Soil Ecology Lab, College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing 210095, China.
College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing 210095, China.
Int J Mol Sci. 2018 Feb 1;19(2):443. doi: 10.3390/ijms19020443.
ZZ21 is a plant-beneficial, fluoranthene-degrading bacterial strain found in the rhizosphere. The production of the phytohormone indole-3-aectic acid (IAA) by ZZ21 is thought to contribute to its ability to promote plant growth and remediate fluoranthene-contaminated soil. Using genome-wide analysis combined with metabolomic and high-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses, we characterized the potential IAA biosynthesis pathways in ZZ21. IAA production increased 4.5-fold in the presence of 200 mg·L tryptophan in the culture medium. The transcript levels of and , genes which were predicted to encode aldehyde dehydrogenases, were significantly upregulated in response to exogenous tryptophan. Additionally, metabolomic analysis identified the intermediates indole-3-acetamide (IAM), indole-3-pyruvic acid (IPyA), and the enzymatic reduction product of the latter, indole-3-lactic acid (ILA), among the metabolites of ZZ21, and subsequently also IAM, ILA, and indole-3-ethanol (TOL), which is the enzymatic reduction product of indole-3-acetaldehyde, by HPLC-MS. These results suggest that the tryptophan-dependent IAM and IPyA pathways function in ZZ21.
ZZ21 是一种在根际发现的植物有益、芴降解细菌菌株。人们认为 ZZ21 产生植物激素吲哚-3-乙酸（IAA）有助于其促进植物生长和修复芴污染土壤的能力。本研究采用全基因组分析结合代谢组学和高效液相色谱-质谱（HPLC-MS）分析，对 ZZ21 中潜在的 IAA 生物合成途径进行了表征。在培养基中添加 200mg·L 色氨酸时，IAA 产量增加了 4.5 倍。基因和 ，预测编码醛脱氢酶，对外源色氨酸的响应显著上调。此外，代谢组学分析在 ZZ21 的代谢物中鉴定出中间体吲哚-3-乙酰胺（IAM）、吲哚-3-丙酮酸（IPyA）和后者的酶还原产物吲哚-3-乳酸（ILA），随后通过 HPLC-MS 也鉴定出 IAM、ILA 和吲哚-3-乙醇（TOL），即吲哚-3-乙醛的酶还原产物。这些结果表明，ZZ21 中存在依赖色氨酸的 IAM 和 IPyA 途径。
