SUBSTRATE PARTICLE-SIZE REDUCTION BY BACILLUS-COAGULANS IN SOLID-STATE FERMENTATION

Experiments were undertaken to study the mechanism of solid particle d egradation by Bacillus coagulans NK1 in solid-state fermentation (SSF) . The particle size reduction during the course of the fermentation an d its corresponding effect (which indicates the substrate availability ) on the production of enzymes was analyzed. The physical changes, suc h as water-holding capacity and moisture level, were analyzed at diffe rent time intervals during the course of the fermentation. The organis m preferentially utilized the smaller particles having higher starch c ontent throughout the course of the fermentation. The degradation was followed on larger particles toward the end of the fermentation. Maxim um reduction in size as well as total weight of the substrate particle and optimal release of the major hydrolytic enzymes, such as alpha-am ylase and xylanase, were observed around 36-48 hours of fermentation. A mathematical model has been proposed for the substrate particle size degradation during fermentation based on the heterogeneous noncatalyt ic reactions of chemical engineering.