Mutation Breeding Selection Of Monacolin K By Monascus Sp. And Study On The Liquid Fermentation

The collected Monascus ssp.were screened,a strain named Monascus ruber GM011 with high productivity of Monacolin K was obtained,whose yield reached to 258.2mg/L.It was used as the original strain,whose spores were treated with ultraviolet,LiCl,ultraviolet-LiCl,HNO₂ and DES.A mutant strain named W₂₈₃was gained,whose yield of Monacolin K increased 53.1%in comparison with the original strain,reached to 395.3mg/L.The production of Monacolin K was stabilized in genetics.Acetic acid,ethyl acetate,ethanol and n-hexane were added in the process of liquid fermentation.The results showed that acetic acid could promote the productivity of Monacolin K by Monascus.The production of Monacolin K was 971.8 mg/L while it was 390.3 mg/L without adding acetic acid,which increased by 149%.It was reduced if it was added more acetic acid in the culture medium.Ethyl acetate,ethanol and n-hexane could affect the productivity of Monacolin K also.Through the productivity of Monacolin K could be promoted by adding a little of MgSO₄,ZnSO₄ in the culture medium,it would be inhibited too more. When ZnSO₄ was 4g/L in the culture medium,W₂₈₃grew abnormally.The high osmotic stress probablely leaded to higher production of Monacolin K.The productivity of Monacolin K could be promoted by adding Job's-tears,and the production could reach to 917.7 mg/L.Response Surface Methodology was applied to optimize the culture conditions for the production of Monacolin K produced by W₂₈₃.In the first optimization step,a Plackett-Burman design was used to evaluate the influence of related factors.Peptone,glycerin and NaNO₃ influenced the production of Monacolin K observably.The maximal production 1290mg/L was obtained under the following conditions(g/L):glucose 20, peptone 16.3,glycerin 95.7,MgSO₄ 1,NaNO₃ 6.8,ZnSO₄ 2,KH₂PO₄ 1, Job's-tears 2.5,KNO₃ 5,initial pH 4.4,8%inoculum.The optimized culture conditions resulted in a 230%increase of the production of Monacolin K,as compared with the original conditions,which was five times as more as the parent strain.