Virus communities rather than bacterial communities contribute more on nutrient pool in polluted aquatic environment

The degradation of animal carcasses can lead to rapid waste release (e.g., pathogenic bacteria, viruses, prions, or parasites) and also result in nutrient accumulation in the surrounding environment. However, how viral profile responds and influences nutrient pool (carbon (C), nitrogen (N), phosphorus (P) and sulfur (S)) in polluted water caused by animal carcass decomposition had not been explored. Here, we combined metagenomic analysis, 16S rRNA gene sequencing and water physicochemical assessment to explore the response of viral communities under different temperatures (23 °C, 26 °C, 29 °C, 32 °C, and 35 °C) in water polluted by cadaver, as well as compare the contribution of viral/bacterial communities on water nutrient pool. We found that a total of 15,240 viral species were classified and mainly consisted of Siphoviridae. Both temperature and carrion reduced the viral diversity and abundance. Only a small portion of the viruses (∼8.8 %) had significant negative correlations with temperature, while most were not sensitive. Our results revealed that the viruses had lager contribution on nutrient pool than bacteria. Besides, viral-related functional genes involved in C, N, P and S cycling. These functional genes declined during carcass decomposition and covered part of the central nutrient cycle metabolism (including carbon sugar transformation, denitrification, P mineralization and extracelluar sulfate transfer, etc.). Our result implies that human regulation of virus communities may be more important than bacterial communities in regulating and managing polluted water quality and nutrition.