No bacteriophages (control) set

In this study, a cocktail of bacteriophages active against a New Delhi metallo beta lactamase (NDM)-positive E. coli PI-7 were isolated fromm municipal wastewater and tested for their lytic effect against the bacterial host. The bacteriophages were specific against E. coli PI-7, and when applied to activated sludge, caused only a transient perturbation to the sludge microbiota between bacteriophage-spiked and control reactors for a short period. Subseqeuntly, bacteriophages were added to sensitize this pathogenic strain to solar irradiation. Solar irradiation coupled with bacteriophages successfully reduced the length of the lag-phase for E. coli PI-7 from 4.11 ± 0.78 h to 1.82 ± 0.60 h in phosphate buffer solution. The reduction of lag-phase length effect was also observed in filtered wastewater effluent and chlorinated effluent. Gene expression analysis of solar-irradiated E. coli PI-7 revealed downregulation of cell wall functions in presence of bacteriophages, making the bacteria more susceptible to damage by solar irradiation and to bacteriophage infection. Downregulation of functions implicated in scavenging and detoxifying reactive oxygen species induced by solar irradiation was also observed in bacteriophage-infected E. coli PI-7 exposed to solar irradiation. Our findings suggest that bacteriophages can be used as low-cost and environmentally safe biocontrol tool to complement solar irradiation in mitigating of the persistence of antibiotic resistant bacteria in reuse waters.