RESUMO
Monascus is a filamentous fungus that produces several secondary metabolites. Here, we investigated the effects of the global regulator LaeA on the synthesis of pigments and monacolin K in Monascus purpureus with spectrophotometer and HPLC methods. The LaeA gene was isolated from M. purpureus M1 to create an overexpression construct. An LaeA-overexpressing strain L3 was with 48.6% higher monacolin K production than the M1 strain. The L3 strain also produced higher Monascus pigments than the M1 strain. SEM showed that LaeA overexpression resulted in altered mycelial morphology. Compared with the M1 strain, the L3 strain expressed higher levels of monacolin K synthesis-related genes mokA, mokB, mokE, and mokH. Overall, these results suggest that LaeA plays a role in regulating the production of secondary metabolites and mycelial growth in Monascus. This study provides important insights into the mechanisms underlying the effects of the LaeA gene on the secondary metabolites of M. purpureus.
Assuntos
Proteínas Fúngicas/genética , Genes Fúngicos , Monascus/metabolismo , Metabolismo Secundário , Fatores de Transcrição/genética , Proteínas Fúngicas/metabolismo , Expressão Gênica , Regulação Fúngica da Expressão Gênica , Lovastatina/biossíntese , Monascus/genética , Monascus/crescimento & desenvolvimento , Micélio/genética , Micélio/crescimento & desenvolvimento , Micélio/metabolismo , Pigmentos Biológicos/biossíntese , Metabolismo Secundário/genética , Fatores de Transcrição/metabolismoRESUMO
Monascus purpureus is a traditional Chinese microbe that can be used as a medicinal herb and is edible. To improve the yield of monacolin K, we optimized the medium of M. purpureus with high-yield monacolin K strains. When high-yield strains C8, D8, E3, and I1 were grown in glutamic medium instead of the original medium, monacolin K production was increased. Among these strains, C8 exhibited the highest monacolin K production in glutamic acid medium, with levels increased 4.80-fold. RT-qPCR demonstrated that glutamic acid enhanced the expression of mokC and mokG. Observation of Monascus mycelium morphology using SEM showed that mycelia exhibited more folds, swelling, curves, and fractures. Thus, glutamic acid may promote the growth of the mycelium and appeared to increase the permeability of the cell membrane. This lays a foundation for research on the regulatory effect of glutamic acid and provides a theoretical basis for the industrialization and commercialization of Monascus.
Assuntos
Ácido Glutâmico/farmacologia , Lovastatina/biossíntese , Monascus/efeitos dos fármacos , Monascus/metabolismo , Meios de Cultura/química , Fermentação , Proteínas Fúngicas/genética , Expressão Gênica , Microbiologia Industrial , Microscopia Eletrônica de Varredura , Micélio/ultraestrutura , Reação em Cadeia da Polimerase em Tempo RealRESUMO
This study investigated the effects of glutamic acid on production of monacolin K and expression of the monacolin K biosynthetic gene cluster. When Monascus M1 was grown in glutamic medium instead of in the original medium, monacolin K production increased from 48.4 to 215.4 mg l-1, monacolin K production increased by 3.5 times. Glutamic acid enhanced monacolin K production by upregulating the expression of mokB-mokI; on day 8, the expression level of mokA tended to decrease by Reverse Transcription-polymerase Chain Reaction. Our findings demonstrated that mokA was not a key gene responsible for the quantity of monacolin K production in the presence of glutamic acid. Observation of Monascus mycelium morphology using Scanning Electron Microscope showed glutamic acid significantly increased the content of Monascus mycelium, altered the permeability of Monascus mycelium, enhanced secretion of monacolin K from the cell, and reduced the monacolin K content in Monascus mycelium, thereby enhancing monacolin K production.
