Optimization of fermentation condition for Bacillus natto

The single-factor and orthogonal experiment was used to optimize the medium of Bacillus natto. The optimal medium is as follows: sucrose 15 g/L, yeast extract 2.5 g/L, pancreatic peptone 2.5 g/L, NaCl 5 g/L. The optimal fermentation conditions investigated through single-factor test are as follows:temperature 35 ℃, initial pH8.0, inoculation amount 3%, liquid volume 20 mL/250 mL, fermentation time 14 h.