Microbial rennet produced by Mucor miehei in solid-state and submerged fermentation

Abstract

The aim of this work was to study the effect of carbon and nitrogen sources in submerged fermentation, and the casein effect on solid-state fermentation on rennin production by Mucor miehei. Biomass peaks reached 6.7; 8.1 and 8 g/L and enzymatic production peaks of 1,066; 857 and 480 Soxhlet Units (S.U.) for glucose concentration of 18; 25 and 35 g/L respectively. Flasks with baffles showed biomass peaks of 6.7; 8.3 and 10 g/L and enzyme activity peaks of 648; 279 and 300 S.U. for the same glucose concentration. The values of 923 and 667 S.U. were obtained when corn steep liquor and Proflo (Cottonseed Nutrients from Traders ®) were used. In SSF system the enzymatic activities were 414, 264 and 167 S.U., when using HCl 0.2 N, 0.3 N and 0.4 N respectively. SSF experiments using 1 and 2 g of casein/gram wheat bran (10% moisture) showed an increase in the enzymatic production (966 and 1,117 S.U.). The results suggested that increase in glucose concentration affected the enzyme synthesis, and casein was the prime factor in the enzyme synthesis induction. SSF showed to be a good system for rennin production.