Community structure analysis of methanogenic flora and optimization for bioaugmentation methane generation from lignite

Abstract:

[Objective] The mixed methanogenic flora with high methane production from Baiyinhua lignite was obtained from several coalmines and an anaerobic polluted water processing tank by enrichment, mixture and domestication. The community structure was analyzed and its methane production condition from lignite was optimized. [Methods] The community structure was analyzed by Miseq high-throughput sequencing. Plackett-Burman and Box-Behnken tests were conducted to screen and optimize the main factors influencing the efficiency of methane production. [Results] The mixed flora (HN+MD+WT) combined with indigenous and exogenous microbial culture produced the highest methane after domestication. The diversity of bacterial community was abundant, in which the dominant portion was Desulfovibrio (belong to proteobacteria, 15.07%), Macellibacteroides (belong to bacteroidetes, 14.6%), Clostridiaceae (belong to Firmicutes, 9.77%), Dethiosulfovibrio (belong to Synergistetes, 8.76%) and Oceanotoga (belong to thermotogae, 8.66%). All the archaea were assigned to Euryarchaeota, and its diversity was single comparatively. Methanocalculus (80.28%) was the most dominant genus. Plackett-Burman test results indicated temperature, concentrations of CoCl₂and NiCl₂ were the most important influencing factors. Box-Behnken test results showed that the optimal conditions were as follows:temperature 36℃, CoCl₂ concentration 0.17 g/L, NiCl₂ concentration 0.02 g/L, under which the methane accumulation is up to 159.3 μmol/g (20 d). [Conclusion] A mixed flora with high methane production could be obtained by domestication. The productivity of methane could be enhanced significantly by optimizing the culture condition.