Non-growth associated production of enzymes in solid state fermentation system: Its mathematical description for two enzymes produced by Bacillus licheniformis M27

Logistic model, based on more general and realistic assumptions, has been derived to express the production of two non-growth associated enzymes by Bacillus licheniformis M27 in a solid state fermentation system. The model explained the production of alpha-amylase and neutral protease with correlation coefficients ranging between 0.974 and 0.985 in basal and standardized wheat bran media. It is apparent from the values of parameters in the model that the rate constant in standardized medium was lower (0.15 l/h−1) than in the basal medium (0.32 l/h−1), though higher maximum enzyme titres (1.7 times) were observed in the former medium. The data thus indicate dependence of enzyme titres on the maximum biomass formed. The model represents a significant advance in model formulation as it recognizes and takes care of all other products (enzymes etc) formed during fermentation. The model may prove useful in optimizing product synthesis, design of bioreactor and determination of harvest time, especially due to its adequacy and efficiency. Models for predicting product formation in solid state fermentation system are scarce and confined to fungal fermentations. No such model for bacterial solid state fermentation system was available earlier.