Fermentation conditions of lactobacilli for the production of lactose-free starter culture

Abstract

Abstract A total of 16 strains of Lactobacilli were isolated from traditional Kazakh homemade dairy products. The strains identified by 16sRNA sequencing. The aim of this study was to evaluate probiotic properties of Lactic acid bacteria (LAB) Lactobacillus acidophilus (Lb. acidophilus) and Lactobacillus rhamnosus (Lb. rhamnosus) cultures were chosen as starter probiotic strains. Tested strains were had strong inhibitory effect against Gram-negative pathogens: Salmonella typhimurium (S. typhimurium), Serratia marcescens (S. marcescens) and Escherichia coli (E. coli). We evaluated the tolerance to various pH values (3.0, 4.0, 5.0, 6.4, 8.5), survivability in different salt concentrations (2%, 5%, 7%). All isolates survived at pH 3.0–4.0, 5–7% NaCl. The pasteurized milk (PM) was inoculated with two starters lactic acid bacteria performed for 24 h at 37°C. Lb. acidophilus and Lb. rhamnosus starter culture reached cell population of about ~ 8 logs colony forming unit (CFU/mL) during co-culture fermentation, pH in pasteurized milk rapidly decreased to 3.0.