混菌发酵改良棉粕蛋白工艺及协同作用研究

利用筛选到的Aspergillus niger P1和Bacillus subtilis H1混菌发酵改良棉粕蛋白,以提高其利用率。结果表明,混菌发酵的最佳发酵条件为:棉粕 40 g,硫酸铵0.2%,麸皮15%,含水量50%,接种量 15%,同时接菌且两菌接菌比例(A.niger P1 ∶ B.subtilis H1)为2 ∶ 1,发酵温度30 ℃,pH约为6.0,发酵时间 60 h。在此条件下发酵后棉粕小肽含量可提高至18.36%,平均肽链长度可降至4.23,体外消化率可提高至88.59%,显著提高了改良棉粕蛋白的效果。在相同发酵条件下比较单、混菌发酵过程的各营养指标发现:A.niger P1可分泌丰富的酸性蛋白酶,B.subtilis H1可分泌丰富的中、碱性蛋白酶,混菌发酵各种蛋白酶的活性显著提高。混菌发酵将大多数大于10个氨基酸组成的多肽降解为1~3个氨基酸组成的小肽,降解效果明显优于单菌发酵。两菌株具有很好的"协同性",可充分利用棉粕基质,协同改良棉粕蛋白。

Optimization of Mixed Fermentation on Cottonseed Meal and Research on the Synergistic Effect of B.subtilis H1 and A.niger P1

Study on the optimization of B.subtilis H1 and A.niger P1 mixing fermentation to degrade the macromolecular protein of cottonseed meal was carried out. The results showed that the optimal conditions were as follows: cottonseed meal 40 g, (NH₄)₂SO₄ 0.2%, bran 15%, water content 50%, nature pH 6.0, temperature 30 ℃, the optimal time 60 h, the optimal inoculation concentration was 15% and the optimal inoculation ratio 2 ∶ 1 (A.niger P1 ∶ B.subtilis H1). Under the optimal level determined, the content of small peptide increased to 18.36%, the length of average peptide chain decreased to 4.23 and the digestibility of protein increased to 88.59%.A.niger P1 can produce rich acid protease, while B.subtilis H1 can produce rich neutral and alkali protease. Under the combined fermentation, the enzyme activity significantly increased. The peptides composed of more than 10 amino acids in the water-soluble peptides were almost degraded to peptides composed of 1~3 amino acids. In short, combined fermentation was better than single fermentation. The two strains have synergistic effect.