( 2003) reported that the highest bacteriocin production is determined at temperatures and pH lower than that of the optimal cell growth. 2003, 2004 Todorov and Dicks 2009 Todorov et al. Several studies have shown that bacteriocin production is dependent on the biomass (De Vuyst et al. However, bacteriocin production can be influenced by culture conditions, such as incubation atmosphere, pH, temperature and microbial growth phase (Gänzle et al. Usually bacteriocins are produced in complex culture media including MRS, TGE, APT, BHI, TSB and TSBYE (Guerra et al. For instance, nisin is already used as food preservative, and pediocins produced by LAB have bactericidal activity against gram-positive bacteria and are also suitable candidates for use as food bio-preservatives (Bari et al. Many bacteriocins are heat-stable and retain their activity after several months of frozen or refrigerated storage and after drying. LAB bacteriocins have potential biotechnological applications because they are easy to produce, non-toxic to humans, stable at low pH values, and sensitive to proteases (Todorov 2009). Bacteriocins are a group of antimicrobial compounds, which are ribosomally synthesized peptides produced by bacteria to inhibit the growth of similar or closely related bacterial strains either in the same species, or across genera (Bowdish et al. According to Magnusson ( 2003), the antimicrobial effects of LAB contribute to the yield of organic acids, competition for nutrients and production of antagonistic compounds. They are generally recognized as safe bacteria (GRAS status) and play an important role in food and feed fermentation and preservation, either as the natural microflora or as starter cultures under controlled conditions (Daeschel 1989). Lactic acid bacteria (LAB) are a diverse group of gram positive, catalase negative, oxidase negative, and micro-aerophilic organisms (Carr et al. This study provides useful information on potential application of bacteriocinogenic LAB in food fermentation processes. Bacteriocin activity was significantly different in MRS versus BHI ( p < 0.001), and the optimal condition for LAB to produce bacteriocins was determined in MRS broth, pH 6.2 at 37 ☌. LAB growth was significantly affected by the initial pH of culture media ( p < 0.001) and the optimal pH was found ranging from 6.2 to 8.5. Our results indicated that Arla-10, JFR-1, and JFR-5 strains grew well on both MRS and BHI media at growth temperature tested whereas TSB-8 strain, unable to grow at 20 ☌. Growth curves of the bacteriocinogenic LAB were generated using a Bioscreen C. In this study, various growth conditions including culture media (MRS and BHI), initial pH of culture media (4.5, 5.5, 6.2, 7.4 and 8.5), and incubation temperatures (20, 37 and 44 ☌) were investigated for LAB growth measured as optical density (OD), bacteriocin activity determined as arbitrary unit and viability of LAB expressed as log CFU ml −1. The objective of this study was to determine the optimal growth conditions for both LAB growth and bacteriocins production. paracasei (JFR-5) and Streptococcus thermophilus (TSB-8) were previously isolated and identified in our lab. Four bacteriocinogenic lactic acid bacteria (LAB) strains of Lactobacillus curvatus (Arla-10), Enterococcus faecium (JFR-1), Lactobacillus paracasei subsp. There has been continued interest in bacteriocins research from an applied perspective as bacteriocins have potential to be used as natural preservative.
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