一株高产Monacolin K紫红曲霉菌株筛选、鉴定及发酵条件优化

为从天然发酵红曲米中分离的30株红曲霉菌株中筛选高产MonacolinK的菌株,并对其产MonacolinK的发酵条件进行优化。实验采用高效液相色谱法(HPLC)筛选到9株具有产MonacolinK能力的红曲霉菌株,其中以编号ZX26的菌株产MonacolinK能力最高,发酵液中Monacolin K产量达到107.6mg/L,并且产MonacolinK能力具有良好的稳定性。微生物形态学结合ITS基因同源性分析结果表明,编号ZX26菌株为紫红曲霉。进一步采用单因素试验和正交试验法优化紫红曲霉ZX26产MonacolinK的发酵条件,结果表明在培养基组分为葡萄糖70g/L,牛肉膏15g/L,NaNO32g/L,MgSO4·7H2O0.5g/L,KH2PO41.5g/L时,其最优发酵条件为:发酵初始pH4.0,接种量为7%,培养温度30℃,发酵10天,在此条件下,紫红曲霉ZX26发酵液中MonacolinK产量达到271.36mg/L,相对于培养条件优化前MonacolinK产量提高152.19%,经验证此培养条件下MonacolinK产量最佳。

Screening,identification and fermentation condition optimization of a high Monacolin K producing Monascus purpureus

The purpose of this study was to screen the high Monacolin K-producing strains from30 strains of Monascus Strain separated from natural fermented red yeast rice,and further to optimize the fermentation conditions of Monacolin K.The results showed that 9 strains of Monascus were found to produce Monacolin K by high performance liquid chromatography (HPLC) analysis.The strain No.ZX26 was the strongest strain in producing Monacolin K,and the yield of Monacolin K in the fermentation broth reached up to107.6 mg/L.The ITS gene homology analysis showed that Monascus Strain ZX26 was Monascus purpureus. The single factor test and orthogonal test method were used to optimize the fermentation conditions of Monacolin K produced by Monascus purpureus ZX26 further.The results showed that,when the composition of the medium was glucose 70 g/L,beef extract15 g/L,NaNO32 g/L,MgSO 4·7H2O 0.5 g/L and KH2PO 41.5 g/L,the optimal fermentation conditions including the initial pH of 4.0,culture temperature of30 ℃,inoculum size of 7% and fermentation time of10 days were determined.On the optimal fermentation conditions,the yield of Monacolin K reached up to271.36mg/L,which increased by152.19% compared with the production of Monacolin K before optimizing fermentation conditions,It was proved that the Monacolin K yield was the best under this cultivation condition.