Ecology of viruses in rice fields

摘要

Viruses are the most abundant biological entities in marine and freshwater environments. Many studies have shown the ecological importance of viruses as the greatest genomic reservoirs, in primary production and microbial food web in aquatic environments. However, the viral ecology in the soil environment has been little documented. In this study, we estimated viral abundance in the floodwater of rice fields, and then measured phage-infected bacterial cells for evaluating the importance of phage infection to bacterial hosts in the microbial food web. The diversity and specificity of g23 sequences of T4-type bacteriophages in rice fields were also determined in comparison with those in aquatic environments. Viruses were also the most abundant biological entities in rice fields, and bacteriophages comprised the majority among viral communities. The high frequency of phage-infected bacterial cells indicated that the bacterial mortality from phage lysis could be significant enough to redirect the microbial food web and change the bacterial communities. The majority of g23 sequences of T4-type bacteriophages in rice fields were distantly related to those of marine origins. The g23 genes in rice fields have apparently diverged more compared to marine g23 genes.