Denitrifying Betaproteobacteria play a key role in the anaerobic degradation of monoaromatic hydrocarbons. We performed a multi-omics study to better understand the metabolism of the representative organism Georgfuchsia toluolica strain G5G6 known as a strict anaerobe coupling toluene oxidation with dissimilatory nitrate and Fe(III) reduction. Despite the genomic potential for degradation of different carbon sources, we did not find sugar or organic acid transporters, in line with the inability of strain G5G6 to use these substrates. Using a proteomics analysis, we detected proteins of fumarate-dependent toluene activation, membrane-bound nitrate reductase, and key components of the metal-reducing (Mtr) pathway under both nitrate- and Fe(III)-reducing conditions. High abundance of the multiheme cytochrome MtrC implied that a porin–cytochrome complex was used for respiratory Fe(III) reduction. Remarkably, strain G5G6 contains a full set of genes for aerobic toluene degradation, and we detected enzymes of aerobic toluene degradation under both nitrate- and Fe(III)-reducing conditions. We further detected an ATP-dependent benzoyl-CoA reductase, reactive oxygen species detoxification proteins, and cytochrome c oxidase indicating a facultative anaerobic lifestyle of strain G5G6. Correspondingly, we found diffusion through the septa a substantial source of oxygen in the cultures enabling concurrent aerobic and anaerobic toluene degradation by strain G5G6.

中文翻译：

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Georgfuchsia toluolica 的蛋白质组学分析揭示了意外的并发需氧和厌氧甲苯降解

反硝化 Betaproteobacteria 在单芳烃的厌氧降解中起关键作用。我们进行了一项多组学研究，以更好地了解代表性有机体Georgfuchsia toluolica的代谢菌株 G5G6 被称为严格厌氧菌，将甲苯氧化与异化硝酸盐和 Fe(III) 还原偶联。尽管基因组具有降解不同碳源的潜力，但我们没有发现糖或有机酸转运蛋白，这与菌株 G5G6 无法使用这些底物一致。使用蛋白质组学分析，我们检测了在硝酸盐和 Fe(III) 还原条件下富马酸盐依赖性甲苯活化、膜结合硝酸盐还原酶和金属还原 (Mtr) 途径的关键成分的蛋白质。多血红素细胞色素 MtrC 的高丰度表明孔蛋白-细胞色素复合物用于呼吸性 Fe(III) 还原。值得注意的是，菌株 G5G6 包含一整套好氧甲苯降解基因，我们在硝酸盐和铁（III）还原条件下检测到好氧甲苯降解酶。我们进一步检测到 ATP 依赖性苯甲酰辅酶 A 还原酶、活性氧解毒蛋白和细胞色素c氧化酶表明菌株 G5G6 的兼性厌氧生活方式。相应地，我们发现通过隔膜的扩散是培养物中氧气的重要来源，使 G5G6 菌株能够同时进行需氧和厌氧甲苯降解。