高产洛伐他汀红曲菌的筛选及菌种共酵对红曲固态发酵的影响

本研究以筛选高产洛伐他汀红曲菌,并进一步优化富含洛伐他汀的红曲制曲方法为目的,分离筛选市售红曲中的红曲菌,并进行固态发酵制曲,使用HPLC法对红曲中的洛伐他汀含量进行测定,使用紫外分光光度法检测红曲的色价,选择产洛伐他汀含量最高的菌株进行形态观察和分子生物学鉴定;并进一步将高产菌株与常用食源菌株进行共酵制备红曲,优化洛伐他汀的含量。结果表明,分离筛选得到10株红曲菌,产洛伐他汀最高的菌种是H8-2,经固态发酵14 d后洛伐他汀产量达到9.79 mg/g,色价为1805.43μ/g。菌株H8-2经形态观察和生物学鉴定为紫色红曲菌(Monascus purpureus)。共酵制曲发现除枯草芽孢杆菌外其他菌种均可提高红曲菌产洛伐他汀含量,其中酵母对洛伐他汀产量提高的效果最显著(p<0.01),发酵结束后洛伐他汀含量可达12.37 mg/g。进一步对实验室保藏的多株酵母菌株进行评价,发现酿酒酵母对洛伐他汀产量提高最为明显,共酵后红曲中洛伐他汀含量达到12.93 mg/g,相比未共酵条件下的洛伐他汀产量提高了34.5%。在红曲菌发酵培养基中添加不同酿酒酵母处理液,发现高温灭菌液和酵母破壁液可以使洛伐他汀产量显著提高(p<0.01),分别可达11.96和12.24 mg/g,比对照组提高了24.8%和27.8%。说明酵母的代谢产物对红曲菌发酵产洛伐他汀有一定影响,相关诱导物质可能存在于胞内并且对热不敏感。

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.