Bacteriostatic effect of sequential hydrodynamic and ultrasound-induced stress

AIMS: To elucidate the mechanism of action of a nonchemical microbial control technology employing coupled hydrodynamic and ultrasound-induced stress. METHODS & RESULTS: The effects of a laboratory model system using a commercial nonchemical device on Pseudomonas putida revealed growth and respiration were inhibited without a loss of viability from the treated population. Damage to cell membranes was evident using fluorescent microscopy and a reporter strain containing lux genes fused with a membrane damage stress-response promoter. Other reporter strains also indicated the possible involvement of DNA and protein repair systems. A consequence of treatment was a reduced ability to form biofilms. CONCLUSIONS: The nonchemical device caused a biostatic effect on treated cells induced by sublethal damage to several cellular systems, including cell membranes. SIGNIFICANCE AND IMPACT OF THE STUDY: The study demonstrates that biostasis can be an effective mechanism for microbial control in some industrial systems and provides insight into understanding and applying this device and other nonchemical microbial control technologies to real-world problems of microbial contamination.