Study On Regulation Of Envitonmental Factors To Citrinin Production In Monascus

Monascus spp. is an important microbic resource in China, but its metabolism of the mycotoxin citrinin limits the development of red yeast products. In this paper, Monascus15-1was chose for the following studies. We studied the effect of environmental factors on growth and citrinin content in M.15-1. Meanwhile, the citrinin degradation mechanisms both in vivo and in vitro were discussed, as well. The major findings are as follows.By the liquid fermentation, the author studied the effect of temperature on the production of citrinin in Monascus15-1, the data showed that low temperature (27℃) could stimulate the synthesis value of citrinin. Using static cultivation, the citrinin content under27℃was1.679-fold more than that under37℃. High dissolved oxygen reduced the amount of citrinin accumulation, the citrinin peak value in this condition, was equals to1/3.6-fold-time of the value under static culture.At the morphological study, results showed that the color of Monascus15-1in blue light group was gray, which is lighter than the control group (tawny yellow). Conidiophores observed in mycelia at the tips of colonies under blue light were shorter and the growth was tighter, compared to colonies grown in the dark.Blue light had an impact on the formation pace of citrinin, induced the citrinin peak value was1d later than the control group. Under27℃, there was no significant difference in the citrinin peak value between blue light group and dark control group. However, under37℃, the peak value of citrinin in blue light group was987.908±98.979μg/mL, its1.524times more than the control group. What’s more, this phenomenon occurred in the biofilm illumination-test and spores suspension-test, as well. In addition, M.15-1could sense the white light signal, raised the amount of citrinin formation, but the white light had no impact on the growth of mycelium.The effect of blue light on sporulation had been studied, the results showed that blue light can stimulate the formation of sexual spores, but it inhibited the germination and the formation of asexual spores. Through the fluorescence microscopy images of conidia and asci spores in Monascus15-1, we found that both conidia and asci could be observed the fluorescent layer around the cell walls. The test obtained the preliminary assessment, both conidia and asci were related with the citrinin production.Meanwhile, citrinin degradation mechanism was discussed:in vitro, blue light illumination had a strong photodegradation to citrinin; in vivo, blue light could stimulate the synthesis of catalase, thereby reducing the effect of H2O2on citrinin degradation.