LAUSR

Aerobic composting of anaerobic digested residue (DR) is an effective post-treatment method to develop a zero emission process; however, there are knowledge gaps in the understanding of this process. Microbial succession is a critical parameter for examining the principle of material transformation and maturity throughout the composting process. This study compared the total (DNA level) and active (RNA level) microbial community succession during the DR composting process by using 16S rRNA gene high-throughput sequencing. A significantly higher richness and diversity for the microbial community on the RNA level compared with the DNA level was observed. Beta-diversity analysis revealed significant differences in community composition and dynamics between the DNA and RNA of microbes. Moreover, DNA analysis exhibited large parts of anaerobic microbes in composting samples, indicating its bias to assess the metabolically active microbial community succession. The RNA dataset showed that Proteobacteria, Firmicutes, and Bacteroidetes predominated in the phylum level, while Crenarchaeota was distinctive. This indicated that the members in these phyla are crucial to material transformation and product maturity during the aerobic composting of DR.