Martínez-Force E, Benítez T
Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Spain.
Biotechnol Prog. 1995 Jul-Aug;11(4):386-92. doi: 10.1021/bp00034a004.
Variations of the yeast free amino acid pool under different culture conditions were studied in two Saccharomyces strains, the laboratory haploid strain S288C and the industrial fermentative yeast IFI256. The internal amino acid pool of both strains was measured when grown in laboratory (minimal and complete) versus semiindustrial (molasses with or without added biotin and/or diammonium phosphate) media, in fermentable (glucose, fructose, sucrose) versus respirable (glycerol) carbon sources, in different temperatures (22, 30, and 37 degrees C), pHs (2.0-4.75), and growth rates (0.018-0.24 h-1) in continuous culture, and at different phases of the growth curve in batch culture (lag, exponential, early and late stationary). Results indicated that environmental conditions, particularly the presence of amino acids in the media, enormously influenced the intracellular amino acid concentration. Higher values were detected in molasses than in laboratory media and in fermentable carbon sources (glucose, fructose, sucrose) than in glycerol. Variations in the amino acid pool along the growth curve were greater at 37 degrees C than at other temperatures; in all cases, the highest values were measured at the beginning of the exponential phase. In continuous culture and at different growth rates, intracellular free amino acid concentrations increased by 3-10-fold when the growth rate was lower than 0.05 h-1, representing 20-35% of the total (free plus protein) amino acid content and indicating that amino acid yield was a partly growth-linked parameter.
在两种酿酒酵母菌株中研究了不同培养条件下酵母游离氨基酸库的变化，这两种菌株分别是实验室单倍体菌株S288C和工业发酵酵母IFI256。当两种菌株在实验室（基本培养基和完全培养基）与半工业（添加或不添加生物素和/或磷酸二铵的糖蜜）培养基中生长时，在可发酵（葡萄糖、果糖、蔗糖）与可呼吸（甘油）碳源中，在不同温度（22、30和37摄氏度）、pH值（2.0 - 4.75）以及连续培养中的不同生长速率（0.018 - 0.24 h⁻¹）下，以及在分批培养的生长曲线的不同阶段（延迟期、指数期、早期和晚期稳定期）时，测量了它们的细胞内氨基酸库。结果表明，环境条件，特别是培养基中氨基酸的存在，极大地影响了细胞内氨基酸浓度。在糖蜜中检测到的值高于实验室培养基中的值，在可发酵碳源（葡萄糖、果糖、蔗糖）中检测到的值高于甘油中的值。氨基酸库沿生长曲线的变化在37摄氏度时比在其他温度时更大；在所有情况下，最高值是在指数期开始时测得的。在连续培养和不同生长速率下，当生长速率低于0.05 h⁻¹时，细胞内游离氨基酸浓度增加了3 - 10倍，占总（游离加蛋白质）氨基酸含量的20 - 35%，这表明氨基酸产量是一个部分与生长相关的参数。
