高产蛋氨酸内生菌的筛选、诱变及发酵条件优化

Screening,mutagenesis breeding,and optimization of fermentation conditions of high-producing methionine endophytes

为筛选出蛋氨酸高产菌株,该研究对富含蛋氨酸的盐肤木种子中的内生菌进行挖掘。对筛选出的蛋氨酸产量较高的内生菌进行筛选、鉴定,并利用蛋氨酸结构类似物和^(60)Co-γ射线诱变进一步筛选。随后通过响应面试验,探究葡萄糖添加量、硫酸钠添加量和法尼醇添加量对该菌株蛋氨酸产量的影响。结果表明,筛选得到的产蛋氨酸的菌株LB-2,使用16S rRNA序列分析并结合形态学观察,鉴定其为微球菌。随后,经过诱变筛选得到高产蛋氨酸的菌株LB-2-13。通过单因素和响应面法优化,在葡萄糖14.70 g/L,硫酸钠0.98 g/L,法尼醇96.35μmol/L的培养条件下,发酵液中蛋氨酸的产量最高,可以达到2.85 g/L,产量提高了约88%。该研究首次使用植物内生菌作为原始菌株,利用蛋氨酸结构类似物和^(60)Co-γ射线诱变筛选高产蛋氨酸菌株,可为微生物发酵法实现蛋氨酸的工业生产提供技术支持。

In this study,the endophytes in methionine-rich Rhus chinensis seeds were screened for high methionine producing strains.The methionine producing endophytes were screened,identified,and further bred with methionine analogs and ^(60)Co-γ-ray mutagenesis.Subsequently,response surface methodology was used to investigate the effects of glucose,sodium sulfate and farnesol on methionine production of the strains.Results showed that the strain LB-2 with high methionine yield was identified as micrococcus by 16S rRNA sequence analysis and morphological identification.Subsequently,the strain LB-2-13 with higher methionine yield was obtained by mutagenesis breeding.The highest yield of methionine in the fermentation broth could be achieved at 2.85 g/L under the incubation conditions of 14.70 g/L glucose,0.98 g/L sodium sulfate,and 96.35μmol/L farnesol by single-factor and response surface method optimization,which increased the yield by about 88%.In this study,plant endophytes were used as the original strains to screen high methionine yielding strains for the first time.Furthermore,high-producing methionine strains were effectively bred with methionine analogs and ^(60)Coγ-ray mutagenesis.This study could provide technical support for the industrial production of methionine by microbial fermentation.