Inactivation of bacteriophages by high levels of dissolved CO ₂

Abstract

We developed a system with high levels of dissolved CO ₂ for water disinfection. Bacteriophages MS2, Qβ and ΦX174 were selected as the inactivation targets. A relatively mild inactivation effect was observed on MS2 and Qβ at different initial concentrations of dissolved CO ₂ at 0.3 MPa in 20–30 min. When the pressure was increased to 0.6 MPa, the inactivation of MS2 and Qβ was differentially improved. However, this system was less effective for the inactivation of ΦX174. The capsid surface property is a probable reason for the low inactivation of ΦX174. The pH was not a key factor in the inactivation of bacteriophages; moreover, the results obtained using alternative gases (pressurized air and O ₂) indicated that only CO ₂ inactivated these bacteriophages. A comparison between the results of real time polymerase chain reaction (RT-PCR) and plaque assay showed that some RNA moved out from the capsid after treatment. Capsid damage by CO ₂ expansion was the likely mechanism of inactivation with our method.

Keywords:

• inactivation
• bacteriophage
• high levels of dissolved CO ₂
• RT-PCR
• capsid

Acknowledgements

This research was supported by the Grant-in-Aid for Scientific Research (No. 21560571, 2009) from the Japan Society for the Promotion of Science.

Additional information

Notes on contributors

M. Sekine

Current Address: Rajamangala University of Technology, Division of Biology, Faculty of Science and Technology, Thanyaburi, Pathumthani, 12110 Thailand.