Abstract: This work aims to increase the total spores of Bacillus amyloliquefaciens M1 in fermentation,and investigate the anaerobic denitrification effect in wastewater. First,single factor experiments were used to investigate the effects of species and concentrations of various carbon and nitrogen sources,initial pH,temperature,shaking speed,medium volume etc. on the spore yield of M1.Then orthogonal experiments were carried out to optimize 4 significant factors of nitrogen source concentration,inoculation amount,liquid loading amount and temperature. Results showed that the optimal composition of the medium were as such：5 g/L carbon source（soluble starch）,10 g/L nitrogen source[yeast powder and tryptone mix（2∶1,V/V）],1 g/L NaCl. The optimal cultural condition was as：initial pH6.5,temperature 34℃,shaking speed 180 r/min,medium capacity 30%（75 mL/250mL）,and inoculation rate 7%. Under the optimal fermentation condition,the total spores yield of B. amyloliquefaciens M1 was up to 6.8×10⁸ CFU/mL,2.3 times higher than that cultured in LB medium（2.08×10⁸ CFU/mL）. Compared with the control test,test with M1 addition showed 15%-34% higher denitrification.

Key words: Bacillus amyloliquefaciens, liquid fermentation, sporulation rate, orthogonal experiment, nitrogen removal by anaerobic denitrification·