Microbial interactions in thermophilic anaerobic digestion with carbon cloth revealed by high-throughput sequencing of microscale single flocs

We added carbon cloth into thermophilic anaerobic digestion reactors to investigate their effects on reactor performance and microbial interactions. Our results revealed that the efficiency of the thermophilic digester was improved by carbon cloth addition, and the micro-scale community composition had shown a significant shift. Since these interacting microorganisms generally only cooccur within micro-scale patches, the co-occurrence relationships captured within micro-scale single flocs would provide deeper and more reliable insight into the microbial interactions within the AD process. Therefore, in this study, by coupling amplicon sequencing of hundreds of microscale single flocs, with NGS-based metagenomics and RNA-seq of the thermophilic AD community, we found i) Pseudomonas have spectacular biofilm formation capability; ii) Interaction between Clostridium and Thermotogaceae was steadily observed in all experimental conditions; iii) Carbon cloth addition promoted the direct interspecies electron transfer (DIET) between syntrophic Syntrophomonas and denitrification process of Rhodocyclaceae.