Roles of semiconductive minerals in metabolic activity of microorganisms

为了研究半导体矿物在微生物呼吸活动中的作用，我们在电化学池中培养了异化金属还原细菌Shewanella loihica PV-4，并检测了细胞表面相关的氧化铁纳米胶体对细胞外电子传递效率的影响。在细胞培养中加入α-Fe_2O_3后，呼吸电流显著提高(50倍以上)。体内电化学研究表明，从细胞注入到胶体导带的电子可以在不使用或不需要可溶性电子穿梭的情况下，从细胞表面长距离移动。这一发现表明，微生物有能力利用半导体矿物在厌氧环境中传输和共享电子。

To examine the roles of semiconductive minerals in the respiratory activity of microorganisms, we cultured the dissimilatory metal-reducing bacterium, Shewanella loihica PV-4, in an electrochemical cell and examined the influence of cell surface-associated Fe-oxide nanocolloids on the extracellular electron-transfer efficiency. The respiratory current was greatly improved (over 50 fold) when α-Fe_2O_3 were supplemented into the cell cultures. In vivo electrochemical studies have revealed that electrons injected from the cells to the conduction band of colloids to move long distances from cell surfaces without the use or requirement of soluble electron shuttles. This finding suggests the microbial ability to exploit semiconductive minerals for transporting and sharing electrons in anaerobic environments.