Background: Soybean meal was used as substrate to evaluate effects of three microorganisms, Bacillus sublitis (B), Saccharomyces sp. (S) and Lactococcus lactis (L), on peptide production by solid-state fermentation (SSF) with a shorter fermentation time (such as 36h or less), and the corresponding mechanism, under the condition of liquid soybean meal dextrose medium as culture medium and soybean meal as solid substrate without other supplements, thus forming a environment of limited living condition, enhance microbial competition. Results: Some synergistic effects and appropriate inoculation ratio of starter culture were found to increase peptide yield and protease activity, reduce the pH of system to acidity and shorten the fermentation time to 36h or less in soybean meal SSF. The highest peptide content was achieved at the inoculation ratio of 2:1:1 of microorganism combination of B+S+L, also with the highest protease activity and quick growth characteristics of these three microorganisms, indicating that the peptide production was associated with the protease activity and various microbial growths. Conclusions: So appropriate inoculation ratio of starter culture speeded up the SSF of soybean meal and the mechanism of microorganism improvement of peptide production in SSF of soybean meal could be inferred reasonably, demonstrating the potential for the high peptide production of soybean meal SSF in the industry.
