Optimization of monascus red pigment fermentation by regulating chitinase activity level in fermentor

Abstract

Enhancement of monascus pigment production in a co-culture of Monascus sp. J101 with Saccharomyces cerevisiae was accomplished using chitinase in the feeding of a S. cerevisiae culture filtrate. Batch fermentations were carried out at constant chitinase activity levels of 0.8 U and 0.5 U after 24 h of cultivation. Monascus red pigment concentrations obtained at the end of fermentation were 182.4 OD units and 147.3 OD units, respectively, for chitinase activity levels of 0.8 U and 0.5 U. The cell mass was higher at 0.8 U than at 0.5 U, whereas pigment production per unit cell mass was higher at 0.5 U than at 0.8 U. Kinetic equations involving cell growth rate, cell activity and chitinase activity levels were analyzed. Cell activity was expressed as a function of mean cell age. The optimum time for reduction of the chitinase activity level from 0.8 U to 0.5 U for maximization of monascus pigment production was numerically estimated to be 60 h. Based on this result, a batch fermentation was performed where the chitinase activity level was maintained at 0.8 U from 24 h to 60 h, then the level was lowered to 0.5 U after 60 h. This scheme resulted in a monascus pigment production of 198.3 OD units.