Study on solid-state fermentation of pig bone extract by single and double Aspergillus

Pig bone extract as the main raw material, the change of protease activity, amylase activity, xylanase activity, amino acid nitrogen, reducing sugar and red index were investigated during solid-state fermentation by Monascus and double strains of Monascus and Aspergillus oryzae. At the same time, the protein degradation products were analyzed by SDS-PAGE electrophoresis. The results showed that in the process of Monascus fermentation, enzyme activities increased to its peak and then decreased. Neutral、alkaline protease and xylanase activities evidently increased with double strains fermentation (inoculating Aspergillus oryzae after Monascus had fermented for 10 days) , while there were not significant changes in acid protease and amylase activities compared to Monascus fermentation. Furthermore, production of Amino acid nitrogen and consumption of reducing sugar with double strains fermentation were higher than that with Monascus fermentation. SDS-PAGE showed that compared with Monascus fermentation, double strains fermentation showed more polypeptide bands and wider range of molecular weight, which indicated double strains fermentation had the high degree of protein degradation.