Isolation and optimization on spore-forming conditions of Bacillus coagulans

Abstract:

[Background] In addition to the general function of lactic acid bacteria, Bacillus coagulans have strong biological properties of resistance to acid, bile salts, heat and easy storage. [Objective] Screen a strain of Bacillus coagulans from pickle to apply for the preparation of probiotics and optimize its sporulation rate as a guide for further industrial production. [Methods] Bacillus with good antibacterial effect screened by specific culture conditions, are identified by specific primers, 16S rRNA gene sequence analysis and physiological & biochemical experiments. The single-factor and orthogonal experiments are used to optimize the spore-producing conditions. [Results] Bacillus coagulans BC01 with a strong inhibitory effect to Escherichia coli CVCC 1527, Salmonella typhimurium CVCC 2228, Clostridium perfringens CVCC 46 and Salmonella choleraesuis CVCC 503 was screened. Its survival rate under 120 min of gastric acid treatment is up to 94%. 84.3% after 6 h in the 0.3% bile salt solution. The best medium is obtained by single factor and orthogonal experiment optimization. The optimized formula includes, molasses 10.0 g/L, yeast leaching powder 20.0 g/L, NaCl 5.0 g/L, K2HPO4 5.0 g/L and MnSO4 10.0 mg/L. The optimum culture conditions are as follows, inoculation quantity 4%, temperature 45 °C, initial pH 7.0, rotational speed 200 r/min, culture time 36 h. Under the conditions, the number of viable cells up to 6.7×109 CFU/mL and the rate of sporulation 89.2%. [Conclusion] Bacillus coagulans BC01 for microecological preparation was screened. The sporulation rate of Bacillus coagulans BC01 was optimized. It will lay down a foundation for industrial scale production of Bacillus coagulans.