Soundararajan Mathangi, Ledbetter Rhesa, Kusuma Paul, Zhen Shuyang, Ludden Paul, Bugbee Bruce, Ensign Scott A, Seefeldt Lance C
Department of Chemistry and Biochemistry, Utah State University, Logan, UT, United States.
Department of Biological Sciences, Idaho State University, Pocatello, ID, United States.
Front Microbiol. 2019 Aug 14;10:1817. doi: 10.3389/fmicb.2019.01817. eCollection 2019.
A promising approach for the synthesis of high value reduced compounds is to couple bacteria to the cathode of an electrochemical cell, with delivery of electrons from the electrode driving reductive biosynthesis in the bacteria. Such systems have been used to reduce CO to acetate and other C-based compounds. Here, we report an electrosynthetic system that couples a diazotrophic, photoautotrophic bacterium, TIE-1, to the cathode of an electrochemical cell through the mediator H that allows reductive capture of both CO and N with all of the energy coming from the electrode and infrared (IR) photons. TIE-1 was shown to utilize a narrow band of IR radiation centered around 850 nm to support growth under both photoheterotrophic, non-diazotrophic and photoautotrophic, diazotrophic conditions with growth rates similar to those achieved using broad spectrum incandescent light. The bacteria were also successfully cultured in the cathodic compartment of an electrochemical cell with the sole source of electrons coming from electrochemically generated H, supporting reduction of both CO and N using 850 nm photons as an energy source. Growth rates were similar to non-electrochemical conditions, revealing that the electrochemical system can fully support bacterial growth. Faradaic efficiencies for N and CO reduction were 8.5 and 47%, respectively. These results demonstrate that a microbial-electrode hybrid system can be used to achieve reduction and capture of both CO and N using low energy IR radiation and electrons provided by an electrode.
合成高价值还原化合物的一种有前景的方法是将细菌与电化学电池的阴极耦合，电极提供的电子驱动细菌中的还原生物合成。此类系统已被用于将CO还原为乙酸盐和其他含碳化合物。在此，我们报告了一种电合成系统，该系统通过介质H将固氮光合自养细菌TIE-1与电化学电池的阴极耦合，从而实现对CO和N的还原捕获，所有能量均来自电极和红外（IR）光子。研究表明，TIE-1利用中心波长约为850 nm的窄带红外辐射，在光异养、非固氮和光合自养、固氮条件下均能支持生长，其生长速率与使用广谱白炽灯时相似。这些细菌还在电化学电池的阴极室中成功培养，唯一的电子来源是电化学产生的H，利用850 nm光子作为能量源支持CO和N的还原。生长速率与非电化学条件下相似，表明该电化学系统能够充分支持细菌生长。N和CO还原的法拉第效率分别为8.5%和47%。这些结果表明，微生物-电极混合系统可用于利用低能量红外辐射和电极提供的电子实现对CO和N的还原与捕获。
