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Bacteria Isolated (bacteria + isolated)
Kinds of Bacteria Isolated Selected AbstractsAntibacterial Activities of Chitosans and Chitosan Oligomers with Different Molecular Weights on Spoilage Bacteria Isolated from TofuJOURNAL OF FOOD SCIENCE, Issue 4 2002H.K. No ABSTRACT Seven bacteria were isolated from spoiled tofu and identified as Bacillus sp. (S08), B. megaterium (S10), B. cereus (S17, S27, S28, S32), and Enterobacter sakazakii (S35). In a paper disc test with 6 chitosans and 6 chitosan oligomers of different molecular weights, chitosans showed higher antimicrobial activity than did chitosan oligomers at a 0.1% concentration. Results of inhibitory effects of 6 chitosans on growth of Bacillus sp. (S08) failed to detect viable cells after incubation for 24 hrs at 37 C, even at 0.02% concentration. With B. megaterium (S10) and B. cereus (S27), a 3 to 4 log cycle reduction was found in the chitosan-treated group. The growth of Enterobacter sakazakii (S35) was completely suppressed in the presence of 0.04% chitosan except for 1 chitosan product. The minimum inhibitory concentration of chitosan differed with products and isolates, ranging from 0.005% to above 0.1%. [source] Population Dynamics of Pseudomonas syringae pv. tomato Strains on Tomato Cultivars Rio Grande and Rio Grande- Pto under Field ConditionsJOURNAL OF PHYTOPATHOLOGY, Issue 4 2009David K. Willis Abstract We examined the effects of the Pto resistance locus on the population dynamics of Pseudomonas syringae pv. tomato (Pst) strains in field experiments with the nearly isogenic tomato lines Rio Grande (RG, susceptible to Pst races 0 and 1) and Rio Grande-Pto (RG-Pto, resistant to Pst race 0, susceptible to Pst race 1). Pst strain SM78-1Smr (race 0) grew well under field conditions and caused ample bacterial speck disease on susceptible RG plants. In contrast, strain DC3000 failed to establish large populations when inoculated onto field grown RG plants. Mean population sizes of SM78-1Smr were 4,5 orders of magnitude larger on RG than RG-Pto plants indicating that RG-Pto plants were highly effective in attenuating pathogen population development. Most of the sampled leaflets from RG-Pto field plots harboured small numbers of SM78-1Smr. However, population sizes SM78-1Smr as large as 105,106 CFU were found on a few leaflets. Bacteria isolated from these leaflets had phenotypes characteristic of Pst race 1 strains. In growth chamber plant assays, the bacterial strains grew well and caused typical speck lesions on RG-Pto plants. The strains appeared to be race-shift mutants of SM SM78-1Smr. Interestingly, results from DNA hybridization experiments demonstrated that the race-shift mutants were deleted for the avirulence gene, avrPto but not for avrPtoB. [source] Gene diversity of CYP153A and AlkB alkane hydroxylases in oil-degrading bacteria isolated from the Atlantic OceanENVIRONMENTAL MICROBIOLOGY, Issue 5 2010Liping Wang Summary Alkane hydroxylases, including the integral-membrane non-haem iron monooxygenase (AlkB) and cytochrome P450 CYP153 family, are key enzymes in bacterial alkane oxidation. Although both genes have been detected in a number of bacteria and environments, knowledge about the diversity of these genes in marine alkane-degrading bacteria is still limited, especially in pelagic areas. In this report, 177 bacterial isolates, comprising 43 genera, were obtained from 18 oil-degrading consortia enriched from surface seawater samples collected from the Atlantic Ocean. Many isolates were confirmed to be the first oil-degraders in their affiliated genera including Brachybacterium, Idiomarina, Leifsonia, Martelella, Kordiimonas, Parvibaculum and Tistrella. Using degenerate PCR primers, alkB and CYP153A P450 genes were surveyed in these bacteria. In total, 82 P450 and 52 alkB gene fragments were obtained from 80 of the isolates. These isolates mainly belonged to Alcanivorax, Bacillus, Erythrobacter, Martelella, Parvibaculum and Salinisphaera, some of which were reported, for the first time, to encode alkane hydroxylases. Phylogenetic analysis showed that both genes were quite diverse and formed several clusters, most of which were generated from various Alcanivorax bacteria. Noticeably, some sequences, such as those from the Salinisphaera genus, were grouped into a distantly related novel cluster. Inspection of the linkage between gene and host revealed that alkB and P450 tend to coexist in Alcanivorax and Salinisphaera, while in all isolates of Parvibaculum, only P450 genes were found, but of multiple homologues. Multiple homologues of alkB mostly cooccurred in Alcanivorax isolates. Conversely, distantly related isolates contained similar or even identical sequences. In summary, various oil-degrading bacteria, which harboured diverse P450 and alkB genes, were found in the surface water of Atlantic Ocean. Our results help to show the diversity of P450 and alkB genes in prokaryotes, and to portray the geographic distribution of oil-degrading bacteria in marine environments. [source] Reproduction and metabolism at , 10°C of bacteria isolated from Siberian permafrostENVIRONMENTAL MICROBIOLOGY, Issue 4 2003Corien Bakermans Summary We report the isolation and properties of several species of bacteria from Siberian permafrost. Half of the isolates were spore-forming bacteria unable to grow or metabolize at subzero temperatures. Other Gram-positive isolates metabolized, but never exhibited any growth at , 10°C. One Gram-negative isolate metabolized and grew at , 10°C, with a measured doubling time of 39 days. Metabolic studies of several isolates suggested that as temperature decreased below + 4°C, the partitioning of energy changes with much more energy being used for cell maintenance as the temperature decreases. In addition, cells grown at , 10°C exhibited major morphological changes at the ultrastructural level. [source] Characterization of nickel-resistant bacteria isolated from serpentine soilENVIRONMENTAL MICROBIOLOGY, Issue 11 2001A. Mengoni In the present study, heterotrophic nickel-resistant bacteria were isolated and characterized from three different serpentine outcrops in central Italy populated by the nickel-hyperaccumulating plant Alyssum bertolonii. Bacteria were isolated from the rhizosphere of the plant and from soil portions at various distances from the plant. The proportion of nickel-resistant cfu was higher in proximity to the plant than in free soil. A total of 138 isolates was collected and grouped into 47 different operational taxonomic units (OTUs) by means of amplified ribosomal DNA restriction analysis (ARDRA) and into 25 heavy-metal resistant phenotypes. The phylogenetic position of strains belonging to 20 OTUs, representing more than the 70% of the total isolates, was determined by 16S rDNA sequencing. These analyses showed that the most represented genera in all three different outcrops were Pseudomonas and Streptomyces. Pseudomonas strains were found to be predominant in the plant rhizosphere, whereas Streptomyces strains were mainly present in the soil. [source] Isolation and characterization of naphthalene-degrading bacteria from sediments of Cadiz area (SW Spain)ENVIRONMENTAL TOXICOLOGY, Issue 5 2008D. Nair Abstract Petroleum hydrocarbon contamination of harbor sediments from shipping activity, fuel oil spills, and runoffs are becoming a great concern because of the toxicity and recalcitrance of many of the fuel components. Polycyclic aromatic hydrocarbons (PAHs) are of most concern due to their toxicity, low volatility, resistance to degradation, and high affinity for sediments. Microorganisms, especially bacteria, play an important role in the biodegradation of these hydrocarbons. The objective of the present study was to characterize and isolate PAH-(naphthalene) degrading bacteria in the coastal sediments of Cadiz (SW Spain), since this area is mostly polluted by PAH occurrence. A total of 16 naphthalene-utilizing bacteria were isolated from these sites. Introduction of bacteria isolated from contaminated sediments into mineral medium contributed to the increased rate of hydrocarbon utilization. The bacterial isolates obtained from these sites are very potent in utilizing naphthalene and crude oil. It would be interesting to assess if the selected naphthalene-degrading isolates may degrade other compounds of similar structure. Hence these isolates could be very helpful in bioremediating the PAH-contaminated sites. Further pursue on this work might represent eco-friendly solution for oil contamination on sea surface and coastal area. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source] Impact of five selected xenobiotics on isolated ammonium oxidizers and on nitrifying activated sludgeENVIRONMENTAL TOXICOLOGY, Issue 4 2006S. N. Dokianakis Abstract Sewage treatment plants (STPs) are usual receptors of xenobiotic compounds that have to be cotreated with municipal wastewaters before being discharged to the water environment. The presence of organic contaminants, such as surfactants, polycyclic aromatic hydrocarbons (PAHs), phthalates, and their primary degradation products in the influents of STPs may inhibit irreversibly sensitive biological processes, such as nitrification. The first step of nitrification, i.e., the oxidation of ammonium to nitrite (nitritification), is particularly sensitive. Inhibition of this step under uncontrolled conditions may completely inhibit biological nitrogen removal. The aim of this work was to study the possible inhibitory effect of five selected xenobiotics on (a) a mixed culture of ammonium-oxidizing bacteria isolated from activated sludge and (b) nitrifying activated sludge directly. The xenobiotics that were tested include nonylphenols (NP), nonylphenolethoxylates (NPEO), linear alkylbenzene sulfonates (LAS), di(2-ethylhexyl) phthalate (DEHP), as a representative phthalate ester, and the PAH phenanthrene. Remarkable inhibitory effects for all tested compounds were observed in this study even at xenobiotic concentrations as low as 1 mg/L. The observed inhibition of xenobiotics on nitrifying activated sludge was less pronounced, because of the masking effect exerted by the sludge flocs, but was still significant for many of the tested substances at concentrations up to 10 mg/L. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 310,316, 2006. [source] A survey of equine abortion, stillbirth and neonatal death in the UK from 1988 to 1997EQUINE VETERINARY JOURNAL, Issue 5 2003K. C. SMITH Summary Reasons for performing study: A detailed review of laboratory records for equine abortion is fundamental in establishing current disease trends and suggesting problems important for further research. Objectives: To review the causes of abortion and neonatal death in equine diagnostic submissions to the Animal Health Trust over a 10 year period. Methods: The diagnoses in 1252 equine fetuses and neonatal foals were reviewed and analysed into categories. Results: Problems associated with the umbilical cord, comprising umbilical cord torsion and the long cord/cervical pole ischaemia disorder, were the most common diagnoses (38.8%: 35.7% umbilical cord torsion and 3.1% long cord/cervical pole ischaemia disorder). Other noninfective causes of abortion or neonatal death included twinning (6.0%), intrapartum stillbirth (13.7%) and placentitis, associated with infection (9.8%). E. coli and Streptococcus zooepidemicus were the most common bacteria isolated. Neonatal infections not associated with placentitis accounted for 3.2% of incidents; and infections with EHV-1 or EHV-4 for 6.5%. Conclusions: Definitive diagnosis of equine abortion is possible in the majority of cases where the whole fetus and placenta are submitted for examination. Potential relevance: Given the high incidence of umbilical cord torsion and related problems as causes of abortion in UK broodmares, more research on factors determining umbilical cord length and risk of torsion is essential. [source] Phylogenetic diversity of non-nodulating Rhizobium associated with pine ectomycorrhizaeFEMS MICROBIOLOGY ECOLOGY, Issue 3 2009Megumi Tanaka Abstract Most Rhizobium species described are symbionts that form nodules on legume roots; however, non-nodulating strains of Rhizobium are also widespread in nature. Unfortunately, knowledge of non-nodulating Rhizobium is quite limited compared with nodulating Rhizobium. Here, we studied the phylogenetic diversity of Rhizobium species that inhabit Japanese red pine roots (Pinus densiflora). Because fine roots of pine trees are usually colonized by ectomycorrhizal fungi in nature, we mainly used ectomycorrhizal root tips for bacterial isolation. Out of 1195 bacteria isolated from 75 independent root samples from the field and greenhouse experiments, 102 isolates were confirmed to be Rhizobium following partial 16S rRNA gene analysis. Rhizobium species were occasionally dominant in culturable bacterial communities, whereas no Rhizobium species were isolated from the soil itself. Molecular phylogenetic analyses using 16S rRNA, atpD, and recA gene sequences revealed that isolated Rhizobium strains were phylogenetically diverse and that several were distantly related to known Rhizobium species. Considering that a single species of pine is associated with unique and phylogenetically diverse Rhizobium populations, we should pay more attention to non-nodulating strains to better understand the diversity, ecology, and evolution of the genus Rhizobium and plant,Rhizobium associations. [source] Utilization of mixtures of polycyclic aromatic hydrocarbons by bacteria isolated from contaminated sedimentFEMS MICROBIOLOGY ECOLOGY, Issue 1 2002Deborah Dean-Ross Abstract The ability of sediment bacteria to utilize polycyclic aromatic hydrocarbons (PAHs) when present as components of mixtures was investigated. One strain, identified as Mycobacterium flavescens, could utilize fluoranthene in the presence of pyrene, although utilization of pyrene was slower in the presence of fluoranthene than in its absence. The second strain, a Rhodococcus species, could utilize fluoranthene in the presence of anthracene, although the presence of fluoranthene slowed the rate of utilization of anthracene. Cometabolism of fluoranthene in these strains was confirmed by the isolation of metabolites of fluoranthene and by kinetic analysis of the rate of utilization of the growth substrate in the presence of fluoranthene. In both strains, metabolism of fluoranthene occurred on the fused ring of the fluoranthene molecule, producing 9-fluorenone-1-carboxylic acid. In the Rhodococcus sp., a second metabolite, a-(carboxymethylene)fluorene-1-carboxylic acid, was identified, indicating that this strain has the capacity to metabolize fluoranthene via ortho as well as meta cleavage. The presence of PAHs in a mixture produces interactive effects which can either increase or decrease the rate of utilization of individual PAHs, results which need to be taken into account when estimating rates of degradation in contaminated environments. [source] Isolation and identification of equol-producing bacterial strains from cultures of pig faecesFEMS MICROBIOLOGY LETTERS, Issue 1 2008Zhuo-Teng Yu Abstract Transformation of daidzein to equol was compared during fermentation of three growth media inoculated with faeces from Erhualian piglets, but equol was produced from only one medium, M1. Two equol-producing strains (D1 and D2) were subsequently isolated using medium M1. Both strains were identified as Eubacterium sp., on the basis of morphological and physiological characteristics, and 16S rRNA gene sequence analysis showed that strains D1 and D2 were most closely related to previously characterized daidzein-metabolizing bacteria isolated from human faecal and rumen samples, respectively. This suggests that the ability to metabolize daidzein can be found among bacteria present within the mammalian intestine. The results provided the first account of conversion of daidzein directly to equol by bacterial species from farm animals. These strains may be of importance to the improvement of animal performance, and the use of medium M1 could provide a simple way to isolate bacterial strains capable of transforming daidzein into equol. [source] Response to alkaline stress by root canal bacteria in biofilmsINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2007L. E. Chávez de Paz Abstract Aim, To determine whether bacteria isolated from infected root canals survive alkaline shifts better in biofilms than in planktonic cultures. Methodology, Clinical isolates of Enterococcus faecalis, Lactobacillus paracasei, Olsenella uli, Streptococcus anginosus, S. gordonii, S. oralis and Fusobacterium nucleatum in biofilm and planktonic cultures were stressed at pH 10.5 for 4 h, and cell viability determined using the fluorescent staining LIVE/DEAD BacLight bacterial viability kit. In addition, proteins released into extracellular culture fluids were identified by Western blotting. Results,Enterococcus faecalis, L. paracasei, O. uli and S. gordonii survived in high numbers in both planktonic cultures and in biofilms after alkaline challenge. S. anginosus, S. oralis and F. nucleatum showed increased viability in biofilms compared with planktonic cultures. Alkaline exposure caused all planktonic cultures to aggregate into clusters and resulted in a greater extrusion of cellular proteins compared with cells in biofilms. Increased levels of DnaK, HPr and fructose-1,6-bisphosphate aldolase were observed in culture fluids, especially amongst streptococci. Conclusions, In general, bacteria isolated from infected roots canals resisted alkaline stress better in biofilms than in planktonic cultures, however, planktonic cells appeared to use aggregation and the extracellular transport of specific proteins as survival mechanisms. [source] Enzymes involved in flavour formation by bacteria isolated from the smear population of surface-ripened cheeseINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 1 2004A G Williams Twenty-five bacterial isolates recovered from the surface population of smear-ripened cheese were assigned phenotypically as Brevibacterium spp., Corynebacterium spp. and Aureobacterium spp. using the Biolog GP2 microplate system and database. The range and activity of hydrolytic enzymes involved in the formation of cheese flavour constituents were monitored in cell-free lysates of the isolates. Esterase activity and the presence of a range of enzymes involved in amino acid release and breakdown was confirmed in all strains examined although there were pronounced interspecies and strain differences in the level of activity detected. Peptidolytic activities present in the smear bacteria included dipeptidyl peptidase and aminopeptidases that cleaved various N-terminal amino acids including proline. Subsequent breakdown of the released aromatic and branched-chain amino acids was mediated by ,-keto acid dependent aminotransferase action and several of the isolates were able to form thiols from sulphur-containing amino acid precursors. It was confirmed that the enzymic activity of the smear population could be manipulated by the use of defined starter cultures comprising selected combinations of smear isolates. The hydrolytic activities of the smear bacteria are involved in the generation of cheese flavour compounds and the enzyme profile is thus an important selection criterion for strains to be evaluated for use in defined surface smear preparations. [source] Resistant Pathogens in Urinary Tract InfectionsJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 2002Lindsay E. Nicolle MD Antimicrobial susceptibility of bacteria causing urinary tract infection (UTI) has evolved over several decades as antimicrobial exposure has repeatedly been followed by emergence of resistance. Older populations in the community, long-term care facilities, or acute care facilities have an increased prevalence of resistant bacteria isolated from UTI. Resistant isolates are more frequent in long-term care populations than the community. Resistant isolates include common uropathogens, such as Escherichia coli or Proteus mirabilis, and organisms with higher levels of intrinsic resistance, such as Pseudomonas aeruginosa or Providencia stuartii. Isolation of resistant organisms is consistently associated with prior antimicrobial exposure and higher functional impairment. The increased likelihood of resistant bacteria makes it essential that a urine specimen for culture and susceptibility testing be obtained before instituting antimicrobial therapy. Therapy for the individual patient must be balanced with the possibility that antimicrobial use will promote further resistance. Antimicrobial therapy should be avoided unless there is a clear clinical indication. In particular, asymptomatic bacteriuria should not be treated with antimicrobials. Where symptoms are mild or equivocal, urine culture results should be obtained before initiating therapy. This permits selection of specific therapy for the infecting organism and avoids empiric, usually broad-spectrum, therapy. Where empirical therapy is necessary, prior infecting organisms should be isolated, and recent antimicrobial therapy, as well as regional or facility susceptibility patterns, should be considered in antimicrobial choice. Where empirical therapy is used, it should be reassessed 48 to 72 hours after initiation, once pretherapy cultures are available. [source] Probiotic characteristics of lactic acid bacteria isolated from kimchiJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2010J.-H. Chang Abstract Aims:, The present work was aimed at identifying strains of lactic acid bacteria (LAB) from kimchi, with properties suitable for use as starter cultures in yogurt fermentation. Methods and Results:, A total of 2344 LAB strains were obtained from two different sources, one group consisted of commercial LAB strains from kimchi, and the second group consisted of those strains isolated from various types of kimchi. The LAB strains from both groups were screened for resistance to biological barriers (acid and bile salts), and the four most promising strains were selected. Further analysis revealed that KFRI342 of the four selected strains displayed the greatest ability to reduce the growth of the cancer cells, SNU-C4. The in vivo efficacy of strains in quinone reductase induction assay was evaluated, and the extent of DNA strand breakage in individual cells was investigated using the comet assay. Strain KFRI342 was identified as Lactobacillus acidophilus by 16S rRNA sequence analysis, showed protection against tumour initiation and imparted immunostimulation as well as protection against DNA damage. Conclusions:, Strain KFRI342, which showed probiotic characteristics reducing cancer cell growth, could be a suitable starter culture for yogurt fermentation because of its strong acid production and high acid tolerance. Significance and Impact of the Study:, This is the first report to describe a bacterium, isolated from kimchi, Lact. acidophilus KFRI342 which has the probiotic characteristics and the acid tolerance needed for its use as a starter culture in yogurt fermentation. [source] Investigation of critical inter-related factors affecting the efficacy of pulsed light for inactivating clinically relevant bacterial pathogensJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2010H.P. Farrell Abstract Aims:, To investigate critical electrical and biological factors governing the efficacy of pulsed light (PL) for the in vitro inactivation of bacteria isolated from the clinical environment. Development of this alternative PL decontamination approach is timely, as the incidence of health care,related infections remains unacceptably high. Methods and Results:, Predetermined cell numbers of clinically relevant Gram-positive and Gram-negative bacteria were inoculated separately on agar plates and were flashed with ,60 pulses of broad-spectrum light under varying operating conditions, and their inactivation measured. Significant differences in inactivation largely occurred depending on the level of the applied lamp discharge energy (range 3·2,20 J per pulse), the amount of pulsing applied (range 0,60 pulses) and the distance between light source and treatment surface (range 8,20 cm) used. Greater decontamination levels were achieved using a combination of higher lamp discharge energies, increased number of pulses and shorter distances between treatment surface and the xenon light source. Levels of microbial sensitivity also varied depending on the population type, size and age of cultures treated. Production of pigment pyocynanin and alginate slime in mucoid strains of Pseudomonas aeruginosa afforded some protection against lethal action of PL; however, this was evident only by using a combination of reduced amount of pulsing at the lower lamp discharge energies tested. A clear pattern was observed where Gram-positive bacterial pathogens were more resistant to cidal effects of PL compared to Gram negatives. While negligible photoreactivation of PL-treated bacterial strains occurred after full pulsing regimes at the different lamp discharge energies tested, some repair was evident when using a combination of reduced pulsing at the lower lamp discharge energies. Strains harbouring genes for multiple resistances to antibiotics were not significantly more resistant to PL treatments. Slight temperature rises (,4·2°C) were measured on agar surfaces after extended pulsing at higher lamp discharge energies. Presence of organic matter on treatment surface did not significantly affect PL decontamination efficacy, nor did growth of PL-treated bacteria on selective agar diminish survival compared to similarly treated bacteria inoculated and enumerated on nonselective agar plates. Conclusions:, Critical inter-related factors affecting the effective and repeatable in vitro decontamination performance of PL were identified during this study that will aid further development of this athermal process technology for applications in health care and in industry. Very rapid reductions (c. 7 log10 CFU cm,2 within ,10 pulses) occurred using discharge energy of 20 J for all tested clinically relevant bacteria under study when treated at 8 cm distance from xenon light source. While no resistant flora is expected to develop for treatment of microbial pathogens on two-dimensional surfaces, careful consideration of scale up factors such as design and operational usage of this PL technique will be required to assure operator safety. Significance and Impact of the Study:, Findings and conclusions derived from this study will enable further development and optimization of this decontamination technique in health care and in food preparation settings, and will advance the field of nonthermal processing technologies. [source] Characterization of Pasteurellaceae-like bacteria isolated from clinically affected psittacine birdsJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2010R.H. Gregersen Abstract Aims:, The aim of the present investigation was to identify and characterize Pasteurella -like isolates obtained from clinically affected psittacine birds. Methods and Results:, A total of 37 isolates from psittacine birds tentatively classified with the family Pasteurellaceae were characterized phenotypically. The genetic relationship was investigated by sequencing of partial rpoB and 16S rRNA genes for selected isolates. The results obtained were compared with the data from 16 reference strains. Nine isolates were identified as Gallibacterium spp., 16 as Volucribacter spp. or Volucribacter- like, while 11 isolates were classified as taxon 44 of Bisgaard. A single isolate was identified as Pasteurella multocida. Conclusions:, Characterization of Pasteurellaceae by traditional methods is often inconclusive because of inconsistent reactions and phenotypic diversity. For the same reason, genotyping is essential to allow proper classification as demonstrated in the present study. Significance and Impact of the Study:, Limited information exists on the isolation and significance of Pasteurellaceae associated with clinically affected psittacine birds showing signs of digestive and/or respiratory disorders. The present investigations demonstrated that these organisms are widely distributed among clinically affected birds, but isolation of these taxa cannot be unambiguously correlated with the symptoms observed. [source] Genetic correlation between chromium resistance and reduction in Bacillus brevis isolated from tannery effluentJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2009T. Verma Abstract Aims:, To investigate the genetic basis of Cr(VI) resistance and its reduction to Cr(III) in indigenous bacteria isolated from tannery effluent. Methods and Results:, Four bacteria resistant to high Cr(VI) levels were isolated and identified as Bacillus spp. Their Cr(VI) reduction ability was tested. To assess the genetic basis of Cr(VI) resistance and reduction, plasmid transfer and curing studies were performed. Among all, B. brevis was resistant to 180 ,g Cr(VI) ml,1 and showed the greatest degree of Cr(VI) reduction (75·8%) within 28 h and its transformant was resistant to 160 ,g Cr(VI) ml,1 and reduced 69·9% chromate. It harboured a stable 18 kb plasmid DNA. Transfer and curing studies revealed that both the chromate resistance and reduction were plasmid mediated. The presence of other metal cations did not have any significant effect on Cr(VI) bioreduction. Conclusions:,Bacillus brevis was resistant to elevated Cr(VI) levels and may potentially reduce it in short time from an environment where other metal ions are also present in addition to chromium ions. The strain tested shows a positive correlation between genetic basis of Cr(VI) resistance and reduction. Significance and Impact of the Study:, To our knowledge, this is the first study on the genetic correlation between chromium resistance and reduction in bacteria. Such strains may potentially be useful in biotechnological applications and in situ Cr(VI) bioremediation. [source] Evaluation of the fermentability of oat fractions obtained by debranning using lactic acid bacteriaJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2008G. Kedia Abstract Aims:, The overall kinetics of the fermentation of four oat fractions obtained by debranning using three potentially probiotic lactic acid bacteria were investigated. The main objective was to study the suitability of these fractions as fermentation media for the growth and the metabolic production of bacteria isolated from human intestine. Methods and Results:, The cell growth, lactic acid production and substrate uptakes of the three lactobacilli was monitored for 30 h. An unstructured mathematical model was used to describe and fit the experimental data. In the medium from fraction B (1,3% pearlings or ,-glucan-rich fraction) all strains reached the highest cell populations, maximum growth rates and maximum lactic acid productions. This could be because of the high levels of total fibre and ,-glucan of this fraction. Limited growth and lactic acid formation was found in medium A (0,1% pearlings or bran-rich fraction). Conclusions:, Medium B (1,3% pearling fraction) is the most suitable for fermentation and produces considerably higher probiotic cell concentrations. Significance and Impact of the Study:, Debranning technology could be used to separate fractions from cereal grains for the production of functional formulations with higher probiotic levels than the ones that were obtained with the whole grain. [source] Preliminary characterization of lactic acid bacteria isolated from Zlatar cheeseJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2007K. Veljovic Abstract Aims:, Isolation, characterization and identification of lactic acid bacteria (LAB) from artisanal Zlatar cheese during the ripening process and selection of strains with good technological characteristics. Methods and Results:, Characterization of LAB was performed based on morphological, physiological and biochemical assays, as well as, by determining proteolytic activity and plasmid profile. rep-polymerase chain reaction (PCR) analysis and 16S rDNA sequencing were used for the identification of LAB. PCR analysis was performed with specific primers for detection of the gene encoding nisin production. Strains Lactobacillus paracasei subsp. paracasei, Lactobacillus plantarum, Lactobacillus brevis, Lactococcus lactis subsp. lactis, Enterococcus faecium and Enterococcus faecalis were the main groups present in the Zlatar cheese during ripening. Conclusions:, Temporal changes in the species were observed during the Zlatar cheese ripening. Mesophilic lactobacilli are predominant microflora in Zlatar cheese. Significance and Impact of the Study:, In this study we determined that Zlatar cheese up to 30 days old could be used as a source of strains for the preparation of potential starter cultures in the process of industrial cheese production. As the Serbian food market is adjusting to European Union regulations, the standardization of Zlatar cheese production by using starter culture(s) based on autochtonous well-characterized LAB will enable the industrial production of this popular cheese in the future. [source] Purification and characterization of two bacteriocins produced by lactic acid bacteria isolated from Mongolian airagJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2006B. Batdorj Abstract Aims:, The aim of this study was to isolate and identify bacteriocin-producing lactic acid bacteria (LAB) issued from Mongolian airag (traditional fermented mare's milk), and to purify and characterize bacteriocins produced by these LAB. Methods and Results:, Identification of the bacteria (Enterococcus durans) was carried out on the basis of its morphological, biochemical characteristics and carbohydrate fermentation profile and by API50CH kit and 16S rDNA analyses. The pH-neutral cell-free supernatant of this bacterium inhibited the growth of several Lactobacillus spp. and food-borne pathogens including Escherichia coli, Staphylococcus aureus and Listeria innocua. The antimicrobial agent (enterocin A5-11) was heat stable and was not sensitive to acid and alkaline conditions (pH 2,10), but was sensitive to several proteolytic enzymes. Its inhibitory activity was completely eliminated after treatment with proteinase K and , -chymotrypsin. The activity was however not completely inactivated by other proteases including trypsin and pepsin. Three-step purification procedure with high recovery yields was developed to separate two bacteriocins. The applied procedure allowed the recovery of 16% and 64% of enterocins A5-11A and A5-11B, respectively, present in the culture supernatant with purity higher than 99%. SDS-PAGE analyses revealed that enterocin A5-11 has a molecular mass of 5000 Da and mass spectrometry analyses demonstrates molecular masses of 5206 and 5218 Da for fractions A and B, respectively. Amino acid analyses of both enterocins indicated significant quantitative difference in their contents in threonine, alanine, isoleucine and leucine. Their N -termini were blocked hampering straightforward Edman degradation. Conclusions:, Bacteriocins A5-11A and B from Ent. durans belong to the class II of bacteriocins. Significance and Impact of the Study:, Judging from molecular masses, amino acid composition and spectrum of activities, bacteriocins A5-11A and B from Ent. durans show high degree of similarity with enterocins L50A and L50B isolated from Enterococcus faecium (Cintas et al. 1998, 2000) and with enterocin I produced by Ent. faecium 6T1a, a strain originally isolated from a Spanish-style green olive fermentation (Floriano et al. 1998). [source] Antilisterial activity of lactic acid bacteria isolated from rigouta, a traditional Tunisian cheeseJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2004T. Ghrairi Abstract Aims:, Screening for lactic acid bacteria (LAB) producing bacteriocins and other antimicrobial compounds is of a great significance for the dairy industry to improve food safety. Methods and Results:, Six-hundred strains of LAB isolated from ,rigouta', a Tunisian fermented cheese, were tested for antilisterial activity. Eight bacteriocinogenic strains were selected and analysed. Seven of these strains were identified as Lactococcus lactis and produced nisin Z as demonstrated by mass spectrometry analysis of the purified antibacterial compound. Polymerase chain reaction experiments using nisin gene-specific primers confirmed the presence of nisin operon. Plasmid profiles analysis suggests the presence of, at least, three different strains in this group. MMT05, the eighth strain of this antilisterial collection was identified, at molecular level, as Enterococcus faecalis. The purified bacteriocin produced by this strain showed a molecular mass of 10 201·33 ± 0·85 Da. This new member of class III bacteriocins was termed enterocin MMT05. Conclusions:, Seven lactococcal strains producing nisin Z were selected and could be useful as bio-preservative starter cultures. Additional experiments are needed to evaluate the promising strain MMT05 as bio-preservative as Enterococci could exert detrimental or beneficial role in foods. Significance and Impact of the Study:, Only a few antibacterial strains isolated from traditional African dairy products were described. The new eight strains described herein contribute to the knowledge of this poorly studied environment and constitute promising strains for fermented food safety. [source] Phylogenetic analysis by 16S rDNA gene sequence comparison of avian taxa of Bisgaard and characterization and description of two new taxa of PasteurellaceaeJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2003H. Christensen Abstract Aims: Characterization and classification of members of Pasteurellaceae isolated from birds by extended phenotypic characterization and 16S rDNA gene sequence comparison. Methods and Results: A total of 95 avian isolates were subjected to extended phenotypic characterization. Thirteen bacterial strains selected from main phenotypic clusters and isolated from parrot, parakeet, budgerigar, partridge, pheasant, chicken, duck, hawk and gull were subsequently characterized by 16S rDNA gene sequencing. Eight of the sequenced strains were classified with six taxa of Bisgaard of which two (34 and 40) have not been published before, and the properties of four others (14, 22, 26 and 32) changed upon the characterization of these new isolates. Of the remaining strains, one was identified as a phenotypic variant in maltose and dextrin of Pasteurella gallinarum another as a trehalose positive variant of taxon 3 of Bisgaard. The remaining three strains sequenced were not closely related to existing taxa of Pasteurellaceae. However, they were found to belong to the Avian cluster with 92,97% 16S rDNA gene sequence similarity. Conclusion: The study allowed the classification of bacteria isolated from birds by the integrated use of extended phenotypic characterization and 16S rDNA gene sequence analysis. Only the application of 16S rDNA gene sequencing allows a correct identification of variant strains. Significance and Impact of the Study: The description of new taxa within the bacterial family Pasteurellaceae will subsequently allow additional isolates of these taxa to be identified and improve the diagnosis and epidemiological understanding of bacteria causing disease in birds. [source] Phenotypic and genotypic characterization of competitive exclusion products for use in poultryJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2003R.D. Wagner Abstract Aims: Phenotypic and genotypic bacteria identification methods were compared for their efficacy in determining the composition of competitive exclusion (CE) products. Methods and Results: Phenotypic methods used for bacterial identification were fatty acid methyl ester profiles, biochemical assays and carbohydrate utilization profiles. Genotypic methods were MicroSeq16S rRNA sequence analysis and BLAST searches of the GenBank sequence database. Agreement between phenotypic and genotypic methods for identification of bacteria isolated from the Preempt CE product was 20%. A defined test mixture of bacteria was identified to the species level 100% by BLAST analysis, 64% by MicroSeq and 36% by phenotypic techniques. Conclusions: The wide range of facultative and obligate anaerobic bacteria present in a CE product are more accurately identified with 16S rRNA sequence analyses than with phenotypic identification techniques. Significance and Impact of the Study: These results will provide guidelines for manufacturers of CE products to submit more reliable product information for market approval by regulatory agencies. [source] Feather keratin hydrolysis by a Vibrio sp. strain kr2JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2000S. Sangali The aim of the study was to characterize feather-degrading bacteria isolated from poultry industry waste. A Vibrio sp. strain kr2 producing a high keratinolytic activity when cultured on native feather-containing broth was isolated. The bacterium grew with an optimum at pH 6·0 and 30 °C, where maximum feather-degrading activity was also observed. Keratinase production was similar at both 25 and 30 °C, while the maximum concentration of soluble protein was reached at 30 °C. Reduction of disulphide bridges was also observed, increasing with cultivation time. The keratinase of strain kr2 was active on azokeratin, azocasein, benzoyl-arginine- p -nitroanilide and Ala-Ala- p -nitroanilide as substrates. The amino acid composition of the feather hydrolysate was determined, presenting similarities with that reported for feather lysate, feather meal and raw feathers. A novel feather-degrading bacterium was isolated and characterized, showing high keratinolytic activity. Complete feather degradation was achieved during cultivation. Strain kr2 shows potential for use for biotechnological processes involving keratin hydrolysis. [source] Antimicrobial profiles of periodontal pathogens isolated from periodontitis patients in the Netherlands and SpainJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 8 2005A. J. Van Winkelhoff Abstract Background and Aim: Antimicrobial resistance of periodontal pathogens towards currently used antibiotics in periodontics has been investigated in a previous study. Microbial resistance in the periodontal microflora was more frequently observed in Spanish patients in comparison with Dutch patients. The aim of the present study was to compare antimicrobial susceptibility profiles of five periodontal bacteria isolated from periodontitis patients in Spain and in the Netherlands. Material and Methods: Subgingival plaque samples from adult patients with periodontitis were collected and cultured on selective and non-selective plates. Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Micromonas micros were isolated and used for minimal inhibitory concentration tests using the Epsilometer (E-test) technique. Eight different antibiotics were tested on all bacterial isolates. MIC50 and MIC90 values for each antibiotic and each species were determined and the percentage of resistant strains was calculated. Results: Significantly higher MIC values were noted in Spanish strains of F. nucleatum for penicillin, ciprofloxacin, of P. intermedia for penicillin, amoxicillin and tetracycline, of M. micros for tetracycline, amoxicillin and azithromycin, and of P. gingivalis for tetracycline and ciprofloxacin. Based on breakpoint concentrations, a higher number of resistant strains in Spain were found in F. nucleatum for penicillin, amoxicillin and metronidazole, in Prevotella intermedia for tetracycline and amoxicillin, and in A. actinomycetemcomitans for amoxicillin and azithromycin. Resistance of P. gingivalis strains was not observed for any of the antibiotics tested both in Spain and the Netherlands. Conclusions: Differences exist in the susceptibility profiles of periodontal pathogens isolated from periodontitis patients in Spain and in the Netherlands. This implicates that antibiotic susceptibility testing is necessary to determine efficacy of antimicrobial agents. Also, clinical studies with antibiotics should take these differences into account. The information from the present study indicates that it may not be possible to develop uniform protocols for usage of antibiotics in the treatment of severe periodontitis in the European Union. [source] Shelf Life and Microbial Quality of Fresh-cut Mango Cubes Stored in High CO2 AtmospheresJOURNAL OF FOOD SCIENCE, Issue 1 2005Jutatip Poubol ABSTRACT: Fresh-cut,Carabao'and,Nam Dokmai'mango cubes were stored in air or in high CO2 atmospheres (3%, 5%, and 10%) at 5 °C and 13 °C. Freshly sliced,Carabao'mango cubes had a lower respiration rate and total bacterial count and higher L-ascorbic acid content and firmness than,Nam Dokmai'mango cubes. The shelf life of fresh-cut mango, based on browning discoloration and water-soaked appearance, was 6 d at 5 °C and 4 d at 13 °C for,Carabao'and 2 d at 5 °C and less than 1 d at 13 °C for,Nam Dokmai'. High CO2 atmospheres retarded the development of water-soaked,Carabao'cubes at 5 °C and 13 °C and,Nam Dokmai'cubes at 5 °C. Texture of,Carabao'cubes was enhanced by high CO2, but ethanol and L-ascorbic acid contents were not affected at 5 °C and 13 °C. Total bacterial count was lower in,Carabao'cubes than in,Nam Dokmai'cubes during storage at both temperatures, and a 10% CO2 only reduced the bacterial count on,Carabao'and,Nam Dokmai'cubes stored at 13 °C. Bacterial flora in,Nam Dokmai'mango cubes consisted mostly of Gram-negative rods assigned primarily to phytopathogenic bacteria such as Pantoea agglomerans and Burkholderia cepacia. The genera of bacteria isolated from cubes stored in 10% CO2 were similar to those from cubes on the initial day. [source] Resident bacteria in a mixed population of rhesus macaque (Macaca mulatta) monkeys: a prevalence studyJOURNAL OF MEDICAL PRIMATOLOGY, Issue 6 2009C.A. Carrier Abstract Background, Microflora populations residing in oropharyngeal and gastrointestinal sites defend against pathogenic bacterial colonization. Perturbations in these microbial communities may allow opportunistic pathogenic bacteria to establish themselves and cause morbidity and mortality from sepsis particularly after stressful experimental procedures. This study determined the prevalent facultative bacteria in a resident population of Macaca mulatta prior to use in experimentally induced immunosuppressive radiation studies. Methods, Standard microbiological methods were used to assess prevalent facultative bacteria in the oropharynx and rectum of 24 male M. mulatta. Results, The majority of the bacteria isolated from the oropharyngeal and rectal sites were gram-positive cocci. Species of Staphylococcus and Streptococcus predominated in all samples. Few gram-negative bacteria were isolated. Conclusions, Bacteriological assessment is recommended to identify predominant bacterial species to be prepared to provide appropriate antimicrobial therapy in non-human primates that are expected to undergo stressful immunocompromising procedures. [source] Biofilm formation by bacteria isolated from retrieved failed prosthetic hip implants in an in vitro model of hip arthroplasty antibiotic prophylaxisJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2007M.M. Tunney Abstract Bacterial infection primarily with Staphylococcus spp. and Propionibacterium acnes remains a significant complication following total hip replacement. In this in vitro study, we investigated the efficacy of gentamicin loading of bone cement and pre- and postoperative administration of cefuroxime in the prevention of biofilm formation by clinical isolates. High and low initial inocula, representative of the number of bacteria that may be present at the operative site as a result of overt infection and skin contamination, respectively, were used. When a high initial inoculum was used, gentamicin loading of the cement did not prevent biofilm formation by the 10 Staphylococcus spp. and the 10 P. acnes isolates tested. Similarly, the use of cefuroxime in the fluid phase with gentamicin-loaded cement did not prevent biofilm formation by four Staphylococcus spp. and four P. acnes isolates tested. However, when a low bacterial inoculum was used, a combination of both gentamicin-loaded cement and cefuroxime prevented biofilm formation by these eight isolates. Our results indicate that this antibiotic combination may protect against infection after intra-operative challenge with bacteria present in low numbers as a result of contamination from the skin but would not protect against bacteria present in high numbers as a result of overt infection of an existing implant. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:2,10, 2007 [source] A retrospective study of the clinical presentation of 140 dogs and 39 cats with bacteraemiaJOURNAL OF SMALL ANIMAL PRACTICE, Issue 8 2008M. Greiner Objectives: To evaluate retrospective data from 140 dogs and 39 cats with positive blood cultures that were presented to the Clinic for Small Animal Medicine in Munich from 1995 to 2004. Methods: The identity of bacteria isolated from blood cultures of dogs and cats with bacteraemia was determined, and clinical and laboratory findings and outcome of animals with Gram-negative versus Gram-positive bacteraemia were compared. Results: Sepsis was diagnosed in 81·7 per cent of dogs and 59·5 per cent of cats with bacteraemia. Escherichia coli was isolated in one third of the animals. Dogs with bacteraemia more often showed monocytosis and increased alkaline phosphatase activity, while in cats, hyperglycaemia was found more commonly. Dogs with Gram-negative bacteraemia had hypoalbuminaemia significantly more often than dogs with Gram-positive bacteraemia, while among the remaining parameters, there were no statistically significant differences. Clinical Significance: Not all dogs and cats with a positive blood culture met the criteria for sepsis. Bacteraemia caused by Gram-positive versus Gram-negative bacteria cannot be distinguished based on clinical or laboratory parameters, and bacterial culture and susceptibility testing have to be performed for the right choice of antibiotic treatment. [source] | ||||||||||||||||||||||||||||||||||