Metagenomic assembled genomes unravel purple non‑sulfur bacteria (PNSB) involved in integrating C, N, P biotransformation

Purple non‑sulfur bacteria (PNSB) based bioprocess has been developed to remove carbon, nitrogen and phosphorus from wastewater. However, the interactions of various bioconversion of carbon (C), nitrogen (N) and phosphorus (P) are not completely clear. In this study, a genome-centric metagenomic approach was employed to delineate the shift in microbial community structures and functional genes under light and dark conditions. Seven and 22 metagenomic assembled genomes (MAGs) were recovered from samples in light and dark conditions, accounting for a substantial portion of microbes. Under light, Rhodopseudomonas palustris promoted complex metabolic processes and interactions for C, N and P conversions. Burkholderia contaminans was discovered as new potential organisms for simultaneous C, N and P removal. Metagenomics analysis confirmed genes involved in the synthesis of glycogen, poly-β-hydroxybutyrate, poly-P, amino acids and carotenoids in R. palustris. The substrate transformation mechanisms and potential pathways were proposed according to the detected metabolites. Our findings provided insights into a new biological system with simultaneous C, N and P bioconversions, and improved the understanding of interactions among the key populations.