牛瘤胃产蛋氨酸热带假丝酵母菌的分离鉴定及发酵条件优化

Isolation and identification of Candida tropical producing methionine from bovine rumen and optimization of fermentation conditions

试验旨在从牛瘤胃微生物中筛选出能够合成并分泌蛋氨酸的菌株。试验以草原红牛瘤胃液为样品,使用蛋氨酸缺陷培养基分离纯化,通过革兰氏染色、游离蛋氨酸含量测定、16S rDNA测序等鉴定菌株。采用单因素设计和正交试验对培养基和发酵条件进行优化,通过体外模拟瘤胃发酵试验测试菌株。结果显示,分离的菌株为热带假丝酵母菌(Candida tropical TYM001)。该菌株最适碳源为20.0 g/L葡萄糖,最适氮源为10.0 g/L无氨基酸酵母,最适无机盐为5.0 g/L NaCl、7.0 g/L MgSO_(4)和5.0 g/L KH_(2)PO_(4)。在最适发酵条件下,游离蛋氨酸含量达到27.815 mg/L。研究表明,该菌株能够提高体外模拟瘤胃总蛋白和游离蛋氨酸含量,为开发反刍动物微生物添加剂提供参考。

The experiment was to screen strains that could synthesize and secrete methionine from bovine rumen microorganisms.The rumen fluid of grassland red cattle was isolated and purified with methionine deficient medium.The strains were identified by Gram staining,determination of free methionine content and 16S rDNA sequencing.The culture medium and fermentation conditions were optimized by single factor design and orthogonal test.The strain was tested by in vitro rumen.The results showed that the isolated strain was Candida tropical TYM001.The optimum carbon source was 20.0 g/L of glucose,the optimum nitrogen sourcewas 10.0 g/L of amino acid free yeast,and the optimum inorganic salts 5.0 g/L of NaCl,7.0 g/L of MgSO_(4) and 5.0 g/L KH_(2)PO_(4).The content of free methionine reached 27.815 mg/L under the best suitable fermentation condition.The experiment indicates that the strain can improve the content of total protein and free methionine in simulated rumen in vitro,providing reference for the development of ruminant microbial additives.