosomes provide synergy and close proximity of enzymes to substrate, increasing activity towards crystalline cellulose. This has lead to the construction of designer cellulosomes enhanced for specific substrate activity. Furthermore, cellulosome-producing Clostridium thermocellum and its ability to ferment sugars to ethanol; its amenability to co-culture and, recent advances in genetic engineering, offer a promising future in biofuels. The exploitation of bacteria in the search for improved enzymes or strategies provides a means to upgrade feasibility for lignocellulosic biomass conversion, ultimately providing means to a 'greener' technology.

  17. Antibacterial Activity of Selected Standard Strains of Lactic Acid Bacteria Producing Bacteriocins – Pilot Study

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    Malgorzata Bodaszewska-Lubas

    2012-10-01

    Full Text Available  Introduction:In this paper, an attempt was made to evaluate the antibacterial potential of standard strains of lactic acid bacteria (LAB producing bacteriocins of various classes, thus demonstrating various mechanisms of cell membrane damages against the Streptococcus agalactiae strains (Group B Streptococcus, GBS, depending on surface polysaccharides and surface alpha-like protein genes.Materials/Methods:Antimicrobial property of the strains of L. plantarum C 11, L. sakei DSMZ 6333, and L. lactis ATCC 11454 producing bacteriocins: JK and EF plantaricins, sakacin and nisin, respectively, against the GBS strains was evaluated. The chosen to the study GBS strains were represented by serotypes Ia, Ib, II, III, V and they had bca, epsilon, rib, alp2 or alp3 alpha-like protein genes. The experiment was conducted by means of suspension culture and the bacteria count was determined using the serial dilution method.Results:A great ability of L. plantarum C 11 strain was proven to inhibit the GBS growth. The strain of L. sakei DSMZ 6333 did not demonstrate any ability to inhibit the growth of GBS, whereas L. lactis ATCC 11454 inhibited the growth of S. agalactiae indicator strains to a minor extent. Statistically significant differences were demonstrated between the GBS strains representing various serotypes against the antimicrobial activity of model LAB strains. The least sensitive to the activity of bacteriocins were the strains representing serotypes Ib and III, whereas the strains representing serotype II were the most sensitive. The sensitivity of the GBS strains to the antimicrobial activity of LAB was not dependent on alpha-like protein genes.Discussion:Among the LAB standard strains producing bacteriocins, the strongest antimicrobial property was observed in the strain of L. plantarum C 11. Because of the generally known and verified strong antagonistic property of the strains of L. plantarum species against indicator bacteria, it is necessary

  18. N-acyl-homoserine lactones-producing bacteria protect plants against plant and human pathogens.

    Science.gov (United States)

    Hernández-Reyes, Casandra; Schenk, Sebastian T; Neumann, Christina; Kogel, Karl-Heinz; Schikora, Adam

    2014-11-01

    The implementation of beneficial microorganisms for plant protection has a long history. Many rhizobia bacteria are able to influence the immune system of host plants by inducing resistance towards pathogenic microorganisms. In this report, we present a translational approach in which we demonstrate the resistance-inducing effect of Ensifer meliloti (Sinorhizobium meliloti) on crop plants that have a significant impact on the worldwide economy and on human nutrition. Ensifer meliloti is usually associated with root nodulation in legumes and nitrogen fixation. Here, we suggest that the ability of S. meliloti to induce resistance depends on the production of the quorum-sensing molecule, oxo-C14-HSL. The capacity to enhanced resistance provides a possibility to the use these beneficial bacteria in agriculture. Using the Arabidopsis-Salmonella model, we also demonstrate that the application of N-acyl-homoserine lactones-producing bacteria could be a successful strategy to prevent plant-originated infections with human pathogens. © 2014 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  19. Structural and rheological characterisation of heteropolysaccharides produced by lactic acid bacteria in wheat and sorghum sourdough.

    Science.gov (United States)

    Galle, Sandra; Schwab, Clarissa; Arendt, Elke K; Gänzle, Michael G

    2011-05-01

    Hydrocolloids improve the volume, texture, and shelf life of bread. Exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) during sourdough fermentation can replace hydrocolloids. It was the aim of this study to determine whether heteropolysaccharides (HePS) synthesized intracellularly from sugar nucleotides by glycosyltransferases are produced in wheat and gluten-free sorghum sourdough at effective levels. The HePS-producing strains Lactobacillus casei FUA3185, L. casei FUA3186, and Lactobacillus buchneri FUA3154 were used; Weissella cibaria 10M producing no EPS in the absence of sucrose served as control strain. Cell suspensions of L. buchneri in MRS showed the highest viscosity at low shear rate. Glycosyltransferase genes responsible of HePS formation in LAB were expressed in sorghum and wheat sourdough. However, only HePS produced by L. buchneri influenced the rheological properties of sorghum sourdoughs but not of wheat sourdoughs. Sorghum sourdough fermented with L. buchneri exhibited a low |G*| compared to the control, indicating a decrease in resistance to deformation. An increase in tan δ indicated decreased elasticity. The use of LAB producing HePS expands the diversity of EPS and increases the variety of cultures for use in baking.

  20. Distribution of biosurfactant-producing bacteria in undisturbed and contaminated arid Southwestern soils.

    Science.gov (United States)

    Bodour, Adria A; Drees, Kevin P; Maier, Raina M

    2003-06-01

    Biosurfactants are a unique class of compounds that have been shown to have a variety of potential applications in the remediation of organic- and metal-contaminated sites, in the enhanced transport of bacteria, in enhanced oil recovery, as cosmetic additives, and in biological control. However, little is known about the distribution of biosurfactant-producing bacteria in the environment. The goal of this study was to determine how common culturable surfactant-producing bacteria are in undisturbed and contaminated sites. A series of 20 contaminated (i.e., with metals and/or hydrocarbons) and undisturbed soils were collected and plated on R(2)A agar. The 1,305 colonies obtained were screened for biosurfactant production in mineral salts medium containing 2% glucose. Forty-five of the isolates were positive for biosurfactant production, representing most of the soils tested. The 45 isolates were grouped by using repetitive extragenic palindromic (REP)-PCR analysis, which yielded 16 unique isolates. Phylogenetic relationships were determined by comparing the 16S rRNA gene sequence of each unique isolate with known sequences, revealing one new biosurfactant-producing microbe, a Flavobacterium sp. Sequencing results indicated only 10 unique isolates (in comparison to the REP analysis, which indicated 16 unique isolates). Surface tension results demonstrated that isolates that were similar according to sequence analysis but unique according to REP analysis in fact produced different surfactant mixtures under identical growth conditions. These results suggest that the 16S rRNA gene database commonly used for determining phylogenetic relationships may miss diversity in microbial products (e.g., biosurfactants and antibiotics) that are made by closely related isolates. In summary, biosurfactant-producing microorganisms were found in most soils even by using a relatively limited screening assay. Distribution was dependent on soil conditions, with gram-positive biosurfactant-producing

  1. Exopolysaccharides produced by the symbiotic nitrogen-fixing bacteria of leguminosae

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    Cleide Aparecida Bomfeti

    2011-06-01

    Full Text Available The process of biological nitrogen fixation (BNF, performed by symbiotic nitrogen fixing bacteria with legume species, commonly known as α and β rhizobia, provides high sustainability for the ecosystems. Its management as a biotechnology is well succeeded for improving crop yields. A remarkable example of this success is the inoculation of Brazilian soybeans with Bradyrhizobium strains. Rhizobia produce a wide diversity of chemical structures of exopolysaccharides (EPS. Although the role of EPS is relatively well studied in the process of BNF, their economic and environmental potential is not yet explored. These EPS are mostly species-specific heteropolysaccharides, which can vary according to the composition of sugars, their linkages in a single subunit, the repeating unit size and the degree of polymerization. Studies have showed that the EPS produced by rhizobia play an important role in the invasion process, infection threads formation, bacteroid and nodule development and plant defense response. These EPS also confer protection to these bacteria when exposed to environmental stresses. In general, strains of rhizobia that produce greater amounts of EPS are more tolerant to adverse conditions when compared with strains that produce less. Moreover, it is known that the EPS produced by microorganisms are widely used in various industrial activities. These compounds, also called biopolymers, provide a valid alternative for the commonly used in food industry through the development of products with identical properties or with better rheological characteristics, which can be used for new applications. The microbial EPS are also able to increase the adhesion of soil particles favoring the mechanical stability of aggregates, increasing levels of water retention and air flows in this environment. Due to the importance of EPS, in this review we discuss the role of these compounds in the process of BNF, in the adaptation of rhizobia to environmental

  2. Varying occurrence of extended-spectrum beta-lactamase bacteria among three produce types

    KAUST Repository

    Toh, Benjamin E. W.

    2017-07-07

    A monitoring effort that spanned across 1.5 years was conducted to examine three types of produce-associated microbiota. The average amount of antibiotic-resistant bacteria recovered from lettuce, tomato, and cucumber was 1.02 × 1010, 2.05 × 107, and 4.78 × 109 cells per 50 g of each produce, respectively. A total of 480 bacterial isolates were obtained and identified from their 16S rRNA genes, revealing isolates that were ubiquitously recovered from all three types of produce. However, sporadic presence of Klebsiella pneumoniae and Acinetobacter baumannii was detected on lettuce and cucumbers but not tomatoes. End-point PCR revealed that the K. pneumoniae and A. baumannii isolates were positive for genes encoding extended spectrum beta-lactamase. Whole genome sequencing of two of the K. pneumoniae isolates further suggested the presence of the blaCTX-M-15 gene in a conjugative plasmid, as well as other antibiotic resistance genes and virulence-associated traits in either conjugative plasmids or the chromosomal genome. Quantitative microbial risk assessment indicated varying levels of ingestion risk associated with different types of produce. In particular, the risk arising from ESBL-positive K. pneumoniae in lettuce, but not in cucumbers or tomatoes, was higher than the acceptable annual risk of 10−4. Practical applications Three types of vegetables were sampled and evaluated over 1.5 years to determine differences in their associated bacterial isolates. Particular emphasis was placed on identifying pathogenic strains that were positive for extended spectrum beta-lactamase (ESBL). Quantitative estimates of the microbial risk associated with the ESBL-positive pathogens showed that different produce types may incur varying levels of ingestion risk. Most of the currently reported ESBL-positive bacterial isolates have been identified in nosocomial environments. However, the carriage of such drug-resistant bacteria in vegetables suggests a possible connection

  3. Novel Sorption Enhanced Reaction Process for Simultaneous Production of CO2 and H2 from Synthesis Gas Produced by Coal Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Shivaji Sircar; Hugo S. Caram; Kwangkook Jeong; Michael G. Beaver; Fan Ni; Agbor Tabi Makebe

    2010-06-04

    The goal of this project is to evaluate the extensive feasibility of a novel concept called Thermal Swing Sorption Enhanced Reaction (TSSER) process to simultaneously produce H{sub 2} and CO{sub 2} as a single unit operation in a sorber-reactor. The successful demonstration of the potential feasibility of the TSSER concept implies that it is worth pursuing further development of the idea. This can be done by more extensive evaluation of the basic sorptive properties of the CO{sub 2} chemisorbents at realistic high pressures and by continuing the experimental and theoretical study of the TSSER process. This will allow us to substantiate the assumptions made during the preliminary design and evaluation of the process and firm up the initial conclusions. The task performed under this project consists of (i) retrofitting an existing single column sorption apparatus for measurement of high pressure CO{sub 2} sorption characteristics, (ii) measurement of high pressure CO{sub 2} chemisorption equilibria, kinetics and sorption-desorption column dynamic characteristics under the conditions of thermal swing operation of the TSSER process, (iii) experimental evaluation of the individual steps of the TSSER process (iv) development of extended mathematical model for simulating cyclic continuous operation of TSSER to aid in process scale-up and for guiding future work, (v) simulate and test SER concept using realistic syngas composition, (vi) extensive demonstration of the thermal stability of sorbents using a TGA apparatus, (vii) investigation of the surfaces of the adsorbents and adsorbed CO{sub 2} ,and (viii) test the effects of sulfur compounds found in syngas on the CO{sub 2} sorbents.

  4. Palladium nanoparticles produced by fermentatively cultivated bacteria as catalyst for diatrizoate removal with biogenic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Hennebel, T.; Fitts, J.; Nevel, S. V.; Verschuere, S.; De Corte, S.; De Gusseme, B.; Cuvelier, C.; van der Lelie, D.; Boon, N.; Verstraete, W.

    2011-05-17

    A new biological inspired method to produce nanopalladium is the precipitation of Pd on a bacterium, i.e., bio-Pd. This bio-Pd can be applied as catalyst in dehalogenation reactions. However, large amounts of hydrogen are required as electron donor in these reactions resulting in considerable costs. This study demonstrates how bacteria, cultivated under fermentative conditions, can be used to reductively precipitate bio-Pd catalysts and generate the electron donor hydrogen. In this way, one could avoid the costs coupled to hydrogen supply. The catalytic activities of Pd(0) nanoparticles produced by different strains of bacteria (bio-Pd) cultivated under fermentative conditions were compared in terms of their ability to dehalogenate the recalcitrant aqueous pollutants diatrizoate and trichloroethylene. While all of the fermentative bio-Pd preparations followed first order kinetics in the dehalogenation of diatrizoate, the catalytic activity differed systematically according to hydrogen production and starting Pd(II) concentration in solution. Batch reactors with nanoparticles formed by Citrobacter braakii showed the highest diatrizoate dehalogenation activity with first order constants of 0.45 {+-} 0.02 h{sup -1} and 5.58 {+-} 0.6 h{sup -1} in batches with initial concentrations of 10 and 50 mg L{sup -1} Pd, respectively. Nanoparticles on C. braakii, used in a membrane bioreactor treating influent containing 20 mg L{sup -1} diatrizoate, were capable of dehalogenating 22 mg diatrizoate mg{sup -1} Pd over a period of 19 days before bio-Pd catalytic activity was exhausted. This study demonstrates the possibility to use the combination of Pd(II), a carbon source and bacteria under fermentative conditions for the abatement of environmental halogenated contaminants.

  5. Flow cytometric viability assessment of lactic acid bacteria starter cultures produced by fluidized bed drying.

    Science.gov (United States)

    Bensch, Gerald; Rüger, Marc; Wassermann, Magdalena; Weinholz, Susann; Reichl, Udo; Cordes, Christiana

    2014-06-01

    For starter culture production, fluidized bed drying is an efficient and cost-effective alternative to the most frequently used freeze drying method. However, fluidized bed drying also poses damaging or lethal stress to bacteria. Therefore, investigation of impact of process variables and conditions on viability of starter cultures produced by fluidized bed drying is of major interest. Viability of bacteria is most frequently assessed by plate counting. While reproductive growth of cells can be characterized by the number of colony-forming units, it cannot provide the number of viable-but-nonculturable cells. However, in starter cultures, these cells still contribute to the fermentation during food production. In this study, flow cytometry was applied to assess viability of Lactobacillus plantarum starter cultures by membrane integrity analysis using SYBR®Green I and propidium iodide staining. The enumeration method established allowed for rapid, precise and sensitive determination of viable cell concentration, and was used to investigate effects of fluidized bed drying and storage on viability of L. plantarum. Drying caused substantial membrane damage on cells, most likely due to dehydration and oxidative stress. Nevertheless, high bacterial survival rates were obtained, and granulates contained in the average 2.7 × 10(9) viable cells/g. Furthermore, increased temperatures reduced viability of bacteria during storage. Differences in results of flow cytometry and plate counting suggested an occurrence of viable-but-nonculturable cells during storage. Overall, flow cytometric viability assessment is highly feasible for rapid routine in-process control in production of L. plantarum starter cultures, produced by fluidized bed drying.

  6. Thermophilic hydrogen-producing bacteria inhabiting deep-sea hydrothermal environments represented by Caloranaerobacter.

    Science.gov (United States)

    Jiang, Lijing; Xu, Hongxiu; Zeng, Xiang; Wu, Xiaobing; Long, Minnan; Shao, Zongze

    2015-11-01

    Hydrogen is an important energy source for deep-sea hydrothermal vent ecosystems. However, little is known about microbes and their role in hydrogen turnover in the environment. In this study, the diversity and physiological characteristics of fermentative hydrogen-producing microbes from deep-sea hydrothermal vent fields were described for the first time. Seven enrichments were obtained from hydrothermal vent sulfides collected from the Southwest Indian Ocean, East Pacific and South Atlantic. 16S rRNA gene analysis revealed that members of the Caloranaerobacter genus were the dominant component in these enrichments. Subsequently, three thermophilic hydrogen producers, strains H363, H53214 and DY22619, were isolated. They were phylogenetically related to species of the genus Caloranaerobacter. The H2 yields of strains H363, H53214, DY22619 and MV107, which was the type species of genus Caloranaerobacter, were 0.11, 1.21, 3.13 and 2.85 mol H2/mol glucose, respectively. Determination of the main soluble metabolites revealed that strains H363, H53214 and MV107 performed heterolactic fermentations, while strain DY22619 performed butyric acid fermentation, indicating distinct fermentation patterns among members of the genus. Finally, a diversity of forms of [FeFe]-hydrogenase with different modular structures was revealed based on draft genomic data of Caloranaerobacter strains. This highlights the complexity of hydrogen metabolism in Caloranaerobacter, reflecting adaptations to environmental conditions in hydrothermal vent systems. Collectively, results suggested that Caloranaerobacter species might be ubiquitous and play a role in biological hydrogen generation in deep-sea hydrothermal vent fields.

  7. Prevalence and Characterization of High Histamine-Producing Bacteria in Gulf of Mexico Fish Species.

    Science.gov (United States)

    Bjornsdottir-Butler, Kristin; Bowers, John C; Benner, Ronald A

    2015-07-01

    Recent developments in detection and enumeration of histamine-producing bacteria (HPB) have created powerful molecular-based tools to better understand the presence of spoilage bacteria and conditions, resulting in increased risk of scombrotoxin fish poisoning. We examined 235 scombrotoxin-forming fish from the Gulf of Mexico for the presence of high HPB. Photobacterium damselae subsp. damselae was the most prevalent HPB (49%), followed by Morganella morganii (14%), Enterobacter aerogenes (4%), and Raoultella planticola (3%). The growth characteristics and histamine production capabilities of the two most prevalent HPB were further examined. M. morganii and P. damselae had optimum growth at 35°C and 30 to 35°C and 0 to 2% and 1 to 3% NaCl, respectively. P. damselae produced significantly (P production was not significantly different between the two HPB in inoculated tuna, possibly due to differences in muscle composition and salt content. Results in this study showed that P. damselae was the most prevalent high HPB in Gulf of Mexico fish. In addition, previously reported results using the traditional Niven's method may underreport the prevalence of P. damselae. Molecular-based methods should be used in addition to culture-based methods to enhance detection and enumeration of HPB.

  8. Control of Histamine-Producing Bacteria and Histamine Formation in Fish Muscle by Trisodium Phosphate.

    Science.gov (United States)

    Bjornsdottir-Butler, Kristin; Green, David P; Bolton, Greg E; McClellan-Green, Patricia D

    2015-06-01

    Scombrotoxin fish poisoning remains the primary cause of seafood poisoning outbreaks despite preventive guidelines. The purpose of this study was to investigate the use of pH for the control of growth and histamine formation by histamine-producing bacteria in fish muscle. We examined pH effects on growth and histamine formation in tuna fish infusion broth and in inoculated tuna and mahi-mahi fish muscle. Histamine production was significantly less for all bacterial strains at pH 8.5 compared to pH 5.5 in tuna fish infusion broth with no significant difference in growth. Elevated pH due to phosphate treatment of fish muscle tissues significantly reduced histamine formation with no effect on the growth of histamine-producing bacteria. This study revealed that phosphate treatment of mahi-mahi and tuna fish muscle resulted in significantly lower histamine production over 4 d of storage at 10 °C. Phosphate treatment of fish muscle may serve as a secondary barrier in addition to FDA recommended time and temperature controls for reducing public health concerns of scombrotoxin fish poisoning.

  9. Microbiology of mandibular third molar pericoronitis: incidence of beta-lactamase-producing bacteria.

    Science.gov (United States)

    Sixou, Jean-Louis; Magaud, Christophe; Jolivet-Gougeon, Anne; Cormier, Michel; Bonnaure-Mallet, Martine

    2003-06-01

    The purpose of this study was to evaluate the predominant flora associated with pericoronitis in third molars and to investigate the presence of beta-lactamase-producing strains. The third molars in 26 adults were evaluated by cultures with nonselective media and with selective media containing amoxicillin, pristinamycin, spiramycin, metronidazole, and spiramycin plus metronidazole. In the majority of cases (19/26), the flora found in an anaerobic atmosphere predominated. Obligate anaerobes were present in 21 of the 26 samples. The bacteria most commonly detected were alpha-hemolytic streptococci (26/26) and the genera Prevotella (15/26), Veillonella (15/26), Bacteroides (9/26), and Capnocytophaga (9/26). Amoxicillin and pristinamycin were the most active in reducing the anaerobic cultivable counts. beta-Lactamase-producing strains were detected in 9 samples and were mostly bacteria of the genera Prevotella, Staphylococcus, and Bacteroides. These results highlight (1) the diversity of the microflora associated with pericoronitis and the importance of the anaerobic flora and (2) the existence of selection pressure related to the use of beta-lactams that may culminate in failure of prescribed penicillins.

  10. Exopolysaccharides produced by marine bacteria and their applications as glycosaminoglycan-like molecules.

    Science.gov (United States)

    Delbarre-Ladrat, Christine; Sinquin, Corinne; Lebellenger, Lou; Zykwinska, Agata; Colliec-Jouault, Sylvia

    2014-10-01

    Although polysaccharides are ubiquitous and the most abundant renewable bio-components, their studies, covered by the glycochemistry and glycobiology fields, remain a challenge due to their high molecular diversity and complexity. Polysaccharides are industrially used in food products; human therapeutics fall into a more recent research field and pharmaceutical industry is looking for more and more molecules with enhanced activities. Glycosaminoglycans (GAGs) found in animal tissues play a critical role in cellular physiological and pathological processes as they bind many cellular components. Therefore, they present a great potential for the design and preparation of therapeutic drugs. On the other hand, microorganisms producing exopolysaccharides (EPS) are renewable resources meeting well the actual industrial demand. In particular, the diversity of marine microorganisms is still largely unexplored offering great opportunities to discover high value products such as new molecules and biocatalysts. EPS-producing bacteria from the marine environment will be reviewed with a focus on marine-derived EPS from bacteria isolated from deep-sea hydrothermal vents. Information on chemical and structural features, putative pathways of biosynthesis, novel strategies for chemical and enzymatic modifications and potentialities in the biomedical field will be provided. An integrated approach should be used to increase the basic knowledge on these compounds and their applications; new clean environmentally friendly processes for the production of carbohydrate bio-active compounds should also be proposed for a sustainable industry.

  11. Lactic acid bacteria producing B-group vitamins: a great potential for functional cereals products.

    Science.gov (United States)

    Capozzi, Vittorio; Russo, Pasquale; Dueñas, María Teresa; López, Paloma; Spano, Giuseppe

    2012-12-01

    Wheat contains various essential nutrients including the B group of vitamins. However, B group vitamins, normally present in cereals-derived products, are easily removed or destroyed during milling, food processing or cooking. Lactic acid bacteria (LAB) are widely used as starter cultures for the fermentation of a large variety of foods and can improve the safety, shelf life, nutritional value, flavor and overall quality of the fermented products. In this regard, the identification and application of strains delivering health-promoting compounds is a fascinating field. Besides their key role in food fermentations, several LAB found in the gastrointestinal tract of humans and animals are commercially used as probiotics and possess generally recognized as safe status. LAB are usually auxotrophic for several vitamins although certain strains of LAB have the capability to synthesize water-soluble vitamins such as those included in the B group. In recent years, a number of biotechnological processes have been explored to perform a more economical and sustainable vitamin production than that obtained via chemical synthesis. This review article will briefly report the current knowledge on lactic acid bacteria synthesis of vitamins B2, B11 and B12 and the potential strategies to increase B-group vitamin content in cereals-based products, where vitamins-producing LAB have been leading to the elaboration of novel fermented functional foods. In addition, the use of genetic strategies to increase vitamin production or to create novel vitamin-producing strains will be also discussed.

  12. Exopolysaccharides produced by marine bacteria and their applications as glycosaminoglycan-like molecules.

    Directory of Open Access Journals (Sweden)

    Christine eDELBARRE-LADRAT

    2014-10-01

    Full Text Available Although polysaccharides are ubiquitous and the most abundant renewable bio-components, their studies, covered by the glycochemistry and glycobiology fields, remain a challenge due to their high molecular diversity and complexity.Polysaccharides are industrially used in food products; human therapeutics fall into a more recent research field and pharmaceutical industry is looking for more and more molecules with enhanced activities. Glycosaminoglycans (GAGs found in animal tissues play a critical role in cellular physiological and pathological processes as they bind many cellular components. Therefore, they present a great potential for the design and preparation of therapeutic drugs.On the other hand, microorganisms producing exopolysaccharides (EPS are renewable resources meeting well the actual industrial demand. In particular, the diversity of marine microorganisms is still largely unexplored offering great opportunities to discover high value products such as new molecules and biocatalysts.EPS-producing bacteria from the marine environment will be reviewed with a focus on marine-derived EPS from bacteria isolated from deep-sea hydrothermal vents. Information on chemical and structural features, putative pathways of biosynthesis, novel strategies for chemical and enzymatic modifications and potentialities in the biomedical field will be provided. An integrated approach should be used to increase the basic knowledge on these compounds and their applications; new clean environmentally friendly processes for the production of carbohydrate bio-active compounds should also be proposed for a sustainable industry.

  13. Isolation of palm oil-utilising, polyhydroxyalkanoate (PHA)-producing bacteria by an enrichment technique.

    Science.gov (United States)

    Alias, Zazali; Tan, Irene K P

    2005-07-01

    In early attempts to isolate palm oil-utilising bacteria from palm oil mill effluent (POME), diluted liquid samples of POME were spread on agar containing POME as primary nutrient. 45 purified colonies were screened for intracellular lipids by staining with Sudan Black B. Of these, 10 isolates were positively stained. The latter were grown in a nitrogen-limiting medium with palm olein (a triglyceride) or saponified palm olein (salts of fatty acids) as carbon source. None of the isolates grew in the palm olein medium but all grew well in the saponified palm olein medium. Of the latter however, only one isolate was positively stained with Nile Blue A, indicating the presence of PHA. This method did not successfully generate bacterial isolates which could metabolise palm olein to produce PHA. An enrichment technique was therefore developed whereby a selective medium was designed. The latter comprised minerals and palm olein (1% w/v) as sole carbon source to which POME (2.5% v/v) was added as the source of bacteria. The culture was incubated with shaking at 30 degrees C for 4 weeks. Out of seven isolates obtained from the selective medium, two isolates, FLP1 and FLP2, could utilise palm olein for growth and production of the homopolyester, poly(3-hydroxybutyrate). FLP1 is gram-negative and is identified (BIOLOG) to have 80% similarity to Burkholderia cepacia. When grown with propionate or valerate, FLP1 produced a copolyester, poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

  14. Isolation of biosurfactant-producing marine bacteria and characteristics of selected biosurfactant

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    Kulnaree Phetrong

    2007-05-01

    Full Text Available Biosurfactant-producing marine bacteria were isolated from oil-spilled seawater collected from harbors and docks in Songkhla Province, Thailand. Haemolytic activity, emulsification activity toward nhexadecane,emulsion of weathered crude oil, drop collapsing test as well as oil displacement test were used to determine biosurfactant producing activity of marine bacteria. Among two-hundred different strains, 40strains exhibited clear zone on blood agar plates. Only eight strains had haemolytic activity and were able to emulsify weathered crude oil in marine broth during cultivation. Eight strains named SM1-SM8 wereidentified by 16S rRNA as Myroides sp. (SM1; Vibrio paraheamolyticus (SM2; Bacillus subtilis (SM3; Micrococcus luteus (SM4; Acinetobacter anitratus (SM6; Vibrio paraheamolyticus (SM7 and Bacilluspumilus (SM8. However, SM5 could not be identified. Strain SM1 showed the highest emulsification activity against weathered crude oil, by which the oil was emulsified within 24 h of cultivation. In addition, strainSM1 exhibited the highest activity for oil displacement test and emulsification test toward n-hexadecane. The emulsification activity against n-hexadecane of crude extract of strain SM1 was stable over a broadrange of temperature (30-121oC, pH (5-12 and salt concentration (0-9% NaCl, whereas CaCl2 showed an adverse effect on emulsifying activity.

  15. Supporting data for identification of biosurfactant-producing bacteria isolated from agro-food industrial effluent

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    Mohamad Ali Fulazzaky

    2016-06-01

    Full Text Available The goal of this study was to identify the biosurfactant-producing bacteria isolated from agro-food industrial effluet. The identification of the potential bacterial strain using a polymerase chain reaction of the 16S rRNA gene analysis was closely related to Serratia marcescens with its recorded strain of SA30 “Fundamentals of mass transfer and kinetics for biosorption of oil and grease from agro-food industrial effluent by Serratia marcescens SA30” (Fulazzaky et al., 2015 [1]; however, many biochemical tests have not been published yet. The biochemical tests of biosurfactant production, haemolytic assay and cell surface hydrophobicity were performed to investigate the beneficial strain of biosurfactant-producing bacteria. Here we do share data collected from the biochemical tests to get a better understanding of the use of Serratia marcescens SA30 to degrade oil, which contributes the technical features of strengthening the biological treatment of oil-contaminated wastewater in tropical environments.

  16. Physico-chemical properties of polyhydroxyalkanoate produced by mixed-culture nitrogen-fixing bacteria.

    Science.gov (United States)

    Patel, Meeta; Gapes, Daniel J; Newman, Roger H; Dare, Peter H

    2009-03-01

    Ultra-high molecular weight polyhydroxyalkanoates (PHAs) with low polydispersity index (PDI = 1.3) were produced in a novel, pilot scale application of mixed cultures of nitrogen-fixing bacteria. The number average molecular weight (M (n)) of the poly(3-hydroxybutyrate) (P(3HB)) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) was determined to be 2.4 x 10(6) and 2.5 x 10(6) g mol(-1), respectively. Using two types of carbon sources, biomass contents of the P(3HB) and P(3HB-co-3HV) were 18% and 30% (PHA in dry biomass), respectively. The extracted polymers were analysed for their physical properties using analytical techniques such as nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). NMR confirmed the formation of homopolymer and copolymer. DSC showed a single melting endotherm peak for both polymers, with enthalpies that indicated crystallinity indices of 44% and 37% for P(3HB) and P(3HB-co-3HV), respectively. GPC showed a sharp unimodal trace for both polymers, reflecting the homogeneity of the polymer chains. The work described here emphasises the potential of mixed colony nitrogen-fixing bacteria cultures for producing biodegradable polymers which have properties that are very similar to those from their pure-culture counterparts and therefore making a more economically viable route for obtaining biopolyesters.

  17. Biofilm-forming capacity in biogenic amine-producing bacteria isolated from dairy products.

    Directory of Open Access Journals (Sweden)

    Maria eDiaz

    2016-05-01

    Full Text Available Biofilms on the surface of food industry equipment are reservoirs of potentially food-contaminating bacteria - both spoilage and pathogenic. However, the capacity of biogenic amine (BA-producers to form biofilms has remained largely unexamined. BAs are low molecular weight, biologically active compounds that in food can reach concentrations high enough to be a toxicological hazard. Fermented foods, especially some types of cheese, accumulate the highest BA concentrations of all. The present work examines the biofilm-forming capacity of 56 BA-producing strains belonging to three genera and 10 species (12 Enterococcus faecalis, 6 Enterococcus faecium, 6 Enterococcus durans, 1 Enterococcus hirae, 12 Lactococcus lactis, 7 Lactobacillus vaginalis, 2 Lactobacillus curvatus, 2 Lactobacillus brevis, 1 Lactobacillus reuteri and 7 Lactobacillus parabuchneri, all isolated from dairy products. Strains of all the tested species - except for L. vaginalis - were able to produce biofilms on polystyrene and adhered to stainless steel. However, the biomass produced in biofilms was strain-dependent. These results suggest that biofilms may provide a route via which fermented foods can become contaminated by BA-producing microorganisms.

  18. Extended-spectrum beta-lactamase-producing bacteria are not detected in supragingival plaque samples from human fecal carriers of ESBL-producing Enterobacteriaceae

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    Arne Søraas

    2014-08-01

    Full Text Available Background: The prevalence of infections caused by Cefotaximase-Munich (CTX-M-type extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E has rapidly increased during the past 15 years. Enterobacteriaceae are commonly found in the gastrointestinal tract and long-term intestinal carriage is considered important for the spread of ESBL and as a source of clinical infections. Oral biofilm such as supragingival plaque is known to contain numerous antibiotic resistance determinants and may also represent a poorly investigated site for ESBL carriage and further spread. Objective: To investigate possible carriage of ESBL-producing bacteria in supragingival plaque of known fecal carriers of these bacteria. Design: We screened for the presence of aerobic and anaerobic ESBL-producing bacteria and blaCTX-M in supragingival plaque samples from healthy human adults with culture-verified fecal carriage of CTX-M-producing Escherichia coli. The presence or absence of Enterobacteriaceae and ESBL-producing bacteria in plaque samples was evaluated using culture-based methods and consensus CTX-M PCR. Results: Oral samples were obtained from 17 participants with known previous carriage of ESBL-producing E. coli. No ESBL-producing bacteria or ESBL genes were detected using culture-based and molecular methods. One colony of Rahnella aquatilis harboring the class A ESBL gene bla RAHN-1/2 was identified in an oral sample from one of the participants. Conclusion: This pilot study supports the notion that the presence of CTX-M-producing bacteria is uncommon in oral plaque of healthy human adult fecal carriers. Due to the limited number of persons tested, a low prevalence of oral ESBL-carriage in healthy adults or carriage in selected groups of patients cannot be excluded. To our knowledge, this is the first description of an R. aquatilis with the RAHN-1/2 gene in the oral cavity.

  19. Exopolysaccharides produced by lactic acid bacteria: from health-promoting benefits to stress tolerance mechanisms.

    Science.gov (United States)

    Caggianiello, Graziano; Kleerebezem, Michiel; Spano, Giuseppe

    2016-05-01

    A wide range of lactic acid bacteria (LAB) is able to produce capsular or extracellular polysaccharides, with various chemical compositions and properties. Polysaccharides produced by LAB alter the rheological properties of the matrix in which they are dispersed, leading to typically viscous and "ropy" products. Polysaccharides are involved in several mechanisms such as prebiosis and probiosis, tolerance to stress associated to food process, and technological properties of food. In this paper, we summarize the beneficial properties of exopolysaccharides (EPS) produced by LAB with particular attention to prebiotic properties and to the effect of exopolysaccharides on the LAB-host interaction mechanisms, such as bacterial tolerance to gastrointestinal tract conditions, ability of ESP-producing probiotics to adhere to intestinal epithelium, their immune-modulatory activity, and their role in biofilm formation. The pro-technological aspect of exopolysaccharides is discussed, focusing on advantageous applications of EPS in the food industry, i.e., yogurt and gluten-free bakery products, since it was found that these microbial biopolymers positively affect the texture of foods. Finally, the involvement of EPS in tolerance to stress conditions that are commonly encountered in fermented beverages such as wine is discussed.

  20. Selection and characterization of biofuel-producing environmental bacteria isolated from vegetable oil-rich wastes.

    Directory of Open Access Journals (Sweden)

    Almudena Escobar-Niño

    Full Text Available Fossil fuels are consumed so rapidly that it is expected that the planet resources will be soon exhausted. Therefore, it is imperative to develop alternative and inexpensive new technologies to produce sustainable fuels, for example biodiesel. In addition to hydrolytic and esterification reactions, lipases are capable of performing transesterification reactions useful for the production of biodiesel. However selection of the lipases capable of performing transesterification reactions is not easy and consequently very few biodiesel producing lipases are currently available. In this work we first isolated 1,016 lipolytic microorganisms by a qualitative plate assay. In a second step, lipolytic bacteria were analyzed using a colorimetric assay to detect the transesterification activity. Thirty of the initial lipolytic strains were selected for further characterization. Phylogenetic analysis revealed that 23 of the bacterial isolates were Gram negative and 7 were Gram positive, belonging to different clades. Biofuel production was analyzed and quantified by gas chromatography and revealed that 5 of the isolates produced biofuel with yields higher than 80% at benchtop scale. Chemical and viscosity analysis of the produced biofuel revealed that it differed from biodiesel. This bacterial-derived biofuel does not require any further downstream processing and it can be used directly in engines. The freeze-dried bacterial culture supernatants could be used at least five times for biofuel production without diminishing their activity. Therefore, these 5 isolates represent excellent candidates for testing biofuel production at industrial scale.

  1. Isolation of an antimicrobial compound produced by bacteria associated with reef-building corals

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    Jean-Baptiste Raina

    2016-08-01

    Full Text Available Bacterial communities associated with healthy corals produce antimicrobial compounds that inhibit the colonization and growth of invasive microbes and potential pathogens. To date, however, bacteria-derived antimicrobial molecules have not been identified in reef-building corals. Here, we report the isolation of an antimicrobial compound produced by Pseudovibrio sp. P12, a common and abundant coral-associated bacterium. This strain was capable of metabolizing dimethylsulfoniopropionate (DMSP, a sulfur molecule produced in high concentrations by reef-building corals and playing a role in structuring their bacterial communities. Bioassay-guided fractionation coupled with nuclear magnetic resonance (NMR and mass spectrometry (MS, identified the antimicrobial as tropodithietic acid (TDA, a sulfur-containing compound likely derived from DMSP catabolism. TDA was produced in large quantities by Pseudovibrio sp., and prevented the growth of two previously identified coral pathogens, Vibrio coralliilyticus and V. owensii, at very low concentrations (0.5 μg/mL in agar diffusion assays. Genome sequencing of Pseudovibrio sp. P12 identified gene homologs likely involved in the metabolism of DMSP and production of TDA. These results provide additional evidence for the integral role of DMSP in structuring coral-associated bacterial communities and underline the potential of these DMSP-metabolizing microbes to contribute to coral disease prevention.

  2. Characteristics of some fermentative bacteria from a thermophilic methane-producing fermenter

    Energy Technology Data Exchange (ETDEWEB)

    Varel, V.H.

    1984-01-01

    Anaerobic bacteria from a 55/sup 0/C methane-producing beef waste fermenter were enumerated, isolated, and characterized. Direct microscopic bacterial counts were 5.2-6.8 X 10/sup 10/ per g fermenter effluent. Using a nonselective roll-tube medium which contained 40% fermenter effluent, 8.5-14.1% of microscopic count was culturable. Deletion of fermenter effluent significantly reduced the viable count. Sixty-four randomly picked strains were characterized. All were pleomorphic, gram-negative, anaerobic rods, many of which were difficult to grow in liquid media. The strains were divided into 5 major groups based on glucose fermentation, hydrogen sulfide production, starch hydrolysis, fermentation products, and morphology. Glucose was fermented by 75% of the isolates, 76% utilized starch, 25% produced hydrogen sulfide, 76% produced hydrogen, 37% produced indole, 21% hydrolyzed gelatin, and 13% were sporeformers. Ethanol, lactate, formate, acetate, and hydrogen were common fermentation products. Twenty-four representative strains had 1-12 flagella. Growth was observed between 35 and 73/sup 0/C. These studies indicate that species diversity among the isolated organisms was low. 38 references, 3 tables.

  3. Selection and characterization of biofuel-producing environmental bacteria isolated from vegetable oil-rich wastes.

    Science.gov (United States)

    Escobar-Niño, Almudena; Luna, Carlos; Luna, Diego; Marcos, Ana T; Cánovas, David; Mellado, Encarnación

    2014-01-01

    Fossil fuels are consumed so rapidly that it is expected that the planet resources will be soon exhausted. Therefore, it is imperative to develop alternative and inexpensive new technologies to produce sustainable fuels, for example biodiesel. In addition to hydrolytic and esterification reactions, lipases are capable of performing transesterification reactions useful for the production of biodiesel. However selection of the lipases capable of performing transesterification reactions is not easy and consequently very few biodiesel producing lipases are currently available. In this work we first isolated 1,016 lipolytic microorganisms by a qualitative plate assay. In a second step, lipolytic bacteria were analyzed using a colorimetric assay to detect the transesterification activity. Thirty of the initial lipolytic strains were selected for further characterization. Phylogenetic analysis revealed that 23 of the bacterial isolates were Gram negative and 7 were Gram positive, belonging to different clades. Biofuel production was analyzed and quantified by gas chromatography and revealed that 5 of the isolates produced biofuel with yields higher than 80% at benchtop scale. Chemical and viscosity analysis of the produced biofuel revealed that it differed from biodiesel. This bacterial-derived biofuel does not require any further downstream processing and it can be used directly in engines. The freeze-dried bacterial culture supernatants could be used at least five times for biofuel production without diminishing their activity. Therefore, these 5 isolates represent excellent candidates for testing biofuel production at industrial scale.

  4. Reducing COD level on oily effluent by utilizing biosurfactant-producing bacteria

    Directory of Open Access Journals (Sweden)

    Daniela Franco Carvalho Jacobucci

    2009-08-01

    Full Text Available Two bacteria isolated from crude oil contaminated soil, Pantoea agglomerans and Planococcus citreus, produced biosurfactants utilizing 1.5% of kerosene and olive oil as the sole carbon sources, respectively. The bacteria and the biosurfactants produced were introduced to oily effluent, arising from margarine and soap industry. Emulsification activities were determined by increases in the absorbance of the oil-in-water emulsions at 610 nm, whereas the water-in-oil emulsions were expressed as the height (cm of the emulsion layers formed. The 72 h incubation experiment resulted in a COD (Chemical Oxygen Demand reduction of 76% with Planococcus citreus strain and 70% with Pantoea agglomerans.The COD reduction with bacterial biosurfactants was over 50% in 24 h of incubation. The COD reduction showed that these strains and the surfactants produced could be used in bioremediation processes.Duas bactérias isoladas de solo contaminado com derivados de petróleo, Pantoea agglomerans e Planococcus citreus, produzem biosurfactantes utilizando respectivamente 1.5% de querosene e óleo de oliva como únicas fontes de carbono. As bactérias e os biosurfactantes produzidos foram adicionados a um efluente oleoso obtido de uma indústria nacional de sabão e margarina. As atividades de emulsificação foram determinadas pelo aumento da absorbância das emulsões óleo em água a 610 nm, enquanto que as emulsões do tipo água em óleo foram expressas em centímetros, pela altura do halo de espumas formado. A redução da demanda química de oxigênio (COD mostra que as linhagens e os biosurfactantes produzidos podem ser utilizados em processos de biorremediação.

  5. Effects of Dietary Supplementation with Hainanmycin on Protein Degradation and Populations of Ammonia-producing Bacteria

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    Z. B. Wang

    2013-05-01

    Full Text Available An in vitro fermentation was conducted to determine the effects of hainanmycin on protein degradation and populations of ammonia-producing bacteria. The substrates (DM basis for in vitro fermentation consisted of alfalfa hay (31.7%, Chinese wild rye grass hay (28.3%, ground corn grain (24.5%, soybean meal (15.5% with a forage: concentrate of 60:40. Treatments were the control (no additive and hainanmycin supplemented at 0.1 (H0.1, 1 (H1, 10 (H10, and 100 mg/kg (H100 of the substrates. After 24 h of fermentation, the highest addition level of hainanmycin decreased total VFA concentration and increased the final pH. The high addition level of hainanmycin (H1, H10, and H100 reduced (p0.05. After 24 h of fermentation, H10 and H100 increased (p<0.05 concentrations of peptide nitrogen and AA nitrogen and proteinase activity, and decreased (p<0.05 NH3-N concentration and deaminase activity compared with control. Peptidase activitives were not affected by hainanmycin. Hainanmycin supplementation only inhibited the growth of Butyrivibrio fibrisolvens, which is one of the species of low deaminative activity. Hainanmycin supplementation also decreased (p<0.05 relative population sizes of hyper-ammonia-producing species, except for H0.1 on Clostridium aminophilum. It was concluded that dietary supplementation with hainanmycin could improve ruminal fermentation and modify protein degradation by changing population size of ammonia-producing bacteria in vitro; and the addition level of 10 mg/kg appeared to achieve the best results.

  6. Isolation of Human Intestinal Bacteria Capable of Producing the Bioactive Metabolite Isourolithin A from Ellagic Acid

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    María V. Selma

    2017-08-01

    Full Text Available Urolithins are intestinal microbial metabolites produced from ellagitannin- and ellagic acid-containing foods such as walnuts, strawberries, and pomegranates. These metabolites, better absorbed than their precursors, can contribute significantly to the beneficial properties attributed to the polyphenols ellagitannins and ellagic acid (EA. However, both the ability of producing the final metabolites in this catabolism (urolithins A, B and isourolithin A and the health benefits associated with ellagitannin consumption differ considerably among individuals depending on their gut microbiota composition. Three human urolithin metabotypes have been previously described, i.e., metabotype 0 (urolithin non-producers, metabotype A (production of urolithin A as unique final urolithin and metabotype B (urolithin B and/or isourolithin A are produced besides urolithin A. Although production of some intermediary urolithins has been recently attributed to intestinal species from Eggerthellaceae family named Gordonibacter urolithinfaciens and Gordonibacter pamelaeae, the identification of the microorganisms responsible for the complete transformation of EA into the final urolithins, especially those related to metabotype B, are still unknown. In the present research we illustrate the isolation of urolithin-producing strains from human feces of a healthy adult and their ability to transform EA into different urolithin metabolites, including isourolithin A. The isolates belong to a new genus from Eggerthellaceae family. EA transformation and urolithin production arisen during the stationary phase of the growth of the bacteria under anaerobic conditions. The HPLC-DAD-MS analyses demonstrated the sequential appearance of 3,8,9,10-tetrahydroxy-urolithin (urolithin M6, 3,8,9-trihydroxy-urolithin (urolithin C and 3,9-dihydroxy-urolithin (isourolithin A while 3,8-dihydroxy-urolithin (urolithin A and 3-hydroxy-urolithin (urolithin B were not detected. For the first time

  7. Risk factors for community-acquired urinary tract infection caused by ESBL-producing bacteria in children.

    Science.gov (United States)

    Kizilca, Ozgur; Siraneci, Rengin; Yilmaz, Alev; Hatipoglu, Nevin; Ozturk, Erkut; Kiyak, Aysel; Ozkok, Dilek

    2012-12-01

    The aim of the present study was to investigate the risk factors of antimicrobial resistance in children with urinary tract infection caused by extended-spectrum beta-lactamase (ESBL)-producing bacteria. A total of 344 patients diagnosed with urinary tract infection (UTI) between January 2008 and December 2009 were enrolled in this retrospective study. Causative microorganisms were ESBL-producing bacteria in 148 patients and non-ESBL-producing bacteria in 196 patients. There was no difference between the two groups regarding distribution of age, sex and length of follow up. The most frequent causative agent was Escherichia coli, of which 41.4% were ESBL producing. Among Klebsiella species, 53.2% were ESBL producing. The proportion of ESBL-producing bacteria that were resistant to antibiotics was 83.1% for trimethoprim/sulfamethoxazole, 18.2% for nitrofurantoin, 47.3% for quinolones, and 39.9% for aminoglycosides. For non-ESBL-producing bacteria, the resistance rate was 62.2% for trimethoprim/sulfamethoxazole, 4.6% for nitrofurantoin, 9.7% for quinolones, and 9.7% for aminoglycosides. Age <1 year, high UTI recurrence rate, long duration of prophylaxis, use of cephalosporins for prophylaxis, hospitalization within the previous 3 months and clean intermittent catheterization were found to be significant risk factors for ESBL-producing bacteria (P < 0.05). Logistic regression analysis identified age <1 year and high recurrence UTI rate to be independent risk factors, increasing the risk 1.74-fold and 2.25-fold, respectively. Recognition of the risk factors for ESBL-producing bacteria may be helpful to determine new policies in the management of UTI. Recurrence of UTI should be prevented especially in the first year of life, and prophylactic cephalosporins should be avoided. © 2012 The Authors. Pediatrics International © 2012 Japan Pediatric Society.

  8. Identification and quantification of antifungal compounds produced by lactic acid bacteria and propionibacteria.

    Science.gov (United States)

    Le Lay, Céline; Coton, Emmanuel; Le Blay, Gwenaëlle; Chobert, Jean-Marc; Haertlé, Thomas; Choiset, Yvan; Van Long, Nicolas Nguyen; Meslet-Cladière, Laurence; Mounier, Jérôme

    2016-12-19

    Fungal growth in bakery products represents the most frequent cause of spoilage and leads to economic losses for industrials and consumers. Bacteria, such as lactic acid bacteria and propionibacteria, are commonly known to play an active role in preservation of fermented food, producing a large range of antifungal metabolites. In a previous study (Le Lay et al., 2016), an extensive screening performed both in vitro and in situ allowed for the selection of bacteria exhibiting an antifungal activity. In the present study, active supernatants against Penicillium corylophilum and Aspergillus niger were analyzed to identify and quantify the antifungal compounds associated with the observed activity. Supernatant treatments (pH neutralization, heating and addition of proteinase K) suggested that organic acids played the most important role in the antifungal activity of each tested supernatant. Different methods (HPLC, mass spectrometry, colorimetric and enzymatic assays) were then applied to analyze the supernatants and it was shown that the main antifungal compounds corresponded to lactic, acetic and propionic acids, ethanol and hydrogen peroxide, as well as other compounds present at low levels such as phenyllactic, hydroxyphenyllactic, azelaic and caproic acids. Based on these results, various combinations of the identified compounds were used to evaluate their effect on conidial germination and fungal growth of P. corylophilum and Eurotium repens. Some combinations presented the same activity than the bacterial culture supernatant thus confirming the involvement of the identified molecules in the antifungal activity. The obtained results suggested that acetic acid was mainly responsible for the antifungal activity against P. corylophilum and played an important role in E. repens inhibition.

  9. Sugar-coated: exopolysaccharide producing lactic acid bacteria for food and human health applications.

    Science.gov (United States)

    Ryan, P M; Ross, R P; Fitzgerald, G F; Caplice, N M; Stanton, C

    2015-03-01

    The human enteric microbiome represents a veritable organ relied upon by the host for a range of metabolic and homeostatic functions. Through the production of metabolites such as short chain fatty acids (SCFA), folate, vitamins B and K, lactic acid, bacteriocins, peroxides and exopolysaccharides, the bacteria of the gut microbiome provide nutritional components for colonocytes, liver and muscle cells, competitively exclude potential pathogenic organisms and modulate the hosts immune system. Due to the extensive variation in structure, size and composition, microbial exopolysaccharides represent a useful set of versatile natural ingredients for the food industrial sector, both in terms of their rheological properties and in many cases, their associated health benefits. The exopolysaccharide-producing bacteria that fall within the 35 Lactobacillus and five Bifidobacterium species which have achieved qualified presumption of safety (QPS) and generally recognised as safe (GRAS) status are of particular interest, as their inclusion in food products can avoid considerable scrutiny. In addition, additives commonly utilised by the food industry are becoming unattractive to the consumer, due to the demand for a more 'natural' and 'clean labelled' diet. In situ production of exopolysaccharides by food-grade cultures in many cases confers similar rheological and sensory properties in fermented dairy products, as traditional additives, such as hydrocolloids, collagen and alginate. This review will focus on microbial synthesis of exopolysaccharides, the human health benefits of dietary exopolysaccharides and the technofunctional applications of exopolysaccharide-synthesising microbes in the food industry.

  10. Antimicrobial peptides targeting Gram-negative pathogens, produced and delivered by lactic acid bacteria.

    Science.gov (United States)

    Volzing, Katherine; Borrero, Juan; Sadowsky, Michael J; Kaznessis, Yiannis N

    2013-11-15

    We present results of tests with recombinant Lactococcus lactis that produce and secrete heterologous antimicrobial peptides with activity against Gram-negative pathogenic Escherichia coli and Salmonella . In an initial screening, the activities of numerous candidate antimicrobial peptides, made by solid state synthesis, were assessed against several indicator pathogenic E. coli and Salmonella strains. Peptides A3APO and Alyteserin were selected as top performers based on high antimicrobial activity against the pathogens tested and on significantly lower antimicrobial activity against L. lactis . Expression cassettes containing the signal peptide of the protein Usp45 fused to the codon-optimized sequence of mature A3APO and Alyteserin were cloned under the control of a nisin-inducible promoter PnisA and transformed into L. lactis IL1403. The resulting recombinant strains were induced to express and secrete both peptides. A3APO- and Alyteserin-containing supernatants from these recombinant L. lactis inhibited the growth of pathogenic E. coli and Salmonella by up to 20-fold, while maintaining the host's viability. This system may serve as a model for the production and delivery of antimicrobial peptides by lactic acid bacteria to target Gram-negative pathogenic bacteria populations.

  11. Prevalence and emergence of carbapenemases-producing Gram-negative bacteria in Mediterranean basin.

    Science.gov (United States)

    Mathlouthi, Najla; Al-Bayssari, Charbel; Bakour, Sofiane; Rolain, Jean Marc; Chouchani, Chedly

    2017-02-01

    The emergence and the global spread of carbapenemases concern to health services worldwide. Their celestial rise among Gram-negative bacilli has challenged both the scientific and pharmaceutical sectors. Indeed, infections caused by these bacteria have limited treatment options and have been associated with high mortality and morbidity rates. Carbapenemase producers are mainly identified among Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii and still mostly in hospital settings and rarely in the community. They are closely related to KPC, VIM, IMP, NDM, and OXA-48 types. The encoding genes are mostly plasmid located and associated with various mobile genetic elements. The Mediterranean area is of interest due to a great diversity and population mixing. The prevalence of carbapenemases is particularly high and variant among countries, partially depending on the population exchange relationship between the regions and the possible reservoirs of each carbapenemase. This review described the epidemiology of carbapenemases in this region of the world highlighting the worrisome situation and the need to screen and detect these enzymes to prevent and control their dissemination especially as it is clear that very few novel antibiotics will be introduced in the next few years, making the dissemination of carbapenem-resistant Gram-negative bacteria of crucial importance worldwide.

  12. ISOLATION AND IDENTIFICATION OF LACTIC ACID PRODUCING BACTERIA FROM CAMEL MILK

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    Toqeer Ahmad, Rashida Kanwal, Izhar Hussain Athar1, Najam Ayub

    2002-03-01

    Full Text Available Lactic acid bacteria (LAB were isolated from camel milk by culturing the camel milk on specific media and pure culture was obtained by sub culturing. Purification of culture was confirmed by Gram's staining and identified by different bio-chemical tests. Camel milk contains lactic acid producing bacteria including Strpptococci such as S. cremoris and S. lactis and Lactobacilli such as L. acidophilus L. acidophilus grows more rapidly in camel milk than others as its growth is supported by camel milk. A variety of food can be preserved by lactic acid fermentation, so starter culture was prepared from strains which were isolated from camel milk. Camel and buffalo's milk cheese was prepared by using starter culture. The strains isolated from camel milk were best for acid production and can coagulate the milk in less lime. Camel milk cheese was prepared and compared with buffalo's milk cheese. It is concluded that cheese can be prepared successfully from camel milk and better results can be obtained by coagulating milk with starter culture.

  13. Application of bacteriophages to reduce biofilms formed by hydrogen sulfide producing bacteria on surfaces in a rendering plant.

    Science.gov (United States)

    Gong, Chao; Jiang, Xiuping

    2015-08-01

    Hydrogen sulfide producing bacteria (SPB) in raw animal by-products are likely to grow and form biofilms in the rendering processing environments, resulting in the release of harmful hydrogen sulfide (H2S) gas. The objective of this study was to reduce SPB biofilms formed on different surfaces typically found in rendering plants by applying a bacteriophage cocktail. Using a 96-well microplate method, we determined that 3 SPB strains of Citrobacter freundii and Hafnia alvei are strong biofilm formers. Application of 9 bacteriophages (10(7) PFU/mL) from families of Siphoviridae and Myoviridae resulted in a 33%-70% reduction of biofilm formation by each SPB strain. On stainless steel and plastic templates, phage treatment (10(8) PFU/mL) reduced the attached cells of a mixed SPB culture (no biofilm) by 2.3 and 2.7 log CFU/cm(2) within 6 h at 30 °C, respectively, as compared with 2 and 1.5 log CFU/cm(2) reductions of SPB biofilms within 6 h at 30 °C. Phage treatment was also applied to indigenous SPB biofilms formed on the environmental surface, stainless steel, high-density polyethylene plastic, and rubber templates in a rendering plant. With phage treatment (10(9) PFU/mL), SPB biofilms were reduced by 0.7-1.4, 0.3-0.6, and 0.2-0.6 log CFU/cm(2) in spring, summer, and fall trials, respectively. Our study demonstrated that bacteriophages could effectively reduce the selected SPB strains either attached to or in formed biofilms on various surfaces and could to some extent reduce the indigenous SPB biofilms on the surfaces in the rendering environment.

  14. A Study on Infections Caused By Metallo Beta Lactamase Producing Gram Negative Bacteria in Intensive Care Unit Patients

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    Debasrita Chakraborty

    2010-01-01

    Full Text Available Problem statement: Metallo Beta Lactamse (MBL producing bacteria is gradually increasing throughout the globe. There is no report of MBL producing bacteria from the city of Kolkata so far although it is a very big metropolice city in India. Thus this study was aimed to investigate the impact of this highly virulent group of bacteria in this city. Approach: In this experiment we studied the prevalence, following standard methods of isolation and identification techniques of these bacteria from clinical materials and also studied some characteristics and clinical data in relation to MBL producing bacterial infections in this locality. Results: It was seen that a high prevalence of MBL producing bacteria was present in this city and there were many differences between MBL producing bacterial infection in comparison to the MBL non producing bacterial infection, particularly in relation to age distribution, sex predominance, mortality rate, hematological changes, nature of primary diseases in which infection occurred. There were also some electron microscopic morphological alterations in MBL positive bacterial isolates. Conclusion: This study confirmed significant occurrence of MBL producing bacterial infections in Kolkata showing distinct clinic microbial changes in this type of infection.

  15. Optimization of Chlorella vulgaris and bioflocculant-producing bacteria co-culture: enhancing microalgae harvesting and lipid content.

    Science.gov (United States)

    Wang, Y; Yang, Y; Ma, F; Xuan, L; Xu, Y; Huo, H; Zhou, D; Dong, S

    2015-05-01

    Microalgae are a sustainable bioresource, and the biofuel they produce is widely considered to be an alternative to limited natural fuel resources. However, microalgae harvesting is a bottleneck in the development of technology. Axenic Chlorella vulgaris microalgae exhibit poor harvesting, as expressed by a flocculation efficiency of 0·2%. This work optimized the co-culture conditions of C. vulgaris and bioflocculant-producing bacteria in synthetic wastewater using response surface methodology (RSM), thus aiming to enhance C. vulgaris harvesting and lipid content. Three significant process variables- inoculation ratio of bacteria and microalgae, initial glucose concentration, and co-culture time- were proposed in the RSM model. F-values (3·98/8·46) and R(2) values (0·7817/0·8711) both indicated a reasonable prediction by the RSM model. The results showed that C. vulgaris harvesting efficiency reached 45·0-50·0%, and the lipid content was over 21·0% when co-cultured with bioflocculant-producing bacteria under the optimized culture conditions of inoculation ratio of bacteria and microalgae of 0·20-0·25, initial glucose concentration of microalgae harvesting and cost-effective microalgal bioproducts, and confirmed the promising prospect of introducing bioflocculant-producing bacteria into microalgae bioenergy production. This work optimized the co-culture conditions of microalgae (C. vulgaris) and bioflocculant-producing bacteria (F2, Rhizobium radiobacter) in synthetic wastewater using response surface methodology, aiming to enhance C. vulgaris harvesting and lipid produced content. Bioflocculant-producing microbes are environmentally friendly functional materials. They avoid the negative effects of traditional chemical flocculants. This work provided new insights into microalgae harvesting and cost-effective production of microalgal bioproducts, and confirmed the promising prospect of introducing bioflocculant-producing bacteria into microalgae

  16. Comparative analysis of hydrogen-producing bacteria and its immobilized cells for characteristics of hydrogen production

    Institute of Scientific and Technical Information of China (English)

    王相晶; 任南琪; 向文胜; 王爱杰; 林明; 郭婉茜

    2003-01-01

    A strain of hydrogen producing bacteria was immobilized by polyvinyl alcohol-boric acid method,with the addition of a small amount of calcium alginate. The immobilized cells were insensitive to the presence of traces of O2. Moreover, the immobilized cells increased both the evolution rate and the yield of hydrogen production. Batch experiments with a medium containing 10 g/L glucose demonstrated the yields of hydrogen production by the immobilized and free cells were 2.14 mol/mol glucose and 1.69 mol/mol glucose, respectively.In continuous cultures atmedium retention time of 2. 0 h, the yield and the evolution rate of hydrogen producmedium retention time of 6. 0 h, the yield and the evolution rate of hydrogen production by free cells were only 1.75 mol/mol glucose and 362.9ml/(L·h),respectively.

  17. Meat spoilage: a critical review of a neglected alteration due to ropy slime producing bacteria

    Directory of Open Access Journals (Sweden)

    Maria F. Iulietto

    2015-07-01

    Full Text Available The shelf-life of a product is the period of time during which the food retains its qualitative characteristics. Bacteria associated with meat spoilage produce unattractive odours and flavours, discolouration, gas and slime. There are several neglected alterations that deserve more attention from food business operators and competent authorities. Ropy slime is a typical alteration of the surface of vacuum and modified atmosphere packed cooked meat products, that causes major economic losses due to the increasingly sophisticated consumer requirements. This is a review article that aims at raising awareness of an old problem of new concern, in the light of new advances and trends for understanding the aetiology of the phenomenon, the origins of contamination and the prevention measures.

  18. Utilization of Vinegar for Isolation of Cellulose Producing Acetic Acid Bacteria

    Science.gov (United States)

    Aydin, Y. Andelib; Aksoy, Nuran Deveci

    2010-06-01

    Wastes of traditionally fermented Turkish vinegar were used in the isolation of cellulose producing acetic acid bacteria. Waste material was pre-enriched in Hestrin-Schramm medium and microorganisms were isolated by plating dilution series on HS agar plates The isolated strains were subjected to elaborate biochemical and physiological tests for identification. Test results were compared to those of reference strains Gluconacetobacter xylinus DSM 46604, Gluconacetobacter hansenii DSM 5602 and Gluconacetobacter liquefaciens DSM 5603. Seventeen strains, out of which only three were found to secrete the exopolysaccharide cellulose. The highest cellulose yield was recorded as 0.263±0.02 g cellulose L-1 for the strain AS14 which resembled Gluconacetobacter hansenii in terms of biochemical tests.

  19. Characterization of urease and carbonic anhydrase producing bacteria and their role in calcite precipitation.

    Science.gov (United States)

    Achal, Varenyam; Pan, Xiangliang

    2011-03-01

    Urease and carbonic anhydrase (CA) are key enzymes in the chemical reaction of living organisms and have been found to be associated with calcification in a number of microorganisms and invertebrates. Three bacterial strains designated as AP4, AP6, and AP9 were isolated from highly alkaline soil samples using the enrichment culture technique. On the basis of various physiological tests and 16S rRNA sequence analysis, these three bacteria were identified as Bacillus sp., B. megaterium, and B. simplex. Further, these Bacillus species have been characterized for the production of urease and CA in the process of biocalcification. One of the isolates, AP6 produced 553 U/ml of urease and 5.61 EU/ml CA. All the strains were able to produce significant amount of exopolymeric substances and biofilm. Further, efficacy of these strains was tested for calcite production ability and results were correlated with urease and CA. Isolate AP6 precipitated 2.26 mg calcite/cell dry mass (mg). Our observations strongly suggest that it is not only urease but CA also plays an important role in microbially induced calcium carbonate precipitation process. The current work demonstrates that urease and CA producing microbes can be utilized in biocalcification as a sealing agent for filling the gaps or cracks and fissures in constructed facilities and natural formations alike.

  20. POLY (β-HYDROXYALKANOATES): NATURAL BIOCOMPATIBLE AND BIODEGRADABLE POLYESTERS PRODUCED BY BACTERIA

    Institute of Scientific and Technical Information of China (English)

    ROBERT W.LENZ; RICHARD A.GROSS; HELMUT BRANDL; R.CLINTON FULLER

    1989-01-01

    A wide variety of different types of microorganisms are known to produce intracellular energy and carbon storage products, which have been generally described as being poly (β-hydroxybutyrate ), PHB, but which are, more often than not, copolymers containing different alkyl groups at the β-position. Hence, PHB belongs to the family ofpoly (β-hydroxyalkanoastes), PHA, all of which are usually formed as intracellular inclusions in bacteria under unbalanced growth conditions. Recently, it became of industrial interest to evaluate these PHA polyesters as natural biodegradable and biocompatible plastics for a wide range of possible applications, such as surgical sutures or packaging containers. For industrial applications, the controlled incorporation of repeating units with different chain lengths into a series ofcopolymers is desirable in order to produce polyesters with a range of material properties because physical and chemical characteristics depend strongly on the polymer composition. Such "tailor- made" copolymers can be produced under controlled growth conditions in that, if a defined mixture of substrates for a certain type of microorganisms is supplied, a well defined and reproducible copolymer is formed.

  1. Water Kefir grain as a source of potent dextran producing lactic acid bacteria

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    Davidović Slađana Z.

    2015-01-01

    Full Text Available Water kefir is abeverage fermented by a microbial consortium captured in kefir grains. The kefir grains matrix is composed of polysaccharide, primarily dextran, whichis produced by members of the microbial consortium. In this study, we have isolated lactic acid bacteria (LAB from non-commercial water kefir grains (from Belgrade, Serbia and screened for dextran production. Among twelve Lisolates threeproduced slime colonies on modified MRS (mMRS agar containing sucrose instead of glucoseand were presumed to produce dextran. Three LABwere identified based on morphological, physiological and biochemical characteristics and 16S rRNA sequencing as Leuconostoc mesenteroides(strains T1 and T3 and Lactobacillus hilgardii (strain T5. The isolated strains were able to synthesize a substantial amount of dextran in mMRS broth containing 5% sucrose. Maximal yields (11.56, 18.00 and 18.46 g/l were obtained after 16h, 20h and 32h for T1, T3 and T5, respectively. Optimal temperature for dextran production was 23oC for two Leuconostoc mesenteroides strains and 30oC for Lactobacillus hilgardii strain. The produced dextrans were identified based on paper chromatography while the main structure characteristics of purified dextranwere observed by FT-IR spectroscopy. Our study shows that water kefir grains are a natural source of potent dextranproducing LAB. [Projekat Ministarstva nauke Republike Srbije, br. TR 31035

  2. Degradation of Polycyclic Aromatic Hydrocarbon Pyrene by Biosurfactant-Producing Bacteria Gordonia cholesterolivorans AMP 10

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    Tri Handayani Kurniati

    2016-12-01

    Full Text Available Pyrene degradation and biosurfactant activity by a new strain identified as Gordonia cholesterolivorans AMP 10 were studied. The strain grew well and produced effective biosurfactants in the presence of glucose, sucrose, and crude oil. The biosurfactants production was detected by the decreased surface tension of the medium and emulsification activity.  Analysis of microbial growth parameters showed that AMP10 grew best at 50 µg mL-1 pyrene concentration, leading to 96 % degradation of pyrene within 7 days. The result of nested PCR analysis revealed that this isolate possessed the nahAc gene which encodes dioxygenase enzyme for initial degradation of Polycyclic Aromatic Hydrocarbon (PAH. Observation of both tensio-active and emulsifying activities indicated that biosurfactants which produced by AMP 10 when grown on glucose could lower the surface tension of medium from 71.3 mN/m to 24.7 mN/m and formed a stable emulsion in used lubricant oil with an emulsification index (E24 of 74%. According to the results, it is suggested that the bacterial isolates G. cholesterolivorans AMP10 are suitable candidates for bioremediation of PAH-contaminated environments.How to CiteKurniati, T. H.,  Rusmana, I. Suryani, A. & Mubarik, N. R. (2016. Degradation of Polycyclic Aromatic Hydrocarbon Pyrene by Biosurfactant-Producing Bacteria Gordonia cholesterolivorans AMP 10. Biosaintifika: Journal of Biology & Biology Education, 8(3, 336-343. 

  3. Isolation of alkalophilic CGTase-producing bacteria and characterization of cyclodextrin-glycosyltransferase

    Directory of Open Access Journals (Sweden)

    Higuti lma Hiroko

    2003-01-01

    Full Text Available One hundred and twenty five soil samples were collected from the regions of roots of corn, cassava, potato, bean, sugar cane, soya, and pumpkin. From these, 75 strains were isolated that produced a yellowish halo surrounding the colonies, due to a phenolphtalein-cyclodextrin (CD complex, and these were selected as alkalophilic CGTase-producing bacteria. All the 75 strains were identified as Bacillus firmus by microscopy and biochemical tests. The activity of the CGTase's varied from 2² to 2(10 dilutions,when assayed by CD-trichloroethylene (TCE-complex precipitation. Strain 31 that produced the enzyme at the higher level was selected, and its enzyme was partially purified by starch adsorption (x 17 in a yield of 51%. Maximum enzyme activity occurred at pH 5.5 and 8.5. At pH 5.5, the optimum temperature was 60°C. On increased from 30°C to 85°C, the thermodynamic parameter for activation energy was 8.27 kcal.mol-1. The enzyme was inhibited by Ca2+, Mg2+, Fe2+, Cu2+, Mn2+, and Zn2+.

  4. Heat resistance of histamine-producing bacteria in irradiated tuna loins.

    Science.gov (United States)

    Enache, Elena; Kataoka, Ai; Black, D Glenn; Weddig, Lisa; Hayman, Melinda; Bjornsdottir-Butler, Kristin

    2013-09-01

    Consumption of foods high in biogenic amines leads to an illness known as histamine, or scombrotoxin, poisoning. The illness is commonly associated with consumption of fish with high levels of histamine ( $ 500 ppm). The objective of this study was to determine and compare the heat resistance of five histamine-producing bacteria in irradiated albacore tuna loins. Heat-resistance parameters (D- and z-values) were determined for Morganella morganii, Raoultella planticola, Hafnia alvei, and Enterobacter aerogenes. D- or z-values were not determined for Photobacterium damselae, which was the most heat-sensitive organism in this study. P. damselae declined > 5.9 log CFU/g after a heat treatment of 50°C for 10 min, 54°C for 3 min, and 56°C for 0.5 min. M. morganii was the most heat-resistant histamine-producing bacteria in albacore tuna loins, followed by E. aerogenes, H. alvei, and R. planticola. M. morganii and E. aerogenes had the highest D(50°C), 49.7 ± 17.57 and 51.8 ± 17.38 min, respectively. In addition, M. morganii had the highest D-values for all other temperatures (54, 56, and 58°C) tested. D- and zvalues were also determined for M. morganii in skipjack tuna. While no significant (P > 0.05) difference was observed between D(54°C) and D(56°C) of M. morganii in either albacore or skipjack tuna, the D(58°C) (0.4 ± 0.17 min) was significantly lower (P canned-tuna processing environments.

  5. Screening and identification of polyhydroxyalkanoates producing bacteria and biochemical characterization of their possible application.

    Science.gov (United States)

    Sangkharak, Kanokphorn; Prasertsan, Poonsuk

    2012-01-01

    Polyhydroxyalkanoates (PHAs) accumulating bacteria were isolated under various selective conditions such as pH, salt concentrations and types of heavy metal. Fifty strains of bacterial isolates were found to belong to Bacillus, Proteus, Pseudomonas, Aeromonas, Alcaligenes and Chromobacterium, based on phenotypical features and genotypic investigation. Only twenty five bacterial isolates were selected and observed for the production of PHAs. Interestingly, bacteria belonging to Firmucutes Bacillus sp. produced a high amount of PHAs. The maximum PHAs were accumulated by B. licheniformis PHA 007 at 68.80% of dry cell weight (DCW). Pseudomonas sp., Aeromonas sp., Alcaligenes sp. and Chromobacterium sp. were recorded to produce a moderate amount of PHAs, varying from 10.00-44.32% of DCW. The enzymatic activity was preliminarily analyzed by the ratio of the clear zone diameter to colony diameter. Bacillus gave the highest ratio of hydrolysis zone which corresponds to the highest hydrolytic enzyme activities. Bacillus licheniformis PHA 007 had the highest lipase and protease activity at 2.1 and 5.1, respectively. However, the highest amylase activity was observed in Bacillus sp. PHA 023 at 1.4. Determination of metabolic characteristics was also investigated to check for their ability to consume a wide range of substrates. Bacillus, Aeromonas sp. and Alcaligenes sp. had great ability to utilize a variety of substrates. To decrease high PHA cost, different sources of cheap substrates were tested for the production of PHAs. Bacillus cereus PHA 008 gave the maximal yield of PHA production (64.09% of DCW) when cultivated in anaerobically treated POME. In addition, the accumulation of PHA copolymers such as 3-hydroxyvalerate and 3-hydroxyhexanoate was also observed in Bacillus and Pseudomomas sp. strain 012 and 045, respectively. Eight of the nine isolates accumulated a significant amount of PHAs when inexpensive carbon sources were used as substrates. Here it varied from 1

  6. Prevalence of extended-spectrum beta-lactamase-producing bacteria in food

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    Tham J

    2012-10-01

    Full Text Available Johan Tham,1 Mats Walder,2 Eva Melander,2,3 Inga Odenholt11Infectious Diseases Unit, Department of Clinical Sciences, 2Medical Microbiology, Department of Laboratory Medicine, Lund University, Malmö, Sweden; 3Department of Infection Control, Laboratory Medicine, Skåne County, SwedenAbstract: Extended-spectrum β-lactamase (ESBL-producing Enterobacteriaceae with Cefotaximase–München (CTX-M enzymes are rapidly increasing worldwide and pose a threat to health care. ESBLs with CTX-M enzymes have been isolated from animals and different food products, but it is unknown if food imported from the Mediterranean area may be a possible reservoir of these bacteria. During 2007–2008, swab samples from food across different retail outlets (mostly food from the Mediterranean countries and Swedish chicken were collected. Escherichia coli strains from Swedish meat and E. coli isolates from unspecified food from a Swedish food testing laboratory were also examined. In 349 of the 419 swab samples, growth of Enterobacteriaceae was found. In most of the samples, there was also growth of Gram-negative environmental bacteria. Air dry-cured products contained significantly less Enterobacteriaceae isolates compared to lettuces; however, none of the examined Enterobacteriaceae harbored ESBLs. This study did not support the theory that imported food from the Mediterranean area or Swedish domestic food might constitute an important vehicle for the dissemination of ESBL-producing Enterobacteriaceae; however, a spread from food to humans may have occurred after 2008.Keywords: ESBL, antibiotic resistance, zoonosis, food, Enterobacteriaceae

  7. Characterization of N-Acylhomoserine Lactones Produced by Bacteria Isolated from Industrial Cooling Water Systems

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    Noriya Okutsu

    2015-12-01

    Full Text Available The cooling water systems are used to remove heat generated in the various industries. Biofouling of the cooling water systems causes blocking of condenser pipes and the heat exchanger tubes. In many Gram-negative bacteria, N-acylhomoserine lactone (AHL are used as quorum-sensing signal molecule and associated with biofilm formation. To investigate the relationship between quorum sensing and biofouling in the cooling water system, we isolated a total of 192 bacterial strains from the five cooling water systems, and screened for AHL production. Seven isolates stimulated AHL-mediated purple pigment production in AHL reporter strain Chromobacterium violaceum CV026 or VIR07. Based on their 16S rRNA gene sequences, AHL-producing isolates were assigned to Aeromonas hydrophila, Lysobacter sp., Methylobacterium oryzae, and Bosea massiliensis. To the best of our knowledge, B. massiliensis and Lysobacter sp. have not been reported as AHL-producing species in the previous researches. AHLs extracted from the culture supernatants of B. massiliensis and Lysobacter sp. were identified by liquid chromatography-mass spectrometry. AHLs produced by B. massiliensis were assigned as N-hexanoyl-l-homoserine lactone (C6-HSL, N-(3-oxohexanoyl-l-homoserine lactone (3-oxo-C6-HSL, and N-(3-oxooctanoyl-l-homoserine lactone (3-oxo-C8-HSL. AHLs produced by Lysobacter sp. were assigned as N-decanoyl-l-homoserine lactone (C10-HSL and N-(3-oxodecanoyl-l-homoserine lactone (3-oxo-C10-HSL. This is the first report of identification of AHLs produced by B. massiliensis and Lysobacter sp. isolated from the cooling water system.

  8. H2 Reconstitution

    Science.gov (United States)

    Skipper, Mike

    2002-02-01

    The high power microwave program at the Air Force Research Laboratory (AFRL) includes high power source development in narrow band and wideband technologies. The H2 source is an existing wideband source that was developed at the AFRL. A recent AFRL requirement for a wideband impulse generator to use in materials tests has provided the need to update the H2 source for the current test requirements. The H2 source is composed of a dual resonant transformer that charges a short length of coaxial transmission line. The transmission line is then discharged into an output coaxial transmission line with a self-break hydrogen switch. The dual resonant transformer is driven by a low inductance primary capacitor bank operating through a self-break gas switch. The upgrade of the coaxial hydrogen output switch is the focus of this report. The hydrogen output switch was developed through extensive electrical and mechanical simulations. The switch insulator is made of Ultem 2300 and is designed to operate with a mechanical factor of safety equal to 4.0 at 1,000 psi. The design criteria, design data and operational data will be presented.

  9. The identification of 2,4-diacetylphloroglucinol as an antifungal metabolite produced by cutaneous bacteria of the salamander Plethodon cinereus.

    Science.gov (United States)

    Brucker, Robert M; Baylor, Cambria M; Walters, Robert L; Lauer, Antje; Harris, Reid N; Minbiole, Kevin P C

    2008-01-01

    Beneficial bacteria that live on salamander skins have the ability to inhibit pathogenic fungi. Our study aimed to identify the specific chemical agent(s) of this process and asked if any of the antifungal compounds known to operate in analogous plant-bacteria-fungi systems were present. Crude extracts of bacteria isolated from salamander skin were exposed to HPLC, UV-Vis, GC-MS, and HR-MS analyses. These investigations show that 2,4-diacetylphloroglucinol is produced by the bacteria isolate Lysobacter gummosus (AB161361), which was found on the red-backed salamander, Plethodon cinereus. Furthermore, exposure of the amphibian fungal pathogen, Batrachochytrium dendrobatidis (isolate JEL 215), to different concentrations of 2,4-diacetylphloroglucinol resulted in an IC50 value of 8.73 microM, comparable to crude extract concentrations. This study is the first to show that an epibiotic bacterium on an amphibian species produces a chemical that inhibits pathogenic fungi.

  10. Effects of transgenic fructan-producing potatoes on the community structure of rhizosphere and phyllosphere bacteria.

    Science.gov (United States)

    Becker, Regina; Behrendt, Undine; Hommel, Bernd; Kropf, Siegfried; Ulrich, Andreas

    2008-11-01

    The rhizosphere and phyllosphere microbial communities of transgenic potatoes producing fructan were studied in comparison with isogenic controls and conventional varieties in a field release experiment over a period of 3 years. Population densities and 16S rRNA gene-based terminal restriction fragment length polymorphism (T-RFLP) analysis of the rhizosphere bacterial community only displayed the influence of annual and seasonal effects and the influence of field heterogeneity. In contrast, the T-RFLP analysis of the phyllosphere bacteria revealed in two of the 3 years significant differences in the community structure between the transgenic lines producing inulin and the other variants. This effect was studied in more detail through the analysis of bacterial isolates and a 16S rRNA gene clone library obtained from a transgenic line and the control. Both methods revealed a lower genetic diversity in the transgenic line and changes in the abundance of several bacterial groups. The isolates of the transgenic line were dominated by Bacilli, whereas most of the control isolates represented Actinobacteria. The clones were dominated by Proteobacteria, with main differences between both variants in Deltaproteobacteria, Bacilli and Bacteroidetes. However, all in all, the impact of the transgenic lines did not exceed the natural variability of the phyllosphere community structure on potato plants.

  11. BIOCHEMICAL CHARACTERISTICS OF LACTIC ACID PRODUCING BACTERIA AND PREPARATION OF CAMEL MILK CHEESE BY USING STARTER CULTURE

    OpenAIRE

    T. Ahmed and R. Kanwal

    2004-01-01

    Lactic acid bacteria (LAB) were isolated from camel milk by culturing the milk on specific media and pure culture was obtained by sub-culturing. Purification of culture was confirmed by Gram’s staining and identified by different biochemical tests. Camel milk contained lactic acid producing bacteria like Streptococci such as S. cremoris and S. lactis and Lactobacilli such as L. acidophilus. L. acidophilus grew more rapidly in camel milk than others as its growth was supported by camel milk...

  12. Properties of low-fat ultra-filtered cheeses produced with probiotic bacteria

    Directory of Open Access Journals (Sweden)

    Miočinović Jelena

    2014-01-01

    Full Text Available Probiotics are live microorganisms that in certain numbers may confer a health benefit on the host. Nowadays, there are many dairy products on the market, especially fermented milks, with probiotics, and their popularity is rising. The aim of this article was to investigate the viability of commercial probiotic bacteria (Lactobacillus acidophilus LAFTI®L10 i Bifidobacterium lactis LAFTI®B94, DSM, Netherland as well as their influence on the changes of composition, pH, proteolysis, microbiological status and sensory properties of low-fat ultra-filtered (UF cheeses within 2 months of ripening. Low-fat cast ultra-filtered (UF cheeses were produced according to the defined production procedure by mixing UF milk protein powder, skim milk and cream, without (control cheese A and with adjunct probiotic culture (cheese B. The compositional parameters (milk fat, proteins and dry-matter content, pH, proteolysis parameters (water soluble nitrogen, nitrogen soluble in 5% PTA, urea and SDS PAG electrophoresis, as well as the numbers of starters and probiotic bacteria, were determined during ripening. In addition, sensory evaluations of cheeses were performed throughout the ripening time. A significant influence of probiotic strains on the composition, pH and primary proteolysis of cheese during ripening was not found. The counts of commercial probiotic bacteria were maintained at high levels (>107 cfug-1 during the overall ripening period, as a prerequisite of their therapeutic effects. The adjunct probiotic cultures enhanced the rate of secondary proteolysis, which was shown by the significantly higher levels of PTAN/TN of experimental compared to the control cheeses. The sensory evaluation showed that the overall aroma of low-fat cheeses was remarkably improved by the addition of the probiotic cultures used. Based on the results it can be concluded that the low-fat UF cheeses differ in good dietetic and functional properties as well as very acceptable

  13. Hydrogen and carbon isotope systematics in hydrogenotrophic methanogenesis under H2-limited and H2-enriched conditions: implications for the origin of methane and its isotopic diagnosis

    Science.gov (United States)

    Okumura, Tomoyo; Kawagucci, Shinsuke; Saito, Yayoi; Matsui, Yohei; Takai, Ken; Imachi, Hiroyuki

    2016-12-01

    Hydrogen and carbon isotope systematics of H2O-H2-CO2-CH4 in hydrogenotrophic methanogenesis and their relation to H2 availability were investigated. Two H2-syntrophic cocultures of fermentatively hydrogenogenic bacteria and hydrogenotrophic methanogens under conditions of pure cultures of hydrogenotrophic methanogens under conditions of 105 Pa-H2 were tested. Carbon isotope fractionation between CH4 and CO2 during hydrogenotrophic methanogenesis was correlated with pH2, as indicated in previous studies. The hydrogen isotope ratio of CH4 produced during rapid growth of the thermophilic methanogen Methanothermococcus okinawensis under high pH2 conditions ( 105 Pa) was affected by the isotopic composition of H2, as concluded in a previous study of Methanothermobacter thermautotrophicus. This " {δ D}_{{H}_2} effect" is a possible cause of the diversity of previously reported values for hydrogen isotope fractionation between CH4 and H2O examined in H2-enriched culture experiments. Hydrogen isotope fractionation between CH4 and H2O, defined by (1000 + {δ D}_{{CH}_4} )/(1000 + {δ D}_{{H}_2O} ), during hydrogenotrophic methanogenesis of the H2-syntrophic cocultures was in the range 0.67-0.69. The hydrogen isotope fractionation of our H2-syntrophic dataset overlaps with those obtained not only from low- pH2 experiments reported so far but also from natural samples of "young" methane reservoirs (0.66-0.74). Conversely, such hydrogen isotope fractionation is not consistent with that of "aged" methane in geological samples (≥0.79), which has been regarded as methane produced via hydrogenotrophic methanogenesis from the carbon isotope fractionation. As a possible process inducing the inconsistency in hydrogen isotope signatures between experiments and geological samples, we hypothesize that the hydrogen isotope signature of CH4 imprinted at the time of methanogenesis, as in the experiments and natural young methane, may be altered by diagenetic hydrogen isotope exchange

  14. Infrared Absorption of CH_3O/CD_3O Radicals Produced upon Photolysis of CH_3ONO/CD_3ONO in a {p}-H2 Matrix

    Science.gov (United States)

    Lee, Yu-Fang; Chou, Wei-Te; Johnson, Britta; Sibert, Edwin; Lee, Yuan-Pern

    2014-06-01

    The methoxy radical, CH_3O, has attracted much attention because of its important molecular structure and also as a reaction intermediate in combustion and atmospheric chemistry. Previous investigations include laser-induced fluorescence, laser magnetic resonance, and stimulated emission pumping. High-resolution infrared spectrum of jet-cooled CH_3O, produced by laser photolysis of CH_3ONO, in the C-H stretching region 2850-2940 cm-1 has been reported. However, direct infrared absorption spectrum of CH_3O other than the C-H stretching region remains unreported. Irradiation of a {p}-H2 matrix containing CH_3ONO at 3.2 K with UV light produced main features at 1365.4, 1427.5 (21-, 21+), 1041.8 (31-), 1346.8, 1427.5, 1520.9, 1520.9 (51-, 51+, 51-, 51+), and 689.3/694.9, 945.9/951.7, 1233.5, 1235.9 cm-1 (61-, 61+, 61-, 61+); labels 2-6 in parentheses indicate transitions to vibrational states attributable to the umbrella, C-O stretching, CH_2 scissoring, and HCO deformation modes of CH_3O, respectively. These features appeared upon photolysis and diminished after five minutes; formation of CH_2OH was observed as CH_3O decayed. The assignments were based on comparison of observed vibrational wavenumbers with those predicted with the quadratic potential energy force field and quadratic dipole moment expansion calculated with the CCSD(T)/cc-pVTZ method. Jahn-Teller and anharmonic vibrational contributions were included in the full Hamiltonian to estimate the correlation diagram connecting the harmonic eigenvalues to those of the fully coupled problem. Similarly, lines of CD_3O were observed upon UV photolysis of CD_3ONO, but became diminished within five minutes. These observations demonstrates the advantage of diminished cage effect of solid {p}-H2; CH_3O and CD_3O are produced via {in situ} UV photodissociation of CH_3ONO isolated in {p}-H2, but not in Ar or Ne. J.-X. Han, Y. G. Utkin, H.-B. Chen, L. A. Burns and R. F. Curl, J. Chem. Phys., 117, 6538 (2009). J. Nagesh

  15. Feeding of [5,5-2H(2)]-1-desoxy-D-xylulose and [4,4,6,6,6-2H(5)]-mevalolactone to a geosmin-producing Streptomyces sp. and Fossombronia pusilla.

    Science.gov (United States)

    Spiteller, Dieter; Jux, Andreas; Piel, Jörn; Boland, Wilhelm

    2002-12-01

    The biosynthesis of the trisnor sesquiterpenoid geosmin (4,8a-dimethyl-octahydro-naphthalen-4a-ol) (1) was investigated by feeding labeled [5,5-2H(2)]-1-desoxy-D-xylulose (11), [4,4,6,6,6-(2)H(5)]-mevalolactone (7) and [2,2-2H(2)]-mevalolactone (9) to Streptomyces sp. JP95 and the liverwort Fossombronia pusilla. The micro-organism produced geosmin via the 1-desoxy-D-xylulose pathway, whereas the liverwort exclusively utilized mevalolactone for terpenoid biosynthesis. Analysis of the labeling pattern in the resulting isotopomers of geosmin (1) by mass spectroscopy (EI/MS) revealed that geosmin is synthesized in both organisms by cyclization of farnesyl diphosphate to a germacradiene-type intermediate 4. Further transformations en route to geosmin (1) involve an oxidative dealkylation of an i-propyl substituent, 1,2-reduction of a resulting conjugated diene, and bicyclization of a germacatriene intermediate 13. The transformations largely resemble the biosynthesis of dehydrogeosmin (2) in cactus flowers but differ with respect to the regioselectivity of the side chain dealkylation and 1,2-reduction

  16. Endogenous Production of H2S in the Gastrointestinal Tract: Still in Search of a Physiologic Function

    Science.gov (United States)

    Linden, David R.; Levitt, Michael D.; Farrugia, Gianrico

    2010-01-01

    Abstract Hydrogen sulfide (H2S) has long been associated with the gastrointestinal tract, especially the bacteria-derived H2S present in flatus. Along with evidence from other organ systems, the finding that gastrointestinal tissues are capable of endogenous production of H2S has led to the hypothesis that H2S is an endogenous gaseous signaling molecule. In this review, the criteria of gasotransmitters are reexamined, and evidence from the literature regarding H2S as a gaseous signaling molecule is discussed. H2S is produced enzymatically by gastrointestinal tissues, but evidence is lacking on whether H2S production is regulated. H2S causes well-defined physiologic effects in gastrointestinal tissues, but evidence for a receptor for H2S is lacking. H2S is inactivated through enzymatic oxidation, but evidence is lacking on whether manipulating H2S oxidation alters endogenous cell signaling. Remaining questions regarding the role of H2S as a gaseous signaling molecule in the gastrointestinal tract suggest that H2S currently remains a molecule in search of a physiologic function. Antioxid. Redox Signal. 12, 1135–1146. PMID:19769466

  17. Acid pre-treatment of sewage anaerobic sludge to increase hydrogen producing bacteria HPB: effectiveness and reproducibility.

    Science.gov (United States)

    Tommasi, T; Sassi, G; Ruggeri, B

    2008-01-01

    The present study is aimed to test the effectiveness and the reproducibility of the acid pre-treatment of sewage sludge to suppress the methanogenic bacteria activity, in order to increase the hydrogen forming bacteria activity, mainly Clostridium species. The treated sludge has been tested on glucose reach medium under mesophilic conditions (35 degrees C), in batch mode to quantify the biological fermentative hydrogen production. In the whole series of experiments, the main components of biogas are hydrogen (52-60%) and carbon dioxide (40-48%); no methane and hydrogen sulphide were present in it. The rate of biogas production reached a maximum of 75 ml/lh. An overall mean hydrogen conversion efficiency was 11.20% on the assumption of maximum of 3 mol H2/mol glucose. Clostridium spp. multiplied ten times after 10 h of fermentation and over that thousand times at the end of fermentation.

  18. Experimental Research on Hair Produce Wastewater Treatment by Coagulation-Flocculation and H2O2/UV Oxidation Technique%絮凝沉淀-H2O2/UV体系处理发制品废水的研究

    Institute of Scientific and Technical Information of China (English)

    侯海军; 胡立阁; 李成尊; 单宝田; 马根之; 黄立英

    2001-01-01

    研究了发制品废水经絮凝沉淀-H2O2/UV体系处理的可行性.结果表明,废水经处理后,COD去除率可达90%以上,色度去除率达100%.探讨了投药量、反应pH、反应时间等因素对COD去除率的影响,并比较了H2O2/Fe2+、H2O2/UV、H2O2/Fe2+/UV三种体系的处理效果.

  19. Infrared absorption of CH3OSO and CD3OSO radicals produced upon photolysis of CH3OS(O)Cl and CD3OS(O)Cl in p-H2 matrices

    Science.gov (United States)

    Lee, Yu-Fang; Kong, Lin-Jun; Lee, Yuan-Pern

    2012-03-01

    Irradiation at 239 ± 20 nm of a p-H2 matrix containing methoxysulfinyl chloride, CH3OS(O)Cl, at 3.2 K with filtered light from a medium-pressure mercury lamp produced infrared (IR) absorption lines at 3028.4 (attributable to ν1, CH2 antisymmetric stretching), 2999.5 (ν2, CH3 antisymmetric stretching), 2950.4 (ν3, CH3 symmetric stretching), 1465.2 (ν4, CH2 scissoring), 1452.0 (ν5, CH3 deformation), 1417.8 (ν6, CH3 umbrella), 1165.2 (ν7, CH3 wagging), 1152.1 (ν8, S=O stretching mixed with CH3 rocking), 1147.8 (ν9, S=O stretching mixed with CH3 wagging), 989.7 (ν10, C-O stretching), and 714.5 cm-1 (ν11, S-O stretching) modes of syn-CH3OSO. When CD3OS(O)Cl in a p-H2 matrix was used, lines at 2275.9 (ν1), 2251.9 (ν2), 2083.3 (ν3), 1070.3 (ν4), 1056.0 (ν5), 1085.5 (ν6), 1159.7 (ν7), 920.1 (ν8), 889.0 (ν9), 976.9 (ν10), and 688.9 (ν11) cm-1 appeared and are assigned to syn-CD3OSO; the mode numbers correspond to those used for syn-CH3OSO. The assignments are based on the photolytic behavior and a comparison of observed vibrational wavenumbers, infrared intensities, and deuterium isotopic shifts with those predicted with the B3P86/aug-cc-pVTZ method. Our results extend the previously reported four transient IR absorption bands of gaseous syn-CH3OSO near 2991, 2956, 1152, and 994 cm-1 to 11 lines, including those associated with C-O, O-S, and S=O stretching modes. Vibrational wavenumbers of syn-CD3OSO are new. These results demonstrate the advantage of a diminished cage effect of solid p-H2 such that the Cl atom, produced via UV photodissociation of CH3OS(O)Cl in situ, might escape from the original cage to yield isolated CH3OSO radicals.

  20. Evaluation of the Rapidec Carba NP Test Kit for Detection of Carbapenemase-Producing Gram-Negative Bacteria

    Science.gov (United States)

    Garg, Jaya; Upadhyay, G. C.; Agarwal, Anurag; Bhattacharjee, Amitabha

    2015-01-01

    Recently, bioMérieux, France, introduced the Rapidec Carba NP test kit for rapid detection of carbapenemase-producing Gram-negative bacteria. This kit was evaluated in this study, and we report sensitivity, specificity, and positive and negative predictive values of 92.6%, 96.2%, 95.83%, and 92.6%, respectively. The test was easy to perform and interpret and relatively inexpensive ($5/Rs 300 per test) and provides a practical solution for early detection of carbapenemase-producing, multidrug-resistant Gram-negative bacteria. PMID:26416868

  1. Isolation and characterization of bacteriophages specific to hydrogen-sulfide-producing bacteria.

    Science.gov (United States)

    Gong, Chao; Heringa, Spencer; Singh, Randhir; Kim, Jinkyung; Jiang, Xiuping

    2013-01-01

    The objectives of this study were to isolate and characterize bacteriophages specific to hydrogen-sulfide-producing bacteria (SPB) from raw animal materials, and to develop a SPB-specific bacteriophage cocktail for rendering application. Meat, chicken offal, and feather samples collected from local supermarkets and rendering processing plants were used to isolate SPB (n = 142). Bacteriophages (n = 52) specific to SPB were isolated and purified from the above samples using 18 of those isolated SPB strains as hosts. The host ranges of bacteriophages against 5 selected SPB strains (Escherichia coli, Citrobacter freundii, and Hafnia alvei) were determined. Electron microscopy observation of 9 phages selected for the phage cocktail revealed that 6 phages belonged to the family of Siphoviridae and 3 belonged to the Myoviridae family. Restriction enzyme digestion analysis with endonuclease DraI detected 6 distinguished patterns among the 9 phages. Phage treatment prevented the growth of SPB for up to 10 h with multiplicity of infection ratios of 1, 10, 100, and 1000 in tryptic soy broth at 30 °C, and extended the lag phase of SPB growth for 2 h at 22 °C with multiplicities of infection of 10, 100, and 1000. These results suggest that the selected bacteriophage cocktail has a high potential for phage application to control SPB in raw animal materials destined for the rendering process.

  2. Restricted distribution of the butyrate kinase pathway among butyrate-producing bacteria from the human colon.

    Science.gov (United States)

    Louis, Petra; Duncan, Sylvia H; McCrae, Sheila I; Millar, Jacqueline; Jackson, Michelle S; Flint, Harry J

    2004-04-01

    The final steps in butyrate synthesis by anaerobic bacteria can occur via butyrate kinase and phosphotransbutyrylase or via butyryl-coenzyme A (CoA):acetate CoA-transferase. Degenerate PCR and enzymatic assays were used to assess the presence of butyrate kinase among 38 anaerobic butyrate-producing bacterial isolates from human feces that represent three different clostridial clusters (IV, XIVa, and XVI). Only four strains were found to possess detectable butyrate kinase activity. These were also the only strains to give PCR products (verifiable by sequencing) with degenerate primer pairs designed within the butyrate kinase gene or between the linked butyrate kinase/phosphotransbutyrylase genes. Further analysis of the butyrate kinase/phosphotransbutyrylase genes of one isolate, L2-50, revealed similar organization to that described previously from different groups of clostridia, along with differences in flanking sequences and phylogenetic relationships. Butyryl-CoA:acetate CoA-transferase activity was detected in all 38 strains examined, suggesting that it, rather than butyrate kinase, provides the dominant route for butyrate formation in the human colonic ecosystem that contains a constantly high concentration of acetate.

  3. Screening for Glucosyltransferase gene (gtf from exopolysaccahride producing lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Donna M. Ariestanti

    2008-04-01

    Full Text Available Glucosyltransferase (GTF is an enzyme involved in exopolysaccharide (EPS polymer synthesis in microbes. One example of EPS that has been used in pharmaceutical and medical application is dextran. Dextran has been used in conjugated-drug delivery system as matrix. As a group of microbes producing EPS, lactic acid bacteria (LAB have been well reported carrying sucrase genes glucosyltransferase (gtf, as well as fructosyltransferases (ftf. In an attempt to search for novel gtf genes as the aim of this study, LAB collection isolated from local sources yielded from previous study were screened performing PCR using degenerate primers DegFor and DegRev. An approximately 660 base pairs (bp amplicons were obtained by using genomic DNAs of those LAB isolates as templates with conserved region of gtf genes catalytic domain as target. Two out of 20 LAB strains were yielded no amplicon as observed on agarose gel, while one strain exhibited non-specific amplicon DNA bands with sizes other than 660 bp. The two negative ones were isolated from soil obtained from dairy product waste field and from waste of soy sauce from previous study, while the latter was isolated from waste of soy sauce.

  4. [The study of mycolytic properties of aerobic spore-forming bacteria producing extracellular chitinases].

    Science.gov (United States)

    Aktuganov, G E; Melent'ev, A I; Galimzianova, N F; Shirokov, A V

    2008-01-01

    The mycolytic activity of 27 strains of antagonistic bacilli belonging to two taxonomic groups (18 strains of Bacillus subtilis and 9 strains of Paenibacillus ehimensis) capable of induced synthesis of chitinolytic enzymes was studied. Most of the B. subtilis strains neither displayed visible mycolytic effects on the phytopathogenic fungus Bipolaris sorokiniana in vitro, nor produced chitinases in the presence of an auto-claved mycelium. On the contrary, P. ehimensis strains grown under conditions favorable for induction of chitinases and other hydrolases exhibited a pronounced lytic effect on B. sorokiniana and actively grew by utilizing mycelium as the sole source of carbon and nitrogen. Comparison of the mycolytic activities of extracellular hydrolases in the studied strains demonstrated low correlation between chitinase production and the ability of the strains to degrade the cell walls of B. sorokiniana. Characterization of enzyme profiles in the studied strains revealed that beta-1,3-glucanase was a more significant factor than chitinase for determining the mycolytic potential of bacteria and their ability to utilize the mycelium of phytopathogenic fungi as a growth substrate.

  5. Rapid Detection of Pathogenic Bacteria from Fresh Produce by Filtration and Surface-Enhanced Raman Spectroscopy

    Science.gov (United States)

    Wu, Xiaomeng; Han, Caiqin; Chen, Jing; Huang, Yao-Wen; Zhao, Yiping

    2016-04-01

    The detection of Salmonella Poona from cantaloupe cubes and E. coli O157:H7 from lettuce has been explored by using a filtration method and surface-enhanced Raman spectroscopy (SERS) based on vancomycin-functionalized silver nanorod array substrates. It is found that with a two-step filtration process, the limit of detection (LOD) of Salmonella Poona from cantaloupe cubes can be as low as 100 CFU/mL in less than 4 h, whereas the chlorophyll in the lettuce causes severe SERS spectral interference. To improve the LOD of lettuce, a three-step filtration method with a hydrophobic filter is proposed. The hydrophobic filter can effectively eliminate the interferences from chlorophyll and achieve a LOD of 1000 CFU/mL detection of E. coli O157:H7 from lettuce samples within 5 h. With the low LODs and rapid detection time, the SERS biosensing platform has demonstrated its potential as a rapid, simple, and inexpensive means for pathogenic bacteria detection from fresh produce.

  6. Hydrogen Production with High Evolution Rate and High Yield by Immobilized Cells of Hydrogen-producing Bacteria Strain B49 in a Column Reactor

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    To improve the hydrogen evolution rate in continuous hydrogen production of a novel fermentative hydrogen-producing bacteria strain B49 (AF481148 in EMBL), 4 % immobilized cells by polyvinyl alcohol-boric acid method, with the addition of a small amount of calcium alginate in a column reactor obtain hydrogen yield of 2.31 mol H2/mol glucose and hydrogen evolution rate of 1435.4 ml/L culture*h respectively at medium retention time of 2.0 h with a medium containing 10g glucose/L. Moreover, as the cell density in gel beads is increased to 8%, hydrogen yield and hydrogen evolution rate for 10g glucose/L are 2.34 mol H2/mol glucose and 2912.4 ml/L culture*h respectively at medium retention time of 1.0 h, and for molasses wastewater COD of 7505.9 mg/L hydrogen production potential of 205.6 ml/g COD and hydrogen evolution rate of 2057.7 ml/L culture*h at hydraulic retention time of 0.75 h are observed. In the continuous culture pH value keeps around 3.9 by self-regulating.

  7. Are Bacteria the Major Producers of Extracellular Glycolytic Enzymes in Aquatic Environments?

    Science.gov (United States)

    Vrba, Jaroslav; Callieri, Cristiana; Bittl, Thomas; Imek, Karel; Bertoni, Roberto; Filandr, Pavel; Hartman, Petr; Hejzlar, Josef; Macek, Miroslav; Nedoma, Jií

    2004-01-01

    In aquatic microbial ecology, it has been considered that most extracellular enzymes except phosphatases are of bacterial origin. We tested this paradigm by evaluating the relationship between bacterial cell number and the activity of three glycolytic enzymes from 17 fresh waters and also from a laboratory experiment. Our large sets of pooled data do not seem to support such a simple explanation, because we found only a weak correlation of bacterial number with activity of -glucosidase (rs = 0.63), -glucosidase (rs = 0.45), and -N-acetylhexosaminidase (rs = 0.44). We also tested relations of the enzymatic activities to potential sources of natural substrates: dissolved organic carbon (DOC) and phytoplankton (as chlorophyll a). Their correlations with the enzymatic activities tested were very weak or insignificant. On the other hand, we found evidence for distinct producers of extracellular enzymes by analysing enzyme kinetics. The kinetics usually did not follow the simple Michaelis-Menten model but a more complex one, indicating a mixture of two enzymes with distinct affinity to a substrate. In combination with size fractionation, we could sometimes even distinguish three or more different enzymes. During diatom blooms, the diatom biomass tightly correlated with β-N-acetylhexosaminidase activity (>4 μm fraction). We also documented very tight relationships between activity of both glucosidases and dry weight of Daphnia longispina (rs = 1.0 and 0.60 for α- and β-glucosidases, respectively) in an alpine clear-water lake. Our data and evidence from other studies indicate that extracellular glycosidic activities in aquatic ecosystems cannot generally be assigned only to bacteria. Also invertebrate animals and other eukaryotes (fungi, diatoms, protozoa etc.) should be considered as potentially very important enzyme producers. (

  8. 生物质焦油模拟物重整制取富氢气体实验研究%Experimental research on model compound reforming of biomass tar to produce H2-rich gas

    Institute of Scientific and Technical Information of China (English)

    谢玉荣; 沈来宏; 肖军; 王俊; 常连成

    2011-01-01

    The tar model compound (benzene) reforming to produce hydrogen-rich gas was investigated in a fluidized bed, where the steam acts as the gasification medium. The influences of operating parameters on producing hydrogen-rich gas were fully investigated by changing the reactor temperature, the ratio of steam mass to tars mass (S/T) and the bed height; in addition, the effects of various bed materials (catalysts) on the reforming reaction are also focused on in this paper. The reactor temperature was varied from 780 '℃to 900 ℃ , S/T from 3.0 to 6.0, and the bed height from 5.0 cm to 20.0 cm. The experimental results demonstrate that the optimum operating parameters for producing hydrogen-rich gas are the reactor temperature of 860 ℃ ~ 900 ℃, S/T of 5.0 and the bed height of 15. 0 cm -20.0 cm. Under the condition of optimum operation, the synthesized alkaline earth metal-based catalyst ( 20CaAl) displays a better catalysis than natural ores ( dolomite and limestone). And the modified catalyst SCaFeNiAl based on 20CaAl exhibits a higher catalytic activity with the activation energy of 58. 87 kJ/mol and pre-exponential factor of 1. 36xlO7 h-1. With SCaFeNiAl, the H2 content of 67.28% , the H2 yield of 303. 50 (g/kg-tar) , the tar conversion ratio of 95. 93% and the total gas yield of 5.05 (mVkg-tar) are obtained.%以流化床作为反应器,进行生物质焦油模拟物(苯)催化重整制取富氢气体的实验研究,主要探究实验温度(780℃~900℃)、水蒸气/焦油模拟物质量比S/T (3.0~6.0)、床高(5.0cm~20.0cm)和床料(催化剂)对焦油模拟物重整制取富氢气体过程的影响.实验结果表明,焦油模拟物重整制取富氢气体的理想操作工况分别是温度为860℃~900℃,S/T 值为5.0,床层高度为15.0cm~20.0cm;通过比较,在上述理想操作条件下,合成的碱土金属催化剂(20CaAl)具有较好的催化活性,而其改性后的SCaFeNiAl催化剂具有更好的活性.在SCaFeNiAl作用

  9. Melatonin-producing endophytic bacteria from grapevine roots promote the abiotic stress-induced production of endogenous melatonin in their hosts

    Directory of Open Access Journals (Sweden)

    Jian Jiao

    2016-09-01

    Full Text Available Endophytes form symbiotic relationships with plants and constitute an important source of phytohormones and bioactive secondary metabolites for their hosts. To date, most studies of endophytes have focused on the influence of these microorganisms on plant growth and physiology and their role in plant defenses against biotic and abiotic stressors; however, to the best of our knowledge, the ability of endophytes to produce melatonin has not been reported. In the present study, we isolated and identified root-dwelling bacteria from three grapevine varieties and found that, when cultured under laboratory conditions, some of the bacteria strains secreted melatonin and tryptophan-ethyl ester. The endophytic bacterium Bacillus amyloliquefaciens SB-9 exhibited the highest level of in vitro melatonin secretion and also produced three intermediates of the melatonin biosynthesis pathway: 5-hydroxytryptophan, serotonin, and N-acetylserotonin. After B. amyloliquefaciens SB-9 colonization, the plantlets exhibited increased plant growth. Additionally, we found that, in grapevine plantlets exposed to salt or drought stress, colonization by B. amyloliquefaciens SB-9 increased the upregulation of melatonin synthesis, as well as that of its intermediates, but reduced the upregulation of grapevine tryptophan decaboxylase genes (VvTDCs and a serotonin N-acetyltransferase gene (VvSNAT transcription, when compared to the un-inoculated control. Colonization by B. amyloliquefaciens SB-9 was also able to counteract the adverse effects of salt- and drought-induced stress by reducing the production of malondialdehyde and reactive oxygen species (H2O2 and O2− in roots. Therefore, our findings demonstrate the occurrence of melatonin biosynthesis in endophytic bacteria and provide evidence for a novel form of communication between beneficial endophytes and host plants via melatonin.

  10. Isotopologue signatures of nitrous oxide produced by nitrate-ammonifying bacteria isolated from soil

    Science.gov (United States)

    Behrendt, Undine; Well, Reinhard; Giesemann, Anette; Ulrich, Andreas; Augustin, Jürgen

    2015-04-01

    Agricultural soils are the largest single source of anthropogenic N2O to the atmosphere, primarily driven by microbiological processes such as denitrification and dissimilatory nitrate reduction to ammonium (DNRA). Both processes occur under similar conditions of low oxygen concentration and therefore, source partitioning of emitted N2O is difficult. Understanding what controls the dynamics and reaction equilibrium of denitrification and DNRA is important and may allow the development of more effective mitigation strategies. 15N site preference (SP), i.e. the difference between 15N of the central and peripheral N-position of the asymmetric N2O molecule, differs depending on processes involved in N2O formation. Hence investigation of the isotopomer ratios of formed N2O potentially presents a reliable mean to identify its source. In this study, bacterial isolates obtained from organic soils were screened for their ability to reduce nitrate/nitrite to ammonium and to release N2O to the atmosphere. Taxonomic characterisation of the strains revealed that N2O formation was only detected in ammonifying strains affiliated to several genera of the family Enterobacteriaceae and strains belonging to the genus Bacillus and Paenibacillus. Sampling of N2O was conducted by incubation of strains under oxic and anoxic conditions. Investigation of the 15N site preference showed SP values in the range of 39 to 57 o . Incubation conditions had no influence on the SP. The lowest values were achieved by a strain of the species Escherichia coli which was included in this study as a DNRA reference bacterium harbouring the NrfA gene that is coding the nitrite reductase, associated with respiratory nitrite ammonification. Soil isolates showed SP-values higher than 40 o . Comparison of these results with SP-values of N2O produced by denitrifying bacteria in pure cultures (-5 to 0 o )^[1, 2]revealedsignificantdifferences.Incontrast,N_2OproducedbydenitrifyingfungidisplayedSP - valuesinarangeof

  11. Novel touchdown-PCR method for the detection of putrescine producing gram-negative bacteria in food products.

    Science.gov (United States)

    Wunderlichová, Leona; Buňková, Leona; Koutný, Marek; Valenta, Tomáš; Buňka, František

    2013-06-01

    Formation of biogenic amines may occur in food due to metabolic activities of contaminating Gram-negative bacteria. Putrescine is assumed to be the major biogenic amine associated with microbial food spoilage. Gram-negative bacteria can form putrescine by three metabolic pathways that can include eight different enzymes. The objective of this study was to design new sets of primers able to detect all important enzymes involved in the production of putrescine by Gram-negative bacteria. Seven new sets of consensual primers based on gene sequences of different bacteria were designed and used for detection of the speA, adiA, adi, speB, aguA, speC, and speF genes. A newly developed touchdown polymerase chain reaction (PCR) method using these primers was successfully applied on several putrescine-producers. Selected PCR products were sequenced and high similarity of their sequences (99-91%) with known sequences of the corresponding genes confirmed high specificity of the developed sets of primers. Furthermore, all the investigated bacteria produced both putrescine and agmatine, an intermediate of putrescine production, which was confirmed by chemical analysis. The developed new touchdown PCR method could easily be used to detect potential foodborne Gram-negative producers of putrescine. The newly developed sets of primers could also be useful in further research on putrescine metabolism in contaminating microbiota.

  12. Production of two bacteriocins in various growth conditions produced by gram-positive bacteria isolated from chicken cecum.

    Science.gov (United States)

    Wang, Qiuju; Cui, Yizhe; Wang, Wenmei; Xu, Jili; Xu, Li

    2012-01-01

    Lactobacillus plantarum CLP29 and Enterococcus faecium CLE34 isolated from the cecal contents of young broiler chicks were identified based on physiological and biochemical characteristics, and identification was confirmed by 16S rRNA sequencing. Both bacteria showed a broad range of inhibitory action against bacteria such as Salmonella and Escherichia coli and produced two peptides, plantaricin CLP29 and enterocin CLE34. Treatment with proteinase K, trypase, or benase resulted in the loss of activity of the two peptides, confirming their proteinaceous nature. The highest activity levels for both bacteria were recorded in de Man - Rogosa - Sharpe agar at pH 5.0, 6.0, and 7.0, at 37 °C. Carbon and nitrogen sources affected the antibacterial activities of the two bacteriocins in different combinations, which suggested that the antibacterial abilities of different bacteriocins produced in nutrient sources were various.

  13. Appropriateness of empirical treatment and outcome in bacteremia caused by extended-spectrum-β-lactamase-producing bacteria

    NARCIS (Netherlands)

    F.N.J. Frakking (Florine N.); W.C. Rottier (Wouter); J.W. Dorigo-Zetsma; J.M. van Hattem (Jarne); B.C. van Hees (Babette); J.A.J.W. Kluytmans (Jan); S.P.M. Lutgens (Suzanne P.); J.M. Prins (Jan); S.F. Thijsen (Steven); A. Verbon (Annelies); B.J.M. Vlaminckx (Bart J.); J.W.C. Stuart (James W. Cohen); M.A. Leverstein-Van Hall (Maurine); M.J.M. Bonten (Marc)

    2013-01-01

    textabstractWe studied clinical characteristics, appropriateness of initial antibiotic treatment, and other factors associated with day 30 mortality in patients with bacteremia caused by extended-spectrum-β-lactamase (ESBL)-producing bacteria in eight Dutch hospitals. Retrospectively, information wa

  14. Dietary fibres modulate the composition and activity of butyrate-producing bacteria in the large intestine of suckling piglets

    NARCIS (Netherlands)

    Mu, Chunlong; Zhang, Lingli; He, Xiangyu; Smidt, Hauke; Zhu, Weiyun

    2017-01-01

    Dietary fibres have been shown to affect early-life microbiota colonization in the large intestine of suckling piglets, however, much less is known as to whether they also modulate the composition and activity of butyrate-producing bacteria. Here, we investigated the effect of dietary fibres on the

  15. Differential sensitivity of polyhydroxyalkanoate producing bacteria to fermentation inhibitors and comparison of polyhydroxybutyrate production from Burkholderia cepacia and Pseudomonas pseudoflava

    Science.gov (United States)

    Diane Dietrich; Barbara Illman; Casey Crooks

    2013-01-01

    The aim of this study is determine the relative sensitivity of a panel of seven polyhydroxyalkanoate producing bacteria to a panel of seven lignocellulosic-derived fermentation inhibitors representing aliphatic acids, furans and phenolics. A further aim was to measure the polyhydroxybutyrate production of select organisms on lignocellulosic-derived monosaccharides...

  16. Predicting carriage with extended-spectrum beta-lactamase-producing bacteria at hospital admission : A cross-sectional study

    NARCIS (Netherlands)

    Platteel, T. N.; Leverstein-van Hall, M. A.; Cohen Stuart, J. W.; Thijsen, S. F T; Mascini, E. M.; van Hees, B. C.; Scharringa, J.; Fluit, A. C.; Bonten, M. J M

    2015-01-01

    The prevalence of patients colonized with extended-spectrum beta-lactamase (ESBL)-producing bacteria increases, especially in long-term-care facilities (LTCFs). Identification of ESBL carriers at hospital admission is relevant for infection control measures and antibiotic therapy for nosocomial infe

  17. Appropriateness of empirical treatment and outcome in bacteremia caused by extended-spectrum-β-lactamase-producing bacteria

    NARCIS (Netherlands)

    F.N.J. Frakking (Florine N.); W.C. Rottier (Wouter); J.W. Dorigo-Zetsma; J.M. van Hattem (Jarne); B.C. van Hees (Babette); J.A.J.W. Kluytmans (Jan); S.P.M. Lutgens (Suzanne P.); J.M. Prins (Jan); S.F. Thijsen (Steven); A. Verbon (Annelies); B.J.M. Vlaminckx (Bart J.); J.W.C. Stuart (James W. Cohen); M.A. Leverstein-Van Hall (Maurine); M.J.M. Bonten (Marc)

    2013-01-01

    textabstractWe studied clinical characteristics, appropriateness of initial antibiotic treatment, and other factors associated with day 30 mortality in patients with bacteremia caused by extended-spectrum-β-lactamase (ESBL)-producing bacteria in eight Dutch hospitals. Retrospectively, information wa

  18. [Beta-lactamase producing bacteria in the pharyngeal flora of patients with acute pharyngitis].

    Science.gov (United States)

    Romero-Vivas, J; Betriu, C; Sánchez, M L; Herranz, B; Picazo, J J

    1995-01-01

    Production of beta-lactamase by normal pharyngeal flora could account for penicillin treatment failure in patients with acute streptococcal pharyngitis. The aim of the present investigation was to study the beta-lactamase-producing bacteria (BLPB) in 58 patients with acute pharyngitis, and to investigate the impact of two antibiotics, amoxycillin vs amoxycillin/clavulanic acid in the pharyngeal microflora. Rapid antigen detection tests for S. pyogenes and standard microbiologic cultures were performed on simultaneously obtained throat swabs from each enrolled patient. Patients with group A streptococcal pharyngitis (GASP) were randomized in two groups: patients treated with 10 days of oral amoxycillin (group I), and patients treated with 10 days of oral amoxicyllin/clavulanic acid (group II). Patients without GASP and without antibiotic treatment were considered as controls (group III). Cultures were repeated 15 days following the first culture. All of them were processed for aerobic and anaerobic organisms. S. pyogenes was recovered in 25 patients (43.1%) and BLPB were isolated in 64% of the treated patients and in 78% of the non-treated control patients. We observed that the number of patients harboring BLPB did not change significantly in the untreated control group. After treatment we detected a similar increase in the number of patients harboring BLPB in groups I and II. In the present study BLPB were found in more than 70% of the patients and the failure rate was less than 10%. The results of this study indicate that production of beta-lactamase by pharyngeal organisms does not fully explain the failures of penicillin therapy for acute streptococcal pharyngitis.

  19. Faecal carriage of extended-spectrum b-lactamase-producing and AMpC b-lactamase-producing bacteria among Danish army recruits

    DEFF Research Database (Denmark)

    Hammerum, A.M; Lester, C.H; Jakobsen, L

    2011-01-01

    During May and June 2008, 84 Danish army recruits were tested for faecal carriage of extended-spectrum b-lactamase (ESBL)- producing and AmpC b-lactamase-producing bacteria. Three ESBL-producing (CTX-M-14a) Escherichia coli isolates, two AmpC-producing (CMY-2) E. coli isolates and one Amp......C-producing (CMY-34) Citrobacter freundii isolate were detected. Two of the CTX-M-14a E. coli isolates had similar pulsed-field gel electrophoresis and multilocus sequence typing profiles, indicating the same origin or transmission between the two army recruits. The blaCTX-M-14a genes were transferable to an E...

  20. In vitro Characterization of Bacteriocin Produced by Lactic Acid Bacteria Isolated from Nem Chua, a Traditional Vietnamese Fermented Pork.

    Science.gov (United States)

    Pilasombut, Komkhae; Rumjuankiat, Kittaporn; Ngamyeesoon, Nualphan; Duy, Le Nguyen Doan

    2015-01-01

    The aim of this study was to screen and In vitro characterize the properties of bacteriocin produced by lactic acid bacteria isolated from Vietnamese fermented pork (Nem chua). One hundred and fifty LAB were isolated from ten samples of Nem chua and screened for bacteriocin-producing lactic acid bacteria. Antimicrobial activity of bacteriocin was carried out by spot on lawn method against both gram positive and gram negative bacteria. One isolate, assigned as KL-1, produced bacteriocin and showed inhibitory activity against Lactobacillus sakei, Leuconostoc mesenteroides and Enterococcus faecalis. To characterize the bacteriocin-producing strain, optimum temperature, incubation period for maximum bacteriocin production and identification of bacteriocin-producing strain were determined. It was found that the optimum cultivation temperature of the strain to produce the maximum bacteriocin activity (12,800 AU/mL) was obtained at 30℃. Meanwhile, bacteriocin production at 6,400 AU/mL was found when culturing the strain at 37℃ and 42℃. The isolate KL-1 was identified as L. plantarum. Antimicrobial activity of cell-free supernatant was completely inhibited by proteolytic enzyme of trypsin, alpha-chymotrypsin and proteinase K. Bacteriocin activity was stable at high temperature up to 100℃ for 10 min and at 4℃ storage for 2 d. However, the longer heating at 100℃ and 4℃ storage, its activity was reduced.

  1. Bacillus spp. produce antibacterial activities against lactic acid bacteria that contaminate fuel ethanol plants

    Science.gov (United States)

    Lactic acid bacteria (LAB) frequently contaminate commercial fuel ethanol fermentations, reducing yields and decreasing profitability of biofuel production. Microorganisms from environmental sources in different geographic regions of Thailand were tested for antibacterial activity against LAB. Fou...

  2. Screening on DHA-producing Antarctic bacteria N- 6 and its cultural conditions

    Institute of Scientific and Technical Information of China (English)

    Zhang Botao; Miao Jin-lai; Hui Hanxing; Wang Qing

    2006-01-01

    In Antarctic, the geography and climate differs from those in other places,and the bacteria there have adapted well to the environment there. Two hundred strains of bacteria were isolated from the sea ice in Antarctica. The bacteria were screened for DHA by means of GC, with fish oil as the standard. Seven strains containing DHA or EPA were obtained, among which the strain of No. N-6 was outstanding. And the component of DHA was identified by GC-MS. The relative content of DHA in N-6 was 8.72%, and total lipids in dry bacteria was 22.54%. The effects of some factors, including temperature, salinity and pH value, on the growth and DHAcontent of strain N-6 were studied. The results show that the DHA-content is relatively high when in low temperature and high pH, and the bacterium is psychrophilic, alkalophilic.

  3. Broad-spectrum antifungal-producing lactic acid bacteria and their application in fruit models

    National Research Council Canada - National Science Library

    Crowley, Sarah; Mahony, Jennifer; van Sinderen, Douwe

    2013-01-01

    A large-scale screen of some 7,000 presumptive lactic acid bacteria (LAB), isolated from animal, human, or plant origin, identified 1,149 isolates with inhibitory activity against the food-spoilage mould Penicillium expansum...

  4. Emergence of ciprofloxacin-resistant extended-spectrum β-lactamase-producing enteric bacteria in hospital wastewater and clinical sources.

    Science.gov (United States)

    Maheshwari, Meenu; Yaser, Nawar Hadi; Naz, Suraiya; Fatima, Mansha; Ahmad, Iqbal

    2016-06-01

    This study aimed to evaluate the incidence of ciprofloxacin-resistant extended-spectrum β-lactamase (ESBL)-producing enteric bacteria in hospital wastewater and clinical sources. Enteric bacteria, mainly Escherichia coli, were isolated from clinical sources (urinary tract and gastrointestinal tract infections; 80 isolates) and hospital wastewater (103 isolates). The antibiotic resistance profile and ESBL production of the isolates were investigated by disc diffusion assay and combined disc diffusion test, respectively. Plasmid profiling was performed by agarose gel electrophoresis, and elimination of resistance markers was performed by a plasmid curing experiment. Antibiotic susceptibility testing revealed a high incidence of β-lactam resistance, being highest to ampicillin (88.0%) followed by amoxicillin, ceftriaxone, cefpodoxime, cefotaxime, aztreonam, cefepime and ceftazidime. Among the non-β-lactam antibiotics, the highest resistance was recorded to nalidixic acid (85.7%). Moreover, 50.8% of enteric bacteria showed resistance to ciprofloxacin. Among 183 total enteric bacteria, 150 (82.0%) exhibited multidrug resistance. ESBL production was detected in 78 isolates (42.6%). A significantly higher incidence of ciprofloxacin resistance was observed among ESBL-producing enteric bacteria both in clinical (P=0.0015) and environmental isolates (P=0.012), clearly demonstrating a close association between ESBL production and ciprofloxacin resistance. Plasmid profiling of selected ESBL-positive strains indicated the presence of one or more plasmids of varying sizes. Plasmid curing resulted in loss of ciprofloxacin and cefotaxime resistance markers simultaneously from selected ESBL-positive isolates, indicating the close relationship of these markers. This study revealed a common occurrence of ciprofloxacin-resistant ESBL-producing enteric bacteria both in hospital wastewater and clinical sources, indicating a potential public health threat.

  5. Detection of Carbapenemase-Producing Bacteria by Using an Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry Method

    Science.gov (United States)

    Verhoeven, Paul O.; Guezzou, Salim; Fonsale, Nathalie; Aubert, Gerald

    2014-01-01

    The emergence of carbapenemase-producing bacteria poses a new challenge in the management of antibiotic therapies for patients. This report describes a new method using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for rapid detection of carbapenemase activity in enterobacteria, Pseudomonas aeruginosa, and Acinetobacter baumannii. In a panel of 78 isolates, including 41 carbapenemase-producing strains, the ULPC-MS/MS assay showed 100% agreement with molecular characterization, whereas six carbapenemase-producing isolates were not detected by the modified Hodge test. PMID:24295978

  6. [Analysis of dynamic characteristics for fermentative hydrogen-producing bacteria community and hydrogen producing capability in CSTR].

    Science.gov (United States)

    Song, Jia-Xiu; Ren, Nan-Qi; Chen, Ying; An, Dong

    2009-07-15

    The start into the types of fermentation was carried out by pH adjustment from 4.2 to 6.0 in CSTR system. The process of transforming of hydrogen production and dynamic community of bacteria were studied. The results showed that with the organic load maintained at (33 +/- 1) kg/(m3 x d), there was no change in 10 d for the type of fermentation, the amount of hydrogen does not reduce in 8 d. After 15 d, the system was transformed from the ethanol-based type into butyric acid type and water alkalinity was from 250 mg/L to 2450 mg/L. The use of fluorescence in situ hybridization (FISH) system was in response to the 3 groups of micro-organisms. It was found that in the process of transforming, Clostridium cluster XI increases and Clostridium cluster I and II decreases. Enterobacteriaceae always existed with no change. The microbial growth must be considered with hydrogen production capability. The average hydrogen production rate reached to 23.6 mol/(kg x d) with Clostridium cluster I and II dominated in fermentation reactor.

  7. Isolation and characterization of bacteriocin-producing lactic acid bacteria from ready-to-eat food products.

    Science.gov (United States)

    Kelly, W J; Asmundson, R V; Huang, C M

    1996-12-01

    Lactic acid bacteria isolated from a range of foods sold in ready-to-eat form were screened for bacteriocin production. Twenty-two bacteriocin-producing cultures were isolated from 14 of the 41 foods sampled. Bacteriocin-producing isolates from meat, fish and dairy products were Lactobacillus and Leuconostoc species typically found associated with these products. Most of these isolates gave only a narrow inhibitory spectrum although two showed activity against Listeria monocytogenes. Fruit and vegetable products gave a broader range of organisms but most of the bacteriocin-producing cultures were found to be strains of Lactococcus. Several lactococci produced a nisin-like activity, and showed a broad inhibitory spectrum against the indicator strains tested. The ease with which bacteriocin-producing strains could be isolated implies that they are already being safely consumed in food, and highlights the potential for using bacteriocin-producing cultures for biopreservation, especially in association with minimally processed products.

  8. Occurrence of indole-3-acetic Acid-producing bacteria on pear trees and their association with fruit russet.

    Science.gov (United States)

    Lindow, S E; Desurmont, C; Elkins, R; McGourty, G; Clark, E; Brandl, M T

    1998-11-01

    ABSTRACT A relatively high percentage of epiphytic bacteria on pear leaf and fruit surfaces had the ability to produce indole-3-acetic acid (IAA) in culture media supplemented with tryptophan. While over 50% of the strains produced at least small amounts of IAA in culture, about 25% of the strains exhibited high IAA production as evidenced by both colorimetric and high-performance liquid chromatography analysis of culture supernatants. A majority of the strains that produced high amounts of IAA were identified as Erwinia herbicola (Pantoea agglomerans), while some strains of Pseudomonas syringae, Pseudomonas viridiflava, Pseudomonas fluorescens, Pseudomonas putida, and Rahnella aquaticus that produced high amounts of IAA also were found on pear. Fruit russeting was significantly increased in 39 out of 46 trials over an 8-year period in which IAA-producing bacteria were applied to trees compared with control trees. A linear relationship was observed between fruit russet severity and the logarithm of the population size of different IAA-producing bacteria on trees in the 30 days after inoculation, when normalized for the amount of IAA produced by each strain in culture. On average, the severity of fruit russet was only about 77% that on control trees when trees were treated at the time of bloom with Pseudomonas fluorescens strain A506, which does not produce IAA. Both total bacterial populations on pear in the 30-day period following full bloom and fruit russet severity varied greatly from year to year and in different commercial orchards over a 10-year period. There was a strong linear correlation between the logarithm of total bacterial population sizes and fruit russet severity.

  9. Screening of Bacteriocin-producing Lactic Acid Bacteria%产细菌素乳酸菌的筛选

    Institute of Scientific and Technical Information of China (English)

    胡欣洁; 刘云; 邓清云

    2012-01-01

    [Objective]To develop a strain of high-efficient bacteriocin with broader antimicrobial spectrum as natural preservative. [ Method] With pickles and yoghurt as raw materials, the bacteria, which could inhibit the indicator bacteria, was screened from the test materials by using MRS selective medium, and whether the bacteria could produce bacteriocin or not was determined by the tests of excluding acid inhibition, hydrogen peroxide inhibition and protease sensitivity. [Result]The screened strain was identified to be lactic acid bacteria, the produced bacteriocin had inhibitive effect against gram-negative and gram-positive bacteria, and it was a strain of lactic acid bacteria with iroad spectrum and the ability of bacteriocin-producing. [Conclusion]The bacteriocin-producing lactic acid bacteria had important roles in inhibiting various pathogens and food decay.%[目的]开发出更加高效、抑菌谱更广、可做天然防腐剂的细菌素.[方法]以泡菜、酸奶为原料,利用MRS选择培养基从试材中筛选出能够抑制指示菌的细菌,通过排除酸抑制作用、过氧化氢抑制作用和蛋白酶敏感性试验证明该菌株是否产生有抑菌作用的细菌素.[结果]筛选得到的菌株经鉴定证明是乳酸菌,其产生的细菌素对革兰氏阴性菌和革兰氏阳性菌都有抑制作用,是一株产广谱细菌素的乳酸菌.[结论]筛选得出的乳酸菌细菌素在抑制各种病原菌和食品腐败等方面具有重要作用.

  10. Effects of interactions of auxin-producing bacteria and bacterial-feeding nematodes on regulation of peanut growths.

    Science.gov (United States)

    Xu, Li; Xu, Wensi; Jiang, Ying; Hu, Feng; Li, Huixin

    2015-01-01

    The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil.

  11. Bioautography-guided isolation of antibacterial compounds of essential oils from Thai spices against histamine-producing bacteria.

    Science.gov (United States)

    Lomarat, Pattamapan; Phanthong, Phanida; Wongsariya, Karn; Chomnawang, Mullika Traidej; Bunyapraphatsara, Nuntavan

    2013-05-01

    The outbreak of histamine fish poisoning has been being an issue in food safety and international trade. The growth of contaminated bacterial species including Morganella morganii which produce histidine decarboxylase causes histamine formation in fish during storage. Histamine, the main toxin, causes mild to severe allergic reaction. At present, there is no well-established solution for histamine fish poisoning. This study was performed to determine the antibacterial activity of essential oils from Thai spices against histamine-producing bacteria. Among the essential oils tested, clove, lemongrass and sweet basil oils were found to possess the antibacterial activity. Clove oil showed the strongest inhibitory activity against Morganella morganii, followed by lemongrass and sweet basil oils. The results indicated that clove, lemongrass and sweet basil oils could be useful for the control of histamine-producing bacteria. The attempt to identify the active components using preparative TLC and GC/MS found eugenol, citral and methyl chavicol as the active components of clove, lemongrass and sweet basil oils, respectively. The information from this study would be useful in the research and development for the control of histamine-producing bacteria in fish or seafood products to reduce the incidence of histamine fish poisoning.

  12. Community spread of extended-spectrum β-lactamase-producing bacteria detected in social insurance hospitals throughout Japan.

    Science.gov (United States)

    Shibasaki, Mayumi; Komatsu, Masaru; Sueyoshi, Noriyuki; Maeda, Misaho; Uchida, Takae; Yonezawa, Hitoshi; Inagaki, Kenji; Omi, Ayako; Matsumoto, Hidenobu; Murotani, Makiko; Iwamoto, Tsukasa; Kodaka, Yoshihiro; Kieda, Hideto; Tokiwa, Manabu; Masuwa, Bunji; Kinoshita, Mari; Saito, Kazuei; Katou, Masahiko

    2016-06-01

    We surveyed the status of community-acquired infections involving four extended-spectrum β-lactamase (ESBL)-producing bacteria (Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis) isolated from clinical specimens from 11 social insurance hospitals in Japan in 2012. These are member hospitals of the Japan Community Healthcare Organization, an independent administrative hospital organization. The isolation rates for E. coli, K. pneumoniae, K. oxytoca, and P. mirabilis were 14.0% (165/1176), 3.3% (16/480), 3.1% (4/130), and 15.9% (17/107), respectively. The CTX-M-9 group, the most frequently detected genotype, was found in 77.0% (127/165) of E. coli and 43.8% (7/16) of K. pneumoniae isolates. Among K. oxytoca isolates, 75% (3/4) were the CTX-M-1 group, and all 17 P. mirabilis strains were the CTX-M-2 group. ESBL-producing bacteria isolation rates in each hospital ranged from 5.8% to 21.5% (median 9.5%), and the proportion of community-acquired infections among ESBL-producing bacteria isolates ranged from 1.6% to 30.8% (median 11.4%) in each hospital. Overall, the rates of ESBL-producing bacterial infection in all community-acquired infections and in all hospital infections were 10.6% (115/1081) and 10.7% (87/812), respectively. The ESBL-producing bacteria are not limited to certain regions or hospitals but are spreading in communities throughout Japan. Copyright © 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  13. Isolation, identification and optimization of ethanol producing bacteria from Saccharomyces-based fermentation process of alcohol industries in Iran

    Directory of Open Access Journals (Sweden)

    Hoda Ebrahimi

    2013-01-01

    Full Text Available Introduction: Due to the vast growth of world population, consumption of a lot of energy, limited energy supply and rising prices of fuel oil in the future, other alternative energy source is essential. Ethanol is renewable and a safe fuel and it is mainly based on microbial fermentation. The purpose of this study was isolation of high ethanol producing bacteria from the fermentation process of alcohol industries and optimization of growth conditions to be introduced to the industries. Materials and methods: The samples that were collected from fermentation tanks of alcohol industries were enriched in ZSM medium. To isolate the ethanol producing bacteria, the enriched culture was transferred on RMA agar. Bacterial growth conditions and their effects on ethanol production were optimized based on pH, growth temperature, agitation, fermentation time, initial substrate concentration and carbon and nitrogen sources. In addition, the morphological, physiological and molecular characterizations were investigated for identification of the isolates.Results: Three bacterial isolates ZYM7, ZYM8 and ZYM9 were isolated from fermentation tank. All isolates were able to produce ethanol 5.00, 7.60 and 4.00 gL-1 after 48 hours, respectively. The results demonstrated that all isolates were able to consume most sugars sources specially pentose carbon xylose. The isolate ZYM7 produced 13.00 gL-1 ethanol by consumption of xylose. The results of morphological and physiological characteristics showed that ZYM7 belonged to Lactobacillus sp. and ZYM8 and ZYM9 belonged to Acetobacter sp. Moreover, 16S rRNA sequencing and phylogenetic analyses exhibited that ZYM7 was similar to Lactobacillus rhamnosus with 99% homology and ZYM8 and ZYM9 were similar to Acetobacter pasteurianus with 99 and 98% homology, respectively.Discussion and conclusion: The results showed that that the isolated bacteria were suitable candidates to produce ethanol from raw material enriched with

  14. Antagonistic activity of antibiotic producing Streptomyces sp. against fish and human pathogenic bacteria

    Directory of Open Access Journals (Sweden)

    Nazmul Hossain

    2014-04-01

    Full Text Available In this study, attempts were made to isolate Streptomyces sp. from soil samples of two different regions of Bangladesh and evaluate their antagonistic activity against fish and human pathogenic bacteria. A total of 10 isolates were identified as Streptomyces sp. based on several morphological, physiological and biochemical tests. Cross streak method was used to observe the antagonistic activity of the Streptomyces sp. isolates against different fish pathogens belonging to the genus Aeromonas, Pseudomonas and Edwardsiella and human clinical isolates belonging to the genus Klebsiella, Salmonella and Streptococcus. Seven Streptomyces sp. isolates showed antagonism against both fish and human pathogenic bacteria. Four isolates viz., N24, N26, N28 and N47 showed broad spectrum of antagonistic activity (80-100% against all genera of fish and human pathogenic bacteria. The isolate N49 exhibited highest spectrum of antagonism against all fish pathogens (90-100% but comparatively lower degree of antagonism against human pathogens (50-60%. Rest of the two isolates (N21 and N23 showed variability in their antagonism. Results showed that broad spectrum antibiotic(s could be developed from the isolates N24, N26, N28 and N47against several human and fish pathogens. The isolate N49 could be a potential source of antibiotic, especially for fish pathogenic bacteria.

  15. Isolation, identification and optimization of ethanol producing bacteria from Saccharomyces-based fermentation process of alcohol industries in Iran

    OpenAIRE

    Hoda Ebrahimi; Mojtaba Mohseni

    2013-01-01

    Introduction: Due to the vast growth of world population, consumption of a lot of energy, limited energy supply and rising prices of fuel oil in the future, other alternative energy source is essential. Ethanol is renewable and a safe fuel and it is mainly based on microbial fermentation. The purpose of this study was isolation of high ethanol producing bacteria from the fermentation process of alcohol industries and optimization of growth conditions to be introduced to the industries. Materi...

  16. The effects of metabolite molecules produced by drinking water-isolated bacteria on their single and multispecies biofilms.

    Science.gov (United States)

    Simões, Lúcia Chaves; Simões, Manuel; Vieira, Maria João

    2011-08-01

    The elucidation of the mechanisms by which diverse species survive and interact in drinking water (DW) biofilm communities may allow the identification of new biofilm control strategies. The purpose of the present study was to investigate the effects of metabolite molecules produced by bacteria isolated from DW on biofilm formation. Six opportunistic bacteria, viz. Acinetobacter calcoaceticus, Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata and Staphylococcus sp. isolated from a drinking water distribution systems (DWDS) were used to form single and multispecies biofilms in the presence and absence of crude cell-free supernatants produced by the partner bacteria. Biofilms were characterized in terms of mass and metabolic activity. Additionally, several physiological aspects regulating interspecies interactions (sessile growth rates, antimicrobial activity of cell-free supernatants, and production of iron chelators) were studied to identify bacterial species with biocontrol potential in DWDS. Biofilms of Methylobacterium sp. had the highest growth rate and M. mucogenicum biofilms the lowest. Only B. cepacia was able to produce extracellular iron-chelating molecules. A. calcoaceticus, B. cepacia, Methylobacterium sp. and M. mucogenicum biofilms were strongly inhibited by crude cell-free supernatants from the other bacteria. The crude cell-free supernatants of M. mucogenicum and S. capsulata demonstrated a high potential for inhibiting the growth of counterpart biofilms. Multispecies biofilm formation was strongly inhibited in the absence of A. calcoaceticus. Only crude cell-free supernatants produced by B. cepacia and A. calcoaceticus had no inhibitory effects on multispecies biofilm formation, while metabolite molecules of M. mucogenicum showed the most significant biocontrol potential.

  17. Exploration and conservation of bacterial genetic resources as bacteriocin producing inhibitory microorganisms to pathogen bacteria in livestock

    Directory of Open Access Journals (Sweden)

    Chotiah S

    2013-06-01

    Full Text Available Exploration and conservation of microorganisms producing bacteriocin was done as the primary study towards the collection of potential bacteria and its application in improving livestock health condition and inhibit food borne pathogens. Diferent kinds of samples such as beef cattle rectal swab, rumen fluids, cow’s milk, chicken gut content, goat’s milk were collected at Bogor cattle slaughter houses, poultry slaughter houses, dairy cattle and goat farms. A total of 452 bacterial isolates consisted of 73 Gram negative bacteria and 379 Gram positive bacteria were isolated from samples collected and screened for bacteriocin activity. Determination of bacteriocin activity with bioassay using agar spot tests were carried out on liquid and semisolid medium assessing 8 kins of indicators of pathogenic bacteria and food borne pathogens. A total of 51 bacteriocin producing strains were collected and some of the strains had high inhibitory zone such as Lactobacillus casei SS14C (26 mm, Enterobacter cloacae SRUT (24mm, Enterococcus faecalis SK39 (21mm and Bifidobacterium dentium SS14T (20mm respectively, to Salmonella typhimurium BCC B0046/ATCC 13311, E. coli O157 hemolytic BCC B2717, Listeria monocytogenes BCC B2767/ATCC 7764 and Escherichia coli VTEC O157 BCC B2687. Evaluation after conservation ex situ to all bacterocin producing strain at 5oC for 1 year in freeze drying ampoules in vacuum and dry condition revealed the decreasing viability starting from log 0.8 CFU/ml for Lactococcus and Leuconostoc to log 2.2. CFU/ml for Streptococcus. Result of the study showed that the bacteriocin producing strains obtained were offered a potential resource for preventing disease of livestock and food borne diseases.

  18. Isolation and Identification of Crude Oil Degrading and Biosurfactant Producing Bacteria from the Oil-Contaminated Soils of Gachsaran

    Directory of Open Access Journals (Sweden)

    Seyyedeh Zahra Hashemi

    2016-03-01

    Full Text Available Background and Objectives: Petroleum hydrocarbons are harmful to the environment, human health, and all other living creatures. Oil and its byproducts in contact with water block sunshine to phytoplanktons and thus break the food chain and damage the marine food source. This study aims to isolate the crude oil degrading and biosurfactant producing bacteria from the oil contaminated soils of Gachsaran, Iran. Materials and Methods: Isolation was performed in peptone-water medium with yeast extract. Oil displacement area, emulsification index and bacterial phylogeny using 16S rRNA analysis were studied. Results and Conclusion: Three isolates were able to degrade the crude oil. In the first day, there were two phases in the medium; after a few days, these three bacteria degraded the crude oil until there was only one phase left in the medium. One strain was selected as a superior strain by homogenizing until the medium became clear and transparent. This method confirmed that the strain produces biosurfactant. According to the morphological and biochemical tests, the strain isolated from the oil contaminated soils is a member of Bacillus subtilis, so to study the bacterial phylogeny and taxonomy of the strain, an analysis of 16S rRNA was carried out, and the phylogenic tree confirmed them. The results verified that oil contaminated soils are good source for isolation of the biosurfactant producing bacteria.

  19. In vitro evaluation of bacteriocin-like inhibitory substances produced by lactic acid bacteria isolated during traditional Sicilian cheese making

    Directory of Open Access Journals (Sweden)

    Giusi Macaluso

    2016-02-01

    Full Text Available Bacteriocins are antimicrobial proteins produced by bacteria that inhibit the growth of other bacteria with a bactericidal or bacteriostatic mode of action. Many lactic acid bacteria (LAB produce a high diversity of different bacteriocins. Bacteriocinogenic LAB are generally recognised as safe (GRAS and useful to control the frequent development of pathogens and spoilage microorganisms. For this reason they are commonly used as starter cultures in food fermentations. In this study, the authors describe the results of a screening on 699 LAB isolated from wooden vat surfaces, raw milk and traditional Sicilian cheeses, for the production of bacteriocin-like inhibitory substances, by comparing two alternative methods. The antagonistic activity of LAB and its proteinaceous nature were evaluated using the spot-on-the-lawn and the well-diffusion assay (WDA and the sensitivity to proteolytic (proteinase K, protease B and trypsin, amylolytic (α-amylase and lipolytic (lipase enzymes. The indicator strains used were: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Salmonella enteritidis. A total of 223 strains (belonging to the species Enterococcus spp., Lactobacillus spp., Pediococcus spp., Streptococcus spp., Leuconostoc spp. and Lactococcus lactis were found to inhibit the growth of Listeria monocytogenes by using the spot-on-the-lawn method; only 37 of these were confirmed by using the WDA. The direct addition of bacteriocin-producing cultures into dairy products can be a more practical and economic option for the improvement of the safety and quality of the final product.

  20. In Vitro Evaluation of Bacteriocin-Like Inhibitory Substances Produced by Lactic Acid Bacteria Isolated During Traditional Sicilian Cheese Making

    Science.gov (United States)

    Macaluso, Giusi; Fiorenza, Gerlando; Gaglio, Raimondo; Mancuso, Isabella

    2016-01-01

    Bacteriocins are antimicrobial proteins produced by bacteria that inhibit the growth of other bacteria with a bactericidal or bacteriostatic mode of action. Many lactic acid bacteria (LAB) produce a high diversity of different bacteriocins. Bacteriocinogenic LAB are generally recognised as safe (GRAS) and useful to control the frequent development of pathogens and spoilage microorganisms. For this reason they are commonly used as starter cultures in food fermentations. In this study, the authors describe the results of a screening on 699 LAB isolated from wooden vat surfaces, raw milk and traditional Sicilian cheeses, for the production of bacteriocin-like inhibitory substances, by comparing two alternative methods. The antagonistic activity of LAB and its proteinaceous nature were evaluated using the spot-on-the-lawn and the well-diffusion assay (WDA) and the sensitivity to proteolytic (proteinase K, protease B and trypsin), amylolytic (a-amylase) and lipolytic (lipase) enzymes. The indicator strains used were: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Salmonella enteritidis. A total of 223 strains (belonging to the species Enterococcus spp., Lactobacillus spp., Pediococcus spp., Streptococcus spp., Leuconostoc spp. and Lactococcus lactis) were found to inhibit the growth of Listeria monocytogenes by using the spot-on-the-lawn method; only 37 of these were confirmed by using the WDA. The direct addition of bacteriocin-producing cultures into dairy products can be a more practical and economic option for the improvement of the safety and quality of the final product.

  1. [Antibacterial effect of food additives and detergents against histamine-producing bacteria on food contact material surfaces].

    Science.gov (United States)

    Kamii, Eri; Terada, Gaku; Akiyama, Junki; Isshiki, Kenji

    2011-01-01

    We investigated the antibacterial activity of food additives and detergents against histamine-producing bacteria on food contact material surfaces. Based on minimum inhibitory concentration (MIC) testing with Morganella morganii NBRC3848, Raoultella planticola NBRC3317 and Enterobacter aerogenes NCTC10006, we screened nine food additives and four detergents with relatively high inhibitory potency. We prepared food contact material surfaces contaminated with histamine-producing bacteria, and dipped them into fourteen agents (100 µg/mL). Sodium hypochlorite, benzalkonium chloride, benzethonium chloride, n-hexadecyltrimethylammonium chloride and 1-n-hexadecylpyridinium chloride showed antibacterial activity against histamine-producing bacteria. We prepared low concentrations of the five agents (10 and 50 µg/mL) and tested them in the same way. Sodium hypochlorite showed high antibacterial activity at 10 µg/mL, and the other four showed activity at 50 µg/mL. So, washing the material surface with these reagents might be effective to prevent histamine food poisoning owing to bacterial contamination of food contact surfaces.

  2. Modeling the competition between PHA-producing and non-PHA-producing bacteria in feast-famine SBR and staged CSTR systems.

    Science.gov (United States)

    Marang, Leonie; van Loosdrecht, Mark C M; Kleerebezem, Robbert

    2015-12-01

    Although the enrichment of specialized microbial cultures for the production of polyhydroxyalkanoates (PHA) is generally performed in sequencing batch reactors (SBRs), the required feast-famine conditions can also be established using two or more continuous stirred-tank reactors (CSTRs) in series with partial biomass recirculation. The use of CSTRs offers several advantages, but will result in distributed residence times and a less strict separation between feast and famine conditions. The aim of this study was to investigate the impact of the reactor configuration, and various process and biomass-specific parameters, on the enrichment of PHA-producing bacteria. A set of mathematical models was developed to predict the growth of Plasticicumulans acidivorans-as a model PHA producer-in competition with a non-storing heterotroph. A macroscopic model considering lumped biomass and an agent-based model considering individual cells were created to study the effect of residence time distribution and the resulting distributed bacterial states. The simulations showed that in the 2-stage CSTR system the selective pressure for PHA-producing bacteria is significantly lower than in the SBR, and strongly affected by the chosen feast-famine ratio. This is the result of substrate competition based on both the maximum specific substrate uptake rate and substrate affinity. Although the macroscopic model overestimates the selective pressure in the 2-stage CSTR system, it provides a quick and fairly good impression of the reactor performance and the impact of process and biomass-specific parameters.

  3. H2O2-Fe2+法处理3-羟基-2-萘甲酸生产废水%Experimental Study on Treating Wastewater from Producing 2-Naphthalene Carboxylic Acid,3-hydroxy by Chemical Catalytic Oxidation Method

    Institute of Scientific and Technical Information of China (English)

    李亚丽; 张小平; 蔡凌; 亓学梅; 黄亭; 冯辉

    2001-01-01

    采用H2O2-Fe2+法处理3-羟基-2-萘甲酸(简称2,3酸)生产废水。在pH为2.8-2.9(原液),〔FeSO4·7H20〕为0.5 kg/t废水,〔H2O2〕为5L/t废水,t为20 min,T为60℃-80℃时,COD去除率可达94%左右。%H2O2- Fe2+ is used to treat wastewater from producing 2-naphthalene carboxylic acid, 3-hydroxy. The de tailed procedure involves such steps as H2O2- Fe2+ treatment, neutralization, coagulation and settlement by using H2O2 and Fe2+ as the radical reaction initiating agents.

  4. Genomewide expression analysis in amino acid-producing bacteria using DNA microarrays.

    Science.gov (United States)

    Polen, Tino; Wendisch, Volker F

    2004-01-01

    DNA microarray technology has become an important research tool for biotechnology and microbiology. It is now possible to characterize genetic diversity and gene expression in a genomewide manner. DNA microarrays have been applied extensively to study the biology of many bacteria including Escherichia coli, but only recently have they been developed for the Gram-positive Corynebacterium glutamicum. Both bacteria are widely used for biotechnological amino acid production. In this article, in addition to the design and generation of microarrays as well as their use in hybridization experiments and subsequent data analysis, we describe recent applications of DNA microarray technology regarding amino acid production in C. glutamicum and E. coli. We also discuss the impact of functional genomics studies on fundamental as well as applied aspects of amino acid production with C. glutamicum and E. coli.

  5. In vitro growth of four individual human gut bacteria on oligosaccharides produced by chemoenzymatic synthesis.

    Science.gov (United States)

    Vigsnaes, Louise K; Nakai, Hiroyuki; Hemmingsen, Lene; Andersen, Joakim M; Lahtinen, Sampo J; Rasmussen, Louise E; Hachem, Maher Abou; Petersen, Bent O; Duus, Jens Ø; Meyer, Anne S; Licht, Tine R; Svensson, Birte

    2013-04-30

    The present study aimed at examining oligosaccharides (OS) for potential stimulation of probiotic bacteria. Nineteen structurally well-defined candidate OS covering groups of β-glucosides, α-glucosides and α-galactosides with degree of polymerization 2-4 were prepared in >100 mg amounts by chemoenzymatic synthesis (i.e. reverse phosphorolysis or transglycosylation). Fourteen of the OS are not naturally occurring and five (β-D-glucosyl-fructose, β-D-glucosyl-xylitol, α-glucosyl-(1,4)-D-mannose, α-glucosyl-(1,4)-D-xylose; α-glucosyl-(1,4)-L-fucose) have recently been synthesized for the first time. These OS have not been previously tested for effects of bacterial growth and here the ability of all 19 OS to support growth of four gastrointestinal bacteria: three probiotic bacteria Bifidobacterium lactis, Bifidobacterium longum, and Lactobacillus acidophilus, and one commensal bacterium, Bacteroides vulgatus has been evaluated in monocultures. The disaccharides β-D-glucosyl-xylitol and β-D-glucosyl-(1,4)-xylose noticeably stimulated growth yields of L. acidophilus NCFM, and additionally, β-D-glucosyl-(1,4)-xylose stimulated B. longum Bl-05. α-Glucosyl-(1,4)-glucosamine and α-glucosyl-(1,4)-N-acetyl-glucosamine enhanced the growth rate of B. animalis subsp. lactis and B. longum Bl-05, whereas L. acidophilus NCFM and Bac. vulgatus did not grow on these OS. α-Galactosyl-(1,6)-α-galactosyl-(1,6)-glucose advanced the growth rate of B. animalis subsp. lactis and L. acidophilus NCFM. Thus several of the structurally well-defined OS supported growth of beneficial gut bacteria. This reflects a broad specificity of their sugar transporters for OS, including specificity for non-naturally occurring OS, hence showing promise for design of novel prebiotics.

  6. qPCR for quantitative detection of tyramine-producing bacteria in dairy products

    OpenAIRE

    Ladero Losada, Víctor Manuel; Martínez Álvarez, Noelia; Martín, M. Cruz; Fernández García, María; Álvarez González, Miguel Ángel

    2010-01-01

    Biogenic amines (BAs) are organic nitrogenous compounds that occur naturally in small concentrations in most living organisms, in which they have different biological functions. However, they can accumulate in foods due to the decarboxylating activity of certain bacteria. The consumption of food containing large amounts of some BAs can have toxicological consequences. Tyramine is one of the most active and common BAs found in cheeses. This article reports the design of an real-time quantitati...

  7. Growth Inhibition of Sulfate-Reducing Bacteria in Produced Water from the Petroleum Industry Using Essential Oils.

    Science.gov (United States)

    Souza, Pamella Macedo de; Goulart, Fátima Regina de Vasconcelos; Marques, Joana Montezano; Bizzo, Humberto Ribeiro; Blank, Arie Fitzgerald; Groposo, Claudia; Sousa, Maíra Paula de; Vólaro, Vanessa; Alviano, Celuta Sales; Moreno, Daniela Sales Alviano; Seldin, Lucy

    2017-04-19

    Strategies for the control of sulfate-reducing bacteria (SRB) in the oil industry involve the use of high concentrations of biocides, but these may induce bacterial resistance and/or be harmful to public health and the environment. Essential oils (EO) produced by plants inhibit the growth of different microorganisms and are a possible alternative for controlling SRB. We aimed to characterize the bacterial community of produced water obtained from a Brazilian petroleum facility using molecular methods, as well as to evaluate the antimicrobial activity of EO from different plants and their major components against Desulfovibrio alaskensis NCIMB 13491 and against SRB growth directly in the produced water. Denaturing gradient gel electrophoresis revealed the presence of the genera Pelobacter and Marinobacterium, Geotoga petraea, and the SRB Desulfoplanes formicivorans in our produced water samples. Sequencing of dsrA insert-containing clones confirmed the presence of sequences related to D. formicivorans. EO obtained from Citrus aurantifolia, Lippia alba LA44 and Cymbopogon citratus, as well as citral, linalool, eugenol and geraniol, greatly inhibited (minimum inhibitory concentration (MIC) = 78 µg/mL) the growth of D. alaskensis in a liquid medium. The same MIC was obtained directly in the produced water with EO from L. alba LA44 (containing 82% citral) and with pure citral. These findings may help to control detrimental bacteria in the oil industry.

  8. Growth Inhibition of Sulfate-Reducing Bacteria in Produced Water from the Petroleum Industry Using Essential Oils

    Directory of Open Access Journals (Sweden)

    Pamella Macedo de Souza

    2017-04-01

    Full Text Available Strategies for the control of sulfate-reducing bacteria (SRB in the oil industry involve the use of high concentrations of biocides, but these may induce bacterial resistance and/or be harmful to public health and the environment. Essential oils (EO produced by plants inhibit the growth of different microorganisms and are a possible alternative for controlling SRB. We aimed to characterize the bacterial community of produced water obtained from a Brazilian petroleum facility using molecular methods, as well as to evaluate the antimicrobial activity of EO from different plants and their major components against Desulfovibrio alaskensis NCIMB 13491 and against SRB growth directly in the produced water. Denaturing gradient gel electrophoresis revealed the presence of the genera Pelobacter and Marinobacterium, Geotoga petraea, and the SRB Desulfoplanes formicivorans in our produced water samples. Sequencing of dsrA insert-containing clones confirmed the presence of sequences related to D. formicivorans. EO obtained from Citrus aurantifolia, Lippia alba LA44 and Cymbopogon citratus, as well as citral, linalool, eugenol and geraniol, greatly inhibited (minimum inhibitory concentration (MIC = 78 µg/mL the growth of D. alaskensis in a liquid medium. The same MIC was obtained directly in the produced water with EO from L. alba LA44 (containing 82% citral and with pure citral. These findings may help to control detrimental bacteria in the oil industry.

  9. Effect of Indole-3-Acetic Acid-Producing Bacteria on Phytoremediation of Soil Contaminated with Phenanthrene and Anthracene by Mungbean

    Directory of Open Access Journals (Sweden)

    Waraporn Chouychai

    2016-07-01

    Full Text Available The use of indole-3-acetic acid (IAA-producing bacteria isolated from non-contaminated weed rhizosphere to enhance plant growth and PAH phytoremediation capacity was investigated. IAA-producing bacterial isolates, designated NSRU1, NSRU2, and NSRU3, were isolated from the rhizosphere of Eleusine indica (Poaceae and Chromolaena odorata (Asteraceae. The isolates were able to produce IAA in nutrient broth. However, when grown in the presence of 100 mg/l of either phenanthrene or anthracene, the amount of IAA produced by each isolate was reduced significantly. Mungbean seedlings were planted in 100 mg/kg phenanthrene- or anthracene-contaminated soil without or with inoculation of ≈106 CFU/g dry soil with one of the bacterial isolates. Inoculation with either NSRU1 or NSRU2 was effective at enhancing shoot length of mungbean in phenanthrene-contaminated soil on day 16. Also, inoculation with isolate NSRU1 led to increased root dry weight of mungbean in phenanthrene-contaminated soil on day 30. Phenanthrene and anthracene degradation on day 16 and 30 in planted and inoculated soil ranged between 92 - 93.8% and 92.2 - 94.1%, respectively, which were not significantly different from planted and uninoculated soil (93.9 and 94.9%. These data showed that IAA-producing bacteria could enhance plant growth, but was unable to increase PAH biodegradation under the conditions tested.

  10. Cold-active hydrolases producing bacteria from two different sub-glacial Himalayan lakes.

    Science.gov (United States)

    Sahay, Harmesh; Babu, Bandamaravuri Kishore; Singh, Surendra; Kaushik, Rajeev; Saxena, Anil K; Arora, Dilip K

    2013-08-01

    Microorganisms, native to the cold environments have successfully acclimatized their physiological, metabolic, and biological features, exhibiting uniqueness in their enzymes, proteins, and membrane structures. These cold-active enzymes have immense biotechnological potential. The diversity of culturable bacteria in two different water lakes (the sub-glacial freshwater and the brackish) of Himalayas was analyzed using SYBR green staining and cultural methods. A total of 140 bacteria were isolated and were grouped as psychrophiles, psychrotrophs, and psychrotolerant organisms, based on their optimal temperature for growth. The amplified ribosomal DNA restriction analysis using three restriction enzymes facilitated the grouping of these isolates into 96 genotypes at ≥85% polymorphism. Phylogenetic analysis using 16S rRNA gene sequences revealed that the bacterial strains from both lakes belonged to Firmicutes, Proteobacteria (α, β, and γ) or Actinobacteria. Screening of the germplasm for the activity of different cold-active hydrolases such as protease, amylase, xylanase, and cellulase, revealed that about 16 isolates were positive, and exhibiting a wide range of stability at various temperature and pH. Our results suggest that the distinctly different ecosystems of sub-glacial freshwater and brackish water lakes have diverse groups of bacteria, which can be an excellent source of extracellular hydrolases with a wide range of thermal stability.

  11. The partial characterization of the antibacterial peptide bacteriocin G2 produced by the probiotic bacteria Lactobacillus plantarum G2

    Directory of Open Access Journals (Sweden)

    SVETLANA L. ŠEATOVIĆ

    2011-05-01

    Full Text Available The aim of this study was the partial characterization of the antimicrobial peptide bacteriocin G2 produced by probiotic bacteria Lactobacillus plantarum G2, which was isolated from a clinical sample of a healthy person. Antimicrobial substance was secreted in the supernatant of an L. plantarum G2 culture, and showed a diverse spectrum of antimicrobial activity of all the tested strains of the genera Lactobacillus and the pathogenic bacteria Staphylococcus aureus and Salmonella аbony. Isoelectric focusing revealed that bacteriocin G2 is a cationic peptide (pI about 10 with a molecular mass of 2.2 kDa according to tricine–sodium dodecyl sulphate–polyacrylamide gel electrophoresis, SDS-PAGE. The antimicrobial activity of bacteriocin G2 was diminished by the proteolytic action of trypsin and proteinase K. Bacteriocin G2 preserved its biological activity in the temperature range 40–60 °C (15 min, which was lost at 80 °C. Bacteriocin G2 was stable in the pH range 2–9, while treatment with 1 % Tween 80 and 1 % urea resulted in increased antimicrobial activity. The probiotic strain L. plantarum G2 produces the antimicrobial substance proteinaceous in nature with bacteriocin characteristics. Bacteriocin production is one of the key properties of probiotic bacteria with clinical potential as anti-infective agents, which will increase the likelihood of its in vivo efficacy.

  12. A methodological approach to screen diverse cheese-related bacteria for their ability to produce aroma compounds.

    Science.gov (United States)

    Pogačić, Tomislav; Maillard, Marie-Bernadette; Leclerc, Aurélie; Hervé, Christophe; Chuat, Victoria; Yee, Alyson L; Valence, Florence; Thierry, Anne

    2015-04-01

    Microorganisms play an important role in the development of cheese flavor. The aim of this study was to develop an approach to facilitate screening of various cheese-related bacteria for their ability to produce aroma compounds. We combined i) curd-based slurry medium incubated under conditions mimicking cheese manufacturing and ripening, ii) powerful method of extraction of volatiles, headspace trap, coupled to gas chromatography-mass spectrometry (HS-trap-GC-MS), and iii) metabolomics-based method of data processing using the XCMS package of R software and multivariate analysis. This approach was applied to eleven species: five lactic acid bacteria (Leuconostoc lactis, Lactobacillus sakei, Lactobacillus paracasei, Lactobacillus fermentum, and Lactobacillus helveticus), four actinobacteria (Brachybacterium articum, Brachybacterium tyrofermentans, Brevibacterium aurantiacum, and Microbacterium gubbeenense), Propionibacterium freudenreichii, and Hafnia alvei. All the strains grew, with maximal populations ranging from 7.4 to 9.2 log (CFU/mL). In total, 52 volatile aroma compounds were identified, of which 49 varied significantly in abundance between bacteria. Principal component analysis of volatile profiles differentiated species by their ability to produce ethyl esters (associated with Brachybacteria), sulfur compounds and branched-chain alcohols (H. alvei), branched-chain acids (H. alvei, P. freudenreichii and L. paracasei), diacetyl and related carbonyl compounds (M. gubbeenense and L. paracasei), among others.

  13. PCR of crtNM combined with analytical biochemistry: An efficient way to identify carotenoid producing lactic acid bacteria.

    Science.gov (United States)

    Turpin, Williams; Renaud, Cécile; Avallone, Sylvie; Hammoumi, Aayah; Guyot, Jean-Pierre; Humblot, Christèle

    2016-03-01

    Lactic acid bacteria (LAB) synthesize a wide variety of biochemical compounds during food fermentation. Carotenoids provide important biological functions for bacteria, and their consumption by humans has many beneficial effects. In this study, the presence of several genes involved in the production of carotenoids was determined by BLAST analysis and PCR in a collection of 156 LAB isolated from traditional amylaceous African fermented foods. Only the crtE gene and the crtNM operon were present and detected in Lactobacillaceae. Most of the strains with positive PCR detection of the operon crtNM produced carotenoid-like compounds when grown in MRS broth. The carotenoids produced differed from compounds previously identified in other LAB except for one peak, which was closely related to 4,4'-diaponeurosporene already reported in the literature in Lactobacillus plantarum species. Most producing strains belonged to Lactobacillus fermentum and L. plantarum species but a few Pediococcus acidilactici were also producers. Furthermore, the most efficient L. plantarum was able to synthesize carotenoids in a cereal fermented food. Genetic screening was shown to be efficient since, in all cases, it eliminated the need for biochemical analysis of strains in which no amplicons of the operon crtNM were obtained.

  14. Bacteriocin-Producing Lactic Acid Bacteria Isolated from Traditional Fermented Food

    Science.gov (United States)

    Kormin, Salasiah; Rusul, Gulam; Radu, Son; Ling, Foo Hooi

    2001-01-01

    Lactic Acid Bacteria (LAB) isolated from several traditional fermented foods such as “tempeh”, “tempoyak” and “tapai” were screened for the production of bacteriocin. One strain isolated from “tempeh” gives an inhibitory activity against several LAB. The strain was later identified as Lactobacillus plantarum BS2. Study shows that the inhibitory activity was not caused by hydrogen peroxide, organic acids or bacteriophage. The bacteriocin production was maximum after 10 hours of incubation with an activity of 200 AU/ml. The bacteriocin was found to be sensitive towards trypsin, α-chymotrypsin, β-chymotrypsin, α-amylase and lysozyme. PMID:22973159

  15. Isolation of bacteria producing chitinase and inhibiting growth of Rhizoctonia solani

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Five bacteria strains with higher chitinase activity were isolated by using a technique of enriched cell wall of R. solani. All of them showed inhibiting effect on the growth of R. solani. Being cultured 3 d, strain CH-1 showed higher chitinase activity on the chitin plate. The diameter of the transparent circle reached 8.7 mm (4 replications) . In the antagonistic test to R. solani in PDA plate, the circle was 18.1 mm. It was also observed that the antagonistic ability of some strains was not consistent with the chitinase activity (Table 1). It may be connected with the secretion of chitinase at different culture situations.

  16. Antimicrobial activity of Gynostemma pentaphyllum extracts against fungi producing aflatoxin and fumonisin and bacteria causing diarrheal disease.

    Science.gov (United States)

    Srichana, Darunee; Taengtip, Rattana; Kondo, Sumalee

    2011-05-01

    Gynostemma pentaphyllum was investigated to determine its antimicrobial activities against human.and animal pathogens that produce aflatoxin, fumonisin, and diarrheal disease. The fungi were Aspergillusflavus, Aspergillus parasiticus and Fusarium verticillioides. The bacteria were Vibrio, Salmonella, Shigella, Escherichia coli and Staphylococcus aureus. G. pentaphyllum was extracted by five different methods. The obtained extracts were designated Extracts A, B, C, D and E. The results of the antifungal assay against A.flavus andA. parasiticus showed Extracts A and B at 10,000 ppm inhibited growth at 8-28%. Extracts A and B at 10,000 ppm also showed activity against F. verticillioides at 41-43%. Extract A, B and C were able to inhibit the tested strains better than the Extracts D and E. The MIC values of the extracts against gram-negative bacteria ranged from pentaphyllum extracts had activity against bacterial and fungal infections and could be used to control these organisms.

  17. Isolation and Characterization of Thermophilic Cellulase-Producing Bacteria from Empty Fruit Bunches-Palm Oil Mill Effluent Compost

    Directory of Open Access Journals (Sweden)

    Azhari S. Baharuddin

    2010-01-01

    Full Text Available Problems statement: Lack of information on locally isolated cellulase-producing bacterium in thermophilic compost using a mixture of Empty Fruit Bunch (EFB and Palm Oil Mill Effluent (POME as composting materials. Approach: The isolation of microbes from compost heap was conducted at day 7 of composting process where the mixture of composting materials consisted of 45.8% cellulose, 17.1% hemicellulose and 28.3% lignin content. The temperature, pH and moisture content of the composting pile at day 7 treatment were 58.3, 8.1 and 65.5°C, respectively. The morphological analysis of the isolated microbes was conducted using Scanning Electron Microscope (SEM and Gram stain method. The congo red test was conducted in order to detect 1% CMC agar degradation activities. Total genomic DNAs were extracted from approximately 1.0 g of mixed compost and amplified by using PCR primers. The PCR product was sequent to identify the nearest relatives of 16S rRNA genes. The localization of bacteria chromosomes was determined by Fluorescence In Situ Hybridization (FISH analysis. Results: Single isolated bacteria species was successfully isolated from Empty Fruit Bunch (EFB-Palm Oil Mill Effluent (POME compost at thermophilic stage. Restriction fragment length polymorphism profiles of the DNAs coding for the 16S rRNAs with the phylogenetic analysis showed that the isolated bacteria from EFB-POME thermophilic compost gave the highest homology (99% with similarity to Geobacillus pallidus. The strain was spore forming bacteria and able to grow at 60°C with pH 7. Conclusion: Thermophilic bacteria strain, Geobacillus pallidus was successfully isolated from Empty Fruit Bunch (EFB and Palm Oil Mil Effluent (POME compost and characterized.

  18. H2@Scale Resource and Market Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ruth, Mark

    2017-05-04

    The 'H2@Scale' concept is based on the potential for wide-scale utilization of hydrogen as an energy intermediate where the hydrogen is produced from low cost energy resources and it is used in both the transportation and industrial sectors. H2@Scale has the potential to address grid resiliency, energy security, and cross-sectoral emissions reductions. This presentation summarizes the status of an ongoing analysis effort to quantify the benefits of H2@Scale. It includes initial results regarding market potential, resource potential, and impacts of when electrolytic hydrogen is produced with renewable electricity to meet the potential market demands. It also proposes additional analysis efforts to better quantify each of the factors.

  19. Antimicrobial resistance of coagulase-negative staphylococci and lactic acid bacteria from industrially produced dairy products

    Directory of Open Access Journals (Sweden)

    Nevijo Zdolec

    2013-03-01

    Full Text Available In this research, the susceptibility to clindamycin, tetracycline, amikacin, amoxicillin + clavulanic acid, enrofloxacine, vancomycin, trimethoprim + sulphametoxazol, tobramycin, chloramphenicol, ciprofloxacin, erythromycin, penicillin and trimethoprim was tested in coagulase-negative staphylococci (n=78 and lactic acid bacteria (n=30 by means of disk diffusion test and E-test. The isolates were collected from soft and hard cheeses, butter and brine. All isolates of coagulase-negative staphylococci were susceptible to clindamycin, amikacin, amoxicillin + clavulanic acid, enrofloxacine, vancomycin, chloramphenicol and ciprofloxacin according to CLSI breakpoints. A total of 30 staphylococci isolates (38.46 % were resistant to erythromycin, 18 to penicillin (23.07 %, 4 to tetracycline (5.12 %, and one isolate to trimethoprim, tobramicin and trimethoprim + sulphametoxazol (1.28 %. Among 78 tested staphylococci, 35 of them were resistant to at least one antimicrobial substance (44.87 %. The rate of resistant isolates of different soft cheese types ranged from 22 to 70 %, while resistant staphylococci were absent in hard cheese and brine. The growth of lactic acid bacteria was not influenced by trimethoprim + sulphametoxazol (n=29, vancomycin (n=29, trimethoprim (n=28, amikacin (n=10 and tobramycin (n=10. The results show that significant part of apathogenic microbiota in different dairy products is phenotypically resistant to antimicrobial agents.

  20. Performance study of biofilter developed to treat H2S from wastewater odour.

    Science.gov (United States)

    Omri, Ilhem; Aouidi, Fethia; Bouallagui, Hassib; Godon, Jean-Jacques; Hamdi, Moktar

    2013-04-01

    Biofiltration is an efficient biotechnological process used for waste gas abatement in various industrial processes. It offers low operating and capital costs and produces minimal secondary waste streams. The objective of this study was to evaluate the performance of a pilot scale biofilter in terms of pollutants' removal efficiencies and the bacterial dynamics under different inlet concentrations of H2S. The treatment of odourous pollutants by biofiltration was investigated at a municipal wastewater treatment plant (WWTP) (Charguia, Tunis, Tunisia). Sampling and analyses were conducted for 150 days. Inlet H2S concentration recorded was between 200 and 1300 mg H2S.m(-3). Removal efficiencies reached 99% for the majority of the running time at an empty bed retention time (EBRT) of 60 s. Heterotrophic bacteria were found to be the dominant microorganisms in the biofilter. The bacteria were identified as the members of the genus Bacillus, Pseudomonas and xanthomonadacea bacterium. The polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) method showed that bacterial community profiles changed with the H2S inlet concentration. Our results indicated that the biofilter system, containing peat as the packing material, was proved able to remove H2S from the WWTP odourous pollutants.

  1. First cases of KPC-type carbapenemase-producing bacteria in patients in New Zealand hospitals.

    Science.gov (United States)

    Heffernan, Helen; Dyet, Kristin; Munroe, Sean; Creighton, Julie; Chan, Sam; Taylor, Susan; Mansell, Chris

    2014-12-01

    The emergence and global spread of Klebsiella pneumoniae carbapenemases (KPCs) is a significant public health problem. Between October 2010 and July 2013, KPC-producing K. pneumoniae were isolated from four patients in New Zealand hospitals. These cases are the first known isolations of KPC-producing organisms in New Zealand. All four patients were transferred from, or had recently been in, hospitals in countries where KPC-producing organisms are prevalent (China, India, Greece and Italy). The blaKPC-2 gene was identified in the isolates from three patients and blaKPC-3 was identified in the isolate from the remaining patient. The isolates belonged to different multilocus sequence type clonal complexes, usually those prevalent in the country in which the patient had been previously hospitalised. Currently in New Zealand, the common factor associated with having a KPC-producing organism is prior hospitalisation in another country where these organisms are prevalent.

  2. Sensory acceptance and survival of probiotic bacteria in ice cream produced with different overrun levels.

    Science.gov (United States)

    Ferraz, Juliana L; Cruz, Adriano G; Cadena, Rafael S; Freitas, Monica Q; Pinto, Uelinton M; Carvalho, Celio C; Faria, Jose A F; Bolini, Helena M A

    2012-01-01

    The effect of different overrun levels on the sensory acceptance and survival of probiotic bacteria in ice cream was investigated. Vanilla ice creams supplemented with Lactobacillus acidophilus were processed with overruns of 45%, 60%, and 90%. Viable probiotic bacterial counts and sensory acceptance were assessed. All the ice creams presented a minimum count of 6 log CFU/g at the end of 60 d of frozen storage. However, higher overrun levels negatively influenced cell viability, being reported a decrease of 2 log CFU/g for the 90% overrun treatment. In addition, it was not reported an influence about acceptability with respect to appearance, aroma, and taste of the ice creams (P > 0.05). Overall, the results suggest that lower overrun levels should be adopted during the manufacture of ice cream in order to maintain its probiotic status through the shelf life.

  3. Medical and Personal Care Applications of Bacteriocins Produced by Lactic Acid Bacteria

    Science.gov (United States)

    Dicks, L. M. T.; Heunis, T. D. J.; van Staden, D. A.; Brand, A.; Noll, K. Sutyak; Chikindas, M. L.

    The frequent use of antibiotics has led to a crisis in the antibiotic ­resistance of pathogens associated with humans and animals. Antibiotic resistance and the emergence of multiresistant bacterial pathogens have led to the investigation of alternative antimicrobial agents to treat and prevent infections in both humans and animals. Research on antimicrobial peptides, with a special interest on bacteriocins of lactic acid bacteria, is entering a new era with novel applications other than food preservation. Many scientists are now focusing on the application of these peptides in medicinal and personal care products. However, it is difficult to assess the success of such ventures due to the dearth of information that has been published and the lack of clinical trials.

  4. Isolation and screening of polyhydroxyalkanoates producing bacteria from pulp, paper, and cardboard industry wastes.

    Science.gov (United States)

    Bhuwal, Anish Kumari; Singh, Gulab; Aggarwal, Neeraj Kumar; Goyal, Varsha; Yadav, Anita

    2013-01-01

    Background. Polyhydroxyalkanoates (PHAs) are storage materials that accumulate by various bacteria as energy and carbon reserve materials. They are biodegradable, environmentally friendly, and also biocompatible bioplastics. Unlike petrochemical-based plastics that take several decades to fully degrade, PHAs can be completely degraded within a year by variety of microorganisms into CO2 and water. In the present study, we aim to utilize pulp, paper, and cardboard industry sludge and waste water for the isolation and screening of polyhydroxyalkanoates (PHAs) accumulating bacteria and production of cost-effective PHB using cardboard industry waste water. Results. A total of 42 isolates showed black-blue coloration when stained with Sudan black B, a preliminary screening agent for lipophilic compounds, and a total of 15 isolates showed positive result with Nile blue A staining, a more specific dye for PHA granules. The isolates NAP11 and NAC1 showed maximum PHA production 79.27% and 77.63% with polymer concentration of 5.236 g/L and 4.042 g/L with cardboard industry waste water. Both of the selected isolates, NAP11 and NAC1, were classified up to genus level by studying their morphological and biochemical characteristics and were found to be Enterococcus sp., Brevundimonas sp. and, respectively. Conclusion. The isolates Enterococcus sp. NAP11 and Brevundimonas sp. NAC1 can be considered as good candidates for industrial production of PHB from cardboard industry waste water. We are reporting for the first time the use of cardboard industry waste water as a cultivation medium for the PHB production.

  5. Isolation and Screening of Polyhydroxyalkanoates Producing Bacteria from Pulp, Paper, and Cardboard Industry Wastes

    Directory of Open Access Journals (Sweden)

    Anish Kumari Bhuwal

    2013-01-01

    Full Text Available Background. Polyhydroxyalkanoates (PHAs are storage materials that accumulate by various bacteria as energy and carbon reserve materials. They are biodegradable, environmentally friendly, and also biocompatible bioplastics. Unlike petrochemical-based plastics that take several decades to fully degrade, PHAs can be completely degraded within a year by variety of microorganisms into CO2 and water. In the present study, we aim to utilize pulp, paper, and cardboard industry sludge and waste water for the isolation and screening of polyhydroxyalkanoates (PHAs accumulating bacteria and production of cost-effective PHB using cardboard industry waste water. Results. A total of 42 isolates showed black-blue coloration when stained with Sudan black B, a preliminary screening agent for lipophilic compounds, and a total of 15 isolates showed positive result with Nile blue A staining, a more specific dye for PHA granules. The isolates NAP11 and NAC1 showed maximum PHA production 79.27% and 77.63% with polymer concentration of 5.236 g/L and 4.042 g/L with cardboard industry waste water. Both of the selected isolates, NAP11 and NAC1, were classified up to genus level by studying their morphological and biochemical characteristics and were found to be Enterococcus sp., Brevundimonas sp. and, respectively. Conclusion. The isolates Enterococcus sp. NAP11 and Brevundimonas sp. NAC1 can be considered as good candidates for industrial production of PHB from cardboard industry waste water. We are reporting for the first time the use of cardboard industry waste water as a cultivation medium for the PHB production.

  6. Isolation and Screening of Polyhydroxyalkanoates Producing Bacteria from Pulp, Paper, and Cardboard Industry Wastes

    Science.gov (United States)

    Bhuwal, Anish Kumari; Singh, Gulab; Aggarwal, Neeraj Kumar; Goyal, Varsha; Yadav, Anita

    2013-01-01

    Background. Polyhydroxyalkanoates (PHAs) are storage materials that accumulate by various bacteria as energy and carbon reserve materials. They are biodegradable, environmentally friendly, and also biocompatible bioplastics. Unlike petrochemical-based plastics that take several decades to fully degrade, PHAs can be completely degraded within a year by variety of microorganisms into CO2 and water. In the present study, we aim to utilize pulp, paper, and cardboard industry sludge and waste water for the isolation and screening of polyhydroxyalkanoates (PHAs) accumulating bacteria and production of cost-effective PHB using cardboard industry waste water. Results. A total of 42 isolates showed black-blue coloration when stained with Sudan black B, a preliminary screening agent for lipophilic compounds, and a total of 15 isolates showed positive result with Nile blue A staining, a more specific dye for PHA granules. The isolates NAP11 and NAC1 showed maximum PHA production 79.27% and 77.63% with polymer concentration of 5.236 g/L and 4.042 g/L with cardboard industry waste water. Both of the selected isolates, NAP11 and NAC1, were classified up to genus level by studying their morphological and biochemical characteristics and were found to be Enterococcus sp., Brevundimonas sp. and, respectively. Conclusion. The isolates Enterococcus sp. NAP11 and Brevundimonas sp. NAC1 can be considered as good candidates for industrial production of PHB from cardboard industry waste water. We are reporting for the first time the use of cardboard industry waste water as a cultivation medium for the PHB production. PMID:24288534

  7. Multiplex PCR method for the simultaneous detection of histamine-, tyramine-, and putrescine-producing lactic acid bacteria in foods.

    Science.gov (United States)

    Marcobal, Angela; de las Rivas, Blanca; Moreno-Arribas, M Victoria; Muñoz, Rosario

    2005-04-01

    In a screening of primers, we have selected three pairs of primers for a multiplex PCR assay for the simultaneous detection of lactic acid bacteria (LAB) strains, which potentially produce histamine, tyramine, and putrescine on fermented foods. These primers were based on sequences from histidine, tyrosine, and ornithine decarboxylases from LAB. Under the optimized conditions, the assay yielded a 367-bp DNA fragment from histidine decarboxylases, a 924-bp fragment from tyrosine decarboxylases, and a 1,446-bp fragment from ornithine decarboxylases. When the DNAs of several target organisms were included in the same reaction, two or three corresponding amplicons of different sizes were observed. This assay was useful for the detection of amine-producing bacteria in control collection strains and in a LAB collection. No amplification was observed with DNA from nonproducing LAB strains. This article is the first describing a multiplex PCR approach for the simultaneous detection of potentially amine-producing LAB in foods. It can be easily incorporated into the routine screening for the accurate selection of starter LAB and in food control laboratories.

  8. Effect of quorum sensing signals produced by seaweed-associated bacteria on carpospore liberation from Gracilaria dura

    Directory of Open Access Journals (Sweden)

    Ravindra Pal Singh

    2015-03-01

    Full Text Available Epiphytic and endophytic bacteria associated with green macroalgae Ulva (U. fasciata and U. lactuca and red macroalgae Gracilaria (G. corticata and G. dura have been identified from three different seasons to evaluate the effect of quorum sensing molecules on carpospores liberation from Gracilaria dura. The bacterial isolates belonging to the orders Bacillales, Pseudomonadales, Alteromonadales and Vibrionales were present in all seasons, whereas Actinomycetales and Enterobacteriales were confined to pre-monsoon and post-monsoon seasons, respectively. Among all the Gram-negative bacteria, seven isolates were found to produce different types of N-acyl homoserine lactones (AHLs. Interestingly, Shewanella algae produced five types of AHL: C4-HSL, HC4-HSL, C6-HSL, 3-oxo-C6-HSL and 3-oxo-C12-HSL. Subsequently, the AHLs producing bacterial isolates were screened for carpospore liberation from G. dura and these isolates were found to positively induce carpospore liberation over the control. Also, observed that carpospore liberation increased significantly in C4- and C6-HSL treated cystocarps. Sodium dodecyl sulfate and native polyacrylamide gel electrophoresis of the total protein of the C4- and C6-HSL-treated cystocarps showed two specific peptide bands of different molecular weights (50 kDa and 60 kDa as compared to the control, confirming their indirect effect on carpospore liberation.

  9. Effect of quorum sensing signals produced by seaweed-associated bacteria on carpospore liberation from Gracilaria dura.

    Science.gov (United States)

    Singh, Ravindra Pal; Baghel, Ravi S; Reddy, C R K; Jha, Bhavanath

    2015-01-01

    Epiphytic and endophytic bacteria associated with green macroalgae Ulva (U. fasciata and U. lactuca) and red macroalgae Gracilaria (G. corticata and G. dura) have been identified from three different seasons to evaluate the effect of quorum sensing (QS) molecules on carpospores liberation from Gracilaria dura. The bacterial isolates belonging to the orders Bacillales, Pseudomonadales, Alteromonadales, and Vibrionales were present in all seasons, whereas Actinomycetales and Enterobacteriales were confined to pre-monsoon and post-monsoon seasons, respectively. Among all the Gram-negative bacteria, seven isolates were found to produce different types of N-acyl homoserine lactones (AHLs). Interestingly, Shewanella algae produced five types of AHL: C4-HSL, HC4-HSL, C6-HSL, 3-oxo-C6-HSL, and 3-oxo-C12-HSL. Subsequently, the AHLs producing bacterial isolates were screened for carpospore liberation from G. dura and these isolates were found to positively induce carpospore liberation over the control. Also, observed that carpospore liberation increased significantly in C4- and C6-HSL treated cystocarps. Sodium dodecyl sulfate and native polyacrylamide gel electrophoresis of the total protein of the C4- and C6-HSL treated cystocarps showed two specific peptide bands of different molecular weights (50 kDa and 60 kDa) as compared to the control, confirming their indirect effect on carpospore liberation.

  10. Dynamics of hydrogen-producing bacteria in a repeated batch fermentation process using lake sediment as inoculum.

    Science.gov (United States)

    Romano, Stefano; Paganin, Patrizia; Varrone, Cristiano; Tabacchioni, Silvia; Chiarini, Luigi

    2014-02-01

    In this study, we evaluated the effectiveness of lake sediment as inoculum for hydrogen production through dark fermentation in a repeated batch process. In addition, we investigated the effect of heat treatment, applied to enrich hydrogen-producing bacteria, on the bacterial composition and metabolism. Denaturing gradient gel electrophoresis and molecular cloning, both performed using the 16S rDNA gene as target gene, were used to monitor the structure of the bacterial community. Hydrogen production and bacterial metabolism were analysed via gas chromatography and high-performance liquid chromatography. Both treated and non-treated inocula were able to produce high amounts of hydrogen. However, statistical analysis showed a clear difference in their bacterial composition and metabolism. The heat treatment favoured the growth of different Clostridia sp., in particular of Clostridium bifermentans, allowing the production of a constant amount of hydrogen over prolonged time. These cultures showed both butyrate and ethanol fermentation types. Absence of heat treatment allowed species belonging to the genera Bacillus, Sporolactobacillus and Massilia to outgrow Clostridia sp. with a reduction in hydrogen production and a significant metabolic change. Our data indicate that lake sediment harbours bacteria that can efficiently produce hydrogen over prolonged fermentation time. Moreover, we could show that the heat treatment stabilizes the bacterial community composition and the hydrogen production.

  11. Mercury methylation bacteria and methyl mercury producing: A review%汞甲基化细菌研究进展

    Institute of Scientific and Technical Information of China (English)

    梁小兵

    2013-01-01

    汞甲基化细菌在厌氧条件下将无机汞(Hg)转化成最高毒性的甲基汞(MeHg),通过生物富集以及在食物链中的生物放大造成人类甲基汞暴露.本文综述了水环境中汞甲基化细菌的种类、系统发生、甲基化机理、甲基汞生成的空间位置和影响因素.水环境中汞甲基化主要发生在海洋、海湾、河流和湖泊的厌氧沉积物中.硫酸盐还原菌和铁还原菌是主要的汞甲基化细菌,它们的种类、群落结构和分布制约了甲基汞的生成,从而影响人体健康.汞甲基化的生化机理的研究表明,甲基汞可能产生于不同的代谢途径,但是对于汞甲基化机理仍没有一致的认识.沉积物中汞甲基化细菌的分布影响甲基汞生成的空间位置和甲基化率.因此,水环境中的地球化学因素影响甲基化细菌的分布、甲基化率和甲基汞的生成.%Mercury methylation bacteria change inorganic mercury to the highest toxic methylmer-cury (MeHg) under anaerobic conditions, which can result the human' s MeHg exposure by bio-accumulation and biomagnification. This article reviews the species and phylogeny of mercury methylation bacteria, methylation mechanism, spatial location of MeHg producing and the affecting factors in aquatic environments. In aquatic environments, mercury methylation occurs mainly in the anaerobic sediments of oceans, estuaries, rivers and lakes. Sulfate-reducing bacteria (SRB) and iron-reducing bacteria (IRB) are the main methylation bacteria. Their species, community structure and distribution control MeHg production and effects to human health. The studies on the biochemical mechanisms of mercury methylation show that MeHg may be produced from different metabolism pathways, but there still exist no consistent conclusions on mercury methylation mechanism. Spatial distribution of MeHg producing in sediments and the rate of mercury methylation are controlled by the distribution of mercury methylation

  12. Urinary tract infection caused by community-acquired extended-spectrum β-lactamase-producing bacteria in infants.

    Science.gov (United States)

    Kim, Yun Hee; Yang, Eun Mi; Kim, Chan Jong

    Urinary tract infection (UTI) caused by resistant strains of bacteria is increasingly prevalent in children. The aim of this study was to investigate the clinical characteristics and risk factors for UTI caused by community-acquired extended-spectrum β-lactamase (CA-ESBL)-producing bacteria in infants. This was a retrospective study performed over 5 years in a single Korean center. Hospitalized infants with febrile UTI were enrolled and divided into two groups (CA-ESBL vs. CA non-ESBL UTI). The yearly prevalence was calculated. Baseline characteristics and clinical course such as fever duration, laboratory and radiological findings were compared between the two groups. Risk factors associated with the CA-ESBL UTI were investigated. Among the enrolled infants (n=185), 31 (17%) had CA-ESBL UTI. The yearly prevalence of ESBL of CA-ESBL UTI increased during the study (0% in 2010, 22.2% in 2015). Infants with CA-ESBL UTI had a longer duration of fever after initiating antibiotics (2.0±1.1 vs. 1.5±0.6 days, p=0.020). Cortical defects on renal scan and early treatment failure were more frequent in CA-ESBL (64.5 vs. 42.2%, p=0.023; 22.6 vs. 4.5%, p=0.001). A logistic regression analysis revealed that urinary tract abnormalities and previous UTI were independent risk factors for CA-EBSL UTI (odds ratio, 2.7; p=0.025; 10.3; p=0.022). The incidence of UTI caused by ESBL-producing bacteria has increased in Korean infants. Recognition of the clinical course and risk factors for ESLB-producing UTI may help to determine appropriate guidelines for its management. Copyright © 2016. Published by Elsevier Editora Ltda.

  13. Zero prevalence of extended spectrum beta-lactamase-producing bacteria in 300 breeding Collared Flycatchers in Sweden

    Directory of Open Access Journals (Sweden)

    Josef D. Järhult

    2013-07-01

    Full Text Available Wild birds are important indicators and potential spreaders of antibiotic resistance. The order Passerines is scarcely studied apart from Corvus sp. but extended spectrum beta-lactamases (ESBLs has been found in Blackbirds. We tested 300 fecal samples from a well-studied population of Collared Flycatchers (Ficedula albicollis at the Island of Gotland in Sweden and found no ESBL-producing bacteria. These results support the idea of ‘ecological guild’ as Blackbirds are ground-foraging invertebrate feeders, whereas Collared Flycatchers are aerial insectivores not regularly coming into contact with fecal contaminations and therefore less prone to acquire pathogens spread by the fecal–oral route.

  14. Evaluating Nitrogen-Containing Biosynthetic Products Produced by Saltwater Culturing of Several California Littoral Zone Gram-Negative Bacteria.

    Science.gov (United States)

    Lorig-Roach, Nicholas; Still, Patrick C; Coppage, David; Compton, Jennifer E; Crews, Mitchell S; Navarro, Gabriel; Tenney, Karen; Crews, Phillip

    2017-08-25

    The biosynthetic potential of marine-sediment-derived Gram-negative bacteria is poorly understood. Sampling of California near-shore marine environments afforded isolation of numerous Gram-negative bacteria in the Proteobacteria and Bacteriodetes phyla, which were grown in the laboratory to provide extracts whose metabolites were identified by comparative analyses of LC-mass spectrometry and MS(n) data. Overall, we developed an assemblage of seven bacterial strains grown in five different media types designed to coax out unique secondary metabolite production as a function of varying culture conditions. The changes in metabolite production patterns were tracked using the GNPS MS(2) fragmentation pattern analysis tool. A variety of nitrogen-rich metabolites were visualized from the different strains grown in different media, and strikingly, all of the strains examined produced the same new, proton-atom-deficient compound, 1-methyl-4-methylthio-β-carboline (1), C13H12N2S. Scale-up liquid culture of Achromobacter spanius (order: Burkholderiales; class: Betaproteobacteria) provided material for the final structure elucidation. The methods successfully combined in this work should stimulate future studies of molecules from marine-derived Gram-negative bacteria.

  15. Quorum Sensing Signaling Molecules Produced by Reference and Emerging Soft-Rot Bacteria (Dickeya and Pectobacterium spp.)

    Science.gov (United States)

    Crépin, Alexandre; Barbey, Corinne; Beury-Cirou, Amélie; Hélias, Valérie; Taupin, Laure; Reverchon, Sylvie; Nasser, William; Faure, Denis; Dufour, Alain; Orange, Nicole; Feuilloley, Marc; Heurlier, Karin; Burini, Jean-François; Latour, Xavier

    2012-01-01

    Background Several small diffusible molecules are involved in bacterial quorum sensing and virulence. The production of autoinducers-1 and -2, quinolone, indole and γ-amino butyrate signaling molecules was investigated in a set of soft-rot bacteria belonging to six Dickeya or Pectobacterium species including recent or emerging potato isolates. Methodology/Principal Findings Using bacterial biosensors, immunoassay, and chromatographic analysis, we showed that soft-rot bacteria have the common ability to produce transiently during their exponential phase of growth the N-3-oxo-hexanoyl- or the N-3-oxo-octanoyl-l-homoserine lactones and a molecule of the autoinducer-2 family. Dickeya spp. produced in addition the indole-3-acetic acid in tryptophan-rich conditions. All these signaling molecules have been identified for the first time in the novel Dickeya solani species. In contrast, quinolone and γ-amino butyrate signals were not identified and the corresponding synthases are not present in the available genomes of soft-rot bacteria. To determine if the variations of signal production according to growth phase could result from expression modifications of the corresponding synthase gene, the respective mRNA levels were estimated by reverse transcriptase-PCR. While the N-acyl-homoserine lactone production is systematically correlated to the synthase expression, that of the autoinducer-2 follows the expression of an enzyme upstream in the activated methyl cycle and providing its precursor, rather than the expression of its own synthase. Conclusions/Significance Despite sharing the S-adenosylmethionine precursor, no strong link was detected between the production kinetics or metabolic pathways of autoinducers-1 and -2. In contrast, the signaling pathway of autoinducer-2 seems to be switched off by the indole-3-acetic acid pathway under tryptophan control. It therefore appears that the two genera of soft-rot bacteria have similarities but also differences in the

  16. Quorum sensing signaling molecules produced by reference and emerging soft-rot bacteria (Dickeya and Pectobacterium spp..

    Directory of Open Access Journals (Sweden)

    Alexandre Crépin

    Full Text Available BACKGROUND: Several small diffusible molecules are involved in bacterial quorum sensing and virulence. The production of autoinducers-1 and -2, quinolone, indole and γ-amino butyrate signaling molecules was investigated in a set of soft-rot bacteria belonging to six Dickeya or Pectobacterium species including recent or emerging potato isolates. METHODOLOGY/PRINCIPAL FINDINGS: Using bacterial biosensors, immunoassay, and chromatographic analysis, we showed that soft-rot bacteria have the common ability to produce transiently during their exponential phase of growth the N-3-oxo-hexanoyl- or the N-3-oxo-octanoyl-l-homoserine lactones and a molecule of the autoinducer-2 family. Dickeya spp. produced in addition the indole-3-acetic acid in tryptophan-rich conditions. All these signaling molecules have been identified for the first time in the novel Dickeya solani species. In contrast, quinolone and γ-amino butyrate signals were not identified and the corresponding synthases are not present in the available genomes of soft-rot bacteria. To determine if the variations of signal production according to growth phase could result from expression modifications of the corresponding synthase gene, the respective mRNA levels were estimated by reverse transcriptase-PCR. While the N-acyl-homoserine lactone production is systematically correlated to the synthase expression, that of the autoinducer-2 follows the expression of an enzyme upstream in the activated methyl cycle and providing its precursor, rather than the expression of its own synthase. CONCLUSIONS/SIGNIFICANCE: Despite sharing the S-adenosylmethionine precursor, no strong link was detected between the production kinetics or metabolic pathways of autoinducers-1 and -2. In contrast, the signaling pathway of autoinducer-2 seems to be switched off by the indole-3-acetic acid pathway under tryptophan control. It therefore appears that the two genera of soft-rot bacteria have similarities but also

  17. Isolation, characterization, and diversity of novel radiotolerant carotenoid-producing bacteria.

    Science.gov (United States)

    Asker, Dalal; Awad, Tarek S; Beppu, Teruhiko; Ueda, Kenji

    2012-01-01

    Carotenoids are natural pigments that exhibit many biological functions, such as antioxidants (i.e., promote oxidative stress resistance), membrane stabilizers, and precursors for vitamin A. The link between these biological activities and many health benefits (e.g., anticarcinogenic activity, prevention of chronic diseases, etc.) has raised the interest of several industrial sectors, especially in the cosmetics and pharmaceutical industries. The use of microorganisms in biotechnology to produce carotenoids is favorable by consumer and can help meet the growing demand for these bioactive compounds in the food, feed, and pharmaceutical industries. This methodological chapter details the development of a rapid and selective screening method for isolation and identification of carotenoid-producing microorganisms based on UV treatment, sequencing analysis of 16S rRNA genes, and carotenoids' analysis using rapid and effective High-Performance Liquid Chromatography-Diodearray-MS methods. The results of a comprehensive 16S rRNA gene-based phylogenetic analysis revealed a diversity of carotenoid-producing microorganisms (104 isolates) that were isolated at a high frequency from water samples collected at Misasa (Tottori, Japan), a region known for its high natural radioactivity content. These carotenoid-producing isolates were classified into 38 different species belonging to 7 bacterial classes (Flavobacteria, Sphingobacteria, α-Proteobacteria, γ-Proteobacteria, Deinococci, Actinobacteria, and Bacilli). The carotenoids produced by the isolates were zeaxanthin (6 strains), dihydroxyastaxanthin (24 strains), astaxanthin (27 strains), canthaxanthin (10 strains), and unidentified molecular species that were produced by the isolates related to Deinococcus, Exiguobacterium, and Flectobacillus. Here, we describe the methods used to isolate and classify these microorganisms.

  18. 一株产聚羟基脂肪酸酯根瘤菌Rhizobium sp.H2-5的筛选与鉴定%Screening and Identification of a Polyhydroxyalkanoate Producing Strain Rhizobium sp. H2-5

    Institute of Scientific and Technical Information of China (English)

    杨姗姗; 张红蕊; 伏圣秘; 刘新利; 陈静

    2013-01-01

    聚羟基脂肪酸酯(Polyhydroxyalkanoates,PHAs)是微生物产生的胞内能量和碳源储藏性物质,因其可以作为生物塑料具有完全可生物降解性而倍受关注.本研究从自然界中取样,经过富集培养、尼罗蓝荧光显色、苏丹黑染色、提取发酵产物红外光谱和元素分析等,筛选到一株聚羟基脂肪酸酯产生菌.通过形态观察、生理生化试验以及16S rDNA分子鉴定,确定该菌为根瘤菌Rhizobium sp.H2-5.图4参20

  19. Stochastic modelling of Listeria monocytogenes single cell growth in cottage cheese with mesophilic lactic acid bacteria from aroma producing cultures.

    Science.gov (United States)

    Østergaard, Nina Bjerre; Christiansen, Lasse Engbo; Dalgaard, Paw

    2015-07-02

    A stochastic model was developed for simultaneous growth of low numbers of Listeria monocytogenes and populations of lactic acid bacteria from the aroma producing cultures applied in cottage cheese. During more than two years, different batches of cottage cheese with aroma culture were analysed for pH, lactic acid concentration and initial concentration of lactic acid bacteria. These data and bootstrap sampling were used to represent product variability in the stochastic model. Lag time data were estimated from observed growth data (lactic acid bacteria) and from literature on L. monocytogenes single cells. These lag time data were expressed as relative lag times and included in growth models. A stochastic model was developed from an existing deterministic growth model including the effect of five environmental factors and inter-bacterial interaction [Østergaard, N.B, Eklöw, A and Dalgaard, P. 2014. Modelling the effect of lactic acid bacteria from starter- and aroma culture on growth of Listeria monocytogenes in cottage cheese. International Journal of Food Microbiology. 188, 15-25]. Growth of L. monocytogenes single cells, using lag time distributions corresponding to three different stress levels, was simulated. The simulated growth was subsequently compared to growth of low concentrations (0.4-1.0 CFU/g) of L. monocytogenes in cottage cheese, exposed to similar stresses, and in general a good agreement was observed. In addition, growth simulations were performed using population relative lag time distributions for L. monocytogenes as reported in literature. Comparably good predictions were obtained as for the simulations performed using lag time data for individual cells of L. monocytogenes. Therefore, when lag time data for individual cells are not available, it was suggested that relative lag time distributions for L. monocytogenes can be used as a qualified default assumption when simulating growth of low concentrations of L. monocytogenes.

  20. Intestinal Shiga toxin-producing Escherichia coli bacteria mitigate bovine leukemia virus infection in experimentally infected sheep.

    Science.gov (United States)

    Ferens, Witold A; Cobbold, Rowland; Hovde, Carolyn J

    2006-05-01

    Ruminants often carry gastrointestinal Shiga toxin (Stx)-producing Escherichia coli (STEC). Stxs belong to a large family of ribosome-inactivating proteins (RIPs), found in many plants and some bacteria. Plant RIPs, secreted into extracellular spaces, limit the spread of viruses through plant tissues by penetrating and killing virally infected cells. Previously, we showed Stx activity against bovine leukemia virus (BLV)-infected cells in vitro and hypothesized that STEC bacteria have antiviral activity in ruminant hosts. Here, we investigated the impact of STEC on the initial phases of BLV infection in sheep. Sheep were treated with biweekly oral doses of E. coli O157:H7 (an STEC) or an isogenic stx mutant strain. A different group of sheep were similarly treated with five naturally occurring ovine STEC isolates or stx-negative E. coli. Intestinal STEC bacteria were enumerated and identified by standard fecal culture and DNA hybridization. Oral STEC treatment did not always result in carriage of STEC, although many animals consistently presented with >10(4) CFU/g feces. BLV viremia was assessed by spontaneous lymphocyte proliferation (SLP) in cultures of blood mononuclear cells and by syncytium formation in cocultures of the same with F-81 indicator cells. SLP was lower (P < 0.05) and syncytia were fewer (P < 0.05) in STEC-treated sheep than in untreated sheep. Both lower SLP and fewer syncytia positively correlated with fecal STEC numbers. Average weight gain post-BLV challenge was higher in STEC-treated sheep than in untreated sheep (P < 0.05). These results support the hypothesis that in ruminants, intestinal STEC bacteria have antiviral activity and mitigate BLV-induced disease.

  1. The times they are a-changin': carbapenems for extended-spectrum-β-lactamase-producing bacteria.

    Science.gov (United States)

    Rodríguez-Baño, Jesús

    2015-09-01

    Several antimicrobial agents are being investigated as alternatives to carbapenems in the treatment of infections caused by ESBL-producing Enterobacteriaceae, which may be useful in avoiding overuse of carbapenems in the context of recent global spread of carbapenem-resistant Enterobacteriaceae. The most promising candidates for invasive infections so far are β-lactam/β-lactamase inhibitor combinations and cephamycins.

  2. Isolation and Selection of Anti-Candida albicans Producing Lactic Acid Bacteria

    Directory of Open Access Journals (Sweden)

    Monthon LERTCANAWANICHAKUL

    2005-06-01

    Full Text Available The forty isolates of lactic acid bacteria (LAB were obtained from various fermented foods. The cross streak plate method was used to preliminary screen for antimicrobial activity. LAB were isolated by selective medium, Mann Rogosa Sharpe (MRS. Most of the isolates showed inhibition against Staphylococcus aureus TISTR 517, Bacillus subtilis TISTR 008, Micrococcus luteus TISTR 884, Escherichia coli TISTR 887, Pseudomonas aeruginosa TISTR 781, and Candida albicans DMST 5239. Only sterile culture supernatant of isolate No. L14, later identified as Lactococcus lactis, showed antifungal activity by means of agar well diffusion assay. The activity was stable during heat treatment and was retained even after autoclaving at 121 °C for 15 minutes. Maximum activity was observed at pH values between 2.5-4.0, and was lost at higher pH values. The anti-C. albicans activity was fully regained after readjustment of the pH to the initial value (pH 3.5.

  3. Sterilization of Exopolysaccharides Produced by Deep-Sea Bacteria: Impact on Their Stability and Degradation

    Directory of Open Access Journals (Sweden)

    Sylvia Colliec-Jouault

    2011-02-01

    Full Text Available Polysaccharides are highly heat-sensitive macromolecules, so high temperature treatments are greatly destructive and cause considerable damage, such as a great decrease in both viscosity and molecular weight of the polymer. The technical feasibility of the production of exopolysaccharides by deep-sea bacteria Vibrio diabolicus and Alteromonas infernus was previously demonstrated using a bioproduct manufacturing process. The objective of this study was to determine which sterilization method, other than heat sterilization, was the most appropriate for these marine exopolysaccharides and was in accordance with bioprocess engineering requirements. Chemical sterilization using low-temperature ethylene oxide and a mixture of ionized gases (plasmas was compared to the sterilization methods using gamma and beta radiations. The changes to both the physical and chemical properties of the sterilized exopolysaccharides were analyzed. The use of ethylene oxide can be recommended for the sterilization of polysaccharides as a weak effect on both rheological and structural properties was observed. This low-temperature gas sterilizing process is very efficient, giving a good Sterility Assurance Level (SAL, and is also well suited to large-scale compound manufacturing in the pharmaceutical industry.

  4. Identification of Antarctic culturable bacteria able to produce diverse enzymes of potential biotechnological interest

    Institute of Scientific and Technical Information of China (English)

    Ignacio Ferrés; Vanesa Amarelle; Francisco Noya; Elena Fabiano

    2015-01-01

    It is estimated that more than three quarters of the Earth’s biosphere is in perennially cold environments. Despite the extreme environmental conditions of desiccation and freezing, microbes can colonize these habitats through the adaptation of metabolic functions and the synthesis of structurally adapted enzymes. Enzymes within psychrophilic microbes exhibit high specific activity at low and moderate temperature, with low thermostability. In this study we used a classic microbiological approach to isolate Antarctic bacteria with cellulolytic, lipolytic, and ligninolytic activities. From 15 different environmental samples, we generated a collection of approximately 800 bacterial isolates that could grow on R2A or Marine medium at 4°C. This collection was then screened for the presence of the three types of activity at 4°C. We found that 47.7% of the isolates displayed lipolytic activity, 10.2% had cellulase/xylanase activity, and 7.7% showed guaiacol oxidase activity. Of these, 10% displayed two different types of activity, while 0.25% displayed all three types of activity. Our results indicate that cold environments represent outstanding resources for bioprospecting and the study of enzymatic adaptation.

  5. In vitro efficacy of bioactive extracts of 15 medicinal plants against ESbetaL-producing multidrug-resistant enteric bacteria.

    Science.gov (United States)

    Ahmad, Iqbal; Aqil, Farrukh

    2007-01-01

    Alcoholic crude extracts and some fractions from 15 traditionally used Indian medicinal plants were investigated for their ability to inhibit the growth of extended spectrum beta-lactamases (ESbetaL)-producing multidrug-resistant enteric bacteria. The test bacteria Eschrichia coli and Shigella were resistant to 16-23 antibiotics with intermediate or resistance to beta-lactams (minimum inhibitory concentration (MIC) value range 16-1024 microg/ml). The crude plant extracts demonstrated zone of inhibition in the range of 11-29 mm against one or more test bacteria. On the basis of promising activity, 12 plants were selected to determine their efficacy in terms of MIC, which ranged from 0.64 mg/ml to 10.24 mg/ml. The extracts of Acorus calamus, Hemidesmus indicus, Holarrhena antidysenterica and Plumbago zeylanica demonstrated relatively high activity as compared to other plant extracts and were fractionated into acetone, ethyl acetate and methanol. Acetone fraction in most of the cases exhibited higher potency (low MIC value) as compared to ethyl acetate and methanol fraction. However, in Plumbago zeylanica, ethyl acetate fraction was most active. Synergistic interactions among crude extracts were demonstrated in the 12 different combinations against ESbetaL-producing E. coli (ESbetaL-02). Certain combinations exhibited significant synergy with enlargement of combined inhibition zone size by 5 mm. Interaction of crude extracts with five antibiotics (Tetracycline, ciprofloxacin, nalidixic acid, chloramphenicol and streptomycin) demonstrated synergistic interaction with tetracycline and ciprofloxacin by 10 and 3 plant extracts respectively. Phytochemical analysis and thin layer chromatography (TLC) bioautography of crude extracts showed the presence of alkaloids, phenols and flavonoids as active phytoconstituents. Most active fractions of four plants were subjected to Infrared spectroscopy and the major groups of compounds were detected. The plant extracts were further

  6. β-carotene-producing bacteria residing in the intestine provide vitamin A to mouse tissues in vivo.

    Science.gov (United States)

    Wassef, Lesley; Wirawan, Ruth; Chikindas, Michael; Breslin, Paul A S; Hoffman, Daniel J; Quadro, Loredana

    2014-05-01

    Vitamin A deficiency (VAD) is an overwhelming public health problem that affects hundreds of millions of people worldwide. A definitive solution to VAD has yet to be identified. Because it is an essential nutrient, vitamin A or its carotenoid precursor β-carotene can only be obtained from food or supplements. In this study, we wanted to establish whether β-carotene produced in the mouse intestine by bacteria synthesizing the provitamin A carotenoid could be delivered to various tissues within the body. To achieve this, we took advantage of the Escherichia coli MG1655*, an intestine-adapted spontaneous mutant of E. coli MG1655, and the plasmid pAC-BETA, containing the genes coding for the 4 key enzymes of the β-carotene biosynthetic pathway (geranylgeranyl pyrophosphate synthase, phytoene synthase, phytoene desaturase, and lycopene cyclase) from Erwinia herbicola. We engineered the E. coli MG1655* to produce β-carotene during transformation with pAC-BETA (MG1655*-βC) and gavaged wild-type and knockout mice for the enzyme β-carotene 15,15'-oxygenase with this recombinant strain. Various regimens of bacteria administration were tested (single vs. multiple and low vs. high doses). β-Carotene concentration was measured by HPLC in mouse serum, liver, intestine, and feces. Enumeration of MG1655*-βC cells in the feces was performed to assess efficiency of intestinal colonization. We demonstrated in vivo that probiotic bacteria could be used to deliver vitamin A to the tissues of a mammalian host. These results have the potential to pave the road for future investigations aimed at identifying alternative, novel approaches to treat VAD.

  7. Phylogeny of the ammonia-producing ruminal bacteria Peptostreptococcus anaerobius, Clostridium sticklandii, and Clostridium aminophilum sp. nov

    Science.gov (United States)

    Paster, B. J.; Russell, J. B.; Yang, C. M.; Chow, J. M.; Woese, C. R.; Tanner, R.

    1993-01-01

    In previous studies, gram-positive bacteria which grew rapidly with peptides or an amino acid as the sole energy source were isolated from bovine rumina. Three isolates, strains C, FT (T = type strain), and SR, were considered to be ecologically important since they produced up to 20-fold more ammonia than other ammonia-producing ruminal bacteria. On the basis of phenotypic criteria, the taxonomic position of these new isolates was uncertain. In this study, the 16S rRNA sequences of these isolates and related bacteria were determined to establish the phylogenetic positions of the organisms. The sequences of strains C, FT, and SR and reference strains of Peptostreptococcus anaerobius, Clostridium sticklandii, Clostridium coccoides, Clostridium aminovalericum, Acetomaculum ruminis, Clostridium leptum, Clostridium lituseburense, Clostridium acidiurici, and Clostridium barkeri were determined by using a modified Sanger dideoxy chain termination method. Strain C, a large coccus purported to belong to the genus Peptostreptococcus, was closely related to P. anaerobius, with a level of sequence similarity of 99.6%. Strain SR, a heat-resistant, short, rod-shaped organism, was closely related to C. sticklandii, with a level of sequence similarity of 99.9%. However, strain FT, a heat-resistant, pleomorphic, rod-shaped organism, was only distantly related to some clostridial species and P. anaerobius. On the basis of the sequence data, it was clear that strain FT warranted designation as a separate species. The closest known relative of strain FT was C. coccoides (level of similarity, only 90.6%). Additional strains that are phenotypically similar to strain FT were isolated in this study.(ABSTRACT TRUNCATED AT 250 WORDS).

  8. Characterization of an Antibacterial Compound, 2-Hydroxyl Indole-3-Propanamide, Produced by Lactic Acid Bacteria Isolated from Fermented Batter.

    Science.gov (United States)

    Jeevaratnam, Kadirvelu; Vidhyasagar, Venkatasubramanian; Agaliya, Perumal Jayaprabha; Saraniya, Appukuttan; Umaiyaparvathy, Muthukandan

    2015-09-01

    Lactic acid bacteria are known to produce numerous antimicrobial compounds that are active against various pathogens. Here, we have purified and characterized a novel low-molecular-weight (LMW) antimicrobial compound produced by Lactobacillus and Pediococcus isolated from fermented idly and uttapam batter. The LMW compound was extracted from cell-free supernatant using ice-cold acetone, purified by gel permeation and hydrophobic interaction chromatography. It exhibited antimicrobial activity against Gram-positive and Gram-negative pathogenic bacteria sparing the probiotic strains like Lactobacillus rhamnosus. The molecular weight of the LMW compound was identified as 204 Da using LC-MS-ESI. In addition, the structure of the compound was predicted using spectroscopic methods like FTIR and NMR and identified as 2-hydroxyl indole-3-propanamide. The LMW compound was differentiated from its related compound, tryptophan, by Salkowski reaction and thin-layer chromatography. This novel LMW compound, 2-hydroxyl indole-3-propanamide, may have an effective application as an antibiotic which can spare prevailing probiotic organisms but target only the pathogenic strains.

  9. Isolation and Taxonomic Identity of Bacteriocin-Producing Lactic Acid Bacteria from Retail Foods and Animal Sources.

    Science.gov (United States)

    Henning, Chris; Vijayakumar, Paul; Adhikari, Raj; Jagannathan, Badrinath; Gautam, Dhiraj; Muriana, Peter M

    2015-03-19

    Bacteriocin-producing (Bac⁺) lactic acid bacteria (LAB) were isolated from a variety of food products and animal sources. Samples were enriched in de Man, Rogosa, and Sharpe (MRS) Lactocilli broth and plated onto MRS agar plates using a "sandwich overlay" technique. Inhibitory activity was detected by the "deferred antagonism" indicator overlay method using Listeria monocytogenes as the primary indicator organism. Antimicrobial activity against L. monocytogenes was detected by 41 isolates obtained from 23 of 170 food samples (14%) and 11 of 110 samples from animal sources (10%) tested. Isolated Bac⁺ LAB included Lactococcus lactis, Lactobacillus curvatus, Carnobacterium maltaromaticum, Leuconostoc mesenteroides, and Pediococcus acidilactici, as well as Enterococcus faecium, Enterococcus faecalis, Enterococcus hirae, and Enterococcus thailandicus. In addition to these, two Gram-negative bacteria were isolated (Serratia plymuthica, and Serratia ficaria) that demonstrated inhibitory activity against L. monocytogenes, Staphylococcus aureus, and Enterococcus faecalis (S. ficaria additionally showed activity against Salmonella Typhimurium). These data continue to demonstrate that despite more than a decade of antimicrobial interventions on meats and produce, a wide variety of food products still contain Bac⁺ microbiota that are likely eaten by consumers and may have application as natural food preservatives.

  10. Isolation of bacteriocin - producing lactic acid bacteria from 'Ugba' and 'Okpiye', two locally fermented nigerian food condiments

    Directory of Open Access Journals (Sweden)

    Charles Ogugua Nwuche

    2013-02-01

    Full Text Available In this work, 100 samples each of 'ugba' and 'okpiye' were evaluated for the presence of bacteriocin producing lactic acid bacteria. Thirty strains showing antibacterial activity against at least one of the indicator organisms were selected from a total of 752 colonies isolated from the condiments. Out of the 30, only five strains retained activity after the pH of the broth supernatant was adjusted to 6.5. When evaluated by the agar-well diffusion assay, the spectra of inhibitory activity showed that Staphylococcus aureus was the most sensitive indicator organism tested, while Listeria monocytogenes was the most resistant. One strain (UG 2 was active against Escherichia coli. The assays using the cell-free supernatant of the cultures showed that the bacteriocins were completely inactivated by the proteolyses as well as by the chloroform treatment. In ethanol, the activity of the compounds was only partially modified. When incubated in a water bath at 80°C for 30 min, no significant activity loss was recorded. The antimicrobial activity of the bacteriocins produced by the lactic acid bacteria has potential for use in biopreservation of condiments against the spoilage and food - borne pathogens.

  11. Degradation of Polycyclic Aromatic Hydrocarbon Pyrene by Biosurfactant-Producing Bacteria Gordonia cholesterolivorans AMP 10

    OpenAIRE

    2016-01-01

    Pyrene degradation and biosurfactant activity by a new strain identified as Gordonia cholesterolivorans AMP 10 were studied. The strain grew well and produced effective biosurfactants in the presence of glucose, sucrose, and crude oil. The biosurfactants production was detected by the decreased surface tension of the medium and emulsification activity.  Analysis of microbial growth parameters showed that AMP10 grew best at 50 µg mL-1 pyrene concentration, leading to 96 % degradation of pyrene...

  12. Lithotrophic iron-oxidizing bacteria produce organic stalks to control mineral growth: implications for biosignature formation.

    Science.gov (United States)

    Chan, Clara S; Fakra, Sirine C; Emerson, David; Fleming, Emily J; Edwards, Katrina J

    2011-04-01

    Neutrophilic Fe-oxidizing bacteria (FeOB) are often identified by their distinctive morphologies, such as the extracellular twisted ribbon-like stalks formed by Gallionella ferruginea or Mariprofundus ferrooxydans. Similar filaments preserved in silica are often identified as FeOB fossils in rocks. Although it is assumed that twisted iron stalks are indicative of FeOB, the stalk's metabolic role has not been established. To this end, we studied the marine FeOB M. ferrooxydans by light, X-ray and electron microscopy. Using time-lapse light microscopy, we observed cells excreting stalks during growth (averaging 2.2  μm  h(-1)). Scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy show that stalks are Fe(III)-rich, whereas cells are low in Fe. Transmission electron microscopy reveals that stalks are composed of several fibrils, which contain few-nanometer-sized iron oxyhydroxide crystals. Lepidocrocite crystals that nucleated on the fibril surface are much larger (∼100  nm), suggesting that mineral growth within fibrils is retarded, relative to sites surrounding fibrils. C and N 1s NEXAFS spectroscopy and fluorescence probing show that stalks primarily contain carboxyl-rich polysaccharides. On the basis of these results, we suggest a physiological model for Fe oxidation in which cells excrete oxidized Fe bound to organic polymers. These organic molecules retard mineral growth, preventing cell encrustation. This model describes an essential role for stalk formation in FeOB growth. We suggest that stalk-like morphologies observed in modern and ancient samples may be correlated confidently with the Fe-oxidizing metabolism as a robust biosignature.

  13. Lithotrophic iron-oxidizing bacteria produce organic stalks to control mineral growth: implications for biosignature formation

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Clara S; Fakra, Sirine C; Emerson, David; Fleming, Emily J; Edwards, Katrina J

    2011-07-01

    Neutrophilic Fe-oxidizing bacteria (FeOB) are often identified by their distinctive morphologies, such as the extracellular twisted ribbon-like stalks formed by Gallionella ferruginea or Mariprofundus ferrooxydans. Similar filaments preserved in silica are often identified as FeOB fossils in rocks. Although it is assumed that twisted iron stalks are indicative of FeOB, the stalk's metabolic role has not been established. To this end, we studied the marine FeOB M. ferrooxydans by light, X-ray and electron microscopy. Using time-lapse light microscopy, we observed cells excreting stalks during growth (averaging 2.2 {micro}m h(-1)). Scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy show that stalks are Fe(III)-rich, whereas cells are low in Fe. Transmission electron microscopy reveals that stalks are composed of several fibrils, which contain few-nanometer-sized iron oxyhydroxide crystals. Lepidocrocite crystals that nucleated on the fibril surface are much larger ({approx}100 nm), suggesting that mineral growth within fibrils is retarded, relative to sites surrounding fibrils. C and N 1s NEXAFS spectroscopy and fluorescence probing show that stalks primarily contain carboxyl-rich polysaccharides. On the basis of these results, we suggest a physiological model for Fe oxidation in which cells excrete oxidized Fe bound to organic polymers. These organic molecules retard mineral growth, preventing cell encrustation. This model describes an essential role for stalk formation in FeOB growth. We suggest that stalk-like morphologies observed in modern and ancient samples may be correlated confidently with the Fe-oxidizing metabolism as a robust biosignature.

  14. Methodological aspects of breath hydrogen (H2) analysis. Evaluation of a H2 monitor and interpretation of the breath H2 test

    DEFF Research Database (Denmark)

    Rumessen, J J; Kokholm, G; Gudmand-Høyer, E

    1987-01-01

    The reliability of end-expiratory hydrogen (H2) breath tests were assessed and the significance of some important pitfalls were studied, using a compact, rapid H2-monitor with electrochemical cells. The H2 response was shown to be linear and stable. The reproducibility of the breath collection...... were studied in 10 healthy adults during a 4-month period and they showed very marked inter- and intra-individual variability (16% above 40 p.p.m.). Initial peaks (early, short-lived H2 rises unrelated to carbohydrate malabsorption) were identified in 25% of the breath tests (in 4% above 20 p.......p.m). It is concluded that the technique used for interval sampling of end-expiratory breath samples for H2 concentration gives reliable results. The biological significance of H2 concentration increments can only be evaluated if the limitations of the technical procedures and the individual ability to produce H2...

  15. Production of conjugated linoleic acid (CLA) by Bifidobacterium breve LMC520 and its compatibility with CLA-producing rumen bacteria.

    Science.gov (United States)

    Park, Hui Gyu; Heo, Wan; Kim, Sang Bum; Kim, Hyun Seop; Bae, Gui Seck; Chung, Soo Hyun; Seo, Ho-Chan; Kim, Young Jun

    2011-02-09

    This study was performed to characterize the ability of an active Bifidobacterium strain to produce conjugated linoleic acid (CLA) and to test its possible utilization as a probiotic compatible to the ruminal condition. Bifidobacterium breve LMC520 can actively convert linoleic acid (LA) to cis-9,trans-11-CLA, which is a major isomer derived from microbial conversion. LMC520 showed reasonable tolerance under acidic conditions (pH 2.5 with 1% pepsin) and in the presence of oxgall (0-3%). The growth and CLA production of LMC520 were tested under ruminal conditions and compared with those of Butyrivibrio fibrisolvens A38, which is a major CLA producer in the rumen as an intermediate in the biohydrogenation (BH) process. LMC520 converted 15% of LA to CLA under ruminal conditions, which was 2 times higher activity than that of A38, and there was no decline in CLA level during prolonged incubation of 48 h. The BH activity of LMC520 was comparable to that of A38. When LMC520 was cocultured with A38, even with slight decrease of CLA due to high BH activity by A38, but the level of CLA was maintained by the high CLA-producing activity of LMC520. This comparative study shows the potential of this strain to be applied as a functional probiotic not only for humans but also for ruminants as well as to increase CLA production.

  16. Gluconacetobacter medellinensis sp. nov., cellulose- and non-cellulose-producing acetic acid bacteria isolated from vinegar.

    Science.gov (United States)

    Castro, Cristina; Cleenwerck, Ilse; Trcek, Janja; Zuluaga, Robin; De Vos, Paul; Caro, Gloria; Aguirre, Ricardo; Putaux, Jean-Luc; Gañán, Piedad

    2013-03-01

    The phylogenetic position of a cellulose-producing acetic acid bacterium, strain ID13488, isolated from commercially available Colombian homemade fruit vinegar, was investigated. Analyses using nearly complete 16S rRNA gene sequences, nearly complete 16S-23S rRNA gene internal transcribed spacer (ITS) sequences, as well as concatenated partial sequences of the housekeeping genes dnaK, groEL and rpoB, allocated the micro-organism to the genus Gluconacetobacter, and more precisely to the Gluconacetobacter xylinus group. Moreover, the data suggested that the micro-organism belongs to a novel species in this genus, together with LMG 1693(T), a non-cellulose-producing strain isolated from vinegar by Kondo and previously classified as a strain of Gluconacetobacter xylinus. DNA-DNA hybridizations confirmed this finding, revealing a DNA-DNA relatedness value of 81 % between strains ID13488 and LMG 1693(T), and values <70 % between strain LMG 1693(T) and the type strains of the closest phylogenetic neighbours. Additionally, the classification of strains ID13488 and LMG 1693(T) into a single novel species was supported by amplified fragment length polymorphism (AFLP) and (GTG)5-PCR DNA fingerprinting data, as well as by phenotypic data. Strains ID13488 and LMG 1693(T) could be differentiated from closely related species of the genus Gluconacetobacter by their ability to produce 2- and 5-keto-d-gluconic acid from d-glucose, their ability to produce acid from sucrose, but not from 1-propanol, and their ability to grow on 3 % ethanol in the absence of acetic acid and on ethanol, d-ribose, d-xylose, sucrose, sorbitol, d-mannitol and d-gluconate as carbon sources. The DNA G+C content of strains ID13488 and LMG 1693(T) was 58.0 and 60.7 mol%, respectively. The major ubiquinone of LMG 1693(T) was Q-10. Taken together these data indicate that strains ID13488 and LMG 1693(T) represent a novel species of the genus Gluconacetobacter for which the name Gluconacetobacter

  17. Screening for exopolysaccharide-producing bacteria from sub-tropical polluted groundwater

    Directory of Open Access Journals (Sweden)

    R. FUSCONI

    Full Text Available A selection of exopolysaccharide (EPS -- producing bacterial strains was conducted in groundwater adjacent to an old controlled landfill in the City of São Carlos (São Paulo, Brazil. The strains were isolated in P and E media under aerobic and microaerophilic conditions at 25ºC. A total of 26 strains were isolated and based on the mucoid mode of the colonies, 6 were selected and their morphological, physiological and biochemical aspects were characterized. All strains presented pigmentation, ranging from yellow to orange and from pink to salmon, with a shiny glistening aspect in all tested media. Strains Lb, Lc and Lg, which excelled the others with regard to the mucoid mode of the colonies, were selected to be cultured in E medium with alternate sucrose and glucose as carbon sources in anaerobiosis at 25ºC to analyze the production of EPS. Strains Lc and Lg were classified as being of order Actinomycelates, suborder Corynebacterineae. Lg strain was identified as Gordonia polyisoprenivorans and Lc strain did not correspond to a known description and therefore a more detailed study is under preparation. Considering all ecological aspects and the metabolic potential associated with the microorganisms of the environment studied, as well as the capacity to produce pigment and EPS, and the presence of G. polyisoprenivorans, a rubber degrader bacterium, the potential of the groundwater analyzed is evident as a source of microorganisms to be utilized in studies related to environmental remediation.

  18. Isolation of biosurfactant producing bacteria from petroleum contaminated sites and their characterization

    Directory of Open Access Journals (Sweden)

    Rida Batool

    2017-05-01

    Full Text Available Biosurfactants are microbial amphiphilic compounds which can reduce surface tension between aqueous and hydrocarbon mixtures. Bacterial strains isolated from petroleum contaminated soil of various motor workshops were characterized morphologically and biochemically. Biosurfactant producing ability of the strains was determined and their emulsification activity was screened against different oils. All the selected bacterial strains showed enhanced biosurfactants production with yeast extract as nitrogen source and glucose as carbon source at optimized conditions. These strains also exhibited multiple metal and antibiotics resistance. Isolated biosurfactants of three most promising strains SF-1, SF-4 and SM-1 were extracted by solvent extraction and subjected to TLC technique. The technique indicates the glycolipid nature of the compounds and presence of rhamnose sugar, which was further confirmed by FT-IR analysis. 16srRNA analysis revealed that SF-1 and SM-1 had close resemblance with Pseudomonas sp. while SF-4 showed homology with Enterobacter sp. Isolation and screening of biosurfactant producing strains from petroleum polluted places proved to be a quick and effective means to find bacterial strains with possible industrial uses.

  19. Production, optimization and probiotic characterization of potential lactic acid bacteria producing siderophores

    Directory of Open Access Journals (Sweden)

    Smita H. Panda

    2017-02-01

    Full Text Available The aim of the study was to characterize the probiotic qualities and siderophore production of Enterococcus and Bacillus isolates for possible application for iron nutrition in human and animals strains were selectively isolated from different dairy sources and infant faecal matter. Isolates SB10, JC13 and IFM22 were found to produce maximum siderophore ranging from 65–90% at an optimum pH 7, incubation period of 96 h, agitation speed of 150 rpm and inoculum volume of 15%. SB10 and JC13 were found to show high homology with Enterococcus spp. and IFM22 with Bacillus spp., using partial 16S rRNA sequencing and biochemical characterization. All the three isolates produced hydroxymate type of siderophores under iron stressed conditions and screened for probiotic characters as per WHO guidelines. Strains have shown excellent tolerance to acid, bile salt, sodium chloride and phenol. They were non-haemolytic in nature and exhibited high hydrophobicity and autoaggregation. Our isolates proved to be potent probiotic strains due to their survival under highly acidic conditions and higher tolerance to bile salt. In addition, its colonization efficiency was proved by exhibiting high autoaggregation and hydrophobicity.

  20. Selection of biosurfactan/bioemulsifier-producing bacteria from hydrocarbon-contaminated soil

    Directory of Open Access Journals (Sweden)

    Sabina Viramontes-Ramos

    2010-10-01

    Full Text Available Petroleum-derived hydrocarbons are among the most persistent soil contaminants, and some hydrocarbon-degrading microorganisms can produce biosurfactants to increase bioavailability and degradation. The aim of this work was to identify biosurfactant-producing bacterial strains isolated from hydrocarbon-contaminated sites, and to evaluate their biosurfactant properties. The drop-collapse method and minimal agar added with a layer of combustoleo were used for screening, and positive strains were grown in liquid medium, and surface tension and emulsification index were determined in cell-free supernantant and cell suspension. A total of 324 bacterial strains were tested, and 17 were positive for the drop-collapse and hydrocarbon-layer agar methods. Most of the strains were Pseudomonas, except for three strains (Acinetobacter, Bacillus, Rhodococcus. Surface tension was similar in cell-free and cell suspension measurements, with values in the range of 58 to 26 (mN/m, and all formed stable emulsions with motor oil (76-93% E24. Considering the variety of molecular structures among microbial biosurfactants, they have different chemical properties that can be exploited commercially, for applications as diverse as bioremediation or degradable detergents.

  1. Isolation, screening and production studies of uricase producing bacteria from poultry sources.

    Science.gov (United States)

    Nanda, Pooja; Babu, P E Jagadeesh

    2014-01-01

    Uricase (urate oxidase EC 1.7.3.3) is a therapeutic enzyme that is widely used to catalyze the enzymatic oxidation of uric acid in the treatment of hyperuricemia and gout diseases. In this study, three bacterial species capable of producing extracellular uricase were isolated from a poultry source and screened based on the size of the clear zone using a uric acid agar plate. The bacterial species capable of producing uricase with the highest uricolytic activity was identified as Bacillus cereus strain DL3 using a 16SrRNA gene sequencing approach. The time-course study of uricase production was performed and the medium was optimized. Carboxymethylcellulose and asparagine were found to be the best carbon and nitrogen sources. Maximum uricolytic activity was observed at pH 7.0 with an inducer concentration of 2.0 g/L. Inoculum size of 5% gave maximum uricolytic activity. The maximum uricolytic activity of 15.43 U/mL was achieved at optimized conditions, which is 1.61 times more than the initial activity. Further, enzymatic stability was determined at different pH and temperature.

  2. Isolation, screening and characterization of bacteriocin-producing lactic acid bacteria isolated from traditional fermented food.

    Science.gov (United States)

    El-Shafei, H A; Abd-El-Sabour, H; Ibrahim, N; Mostafa, Y A

    2000-03-01

    100 lactic acid bacterial strains isolated from traditional fermented foods (yoghurt, milk cream, sour dough and milk) were screened for bacteriocin production. Twenty six strains producing a nisin-like bacteriocin were selected. Most of these isolates gave only a narrow inhibitory spectrum, although one showed a broad inhibitory spectrum against the indicator strains tested, this strain was determined as Lactococcus lactis. The influence of several parameters on the fermentative production of nisin by Lactococcus lactis was studied. Production of nisin was optimal at 30 degrees C and in the pH range 5.5-6.3. The effect of different sulphur and nitrogen sources on Lactococcus lactis growth and nisin production was studied. Magnesium sulfate and manganese sulfate were found to be the best sulphur sources while triammonium citrate was the best inorganic nitrogen source and meat extract, peptone and yeast extract were the best organic nitrogen source for nisin production.

  3. Construction and screening of a functional metagenomic library to identify novel enzymes produced by Antarctic bacteria

    Institute of Scientific and Technical Information of China (English)

    Ignacio Ferrés; Vanesa Amarelle; Francisco Noya; Elena Fabiano

    2015-01-01

    A metagenomic fosmid library of approximately 52 000 clones was constructed to identify functional genes encoding cold-adapted enzymes. Metagenomic DNA was extracted from a sample of glacial meltwater, collected on the Antarctic Peninsula during the ANTARKOS XXIX Expedition during the austral summer of 2012–2013. Each clone contained an insert of about 35–40 kb, so the library represented almost 2 Gb of genetic information from metagenomic DNA. Activity-driven screening was used to detect the cold-adapted functions expressed by the library. Fifty lipase/esterase and two cellulase-producing clones were isolated, and two clones able to grow on Avicel® as the sole carbon source. Interestingly, three clones formed a brown precipitate in the presence of manganese (II). Accumulation of manganese oxides was determined with a leucoberbelin blue assay, indicating that these three clones had manganese-oxidizing activity. To the best of our knowledge, this is the first report of a manganese oxidase activity detected with a functional metagenomic strategy.

  4. In vitro activity of plant extracts against biofilm-producing food-related bacteria.

    Science.gov (United States)

    Nostro, Antonia; Guerrini, Alessandra; Marino, Andreana; Tacchini, Massimo; Di Giulio, Mara; Grandini, Alessandro; Akin, Methap; Cellini, Luigina; Bisignano, Giuseppe; Saraçoğlu, Hatice T

    2016-12-05

    The identification of effective antimicrobial agents also active on biofilms is a topic of crucial importance in food and industrial environment. For that purpose methanol extracts of Turkish plants, Ficus carica L., Juglans regia L., Olea europaea L., Punica granatum L. and Rhus coriaria L., were investigated. Among the extracts, P. granatum L. and R. coriaria L. showed the best antibacterial activity with minimum inhibitory concentrations (MIC) of 78-625μg/ml for Listeria monocytogenes and Staphylococcus aureus and 312-1250μg/ml for Escherichia coli and Pseudomonas aeruginosa. SubMICs produced a significant biofilm inhibition equal to 80-60% for L. monocytogenes and 90-80% for S. aureus. The extracts showed also the highest polyphenol content and the strongest antioxidant activity. Bioassay-guided and HPLC procedures demonstrated the presence of apigenin 4'-O-β-glucoside in P. granatum L. and myricetrin and quercitrin in R. coriaria L. Antigenotoxicity of plant extracts was also observed The present findings promote the value-adding of P. granatum L. and R. coriaria L. leaves as natural antimicrobial/antioxidant agents for control of food-related bacterial biofilms.

  5. Antioxidant activity of pea protein hydrolysates produced by batch fermentation with lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Stanisavljević Nemanja S.

    2015-01-01

    Full Text Available Nine Lactobacillus strains known for surface proteinase activity were chosen from our collection and tested for their ability to grow in pea seed protein-based medium, and to hydrolyze purified pea proteins in order to produce peptides with antioxidant (AO activity. Two strains, Lactobacillus rhamnosus BGT10 and Lactobacillus zeae LMG17315, exhibited strong proteolytic activity against pea proteins. The AO activity of the pea hydrolysate fraction, MW <10 kDa, obtained by the fermentation of purified pea proteins with Lactobacillus rhamnosus BGT10, was tested by standard spectrophotometric assays (DPPH, ABTS, Fe3+-reducing capacity and the recently developed direct current (DC polarographic assay. The low molecular weight fraction of the obtained hydrolysate was separated using ion exchange chromatography, while the AO activity of eluted fractions was determined by means of a sensitive DC polarographic assay without previous concentration of samples. Results revealed that the fraction present in low abundance that contained basic peptides possessed the highest antioxidant activity. Based on the obtained results, it can be concluded that Lactobacillus rhamnosus BGT10 should be further investigated as a candidate strain for large-scale production of bioactive peptides from legume proteins. [Projekat Ministartsva nauke Republike Srbije, br. 173005 i br. 173026

  6. Phenotypic and genotypic characteristics of enterocin producing enterococci against pathogenic bacteria

    Directory of Open Access Journals (Sweden)

    Sandra Mojsova

    2015-10-01

    Full Text Available The study investigated the antimicrobial activity of 13 enterococcal strains (E. faecalis -8, E. faecium-2, E. hirae-2, E. spp.-1 isolated from our traditional cheeses against pathogen microorganisms. Also, it includes the detection of the following enterocin structural genes: enterocin A, enterocin B, enterocin P, enterocin L50A/B, bacteriocin 31, enterocin AS48, enterocin Q, enterocin EJ97 and cytolysin by using PCR method. All isolates inhibited growth of L. monocytogenes and L.innocua. One isolate had a broader antimicrobial activity. None of the isolates showed inhibitory activity against S. enteritidis, E. coli and Y. enterocolitica. The genes enterocin P, cytolysin and enterocin A were the most frequently detected structural genes among the PCR positive strains. No amplification was obtained in two strains E. faecalis-25 and E. faecalis-86. Three different genes were identified in some strains. With the exclusion of strains possessing a virulence factor, such as cytolysin, producers of more than one enterocins could be of a great technological potential as protective cultures in the cheese industry.

  7. Identification of the Antibacterial Compound Produced by the Marine Epiphytic Bacterium Pseudovibrio sp. D323 and Related Sponge-Associated Bacteria

    Directory of Open Access Journals (Sweden)

    Suhelen Egan

    2011-08-01

    Full Text Available Surface-associated marine bacteria often produce secondary metabolites with antagonistic activities. In this study, tropodithietic acid (TDA was identified to be responsible for the antibacterial activity of the marine epiphytic bacterium Pseudovibrio sp. D323 and related strains. Phenol was also produced by these bacteria but was not directly related to the antibacterial activity. TDA was shown to effectively inhibit a range of marine bacteria from various phylogenetic groups. However TDA-producers themselves were resistant and are likely to possess resistance mechanism preventing autoinhibition. We propose that TDA in isolate D323 and related eukaryote-associated bacteria plays a role in defending the host organism against unwanted microbial colonisation and, possibly, bacterial pathogens.

  8. BIOCHEMICAL CHARACTERISTICS OF LACTIC ACID PRODUCING BACTERIA AND PREPARATION OF CAMEL MILK CHEESE BY USING STARTER CULTURE

    Directory of Open Access Journals (Sweden)

    T. Ahmed and R. Kanwal

    2004-04-01

    Full Text Available Lactic acid bacteria (LAB were isolated from camel milk by culturing the milk on specific media and pure culture was obtained by sub-culturing. Purification of culture was confirmed by Gram’s staining and identified by different biochemical tests. Camel milk contained lactic acid producing bacteria like Streptococci such as S. cremoris and S. lactis and Lactobacilli such as L. acidophilus. L. acidophilus grew more rapidly in camel milk than others as its growth was supported by camel milk. Ability of each strain was tested to convert lactose of milk into lactic acid. It was observed that 66% lactose was converted by S. lactis 20, whereas S. cremoris 22 and L. acidophilus 23 converted 56 and 74% lactose into lactic acid, respectively. Effect of freeze-drying was also recorded and the results showed that in all cases there was a slight decrease in the cell count before and after the freeze-drying. The decrease was approximately 0.47, 0.078 and 0.86% for S. lactis 20, S. cremoris 22 and L. acidophilus 23, respectively. Starter culture was prepared from strains isolated from camel milk. Camel and buffalo milk cheese was prepared by using starter culture. The strains isolated from camel milk were best for acid production and coagulated the milk in less time. It is concluded that cheese can be prepared successfully from camel milk and better results can be obtained by coagulating milk with starter culture.

  9. Characterisation of volatile compounds produced by bacteria isolated from the spoilage flora of cold-smoked salmon.

    Science.gov (United States)

    Joffraud, J J; Leroi, F; Roy, C; Berdagué, J L

    2001-06-15

    This study investigated the volatile compounds produced by bacteria belonging to nine different bacterial groups: Lactobacillus sake, L. farciminis, L. alimentarius, Carnobacterium piscicola, Aeromonas sp., Shewanella putrefaciens, Brochothrix thermosphacta, Photobacterium phosphoreum and Enterobacteriaceae isolated from cold-smoked salmon. Each bacterial group was represented by several strains. In addition, combinations of the groups were examined as well. Sterile blocks of cold-smoked salmon were inoculated, vacuum-packed and stored at 6 degrees C. After 40 days of storage at 6 degrees C, aerobic viable count and pH were recorded, the volatile fraction of the samples was analysed by gas chromatography-mass spectrometry (GC-MS), and spoilage was assessed by sensory evaluation. Among the 81 volatile compounds identified by GC-MS, 30 appeared to be released as a result of bacterial metabolism. Some of the effects of inoculated bacterial strains on the composition of the volatile fraction seemed to be characteristic of certain bacterial species. Sensory analysis showed relationships between bacteria, the composition of the volatile fraction and the organoleptic quality of smoked salmon.

  10. Cultivation of a chemoautotroph from the SUP05 clade of marine bacteria that produces nitrite and consumes ammonium

    Science.gov (United States)

    Shah, Vega; Chang, Bonnie X; Morris, Robert M

    2017-01-01

    Marine oxygen minimum zones (OMZs) are expanding regions of intense nitrogen cycling. Up to half of the nitrogen available for marine organisms is removed from the ocean in these regions. Metagenomic studies have identified an abundant group of sulfur-oxidizing bacteria (SUP05) with the genetic potential for nitrogen cycling and loss in OMZs. However, SUP05 have defied cultivation and their physiology remains untested. We cultured, sequenced and tested the physiology of an isolate from the SUP05 clade. We describe a facultatively anaerobic sulfur-oxidizing chemolithoautotroph that produces nitrite and consumes ammonium under anaerobic conditions. Genetic evidence that closely related strains are abundant at nitrite maxima in OMZs suggests that sulfur-oxidizing chemoautotrophs from the SUP05 clade are a potential source of nitrite, fueling competing nitrogen removal processes in the ocean. PMID:27434424

  11. Comparative analysis of production and purification of homo- and hetero-polysaccharides produced by lactic acid bacteria.

    Science.gov (United States)

    Notararigo, Sara; Nácher-Vázquez, Montserrat; Ibarburu, Idoia; Werning, Ma Laura; de Palencia, Pilar Fernández; Dueñas, Ma Teresa; Aznar, Rosa; López, Paloma; Prieto, Alicia

    2013-03-01

    Lactic acid bacteria (LAB) produce homopolysaccharides (HoPS) and heteropolysaccharides (HePS) with potential functional properties. In this work, we have performed a comparative analysis of production and purification trials of these biopolymers from bacterial culture supernatants. LAB strains belonging to four different genera, both natural as well as recombinant, were used as model systems for the production of HoPS and HePS. Two well characterized strains carrying the gft gene were used for β-glucan production, Pediococcus parvulus 2.6 (P. parvulus 2.6) isolated from cider, and the recombinant strain Lactococcus lactis NZ9000[pGTF] (L. lactis NZ9000[pGTF]). In addition, another cider isolate, Lactobacillus suebicus CUPV225 (L. suebicus CUPV225), and Leuconostoc mesenteroides RTF10 (L. mesenteroides RTF10), isolated from meat products were included in the study. Chemical analysis of the EPS revealed that L. mesenteroides produces a dextran, L. suebicus a complex heteropolysaccharide, and the β-glucan producing-strains the expected 2-substituted (1,3)-β-glucan. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Potential of bacteriocin-producing lactic acid bacteria for safety improvements of traditional Thai fermented meat and human health.

    Science.gov (United States)

    Swetwiwathana, Adisorn; Visessanguan, Wonnop

    2015-11-01

    Lactic acid bacteria (LAB) are very important in converting of agricultural products into safe, delicious and shelf stable foods for human consumption. The preservative activity of LAB in foods is mainly attributed to the production of anti-microbial metabolites such as organic acids and bacteriocins which enables them to grow and control the growth of pathogens and spoilage microorganisms. Besides ensuring safety, bacteriocin-producing LAB with their probiotic potentials could also be emerging as a means to develop functional meat products with desirable health benefits. Nevertheless, to be qualified as a candidate probiotic culture, other prerequisite probiotic properties of bacteriocin-producing LAB have to be assessed according to regulatory guidelines for probiotics. Nham is an indigenous fermented sausage of Thailand that has gained popularity and acceptance among Thais. Since Nham is made from raw meat and is usually consumed without cooking, risks due to undesirable microorganisms such as Salmonella spp., Staphylococcus aureus, and Listeria monocytogenes, are frequently observed. With an ultimate goal to produce safer and healthier product, our research attempts on the development of a variety of new Nham products are discussed.

  13. Anodic biofilms in microbial fuel cells harbor low numbers of higher-power-producing bacteria than abundant genera

    Energy Technology Data Exchange (ETDEWEB)

    Kiely, Patrick D.; Call, Douglas F.; Yates, Matthew D.; Regan, John M.; Logan, Bruce E. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Civil and Environmental Engineering

    2010-09-15

    Microbial fuel cell (MFC) anode communities often reveal just a few genera, but it is not known to what extent less abundant bacteria could be important for improving performance. We examined the microbial community in an MFC fed with formic acid for more than 1 year and determined using 16S rRNA gene cloning and fluorescent in situ hybridization that members of the Paracoccus genus comprised most ({proportional_to}30%) of the anode community. A Paracoccus isolate obtained from this biofilm (Paracoccus denitrificans strain PS-1) produced only 5.6 mW/m{sup 2}, whereas the original mixed culture produced up to 10 mW/m{sup 2}. Despite the absence of any Shewanella species in the clone library, we isolated a strain of Shewanella putrefaciens (strain PS-2) from the same biofilm capable of producing a higher-power density (17.4 mW/m{sup 2}) than the mixed culture, although voltage generation was variable. Our results suggest that the numerical abundance of microorganisms in biofilms cannot be assumed a priori to correlate to capacities of these predominant species for high-power production. Detailed screening of bacterial biofilms may therefore be needed to identify important strains capable of high-power generation for specific substrates. (orig.)

  14. Anodic biofilms in microbial fuel cells harbor low numbers of higher-power-producing bacteria than abundant genera

    KAUST Repository

    Kiely, Patrick D.

    2010-07-15

    Microbial fuel cell (MFC) anode communities often reveal just a few genera, but it is not known to what extent less abundant bacteria could be important for improving performance. We examined the microbial community in an MFC fed with formic acid for more than 1 year and determined using 16S rRNA gene cloning and fluorescent in situ hybridization that members of the Paracoccus genus comprised most (~30%) of the anode community. A Paracoccus isolate obtained from this biofilm (Paracoccus denitrificans strain PS-1) produced only 5.6 mW/m 2, whereas the original mixed culture produced up to 10 mW/m 2. Despite the absence of any Shewanella species in the clone library, we isolated a strain of Shewanella putrefaciens (strain PS-2) from the same biofilm capable of producing a higher-power density (17.4 mW/m2) than the mixed culture, although voltage generation was variable. Our results suggest that the numerical abundance of microorganisms in biofilms cannot be assumed a priori to correlate to capacities of these predominant species for high-power production. Detailed screening of bacterial biofilms may therefore be needed to identify important strains capable of high-power generation for specific substrates. © 2010 Springer-Verlag.

  15. Inhibition of food-related bacteria by antibacterial substances produced by Pseudomonas sp. strains isolated from pasteurized milk

    Directory of Open Access Journals (Sweden)

    Ana Beatriz Ferreira Rangel

    2013-12-01

    Full Text Available In this work, the production of antimicrobial substances by strains of Pseudomonas sp. isolated from pasteurized milk and their potential action against food-related bacteria were investigated. Samples of pasteurized milk were purchased from arbitrarily chosen commercial establishments in the city of Rio de Janeiro, Brazil. Of the four samples analyzed, three presented several typical colonies of Pseudomonas. About 100 colonies were chosen and subjected to biochemical tests for confirmation of their identity. Eighteen strains of the Pseudomonas genus were identified and submitted to tests for the production of antimicrobial substances. Twelve strains (66.7% were identified as Pseudomonas fluorescens, four (22.2% as P. aeruginosa, one (5.5% as P. mendocina and one (5.5% as P. pseudoalcaligenes. Only two P. fluorescens strains were unable to produce any antimicrobial substance against any of the indicator strains tested. Most of the strains presented a broad spectrum of action, inhibiting reference and food-related strains such as Proteus vulgaris, Proteus mirabilis, Hafnia alvei, Yersinia enterocolitica, Escherichia coli and Salmonella typhi. Five antimicrobial substance-producing strains, which presented the broadest spectrum of action, were also tested against Staphylococcus aureus reference strains and 26 Staphylococcus sp. strains isolated from foods, some of which were resistant to antibiotics. The producer strains 8.1 and 8.3, both P. aeruginosa, were able to inhibit all the staphylococcal strains tested. The antimicrobial substances produced by strains 8.1 and 8.3 did not seem to be typical bacteriocins, since they were resistant to the three proteolytic enzymes tested. Experiments involving the characterization of these substances are being carried out in order to evaluate their biotechnological application.

  16. Alternative rooting induction of semi-hardwood olive cuttings by several auxin-producing bacteria for organic agriculture systems

    Directory of Open Access Journals (Sweden)

    M. C. Montero-Calasanz

    2013-01-01

    Full Text Available Southern Spain is the largest olive oil producer region in the world. In recent years organic agriculture systems have grown exponentially so that new alternative systems to produce organic olive cuttings are needed. Several bacterial isolates, namely Pantoea sp. AG9, Chryseobacterium sp. AG13, Chryseobacterium sp. CT348, Pseudomonas sp. CT364 and Azospirillum brasilense Cd (ATCC 29729, have been used to induce rooting in olive semi-hardwood cuttings of Arbequina, Hojiblanca and Picual cultivars of olive (Olea europea L. The first four strains were previously selected as auxin-producing bacteria and by their ability to promote rooting in model plants. They have been classified on the basis of their 16S rDNA gene sequence. The known auxin producer A. brasilense Cd strain has been used as a reference. The inoculation of olive cuttings was performed in two different ways: (i by dipping cuttings in a liquid bacterial culture or (ii by immersing them in a paste made of solid bacterial inoculant and sterile water. Under nursery conditions all of the tested bacterial strains were able to induce the rooting of olive cuttings to a similar or greater extent than the control cuttings treated with indole-3-butyric acid (IBA. The olive cultivars responded differently depending on the bacterial strain and the inoculation method. The strain that consistently gave the best results was Pantoea sp. AG9, the only one of the tested bacterial strains to express the enzyme 1-aminocyclopropane-1-carboxylate (ACC deaminase. The results are also discussed in terms of potential commercial interest and nursery feasibility performance of these strains.

  17. Prebiotic Content of Bread Prepared with Flour from Immature Wheat Grain and Selected Dextran-Producing Lactic Acid Bacteria

    Science.gov (United States)

    Ventorino, Valeria; Cavella, Silvana; Fagnano, Massimo; Brugno, Rachele

    2013-01-01

    In the last few years the need to produce food with added value has fueled the search for new ingredients and health-promoting compounds. In particular, to improve the quality of bakery products with distinct nutritional properties, the identification of new raw materials, appropriate technologies, and specific microbial strains is necessary. In this study, different doughs were prepared, with 10% and 20% flour from immature wheat grain blended with type “0 America” wheat flour. Immature flour was obtained from durum wheat grains harvested 1 to 2 weeks after anthesis. Doughs were obtained by both the straight-dough and sourdough processes. Two selected exopolysaccharide-producing strains of lactic acid bacteria (LAB), Leuconostoc lactis A95 and Lactobacillus curvatus 69B2, were used as starters. Immature flour contained 2.21 g/100 g (dry weight) of fructo-oligosaccharides. Twenty percent immature flour in dough resulted in a shorter leavening time (4.23 ± 0.03 h) than with the control and dough with 10% immature flour. The total titratable acidity of sourdough with 20% immature flour was higher (12.75 ± 0.15 ml 0.1 N NaOH) than in the control and sourdough with 10% immature wheat flour (9.20 ml 0.1 N NaOH). Molecular analysis showed that all samples contained three LAB species identified as L. lactis, L. curvatus, and Pediococcus acidilactici. A larger amount of exopolysaccharide was found in sourdough obtained with 20% immature flour (5.33 ± 0.032 g/kg), positively influencing the exopolysaccharide content of the bread prepared by the sourdough process (1.70 ± 0.03 g/kg). The addition of 20% immature flour also led to a greater presence of fructo-oligosaccharides in the bread (900 mg/100 g dry weight), which improved its nutritional characteristics. While bread volume decreased as the concentration of immature wheat flour increased, its mechanical characteristics (stress at a strain of 30%) were the same in all samples obtained with different percentages

  18. Prebiotic content of bread prepared with flour from immature wheat grain and selected dextran-producing lactic acid bacteria.

    Science.gov (United States)

    Pepe, Olimpia; Ventorino, Valeria; Cavella, Silvana; Fagnano, Massimo; Brugno, Rachele

    2013-06-01

    In the last few years the need to produce food with added value has fueled the search for new ingredients and health-promoting compounds. In particular, to improve the quality of bakery products with distinct nutritional properties, the identification of new raw materials, appropriate technologies, and specific microbial strains is necessary. In this study, different doughs were prepared, with 10% and 20% flour from immature wheat grain blended with type "0 America" wheat flour. Immature flour was obtained from durum wheat grains harvested 1 to 2 weeks after anthesis. Doughs were obtained by both the straight-dough and sourdough processes. Two selected exopolysaccharide-producing strains of lactic acid bacteria (LAB), Leuconostoc lactis A95 and Lactobacillus curvatus 69B2, were used as starters. Immature flour contained 2.21 g/100 g (dry weight) of fructo-oligosaccharides. Twenty percent immature flour in dough resulted in a shorter leavening time (4.23 ± 0.03 h) than with the control and dough with 10% immature flour. The total titratable acidity of sourdough with 20% immature flour was higher (12.75 ± 0.15 ml 0.1 N NaOH) than in the control and sourdough with 10% immature wheat flour (9.20 ml 0.1 N NaOH). Molecular analysis showed that all samples contained three LAB species identified as L. lactis, L. curvatus, and Pediococcus acidilactici. A larger amount of exopolysaccharide was found in sourdough obtained with 20% immature flour (5.33 ± 0.032 g/kg), positively influencing the exopolysaccharide content of the bread prepared by the sourdough process (1.70 ± 0.03 g/kg). The addition of 20% immature flour also led to a greater presence of fructo-oligosaccharides in the bread (900 mg/100 g dry weight), which improved its nutritional characteristics. While bread volume decreased as the concentration of immature wheat flour increased, its mechanical characteristics (stress at a strain of 30%) were the same in all samples obtained with different percentages of

  19. A Proof of Concept Study to Detect Urease Producing Bacteria in Lungs Using Aerosolized 13C-Urea

    Science.gov (United States)

    Timmins, Graham; Davies, Lea; Heynekamp, Theresa; Harkins, Michelle; Sharp, Zachary D.; Kelly, H. William

    2016-01-01

    This is a “proof of concept” study to determine whether inhalation of 13C-urea can be safely used to detect the presence of urease producing bacteria in the airways of patients with cystic fibrosis (CF) by detecting 13CO2 in breath. This was a prospective, 2-part, open label, single-center, single-arm, single-administration, dose-escalation investigational device exemption trial. First, the safety of 20 and 50 mg inhaled 13C-urea was evaluated in 6 healthy adult participants. Then, 3 adult CF participants colonized with Pseudomonas aeruginosa were enrolled for each dose of inhaled 13C-urea. The safety of inhaled 13C-urea was assessed by spirometry and physical examination. 13C-urea was administered using a jet nebulizer, followed by serial spirometry (10 min and 30 min post inhalation) and collection of exhaled breath at 5, 10, and 15 min post inhalation. There was no clinical significant change in any of the spirometry values compared to baseline in healthy participants and CF patients. Mean of 13CO2/12CO2 delta over baseline (DOB) values in CF participants at 5, 10, and 15 min post inhalation was as follows: 20 mg dose 4‰ (2.2‰–4.9‰), 1‰ (1.0‰–1.4‰), and 1‰ (0.4‰–1.5‰); 50 mg dose: 10‰ (6.2‰–14.5‰), 3‰ (2.1‰–4.3‰), and 1.5‰ (0.6‰–2.3‰). Inhaled 13C-urea for detection of urease producing bacteria was safe, and preliminary data suggest that 13CO2/12CO2 DOB values may be higher in CF patients with P. aeruginosa at 5–10 min after inhalation of 13C-urea. A future direction is to investigate use of inhaled 13C-urea in young children who have difficulty producing sputum for culturing. PMID:27458537

  20. Phytase-Producing Potential and Other Functional Attributes of Lactic Acid Bacteria Isolates for Prospective Probiotic Applications.

    Science.gov (United States)

    Andrabi, Syed Tabia; Bhat, Bilqeesa; Gupta, Mahak; Bajaj, Bijender Kumar

    2016-09-01

    Wide variations among multifaceted-health benefitting attributes of probiotics fueled investigations on targeting efficacious probiotics. In the current study, lactic acid bacteria (LAB) isolated from poultry gut, feces of rat, chicken, human infants, and fermented foods were characterized for desired probiotic functional properties including the phytase-producing ability which is one of the wanted characteristics for probiotics for potential applications for upgrading animal nutrition, enhancing feed conversion, and minimizing anti-nutritional properties. Among 62 LAB isolates Weissella kimchii R-3 an isolate from poultry gut exhibited substantial phytase-producing ability (1.77 U/ml) in addition to other functional probiotic characteristics viz. hydrophobicity, autoaggregation, coaggregation with bacterial pathogens, and antimicrobial activity against pathogens. Survival of W. kimchii R-3 cells (in free and calcium alginate encapsulated state) was examined sequentially in simulated gastric and intestinal juices. Encapsulated cells exhibited better survival under simulated gut conditions indicating that encapsulation conferred considerable protection against adverse gut conditions. Furthermore, simulated gastric and intestinal juices with pepsin and pancreatin showed higher survival of cells than the juices without pepsin and pancreatin. W. kimchii R-3 due to its significant functional probiotic attributes may have prospective for commercial applications in human/animal nutrition.

  1. The presence of biofilm-producing bacteria on tonsils is associated with increased exhaled nitric oxide levels: preliminary data in children who experience recurrent exacerbations of chronic tonsillitis.

    Science.gov (United States)

    Torretta, S; Marchisio, P; Drago, L; Capaccio, P; Baggi, E; Pignataro, L

    2015-03-01

    It has been suggested that bacterial biofilms may be a causative factor in the aetiopathogenesis of chronic tonsillitis. Involvement of exhaled nitric oxide has been previously considered, with conflicting findings. A pilot study was performed to investigate the relationship between exhaled nitric oxide levels and the presence of tonsillar biofilm-producing bacteria in children with chronic tonsillitis. Tonsillar biofilm-producing bacteria on bioptic specimens taken during tonsillectomy were assessed by means of spectrophotometry. Analysis was based on 24 children aged 5-10 years (median, 7.5 years). Biofilm-producing bacteria were found in 40.9 per cent of specimens. The median exhaled nitric oxide level was 11.6 ppb (range, 3.2-22.3 ppb). There was a significant relationship between the presence of biofilm-producing bacteria and increased exhaled nitric oxide levels (p = 0.03). Children with exhaled nitric oxide levels of more than 8 ppb were at three times greater risk of developing tonsillar biofilm-producing bacteria than those with lower levels. Our findings suggest the possibility of discriminating children with chronic biofilm-sustained tonsillar infections on the basis of exhaled nitric oxide levels.

  2. A review of high temperature co-electrolysis of H2O and CO2 to produce sustainable fuels using solid oxide electrolysis cells (SOECs): advanced materials and technology.

    Science.gov (United States)

    Zheng, Yun; Wang, Jianchen; Yu, Bo; Zhang, Wenqiang; Chen, Jing; Qiao, Jinli; Zhang, Jiujun

    2017-02-06

    High-temperature solid oxide electrolysis cells (SOECs) are advanced electrochemical energy storage and conversion devices with high conversion/energy efficiencies. They offer attractive high-temperature co-electrolysis routes that reduce extra CO2 emissions, enable large-scale energy storage/conversion and facilitate the integration of renewable energies into the electric grid. Exciting new research has focused on CO2 electrochemical activation/conversion through a co-electrolysis process based on the assumption that difficult C[double bond, length as m-dash]O double bonds can be activated effectively through this electrochemical method. Based on existing investigations, this paper puts forth a comprehensive overview of recent and past developments in co-electrolysis with SOECs for CO2 conversion and utilization. Here, we discuss in detail the approaches of CO2 conversion, the developmental history, the basic principles, the economic feasibility of CO2/H2O co-electrolysis, and the diverse range of fuel electrodes as well as oxygen electrode materials. SOEC performance measurements, characterization and simulations are classified and presented in this paper. SOEC cell and stack designs, fabrications and scale-ups are also summarized and described. In particular, insights into CO2 electrochemical conversions, solid oxide cell material behaviors and degradation mechanisms are highlighted to obtain a better understanding of the high temperature electrolysis process in SOECs. Proposed research directions are also outlined to provide guidelines for future research.

  3. Prevalence and molecular characterization of carbapenemase-producing gram-negative bacteria from a university hospital in China.

    Science.gov (United States)

    Sun, Yao; Li, Meimei; Chen, Lijiang; Chen, Huale; Yu, Xiao; Ye, Jianzhong; Zhang, Yapei; Ma, Chuanling; Zhou, Tieli

    2016-02-01

    The increasing emergence of carbapenem resistance in gram-negative bacteria associated with carbapenemase prompted the initiation of this study. A total of 3139 gram-negative bacteria were recovered from a 3380-bed university hospital in Wenzhou during 2008 and 2012. Antimicrobial susceptibility was determined using the VITEK2 Compact System and agar dilution method. The phenotype and genotype of carbapenemase were demonstrated using the modified Hodge test, PCR and sequencing. A conjugation experiment was performed to reveal the transferability of resistant genes. The location of the carbapenemase gene was studied by plasmid analysis and southern blot hybridization. Clonal relatedness of the isolates was investigated by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Overall, 751 of 3139 isolates (71/2055 Enterobacteriaceae, 510/620 Acinetobacter baumannii and 170/464 Pseudomonas aeruginosa) exhibited resistance to carbapenem. Carbapenemase-encoding genes were detected in 70.4% (50/71) of carbapenem-resistant Enterobacteriaceae, including blaKPC (80%) and blaIMP (20%). All A. baumannii subjected to genotype analysis were positive for blaOXA-51-like and co-harboured blaOXA-23-like (80.4%) and blaIMP (7.8%). ISAba1 was found upstream of blaOXA-23-like and blaOXA-51-like. Eight and seven strains of 170 P. aeruginosa carried blaIMP and blaVIM, respectively. PFGE analysis identified at least one dominant genotype in certain species. Four KPC-2-producing Klebsiella pneumoniae belonged to the same sequence type ST11. The plasmids carrying blaKPC were successfully transferred into recipient strains. This study highlights the challenge of increasing prevalence of carbapenem resistance associated with carbapenemase genes and dissemination of epidemic clones in Wenzhou, China.

  4. Evaluation of Different Phenotypic Techniques for the Detection of Slime Produced by Bacteria Isolated from Clinical Specimens

    Science.gov (United States)

    HRV, Rajkumar; Devaki, Ramakrishna

    2016-01-01

    Introduction  Microorganisms use various strategies for their survival in both the environment and in humans. Slime production by bacteria is one such mechanism by which microbes colonize on the indwelling prosthetic devices and form biofilms. Infections caused by such microorganisms are difficult to treat as the biofilm acts as a shield and protects microbes against antimicrobial agents. There are several methods for the detection of slime produced by bacteria, and they include both phenotypic and molecular methods. The present study evaluated the Congo red agar/broth method, Christensen’s method, dye elution technique, and the latex agglutination method for the demonstration of slime production by different bacterial clinical isolates. Materials & Methods We collected 151 bacterial clinical isolates (both gram-positive and gram-negative bacteria) from various specimens and tested them for the production of slime both by qualitative and quantitative tests. Congo red agar/broth method, Christensen's method, dye elution technique, and latex agglutination methods were used for detecting the slime or slime-like substance. Results  We found that 103 (68.2%) strains were positive for slime production by Congo red agar/broth method. It was found that 18 (94.7%) strains of Klebsiella pneumoniae, 21 (84.0%) strains of S aureus and 25 (65.7%) strains of coagulase-negative Staphylococci were positive for slime or slime-like substances by Congo red agar/broth method. A total of 41.0% of the strains positive by Christensen's method and 15.2% of the strains by dye elution technique were found to be more adherent organisms and that have the potential to form biofilms. Only the gram-positive organisms showed nonspecific agglutination with latex suspension. Conclusion  Among the various phenotypic methods compared in this study the Congo red agar/broth method is a simple, economical, sensitive, and specific method that can be used by clinical microbiology laboratories

  5. Isolation and Characterization of a New High Efficient H2-producing Bacterium Enterococcus sp.LG1%高效产氢菌株Enterococcus sp.LG1的分离及产氢特性

    Institute of Scientific and Technical Information of China (English)

    李宇亮; 李小明; 郭亮; 周屹; 曾光明; 杨麒; 廖德祥

    2008-01-01

    采用Hungate厌氧培养技术分别从厌氧污泥、好氧污泥及河底泥中分离出12株厌氧产氢细菌,并对其中的Enterococcus sp.LG1(注册号:EU258743)进行了研究.结果表明,该株细菌为专性厌氧菌,经革兰氏染色结果为阴性.通过16S rDNA碱基测序和比对证实,该菌株是目前尚未报道过的1个新菌种,初步确定其细菌学上的分类地位.同时,以灭菌预处理的污泥为底物培养基,对该菌的产氢能力及污泥发酵过程中底物性质变化(SCOD、可溶性蛋白质、总糖和pH值等)进行了探讨.实验结果显示,产氢茵Enterococcus sp.LG1的发酵过程中只有H2和CO2产生,无CH4产生.产气量最高为36.48 mL/g TCOD,氢气含量高达73.5%,为已报道文献中以污泥为底物发酵制氢中之最高.根据污泥发酵产物分析得知,该菌的发酵类行为典型的丁酸型发酵.

  6. Presence of Acylated Homoserine Lactones (AHLs) and AHL-Producing Bacteria in Meat and Potential Role of AHL in Spoilage of Meat

    OpenAIRE

    Bruhn, Jesper Bartholin; Christensen, Allan Beck; Flodgaard, Lars Ravn; Nielsen, Kristian Fog; Larsen, Thomas Ostenfeld; Givskov, Michael; Gram, Lone

    2004-01-01

    Quorum-sensing (QS) signals (N-acyl homoserine lactones [AHLs]) were extracted and detected from five commercially produced vacuum-packed meat samples. Ninety-six AHL-producing bacteria were isolated, and 92 were identified as Enterobacteriaceae. Hafnia alvei was the most commonly identified AHL-producing bacterium. Thin-layer chromatographic profiles of supernatants from six H. alvei isolates and of extracts from spoiling meat revealed that the major AHL species had an Rf value and shape sim...

  7. Bifidobacteria and Butyrate-Producing Colon Bacteria: Importance and Strategies for Their Stimulation in the Human Gut.

    Science.gov (United States)

    Rivière, Audrey; Selak, Marija; Lantin, David; Leroy, Frédéric; De Vuyst, Luc

    2016-01-01

    With the increasing amount of evidence linking certain disorders of the human body to a disturbed gut microbiota, there is a growing interest for compounds that positively influence its composition and activity through diet. Besides the consumption of probiotics to stimulate favorable bacterial communities in the human gastrointestinal tract, prebiotics such as inulin-type fructans (ITF) and arabinoxylan-oligosaccharides (AXOS) can be consumed to increase the number of bifidobacteria in the colon. Several functions have been attributed to bifidobacteria, encompassing degradation of non-digestible carbohydrates, protection against pathogens, production of vitamin B, antioxidants, and conjugated linoleic acids, and stimulation of the immune system. During life, the numbers of bifidobacteria decrease from up to 90% of the total colon microbiota in vaginally delivered breast-fed infants to <5% in the colon of adults and they decrease even more in that of elderly as well as in patients with certain disorders such as antibiotic-associated diarrhea, inflammatory bowel disease, irritable bowel syndrome, obesity, allergies, and regressive autism. It has been suggested that the bifidogenic effects of ITF and AXOS are the result of strain-specific yet complementary carbohydrate degradation mechanisms within cooperating bifidobacterial consortia. Except for a bifidogenic effect, ITF and AXOS also have shown to cause a butyrogenic effect in the human colon, i.e., an enhancement of colon butyrate production. Butyrate is an essential metabolite in the human colon, as it is the preferred energy source for the colon epithelial cells, contributes to the maintenance of the gut barrier functions, and has immunomodulatory and anti-inflammatory properties. It has been shown that the butyrogenic effects of ITF and AXOS are the result of cross-feeding interactions between bifidobacteria and butyrate-producing colon bacteria, such as Faecalibacterium prausnitzii (clostridial cluster IV

  8. Hydrogen polysulfide (H2S n ) signaling along with hydrogen sulfide (H2S) and nitric oxide (NO).

    Science.gov (United States)

    Kimura, Hideo

    2016-11-01

    Hydrogen sulfide (H2S) is a physiological mediator with various roles, including neuro-modulation, vascular tone regulation, and cytoprotection against ischemia-reperfusion injury, angiogenesis, and oxygen sensing. Hydrogen polysulfide (H2S n ), which possesses a higher number of sulfur atoms than H2S, recently emerged as a potential signaling molecule that regulates the activity of ion channels, a tumor suppressor, transcription factors, and protein kinases. Some of the previously reported effects of H2S are now attributed to the more potent H2S n . H2S n is produced by 3-mercaptopyruvate sulfurtransferase (3MST) from 3-mercaptopyruvate (3MP) and is generated by the chemical interaction of H2S with nitric oxide (NO). H2S n sulfhydrates (sulfurates) cysteine residues of target proteins and modifies their activity, whereas H2S sulfurates oxidized cysteine residues as well as reduces cysteine disulfide bonds. This review focuses on the recent progress made in studies concerning the production and physiological roles of H2S n and H2S.

  9. H2 cycling and microbial bioenergetics in anoxic sediments

    Science.gov (United States)

    Hoehler, Tori M.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    The simple biochemistry of H2 is central to a large number of microbial processes, affecting the interaction of organisms with each other and with the environment. In anoxic sediments, the great majority of microbial redox processes involve H2 as a reactant, product, or potential by-product, and the thermodynamics of these processes are thus highly sensitive to fluctuations in environmental H2 concentrations. In turn, H2 concentrations are controlled by the activity of H2-consuming microorganisms, which efficiently utilize this substrate down to levels which correspond to their bioenergetic limitations. Consequently, any environmental change which impacts the thermodynamics of H2-consuming organisms is mirrored by a corresponding change in H2 concentrations. This phenomenon is illustrated in anoxic sediments from Cape Lookout Bight, NC, USA: H2 concentrations are controlled by a suite of environmental parameters (e.g., temperature, sulfate concentrations) in a fashion which can be quantitatively described by a simple thermodynamic model. These findings allow us to calculate the apparent minimum quantity of biologically useful energy in situ. We find that sulfate reducing bacteria are not active at energy yields below -18 kJ per mole sulfate, while methanogenic archaea exhibit a minimum close to -10 kJ per mole methane.

  10. Chemolithotrophic acetogenic H2/CO2 utilization in Italian rice field soil.

    Science.gov (United States)

    Liu, Fanghua; Conrad, Ralf

    2011-09-01

    Acetate oxidation in Italian rice field at 50 °C is achieved by uncultured syntrophic acetate oxidizers. As these bacteria are closely related to acetogens, they may potentially also be able to synthesize acetate chemolithoautotrophically. Labeling studies using exogenous H(2) (80%) and (13)CO(2) (20%), indeed demonstrated production of acetate as almost exclusive primary product not only at 50 °C but also at 15 °C. Small amounts of formate, propionate and butyrate were also produced from (13)CO(2). At 50 °C, acetate was first produced but later on consumed with formation of CH(4). Acetate was also produced in the absence of exogenous H(2) albeit to lower concentrations. The acetogenic bacteria and methanogenic archaea were targeted by stable isotope probing of ribosomal RNA (rRNA). Using quantitative PCR, (13)C-labeled bacterial rRNA was detected after 20 days of incubation with (13)CO(2). In the heavy fractions at 15 °C, terminal restriction fragment length polymorphism, cloning and sequencing of 16S rRNA showed that Clostridium cluster I and uncultured Peptococcaceae assimilated (13)CO(2) in the presence and absence of exogenous H(2), respectively. A similar experiment showed that Thermoanaerobacteriaceae and Acidobacteriaceae were dominant in the (13)C treatment at 50 °C. Assimilation of (13)CO(2) into archaeal rRNA was detected at 15 °C and 50 °C, mostly into Methanocellales, Methanobacteriales and rice cluster III. Acetoclastic methanogenic archaea were not detected. The above results showed the potential for acetogenesis in the presence and absence of exogenous H(2) at both 15 °C and 50 °C. However, syntrophic acetate oxidizers seemed to be only active at 50 °C, while other bacterial groups were active at 15 °C.

  11. pH dependence of proton translocation in the oxidative and reductive phases of the catalytic cycle of cytochrome c oxidase. The role of H2O produced at the oxygen-reduction site.

    Science.gov (United States)

    Capitanio, Giuseppe; Martino, Pietro Luca; Capitanio, Nazzareno; De Nitto, Emanuele; Papa, Sergio

    2006-02-14

    A study is presented on the pH dependence of proton translocation in the oxidative and reductive phases of the catalytic cycle of purified cytochrome c oxidase (COX) from beef heart reconstituted in phospholipid vesicles (COV). Protons were shown to be released from COV both in the oxidative and reductive phases. In the oxidation by O2 of the fully reduced oxidase, the H+/COX ratio for proton release from COV (R --> O transition) decreased from approximately 2.4 at pH 6.5 to approximately 1.8 at pH 8.5. In the direct reduction of the fully oxidized enzyme (O --> R transition), the H+/COX ratio for proton release from COV increased from approximately 0.3 at pH 6.5 to approximately 1.6 at pH 8.5. Anaerobic oxidation by ferricyanide of the fully reduced oxidase, reconstituted in COV or in the soluble case, resulted in H+ release which exhibited, in both cases, an H+/COX ratio of 1.7-1.9 in the pH range 6.5-8.5. This H+ release associated with ferricyanide oxidation of the oxidase, in the absence of oxygen, originates evidently from deprotonation of acidic groups in the enzyme cooperatively linked to the redox state of the metal centers (redox Bohr protons). The additional H+ release (O2 versus ferricyanide oxidation) approaching 1 H+/COX at pH or = 8.5, this additional proton release takes place in the reductive phase of the catalytic cycle of the oxidase. The H+/COX ratio for proton release from COV in the overall catalytic cycle, oxidation by O2 of the fully reduced oxidase directly followed by re-reduction (R --> O --> R transition), exhibited a bell-shaped pH dependence approaching 4 at pH 7.2. A mechanism for the involvement in the proton pump of the oxidase of H+/e- cooperative coupling at the metal centers (redox Bohr effects) and protonmotive steps of reduction of O2 to H2O is presented.

  12. Kinetic Energy Distribution of H(2p) Atoms from Dissociative Excitation of H2

    Science.gov (United States)

    Ajello, Joseph M.; Ahmed, Syed M.; Kanik, Isik; Multari, Rosalie

    1995-01-01

    The kinetic energy distribution of H(2p) atoms resulting from electron impact dissociation of H2 has been measured for the first time with uv spectroscopy. A high resolution uv spectrometer was used for the measurement of the H Lyman-alpha emission line profiles at 20 and 100 eV electron impact energies. Analysis of the deconvolved 100 eV line profile reveals the existence of a narrow line peak and a broad pedestal base. Slow H(2p) atoms with peak energy near 80 meV produce the peak profile, which is nearly independent of impact energy. The wings of H Lyman-alpha arise from dissociative excitation of a series of doubly excited Q(sub 1) and Q(sub 2) states, which define the core orbitals. The fast atom energy distribution peaks at 4 eV.

  13. How do marine bacteria produce light, why are they luminescent, and can we employ bacterial bioluminescence in aquatic biotechnology?

    OpenAIRE

    Grzegorz Wêgrzyn; Agata Czy¿

    2002-01-01

    Bioluminescence, the phenomenon of light production by living organisms, occurs in forms of life as various as bacteria, fungi and animals. Nevertheless, light-emitting bacteria are the most abundant and widespread of luminescent organisms. Interestingly, most species of such bacteria live in marine environments. In this article, the biochemical mechanism of bacterial luminescence and its genetic regulation are summarized. Although the biochemistry and genetics of light emission by cel...

  14. Colistin and tigecycline resistance in carbapenemase-producing Gram-negative bacteria: emerging resistance mechanisms and detection methods.

    Science.gov (United States)

    Osei Sekyere, J; Govinden, U; Bester, L A; Essack, S Y

    2016-09-01

    A literature review was undertaken to ascertain the molecular basis for tigecycline and colistin resistance mechanisms and the experimental basis for the detection and delineation of this resistance particularly in carbapenemase-producing Gram-negative bacteria. Pubmed, Google Scholar and Science Direct were searched with the keywords colistin, tigecycline, resistance mechanisms and detection methods. Trans-complementation and comparative MIC studies, mass spectrometry, chromatography, spectrofluorometry, PCR, qRT-PCR and whole genome sequencing (WGS) were commonly used to determine tigecycline and colistin resistance mechanisms, specifically modifications in the structural and regulatory efflux (acrAB, OqxAB, kpgABC adeABC-FGH-IJK, mexAB-XY-oprJM and soxS, rarA robA, ramRAB marRABC, adeLRS, mexRZ and nfxb) and lipid A (pmrHFIJFKLM, lpxA, lpxC lpxD and mgrB, pmrAB, phoPQ,) genes respectively. Mutations in the ribosomal 16S rRNA operon rrnBC, also yielded resistance to tigecycline through target site modifications. The mcr-1 gene conferring resistance to colistin was identified via WGS, trans-complementation and a murine thigh infection model studies. Common detection methods are mainly antibiotic sensitivity testing with broth microdilution while molecular identification tools are mostly PCR and WGS. Spectrofluorometry, MALDI-TOF MS, micro-array and real-time multiplex PCR hold much promise for the future as new detection tools.

  15. Identification of acetic acid bacteria in traditionally produced vinegar and mother of vinegar by using different molecular techniques.

    Science.gov (United States)

    Yetiman, Ahmet E; Kesmen, Zülal

    2015-07-02

    Culture-dependent and culture-independent methods were combined for the investigation of acetic acid bacteria (AAB) populations in traditionally produced vinegars and mother of vinegar samples obtained from apple and grape. The culture-independent denaturing gradient gel electrophoresis (DGGE) analysis, which targeted the V7-V8 regions of the 16S rRNA gene, showed that Komagataeibacter hansenii and Komagataeibacter europaeus/Komagataeibacter xylinus were the most dominant species in almost all of the samples analyzed directly. The culture-independent GTG5-rep PCR fingerprinting was used in the preliminary characterization of AAB isolates and species-level identification was carried out by sequencing of the 16S rRNA gene, 16S-23S rDNA internally transcribed to the spacer (ITS) region and tuf gene. Acetobacter okinawensis was frequently isolated from samples obtained from apple while K. europaeus was identified as the dominant species, followed by Acetobacter indonesiensis in the samples originating from grape. In addition to common molecular techniques, real-time PCR intercalating dye assays, including DNA melting temperature (Tm) and high resolution melting analysis (HRM), were applied to acetic acid bacterial isolates for the first time. The target sequence of ITS region generated species-specific HRM profiles and Tm values allowed discrimination at species level.

  16. Occurrence of bacteria producing broad-spectrum beta-lactamases and qnr genes in hospital and urban wastewater samples.

    Science.gov (United States)

    Röderová, Magdaléna; Sedláková, Miroslava Htoutou; Pudová, Vendula; Hricová, Kristýna; Silová, Romana; Imwensi, Peter Eghonghon Odion; Bardoň, Jan; Kolář, Milan

    2016-04-01

    The aims were to investigate the level of antibiotic-resistant bacteria in hospital and urban wastewater and to determine the similarity of isolates obtained from wastewater and hospitalized patients. Wastewater samples were collected in September 2013 and 2014. After identification using MALDI-TOF MS, beta-lactamase production was determined by relevant phenotypic tests. Genes responsible for the production of single beta-lactamase groups and Qnr proteins were established. The epidemiological relationship of the isolates from wastewater and hospitalized patients was determined by PFGE. A total of 51 isolates of enterobacteria were obtained. Overall, 45.1% of them produced broad-spectrum beta-lactamases. Genes encoding TEM, SHV, CTX-M, CIT, DHA and EBC types of enzymes and Qnr proteins were detected. No broad-spectrum beta-lactamase production was confirmed in the urban wastewater treatment plant. The most important finding was the detection of two identical isolates of K. pneumoniae in 2013, one from a patient's urinary catheter and the other from a wastewater sample.

  17. Reducing sugar-producing bacteria from guts of Tenebrio molitor Linnaeus (yellow mealworm) for lignocellulosic waste minimization.

    Science.gov (United States)

    Qi, Wei; Chen, Chia-Lung; Wang, Jing-Yuan

    2011-01-01

    The guts of Tenebrio Molitor Linnaeus (yellow mealworm) were used as inocula to isolate reducing sugar-producing bacteria during bioconversion of lignocellulose to reducing sugars in this study. Three carbon sources, i.e., carboxymethyl cellulose (CMC), filter paper (FP), and lignocellulosic waste (LIG), were specifically selected; and two types of culturing media (M1 and M2) were used. After 6 months of sequential cultivation, lignocellulose (i.e., polysaccharides) degradation of enrichments M1-CMC (47.5%), M1-FP (73.3%), M1-LIG (70.4%), M2-CMC (55.7%), M2-FP (73.1%) and M2-LIG (71.7%) was achieved, respectively, with incubation for 48 h. Furthermore, seven bacterial strains were successfully isolated corresponding to most of the major bands detected by denaturing gradient gel electrophoresis analysis. The maximum reducing sugars yield by the combination of Agromyces sp. C42 and Stenotrophomonas sp. A10b was 56.7 mg g·LIG(-1) of 48 h, which is approximate 2-5 times higher than the original enrichments and individual microbial strains. These findings suggest that bioconversion by microorganisms from mealworm guts has great application potential for lignocellulose hydrolysis.

  18. Extended-spectrum beta-lactamase-producing bacteria isolated from hematologic patients in Manaus, State of Amazonas, Brazil

    Directory of Open Access Journals (Sweden)

    Cristina Motta Ferreira

    2011-09-01

    Full Text Available Antibiotic therapy in hematologic patients, often weak and susceptible to a wide range of infections, particularly nosocomial infections derived from long hospitalization periods, is a challenging issue. This paper presents ESBL-producing strains isolated from such hematologic patients treated at the Amazon Hematology and Hemotherapy Foundation (HEMOAM in the Brazilian Amazon Region to identify the ESBL genes carried by them as well as the susceptibility to 11 antimicrobial agents using the E-test method. A total of 146 clinical samples were obtained from July 2007 to August 2008, when 17 gram-negative strains were isolated in our institution. The most frequent isolates confirmed by biochemical tests and 16S rRNA sequencing were E. coli (8/17, Serratia spp. (3/17 and B.cepacia (2/17. All gram-negative strains were tested for extended-spectrum-beta-lactamases (ESBLs, where: (12/17 strains carried ESBL; among these, (8/12 isolates carried blaTEM, blaCTX-M, blaOXA, blaSHV genes, (1/12 blaTEM gene and (3/12 blaTEM, blaCTX-M, blaOXA genes. Antibiotic resistance was found in (15/17 of the isolates for tetracycline, (12/17 for ciprofloxacin, (1/17 resistance for cefoxitin and chloramphenicol, (1/17 for amikacin and (3/17 cefepime. This research showed the presence of gram-negative ESBL-producing bacteria infecting hematologic patients in HEMOAM. These strains carried the blaTEM, blaSHV, blaCTX-M and blaOXA genes and were resistant to different antibiotics used in the treatment. This finding was based on a period of 13 months, during which clinical samples from specific populations were obtained. Therefore, caution is required when generalizing the results that must be based on posological orientations and new breakpoints for disk diffusion and microdilution published by CLSI 2010.

  19. Potentiation of the cytotoxic activity of copper by polyphosphate on biofilm-producing bacteria: a bioinspired approach.

    Science.gov (United States)

    Müller, Werner E G; Wang, Xiaohong; Guo, Yue-Wei; Schröder, Heinz C

    2012-10-25

    Adhesion and accumulation of organic molecules represent an ecologically and economically massive problem. Adhesion of organic molecules is followed by microorganisms, unicellular organisms and plants together with their secreted soluble and structure-associated byproducts, which damage unprotected surfaces of submerged marine structures, including ship hulls and heat exchangers of power plants. This is termed biofouling. The search for less toxic anti-biofilm strategies has intensified since the ban of efficient and cost-effective anti-fouling paints, enriched with the organotin compound tributyltin, not least because of our finding of the ubiquitous toxic/pro-apoptotic effects displayed by this compound. Our proposed bio-inspired approach for controlling, suppressing and interfluencing the dynamic biofouling complex uses copper as one component in an alternative anti-fouling system. In order to avoid and overcome the potential resistance against copper acquired by microorganisms we are using the biopolymer polyphosphate (polyP) as a further component. Prior to being functionally active, polyP has to be hydrolyzed to ortho-phosphate which in turn can bind to copper and export the toxic compound out of the cell. It is shown here that inhibition of the hydrolysis of polyP by the bisphosphonate DMDP strongly increases the toxic effect of copper towards the biofilm-producing Streptococcus mutans in a synergistic manner. This bisphosphonate not only increases the copper-caused inhibition of cell growth but also of biofilm production by the bacteria. The defensin-related ASABF, a marine toxin produced by the sponge Suberites domuncula, caused only an additive inhibitory effect in combination with copper. We conclude that the new strategy, described here, has a superior anti-biofilm potential and can be considered as a novel principle for developing bio-inspired antifouling compounds, or cocktails of different compounds, in the future.

  20. Potentiation of the Cytotoxic Activity of Copper by Polyphosphate on Biofilm-Producing Bacteria: A Bioinspired Approach

    Directory of Open Access Journals (Sweden)

    Heinz C. Schröder

    2012-10-01

    Full Text Available Adhesion and accumulation of organic molecules represent an ecologically and economically massive problem. Adhesion of organic molecules is followed by microorganisms, unicellular organisms and plants together with their secreted soluble and structure-associated byproducts, which damage unprotected surfaces of submerged marine structures, including ship hulls and heat exchangers of power plants. This is termed biofouling. The search for less toxic anti-biofilm strategies has intensified since the ban of efficient and cost-effective anti-fouling paints, enriched with the organotin compound tributyltin, not least because of our finding of the ubiquitous toxic/pro-apoptotic effects displayed by this compound [1]. Our proposed bio-inspired approach for controlling, suppressing and interfluencing the dynamic biofouling complex uses copper as one component in an alternative anti-fouling system. In order to avoid and overcome the potential resistance against copper acquired by microorganisms we are using the biopolymer polyphosphate (polyP as a further component. Prior to being functionally active, polyP has to be hydrolyzed to ortho-phosphate which in turn can bind to copper and export the toxic compound out of the cell. It is shown here that inhibition of the hydrolysis of polyP by the bisphosphonate DMDP strongly increases the toxic effect of copper towards the biofilm-producing Streptococcus mutans in a synergistic manner. This bisphosphonate not only increases the copper-caused inhibition of cell growth but also of biofilm production by the bacteria. The defensin-related ASABF, a marine toxin produced by the sponge Suberites domuncula, caused only an additive inhibitory effect in combination with copper. We conclude that the new strategy, described here, has a superior anti-biofilm potential and can be considered as a novel principle for developing bio-inspired antifouling compounds, or cocktails of different compounds, in the future.

  1. On Robust H2 Estimation

    Institute of Scientific and Technical Information of China (English)

    Lihua Xie

    2005-01-01

    The problem of state estimation for uncertain systems has attracted a recurring interest in the past decade. In this paper, we shall give an overview on some of the recent development in the area by focusing on the robust H2 (Kaiman) filtering of uncertain discrete-time systems. The robust H2 estimation is concerned with the design of a fixed estimator for a family of plants under consideration such that the estimation error covariance is of a minimal upper bound. The uncertainty under consideration includes norm-bounded uncertainty and polytopic uncertainty. In the finite horizon case, we shall discuss a parameterized difference Riccati equation approach for systems with normbounded uncertainty and pinpoint the difference of state estimation between systems without uncertainty and those with uncertainty. In the infinite horizon case, we shall deal with both the norm-bounded and polytopic uncertainties using a linear matrix inequality (LMI) approach. In particular, we shall demonstrate how the conservatism of design can be improved using a slack variable technique. We also propose an iterative algorithm to refine a designed estimator. An example will be given to compare estimators designed using various techniques.

  2. Comparison of two rapid biochemical tests and four chromogenic selective media for detection of carbapenemase-producing Gram-negative bacteria.

    Science.gov (United States)

    Hinić, Vladimira; Amrein, Ivo; Stammler, Sabrina; Heckendorn, Judith; Meinel, Dominik; Frei, Reno; Egli, Adrian

    2017-04-01

    We evaluated RAPIDEC® CARBA NP, Neo-Rapid CARB, chromID® CARBA SMART (CARB/OXA), Brilliance™ CRE/ESBL, ChromArt CRE and BBL™ CHROMagar™ CPE for the detection of carbapenemase-producing bacteria. The analytical sensitivity of RAPIDEC® CARBA NP was better than that of Neo-Rapid CARB. A combination of carbapenemase and ESBL screening plates could be advantageous.

  3. Community-acquired febrile urinary tract infection caused by extended-spectrum beta-lactamase-producing bacteria in hospitalised infants.

    Science.gov (United States)

    Hernández Marco, Roberto; Guillén Olmos, Elena; Bretón-Martínez, José Rafael; Giner Pérez, Lourdes; Casado Sánchez, Benedicta; Fujkova, Julia; Salamanca Campos, Marina; Nogueira Coito, José Miguel

    2017-05-01

    Extended-spectrum beta-lactamase (ESBL) producing bacteria are infrequent pathogens of urinary tract infections in children. The objective of our study was to investigate the presence, clinically associated characteristics and risk factors for acquisition of urinary tract infection/acute pyelonephritis (UTI/APN) in hospitalised children <2years old caused by community-acquired ESBL. A case-control study in a second level community hospital in Spain, in which 537 episodes of UTI/APN were investigated in a retrospective study between November 2005 and August 2014. Cases were patients with ESBL strains. For each case, four ESBL-negative controls were selected. A questionnaire with the variables of interest was completed for every patient, and the groups were compared. ESBL-positive strains were found in 19 (3,5%) cultures. Of these 16 (84%) were Escherichia coli. Vesicoureteral reflux (VUR) of any grade was more frequent in the ESBL group (60 vs. 29%), although without statistical significance. Relapses were more frequent in the ESBL group (42% vs. 18%) (P=.029; OR=3.2; 95%CI: 1.09-9.5). The prevalence of UTI/APN due to ESBL-positive strains increased slightly from 2.7% in the period 2005-2009 to 4.4% in the period 2010-2014. ESBL UTI/APN were associated with more frequent relapses. VUR of any grade was twice more frequent in the ESBL group. Piperacillin/tazobactam, fosfomycin and meropenem showed an excellent activity. Aminoglycosides may be a therapeutic option, and in our patients gentamicin was the antibiotic most used. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  4. Ureases display biological effects independent of enzymatic activity: Is there a connection to diseases caused by urease-producing bacteria?

    Directory of Open Access Journals (Sweden)

    D. Olivera-Severo

    2006-07-01

    Full Text Available Ureases are enzymes from plants, fungi and bacteria that catalyze the hydrolysis of urea to form ammonia and carbon dioxide. While fungal and plant ureases are homo-oligomers of 90-kDa subunits, bacterial ureases are multimers of two or three subunit complexes. We showed that some isoforms of jack bean urease, canatoxin and the classical urease, bind to glycoconjugates and induce platelet aggregation. Canatoxin also promotes release of histamine from mast cells, insulin from pancreatic cells and neurotransmitters from brain synaptosomes. In vivo it induces rat paw edema and neutrophil chemotaxis. These effects are independent of ureolytic activity and require activation of eicosanoid metabolism and calcium channels. Helicobacter pylori, a Gram-negative bacterium that colonizes the human stomach mucosa, causes gastric ulcers and cancer by a mechanism that is not understood. H. pylori produces factors that damage gastric epithelial cells, such as the vacuolating cytotoxin VacA, the cytotoxin-associated protein CagA, and a urease (up to 10% of bacterial protein that neutralizes the acidic medium permitting its survival in the stomach. H. pylori whole cells or extracts of its water-soluble proteins promote inflammation, activate neutrophils and induce the release of cytokines. In this paper we review data from the literature suggesting that H. pylori urease displays many of the biological activities observed for jack bean ureases and show that bacterial ureases have a secretagogue effect modulated by eicosanoid metabolites through lipoxygenase pathways. These findings could be relevant to the elucidation of the role of urease in the pathogenesis of the gastrointestinal disease caused by H. pylori.

  5. Screening of Alginate Lyase-Producing Bacteria and Optimization of Media Compositions for Extracellular Alginate Lyase Production.

    Science.gov (United States)

    Tavafi, Hadis; Abdi-Ali, Ahya; Ghadam, Parinaz; Gharavi, Sara

    2017-01-01

    Alginate is a linear polysaccharide consisting of guluronate (polyG) and mannuronate (polyM) subunits. In the initial screening of alginate-degrading bacteria from soil, 10 isolates were able to grow on minimal medium containing alginate. The optimization of cell growth and alginate lyase (algL) production was carried out by the addition of 0.8% alginate and 0.2-0.3 M NaCl to the culture medium. Of 10 isolates, one was selected based on its fast growth rate on minimal 9 medium containing 0.4% sodium alginate. The selected bacterium, identified based on morphological and biochemical characteristics as well as 16S rDNA sequence data, was confirmed to be an isolate belonging to the genus Bacillus and designated as Bacillus sp. TAG8. Resuls: The results showed the ability of Bacillus sp. TAG8 to utilize alginate as a sole carbon source. Bacillus sp. TAG8 growth and algL production were augmented with an increase in sodium alginate concentration and also by the addition of 0.2-0.3 M NaCl. Molecular analysis of TAG8 algL gene showed 99% sequence identity with algL of Pseudomonas aeruginosa PAO1. algL produced by Bacillus sp. TAG8 cleaved both polyM and polyG blocks in alginate molecule as well as acetylated alginate residues, confirming the bifunctionality of the isolated lyase. The identification of novel algL genes from microbial communities constitutes a new approach for exploring lyases with specific activity against bacterial alginates and may thus contribute to the eradication of persistent biofilms from clinical samples.

  6. Ureases display biological effects independent of enzymatic activity: is there a connection to diseases caused by urease-producing bacteria?

    Science.gov (United States)

    Olivera-Severo, D; Wassermann, G E; Carlini, C R

    2006-07-01

    Ureases are enzymes from plants, fungi and bacteria that catalyze the hydrolysis of urea to form ammonia and carbon dioxide. While fungal and plant ureases are homo-oligomers of 90-kDa subunits, bacterial ureases are multimers of two or three subunit complexes. We showed that some isoforms of jack bean urease, canatoxin and the classical urease, bind to glycoconjugates and induce platelet aggregation. Canatoxin also promotes release of histamine from mast cells, insulin from pancreatic cells and neurotransmitters from brain synaptosomes. In vivo it induces rat paw edema and neutrophil chemotaxis. These effects are independent of ureolytic activity and require activation of eicosanoid metabolism and calcium channels. Helicobacter pylori, a Gram-negative bacterium that colonizes the human stomach mucosa, causes gastric ulcers and cancer by a mechanism that is not understood. H. pylori produces factors that damage gastric epithelial cells, such as the vacuolating cytotoxin VacA, the cytotoxin-associated protein CagA, and a urease (up to 10% of bacterial protein) that neutralizes the acidic medium permitting its survival in the stomach. H. pylori whole cells or extracts of its water-soluble proteins promote inflammation, activate neutrophils and induce the release of cytokines. In this paper we review data from the literature suggesting that H. pylori urease displays many of the biological activities observed for jack bean ureases and show that bacterial ureases have a secretagogue effect modulated by eicosanoid metabolites through lipoxygenase pathways. These findings could be relevant to the elucidation of the role of urease in the pathogenesis of the gastrointestinal disease caused by H. pylori.

  7. Screening of Alginate Lyase-Producing Bacteria and Optimization of Media Compositions for Extracellular Alginate Lyase Production

    Science.gov (United States)

    Tavafi, Hadis; Abdi- Ali, Ahya A; Ghadam, Parinaz; Gharavi, Sara

    2017-01-01

    Background: Alginate is a linear polysaccharide consisting of guluronate (polyG) and mannuronate (polyM) subunits. Methods: In the initial screening of alginate-degrading bacteria from soil, 10 isolates were able to grow on minimal medium containing alginate. The optimization of cell growth and alginate lyase (algL) production was carried out by the addition of 0.8% alginate and 0.2-0.3 M NaCl to the culture medium. Of 10 isolates, one was selected based on its fast growth rate on minimal 9 medium containing 0.4% sodium alginate. The selected bacterium, identified based on morphological and biochemical characteristics, as well as 16S rDNA sequence data, was confirmed to be an isolate belonging to the genus Bacillus and designated as Bacillus sp. TAG8. Results: The results showed the ability of Bacillus sp. TAG8 in utilizing alginate as a sole carbon source. Bacillus sp. TAG8 growth and algL production were augmented with an increase in sodium alginate concentration and also by the addition of 0.2-0.3 M NaCl. Molecular analysis of TAG8 algL gene showed 99% sequence identity with algL of Pseudomonas aeruginosa PAO1. The algL produced by Bacillus sp. TAG8 cleaved both polyM and polyG blocks in alginate molecule, as well as acetylated alginate residues, confirming the bifunctionality of the isolated lyase. Conclusion: The identification of novel algL genes from microbial communities constitutes a new approach for exploring lyases with specific activity against bacterial alginates and may thus contribute to the eradication of persistent biofilms from clinical samples. PMID:27432784

  8. Recurrences in chronic tonsillitis substained by tonsillar biofilm-producing bacteria in children. Relationship with the grade of tonsillar hyperplasy.

    Science.gov (United States)

    Torretta, Sara; Drago, Lorenzo; Marchisio, Paola; Cappadona, Maurizio; Rinaldi, Vittorio; Nazzari, Erica; Pignataro, Lorenzo

    2013-02-01

    It has been suggested that bacterial biofilms are involved in chronic tonsillar disease, but there is a lack of strong evidence concerning their etiopathogenic role in childhood chronic tonsillar infections. The aim of this study was to assess the presence of biofilm-producing bacteria (BPB) in tonsillar bioptic specimens taken from children with recurrent exacerbations of chronic hyperplastic tonsillitis, and to evaluate the possible relationship between them and the patients' demographic and clinical characteristics. 22 children (68.2% males; median age 6.5 years, range 3-13) with recurrent exacerbations of chronic hyperplastic tonsillitis were included. The presence of tonsillar BPB was assessed by means of the spectrophotometric analysis of tonsillar bioptic specimens taken during tonsillectomy between episodes of tonsillar infection. BPB were found in 50.0% of the 44 tonsillar specimens, and Staphylococcus aureus was the most frequent pathogen (81.8%). There was a significant relationship (p=0.02) between the grade of tonsillar hyperplasy (GTH) and the presence of tonsillar BPB, with an increased relative risk (RR=4.27, standard error=2.57, pchildren with GTH scores of >2. The findings of this study: (1) confirm the presence of tonsillar BPB in children with recurrent exacerbations of chronic tonsillar infections; (2) suggest that GTH is an important indicator of the presence of tonsillar BPB; and (3) raise the question as to whether tonsillar biofilm is a causative factor or just a consequence of recurrent exacerbations of chronic hyperplastic tonsillitis. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  9. Effects of H2 and electrochemical reducing power on metabolite production by Clostridium acetobutylicum KCTC1037.

    Science.gov (United States)

    Jeon, Boyoung; Yi, Junyeong; Park, Doohyun

    2014-01-01

    A conventional fermenter (CF), a single-cathode fermenter (SCF), and a double-cathode fermenter (DCF) were employed to evaluate and compare the effects of H2 and electrochemical reducing power on metabolite production by Clostridium acetobutylicum KCTC1037. The source of the external reducing power for CF was H2, for the SCF was electrochemically reduced neutral red-modified graphite felt electrode (NR-GF), and for the DCF was electrochemically reduced combination of NR-GF and platinum plate electrodes (NR-GF/PtP). The metabolites produced from glucose or CO2 by strain KCTC1037 cultivated in the DCF were butyrate, ethanol, and butanol, but ethanol and butanol were not produced from glucose or CO2 by strain KCTC1037 cultivated in the CF and SCF. It is possible that electrochemically reduced NR-GF/PtP is a more effective source of internal and external reducing power than H2 or NR-GF for strain KCTC1037 to produce metabolites from glucose and CO2. This research might prove useful in developing fermentation technology to actualize direct bioalcohol production of fermentation bacteria from CO2.

  10. Methanol synthesis on potassium modified Cu(100) from CO + H2 and CO + CO2 +H2

    DEFF Research Database (Denmark)

    Maack, M.; Friis-Jensen, Henriette; Sckerl, Susanne Quist;

    2003-01-01

    Methanol cannot be produced from CO + H-2 on a clean copper surface, but a promotional effect of potassium on methanol synthesis from mixtures of CO + H-2 and CO = CO2 + H-2 at a total pressure of 1.5 bar on a Cu(100) surface is shown in this work. The experiments are performed in a UHV chamber...... connected with a high-pressure cell (HPC). The methanol produced is measured with a gas chromatograph and the surface is characterized with surface science techniques. The results show that potassium is a promoter for the methanol synthesis from CO + H-2, and that the influence of CO2 is negligible....... Investigation of the post-reaction surface with TPD indicates that potassium carbonate is present and plays an important role. The activation energy is determined as 42 +/- 3 kJ/mol for methanol synthesis on K/Cu(100) from CO + H-2....

  11. Dual purpose microalgae-bacteria-based systems that treat wastewater and produce biodiesel and chemical products within a biorefinery.

    Science.gov (United States)

    Olguín, Eugenia J

    2012-01-01

    Excess greenhouse gas emissions and the concomitant effect on global warming have become significant environmental, social and economic threats. In this context, the development of renewable, carbon-neutral and economically feasible biofuels is a driving force for innovation worldwide. A lot of effort has been put into developing biodiesel from microalgae. However, there are still a number of technological, market and policy barriers that are serious obstacles to the economic feasibility and competitiveness of such biofuels. Conversely, there are also a number of business opportunities if the production of such alternative biofuel becomes part of a larger integrated system following the Biorefinery strategy. In this case, other biofuels and chemical products of high added value are produced, contributing to an overall enhancement of the economic viability of the whole integrated system. Additionally, dual purpose microalgae-bacteria-based systems for treating wastewater and production of biofuels and chemical products significantly contribute to a substantial saving in the overall cost of microalgae biomass production. These types of systems could help to improve the competitiveness of biodiesel production from microalgae, according to some recent Life Cycle Analysis studies. Furthermore, they do not compete for fresh water resources for agricultural purposes and add value to treating the wastewater itself. This work reviews the most recent and relevant information about these types of dual purpose systems. Several aspects related to the treatment of municipal and animal wastewater with simultaneous recovery of microalgae with potential for biodiesel production are discussed. The use of pre-treated waste or anaerobic effluents from digested waste as nutrient additives for weak wastewater is reviewed. Isolation and screening of microalgae/cyanobacteria or their consortia from various wastewater streams, and studies related to population dynamics in mixed cultures

  12. Stimulation of butyrate production by gluconic acid in batch culture of pig cecal digesta and identification of butyrate-producing bacteria.

    Science.gov (United States)

    Tsukahara, Takamitsu; Koyama, Hironari; Okada, Masaaki; Ushida, Kazunari

    2002-08-01

    Gluconic acid reaches the large intestine to stimulate lactic acid bacteria. However, the fermentation pattern of gluconic acid has yet to be elucidated. Accordingly, we examined the fermentation properties induced by gluconic acid in the pig cecal digesta in vitro. We also tested sorbitol and glucose, substrates for which the fermentation rate and patterns are known. The gluconic acid-utilizing bacteria were further isolated from pig cecal digesta and identified to examine the effect of gluconic acid on hind gut fermentation. Gluconic acid was fermented more slowly than were the other two substrates. Gluconic acid stimulated butyrate production; the butyrate molar percentage reached 26%, which is considered a high butyrate production. The majority of gluconic acid fermenters were identified as lactic acid bacteria, such as Lactobacillus reuteri and L. mucosae, and acid-utilizing bacteria, such as Megasphaera elsdenii and Mitsuokella multiacida. The gluconic acid fermented by lactic acid bacteria, and the lactate and acetate that were produced were used to form butyrate by acid-utilizing bacteria, such as M. elsdenii. Gluconic acid may be useful as a prebiotic to stimulate butyrate production in the large intestine.

  13. Pediococcus parvulus gtf gene encoding the GTF glycosyltransferase and its application for specific PCR detection of beta-D-glucan-producing bacteria in foods and beverages.

    Science.gov (United States)

    Werning, Maria Laura; Ibarburu, Idoia; Dueñas, Maria Teresa; Irastorza, Ana; Navas, Jesús; López, Paloma

    2006-01-01

    Exopolysaccharide production by lactic acid bacteria is beneficial in the dairy and oat-based food industries and is used to improve the texture of the fermented products. However, beta-D-glucan-producing bacteria are considered spoilage microorganisms in alcoholic beverages because their secreted exopolysaccharides alter the viscosity of cider, wine, and beer, rendering them unpalatable. The plasmidic glycosyltransferase (gtf) gene of the Pediococcus parvulus 2.6 strain isolated from ropy cider has been cloned and sequenced, and its GTF product was functionally expressed in Streptococcus pneumoniae. The GTF protein, which has glycosyltransferase activity, belongs to the COG1215 membrane-bound glycosyltransferase family, and agglutination tests revealed that the enzyme enables S. pneumoniae to synthesize beta-D-glucan. PCR amplification and Southern blot hybridization showed that the gtf gene is also present at different genomic locations in the beta-D-glucan producers Lactobacillus diolivorans G77 and Oenococcus oeni I4 strains, also isolated from ropy cider. A PCR assay has been developed for the detection of exopolysaccharide-producing bacteria. Forward and reverse primers, included respectively in the coding sequences of the putative glycosyltransferase domain and the fifth trans-membrane segment of the GTF, were designed. Analysis of 76 ropy and nonropy lactic acid bacteria validated the method for specific detection of beta-D-glucan homopolysaccharide producer Pediococcus, Lactobacillus, and Oenococcus strains. The limit of the assay in cider was 3 X 10(2) CFU/ml. This molecular method can be useful for the detection of ropy bacteria in cider before spoilage occurs, as well as for isolation of new exopolysaccharide-producing strains of industrial interest.

  14. H2S and Blood Vessels: An Overview.

    Science.gov (United States)

    Yang, Guangdong; Wang, Rui

    2015-01-01

    The physiological and biomedical importance of hydrogen sulfide (H2S) has been fully recognized in the cardiovascular system as well as in the rest of the body. In blood vessels, cystathionine γ-lyase (CSE) is a major H2S-producing enzyme expressed in both smooth muscle and endothelium as well as periadventitial adipose tissues. Regulation of H2S production from CSE is controlled by a complex integration of transcriptional, posttranscriptional, and posttranslational mechanisms in blood vessels. In smooth muscle cells, H2S regulates cell apoptosis, phenotypic switch, relaxation and contraction, and calcification. In endothelial cells, H2S controls cell proliferation, cellular senescence, oxidative stress, inflammation, etc. H2S interacts with nitric oxide and acts as an endothelium-derived relaxing factor and an endothelium-derived hyperpolarizing factor. H2S generated from periadventitial adipose tissues acts as an adipocyte-derived relaxing factor and modulates the vascular tone. Extensive evidence has demonstrated the beneficial roles of the CSE/H2S system in various blood vessel diseases, such as hypertension, atherosclerosis, and aortic aneurysm. The important roles signaling in the cardiovascular system merit further intensive and extensive investigation. H2S-releasing agents and CSE activators will find their great applications in the prevention and treatment of blood vessel-related disorders.

  15. PCR of crtNM combined with analytical biochemistry : an efficient way to identify carotenoid producing lactic acid bacteria

    OpenAIRE

    Turpin, W.; Renaud, Cécile; Avallone, S.; Hammoumi, A.; Guyot, Jean-Pierre; Humblot, Christèle

    2016-01-01

    Lactic acid bacteria (LAB) synthesize a wide variety of biochemical compounds during food fermentation. Carotenoids provide important biological functions for bacteria, and their consumption by humans has many beneficial effects. In this study, the presence of several genes involved in the production of carotenoids was determined by BLAST analysis and PCR in a collection of 156 LAB isolated from traditional amylaceous African fermented foods. Only the crtE gene and the crtNM operon were prese...

  16. Characterization of ACC deaminase-producing endophytic bacteria isolated from copper-tolerant plants and their potential in promoting the growth and copper accumulation of Brassica napus.

    Science.gov (United States)

    Zhang, Yan-Feng; He, Lin-Yan; Chen, Zhao-Jin; Wang, Qing-Ya; Qian, Meng; Sheng, Xia-Fang

    2011-03-01

    One hundred Cu-resistant-endophytic bacteria were isolated from Cu-tolerant plants grown on Cu mine wasteland, of which, eight Cu-resistant and 1-aminocyclopropane-1-carboxylate (ACC) deaminase-producing endophytic bacteria were obtained based on the ACC deaminase activity of the bacteria and characterized with respect to metal resistance, production of ACC deaminase, indole-3-acetic acid (IAA) as well as siderophores and mineral phosphate solubilization. Ralstonia sp. J1-22-2, Pantoea agglomerans Jp3-3, and Pseudomonas thivervalensis Y1-3-9 with higher ACC deaminase activity (ranging from 213 to 370 μM α-ketobutyrate mg(-1)h(-1)) were evaluated for promoting plant growth and Cu uptake of rape grown in quartz sand containing 0, 2.5, and 5 mg kg(-1) of Cu in pot experiments. The eight bacteria were found to exhibit different multiple heavy metal resistance characteristics, to show different levels of ACC deaminase activity and to produce indole acetic acid. Seven bacteria produced siderophores and solubilized inorganic phosphate. Pot experiments showed that inoculation with the strains (J1-22-2, Jp3-3, and Y1-3-9) was found to increase the biomass of rape. Increases in above-ground tissue Cu contents of rape cultivated in 2.5 and 5 mg kg(-1) of Cu-contaminated substrates varied from 9% to 31% and from 3 to 4-fold respectively in inoculated-rape plants compared to the uninoculated control. The maximum Cu uptake of rape was observed after inoculation with P. agglomerans Jp3-3. The results show that metal-resistant and plant growth promoting endophytic bacteria play an important role in plant growth and Cu uptake which may provide a new endophytic bacterial-assisted phytoremediation of Cu-contaminated environment.

  17. Assessing the yield, microstructure, and texture properties of miniature Chihuahua-type cheese manufactured with a phospholipase A1 and exopolysaccharide-producing bacteria.

    Science.gov (United States)

    Trancoso-Reyes, N; Gutiérrez-Méndez, N; Sepulveda, D R; Hernández-Ochoa, L R

    2014-02-01

    Chihuahua cheese or Mennonite cheese is one of the most popular and consumed cheeses in Mexico and by the Hispanic community in the United States. According to local producers the yield of Chihuahua cheese ranges from 9 to 9.5 kg of cheese from 100 kg of milk. Cheese yield is a crucial determinant of profitability in cheese-manufacturing plants; therefore, different methods have been developed to increase it. In this work, a miniature Chihuahua-type cheese model was used to assess the effect of a phospholipase A1 (PL-A1) and exopolysaccharide (EPS)-producing bacteria (separately and in combination) on the yield, microstructure, and texture of cheese. Four different cheeses were manufactured: cheese made with PL-A1, cheese made with EPS-producing bacteria, cheese with both PL-A1 and EPS-producing bacteria, and a cheese control without PL-A1 or EPS-producing bacteria. The compositional analysis of cheese was carried out using methods of AOAC International (Washington, DC). The actual yield and moisture-adjusted yield were calculated for all cheese treatments. Texture profile analyses of cheeses were performed using a texture analyzer. Micrographs were obtained by electron scanning microscopy. Fifty panelists carried out sensorial analysis using ranking tests. Incorporation of EPS-producing bacteria in the manufacture of cheese increased the moisture content and water activity. In contrast, the addition of PL-A1 did not increase fat retention or cheese yield. The use of EPS alone improved the cheese yield by increasing water and fat retention, but also caused a negative effect on the texture and flavor of Chihuahua cheese. The use of EPS-producing bacteria in combination with PL-A1 improved the cheese yield and increased the moisture and fat content. The cheeses with the best flavor and texture were those manufactured with PL-A1 and the cheeses manufactured with the combination of PL-A1 and EPS-producing culture.

  18. Morganella morganii bacteria produces phenol as the sex pheromone of the New Zealand grass grub from tyrosine in the colleterial gland

    Science.gov (United States)

    Marshall, D. G.; Jackson, T. A.; Unelius, C. R.; Wee, S. L.; Young, S. D.; Townsend, R. J.; Suckling, D. M.

    2016-08-01

    Costelytra zealandica (Coleoptera: Scarabeidae) is a univoltine endemic species that has colonised and become a major pest of introduced clover and ryegrass pastures that form about half of the land area of New Zealand. Female beetles were previously shown to use phenol as their sex pheromone produced by symbiotic bacteria in the accessory or colleterial gland. In this study, production of phenol was confirmed from the female beetles, while bacteria were isolated from the gland and tested for attractiveness towards grass grub males in traps in the field. The phenol-producing bacterial taxon was identified by partial sequencing of the 16SrRNA gene, as Morganella morganii. We then tested the hypothesis that the phenol sex pheromone is biosynthesized from the amino acid tyrosine by the bacteria. This was shown to be correct, by addition of isotopically labelled tyrosine (13C) to the bacterial broth, followed by detection of the labelled phenol by SPME-GCMS. Elucidation of this pathway provides specific evidence how the phenol is produced as an insect sex pheromone by a mutualistic bacteria.

  19. Morganella morganii bacteria produces phenol as the sex pheromone of the New Zealand grass grub from tyrosine in the colleterial gland.

    Science.gov (United States)

    Marshall, D G; Jackson, T A; Unelius, C R; Wee, S L; Young, S D; Townsend, R J; Suckling, D M

    2016-08-01

    Costelytra zealandica (Coleoptera: Scarabeidae) is a univoltine endemic species that has colonised and become a major pest of introduced clover and ryegrass pastures that form about half of the land area of New Zealand. Female beetles were previously shown to use phenol as their sex pheromone produced by symbiotic bacteria in the accessory or colleterial gland. In this study, production of phenol was confirmed from the female beetles, while bacteria were isolated from the gland and tested for attractiveness towards grass grub males in traps in the field. The phenol-producing bacterial taxon was identified by partial sequencing of the 16SrRNA gene, as Morganella morganii. We then tested the hypothesis that the phenol sex pheromone is biosynthesized from the amino acid tyrosine by the bacteria. This was shown to be correct, by addition of isotopically labelled tyrosine ((13)C) to the bacterial broth, followed by detection of the labelled phenol by SPME-GCMS. Elucidation of this pathway provides specific evidence how the phenol is produced as an insect sex pheromone by a mutualistic bacteria.

  20. The H2O2-H2O Hypothesis: Extremophiles Adapted to Conditions on Mars?

    Science.gov (United States)

    Houtkooper, Joop M.; Schulze-Makuch, Dirk

    2007-08-01

    The discovery of extremophiles on Earth is a sequence of discoveries of life in environments where it had been deemed impossible a few decades ago. The next frontier may be the Martian surface environment: could life have adapted to this harsh environment? What we learned from terrestrial extremophiles is that life adapts to every available niche where energy, liquid water and organic materials are available so that in principle metabolism and propagation are possible. A feasible adaptation mechanism to the Martian surface environment would be the incorporation of a high concentration of hydrogen peroxide in the intracellular fluid of organisms. The H2O2-H2O hypothesis suggests the existence of Martian organisms that have a mixture of H2O2 and H2O instead of salty water as their intracellular liquid (Houtkooper and Schulze-Makuch, 2007). The advantages are that the freezing point is low (the eutectic freezes at 56.5°C) and that the mixture is hygroscopic. This would enable the organisms to scavenge water from the atmosphere or from the adsorbed layers of water molecules on mineral grains, with H2O2 being also a source of oxygen. Moreover, below its freezing point the H2O2-H2O mixture has the tendency to supercool. Hydrogen peroxide is not unknown to biochemistry on Earth. There are organisms for which H2O2 plays a significant role: the bombardier beetle, Brachinus crepitans, produces a 25% H2O2 solution and, when attacked by a predator, mixes it with a fluid containing hydroquinone and a catalyst, which produces an audible steam explosion and noxious fumes. Another example is Acetobacter peroxidans, which uses H2O2 in its metabolism. H2O2 plays various other roles, such as the mediation of physiological responses such as cell proliferation, differentiation, and migration. Moreover, most eukaryotic cells contain an organelle, the peroxisome, which mediates the reactions involving H2O2. Therefore it is feasible that in the course of evolution, water-based organisms

  1. Quantitative fluorescent in-situ hybridization: a hypothesized competition mode between two dominant bacteria groups in hydrogen-producing anaerobic sludge processes.

    Science.gov (United States)

    Huang, C-L; Chen, C-C; Lin, C-Y; Liu, W-T

    2009-01-01

    Two hydrogen-producing continuous flow stirred tank reactors (CSTRs) fed respectively with glucose and sucrose were investigated by polymerase chain reaction-denatured gradient gel electrophoresis (PCR-DGGE) and fluorescent in-situ hybridization (FISH). The substrate was fed in a continuous mode decreased from hydraulic retention time (HRT) 10 hours to 6, 5, 4, 3, and 2 hours. Quantitative fluorescent in-situ hybridization (FISH) observations further demonstrated that two morphotypes of bacteria dominated both microbial communities. One was long rod bacteria which can be targeted either by Chis150 probe designed to hybridize the gram positive low G + C bacteria or the specific oligonucleotide probe Lg10-6. The probe Lg10-6, affiliated with Clostridium pasteurianum, was designed and then checked with other reference organisms. The other type, unknown group, which cannot be detected by Chis150 was curved rod bacteria. Notably, the population ratios of the two predominant groups reflected the different operational performance of the two reactors, such as hydrogen producing rates, substrate turnover rates and metabolites compositions. Therefore, a competition mode of the two dominant bacteria groups was hypothesized. In the study, 16S rRNA-based gene library of hydrogen-producing microbial communities was established. The efficiency of hydrogen yields was correlated with substrates (glucose or sucrose), HRT, metabolites compositions (acetate, propionate, butyrate and ethanol), thermal pre-treatment (seed biomass was heated at 100 degrees C for 45 minutes), and microbial communities in the bioreactor, not sludge sources (municipal sewage sludge, alcohol-processing sludge, or bean-processing sludge). The designed specific oligonucleotide probe Lg10-6 also provides us a useful and fast molecular tool to screen hydrogen-producing microbial communities in the future research.

  2. A novel H2S/H2O2 fuel cell operating at the room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Sanli, Ayse Elif [Gazi University (Turkey)], email: aecsanli@gmail.com; Aytac, Aylin [Department of Chemistry, Faculty of Science, Gazi University, Teknikokullar (Turkey)], email: aytaca@gazi.edu.tr

    2011-07-01

    This study concerns the oxidation mechanism of hydrogen sulfide and a fuel cell; acidic peroxide is used as the oxidant and basic hydrogen sulfide is the fuel. A solid state H2S/H2O2 stable fuel cell was produced at room temperature. A cell potential of 0.85 V was reached; this is quite remarkable in comparison to the H2S/O2 fuel cell potential of 0.85 V obtained at 850-1000 degree celsius. The hydrogen sulfide goes through an oxidation reaction in the alkaline fuel cell (H2S/H2O2 fuel cell) which opens up the possibility of using the cheaper nickel as a catalyst. As a result, the fuel cell becomes a potentially low cost technology. A further benefit from using H2S as the alkaline liquid H2S/H2O2 fuel cell, is that sulfide ions are oxidized at the anode, releasing electrons. Sulfur produced reacts with the other sulfide ions and forms disulfide and polysulfide ions in basic electrolytes (such as Black Sea water).

  3. The impact of antibiotic use on the incidence and resistance pattern of extended-spectrum beta-lactamase-producing bacteria in primary and secondary healthcare settings.

    Science.gov (United States)

    Aldeyab, Mamoon A; Harbarth, Stephan; Vernaz, Nathalie; Kearney, Mary P; Scott, Michael G; Darwish Elhajji, Feras W; Aldiab, Motasem A; McElnay, James C

    2012-07-01

    • The emergence and spread of bacteria producing extended-spectrum beta-lactamases (ESBLs) has important therapeutic and epidemiologic implications. • A key target for the establishment of hospital antibiotic stewardship is reducing the occurrence of additional antibiotic resistance. • Further research is needed to accumulate supporting evidence that reducing antibiotic use will result in a parallel reduction in antibiotic resistance. • Fluoroquinolone restriction reversed ciprofloxacin resistance in primary and secondary healthcare settings. • Fluoroquinolone restriction reduced ESBL-producing bacteria incidence rates in both the primary and secondary healthcare settings. • This study highlights the value of time-series analysis in designing efficient antibiotic stewardship. The objective of the present study was to study the relationship between hospital antibiotic use, community antibiotic use and the incidence of extended-spectrum beta-lactamase (ESBL)-producing bacteria in hospitals, while assessing the impact of a fluoroquinolone restriction policy on ESBL-producing bacteria incidence rates. The study was retrospective and ecological in design. A multivariate autoregressive integrated moving average (ARIMA) model was built to relate antibiotic use to ESB-producing bacteria incidence rates and resistance patterns over a 5 year period (January 2005-December 2009). Analysis showed that the hospital incidence of ESBLs had a positive relationship with the use of fluoroquinolones in the hospital (coefficient = 0.174, P= 0.02), amoxicillin-clavulanic acid in the community (coefficient = 1.03, P= 0.03) and mean co-morbidity scores for hospitalized patients (coefficient = 2.15, P= 0.03) with various time lags. The fluoroquinolone restriction policy was implemented successfully with the mean use of fluoroquinolones (mainly ciprofloxacin) being reduced from 133 to 17 defined daily doses (DDDs)/1000 bed days (P < 0.001) and from 0.65 to 0.54 DDDs/1000

  4. Stochastic modelling of Listeria monocytogenes single cell growth in cottage cheese with mesophilic lactic acid bacteria from aroma producing cultures

    DEFF Research Database (Denmark)

    Østergaard, Nina Bjerre; Christiansen, Lasse Engbo; Dalgaard, Paw

    2015-01-01

    for pH, lactic acid concentration and initial concentration of lactic acid bacteria. These data and bootstrap sampling were used to represent product variability in the stochastic model. Lag time data were estimated from observed growth data (lactic acid bacteria) and from literature on L. monocytogenes...... single cells. These lag time data were expressed as relative lag times and included in growth models. A stochastic model was developed from an existing deterministic growth model including the effect of five environmental factors and inter-bacterial interaction [Østergaard, N.B, Eklöw, A and Dalgaard, P....... 2014. Modelling the effect of lactic acid bacteria from starter- and aroma culture on growth of Listeria monocytogenes in cottage cheese. International Journal of Food Microbiology. 188, 15-25]. Growth of L. monocytogenes single cells, using lag time distributions corresponding to three different...

  5. Identificación Molecular de Bacterias Productoras de Polihidroxialcanoatos en Subproductos de Lácteos y Caña de Azúcar / Molecular Identification of Polyhydroxyalkanoate-Producing Bacteria Isolated from Dairy and Sugarcane Residues

    Directory of Open Access Journals (Sweden)

    Ana Carolina Cardona Echavarría

    2013-12-01

    Full Text Available Los polihidroxialcanoatos (PHAs son bioplásticostermoestables sintetizados por algunas bacterias, que losacumulan como reservas de carbono en forma de inclusiones citoplasmáticas. Estos compuestos se constituyen en una opción para la sustitución de polímeros sintéticos no biodegradables. En este trabajo se evaluó la presencia de bacterias productoras de PHAs en lactosueros derivados de la producción de quesos, y en melaza, cachaza y bagazo de caña de azúcar. El aislamiento bacteriano se realizó en medio mínimo de sales suplementadocon glucosa al 2% y 1 μL mL-1 de rojo Nilo (0,1%. Las colonias que presentaron fluorescencia a 340 nm en este medio, se evaluaron nuevamente mediante microscopía de fluorescenciacon azul Nilo. Aquellas cepas que resultaron positivas para ambaspruebas fueron consideradas como potenciales productoras de PHAs e identificadas por secuenciación de la región 16S del ADN ribosomal. Seguidamente se evaluó, en algunas de éstas, la presencia del gen phaC mediante PCR con cebadores específicos. Se detectaron 38 cepas productoras de PHAs, representando 18morfotipos bacterianos. Fueron identificadas en los sustratosde lactosuero cepas pertenecientes a los géneros Lactococcus, Klebsiella, Pseudomonas, Enterobacter y Enterococcus; mientras que en los subproductos de caña de azúcar se encontraron cepas de los géneros Bacillus, Enterobacter, Pantoea, Klebsiellay Gluconobacter. El gen phaC se detectó por PCR en 16 bacterias que presentaron los arreglos genéticos I y IV. Este trabajo abre la posibilidad de emplear las bacterias obtenidas en procesos alternativos, ambientalmente sostenibles y generadores de valoragregado, para la disposición final de subproductos y residuos agroindustriales. / Polyhydroxyalkanoates (PHAs are thermostable bioplastics produced by bacteria and stored as inclusion bodies to serve as a reserve carbon source. These compounds are a goodalternative to non-biodegradable synthetic plastics

  6. Biofilter for generation of concentrated sulphuric acid from H2S.

    Science.gov (United States)

    Rabbani, K A; Charles, W; Kayaalp, A; Cord-Ruwisch, R; Ho, G

    2016-08-01

    Biofilters are used for the conversion of odorous hydrogen sulphide to odourless sulphate in wastewater treatment plants under the right conditions of moisture and pH. One of the consequences of maintaining the suitable pH and moisture content is the production of large volumes of weakly acidic leachate. This paper presents a biofilter with a maximum H2S elimination capacity of 16.3 g m(-3) h(-1) and removal efficiency greater than 95 % which produces small volumes (1 mL of solution L(-1) of reactor day(-1)) of sulphuric acid with a concentration greater than 5.5 M after 150 days of continuous operation. The concentrated sulphuric acid was produced by intermittently trickling a minimum amount of nutrient solution down the upflow biofilter which created a moisture and pH gradient within the biofilter resulting in an environment at the top for the bacterial conversion of H2S, while sulphuric acid was accumulated at the base. Genetic diversity profiling of samples taken from different sections of the biofilter confirms that the upper sections of the biofilter had the best environment for the bacteria to convert H2S to sulphate. The formation of concentrated sulphuric acid presents an opportunity for the recovery of sulphur from the waste stream as a usable product.

  7. H2S, a novel gasotransmitter, involves in gastric accommodation.

    Science.gov (United States)

    Xiao, Ailin; Wang, Hongjuan; Lu, Xin; Zhu, Jianchun; Huang, Di; Xu, Tonghui; Guo, Jianqiang; Liu, Chuanyong; Li, Jingxin

    2015-11-04

    H2S is produced mainly by two enzymes:cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE), using L-cysteine (L-Cys) as the substrate. In this study, we investigated the role of H2S in gastric accommodation using CBS(+/-) mice, immunohistochemistry, immunoblot, methylene blue assay, intragastric pressure (IGP) recording and electrical field stimulation (EFS). Mouse gastric fundus expressed H2S-generating enzymes (CBS and CSE) and generated detectable amounts of H2S. The H2S donor, NaHS or L-Cys, caused a relaxation in either gastric fundus or body. The gastric compliance was significantly increased in the presence of L-Cys (1 mM). On the contrary, AOAA, an inhibitor for CBS, largely inhibited gastric compliance. Consistently, CBS(+/-) mice shows a lower gastric compliance. However, PAG, a CSE inhibitor, had no effect on gastric compliances. L-Cys enhances the non-adrenergic, non-cholinergic (NANC) relaxation of fundus strips, but AOAA reduces the magnitude of relaxations to EFS. Notably, the expression level of CBS but not CSE protein was elevated after feeding. Consistently, the production of H2S was also increased after feeding in mice gastric fundus. In addition, AOAA largely reduced food intake and body weight in mice. Furthermore, a metabolic aberration of H2S was found in patients with functional dyspepsia (FD). In conclusion, endogenous H2S, a novel gasotransmitter, involves in gastric accommodation.

  8. dpr and sod in Streptococcus mutans are involved in coexistence with S. sanguinis, and PerR is associated with resistance to H2O2.

    Science.gov (United States)

    Fujishima, Kei; Kawada-Matsuo, Miki; Oogai, Yuichi; Tokuda, Masayuki; Torii, Mitsuo; Komatsuzawa, Hitoshi

    2013-03-01

    Large numbers of bacteria coexist in the oral cavity. Streptococcus sanguinis, one of the major bacteria in dental plaque, produces hydrogen peroxide (H(2)O(2)), which interferes with the growth of other bacteria. Streptococcus mutans, a cariogenic bacterium, can coexist with S. sanguinis in dental plaque, but to do so, it needs a means of detoxifying the H(2)O(2) produced by S. sanguinis. In this study, we investigated the association of three oxidative stress factors, Dpr, superoxide dismutase (SOD), and AhpCF, with the resistance of S. sanguinis to H(2)O(2). The knockout of dpr and sod significantly increased susceptibility to H(2)O(2), while the knockout of ahpCF had no apparent effect on susceptibility. In particular, dpr inactivation resulted in hypersensitivity to H(2)O(2). Next, we sought to identify the factor(s) involved in the regulation of these oxidative stress genes and found that PerR negatively regulated dpr expression. The knockout of perR caused increased dpr expression levels, resulting in low-level susceptibility to H(2)O(2) compared with the wild type. Furthermore, we evaluated the roles of perR, dpr, and sod when S. mutans was cocultured with S. sanguinis. Culturing of the dpr or sod mutant with S. sanguinis showed a significant decrease in the S. mutans population ratio compared with the wild type, while the perR mutant increased the ratio. Our results suggest that dpr and sod in S. mutans are involved in coexistence with S. sanguinis, and PerR is associated with resistance to H(2)O(2) in regulating the expression of Dpr.

  9. Histamine H2 receptor - Involvement in gastric ulceration

    Science.gov (United States)

    Brown, P. A.; Vernikos-Danellis, J.; Brown, T. H.

    1976-01-01

    The involvement of the H1 and H2 receptors for histamine in the pathogenesis of gastric ulcers was investigated in rats. Metiamide, an H2 receptor antagonist, reliably reduced ulceration produced by stress alone or by a combination of stress and aspirin. In contrast, pyrilamine, which blocks only the H1 receptor, was without effect under these same conditions. The results support the hypothesis that histamine mediates both stress and stress plus aspirin induced ulceration by a mechanism involving the H2 receptor.

  10. Histamine H2 receptor - Involvement in gastric ulceration

    Science.gov (United States)

    Brown, P. A.; Vernikos-Danellis, J.; Brown, T. H.

    1976-01-01

    The involvement of the H1 and H2 receptors for histamine in the pathogenesis of gastric ulcers was investigated in rats. Metiamide, an H2 receptor antagonist, reliably reduced ulceration produced by stress alone or by a combination of stress and aspirin. In contrast, pyrilamine, which blocks only the H1 receptor, was without effect under these same conditions. The results support the hypothesis that histamine mediates both stress and stress plus aspirin induced ulceration by a mechanism involving the H2 receptor.

  11. Novel ferulate esterase from Gram-positive lactic acid bacteria and analyses of the recombinant enzyme produced in E. coli

    Science.gov (United States)

    Using a plate containing ethyl ferulate as sole carbon source, various bacteria cultures were screened for ferulate esterase (FAE). Among a dozen of species showing positive FAE, one Lactobacillus fermentum strain NRRL 1932 demonstrated the strongest activity. Using a published sequence of ferulate ...

  12. Interpolatory Weighted-H2 Model Reduction

    CERN Document Server

    Anic, Branimir; Gugercin, Serkan; Antoulas, Athanasios C

    2012-01-01

    This paper introduces an interpolation framework for the weighted-H2 model reduction problem. We obtain a new representation of the weighted-H2 norm of SISO systems that provides new interpolatory first order necessary conditions for an optimal reduced-order model. The H2 norm representation also provides an error expression that motivates a new weighted-H2 model reduction algorithm. Several numerical examples illustrate the effectiveness of the proposed approach.

  13. Crystal structures of heterotypic nucleosomes containing histones H2A.Z and H2A.

    Science.gov (United States)

    Horikoshi, Naoki; Arimura, Yasuhiro; Taguchi, Hiroyuki; Kurumizaka, Hitoshi

    2016-06-01

    H2A.Z is incorporated into nucleosomes located around transcription start sites and functions as an epigenetic regulator for the transcription of certain genes. During transcriptional regulation, the heterotypic H2A.Z/H2A nucleosome containing one each of H2A.Z and H2A is formed. However, previous homotypic H2A.Z nucleosome structures suggested that the L1 loop region of H2A.Z would sterically clash with the corresponding region of canonical H2A in the heterotypic nucleosome. To resolve this issue, we determined the crystal structures of heterotypic H2A.Z/H2A nucleosomes. In the H2A.Z/H2A nucleosome structure, the H2A.Z L1 loop structure was drastically altered without any structural changes of the canonical H2A L1 loop, thus avoiding the steric clash. Unexpectedly, the heterotypic H2A.Z/H2A nucleosome is more stable than the homotypic H2A.Z nucleosome. These data suggested that the flexible character of the H2A.Z L1 loop plays an essential role in forming the stable heterotypic H2A.Z/H2A nucleosome.

  14. Characterization of N-acyl homoserine lactones (AHLs) producing bacteria isolated from vacuum-packaged refrigerated turbot (Scophthalmus maximus) and possible influence of exogenous AHLs on bacterial phenotype.

    Science.gov (United States)

    Zhang, Caili; Zhu, Suqin; Jatt, Abdul-Nabi; Zeng, Mingyong

    2016-01-01

    Quorum sensing (QS) is a cell-to-cell communication mechanism through which microbial cells communicate and regulate their wide variety of biological activities. N-acyl homoserine lactones (AHLs) are considered to be the most important QS signaling molecules produced by several Gram-negative bacteria. The present study aimed to screen the AHLs-producing bacteria from spoiled vacuum-packaged refrigerated turbot (Scophthalmus maximus) by biosensor assays, and the profiles of AHLs produced by these bacteria were determined using reversed-phase thin-layer chromatography (RP-TLC) and gas chromatography-mass spectrometry (GC-MS). Effects of exogenous AHLs and QS inhibitor (QSI) on the phenotypes (i.e., extracellular proteolytic activity and biofilm formation) of the AHLs-producing bacteria were also evaluated. Our results demonstrated that eight out of twenty-two isolates were found to produce AHLs. Three of the AHLs-producing isolates were identified as Serratia sp., and the other five were found to belong to the family of Aeromonas. Two isolates (i.e., S. liquefaciens A2 and A. sobria B1) with higher AHLs-producing activities were selected for further studies. Mainly, RP-TLC and GC-MS analysis revealed three AHLs, i.e., 3-oxo-C6-HSL, C8-HSL and C10-HSL were produced by S. liquefaciens A2, while five AHLs, i.e., C4-HSL, C6-HSL, C8-HSL, C10-HSL, and C12-HSL, were produced by A. sobria B1. Moreover, production of AHLs in both bacterial strains were found to be density-dependent, and the AHLs activity reached a maximum level in their middle logarithmic phase and decreased in the stationary phase. The addition of exogenous AHLs and QSI decreased the specific protease activity both of the Serratia A2 and Aeromonas B1. Exogenous AHLs inhibited the biofilm formation of Serratia A2 while it enhanced the biofilm formation in Aeromonas B1. QSI inhibited the specific protease activity and biofilm formation in both bacterial strains.

  15. Cross-Feeding between Bifidobacterium longum BB536 and Acetate-Converting, Butyrate-Producing Colon Bacteria during Growth on Oligofructose▿

    OpenAIRE

    Falony, Gwen; Vlachou, Angeliki; Verbrugghe, Kristof; De Vuyst, Luc

    2006-01-01

    In vitro coculture fermentations of Bifidobacterium longum BB536 and two acetate-converting, butyrate-producing colon bacteria, Anaerostipes caccae DSM 14662 and Roseburia intestinalis DSM 14610, with oligofructose as the sole energy source, were performed to study interspecies interactions. Two clearly distinct types of cross-feeding were identified. A. caccae DSM 14662 was not able to degrade oligofructose but could grow on the fructose released by B. longum BB536 during oligofructose break...

  16. Hydrogen-producing microflora and Fe-Fe hydrogenase diversities in seaweed bed associated with marine hot springs of Kalianda, Indonesia.

    Science.gov (United States)

    Xu, Shou-Ying; He, Pei-Qing; Dewi, Seswita-Zilda; Zhang, Xue-Lei; Ekowati, Chasanah; Liu, Tong-Jun; Huang, Xiao-Hang

    2013-05-01

    Microbial fermentation is a promising technology for hydrogen (H(2)) production. H(2) producers in marine geothermal environments are thermophilic and halotolerant. However, no one has surveyed an environment specifically for thermophilic bacteria that produce H(2) through Fe-Fe hydrogenases (H(2)ase). Using heterotrophic medium, several microflora from a seaweed bed associated with marine hot springs were enriched and analyzed for H(2) production. A H(2)-producing microflora was obtained from Sargassum sp., 16S rRNA genes and Fe-Fe H(2)ase diversities of this enrichment were also analyzed. Based on 16S rRNA genes analysis, 10 phylotypes were found in the H(2)-producing microflora showing 90.0-99.5 % identities to known species, and belonged to Clostridia, Gammaproteobacteria, and Bacillales. Clostridia were the most abundant group, and three Clostridia phylotypes were most related to known H(2) producers such as Anaerovorax odorimutans (94.0 % identity), Clostridium papyrosolvens (98.4 % identity), and Clostridium tepidiprofundi (93.1 % identity). For Fe-Fe H(2)ases, seven phylotypes were obtained, showing 63-97 % identities to known Fe-Fe H(2)ases, and fell into four distinct clusters. Phylotypes HW55-3 and HM55-1 belonged to thermophilic and salt-tolerant H(2)-producing Clostridia, Halothermothrix orenii-like Fe-Fe H(2)ases (80 % identity), and cellulolytic H(2)-producing Clostridia, C. papyrosolvens-like Fe-Fe H(2)ases (97 % identity), respectively. The results of both 16S rRNA genes and Fe-Fe H(2)ases surveys suggested that the thermophilic and halotolerant H(2)-producing microflora in seaweed bed of hot spring area represented previously unknown H(2) producers, and have potential application for H(2) production.

  17. The impact of antibiotic use on the incidence and resistance pattern of extended-spectrum beta-lactamase-producing bacteria in primary and secondary healthcare settings

    Science.gov (United States)

    Aldeyab, Mamoon A; Harbarth, Stephan; Vernaz, Nathalie; Kearney, Mary P; Scott, Michael G; Darwish Elhajji, Feras W; Aldiab, Motasem A; McElnay, James C

    2012-01-01

    AIMS The objective of the present study was to study the relationship between hospital antibiotic use, community antibiotic use and the incidence of extended-spectrum beta-lactamase (ESBL)-producing bacteria in hospitals, while assessing the impact of a fluoroquinolone restriction policy on ESBL-producing bacteria incidence rates. METHODS The study was retrospective and ecological in design. A multivariate autoregressive integrated moving average (ARIMA) model was built to relate antibiotic use to ESB-producing bacteria incidence rates and resistance patterns over a 5 year period (January 2005–December 2009). RESULTS Analysis showed that the hospital incidence of ESBLs had a positive relationship with the use of fluoroquinolones in the hospital (coefficient = 0.174, P = 0.02), amoxicillin-clavulanic acid in the community (coefficient = 1.03, P = 0.03) and mean co-morbidity scores for hospitalized patients (coefficient = 2.15, P = 0.03) with various time lags. The fluoroquinolone restriction policy was implemented successfully with the mean use of fluoroquinolones (mainly ciprofloxacin) being reduced from 133 to 17 defined daily doses (DDDs)/1000 bed days (P antibiotic restriction. The study also highlights the potential value of the time-series analysis in designing efficient antibiotic stewardship. PMID:22150975

  18. Extended-spectrum beta-lactamase-producing bacteria in a tertiary care hospital in Madrid: epidemiology, risk factors and antimicrobial susceptibility patterns

    Directory of Open Access Journals (Sweden)

    Ines Rubio-Perez

    2012-07-01

    Full Text Available Introduction: Extended-spectrum beta-lactamase (ESBL producing bacteria have been increasingly reported as causal agents of nosocomial infection worldwide. Resistance patterns vary internationally, and even locally, from one institution to the other. We investigated the clinical isolates positive for ESBL-producing bacteria in our institution, a tertiary care hospital in Madrid (Spain, during a 2-year period (2007–2008. Methods: Clinical and microbiological data were retrospectively reviewed. Two hundred and nineteen patients were included in the study. Results: Advanced age, diabetes, use of catheters, previous hospitalization and previous antibiotic treatment were some of the risk factors found among patients. Escherichia coli was the most frequent isolate, and urinary tract the most common site of isolation. Internal Medicine, Intensive Care Unit (ICU and General Surgery presented the highest number of isolates. There were no outbreaks during the study period. Antibiotic patterns showed high resistance rates to quinolones in all isolates. There was 100% sensitivity to carbapenems. Conclusion: Carbapenems continue to be the treatment of choice for ESBL-producing bacteria. Infection control measures are of great importance to avoid the spread of these nosocomial infections.

  19. He*(23S) Penning ionization of H2S. I. Theoretical Franck-Condon factors for the H2S(X̃ 1A1, v′ = 0)→H2S+ (X̃2B1, Ã2A1) ionization and H2S+(Ã-X̃) transition

    OpenAIRE

    Tokue, Ikuo; Yamasaki, Katsuyoshi; Nanbu, Shinkoh

    2003-01-01

    In order to elucidate the ionization dynamics, in particular the vibrational distribution, of H2S+(A˜ ) produced by the Penning ionization of H2S with He*(2 3S) atoms, the Franck–Condon factors (FCFs) were presented for the H2S(X˜ )!H2S+(X˜ ,A˜ ) ionization and the H2S+(A˜ –X˜ ) transition, and Einstein's A coefficients were presented for the latter transition. The FCFs were obtained by quantum vibrational calculations using the global potential energy surfaces (PESs) of H2S(X˜ 1A1) and H2S+(...

  20. Comparison of four phenotypic methods for detection of metallo-β-lactamase-producing Gram-negative bacteria in rural teaching hospital

    Science.gov (United States)

    Panchal, Chinjal A.; Oza, Sweta Sunil; Mehta, Sanjay J.

    2017-01-01

    CONTEXT: Metallo-β-lactamase (MBL)-producing bacteria lead to resistance to carbapenem an antibiotic that used as the last resort for treatment of multidrug-resistant bacteria, extended spectrum beta-lactamases, and AmpC β-lactamase-producing Gram-negative bacteria (GNB). The emergence of MBL-producing GNB is challenge to microbiology laboratories because there are no standardized guidelines available to detect them. The aim of this study was to compare four phenotypic methods to detect MBL production in GNB and to determine antibiotic sensitivity of MBL-producing isolates. MATERIALS AND METHODS: A total of 107 clinical isolates of GNB were tested for MBL production. Imipenem (IPM)-resistant GNB were taken as positive for MBL screening. MBL detection was done using ethylene diamine tetra acetic acid (EDTA) as MBL inhibitor. Four phenotypic methods were evaluated: (1) Combined disk synergy test (CDST) with 0.5M EDTA (CDST-0.5 M EDTA), (2) CDST with 0.1 M EDTA (CDST-0.1 M EDTA), (3) double-disk synergy test (DDST) with 0.5M EDTA (DDST-0.5 M EDTA), and (4) DDST with 0.1 M EDTA (DDST-0.1 M EDTA). RESULTS: Out of 107 GNB, 30 were resistant to IPM considered as screening positive. Out of 30, 21 (70%) isolates were MBL positive by CDST-0.1 M EDTA, 19 (63.33%) by CDST-0.5M EDTA, 17 (56.67%) by DDST-0.1 M EDTA, and 16 (53.33%) by DDST-0.5M EDTA. All MBL-producing Gram-negative Bacilli were resistant to ampicillin/sulbactam. Polymyxin B was found to be the most sensitive drug. CONCLUSION: CDST-0.1 M EDTA is the most sensitive method MBL detection. The detection of MBL-producing GNB is very important to control spread of the resistance. PMID:28367020

  1. Quantification of Growth of Campylobacter and Extended Spectrum β-Lactamase Producing Bacteria Sheds Light on Black Box of Enrichment Procedures.

    Science.gov (United States)

    Hazeleger, Wilma C; Jacobs-Reitsma, Wilma F; den Besten, Heidy M W

    2016-01-01

    Campylobacter is well recognized as the leading cause of bacterial foodborne diarrheal disease worldwide, and is routinely found in meat originating from poultry, sheep, pigs, and cattle. Effective monitoring of Campylobacter contamination is dependent on the availability of reliable detection methods. The method of the International Organization for Standardization for the detection of Campylobacter spp. in food (ISO 10272-1:2006) recommends the use of Bolton broth (BB) as selective enrichment medium, including a pre-enrichment step of 4-6 h at 37°C to revive sublethally damaged cells prior to incubation for 2 days at 41.5°C. Recently the presence of abundantly growing extended spectrum β-lactamase producing Enterobacteriaceae (ESBL bacteria) has become one of the most important factors that interfere with the isolation of Campylobacter, resulting in false-negative detection. However, detailed growth dynamics of Campylobacter and its competitors remain unclear, where these would provide a solid base for further improvement of the enrichment procedure for Campylobacter. Other enrichment broths, such as Preston broth (PB) and BB plus clavulanic acid (BBc) have been suggested to inhibit competitive flora. Therefore, these different broths were used as enrichments to measure the growth kinetics of several strains of Campylobacter jejuni and ESBL bacteria separately, in co-culture and of strains in chicken samples. The maximum cell numbers and often the growth rates of Campylobacter in mixed culture with ESBL bacteria were significantly lower than in single cultures, indicating severe suppression of Campylobacter by ESBL bacteria, also in naturally contaminated samples. PB and BBc successfully diminished ESBL bacteria and might therefore be a better choice as enrichment medium in possibly ESBL-bacteria contaminated samples. The efficacy of a pre-enrichment step in the BB ISO-procedure was not supported for cold-stressed and non-stressed cells. Therefore, omission of

  2. Effects of hydrogen sulfide (H2S) on respiration control of state 3/4 in ...

    African Journals Online (AJOL)

    hope&shola

    2012-03-13

    Mar 13, 2012 ... Hydrogen sulfide (H2S) could availably regulate electron transport in the inner membrane of mitochondria from ..... electrons and two protons) would produce polysulfide or elemental sulfur. ... The relationship between H2S ...

  3. Screening of Rhizosphere Bacteria From Rice Fields in The Coastal Area as Acc-Deaminase and Auxin Producer

    Directory of Open Access Journals (Sweden)

    Annisyia Zarina Putri

    2015-02-01

    Full Text Available Salinity and drought stress results in the production of ethylene. Rhizosphere bacterial activity suppresses the production of ethylene through the activity of 1-aminocycopropane-1-carboxylate (ACC deaminase. In this study,a sampel of rhizosphere bacteria from coastal rice plant area was tested. The method used was acc deaminase activity test performed on Dworkin - Foster (DF media and PCR acdS gene using specific primers of ACC and a quantitative analysis of the production of auxin (IAA. Of 47 isolatees obtained, 8 were positively have acdS activity. The positive result was indicated by the presence of 1080 bp amplicon. Quantitative analysisshowed the highest yield of 10.6 ppm of auxin. The results prove that there are some bacteria originated from coastal rice plant area which have acc deaminase activity.

  4. Characterization of non-starter lactic acid bacteria in traditionally produced home-made Radan cheese during ripening

    Directory of Open Access Journals (Sweden)

    Jokovic Natasa

    2011-01-01

    Full Text Available Two hundred thirteen non-starter lactic acid bacteria isolated from Radan cheese during ripening were identified with both a classical biochemical test and rep-PCR with (GTG5 primer. For most isolates, which belong to the Lactococcus lactis subsp. lactis, Leuconostoc mesenteroides, Lactobacillus plantarum, Lactobacillus paraplantarum and Enterococcus faecium, a phenotypic identification was in good agreement with rep-PCR identification. Lactococeus lactis subsp. lactis, Enterococcus faecium and subspecies from the Lenconostoc mesenteroides group were the dominant population of lactic acid bacteria in cheese until 10 days of ripening and only one Streptococcus thermophilus strain was isolated from the 5-day-old cheese sample. As ripening progressed, Lactobacillus plantarum became the predominant species together with the group of heterofermentative species of lactobacilli that could not be precisely identified with rep-PCR.

  5. Chemical characterization of the gels produced by the diazotrophic bacteria Rhizobium tropici and Mesorhizobium sp; Caracterizacao quimica dos geis produzidos pelas bacterias diazotroficas Rhizobium tropici e Mesorhizobium sp.

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, Nilson Kobori [Departamento de Engenharia e Tecnologia de Alimentos, Instituto de Biociencias, Letras e Ciencias Exatas, Universidade Estadual Paulista, Sao Jose do Rio Preto - SP (Brazil); Aranda-Selverio, Gabriel; Exposti, Diego Tadeu Degli; Silva, Maria de Lourdes Corradi da [Departamento de Fisica, Quimica e Biologia, Faculdade de Ciencias e Tecnologia, Universidade Estadual Paulista, Presidente Prudente - SP (Brazil); Lemos, Eliana Gertrudes Macedo; Campanharo, Joao Carlos [Departamento de Tecnologia, Faculdade de Ciencias Agrarias e Veterinaria, Universidade Estadual Paulista, Jaboticabal - SP (Brazil); Silveira, Joana Lea Meira [Departamento de Bioquimica e Biologia Molecular, Universidade Federal do Parana, Curitiba - PR (Brazil)

    2012-07-01

    The exopolysaccharides with characteristics of gel produced by Rhizobium tropici (EPSRT) and Mesorhizobium sp (EPSMR) are acidic heteropolysaccharide composed mainly of glucose and galactose in a molar ratio of 4:1 and 5:1 respectively, with traces of mannose ({approx} 1%). Chemical analysis showed the presence of uronic acid, pyruvate and acetyl-substituents in the structures of both polymers. Experiments of gel permeation chromatography and polyacrylamide gel electrophoresis showed that EPSRT and EPSMR are homogeneous molecules with low grade of polydispersity. The EPS were characterized using spectroscopic techniques of FT-IR, {sup 1}H and {sup 13}C-NMR. (author)

  6. Inhibition of food-related bacteria by antibacterial substances produced by Pseudomonas sp. strains isolated from pasteurized milk

    OpenAIRE

    Ana Beatriz Ferreira Rangel; Jean Thiago Alves Soares; Mariana Maciel Pereira; Bruna Rachel de Britto Peçanha; Leonardo Emanuel de Oliveira Costa; Janaína dos Santos Nascimento

    2013-01-01

    In this work, the production of antimicrobial substances by strains of Pseudomonas sp. isolated from pasteurized milk and their potential action against food-related bacteria were investigated. Samples of pasteurized milk were purchased from arbitrarily chosen commercial establishments in the city of Rio de Janeiro, Brazil. Of the four samples analyzed, three presented several typical colonies of Pseudomonas. About 100 colonies were chosen and subjected to biochemical tests for confirmation o...

  7. Characterization of multi-drug resistant ESBL producing nonfermenter bacteria isolated from patients blood samples using phenotypic methods in Shiraz (Iran

    Directory of Open Access Journals (Sweden)

    Maneli Amin Shahidi

    2015-10-01

    Full Text Available Background and Aim: The emergence of  nonfermenter bacteria that are resistant to multidrug resistant ESBL  are  nowadays a principal problem  for hospitalized patients. The present study aimed at surveying the emergence of nonfermenter bacteria resistant to multi-drug ESBL producing isolated from patients blood samples using BACTEC 9240 automatic system in Shiraz. Materials and Methods: In this cross-sectional study, 4825 blood specimens were collected from hospitalized patients in Shiraz (Iran, and positive samples were detected by means of  BACTEC 9240 automatic system. The isolates  containing nonfermenter bacteria were identified based on biochemical tests embedded in the API-20E system. Antibiotic sensitivity  test was performed  and identification of  ESBL producing strains were done  using phenotypic detection of extended spectrum beta-lactamase producing isolates(DDST according to CLSI(2013 guidelines.   Results: Out of 4825 blood samples, 1145 (24% specimen were gram-positive using BACTEC system. Among all isolated microorganisms, 206 isolates were non-fermenting gram- negative bacteria. The most common non-fermenter isolates were Pseudomonas spp. (48%, Acinetobacter spp. (41.7% ,and Stenotrophomonas spp. (8.2%. Seventy of them (81.4% were  Acinetobacter spp. which were ESBL positive. Among &beta-lactam antibiotics, Pseudomonas spp. showed  the best sensitivity to piperacillin-tazobactam (46.5%.  Conclusion: It was found that  &beta-lactam antibiotics are not effective against more than 40% of Pseudomonas spp. infections and 78% Acinetobacter infections. Emergence of multi-drug resistant strains that are resistant to most antibiotic classes is a major public health problem in Iran. To resolve this problem using of practical guidelines is critical.

  8. Presence of acylated homoserine lactones (AHLs) and AHL-producing bacteria in meat and potential role of AHL in spoilage of meat

    DEFF Research Database (Denmark)

    Bruhn, Jesper Bartholin; Christensen, Allan Beck; Flodgaard, Lars

    2004-01-01

    ) analysis confirmed the presence of OHHL in pure cultures of H. alvei. Vacuum-packed meat spoiled at the same rate when inoculated with the H. alvei wild type compared to a corresponding AHL-lacking mutant. Addition of specific QS inhibitors to the AHL-producing H. alvei inoculated in meat or to naturally......Quorum-sensing (QS) signals (N-acyl homoserine lactones [AHLs]) were extracted and detected from five commercially produced vacuum-packed meat samples. Ninety-six AHL-producing bacteria were isolated, and 92 were identified as Enterobacteriaceae. Hafnia alvei was the most commonly identified AHL......-producing bacterium. Thin-layer chromatographic profiles of supernatants from six H. alvei isolates and of extracts from spoiling meat revealed that the major AHL species had an R-f value and shape similar to N-3-oxo-hexanoyl homoserine lactone (OHHL). Liquid chromatography-mass spectrometry (MS) (high-resolution MS...

  9. Evaluation of the Synergistic Effect of Mixed Cultures of White-Rot Fungus Pleurotus ostreatus and Biosurfactant-Producing Bacteria on DDT Biodegradation.

    Science.gov (United States)

    Purnomo, Adi Setyo; Ashari, Khoirul; Hermansyah, Farizha Triyogi

    2017-07-28

    DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane) is one of the organic synthetic pesticides that has many negative effects for human health and the environment. The purpose of this study was to investigate the synergistic effect of mixed cutures of white-rot fungus, Pleurotus ostreatus, and biosurfactant-producing bacteria, Pseudomonas aeruginosa and Bacillus subtilis, on DDT biodegradation. Bacteria were added into the P. ostreatus culture (mycelial wet weight on average by 8.53 g) in concentrations of 1, 3, 5, and 10 ml (1 ml ≈ 1.25 × 10(9) bacteria cells/ml culture). DDT was degraded to approximately 19% by P. ostreatus during the 7-day incubation period. The principal result of this study was that the addition of 3 ml of P. aeruginosa into P. ostreatus culture gave the highest DDT degradation rate (approximately 86%) during the 7-day incubation period. This mixed culture combination of the fungus and bacteria also gave the best ratio of optimization of 1.91. DDD (1,1-dichloro-2,2-bis(4-chlorophenyl) ethane), DDE (1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene), and DDMU (1-chloro-2,2-bis(4-chlorophenyl) ethylene) were detected as metabolic products from the DDT degradation by P. ostreatus and P. aeruginosa. The results of this study indicate that P. aeruginosa has a synergistic relationship with P. ostreatus and can be used to optimize the degradation of DDT by P. ostreatus.

  10. Antibiotics produced by marine bacteria and the evaluation of their activity; Kaiyo saikin no seisansuru kosei busshitsu to sono kassei hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, K.

    1997-09-10

    Researches continue into physiologically active substances metabolized by marine bacteria and, in this report, some that exhibit antibacterial activity (antibiotics) are introduced. A detailed description is given of a new, peculiar antibiotic named Koromicin discovered in this project. Since a number of terrestrial bacteria have already been investigated, marine halophiles, especially those adhering to large seaweed in eutrophic environments, are taken up in this paper. This is because they are easy to culture. Many are collected in Japan and South-Sea islands, and some are selected for culture in view of their capability for producing active substances. Active compounds are extracted from them, refined, isolated, and their structures are determined. It is found that many of the thus-obtained compounds are those that have already been isolated from marine creatures in the past, but this verifies the effectiveness of selecting the marine bacteria as the source from which to collect physiologically active substances. Koromicin discovered in this process is unique in that it impedes the growth of marine Gram-negative bacteria only. 11 refs., 4 figs., 2 tabs.

  11. H2S concentrations in the heart after acute H2S administration: methodological and physiological considerations.

    Science.gov (United States)

    Sonobe, Takashi; Haouzi, Philippe

    2016-12-01

    In this study, we have tried to characterize the limits of the approach typically used to determine H2S concentrations in the heart based on the amount of H2S evaporating from heart homogenates-spontaneously, after reaction with a strong reducing agent, or in a very acidic solution. Heart homogenates were prepared from male rats in control conditions or after H2S infusion induced a transient cardiogenic shock (CS) or cardiac asystole (CA). Using a method of determination of gaseous H2S with a detection limit of 0.2 nmol, we found that the process of homogenization could lead to a total disappearance of free H2S unless performed in alkaline conditions. Yet, after restoration of neutral pH, free H2S concentration from samples processed in alkaline and nonalkaline milieus were similar and averaged ∼0.2-0.4 nmol/g in both control and CS homogenate hearts and up to 100 nmol/g in the CA group. No additional H2S was released from control, CS, or CA hearts by using the reducing agent tris(2-carboxyethyl)phosphine or a strong acidic solution (pH H2S from combined pools. Of note, the reducing agent DTT produced a significant sulfide artifact and was not used. These data suggest that 1) free H2S found in heart homogenates is not a reflection of H2S present in a "living" heart and 2) the pool of combined sulfides, released in a strong reducing or acidic milieu, does not increase in the heart in a measurable manner even after toxic exposure to sulfide. Copyright © 2016 the American Physiological Society.

  12. Laboratory studies of H2SO4/H2O binary homogeneous nucleation from the SO2+OH reaction: evaluation of the experimental setup and preliminary results

    Directory of Open Access Journals (Sweden)

    M. Kulmala

    2008-08-01

    Full Text Available Binary homogeneous nucleation (BHN of sulphuric acid and water (H2SO4/H2O is one of the most important atmospheric nucleation processes, but laboratory observations of this nucleation process are very limited and there are also large discrepancies between different laboratory studies. The difficulties associated with these experiments include wall loss of H2SO4 and uncertainties in estimation of H2SO4 concentration ([H2SO4] involved in nucleation. We have developed a new laboratory nucleation setup to study H2SO4/H2O BHN kinetics and provide relatively constrained [H2SO4] needed for nucleation. H2SO4 is produced from the SO2+OH→HSO3 reaction and OH radicals are produced from water vapor UV absorption. The residual [H2SO4] were measured at the end of the nucleation reactor with a chemical ionization mass spectrometer (CIMS. Wall loss factors (WLFs of H2SO4 were estimated by assuming that wall loss is diffusion limited and these calculated WLFs were in good agreement with simultaneous measurements of the initial and residual [H2SO4] with two CIMSs. The nucleation zone was estimated from numerical simulations based on the measured aerosol sizes (particle diameter, Dp and [H2SO4]. The measured BHN rates (J ranged from 0.01–220 cm−3 s−1 at the initial and residual [H2SO4] from 108−1010 cm−3, a temperature of 288 K and relative humidity (RH from 11–23%; J increased with increasing [H2SO4] and RH. J also showed a power dependence on [H2SO4] with the exponential power of 3–8. These power dependences are consistent with other laboratory studies under similar [H2SO4] and RH, but different from atmospheric field observations which showed that particle number concentrations are often linearly dependent on [H2SO4]. These results, together with a higher [H2SO4] threshold (108–109 cm−3 needed to produce the unit J measured from the laboratory studies compared to the atmospheric conditions (106–107 cm−3, imply that H2SO4/H2O BHN alone is

  13. Detection and Antibiotic Susceptibility Pattern of Biofilm Producing Gram Positive and Gram Negative Bacteria Isolated From a Tertiary Care Hospital of Pakistan

    Directory of Open Access Journals (Sweden)

    Iqbal, M.

    2011-01-01

    Full Text Available Microorganisms adhere to non-living material or living tissue, and form biofilms made up of extracellular polymers/slime. Biofilm-associated microorganisms behave differently from free-floating bacteria with respect to growth rates and ability to resist antimicrobial treatments and therefore pose a public health problem. The objective of this study is to detect the prevalence of biofilm producers among Gram positive and Gram negative bacteria isolated from clinical specimens, and to study their antimicrobial susceptibility pattern. The study was carried out from October 2009 to March 2010, at the Department of Microbiology, Army Medical College/ National University of Sciences and Technology (NUST, Rawalpindi, Pakistan. Clinical specimens were received from various wards of a tertiary care hospital. These were dealt by standard microbiological procedures. Gram positive and Gram negative bacteria isolated were subjected to biofilm detection by congo red agar method (CRA. Antimicrobial susceptibility testing of those isolates, which showed positive results (slime production, was done according to the Kirby-Bauer disc diffusion technique. A total of 150 isolates were tested for the production of biofilm/slime. Among them, 81 isolates showed positive results. From these 81, 51 were Gram positive and 30 were Gram negative. All the 81(54% slime producers showed reduced susceptibility to majority of antibiotics. Bacterial biofilms are an important virulence factor associated with chronic nosocomial infection. Detection of biofilm forming organisms can help in appropriate antibiotic choice.

  14. The role of H2S bioavailability in endothelial dysfunction

    Science.gov (United States)

    Wang, Rui; Szabo, Csaba; Ichinose, Fumito; Ahmed, Asif; Whiteman, Matthew; Papapetropoulos, Andreas

    2015-01-01

    Endothelial dysfunction reflects pathophysiological changes in the phenotype and functions of endothelial cells that result from and/or contribute to a plethora of cardiovascular diseases. Here we review the role of hydrogen sulfide (H2S) in the pathogenesis of endothelial dysfunction, one of the fastest advanced and hottest research topics. Conventionally treated as an environment pollutant, H2S is also produced in endothelial cells and participates in the fine regulation of endothelial integrity and functions. Disturbed H2S bioavailability has been suggested to be a novel indicator of the progress and prognosis of endothelial dysfunction. Endothelial dysfunction appears to exhibit in different forms in different pathologies but therapeutics aimed at remedying the altered H2S bioavailability may benefit all. PMID:26071118

  15. Siderophore-Producing Bacteria from a Sand Dune Ecosystem and the Effect of Sodium Benzoate on Siderophore Production by a Potential Isolate

    Directory of Open Access Journals (Sweden)

    Teja Gaonkar

    2012-01-01

    Full Text Available Bioremediation in natural ecosystems is dependent upon the availability of micronutrients and cofactors, of which iron is one of the essential elements. Under aerobic and alkaline conditions, iron oxidizes to Fe+3 creating iron deficiency. To acquire this essential growth-limiting nutrient, bacteria produce low-molecular-weight, high-affinity iron chelators termed siderophores. In this study, siderophore-producing bacteria from rhizosphere and nonrhizosphere areas of coastal sand dunes were isolated using a culture-dependent approach and were assigned to 8 different genera with the predominance of Bacillus sp. Studies on the ability of these isolates to grow on sodium benzoate revealed that a pigmented bacterial culture TMR2.13 identified as Pseudomonas aeruginosa showed growth on mineral salts medium (MSM with 2% of sodium benzoate and produced a yellowish fluorescent siderophore identified as pyoverdine. This was inhibited above 54 μM of added iron in MSM with glucose without affecting growth, while, in presence of sodium benzoate, siderophore was produced even up to the presence of 108 μM of added iron. Increase in the requirement of iron for metabolism of aromatic compounds in ecosystems where the nutrient deficiencies occur naturally would be one of the regulating factors for the bioremediation process.

  16. Siderophore-producing bacteria from a sand dune ecosystem and the effect of sodium benzoate on siderophore production by a potential isolate.

    Science.gov (United States)

    Gaonkar, Teja; Nayak, Pramoda Kumar; Garg, Sandeep; Bhosle, Saroj

    2012-01-01

    Bioremediation in natural ecosystems is dependent upon the availability of micronutrients and cofactors, of which iron is one of the essential elements. Under aerobic and alkaline conditions, iron oxidizes to Fe(+3) creating iron deficiency. To acquire this essential growth-limiting nutrient, bacteria produce low-molecular-weight, high-affinity iron chelators termed siderophores. In this study, siderophore-producing bacteria from rhizosphere and nonrhizosphere areas of coastal sand dunes were isolated using a culture-dependent approach and were assigned to 8 different genera with the predominance of Bacillus sp. Studies on the ability of these isolates to grow on sodium benzoate revealed that a pigmented bacterial culture TMR2.13 identified as Pseudomonas aeruginosa showed growth on mineral salts medium (MSM) with 2% of sodium benzoate and produced a yellowish fluorescent siderophore identified as pyoverdine. This was inhibited above 54 μM of added iron in MSM with glucose without affecting growth, while, in presence of sodium benzoate, siderophore was produced even up to the presence of 108 μM of added iron. Increase in the requirement of iron for metabolism of aromatic compounds in ecosystems where the nutrient deficiencies occur naturally would be one of the regulating factors for the bioremediation process.

  17. Biofilm-associated indole acetic acid producing bacteria and their impact in the proliferation of biofilm mats in solar salterns

    Digital Repository Service at National Institute of Oceanography (India)

    Kerkar, S.; Raiker, L.; Tiwari, A.; Mayilraj, S.; Dastager, S.

    (peptone 5 g., NaCl 5 g., beef extract 1.5 g., yeast extract 1.5 g., prepared in salt pan water 1 L, agar 2 %, pH 7.4 ± 0.2) and incubated overnight at room temperature (28±2°C). Morphologically different colonies were isolated, purified and stored... spectrophotometrically as mentioned above. Effect of tryptophan on IAA production Bacteria (initial counts were 10 3 cells/mL estimated using a haemocytometer) were grown separately in 10 % ZMB broth (25 mL) prepared in salt pan water in 100mL flasks (in triplicates...

  18. Control of Cultivable IAA-Producing Bacteria by the Plant Arabidopsis thaliana and the Earthworm Aporrectodea caliginosa

    Directory of Open Access Journals (Sweden)

    Ruben Puga-Freitas

    2012-01-01

    Full Text Available Some soil microorganisms are involved in the complex interactions with plants and earthworms, through the production of indole acetic acid (IAA which modifies plant growth and development. In a factorial experiment testing the impact of the presence/absence of plants and earthworms on IAA production by cultivable bacteria, we observed that plants were decreasing IAA production of 43%, whereas earthworms were increasing it of 46%. In the presence of both plant and earthworms, IAA production was as low as in the presence of plant control, showing that plants influence on IAA production by microorganisms prevails on earthworm influence. We discuss functional reasons which could explain this result.

  19. Analysis of dominant lactic acid bacteria from artisanal raw milk cheeses produced on the mountain Stara Planina, Serbia

    Directory of Open Access Journals (Sweden)

    Begovic Jelena

    2011-01-01

    Full Text Available Traditional Serbian cheese production has a long history and generates products with rich flavor profiles. To enable the industrial manufacture of these home-made Serbian cheeses, the lactic acid bacteria present in them needs to be characterized. Five fresh white cheeses made from raw cow’s milk without commercial starter cultures were collected from households on the mountain Stara Planina, Serbia. According to phenotypical and molecular analysis, 262 isolated Lwere found to belong to Lactococcus, Lactobacillus, Streptococcus, Leuconostoc or Enterococcus. The unique bacterial composition of each cheese indicates that the preservation of household industry is the way to maintain production of distinct cheeses.

  20. Nondairy beverage produced by controlled fermentation with potential probiotic starter cultures of lactic acid bacteria and yeast.

    Science.gov (United States)

    Freire, Ana Luiza; Ramos, Cintia Lacerda; da Costa Souza, Patrícia Nirlane; Cardoso, Mauro Guilherme Barros; Schwan, Rosane Freitas

    2017-02-21

    This work aimed to develop a nondairy fermented beverage from a blend of cassava and rice based on Brazilian indigenous beverage cauim using probiotic lactic acid bacteria (LAB) and yeast. The indigenous strains Lactobacillus plantarum CCMA 0743 (from cauim) and Torulaspora delbrueckii CCMA 0235 (from tarubá), and the commercial probiotic, L. acidophilus LAC-04, were used as starter cultures in single and co-cultivations. The bacteria populations were around 8.0 log (CFU/mL) at the end of all fermentations as recommended for probiotic products. Higher residual starch contents were noted in the single LAB cultures (10.6% [w/w]) than in co-cultures (1.6g/L) and ethanol was lower than 0.5% (w/v) consisting in a non-alcoholic beverage. The assays containing yeast showed the highest antioxidant activity (around 10% by DPPH and ABTS methods). Therefore, a nondairy fermented beverage was successfully obtained, and the co-culture of LAB and T. delbrueckii could increase the product's functional properties.

  1. Application of modified-alginate encapsulated carbonate producing bacteria in concrete: a promising strategy for crack self-healing

    Directory of Open Access Journals (Sweden)

    Jianyun eWang

    2015-10-01

    Full Text Available Self-healing concrete holds promising benefits to reduce the cost for concrete maintenance and repair as cracks are autonomously repaired without any human intervention. In this study, the application of a carbonate precipitating bacterium Bacillus sphaericus was explored. Regarding the harsh condition in concrete, B. sphaericus spores were first encapsulated into a modified-alginate based hydrogel (AM-H which was proven to have a good compatibility with the bacteria and concrete regarding the influence on bacterial viability and concrete strength. Experimental results show that the spores were still viable after encapsulation. Encapsulated spores can precipitate a large amount of CaCO3 in/on the hydrogel matrix (around 70% by weight. Encapsulated B. sphaericus spores were added into mortar specimens and bacterial in-situ activity was demonstrated by the oxygen consumption on the mimicked crack surface. Specimens with free spores added showed no oxygen consumption. This indicates the efficient protection of the hydrogel for spores in concrete. To conclude, the AM-H encapsulated carbonate precipitating bacteria have great potential to be used for crack self-healing in concrete applications.

  2. Application of modified-alginate encapsulated carbonate producing bacteria in concrete: a promising strategy for crack self-healing.

    Science.gov (United States)

    Wang, Jianyun; Mignon, Arn; Snoeck, Didier; Wiktor, Virginie; Van Vliergerghe, Sandra; Boon, Nico; De Belie, Nele

    2015-01-01

    Self-healing concrete holds promising benefits to reduce the cost for concrete maintenance and repair as cracks are autonomously repaired without any human intervention. In this study, the application of a carbonate precipitating bacterium Bacillus sphaericus was explored. Regarding the harsh condition in concrete, B. sphaericus spores were first encapsulated into a modified-alginate based hydrogel (AM-H) which was proven to have a good compatibility with the bacteria and concrete regarding the influence on bacterial viability and concrete strength. Experimental results show that the spores were still viable after encapsulation. Encapsulated spores can precipitate a large amount of CaCO3 in/on the hydrogel matrix (around 70% by weight). Encapsulated B. sphaericus spores were added into mortar specimens and bacterial in situ activity was demonstrated by the oxygen consumption on the mimicked crack surface. While specimens with free spores added showed no oxygen consumption. This indicates the efficient protection of the hydrogel for spores in concrete. To conclude, the AM-H encapsulated carbonate precipitating bacteria have great potential to be used for crack self-healing in concrete applications.

  3. Composition of Asarum heterotropoides var. mandshuricum radix oil from different extraction methods and activities against human body odor-producing bacteria

    Directory of Open Access Journals (Sweden)

    A.S.M. Tanbirul Haque

    2016-10-01

    Full Text Available In this study, oils from Asarum heterotropoides were extracted by traditional solvent extraction and supercritical CO2 (SC-CO2 extraction methods and their antioxidant activities along with antimicrobial and inhibitory activities against five human body odor-producing bacteria (Staphylococcus epidermidis, Propionibacterium freudenreichii, Micrococcus luteus, Corynebacterium jeikeium, and Corynebacterium xerosis were evaluated. The oil was found to contain 15 components, among which the most abundant component was methyl eugenol (37.6%, which was identified at every condition studied in different extraction methods. The oil extracted with n-hexane and ethanol mixture exhibited a strong antioxidant activity (92% ± 2% and the highest ABTS and 2,2-diphenyl-1-picrylhydrazyl scavenging activities (89% ± 0.2%. The highest amounts of total phenolic content and total flavonoid content were 23.1±0.4 mg/g and 4.9±0.1 mg/g, respectively, in the traditional method. In the SC-CO2 method performed at 200 bar/50°C using ethanol as an entrainer, the highest inhibition zone was recorded against all the aforementioned bacteria. In particular, strong antibacterial activity (38±2 mm was found against M. luteus. The minimum inhibitory concentration (MIC for the oil against bacteria ranged from 10.1±0.1 μg/mL to 46±2 μg/mL. The lowest MIC was found against M. luteus. Methyl eugenol was found to be one of the major compounds working against human body odor-producing bacteria.

  4. H2− formation in electron impact ionization of H2 near threshold

    NARCIS (Netherlands)

    Boesten, L.G.J.; Heideman, H.G.M.; Schowengerdt, F.D.; Golden, D.E.; Ormonde, S.

    1974-01-01

    New features in near threshold ionization spectra of H2 which can be correlated with two series of H2− states proceeding across the H2+ threshold, indicate a need for coincidence experiments that differentiate between one and two electron decay modes of H2−.

  5. H2− formation in electron impact ionization of H2 near threshold

    NARCIS (Netherlands)

    Boesten, L.G.J.; Heideman, H.G.M.; Schowengerdt, F.D.; Golden, D.E.; Ormonde, S.

    1974-01-01

    New features in near threshold ionization spectra of H2 which can be correlated with two series of H2− states proceeding across the H2+ threshold, indicate a need for coincidence experiments that differentiate between one and two electron decay modes of H2−.

  6. Photolysis of H2O-H2O2 Mixtures: The Destruction of H2O2

    Science.gov (United States)

    Loeffler, M. J.; Fama, M.; Baragiola, R. A.; Carlson, R. W.

    2013-01-01

    We present laboratory results on the loss of H2O2 in solid H2O + H2O2 mixtures at temperatures between 21 and 145 K initiated by UV photolysis (193 nm). Using infrared spectroscopy and microbalance gravimetry, we measured the decrease of the 3.5 micrometer infrared absorption band during UV irradiation and obtained a photodestruction cross section that varies with temperature, being lowest at 70 K. We use our results, along with our previously measured H2O2 production rates via ionizing radiation and ion energy fluxes from the spacecraft to compare H2O2 creation and destruction at icy satellites by ions from their planetary magnetosphere and from solar UV photons. We conclude that, in many cases, H2O2 is not observed on icy satellite surfaces because the H2O2 photodestruction rate is much higher than the production rate via energetic particles, effectively keeping the H2O2 infrared signature at or below the noise level.

  7. In vitro susceptibility of characterized β-lactamase-producing Gram-negative bacteria isolated in Japan to ceftazidime-, ceftaroline-, and aztreonam-avibactam combinations.

    Science.gov (United States)

    Yoshizumi, Ayumi; Ishii, Yoshikazu; Aoki, Kotaro; Testa, Raymond; Nichols, Wright W; Tateda, Kazuhiro

    2015-02-01

    Avibactam displays potent inhibition of extended-spectrum, AmpC, KPC and some OXA β-lactamases. We examined the combinations of avibactam with ceftazidime, ceftaroline and aztreonam by the broth microdilution method against Gram-negative bacteria harboring molecularly-characterized β-lactamase genes collected in Toho University, Japan. Bacterial isolates included: Ambler class A β-lactamase-producing Enterobacteriaceae (n = 26); class C β-lactamase-producing Enterobacteriaceae (n = 9) and class D β-lactamase-producing Acinetobacter baumannii (n = 9) and Enterobacteriaceae (n = 3). Ceftazidime-avibactam, ceftaroline-avibactam ands aztreonam-avibactam were active against the strains with an extended-spectrum β-lactamase (ESBL) or AmpC enzymes, but combination with avibactam did not reduce β-lactam MICs against A. baumannii with OXA β-lactamases including carbapenemases, such as OXA-40 and -69.

  8. The δ15N and δ18O values of N2O produced during the co-oxidation of ammonia by methanotrophic bacteria

    Science.gov (United States)

    Mandernack, Kevin W.; Mills, Christopher T.; Johnson, Craig A.; Rahn, Thomas; Kinney, Chad

    2009-01-01

    In order to determine if the δ15N and δ18O values of N2O produced during co-oxidation of NH4+ by methanotrophic (methane oxidizing) bacteria can be isotopically distinguished from N2O produced either by autotrophic nitrifying or denitrifying bacteria, we conducted laboratory incubation experiments with pure cultures of methanotrophic bacteria that were provided NH4Cl as an oxidation substrate. The N2O produced during NH4+ oxidation by methanotrophic bacteria showed nitrogen isotope fractionation between NH4+ and N2O (εN2O–NH4+) of − 48 and − 55‰ for Methylomonas methanica and Methylosinus trichosporium, OB3b respectively. These large fractionations are similar to those previously measured for autotrophic nitrifying bacteria and consistent with N2O formation by multiple rate limiting steps that include NH4+oxidation by the methane monooxygenase enzyme and reduction of NO2− to N2O. Consequently, N2O formed by NH4+ oxidation via methanotrophic or autotrophic nitrifying bacteria might generally be characterized by lower δ15NN2O values than that formed by denitrificaiton, although this also depends on the variability of δ15N of available nitrogen sources (e.g., NH4+, NO3−, NO2−). Additional incubations with M. trichosporium OB3b at high and low CH4 conditions in waters of different δ18O values revealed that 19–27% of the oxygen in N2O was derived from O2 with the remainder from water. The biochemical mechanisms that could explain this amount of O2 incorporation are discussed. The δ18O of N2O formed under high CH4 conditions was ~ + 15‰ more positive than that formed under lower CH4 conditions. This enrichment resulted in part from the incorporation of O2 into N2O that was enriched in 18O due to an isotope fractionation effect of − 16.1 ± 2.0‰ and − 17.5 ± 5.4‰ associated with O2 consumption during the high and low methane concentration incubations, respectively. Therefore, N2O formed by NH4+

  9. Enteropathogenic bacteria and enterotoxin-producing Staphylococcus aureus isolated from ready-to-eat foods in Khon Kaen, Thailand.

    Science.gov (United States)

    Chomvarin, Chariya; Chantarasuk, Yingrit; Srigulbutr, Sugunya; Chareonsudjai, Sorujsiri; Chaicumpar, Kunyaluk

    2006-09-01

    The objective of this study was to investigate the microbiological quality of ready-to-eat food in the Municipality of Khon Kaen, Thailand. Four categories of 186 food samples were collected: (1) high heat food; (2) low heat food; (3) no heat food; and, 4) on-site prepared fruit juices and beverages. Of the food samples, 145 (78%) failed to meet acceptable microbiological standards, including fruit juice and beverages (100%), no heat food (91.7%), low heat food (81.7%) and high heat food (57.9%). The most frequent bacterial indexes indicating unacceptability were the most probable number (MPN) of coliforms (78%), the bacterial colony count (58%), and the MPN of E. coli (46%). Pathogenic bacteria were found in 6.5% of food samples. Salmonella, Vibrio cholerae non O1 and Aeromonas hydrophila were found in 4.3, 1.6 and 0.5% of the total food samples, respectively. The serovars of Salmonella found in food were S. Derby, S. Give, S. Krefield, S. Paratyphi B, S. Verchow, S. Lexington and S. Senftenberg. Staphylococcus aureus concentrations of >10(2) CFU/g and >10(5) CFU/g were found in 10.8% and 1.1% of the food samples. Enterotoxin types AB and A of S. aureus were found in 2.7% of the food samples. These results indicate that more than half of the ready-to-eat foods tested in Khon Kaen municipality did not meet microbiological national standards and many kinds of enteropathogenic bacteria were found, suggesting food stalls may be a source of foodborne disease.

  10. Length polymorphisms for intergenic spacer regions of 16S-23S rDNA in members of the new hydrogen-producing bacteria

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A method based on PCR amplification of the 16S rRNA gene (rDNA) -23S rDNA intergenic spacer regions (ISR) was developed for the identification of species within the novel group hydrogen-producing anaerobes. The sizes of the PCR products varied from 1264 to 398 bp. Strain of isolate Rennanqilyf 3 was characterized as having products of 1262, 398, 638, 437 and 436 bp. The isolate Rennanqilyf 1 had product of 1264 bp. The isolate Rennanqilyf 13 had products of 1261, 579 and 485 bp. Of the 3 species of the novel group hydrogenproducing anaerobes examined, no one was indistinguishable. Two environmental isolates were identified as hydrogen-producing bacteria, which were new species in present taxon. Rennanqilyf 3 could not be associated With any Clostridium sp. Studied. Rennanqilyf 1 could be classified into Clostridium genus. The combination between 16S rDNA equencing and length polymorphisms of IRS in 16S-23S rDNA is a better method for determining species of the hydrogen-producing bacteria.

  11. NMR Evidence of Cage-to-Cage Diffusion of H2 in H2-Clathrates

    Science.gov (United States)

    Senadheera, Lasitha; Conradi, Mark

    2008-03-01

    H2 and heavy-ice at P>1 kbar and T ˜250 K form H2-D2O clathrate; four and one H2 may occupy each large (L) and small (S) cage, respectively. In H2-THF-H2O clathrate, H2 occupies singly and only S cages. Previous electronic-structure calculations estimate the barriers for H2 passage though hexagonal and pentagonal faces of cages as ˜6 and ˜25 kcal/mol, respectively. Our H2 NMR linewidth data reflect random crystal fields from frozen cage-wall D2O orientations. We find dramatic reductions in linewidth starting at 120 K (175 K) for H2-D2O (H2-TDF-D2O) indicating time-averaging of the crystal fields. Assuming Arrhenius behavior, our data imply energies for escape from L (S) cages of about ˜4 (˜6) kcal/mol. For L cages, the agreement with the calculated (cages were treated as rigid) barrier is reasonable. For H2 in S cages, in H2-TDF-D2O, the extreme disagreement with theory points to another mechanism of time-averaging, reorientations of the cage-wall D2O molecules, as suggested by previous work in TDH-H2O clathrate. Our limited NMR spectra at high T ˜145 K in H2-D2O show evidence of distinct resonances from diffusionally mobile and immobile H2 molecules, as expected.

  12. Profile of antimicrobial susceptibility isolated microorganisms from hospitalized patients in PICU ward and detection of Methicillin-resistant Staphylococcus aureus and ESBL-producing bacteria by phenotypic methods

    Directory of Open Access Journals (Sweden)

    Shahla Abbas Poor

    2014-10-01

    Full Text Available Background: Hospital-acquired infections are a major challenge to patient. A range of gram-negative organisms are responsible for hospital-acquired infections, the Enterobacteriaceae family being the most commonly identified group overall. Infections by ESBL producers are associated with severe adverse clinical outcomes that have led to increased mortality, prolonged hospitalization, and rising medical costs. The aim of this study was to survey profile of antimicrobial susceptibility isolated microorganisms from hospitalized patients in PICU ward and detection of methicillin-resistant Staphylococcus aureus and ESBL-producing bacteria by phenotypic methods. Material and Methods: In this study participants were patients hospitalized in PICU part of Bahrami Hospital, Tehran, with attention to involved organ. For isolation of bacteria from patient’s samples, culture performed on different selective and differential media. After confirmation of bacteria by biochemical tests, susceptibility testing was performed by disc diffusion method. Phenotypic detection of MRSA strains was performed using cefoxcitin disc. ESBL producing strains were detected by ceftazidime (CAZ and ceftazidime/clavulanic acid (CAZ/CLA discs. Results: Among all isolated organisms from clinical samples, the most common isolated organisms were Escherichia coli (24 cases, Pseudomonas areoginosa (9 cases and Staphylococcus aureus (8 cases, respectively. Among eight MRSA isolated strains from different clinical samples, six strains (75% were MRSA. Among 52 isolated gram negative organisms, 5 strains (9/6% were ESBL. Conclusion: Standard interventions to prevent the transmission of antimicrobial resistance in health care facilities include hand hygiene, using barrier precautions in the care of colonized and infected patients, using dedicated instruments and equipment for these patients. The colonized or infected patients should be isolated in single rooms, multibed rooms or areas

  13. Isolation of a bacteriocin-producing lactococcus lactis and application of its bacteriocin to manage spoilage bacteria in high-value marine fish under different storage temperatures.

    Science.gov (United States)

    Sarika, A R; Lipton, A P; Aishwarya, M S; Dhivya, R S

    2012-07-01

    The bacteriocins of lactic acid bacteria have considerable potential for biopreservation. The Lactococcus lactis strain PSY2 (GenBank account no. JF703669) isolated from the surface of marine perch Perca flavescens produced antibacterial activity against pathogenic and spoilage-causing Gram-positive and Gram-negative bacteria viz. Arthrobacter sp., Acinetobacter sp., Bacillus subtilis, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa and Staphylococcus aureus and possessed broad inhibitory spectrum. The biopreservative efficacy of the bacteriocin PSY2 was evaluated using fillets of reef cod, Epinephelus diacanthus. The fillets (10 g) were sprayed with 2.0 ml of 1,600 AU/ml bacteriocin, wrapped and kept under different storage temperatures viz., 4, 0 and -18 °C. The biopreservative extended the shelf-life of fillets stored at 4 °C to >21 days as against bacteriocin-treated samples stored for 21 days at 4 °C while the untreated samples became unacceptable by the 14th day. The biopreservative gave no significant effect at -18 °C. Thus, the bacteriocin derived from L. lactis PSY2 gave increased protection against spoilage bacteria and offers an alternative for the preservation of high-value sea foods.

  14. Leaf-associated bacteria from transgenic white poplar producing resveratrol-like compounds: isolation, molecular characterization, and evaluation of oxidative stress tolerance.

    Science.gov (United States)

    Balestrazzi, Alma; Bonadei, Martina; Calvio, Cinzia; Mattivi, Fulvio; Carbonera, Daniela

    2009-07-01

    The aim of this study was the isolation and characterization of the culturable bacteria inhabiting the leaves of transgenic white poplars (Populus alba L. 'Villafranca') engineered with the StSy gene for the production of resveratrol-like compounds. Resveratrol glucosides are available in small amounts from natural sources or by expensive chemical synthesis procedures. An alternative approach for the large-scale production of these relevant pharmaceuticals is the use of transgenic plants as bioreactors, although the occurrence of novel molecules in plants growing under field conditions might interfere, to some extent, with the associated microbial population. Both epiphytes and endophytes were isolated from the leaves of 2 StSy transgenic lines producing resveratrol glucosides and from an untransformed plant line grown in a greenhouse. Eleven isolates were recovered and classified as members of the genus Bacillus by 16S rDNA-based analysis. In addition, 2 isolates were classified as members of the Curtobacterium and Kocuria genera, respectively. Tolerance to hydrogen peroxide, UV-C, and paraquat was evaluated, as were the swimming and swarming motility of the leaf-associated bacteria. Interestingly, the isolates recovered from transgenic tissues showed the ability to withstand oxidative stress compared with isolates recovered from the untransformed poplar line. In vitro bioassays showed that trans-resveratrol inhibited both the swarming and swimming motilities in all the tested bacteria. The effects of trans-resveratrol on flagellin production, required for motility, were also investigated by immunoblot analysis.

  15. Antibacterial activity of Valeriana jatamansi against extended-spectrum β-lactamase producing Gramnegative bacteria causing urinary tract infections

    Directory of Open Access Journals (Sweden)

    Babar Habib

    2016-10-01

    Full Text Available Objective: To find out the antibacterial activity of Valeriana jatamansi (V. jatamansi rhizomes against the extended-spectrum β-lactamases (ESBLs producing isolates of Enterobacteriaceae family. Methods: Confirmation of ESBLs producing Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae and Hafnia alvei isolated from urinary tract infections was performed by double disc diffusion assay. Antimicrobial susceptibility of all ESBLs producing isolates was determined by disc diffusion method following guidelines of Clinical and Laboratory Standards Institute. Successive extraction of rhizomes of V. jatamansi was performed with hexane, chloroform and methanol using Soxhelt apparatus. These extracts were tested against the ESBLs producing isolates using well diffusion method. Results: Hexane extract showed significant results as compared to chloroform and methanol extracts with the maximum zone of inhibition (21 mm while ciprofloxacin and amikacin were used as standard drugs. Conclusions: Findings of the study suggested that hexane extract of V. jatamansi can be used in combination with other antibiotics as alternative treatment for urinary tract infections caused by ESBLs producing strains of Enterobacteriaceae.

  16. Robust H2 estimation and control

    Institute of Scientific and Technical Information of China (English)

    Lihua XIE; Yeng Chai SOH; Chunling DU; Yun ZOU

    2004-01-01

    This paper is concerned with the H2 estimation and control problems for uncertain discretetime systems with norm-bounded parameter uncertainty. We first present an analysis result on H2 norm bound for a stable uncertain system in terms of linearmatrix inequalities (LMIs). A solution to the robust H2 estimation problem is then derived in terms of two LMIs. As compared tothe existing results, our result on robust H2 estimation is more general. In addition, explicit search of appropriate scaling parametersis not needed as the optimization is convex in the scaling parameters. The LMI approach is also extended to solve the robust H2control problem which has been difficult for the traditional Riccati equation approach since no separation principle has been knownfor uncertain systems. The design approach is demonstrated through a simple example.

  17. Growth of Brassica juncea under chromium stress: influence of siderophores and indole 3 acetic acid producing rhizosphere bacteria.

    Science.gov (United States)

    Rajkumar, M; Lee, Kui Jae; Lee, Wang Hyu; Banu, J Rajesh

    2005-10-01

    Plant growth promoting rhizobacterial (PGPR) strains A3 and S32 have been shown to promote the growth of Brassica juncea under chromium stress which has been related to the microbial production of siderophores and indole 3 acetic acid (IAA). The aim of the present study is to evaluate the importance of siderophores and IAA producing PGPR on the growth of Brassica juncea under chromium stress. The production of IAA and siderophores were observed in the strains A3 and S32, respectively. Both PGPR strains promote the growth of Brassica juncea under chromium stress. The maximum growth was observed in plants inoculated with siderophores producing strain 32. Both the bacterial inoculum did not influence the uptake of chromium by plants. The present observation showed that PGPR isolates A3 and S32 are capable of protecting the plants against the inhibitory effects of chromium by producing the siderophores and IAA.

  18. Quantification of Growth of Campylobacter and Extended Spectrum β-Lactamase Producing Bacteria Sheds Light on Black Box of Enrichment Procedures

    Directory of Open Access Journals (Sweden)

    Wilma Carolina Hazeleger

    2016-09-01

    Full Text Available Campylobacter is well recognized as the leading cause of bacterial foodborne diarrheal disease worldwide, and is routinely found in meat originating from poultry, sheep, pigs, and cattle. Effective monitoring of Campylobacter contamination is dependent on the availability of reliable detection methods. The method of the International Organization for Standardization for the detection of Campylobacter spp. in food (ISO 10272-1:2006 recommends the use of Bolton broth as selective enrichment medium, including a pre-enrichment step of 4-6 h at 37°C to revive sublethally damaged cells prior to incubation for two days at 41.5°C. Recently the presence of abundantly growing extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL bacteria has become one of the most important factors that interfere with the isolation of Campylobacter, resulting in false-negative detection. However, detailed growth dynamics of Campylobacter and its competitors remain unclear, where these would provide a solid base for further improvement of the enrichment procedure for Campylobacter. Other enrichment broths, such as Preston broth and Bolton broth plus clavulanic acid have been suggested to inhibit competitive flora. Therefore these different broths were used as enrichments to measure the growth kinetics of several strains of C. jejuni and ESBL bacteria separately, in co-culture and of strains in chicken samples.The maximum cell numbers and often the growth rates of Campylobacter in mixed culture with ESBL bacteria were significantly lower than in single cultures, indicating severe suppression of Campylobacter by ESBL bacteria, also in naturally contaminated samples. Preston broth and Bolton broth plus clavulanic acid successfully diminished ESBL bacteria and might therefore be a better choice as enrichment medium in possibly ESBL-bacteria contaminated samples. The efficacy of a pre-enrichment step in the Bolton broth ISO-procedure was not supported for cold

  19. Quantification of Growth of Campylobacter and Extended Spectrum β-Lactamase Producing Bacteria Sheds Light on Black Box of Enrichment Procedures

    Science.gov (United States)

    Hazeleger, Wilma C.; Jacobs-Reitsma, Wilma F.; den Besten, Heidy M. W.

    2016-01-01

    Campylobacter is well recognized as the leading cause of bacterial foodborne diarrheal disease worldwide, and is routinely found in meat originating from poultry, sheep, pigs, and cattle. Effective monitoring of Campylobacter contamination is dependent on the availability of reliable detection methods. The method of the International Organization for Standardization for the detection of Campylobacter spp. in food (ISO 10272-1:2006) recommends the use of Bolton broth (BB) as selective enrichment medium, including a pre-enrichment step of 4–6 h at 37°C to revive sublethally damaged cells prior to incubation for 2 days at 41.5°C. Recently the presence of abundantly growing extended spectrum β-lactamase producing Enterobacteriaceae (ESBL bacteria) has become one of the most important factors that interfere with the isolation of Campylobacter, resulting in false-negative detection. However, detailed growth dynamics of Campylobacter and its competitors remain unclear, where these would provide a solid base for further improvement of the enrichment procedure for Campylobacter. Other enrichment broths, such as Preston broth (PB) and BB plus clavulanic acid (BBc) have been suggested to inhibit competitive flora. Therefore, these different broths were used as enrichments to measure the growth kinetics of several strains of Campylobacter jejuni and ESBL bacteria separately, in co-culture and of strains in chicken samples. The maximum cell numbers and often the growth rates of Campylobacter in mixed culture with ESBL bacteria were significantly lower than in single cultures, indicating severe suppression of Campylobacter by ESBL bacteria, also in naturally contaminated samples. PB and BBc successfully diminished ESBL bacteria and might therefore be a better choice as enrichment medium in possibly ESBL-bacteria contaminated samples. The efficacy of a pre-enrichment step in the BB ISO-procedure was not supported for cold-stressed and non-stressed cells. Therefore, omission

  20. Transport of H2S and HS− across the human red blood cell membrane: rapid H2S diffusion and AE1-mediated Cl−/HS− exchange

    Science.gov (United States)

    2013-01-01

    The rates of H2S and HS− transport across the human erythrocyte membrane were estimated by measuring rates of dissipation of pH gradients in media containing 250 μM H2S/HS−. Net acid efflux is caused by H2S/HS− acting analogously to CO2/HCO3− in the Jacobs-Stewart cycle. The steps are as follows: 1) H2S efflux through the lipid bilayer and/or a gas channel, 2) extracellular H2S deprotonation, 3) HS− influx in exchange for Cl−, catalyzed by the anion exchange protein AE1, and 4) intracellular HS− protonation. Net acid transport by the Cl−/HS−/H2S cycle is more efficient than by the Cl−/HCO3−/CO2 cycle because of the rapid H2S-HS− interconversion in cells and medium. The rates of acid transport were analyzed by solving the mass flow equations for the cycle to produce estimates of the HS− and H2S transport rates. The data indicate that HS− is a very good substrate for AE1; the Cl−/HS− exchange rate is about one-third as rapid as Cl−/HCO3− exchange. The H2S permeability coefficient must also be high (>10−2 cm/s, half time H2S and HS− enter erythrocytes very rapidly in the microcirculation of H2S-producing tissues, thereby acting as a sink for H2S and lowering the local extracellular concentration, and the fact that HS− is a substrate for a Cl−/HCO3− exchanger indicates that some effects of exogenous H2S/HS− may not result from a regulatory role of H2S but, rather, from net acid flux by H2S and HS− transport in a Jacobs-Stewart cycle. PMID:23864610

  1. Duration of Colonization With Klebsiella pneumoniae Carbapenemase-Producing Bacteria at Long-Term Acute Care Hospitals in Chicago, Illinois

    NARCIS (Netherlands)

    Haverkate, Manon R; Weiner, Shayna; Lolans, Karen; Moore, Nicholas M; Weinstein, Robert A; Bonten, Marc J M; Hayden, Mary K; Bootsma, Martin C J|info:eu-repo/dai/nl/304830305

    2016-01-01

    Background.  High prevalence of Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae has been reported in long-term acute care hospitals (LTACHs), in part because of frequent readmissions of colonized patients. Knowledge of the duration of colonization with KPC is essential to iden

  2. Selective inhibition of Erwinia amylovora by the herbicidally-active Germination-Arrest Factor (GAF) produced by Pseudomonas bacteria

    Science.gov (United States)

    Aims: The Germination-Arrest Factor (GAF) produced by Pseudomonas fluorescens WH6, and identified as 4-formylaminooxyvinylglycine, specifically inhibits the germination of a wide range of grassy weeds. The present study was undertaken to determine if GAF has antimicrobial activity in addition to it...

  3. Duration of Colonization With Klebsiella pneumoniae Carbapenemase-Producing Bacteria at Long-Term Acute Care Hospitals in Chicago, Illinois

    NARCIS (Netherlands)

    Haverkate, Manon R; Weiner, Shayna; Lolans, Karen; Moore, Nicholas M; Weinstein, Robert A; Bonten, Marc J M; Hayden, Mary K; Bootsma, Martin C J

    2016-01-01

    Background.  High prevalence of Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae has been reported in long-term acute care hospitals (LTACHs), in part because of frequent readmissions of colonized patients. Knowledge of the duration of colonization with KPC is essential to iden

  4. [Cooperation of mixed culturing bacteria in the hydrogen production by fermentation].

    Science.gov (United States)

    Lin, Ming; Ren, Nanqi; Wang, Aijie; Wang, Xiangjing

    2003-03-01

    In order to discuss the cooperation of H2-producing fermentation bacteria (HPFB) in mixed culture, a batch test fed with glucose and complex organic substance (starch, beef, PEP and peptone) respectively, was conducted to investigate the effects of mixed culture on H2-producing ability. For the systemic and accurate analysis, three kinds of the mixed culture were use to this batch test. It included that the mixed culture with five strains of HPFB (B49, H1, LM12, LM11 and B51), B49 and three stains of non-HPFB (L10, Bacteroide 3-2, Sporobacterl), and B49 and hydrogen producing sludge. The results showed that the cooperation of mixed culturing bacteria was conditional on the substrates. When fed with glucose, which were easily utilized by HPB, the H2-producing ability of HPB was restrained because of the competition on the co-substrate between HPB and other fermentation bacteria, and it was quite difficult for the cooperation of mixed culturing bacteria to be performed. When fed with complex organic substance, the H2-producing ability of HPB was enhanced via the cooperation of mixed culturing bacteria. Furthermore, a strategy was put forward, that is, different kind of HPB cultures could be adopted according to the difference of substrates.

  5. Screening for anti-listerial bacteriocin-producing lactic acid bacteria from "Gueddid" a traditionally Tunisian fermented meat.

    Science.gov (United States)

    Ben Belgacem, Zouhaier; Ferchichi, Mounir; Prévost, Hervé; Dousset, Xavier; Manai, Mohamed

    2008-04-01

    Forty eight lactic acid bacteria strains isolated from "Gueddid", a traditionally Tunisian fermented meat, were screened for bacteriocin production. Four strains named MMZ 04, 09, 13, and 17 showed antimicrobial activity and were identified as Enterococcus faecium by molecular methods based on the 16S-23S rDNA ISR, PCR-RFLP analysis of the 16S-23S rDNA ISR and species-specific primers. The four antimicrobial compounds were heat stable (121°C for 15min), active over a wide pH range (3-9) and the antimicrobial activity was lost after treatment with trypsin, α-chymotrypsin and proteinase K but not by lysozyme and lipase. The mode of action of enterocin MMZ17 was identified as bactericidal. The MMZ17 bacteriocin was partially purified by ammonium sulphate precipitation and C(18) Sep-Pack chromatography. The apparent molecular size of enterocin MMZ17 as indicated by activity detection after SDS-PAGE was lower than 6.5 KDa. According to these assays, enterocin MMZ17 can be classified as a small, heat-stable Listeria-active peptide, presumably belonging to class IIa bacteriocins.

  6. Relationship of Enhanced Butyrate Production by Colonic Butyrate-Producing Bacteria to Immunomodulatory Effects in Normal Mice Fed an Insoluble Fraction of Brassica rapa L.

    Science.gov (United States)

    Tanaka, Sachi; Yamamoto, Kana; Yamada, Kazuki; Furuya, Kanon; Uyeno, Yutaka

    2016-05-01

    This study was performed to determine the effects of feeding a fiber-rich fraction of Brassica vegetables on the immune response through changes in enteric bacteria and short-chain fatty acid (SCFA) production in normal mice. The boiled-water-insoluble fraction of Brassica rapa L. (nozawana), which consists mainly of dietary fiber, was chosen as a test material. A total of 31 male C57BL/6J mice were divided into two groups and housed in a specific-pathogen-free facility. The animals were fed either a control diet or the control diet plus the insoluble B. rapa L. fraction for 2 weeks and sacrificed to determine microbiological and SCFA profiles in lower-gut samples and immunological molecules. rRNA-based quantification indicated that the relative population of Bacteroidetes was markedly lower in the colon samples of the insoluble B. rapa L. fraction-fed group than that in the controls. Populations of the Eubacterium rectale group and Faecalibacterium prausnitzii, both of which are representative butyrate-producing bacteria, doubled after 2 weeks of fraction intake, accompanying a marginal increase in the proportion of colonic butyrate. In addition, feeding with the fraction significantly increased levels of the anti-inflammatory cytokine interleukin-10 (IL-10) and tended to increase splenic regulatory T cell numbers but significantly reduced the population of cells expressing activation markers. We demonstrated that inclusion of the boiled-water-insoluble fraction of B. rapa L. can alter the composition of the gut microbiota to decrease the numbers of Bacteroidetes and to increase the numbers of butyrate-producing bacteria, either of which may be involved in the observed shift in the production of splenic IL-10. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  7. Presence of acylated homoserine lactones (AHLs) and AHL-producing bacteria in meat and potential role of AHL in spoilage of meat.

    Science.gov (United States)

    Bruhn, Jesper Bartholin; Christensen, Allan Beck; Flodgaard, Lars Ravn; Nielsen, Kristian Fog; Larsen, Thomas Ostenfeld; Givskov, Michael; Gram, Lone

    2004-07-01

    Quorum-sensing (QS) signals (N-acyl homoserine lactones [AHLs]) were extracted and detected from five commercially produced vacuum-packed meat samples. Ninety-six AHL-producing bacteria were isolated, and 92 were identified as Enterobacteriaceae. Hafnia alvei was the most commonly identified AHL-producing bacterium. Thin-layer chromatographic profiles of supernatants from six H. alvei isolates and of extracts from spoiling meat revealed that the major AHL species had an R(f) value and shape similar to N-3-oxo-hexanoyl homoserine lactone (OHHL). Liquid chromatography-mass spectrometry (MS) (high-resolution MS) analysis confirmed the presence of OHHL in pure cultures of H. alvei. Vacuum-packed meat spoiled at the same rate when inoculated with the H. alvei wild type compared to a corresponding AHL-lacking mutant. Addition of specific QS inhibitors to the AHL-producing H. alvei inoculated in meat or to naturally contaminated meat did not influence the spoilage of vacuum-packed meat. An extracellular protein of approximately 20 kDa produced by the H. alvei wild-type was not produced by the AHL-negative mutant but was restored in the mutant when complemented by OHHL, thus indicating that AHLs do have a regulatory role in H. alvei. Coinoculation of H. alvei wild-type with an AHL-deficient Serratia proteamaculans B5a, in which protease secretion is QS regulated, caused spoilage of liquid milk. By contrast, coinoculation of AHL-negative strains of H. alvei and S. proteamaculans B5a did not cause spoilage. In conclusion, AHL and AHL-producing bacteria are present in vacuum-packed meat during storage and spoilage, but AHL does not appear to influence the spoilage of this particular type of conserved meat. Our data indicate that AHL-producing H. alvei may induce food quality-relevant phenotypes in other bacterial species in the same environment. H. alvei may thus influence spoilage of food products in which Enterobacteriaceae participate in the spoilage process.

  8. Quantification of total and specific gram-negative histamine-producing bacteria species in fish using an MPN real-time PCR method.

    Science.gov (United States)

    Bjornsdottir-Butler, Kristin; Jones, Jessica L; Benner, Ronald A; Burkhardt, William

    2011-10-01

    Quantification of histamine-producing bacteria (HPB) is necessary in order to elucidate the role that HPB play in scombrotoxin (histamine) fish poisoning. We report here the evaluation of a real-time PCR method for the quantification of total and specific Gram-negative HPB species in fish using a most probable number (MPN) format. The species-specific real-time PCR assay was 100% inclusive for independently detecting Morganella morganii, Enterobacter aerogenes, Raoultella planticola/ornithinolytica and Photobacterium damselae and did not cross react with other histamine- or non- histamine-producing bacteria. The efficiency of the reactions in the absence and presence of Spanish mackerel enrichment containing 1 × 10(6) CFU/ml of background microflora were 93-104 and 92-99%, respectively. The MPN-real-time PCR assay accurately quantified total and specific HPB in spiked mahi-mahi (Coryphaena hippurus) and Spanish mackerel (Scomberomorus maculates) samples. These methods were used to quantify total and specific HPB in naturally contaminated, decomposing mahi-mahi, Spanish mackerel and tuna (Thunnus albacares) samples. The results of this study indicate that MPN-real-time PCR assays can be used to accurately enumerate total and specific HPB in fish samples. These assays can be applied to assess the effectiveness of mitigation strategies and understand the relationship between HPB and histamine production in decomposing fish.

  9. Off-odor compounds produced in cork by isolated bacteria and fungi: a gas chromatography-mass spectrometry and gas chromatography-olfactometry study.

    Science.gov (United States)

    Prat, Chantal; Trias, Rosalia; Culleré, Laura; Escudero, Ana; Anticó, Enriqueta; Bañeras, Lluís

    2009-08-26

    The risk of development of specific olfactory profiles in cork was evaluated after inoculation of cork granules and agglomerated and natural cork stoppers with isolated bacteria and fungi. The highest incidence of off-odor development was found in assays when fungi were inoculated. Cork granules with musty-earthy, musty-earthy-TCA, and vegetative deviations were inspected by gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). Sixteen odor zones were clearly recognized in the GC-O analyses. Among these, octanal, 2-methoxy-3,5-dimethylpyrazine (MDMP), Z-2-nonenal, 2-methylisoborneol, 2,4,6-trichloroanisole (TCA), geosmin, and guaiacol were the most significant odorants and helped in the discrimination of sensory deviations. Only TCA and guaiacol were detected above their respective detection limits by HS-SPME-GC-MS. The fungi Cryptococcus sp. isolate F020, Rhodotorula sp. isolate F025, Penicillium glabrum isolate F001, and Pennicillium variabile F003A and the bacterium Pseudomonas jessenii isolate A1 were found to produce TCA to a greater extent. Additionally, 13 of 38 isolated microorganisms (2 bacteria and 11 fungi) proved able to produce unpleasant musty-earthy or vegetative odors that were not related to a significant TCA accumulation.

  10. [EFFECT OF MICROSYMBIONTS ON THE ABILITY OF VAGINAL EPITHELIOCYTES TO MODIFY BIOLOGICAL PROPERTIES OF BACTERIA].

    Science.gov (United States)

    Kremleva, E A; Sgibnev, A V; Cherkasov, S V

    2015-01-01

    Study regularities of effects of various types of vaginal microsymbionts on the ability of mucosal epitheliocytes of the vagina to modify biological properties of bacteria. Effect of thermo-inactivated cells of Staphylococcus aureus, Escherichia coli, H2O2-producing and H2O2-non-producing lactobacilli on the ability of primary vaginal epitheliocytes to alter growth and antagonistic activity of Staphylococcus aureus, Escherichia colt, H2O2-producing and H2O2-nonproducing lactobacilli was studied using a multi-component module system. Alterations of composition of vaginal epitlieliocyte exometabolites under the effect of S. aureus and E. coli was established to result in a pronounced stimulation of antagonistic activity of H2O2-producing and an increase of the number of H2O2-nonproducing lactobacilli. Thermo-inactivated cells of lactobacilli stimulated production of metabolites by epitheliocytes, that suppress the growth and antagonistic activity of allochthonous microflora and stimulate similar parameters of lactobacilli. The strongest effects on the ability of vaginal epitheliocytes to alter biological properties of bacteria were rendered by H2O2-producing lactobacilli. The regularities identified allow to examine epitheliocytes and normoflora of vagina as a symbiotic system, the coordinated interaction of its components is directed on maintaining microecological stability of female reproductive tract.

  11. Oxidative degradation of endotoxin by advanced oxidation process (O3/H2O2 & UV/H2O2).

    Science.gov (United States)

    Oh, Byung-Taek; Seo, Young-Suk; Sudhakar, Dega; Choe, Ji-Hyun; Lee, Sang-Myeong; Park, Youn-Jong; Cho, Min

    2014-08-30

    The presence of endotoxin in water environments may pose a serious public health hazard. We investigated the effectiveness of advanced oxidative processes (AOP: O3/H2O2 and UV/H2O2) in the oxidative degradation of endotoxin. In addition, we measured the release of endotoxin from Escherichia coli following typical disinfection methods, such as chlorine, ozone alone and UV, and compared it with the use of AOPs. Finally, we tested the AOP-treated samples in their ability to induce tumor necrosis factor alpha (TNF-α) in mouse peritoneal macrophages. The production of hydroxyl radical in AOPs showed superior ability to degrade endotoxin in buffered solution, as well as water samples from Korean water treatment facilities, with the ozone/H2O2 being more efficient compared to UV/H2O2. In addition, the AOPs proved effective not only in eliminating E. coli in the samples, but also in endotoxin degradation, while the standard disinfection methods lead to the release of endotoxin following the bacteria destruction. Furthermore, in the experiments with macrophages, the AOPs-deactivated endotoxin lead to the smallest induction of TNF-α, which shows the loss of inflammation activity, compared to ozone treatment alone. In conclusion, these results suggest that AOPs offer an effective and mild method for endotoxin degradation in the water systems.

  12. Triazine-based H2S Scavenging

    DEFF Research Database (Denmark)

    Madsen, Henrik Tækker; Vestergaard Jensen, Carina; Søgaard, Erik Gydesen

    2014-01-01

    The authors studied the applicability of a previously suggested model to describe the reaction between 1,3,5-tri-(2-hydroxypropyl)-hexahydro-s-triazine and H2S and thereby predict formation of fouling. To investigate the reaction system, electrospray ionization mass spectrometry was employed...... to analyze the composition of the generated mixture as H2S is bubbled through the scavenger. The results of the study confirm that the suggested model is capable of explaining how the scavenger reacts with H2S, which may be used to explain from where and how the fouling originates, and how a scavenging...

  13. Characterization of nitrogen-fixing bacteria from a temperate saltmarsh lagoon, including isolates that produce ethane from acetylene.

    Science.gov (United States)

    Tibbles, B J; Rawlings, D E

    1994-01-01

    Nitrogen-fixing bacteria were isolated from sediments and water of a saltmarsh lagoon on the west coast of South Africa, and characterized according to factors that regulate nitrogen fixation in the marine environment. The majority of isolates were assigned to the Photobacterium or Vibrio genera on the basis of physiological and biochemical characteristics. One isolate was further assigned to the species Vibrio diazotrophicus. Carbohydrate utilization by each diazotrophic isolate was examined. Abilities of the isolates to utilize a range of mono-, di-, and polysaccharides largely reflected the predicted availability of organic carbon and energy in the lagoon, except that chitin was not utilized. Biochemical tests on the utilization of combined nitrogen showed that one isolate could utilize nitrate, and that this strain was susceptible to full repression of nitrogenase activity by 10mM nitrate. Urease activity was not detected in any of the isolates. In the absence of molybdenum two of the isolates, a Photobacterium spp. and V. diazotrophicus, reduced acetylene to ethylene and ethane, a property frequently associated with the activity of alternative nitrogenases. Addition of 25µM molybdenum inhibited ethane production by V. diazotrophicus, but stimulated ethylene and ethane production by the Photobacterium isolate. Addition of 28µM vanadium did not appear to regulate ethane production by either strain. Assays of nitrogenase activity in sediments from which some isolates were obtained indicated that molybdenum was not limiting nitrogenase activity at naturally-occurring concentrations. Southern hybridizations of the chromosomes of these strains with the anfH and vnfH genes of Azotobacter vinelandii and the nifH gene of Klebsiella pneumoniae indicated the presence of only one nitrogenase in these isolates.

  14. Diversity of bacteria producing pigmented colonies in aerosol, snow and soil samples from remote glacial areas (Antarctica, Alps and Andes)

    Science.gov (United States)

    González-Toril, E.; Amils, R.; Delmas, R. J.; Petit, J.-R.; Komárek, J.; Elster, J.

    2008-04-01

    Four different communities and one culture of pigmented microbial assemblages were obtained by incubation in mineral medium of samples collected from high elevation snow in the Alps (Mt. Blanc area) and the Andes (Nevado Illimani summit, Bolivia), from Antarctic aerosol (French station Dumont d'Urville) and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas). Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. The phylogenetic comparison with the currently available rDNA database allowed the identification of sequences belonging to Proteobacteria (Alpha-, Beta- and Gamma-proteobacteria), Actinobacteria and Bacteroidetes phyla. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified) and the maritime Antarctic soil the poorest (only one). Snow samples from Col du midi (Alps) and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones). These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteria clone). The only microorganism identified in the maritime Antarctica soil (Brevundimonas sp.) was also detected in the Antarctic aerosol. The two snow samples from the Alps only shared one common microorganism. Most of the identified microorganisms have been detected previously in cold environments (Dietzia kujamenisi, Pseudonocardia Antarctica, Hydrogenophaga palleronii and Brebundimonas sp.), marine sediments (Aquiflexus balticus, Pseudomonas pseudoalkaligenes, Pseudomonas sp. and one uncultured Alphaproteobacteria), and soils and rocks (Pseudonocardia sp., Agrobactrium sp., Limnobacter sp. and two uncultured Alphaproteobacetria clones). Air current dispersal is the best model to explain the presence of very specific microorganisms, like those

  15. Assay Methods for H2S Biogenesis and Catabolism Enzymes

    Science.gov (United States)

    Banerjee, Ruma; Chiku, Taurai; Kabil, Omer; Libiad, Marouane; Motl, Nicole; Yadav, Pramod K.

    2015-01-01

    H2S is produced from sulfur-containing amino acids, cysteine and homocysteine, or a catabolite, 3-mercaptopyruvate, by three known enzymes: cystathionine β-synthase, γ-cystathionase, and 3-mercaptopyruvate sulfurtransferase. Of these, the first two enzymes reside in the cytoplasm and comprise the transsulfuration pathway, while the third enzyme is found both in the cytoplasm and in the mitochondrion. The following mitochondrial enzymes oxidize H2S: sulfide quinone oxidoreductase, sulfur dioxygenase, rhodanese, and sulfite oxidase. The products of the sulfide oxidation pathway are thiosulfate and sulfate. Assays for enzymes involved in the production and oxidative clearance of sulfide to thiosulfate are described in this chapter. PMID:25725523

  16. Counterintuitive alignment of H2(+) in intense femtosecond laser fields.

    Science.gov (United States)

    Frasinski, L J; Plumridge, J; Posthumus, J H; Codling, K; Taday, P F; Divall, E J; Langley, A J

    2001-03-19

    The multiphoton ionization of H2 has been studied using laser pulses of 266 nm wavelength, 250 fs duration, and 5x10(13) W/cm(2) peak intensity. Dissociation of H2(+) via one-photon absorption proceeds through two channels with markedly different proton angular distributions. The lower-energy channel (2.6 eV kinetic energy release) is produced in the bond softening mechanism, which generates parallel alignment. The higher-energy channel (3.5 eV) originates from population trapping in a light-induced bound state, where bond hardening generates orthogonal, counterintuitive alignment.

  17. Diversity of bacteria producing pigmented colonies in aerosol, snow and soil samples from remote glacial areas (Antarctica, Alps and Andes

    Directory of Open Access Journals (Sweden)

    E. González-Toril

    2008-04-01

    Full Text Available Four different communities and one culture of pigmented microbial assemblages were obtained by incubation in mineral medium of samples collected from high elevation snow in the Alps (Mt. Blanc area and the Andes (Nevado Illimani summit, Bolivia, from Antarctic aerosol (French station Dumont d'Urville and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas. Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. The phylogenetic comparison with the currently available rDNA database allowed the identification of sequences belonging to Proteobacteria (Alpha-, Beta- and Gamma-proteobacteria, Actinobacteria and Bacteroidetes phyla. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified and the maritime Antarctic soil the poorest (only one. Snow samples from Col du midi (Alps and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones. These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteria clone. The only microorganism identified in the maritime Antarctica soil (Brevundimonas sp. was also detected in the Antarctic aerosol. The two snow samples from the Alps only shared one common microorganism. Most of the identified microorganisms have been detected previously in cold environments (Dietzia kujamenisi, Pseudonocardia Antarctica, Hydrogenophaga palleronii and Brebundimonas sp., marine sediments (Aquiflexus balticus, Pseudomonas pseudoalkaligenes, Pseudomonas sp. and one uncultured Alphaproteobacteria, and soils and rocks (Pseudonocardia sp.,

  18. A Global PLASIMO Model for H2O Chemistry

    Science.gov (United States)

    Tadayon Mousavi, Samaneh; Koelman, Peter; Graef, Wouter; Mihailova, Diana; van Dijk, Jan; EPG/ Applied Physics/ Eindhoven University of Technology Team; Plasma Matters B. V. Team

    2016-09-01

    Global warming is one of the critical contemporary problems for mankind. Transformation of CO2 into fuels, like CH4, that are transportable with the current infrastructure seems a promising idea to solve this threatening issue. The final aim of this research is to produce CH4 by using microwave plasma in CO2 -H2 O mixture and follow-up catalytic processes. In this contribution we present a global model for H2 O chemistry that is based on the PLASIMO plasma modeling toolkit. The time variation of the electron energy and the species' densities are calculated based on the source and loss terms in plasma due to chemical reactions. The short simulation times of such models allow an efficient assessment and chemical reduction of the H2O chemistry, which is required for full spatially resolved simulations.

  19. An H2A Histone Isotype, H2ac, Associates with Telomere and Maintains Telomere Integrity.

    Directory of Open Access Journals (Sweden)

    Chia-Hsin Su

    Full Text Available Telomeres are capped at the ends of eukaryotic chromosomes and are composed of TTAGGG repeats bound to the shelterin complex. Here we report that a replication-dependent histone H2A isotype, H2ac, was associated with telomeres in human cells and co-immunoprecipitates with telomere repeat factor 2 (TRF2 and protection of telomeres protein 1 (POT1, whereas other histone H2A isotypes and mutations of H2ac did not bi