Isolation of an uncharacterized methanogen of class thermoplasma from an anaerobic wastewater treatment reactor

Abstract

Conventional wastewater treatment plants account for approximately 3% of the United States’ energy demand1. A potential energy-positive alternative is anaerobic wastewater treatment, which generates methane-rich biogas while producing less biosolids. One challenge of AnWT is ensuring that wastewater is continuously meeting effluent standards. To ensure that this is happening, the mechanism of wastewater transformation in relation to environmental conditions needs to be well understood. At two AnWT in Colorado, namely Plum Creek and Mines Park, established microbial communities consist of numerous anaerobic microbes, including methanogens. Vadin CA 11 is an uncharacterized methanogen of the Thermoplasmata class that could represent up to 7% of the microbial community. Its abundance is different from compartment 2 to compartment 3 of the Mines Park AnWT. Further, Vadin CA 11’s presence has been observed to change with temperature. The goal of this study was to isolate Vadin CA 11 from the Mines Park AnWT. The methanogens with the highest observed relative abundance in the system are Methanobrevibacter, Methanosaeta, and Vadin CA 11. Methanobrevibacter’s metabolism is hydrogeotrophic. Methanosaeta’s metabolism is aceticlastic. Vadin CA 11’s metabolism is expected to be hydrogen dependent methylotrophic.