Fate of coliphage in waste water treatment process and detection of phages carrying the Shiga toxin type 2 gene.

Abundances of phages specific to Escherichia coli in the wastewater treatment process were analyzed. Relatively abundant coliphages were detected in sewage influent. Phages in the influent were found both suspended in liquid phase and attached on the solid particles. Phage concentration was not reduced in the settling tank without chemical agglutination. Anaerobic followed by aerobic treatment of the sewage reduced concentration of suspended phages. Almost no phage was detected as a suspended form in the aerobic tank. Most of the phages were detected as attaching form and were excluded by aggregation with sludge. Using an experimental approach based on the detection of Shiga toxin 2 (Stx 2) gene by a phage enrichment culture followed by nested PCR, bacteriophages carrying Stx 2 gene were detected in the influent, settling tank, and anaerobic tank. It was revealed that the presence of phages carrying Stx 2 gene is common in sewage and these phages are effectively eliminated through sewage treatment process.