Sonophotocatalysis mediated morphological transition modulates virulence and antibiotic resistance in Salmonella Typhimurium

Water resources contaminated with antibiotic-resistant (ABR) gastrointestinal pathogens pose severe health risks to society. Unfortunately, the limitations of traditional water treatment methodologies are leading to the evolution and dissemination of ABR microbes. In this aspect, a sonophotocatalytic (SPC) process is demonstrated for the successful disinfection of ABR Salmonella Typhimurium (STm) using Fe-doped ZnO nanoparticles (Fe–ZnO NPs) under visible-LED light. Reactive oxygen species (ROS) produced during SPC contributed to the detrimental effects on the microbes. In general, little is known regarding how bacteria modulate their phenotypic attributes during the course of disinfection. Our investigations to understand the effects of sublethal SPC on the expression of numerous phenotypic features of STm revealed changes in the virulence and ABR profiles. Sublethal SPC caused STm to adhere more on HCT116 cells, whereas their invasion properties were substantially reduced. The loss of ABR was recorded after sublethal SPC, although the resistance was partially regained after a nutrient source was provided to the bacteria. The manifestation of a morphological transition in STm from rod to cocci observed after sublethal SPC may have resulted in the significant loss of invasiveness and ABR. Further, SPC did not result in any process resistance; thus, it is a good candidate for water disinfection.