CRITICAL IMPORTANCE OF MOISTURE-CONTENT OF THE MEDIUM IN ALPHA-AMYLASE PRODUCTION BY BACILLUS-LICHENIFORMIS M27 IN A SOLID-STATE FERMENTATION SYSTEM

A large reduction (about 30%-78%) is observed in the production of alpha-amylase by Bacillus licheniformis M27 in standardized wheat bran medium under solid-state fermentation when the moisture content of the medium is higher than the standardized value (65%). However, a surge in enzyme production in the first 24 h of fermentation is observed in media with 75% and 85% moisture. The role of decreased oxygen transfer in reducing enzyme tires by about 78% in the medium containing 95% moisture is evident, since the enzyme tire can be effectively increased by agitating the medium during fermentation. No such limitation in oxygen transfer is evident in medium containing 65% moisture even where incubated under static conditions or when the flask is capped by aluminum foil. The data indicate the critical importance of the moisture content of the medium in α-amylase production by B. licheniformis M27 in solid-state fermentation systems. The results also have several implications of scientific and techno-economic importance and are useful in explaining some of the advantages of a solid-state fermentation system over the submerged fermentation process. © 1990 Springer-Verlag.