Monacolin K is a secondary metabolite of Monascus and is known to decrease cholesterol levels in humans. There are 9 genes (mokA-mokI) controlling its biosynthesis, of which mokH is thought to act as a pathway-specific regulator. In this study, the Monascus purpureus M1 strain was compared with mokH gene deletion strains (△H1) and overexpression strains (H7). The monacolin K yields in the △H1 strain were reduced by 52.05 %, and increased in the H7 strain by 82 %. The mycelium samples of the M1, △H1, and H7 strains were found to vary with scanning electron microscopy. Compared to the M1 strain, some mycelium of the △H1 strain showed obvious folding and expansion, while the mycelium of the H7 strain was fuller. Besides, these results indicate that the mokH gene can increase the yield of monacolin K by regulating the expression level of mokA-mokI genes, and influence the production of Monascus pigment. The study is the first to combine deletion and overexpression techniques to further verify the mokH gene and get the desired results in M. purpureus.

中文翻译：

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mokH基因缺失和过表达对紫红曲霉孢子形成和次生代谢产量的影响

Monacolin K 是红曲霉的次生代谢产物，已知可降低人体胆固醇水平。有 9 个基因 (mokA-mokI) 控制其生物合成，其中 mokH 被认为是通路特异性调节剂。本研究将红曲霉M1菌株与mokH基因缺失菌株（△H1）和过表达菌株（H7）进行比较。△H1 菌株的莫纳可林 K 产量降低了 52.05%，而 H7 菌株的产量增加了 82%。发现 M1、△H1 和 H7 菌株的菌丝体样品随扫描电子显微镜而变化。与M1菌株相比，△H1菌株的部分菌丝体表现出明显的折叠和扩张，而H7菌株的菌丝体更饱满。此外，这些结果表明，mokH基因可以通过调节mokA-mokI基因的表达水平来提高monacolin K的产量，并影响红曲霉色素的产生。该研究首次结合删除和过表达技术进一步验证了mokH基因，并在紫癜中获得了预期的结果。