培养条件对产酸克雷伯氏菌SG-11生物合成IAA影响的研究

研究了产酸克雷伯氏菌（Ｋｌｅｂｉｓｅｌｌａ ｏｘｙｔｏｃａ）ＳＧ－１１菌株的培养条件对其ＩＡＡ生物合成的影响。结果表明：该菌生长到稳定期时才开始大量产生ＩＡＡ；在基本培养基中，该菌对不同氮源的利用有别，在以（ＮＨ４）２ＳＯ４为氮源时，ＩＡＡ的产量最高，作为碳源的葡萄糖当加入浓度为６ｇ／Ｌ时，游离态ＩＡＡ的产量最高；在ＬＢ培养基中，当ｐ（Ｏ２）由正常值降低１／４时，ＩＡＡ的产生量陡然下降，灭菌前，把

EFFECT OF CULTURAL CONDITIONS ON IAA BIOSYNTHESIS BY KLEBSIELLA OXYTOCA SG-11

The plant hormone IAA, secreted by plant growth-promoting bacteria, is involved in several stages of plant growth and development. However, IAA biosynthesis from bacteria was affected by nutrients and growth conditions of rhizosphere. Researches were conducted to determine the IAA biosynthesis of a diazotroph, Klebsiella oxytoca SG 11, isolated from the rhizoplane of rice plant. The effects of nitrogen sources, glucose, p O 2 and pH on IAA production were studied. The results showed that IAA was significantly biosynthesized by Klebsiella oxytoca SG 11 at the stationary stage and the amount of IAA produced varied with the nitrogen sources in mineral medium. A large amount of IAA was secreted when (NH 4) 2SO 4 was used as nitrogen source; large amount of free IAA was produced in mineral medium with 6 g/L glucose; and the IAA-producing ability decreased sharply in LB medium when the p (O 2) was decreased by 1/4 of the normal. The initial optimum pH of LB medium was 7.2 with large amount of IAA secretion at pH 6.5 after 48 h cultivation. Fig 5, Ref 10