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In Situ Spectroelectrochemical Characterization Reveals Cytochrome-Mediated Electric Syntrophy in Geobacter Coculture
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2021-07-01 , DOI: 10.1021/acs.est.1c00356
Xing Liu 1 , Ji Zhan 1 , Lu Liu 1 , Feiting Gan 1 , Jie Ye 1 , Kenneth H Nealson 2 , Christopher Rensing 1 , Shungui Zhou 1
Affiliation  

Direct interspecies electron transfer (DIET) between microbial species prevails in some key microbial consortia. However, the electron transfer mechanism(s) in these consortia is controversial due to lack of efficient characterization methods. Here, we provide an in situ anaerobic spectroelectrochemical coculture cell (in situ ASCC) to induce the formation of DIET coculture biofilm on the interdigitated microelectrode arrays and characterize the electron transfer directly. Two typical Geobacter DIET cocultures, Geobacter metallireducens and wild-type Geobacter sulfurreducens (G.m&G.s) and G. metallireducens and a G. sulfurreducens strain deficient in citrate synthase (G.m&G.s-ΔgltA), were selected. In situ Raman and electrochemical Fourier transform infrared (FTIR) spectroscopy indicated that cytochromes are abundant in the electric syntrophic coculture. Cyclic voltammetry and potential step experiment revealed a diffusion-controlled electron transfer process and the electrochemical gating measurements further demonstrated a cytochrome-mediated electron transfer in the DIET coculture. Furthermore, the G.m&G.s-ΔgltA coculture displayed a higher redox conductivity than the G.m&G.s coculture, consistent with the existence of an intimate and efficient electrical connection between these two species. Our findings provide the first report of a redox-gradient-driven electron transport facilitated by c-type cytochromes in DIET coculture, supporting the model that DIET is mediated by cytochromes and suggest a platform to explore the other DIET consortia.

中文翻译:

原位光谱电化学表征揭示了地杆菌共培养中细胞色素介导的电合成

微生物物种之间的直接种间电子转移 (DIET) 在一些关键微生物群落中盛行。然而,由于缺乏有效的表征方法,这些联盟中的电子转移机制存在争议。在这里,我们提供了一种原位厌氧光谱电化学共培养细胞(原位 ASCC),以诱导 DIET 共培养生物膜在叉指微电极阵列上的形成,并直接表征电子转移。两种典型地杆菌DIET共培养物中,Geobacter metallireducens则和野生型Geobacter菌硫还原(GM&G.s)和G. metallireducensG.硫还原在柠檬酸合酶缺陷型菌株(GM&G.s-Δ的gltA),被选中。原位拉曼和电化学傅里叶变换红外 (FTIR) 光谱表明细胞色素在电共养共培养中丰富。循环伏安法和电位阶跃实验揭示了扩散控制的电子转移过程,电化学门控测量进一步证明了 DIET 共培养中细胞色素介导的电子转移。此外,GM&G.s-Δ的gltA共培养显示出比 Gm&G.s 共培养更高的氧化还原电导率,这与这两个物种之间存在密切而有效的电连接一致。我们的发现提供了第一份关于 DIET 共培养中 c 型细胞色素促进的氧化还原梯度驱动的电子传递的报告,支持了 DIET 由细胞色素介导的模型,并提出了一个探索其他 DIET 联盟的平台。
更新日期:2021-07-20
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