The phenomenon of interspecies electron transfer widely exists in natural and engineered systems. The interspecies electron transfer could be accelerated by conductive materials, including MWCNT and graphene. However, conductivity is not the only electrochemical property possessed by biochar. The functional groups on the biochar surface could also exchange electrons with bacteria. Thus, we added the biochars into the coculture system with direct electron transfer ability. The electron transfer rates were significantly related to the oxygen-containing functional groups: the more oxygen-containing functional groups, the faster the substrate consumption. We further verified this effect in the paddy soil, which could generate methane with interspecies electron transfer. The functional groups enhanced the methane generation after the biochar addition; methane generation was greatly related to the electron-donating capacities of biochar. However, after long-period culture, the conductivity gradually adjusted the microbial community structure by increasing the relative abundance of microorganisms with the electrochemical activity. In the microbial interspecies electron transfer process, surface functional groups and biochar conductivity played major roles in different periods.

Microbial interspecies electron transfer and the reactivity of biochars

ACS Fall 2021

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