Pyruvate Accelerates Palladium Reduction by Regulating Catabolism and the Electron Transfer Pathway in Shewanella oneidensis
Pyruvate Accelerates Palladium Reduction by Regulating Catabolism and the Electron Transfer Pathway in Shewanella oneidensis
复制标题
丙酮酸通过调节希瓦氏菌的分解代谢和电子转移途径加速钯还原。
DOI：
10.1128/aem.02716-20
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发表时间：
2021-04-01
影响因子：
4.4
通讯作者：
Wu, Chao
中科院分区：
文献类型：
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作者：
Cheng, Yuan-Yuan;Wang, Wen-Jing;Wu, Chao
希瓦氏菌具有较强的胞外电子转移能力和遗传可塑性，是电化学活性菌（EAB）的典型菌株。在本研究中，我们以钯离子[Pd(II)]的还原为模型，研究了碳源对山参EET的影响，发现与乳酸相比，丙酮酸大大加速了静息细胞对Pd（II）的还原。当丙酮酸作为碳源时，Mtr途径和氢化酶都在Pd （II）还原中发挥作用。此外，与摄食乳酸的海苔相比，摄食乳酸的海苔中参与丙酮酸分解代谢的甲酸脱氢酶、Mtr通路和氢化酶的转录水平上调。从机制上讲，丙酮酸分解代谢和电子转移到Pd（II）的电子生成的增强解释了丙酮酸对Pd（II）还原的作用。有趣的是，丙酮酸调节这些基因的转录并显著提高Pd（II）还原能力需要一个2小时的时间窗口，这表明在蛇梨中丙酮酸的感知和反应是有层次调控的。EET独特的呼吸作用对金属元素的生物地球化学循环和EAB的多种应用具有重要意义。虽然碳源是细菌代谢的决定因素，但对EET碳源调控的研究却很少。在本研究中，我们报道了葡萄球菌EET的丙酮酸特异性调控和改善，并揭示了其潜在的机制，为该细菌的EET效率的工程和提高提供了潜在的靶点。本研究揭示了碳源在EAB厌氧呼吸中的调节作用，为EET的多种应用提供了一个新的视角。
Shewanella oneidensis is a model strain of electrochemically active bacteria (EAB) because of its strong capability of performing extracellular electron transfer (EET) and its genetic tractability. In this study, we investigated the effect of carbon sources on EET in S. oneidensis by using reduction of palladium ions [Pd(II)] as a model and found that pyruvate greatly accelerated Pd(II) reduction compared with lactate by resting cells. Both the Mtr pathway and hydrogenases played a role in Pd (II) reduction when pyruvate was used as a carbon source. Furthermore, in comparison with lactate-feeding S. oneidensis, the transcriptional levels of formate dehydrogenases involved in pyruvate catabolism, the Mtr pathway, and hydrogenases in pyruvate-feeding S. oneidensis were upregulated. Mechanistically, the enhancement of electron generation from pyruvate catabolism and electron transfer to Pd(II) explains the pyruvate effect on Pd(II) reduction. Interestingly, a 2-h time window is required for pyruvate to regulate transcription of these genes and profoundly improve Pd(II) reduction capability, suggesting hierarchical regulation for pyruvate sensing and response in S. oneidensis.IMPORTANCE The unique respiration of EET is crucial for biogeochemical cycling of metal elements and diverse applications of EAB. Although a carbon source is a determinant factor of bacterial metabolism, research into the regulation of the carbon source of EET is rare. In this work, we report pyruvate-specific regulation and improvement of EET in S. oneidensis and reveal the underlying mechanism, which suggests potential targets for engineering and improvement of the EET efficiency of this bacterium. This study sheds light on the regulatory role of carbon sources in anaerobic respiration in EAB, providing a way to regulate EET for diverse applications from a novel perspective.