阿维菌素发酵过程有机酸积累规律与生物合成的关系

对S．avermitilis发酵过程茵体胞内与胞外的几种有机酸浓度进行跟踪测定。通过与产素关联发现低产批次与高产批次有机酸积累有明显不同。低产批次胞内丙酮酸浓度高迭31．6mg／L，此后降至5mg／L以下，而胞外在80h后都开始出现积累；乙酸、柠檬酸与琥珀酸一直都大量出现在胞外，如柠檬酸胞内胞外浓度比值初期低于0．1。这体现出生长期延长以致与产素期重叠过多造成产素偏低。

Correlation between Organic Acids Accumulation and Biosynthesis of Avermectin

Intercellular and extracellular organic acid concentrations of industrial culture of 5. avermitills were analyzed in several typical batches of avermectin fermentation. Experimental results showed that organic acids accumulation in low production batches and high ones were totally different. In low production batch, intercellular pyruvic acid concentrations reached 31.6 mg/L at early stage of process, then de- clined to less than 5 mg/L, while excretion of pyruvic acid could be observed after 80 h of cultivation. Great amount of acetic acid, citric acid and succinic acid were excreated. The ratio of intracellular and extracellular citric acid concentration was even lower than 0.1 in early stage. This phenomenon indicated that the growth phase was extended and was even overlapped a lot with production phase, which was an important reason for the final low potency.