Virus-bacterium interaction involved in element cycles in biological treatment of coking wastewater.

[Display omitted] • A unique viromic profile of CWW treatment was outlined for the AOHO combination. • Viral infection reprogrammed the hosts' metabolic pathways in CWW treatment. • Viruses encoded AMGs involved in element cycles and toxic tolerance of hosts. • Dissolved oxygen shapes the distributions of virus community and AMGs. • The viral auxiliary metabolism improved the CWW treatment efficacy and stability. Although prokaryotic microbes in coking wastewater (CWW) treatment have been comprehensively studied, the ecological functions of viruses remain unclear. A full-scale CWW biological treatment AOHO combination was studied for the virus-bacterium interactions involved in element cycles by metaviromics, metagenomics and physicochemical characteristics. Results showed the unique viromic profile with Cirlivirales and Petitvirales as the dominant viruses infecting functional bacteria hosts. The auxiliary metabolic genes (AMGs) focused on element cycles, including metabolisms of carbon (fadA), nitrogen (glnA), sulfur (mddA and cysK) and phosphorus (phoH). Other AMGs were involved in toxic tolerance of hosts, improving their cell membrane and wall robustness, antioxidant, DNA repair and cobalamin biosynthesis. Vice versa, the bloomed host provided fitness advantages for viruses. Dissolved oxygen was found to be the key factor shaping the distributions of viral community and AMGs. Summarizing, the study exposed the mutual virus-bacterium interaction in the AOHO combination providing stable treatment efficiency. [ABSTRACT FROM AUTHOR]