Russell J B, Sniffen C J, Van Soest P J
J Dairy Sci. 1983 Apr;66(4):763-75. doi: 10.3168/jds.S0022-0302(83)81856-6.
Mixed rumen bacteria were incubated in media containing salts, ammonia, vitamins, volatile fatty acids, sulfide, and casein. When initial cell density was 1.0 absorbance unit and mixed carbohydrates (glucose, sucrose, maltose, cellobiose, and soluble starch) were provided at 0, 40, 80, and 160 mg/liter per h, cell growth was limited by carbohydrates, average bacterial growth rate was slow (less than .07/h), and types of bacteria did not appear to change during 7 h. Growth was small if casein was the sole source of energy. Addition of casein to incubations fed carbohydrates caused cell yield to double. Casein hydrolysis was accompanied by marked accumulation of peptides that were metabolized slowly by rumen bacteria. High pressure liquid chromatography indicated that the peptide pool was composed primarily of four fractions. Carbohydrate availability or bacterial growth had little influence on proteolysis or peptide accumulation. Ammonia production was always inversely proportional to rate of carbohydrate feeding. Nitrogen-15 labeling studies indicated that 66% of the cell nitrogen was derived directly from casein at all rates of carbohydrate addition. If average bacterial growth rate was approximately .07/h, little casein entered the ammonia pool even though large amounts of peptide or casein remained undegraded.
将混合瘤胃细菌在含有盐、氨、维生素、挥发性脂肪酸、硫化物和酪蛋白的培养基中培养。当初始细胞密度为1.0吸光度单位，且每小时提供0、40、80和160毫克/升的混合碳水化合物（葡萄糖、蔗糖、麦芽糖、纤维二糖和可溶性淀粉）时，细胞生长受碳水化合物限制，细菌平均生长速率缓慢（低于0.07/小时），且在7小时内细菌种类似乎未发生变化。如果酪蛋白是唯一的能量来源，生长量很小。向以碳水化合物为食的培养物中添加酪蛋白会使细胞产量翻倍。酪蛋白水解伴随着肽的显著积累，瘤胃细菌对这些肽的代谢缓慢。高压液相色谱表明，肽库主要由四个部分组成。碳水化合物的可利用性或细菌生长对蛋白水解或肽积累影响很小。氨的产生总是与碳水化合物投喂速率成反比。氮-15标记研究表明，在所有碳水化合物添加速率下，66%的细胞氮直接来自酪蛋白。如果细菌平均生长速率约为0.07/小时，即使大量肽或酪蛋白仍未降解，进入氨池的酪蛋白也很少。
