Blue Light Effects on Pigment and Citrinin Production in Monascus

In order to obtain high quantity and quality of pigment, we investigated the blue light effects on pigment and citrinin production of Monascus in submerged fermentation. Our study showed that at the 6th day of the fermentation, the pigment production enhanced 28.5% upon blue light illumination whereas the citrinin content decreased 79.0% when comparing with that in dark. The degradation effects of blue light on pigment and citrinin were also investigated. The degradation of pigment and citrinin were followed a first-order reaction kinetics. The half lives of citrinin and pigment were 4.7% and 47% of those under the darkness, respectively. Although the pigment was unstable under blue light illumination, the production of pigment still increased dramatically, which further implied that the blue light, maybe as a signal factor, stimulated the pigment accumulation. Higher degradation rate upon blue light seems to be the dominant factor that contributed to the lower citrinin content obtained from blue light assisted fermentation.