Genetics of Prokaryotes, Faculty of Biology & CeBiTec, Bielefeld University, 33615 Bielefeld, Germany.
Wageningen Plant Research, Wageningen University & Research, 6708PB Wageningen, The Netherlands.
J Agric Food Chem. 2022 May 11;70(18):5634-5645. doi: 10.1021/acs.jafc.2c01042. Epub 2022 May 2.
Indole is produced in nature by diverse organisms and exhibits a characteristic odor described as animal, fecal, and floral. In addition, it contributes to the flavor in foods, and it is applied in the fragrance and flavor industry. In nature, indole is synthesized either from tryptophan by bacterial tryptophanases (TNAs) or from indole-3-glycerol phosphate (IGP) by plant indole-3-glycerol phosphate lyases (IGLs). While it is widely accepted that the tryptophan synthase α-subunit (TSA) has intrinsically low IGL activity in the absence of the tryptophan synthase β-subunit, in this study, we show that TSA functions as a IGL and can support fermentative indole production in strains providing IGP. By bioprospecting additional bacterial TSAs and plant IGLs that function as IGLs were identified. Capturing indole in an overlay enabled indole production to titers of about 0.7 g L in fermentations using strains expressing either the endogenous TSA gene or the IGL gene from wheat.
吲哚在自然界中由多种生物产生，具有特征性气味，描述为动物、粪便和花卉的气味。此外，它有助于食品的风味，应用于香料和香精行业。在自然界中，吲哚是由细菌色氨酸酶（TNAs）从色氨酸合成的，或者由植物吲哚-3-甘油磷酸裂解酶（IGLs）从吲哚-3-甘油磷酸合成的。虽然人们普遍认为色氨酸合酶α亚基（TSA）在没有色氨酸合酶β亚基的情况下内在地具有低 IGL 活性，但在这项研究中，我们表明 TSA 作为一种 IGL，可以在提供 IGP 的菌株中支持发酵吲哚的产生。通过生物勘探，鉴定出了其他具有 IGL 功能的细菌 TSA 和植物 IGL。通过在覆盖物中捕获吲哚，使用表达内源 TSA 基因或小麦 IGL 基因的菌株进行发酵，使吲哚的产量达到约 0.7 g/L。
