Modelling of simultaneous effect of moisture and temperature on A-niger growth in solid-state fermentation

In the present work a two factorial design of experiments was applied to study the simultaneous effect of temperature and moisture on A. niger growth in the solid-state fermentation (SSF). The increase of water content to more than 55% at the temperatures 35 and 40degreesC decreases microorganism growth. The logistic model was used to calculate growth kinetic parameters at different levels of temperature and moisture in solid-state fermentation. Ratkowsky equation was used to express the effect of temperature on specific growth rate. Quadratic polynomials express relationship between moisture content and growth parameters (maximum biomass and maximum specific growth rate) of A. niger inoculated on steamed wheat bran. The highest value of mu(m) and X-m were 0.29 h(-1) and 0.22 g biomass g DW-1 at 35degreesC and 55%, respectively. (C) 2004 Elsevier B.V. All rights reserved.