可改良棉粕蛋白的菌株选育及其发酵

棉粕蛋白质含量高达38％~50％,然而作为饲料其蛋白质品质较差,饲料利用率较低。为提高其蛋白质利用率,从自然界筛选出了能够高效降解棉粕大分子蛋白质的优良菌株4株,经生化与分子生物学试验鉴定为Bacillus subtilis(2株,编号为H1和H7),Bacillus cereus (1株,编号为H9)和Aspergillus niger (1株,编号为P1)。通过单菌及组合发酵实验比较发现:最适宜菌种组合为B. subtilis(H1)和A. niger (P1)。两菌株组合发酵后,棉粕TCA-NSI(三氯乙酸氮溶指数)提高了25.34%,小分子多肽含量提高了11%,游离必需氨基酸提高了24%,蛋白质的体外消化率由44.56%提高到了78.61%,明显高于其他菌种组合,研究结果表明其组合发酵可有效改良棉粕蛋白品质,显著提高棉粕蛋白的饲用价值。

Screening of Strains and Fermentation for Improving the Properties of Cottonseed Meal Protein

The content of protein is usually 38%~50% in the cottonseed meal. However, some properties of the protein make cottonseed meal unsatisfiable for the animal feed industry. To solve the problem, four predominant strains, which can efficiently degrade the macromolecular protein of cottonseed meal, were isolated from natural samples. Based on biochemical characteristic and molecular biology identification, they could be classified as B. subtilis (2 strains, marked as H1 and H7), B. cereus (1 strain, marked as H9) and A. niger (1 strain, marked as P1). Either individual strain or combined strains fermentations were carried out. The results showed that under the optimal strain combination (B. subtilis H1 and A. niger P1) fermentation of cottonseed meal, the content of acid-soluble protein increased by 25.34%, the content of small peptides increased by 11% and the content of the total soluble amino acid increased by 24%, meanwhile, the digestibility of protein increased from 44.56% to 78.61%, which were significantly higher than other strains combination. The results showed that the fermentation by strains combination (B. subtilis H1 and A. niger P1) can improve the forage utilization ratio of the cottonseed-meal-protein effectively.