Abstract:

This research aims to establish a theoretical foundation for the production, application, and further exploration of Bacillus licheniformis and its liquid formulations by studying the liquid culture medium of Bacillus licheniformis and the preservation methods of its liquid preparations. Using Bacillus licheniformis as the test material, the liquid culture medium was optimized by orthogonal test, and the optimal medium was verified by fermenter test; different proportions of Lactobacillus plantarum were added to its liquid preparation to determine the best preservation method. The results were as follows. (1) The optimal medium and fermentation conditions were as following: bran 10 g/L, soybean meal 15 g/L, calcium carbonate 0.75 g/L, sodium chloride 10 g/L. The initial pH was 7.5, the temperature was 37℃, and the viable count of effective bacteria in the fermentation broth attained 2.68×10¹⁰ cfu/mL. The fermentation in a 2 t fermenter was completed after approximately 24 hours of cultivation, achieving a viable count of 3.8×10¹⁰ cfu/mL. (2) At indoor temperature, in the experimental groups supplemented with 2.00% and 5.00% Lactobacillus plantarum, the survival rates of Bacillus licheniformis were 84.2% and 84.1%, respectively, after 30 days, and reached 54.3% and 52.4% after 90 days. This study obtained a high-density liquid fermentation medium for this strain of Bacillus licheniformis, and laid a theoretical foundation for the research on the preservation of Bacillus licheniformis liquid preparations.

Key words: Bacillus licheniformis, fermentation medium, liquid preparations, effective viable bacteria count, spore rate, bran, Lactobacillus plantarum