Nutaratat Pumin, Srisuk Nantana, Arunrattiyakorn Panarat, Limtong Savitree
Department of Microbiology, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand.
Center for Advanced Studies in Tropical Natural Resources, NRU-KU, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand.
Arch Microbiol. 2016 Jul;198(5):429-37. doi: 10.1007/s00203-016-1202-z. Epub 2016 Feb 22.
Microorganisms produce plant growth regulators, such as auxins, cytokinins and gibberellins, to promote plant growth. Auxins are a group of compounds with an indole ring that have a positive effect on plant growth. Indole-3-acetic acid (IAA) is a plant growth hormone classified as an indole derivative of the auxin family. IAA biosynthesis pathways have been reported and widely studied in several groups of bacteria. Only a few studies on IAA biosynthesis pathways have been conducted in yeast. This study aimed to investigate IAA biosynthesis pathways in a basidiomycetous yeast (Rhodosporidium paludigenum DMKU-RP301). Investigations were performed both with and without a tryptophan supplement. Indole compound intermediates were detected by gas chromatography-mass spectrometry. Indole-3-lactic acid and indole-3-ethanol were found as a result of the enzymatic reduction of indole-3-pyruvic acid and indole-3-acetaldehyde, in IAA biosynthesis via an indole-3-pyruvic acid pathway. In addition, we also found indole-3-pyruvic acid in culture supernatants determined by high-performance liquid chromatography. Identification of tryptophan aminotransferase activity supports indole-3-pyruvic acid-routed IAA biosynthesis in R. paludigenum DMKU-RP301. We hence concluded that R. paludigenum DMKU-RP301 produces IAA through an indole-3-pyruvic acid pathway.
微生物产生植物生长调节剂，如生长素、细胞分裂素和赤霉素，以促进植物生长。生长素是一组具有吲哚环的化合物，对植物生长有积极作用。吲哚-3-乙酸（IAA）是一种植物生长激素，属于生长素家族的吲哚衍生物。IAA生物合成途径已在几类细菌中得到报道并被广泛研究。在酵母中，仅有少数关于IAA生物合成途径的研究。本研究旨在探究担子菌酵母（沼泽红冬孢酵母DMKU-RP301）中的IAA生物合成途径。研究分别在添加和不添加色氨酸的情况下进行。通过气相色谱-质谱联用仪检测吲哚化合物中间体。在经由吲哚-3-丙酮酸途径的IAA生物合成过程中，发现吲哚-3-乳酸和吲哚-3-乙醇是吲哚-3-丙酮酸和吲哚-3-乙醛酶促还原的产物。此外，我们还通过高效液相色谱法在培养上清液中发现了吲哚-3-丙酮酸。色氨酸转氨酶活性的鉴定支持了沼泽红冬孢酵母DMKU-RP301中吲哚-3-丙酮酸途径的IAA生物合成。因此，我们得出结论，沼泽红冬孢酵母DMKU-RP301通过吲哚-3-丙酮酸途径产生IAA。
