Correlations between microbial community and C:N:P stoichiometry during the anaerobic digestion process

Highlights: • As digestion prolonged, C:N ratio decreased, while C:P and N:P increased. • Microbial diversity strongly related to process properties and C:N:P ratios. • Both archaeal and bacterial dominant order significantly responded to C:N:P ratios. • Process variables explained 94.1% (archaea) and 96.6% (bacteria) of total variation. -- Abstract: Ecological stoichiometry (C:N:P ratios) has been widely used to indicated the complicated microbial ecology system and microbial community, however, limited researches have been done in the anaerobic digestion process. In this study, different responses of microbial community to C:N:P stoichiometry were investigated. Results showed that bacterial diversity were higher than archaea; Beta diversity was decreased then remained stable and strongly correlated to C:N:P ratios, while it was not significant for alpha diversity. Furthermore, considering the archaeal dominant order, Methanomicrobiales showed no significant correlation with C:N:P stoichiometric ratios, but closely related to C, Methanosarcinales was positively influenced by C:N ratio, and Methanobacteriales was significantly and negatively impacted by N:P ratio. For bacteria, Clostridiales and Sphaerochaetales closely and positively related to N, Bacteroidales significantly and negatively related to P, but positively to C:N ratio, and Spirochaetales positively related to C. Moreover, changes of microbial taxa were significantly correlated with all considered process variables, which explained 94.1% and 96.6% of total variation in archaea and bacteria taxa, respectively. It is worthy note that these results could be used to predict the process performance and indicate the complicated microbial community by using the simple C:N, C:P and N:P ratios.