由于乳酸菌缺乏一些生物代谢途径,不能合成生长必需的氨基酸、维生素等物质,营养要求十分苛刻,必需依赖生长环境提供必需氨基酸、维生素等生长因子才能获得高密度生长。应用化学限定培养基进行大豆蛋白水解物、全价氨基酸和生长基本氨基酸3种氮源条件下乳酸菌的生长动力学研究,结果表明：保加利亚乳杆菌和嗜热链球菌在分子量小于5 ku的大豆蛋白水解物培养基中的最大生长速率μmax分别为0.215/h和0.262/h,约为全价氨基酸的2倍,细胞密度增加到5倍。20种全价氨基酸氮源培养基对两种乳酸菌的生长效能很低,保加利亚乳杆菌和嗜热链球菌的最大生长速率分别为0.10/h和0.12/h,pH值只达到pH4.5～5.0。基本氨基酸氮源只能满足乳酸菌生长的最低要求。分子量小于5 ku的大豆蛋白水解物比全价氨基酸对乳酸菌生长具有显著的促进作用,表明乳酸菌生长的最佳氮源是寡肽而不是氨基酸,大豆蛋白水解物可以用作乳酸菌高密度培养添加物。%Due to the lack of various biosynthetic pathways,lactic acid bacteria（LAB） are nutritionally fastidious and unable to synthesize some essential amino acids and vitamins,so that the high-density LAB cultures must depend on exogenous essential amino acids,vitamins and other growth factors.The growth kinetics of LAB were carried on the chemically defined media（CDM） of three kinds of nitrogen sources of minimal amino acids,all amino acids and soy protein hydrolysates（SPH）.Results showed that： the growth μmax of Lactobacillus bulgaricus and Streptococcus thermophilus in the molecular weight less than 5ku SPH media were 0.215 h-1 and 0.262 h-1,respectively,were about 2 twice all amino acids.The cell density of two LAB in the SPH media were 4 times of all amino acids media.The media of all amino acids were low efficiency for L.bulgaricus and S.thermophilus,which growth maximum rates were 0.10 h-1 and 0.12 h-1,respectively,and the pH values of two kinds of cultures decreased only 4.5 to 5.0.Essential amino acids minimal medium can just meet basic requirements for growth of LAB,less than 5ku soy protein hydrolyzate played a significant role for promoting the proliferation of LAB than all amino acids.The oligopeptides in the SPH was the best nitrogen resource for LAB growth,rather than amino acids.Thus SPH can be applied as a kind of additional nitrogen resource ingredients to enhance growth rate of LAB.
展开▼
