Abstract:Geobacillus galactosidasius is a common bacterial group in the livestock and poultry waste composting fermentation process, and plays an important role in aerobic composting fermentation. To obtain the optimal liquid fermentation conditions for strain BWTGW1-1 and establish its large-scale production process, a single factor and response surface methodology were used to optimize the composition and fermentation conditions of the liquid fermentation of strain BWTGW1-1. The results showed that the optimal medium composition and conditions for liquid fermentation of strain BWTGW1-1 were as follows: mannitol (2.50 g/L), yeast extract (8 g/L), soy peptone (5 g/L), sodium chloride (1.50%), culture temperature of 60 ℃, pH value 6.00, and liquid inoculum (0.50%). Under these conditions, the OD600 nm value of the liquid inoculum of strain BWTGW1-1 reached 1.423 7. On this basis, using a 5 ton liquid fermentation tank system, a largescale liquid fermentation process for strain BWTGW1-1 was established, and validated through two batches of large-scale production. Nearly 5.50 tons of strain BWTGW1-1 liquid microbial product were obtained, with an effective viable bacterial count of 7.25×108 CFU/mL. The effective viable count in the spray-dried raw powder reached 1.12×1010 CFU/g, with a noticeably low impurity rate (<0.01%). Conclusively, the optimal pilot production fermentation conditions for strain BWTGW1-1 were as follows: mannitol 2.50 g/L, yeast extract 8 g/L, soy peptone 5 g/L, NaCl 1.50 wt.%, pH 6.00, temperature 60 ℃, fermentation speed 150 r/min for 0~12 h, 250 r/min for 12~24 h, ventilation rate 20 m3/h, and fermentation time of 24 h.
