Glazebrook M A, Vining L C, White R L, Smith K C, Chedrawy E G
Biology Department, Dalhousie University, Halifax, N.S., Canada.
Can J Microbiol. 1993 May;39(5):536-42. doi: 10.1139/m93-076.
5-Hydroxy-4-oxonorvaline (HON) was produced optimally by Streptomyces akiyoshiensis in media containing starch and casein supplemented with high concentrations of phosphate and magnesium sulfate; cultures grown at initial pH values between 6.3 and 6.6 yielded HON titres of 13-14 mM. Physiological analysis of HON production provided evidence that the excess inorganic constituents in this medium played an important role in optimizing production. In simple defined media buffered at pH 5.5-6.0 and inoculated with either a spore suspension or washed vegetative mycelium, formation of HON was less than one-third the amount produced in the starch-casein-salts medium. Production was markedly affected by the carbon and nitrogen sources used; media containing starch and potassium nitrate or aspartate supported the highest yields of HON. In starch-nitrate media, production was suppressed by excess nitrogen source, and the HON titre decreased 3-fold as the phosphate content was increased from 0.5 to 5 mM; growth was not appreciably altered. The results suggest that the high level of HON production in the complex starch-casein-salts medium is associated with sequestration of metabolic ammonium and reduced availability of phosphate through formation of the poorly soluble magnesium ammonium phosphate.
5-羟基-4-氧代正缬氨酸（HON）由秋吉链霉菌在含有淀粉和酪蛋白并补充高浓度磷酸盐和硫酸镁的培养基中最佳合成；在初始pH值为6.3至6.6之间培养的菌株产生的HON滴度为13 - 14 mM。对HON合成的生理分析表明，该培养基中过量的无机成分在优化合成过程中发挥了重要作用。在pH值为5.5 - 6.0缓冲的简单限定培养基中接种孢子悬浮液或洗涤过的营养菌丝体，HON的形成量不到淀粉 - 酪蛋白 - 盐培养基中产量的三分之一。产量受到所用碳源和氮源的显著影响；含有淀粉和硝酸钾或天冬氨酸的培养基支持HON的最高产量。在淀粉 - 硝酸盐培养基中，过量的氮源会抑制产量，并且随着磷酸盐含量从0.5 mM增加到5 mM，HON滴度下降3倍；生长没有明显改变。结果表明，在复杂的淀粉 - 酪蛋白 - 盐培养基中高水平的HON合成与代谢铵的螯合以及通过形成难溶性磷酸镁铵降低磷酸盐的可用性有关。
