Syntrophus conductive pili demonstrate that common hydrogen-donating syntrophs can have a direct electron transfer option.,The ISME Journal

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Syntrophus conductive pili demonstrate that common hydrogen-donating syntrophs can have a direct electron transfer option.
The ISME Journal ( IF 10.8 ) Pub Date : 2020-01-02 , DOI: 10.1038/s41396-019-0575-9
David J F Walker _{1,

2} , Kelly P Nevin ₁ , Dawn E Holmes _{1,

3} , Amelia-Elena Rotaru _{1,

4} , Joy E Ward ₁ , Trevor L Woodard ₁ , Jiaxin Zhu ₅ , Toshiyuki Ueki ₁ , Stephen S Nonnenmann _{2,

5} , Michael J McInerney ₆ , Derek R Lovley _{1,

2}

Affiliation

Syntrophic interspecies electron exchange is essential for the stable functioning of diverse anaerobic microbial communities. Hydrogen/formate interspecies electron transfer (HFIT), in which H2 and/or formate function as diffusible electron carriers, has been considered to be the primary mechanism for electron transfer because most common syntrophs were thought to lack biochemical components, such as electrically conductive pili (e-pili), necessary for direct interspecies electron transfer (DIET). Here we report that Syntrophus aciditrophicus, one of the most intensively studied microbial models for HFIT, produces e-pili and can grow via DIET. Heterologous expression of the putative S. aciditrophicus type IV pilin gene in Geobacter sulfurreducens yielded conductive pili of the same diameter (4 nm) and conductance of the native S. aciditrophicus pili and enabled long-range electron transport in G. sulfurreducens. S. aciditrophicus lacked abundant c-type cytochromes often associated with DIET. Pilin genes likely to yield e-pili were found in other genera of hydrogen/formate-producing syntrophs. The finding that DIET is a likely option for diverse syntrophs that are abundant in many anaerobic environments necessitates a reexamination of the paradigm that HFIT is the predominant mechanism for syntrophic electron exchange within anaerobic microbial communities of biogeochemical and practical significance.

中文翻译：

Syntrophus 导电菌毛表明，常见的供氢性菌毛可以具有直接电子转移选项。

同养种间电子交换对于各种厌氧微生物群落的稳定运作至关重要。氢/甲酸盐种间电子转移 (HFIT)，其中 H2 和/或甲酸盐充当可扩散的电子载体，被认为是电子转移的主要机制，因为大多数常见的同养生物被认为缺乏生化成分，例如导电菌毛（e-pili），直接种间电子转移（DIET）所必需的。在这里，我们报告了 Syntrophus aciditrophicus 是 HFIT 研究最深入的微生物模型之一，它产生 e-pili 并且可以通过 DIET 生长。假定的 S. aciditrophicus IV 型菌毛基因在 Geobacterthioreducens 中的异源表达产生了相同直径 (4 nm) 的导电菌毛和天然 S. aciditrophicus pili 并在 G. 硫还原菌中实现了远程电子传输。S. aciditrophicus 缺乏通常与 DIET 相关的丰富的 c 型细胞色素。在其他产氢/甲酸盐的同养菌属中发现了可能产生 e-菌毛的菌毛基因。发现 DIET 是许多厌氧环境中丰富的多种同养菌的一种可能选择，这一发现需要重新审视 HFIT 是厌氧微生物群落中生物地球化学和实际意义的同养电子交换的主要机制的范式。

更新日期：2020-01-17

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