Characterization of Anaerobic Digestion of Chinese Cabbage Waste by a Thermophilic Microorganism Community

To enrich an effective Chinese cabbage waste-anaerobic digesting microorganism community, a mixture of cellulolytic microbial community, anaerobic straw-digesting sludge, and cow dung was loaded in a continuous stirred tank reactor, and the Chinese cabbage wastes were fed as carbon and nitrogenous sources. The methane conversion efficiency reached 235.6 mL/g VS after 37 days of operation. The average biogas producing yield was 452.6 mL/g VS with 10.1 g/(L day) of organic loading rate between day 213 and day 231. This microorganism community could effectively degrade Chinese cabbage waste and filter paper, and the weight losses were 72.6 ± 1.1% and 91.4 ± 2.4% in 7 days, respectively. This microorganism community was further analyzed by high-throughput sequencing of the 16S rRNA gene and shown to have abundant bacterial diversity, but poor archaeal diversity. Longilinea, Candidatus Cloacamonas, and Caldisericum were the top three classes of abundant bacterial community, and the proportional abundances were 7.0%, 5.5%, 3.6%, respectively. Methanothrix and Methanolinea dominated the methanogenic archaeal community and occupied 90.8% proportion of total archaeal abundance.