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  • Influence of pH on bacteriocin production by Lactobacillus K7 during batch fermentation
    Bogovič Matijašić, Bojana ...
    Production of bacteriocins - antimicrobial proteins by lactic acid bacteria (LAB) is higly affected by growth medium composition, temperature, pH and other factors. For purification purposes or for ... their use as biopreservatives,it is necessary to determine the optimal growth conditions for their production. In previous studies, Lactobacillus K7 strain was found to produce bacteriocins with a wide range of activity. Influence of pH on growth and bacteriocin production by Lactobacillus K7 probiotic strain was studied during batch fermentation in bioreactor. Fermentations were performed in BIA/Chemap bioreactor with automatic pH regulation. Volume of 2500 ml of MRS broth was inoculated (2%) with Lactobacillus K7 culture incubated for 18 h in MRS broth at 370oC. The growth was followed by measurement of optical density and estimation of cell dry weight. Bacteriocin concentration in the supernant was determined by critical dilution essay on microtiter plates, using L. sake NCDO 2714. The on-line measurement of glucose and lactic acid were performed by HPLC every hour. CFU/ml was determined by plating on MRS agar. pH strongly affected bacteriocin production, growth and lactic acid accumulation by Lactobacillus K7. Bacteriocins were produced during the exponential phase of growth. The highest specific growth rate and CFU/ml were achieved at pH=7, hovewer low bacteriocin concentration was determined. On the contrary, the highest concentration of bacteriocins and their specific activity were determined at pH=6, although the growth of bacteria was not optimal. Furthermore no direct correlation among lactic acid and bacteriocin production was found, and glucose was not a limiting factor. The regulated pH value of 6.0 was found to be the most suitable for bacteriocin production.
    Vir: Periodicum biologorum : an interdisciplinary international journal of the Societas Scientiarum Naturalium Croatica established 1885. - ISSN 0031-5362 (Vol. 103, št. 2, 2001, str. 163-167)
    Vrsta gradiva - članek, sestavni del
    Leto - 2001
    Jezik - angleški
    COBISS.SI-ID - 1175432

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