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Different Growth Media (different + growth_media)
Selected AbstractsEffect of various growth media upon survival during storage of freeze-dried Enterococcus faecalis and Enterococcus duransJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2003A.S. Carvalho Abstract Aims: The effects of three different growth media (MRS, M17 and Lee's) on survival during freeze-drying and subsequent storage of six strains of Enterococcus faecalis and two strains of E. durans were investigated. Methods and Results: Distinct Enterococcus spp. strains were grown on M17, MRS and Lee's broth, freeze-dried and stored at 20°C in air under darkness. At regular intervals throughout storage, freeze-dried samples were rehydrated and then plated on M17 agar. Conclusions: A higher survival rate during storage of dried E. durans was obtained when growth occurred in MRS. The same effect was not observed, however, for the majority of E. faecalis strains, which clearly survived better in the dried state when this organism had been grown in M17 or Lee's medium. Significance and Impact of Study: The survival of the dried Enterococcus spp. tested during storage was shown to be strain-specific and dependent on the growth medium. [source] Different combinations of salts affect the growth and bacteriocin production by Lactobacillus salivarius CRL 1328JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2010María Silvina Juárez Tomás Abstract BACKGROUND: The culture medium for optimal growth of vaginal Lactobacillus salivarius CRL 1328 is different from that for optimal bacteriocin production. To simultaneously obtain high amount of biomass and bacteriocin of this microorganism, the effects of different basal culture media and salts on both responses were evaluated. The study was performed by using a complete factorial experimental design 26, with central points. Sixty-four different growth media, which resulted from the combinations of two basal culture media and two concentrations of five salts (ammonium citrate, sodium acetate, MgSO4, MnSO4, and K2HPO4) were assayed. RESULTS: Only the addition of MnSO4 to each culture medium significantly stimulated the growth of L. salivarius. The presence of sodium acetate or MgSO4 stimulated the bacteriocin production, while MnSO4 and K2HPO4 exerted an inhibitory effect. However, the simultaneous addition of MnSO4 and sodium acetate to both basal culture media allowed high bacteriocin levels to be reached, attenuating the inhibitory effect of Mn2+. CONCLUSIONS: The application of a complete experimental design contributed to simultaneous optimization of the biomass and bacteriocin production of L. salivarius CRL 1328. The results obtained are potentially applicable to the technological production of probiotic bacteria and antagonistic substance to be included in a probiotic pharmaceutical product. Copyright © 2009 Society of Chemical Industry [source] ISOLATION AND CHARACTERIZATION OF BACTERIOCIN-PRODUCING MICROORGANISMS FROM AGOS-OSJOURNAL OF FOOD SAFETY, Issue 3 2000JULIE D. TAN ABSTRACT Agos-os, a fermented meat and sweetpotato mixture, was produced and analyzed for its microbial characteristics. pH decreased during fermentation. Mold and anaerobic bacterial counts increased while yeasts and aerobic bacterial counts decreased during the third and seventh day of fermentation. Six isolates with the widest zones of inhibition on the indicator lawn were selected for bacteriocin production. These isolates had exactly the same morphological, physiological and biochemical characteristics. The ribosomal RNA sequence was 99.5% identical with Enterococcus faecalis VRE 1492. The identification was confirmed through DNA homology test by the EMBL Genbank, Canada. This bacterium produced the L-isomer lactic acid. The amount of bacteriocin produced by the bacterium was optimized by growing the bacterium at different growth media, initial pH and fermentation time. Maximum production of bacteriocin was achieved in MRS (De Man Rugosa and Sharpe) medium (with glucose) at pH 7.50. The crude bacteriocin inhibited the growth of gram-positive bacteria such as Lactobacillus sake 15521 and Listeria innocua. The gram-negative bacteria such as Escherichia coli DH 5-alpha (with plasmid, PUC), Salmonella typhii and Staphylococcus aureus were weakly inhibited. Other microorganisms such as Lactobacillus curvatus D31685, Lactobacillus confusius M23036, Lactococcus lactis MG1363, Leuconostoc paramesenteroides S67831, Pediococcus pentosaceus M58834, Saccharomyces cerevisiae SS553 (wild type) and Escherichia coli JM109 (no plasmid) were not inhibited. [source] Volatile organoselenium monitoring in production and gastric digestion processes of selenized yeast by solid-phase microextraction-multicapillary gas chromatography coupled microwave-induced plasma atomic emission spectrometry,APPLIED ORGANOMETALLIC CHEMISTRY, Issue 12 2004J. Sanz Landaluze Abstract Evolution of volatile organoselenium compounds in the production and gastric digestion of selenized yeast has been monitored. The industrial production of these kinds of material, employed as food supplements, has been simulated in a process of yeast enrichment with inorganic selenium selenium (IV) in different growth media, with variation of the pH value. The in vitro gastric digestion process was carried out with pepsin in an acid and salt mixture. Determination of volatile species of selenium was achieved coupling solid-phase microextraction (SPME) for preconcentration and sample,matrix separation and microwave-induced plasma atomic emission spectrometry, in combination with multicapillary (MC) gas chromatography for separation and detection of the selenium species. The MC column was operated at low temperatures (,30 °C). The method was optimized, using a chemometric approach, with respect to the detection of organoselenium species such as dimethylselenide, diethylselenide and dimethyldiselenide. SPME sampling was carried out in the headspace above the corresponding solutions. Separation is fast, with a chromatogram being obtained in less than 5 min, and the detection limits were at the low parts per billion level for all species investigated. The results of the yeast enrichment process demonstrate inorganic selenium transformation into volatile organic species. The presence of inorganic selenium gave rise to at least five different volatile species after metabolization by yeast, with dimethylselenide and dimethyldiselenide being the predominant species. Commercial pasteurized yeast, containing mainly selenomethionine for use as a food supplement, and tablets were found to be still active under conditions of the simulation of the digestion process, even though producing relatively low amounts of organoselenium compounds. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||