蛋白饲料酵母高产菌株的选育及发酵工艺优化研究

饲料中的蛋白含量，是衡量饲料优劣的主要指标，而决定饲料蛋白含量高低的主要因素包括：菌体蛋白含量(酵母菌、乳酸菌等)及饲草中自身蛋白含量；其中饲料酵母菌株蛋白含量直接决定了饲料蛋白的含量，因此获得优良的饲料酵母菌株成为关键。本研究利用辐射能量为80 MeV/u的¹²C⁶⁺重离子束对出发饲料酵母菌种NJ3236 (蛋白质量分数为40.64%)进行辐照诱变，并对辐照后的菌种进行初筛、复筛得到高蛋白含量菌株100G-2，该菌株较NJ3236蛋白含量提高了10.08%。利用响应面分析法对发酵培养基进行优化，通过优化得到的培养基的最优配比为：甜高粱汁20.95 g/L、玉米浆干粉18.17 g/L、硫酸镁1.60 g/L，在此条件下可溶性蛋白浓度达到1.381 mg/mL，较未优化前可溶性蛋白提高了8.7%。

Screening and Breeding of High Yield Strain of Protein Feed Yeast and Optimization of Its Fermentation Process

Protein content in feed is a key index for evaluating feed quality, However, recent reports of determine the protein content of feed on dietary for feeds tuffs investigated as potential sources of protein content (yeast, lactic acid bacteria, etc.) and protein content of the forage. The protein content of feed yeast strains directly determines the protein content of feed, so it becomes the key to obtain good feed yeast strains. In this study, a heavy ion 12C6+ beam with an energy of 80 MeV/u was used for irradiation mutagenesis and breeding of starter yeast NJ3236(protein content of 40.64%), and the strains were screened and rescreened to obtain 100G-2 strain with high protein content. The protein content of the 100G-2 strain increased by 10.08% compared with that of the strain NJ3236. Then response surface analysis was used to optimize the fermentation medium. The optimal ratio of medium showed that sweet sorghum juice 20.95 g/L, corn steep liquor 18.17 g/L and magnesium sulfate 1.60 g/L. Under this condition, the soluble protein concentration reached 1.381 mg/mL, which was 8.7% higher than that before optimization.