High-density culture and metabolite analysis of Bacillus licheniformis HR
The aim of this experiment was to optimize the culture medium of Bacillus licheniformis and determine its optimal culture conditions,providing the basis for industrialization.With the number of viable bacteria and OD650nm as the detection indexes,the medium and culture conditions were optimized and expanded to the size of 50 L tank.GC-MS was used to detect and analyze the volatile substances in the culture medium.The results showed that the optimum conditions for Bacillus licheniformis culture were α-lactose 2 g/L,soybean meal 20 g/L,MnSO4 1 g/L,FeSO4 0.01 g/L,MgSO4 0.04 g/L,K2HPO4 2 g/L,4%inoculation amount,24 h incubation time,initial pH 7.The maximum number of viable bacteria cultured in 50 L fermenter was 1.36× 109 CFU/mL.A total of 12 substances were detected by GC-MS,among which 3,5-dimethyl-1,3,4-hexyl alcohol,L-lactic isobutyric acid and 2-methylbutyric acid had different degrees of prebiotic effects on animal body.The optimized conditions were used for HR culture of Bacillus licheniformis,and the number of viable bacteria in the culture medium was increased,thus improving its production efficiency and having certain practical significance for its industrialization.