| In order to increase the number of effective bacteria of Bacillus megaterium ZS-3 and reduce the fermentation cost of ZS-3, combination of single factor, orthogonal, and response surface method were used to investigate the fermentation conditions to produce the highest number of viable ZS-3, including carbon source, nitrogen source, inorganic salt, rotation speed, liquid filling volume, pH, temperature, inoculation volume, and other culture conditions. The results showed that strain ZS-3 optimal carbon, nitrogen source and inorganic salt were soluble starch 1.0% (mass fraction), corn milk dry powder 0.5%, diammonium hydrogen phosphate 0.5%, aluminum potassium sulfate dodecahydrate 0.5%; optimal cultivation conditions were rotation speed of 200 r/min, liquid filling volume 40%, pH of 6.67, 30.37 ℃, and inoculation volume 1.31% (v/v), the biomass reached the highest. After optimization, the number of cultured cells reached 1.21 × 109 cfu/mL， the number of viable cells in ZS-3 is 3.9 times those of the viable cells produced under the original cultivation conditions. The fermentation cost reduced and provided theoretical basis and data support for the possible industrial expansion of fermentation production in the future. |
