Molecular analysis of the major capsid genes (g23) of T4-type bacteriophages in an upland black soil in Northeast China

Bacteriophages (phages) are the most abundant biological entities on the planet and are important as the greatest genomic reservoirs in both marine and terrestrial environments. In this study, we analysed T4-type phage communities in an upland black soil by monitoring g23 clones in DNA extracted from seasonal soil samples with no fertilizer, chemical fertilizers, chemical fertilizers plus manure, and natural restoration treatments. PCR products with degenerate primers MZIA1bis and MZIA6 were subjected to denaturing gradient gel electrophoresis. In total, 46 clones with different g23 sequences were obtained. Phylogenetic analyses indicated that T4-type phage communities in the upland black soil were distinctly different from those in marine environments and in an Antarctic lake, which strongly suggested that T4-type phage communities in soil differed from those in aquatic environments. Among 46 clones, 18 clones formed clusters with the clones from rice field soils, 14 clones formed three new clusters, and 13 clones were left as ungrouped, which indicated that T4-type phage communities in the upland black soil were relatively similar to those in rice field soils but that specific communities also inhabit in the upland black soil exclusively.