Screening of Monascus with High-yield Lovastatin and Effects of Co-fermentation on Solid-state Fermentation

The commercially available hongqu was as raw material to screen the Monascus with high-yield lovastatin and further improving the method of making lovastatin-rich hongqu. Monascus strains were isolated and screened from commericial hongqu and fermented by solid state fermentation,the lovastatin in hongqu was determined by HPLC. The color value of hongqu was detected by ultraviolet spectrophotometry. The strain with the highest content of lovastatin was selected for morphological observation and molecular biological identification. Futhermore,high-yielding strains were co-fermented with common food-source strains,and the content of lovastatin was optimized. The results showed that 10 strains of Monascus were isolated. The most powerful capability of producing lovastatin named H8-2 was verified to have a lovastatin yield of 9.79 mg/g and a pigment value of 1805.43 μ/g on solid-state fermentation for 14 d. The Monascus strain H8-2 was identified as Monascus purpureus by morphological observation and molecular biology identification. Most of the strains had beneficial effects on the yield of lovastatin except Bacillus subtilis. Yeast had the most obvious effect on the increase of lovastatin production. The lovastatin content reached 12.37 mg/g after the end of fermentation. By evaluating the effects of different yeast strains,it was found that S. cerevisiae had the greatest effect on lovastatin,and the lovastatin yield was 12.93 mg/g,which was 34.5% higher than the control. Adding different S.cerevisiae treated liquid to the fermentation medium of Monascus,it was found that the high temperature sterilizing liquid and the breaking yeast liquid could make the yield of lovastatin increase significantly. The lovastatin production significantly increased to 11.96 and 12.24 mg/g,respectively,which was 24.8% and 27.8% higher than the control group. This result suggested that metabolites in yeast might had certain effects on lovastatin production by Monascus fermentation,and related inducers might be intracellular and not sensitive to heat.