Biodiversity and core microbiota of key-stone ecological clusters regulate compost maturity during cow-dung-driven composting.

The primary objectives of this study were to explore the community-level succession of bacteria, fungi, and protists during cow-dung-driven composting and to elucidate the contribution of the biodiversity and core microbiota of key-stone microbial clusters on compost maturity. Herein, we used high-throughput sequencing, polytrophic ecological networks, and statistical models to visualize our hypothesis. The results showed significant differences in the richness, phylogenetic diversity, and community composition of bacteria, fungi, and eukaryotes at different composting stages. The ASV191 (Sphingobacterium), ASV2243 (Galibacter), ASV206 (Galibacter), and ASV62 (Firmicutes) were the core microbiota of key-stone bacterial clusters relating to compost maturity; And the ASV356 (Chytridiomycota), ASV470 (Basidiomycota), and ASV299 (Ciliophora) were the core microbiota of key-stone eukaryotic clusters relating to compost maturity based on the data of this study. Compared with the fungal taxa, the biodiversity and core microbiota of key-stone bacterial and eukaryotic clusters contributed more to compost maturity and could largely predict the change in the compost maturity. Structural equation modeling revealed that the biodiversity of total microbial communities and the biodiversity and core microbiota of the key-stone microbial clusters in the compost directly and indirectly regulated compost maturity by influencing nutrient availability (e.g., NH4+-N and NO3--N), hemicellulose, humic acid content, and fulvic acid content, respectively. These results contribute to our understanding of the biodiversity and core microbiota of key-stone microbial clusters in compost to improve the performance and efficiency of cow-dung-driven composting.

Community succession of microbial populations related to CNPS biological transformations regulates product maturity during cow-manure-driven composting.

The main objective of present study was to understand the community succession of microbial populations related to carbon-nitrogen-phosphorus-sulfur (CNPS) biogeochemical cycles during cow-manure-driven composting and their correlation with product maturity. The abundance of microbial populations associated with C degradation, nitrification, cellular-P transport, inorganic-P dissolution, and organic-P mineralization decreased gradually with composting but increased at the maturation phase. The abundance of populations related to N-fixation, nitrate-reduction, and ammonification increased during the mesophilic stage and decreased during the thermophilic and maturation stages. The abundance of populations related to C fixation and denitrification increased with composting; however, the latter tended to decrease at the maturation stage. Populations related to organic-P mineralization were the key manipulators regulating compost maturity, followed by those related to denitrification and nitrification; those populations were mediated by inorganic N and available P content. This study highlighted the consequence of microbe-driven P mineralization in improving composting efficiency and product quality.