Changes in major capsid genes (g23) of T4-type bacteriophages with soil depth in two Japanese rice fields

Abstract

Although microbial communities in soil are well known to change with soil depth, the changes in viral communities with soil depth have not been documented. This study examined the soil depth profiles of T4-type phage communities in two Japanese rice fields from g23 clones in soil DNA extracts to a depth of 1 m. T4-type phage communities changed with soil depth, and the communities were grouped into two groups: the communities of the surface soil layers, where rice roots developed densely, and those of the subsoil layers. Although coarse- and fine-textured soils were stratified in the subsoil layers in both profiles, denaturing gradient gel electrophoresis band patterns and phylogenetic affiliation of g23 were highly similar to each other among the subsoil layers in both fields, indicating that soil texture did not affect T4-type phage communities in these fields. In addition, some clones had g23 sequences identical to those retrieved from rice fields in Northeast China, indicating that closely related viruses and their hosts distribute across the sea between rice fields in Japan and Northeast China.