Thuler D S, Floh E I S, Handro W, Barbosa H R
Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brasil.
J Appl Microbiol. 2003;95(4):799-806. doi: 10.1046/j.1365-2672.2003.02047.x.
This study aims at evaluating the ability of Beijerinckia derxii, a free-living nitrogen (N)-fixing bacterium frequently isolated from tropical soils, to release certain plant growth regulators [indoleacetic acid (IAA), ethylene, polyamines] and amino acids into the growth medium.
The production of those substances was compared using both cultures in which nitrogenase was active (N-free medium) and cultures in which nitrogenase was repressed (combined-N cultures). Those cultures were grown under agitation and in absence of agitation. Total IAA production was higher in agitated, N-free cultures but specific production was greater in combined-N cultures under agitation. Putrescine and spermidine were detected under all conditions tested. Ethylene was produced in both N-free and combined-N cultures. A greatest diversity of amino acids was released in N-free cultures.
There was no inhibition of the production of the analysed substances under conditions where nitrogenase was inactive.
Beijerinckia derxii is potentially a producer of plant-active substances; its presence in the natural environment suggests that this bacterium may contribute to the development of other living organisms.
本研究旨在评估德氏拜叶林克氏菌（一种常从热带土壤中分离出的自生固氮细菌）向生长培养基中释放某些植物生长调节剂[吲哚乙酸（IAA）、乙烯、多胺]和氨基酸的能力。
使用固氮酶有活性的培养物（无氮培养基）和固氮酶受抑制的培养物（复合氮培养物）来比较这些物质的产生情况。这些培养物在振荡和不振荡条件下生长。在振荡的无氮培养物中总IAA产量较高，但在振荡的复合氮培养物中特定产量更高。在所有测试条件下均检测到腐胺和亚精胺。无氮和复合氮培养物中均产生乙烯。无氮培养物中释放的氨基酸种类最多。
在固氮酶无活性的条件下，所分析物质的产生没有受到抑制。
德氏拜叶林克氏菌可能是植物活性物质的生产者；它在自然环境中的存在表明这种细菌可能有助于其他生物的生长发育。
