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 Corynebacterium glutamicum TSA functions as a bona fide IGL and can support fermentative indole production in strains providing IGP. By bioprospecting additional bacterial TSAs and plant IGLs that function as bona fide IGLs were identified. Capturing indole in an overlay enabled indole production to titers of about 0.7 g L^–1 in fermentations using C. glutamicum strains expressing either the endogenous TSA gene or the IGL gene from wheat.

中文翻译：

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通过细菌色氨酸合酶 α 亚基和植物吲哚-3-甘油磷酸裂解酶发酵生产吲哚

吲哚是由多种生物在自然界中产生的，并表现出被描述为动物、粪便和花香的特征气味。此外，它有助于食品中的风味，并应用于香料和香精行业。在自然界中，吲哚可以通过细菌色氨酸酶 (TNA) 从色氨酸合成，也可以通过植物吲哚-3-甘油磷酸裂解酶 (IGL) 从吲哚-3-甘油磷酸 (IGP) 合成。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-亚基的情况下具有本质上较低的 IGL 活性，但在本研究中，我们表明谷氨酸棒杆菌TSA 可作为真正的IGL 并且可以支持在提供 IGP 的菌株中发酵产生吲哚。通过对其他细菌 TSA 和植物 IGL 进行生物勘探，确定了作为真正IGL 的功能。在使用表达小麦内源性 TSA 基因或 IGL 基因的谷氨酸棒杆菌菌株的发酵过程中，在覆盖层中捕获吲哚可使吲哚产量达到约 0.7 g L ^{–1的滴度。}