Potential viral influence on sulfur metabolism in acid sulfate soils

Acid sulfate soils cover extensive areas across the globe and pose profound ecological and economic challenges. While microbial activities associated with sulfur metabolisms primarily mediate the formation process of acid sulfate soils, the potential impact of viruses, known for their roles in infecting microorganisms or encoding auxiliary metabolic genes (AMGs), remains largely unexplored. Here, we characterized the community and biogeochemical impacts of viruses in unoxidized acid sulfate soils (hypersulfidic soils, pH 6.5-7.3) and oxidized acid sulfate soils (sulfuric soils, pH < 3.3) using paired viromes and total metagenomes. Our results revealed higher diversity and distinct composition of viral communities in hypersulfidic soils compared to sulfuric soils. In hypersulfidic soils, we identified 30 times more virus-encoded AMGs and observed an average abundance 6.6 times higher than in sulfuric soils. Particularly, the identification of AMGs associated with assimilatory and dissimilatory sulfate reduction, organosulfur compound degradation, organic matter degradation, and electron transfer implied the potential role of viruses in influencing sulfur cycling and the formation of sulfidic materials in Hypersulfidic soils. The virus-host predictions linked seven lysogenic and 55 lytic vOTUs to sulfate-reducing and sulfur-oxidizing microorganisms in both soils, suggesting that viruses play a role in sulfur cycling through host infection. Altogether, our findings highlight the potential roles of viruses in influencing sulfur cycling processes in acid sulfate soils.