为筛选出与乳酸菌混合发酵豆粕效果较佳的菌株,以透明圈法分别从霉豆腐、发酵豆粕、酱油发酵原液等样品中初筛得到13株产蛋白酶菌株,经过复筛固态发酵豆粕酶活、小肽、水解度的测定和耐酸性实验,最终得到1株耐酸性较好且蛋白酶活力较高菌株A-12,经形态观察、生理生化实验和分子生物学实验,鉴定为枯草芽孢杆菌(Bacillus subtilis)。利用此菌株与实验室保藏的植物乳杆菌NCU116混合发酵,结果表明,发酵后豆粕中胰蛋白酶抑制因子降解量为98.8%,营养物质如粗蛋白和小肽的含量分别提高了11.04%和13.71%,而且豆粕具有酸香味儿,适口性得到改善;枯草芽孢杆菌A-12可以做为与乳酸菌混和发酵豆粕的1株参考菌株。

To find strains that could mix with lactic acid bacteria to ferment soybean meal with good quality,we isolated 13 strains from mildewed tofu,fermented soybean meal and soy sauce fermented concentrate by transparent cycle plate assay in the primary screening.Then A-12 was found to be the best strain in the secondary screening including the determination of enzyme activity,content of small peptides,degree of hydrolysis and acid-resistance.After physiological and biochemical identification and 16S rRNA sequence analysis,A-12 was identified as Bacillus subtilis.In addition,soybean meal was fermented by mixed culture of Bacillus subtilis A-12 and Lactobacillus plantarum NCU116,wherein the content of trysin inhibitors decreased by 98.8%,on the contrary,the content of crude protein and small peptide increased by 11.04% and 13.71% respectively.The fermented soybean meal had a sour smell and B.subtilis A-12 could be taken as a reference strain for the fermentation of soybean meal mixed with lactic acid bacteria.