Abstract:

【Objective】 An optimization of parameters in solid-state fermentation of rapeseed meal by mixture of two protease-producing bacterial strains Stenotrophomonas maltrophilia G12 ( FJ211222) and Bacillus pumilus K11 (FJ211221) for an amino acid fertilizer was studied to provide a theoretical basis in the industrial production. 【Method】 The fermentation processes were optimized by using of Response Surface Methodology (RSM) with Plackett-Burman Experiments and Box-Behnken Design. Data were analyzed with Design-Expert 7.0 software and Mintab 15.0 software. 【Result】 High amino acid production in fermentation processes was observed under the optimized condtions: 6 days of fermenting, 54.5% of initial moisture, initial pH value at 9.15, 14.1% of wheat bran supplementation, 5% of mixed inocula in equal volume, and one time of ventilation in 24 hours. 【Conclusion】 Under the optimized fermentation conditions, the degree of hydrolysis of rapeseed meal protein reached 13.1% with high contents of free amino acids and small peptides.

Key words: amino acid fertilizer, solid-state fermentation, response surface methodology, degree of hydrolyzation