Efficacy of Nanobubbles Alone or in Combination with Neutral Electrolyzed Water in Removing Escherichia coli O157:H7, Vibrio parahaemolyticus, and Listeria innocua Biofilms

Due to the relatively high tolerance and resistance to sanitizers, biofilms can persist in the environment resulting in cross-contamination. The overall goal of this study was to evaluate the impact of nanobubbles (NB) alone and in combination with neutral electrolyzed water (NEW) on different microbial biofilms including Escherichia coli O157:H7, Vibrio parahaemolyticus, and Listeria innocua on plastic and stainless steel (SS) coupons. NB alone completely removed V. parahaemolyticus biofilm on both plastic and SS coupons after 2 min. NB alone caused about a 1 to 3 log CFU/cm(2) reduction of E. coli and L. innocua biofilms, while a complete reduction was observed only after combining NB with NEW. The antiadhesion results of NB-treated plastic and SS coupons showed lower bacterial adhesion to NB-treated surfaces indicating that NB can attach to the surface and reduce the surface tension and bacterial adhesion. Surface-enhanced Raman spectroscopy spectra (SERS) and mapping results revealed the ability of NB to remove the bacterial biofilms. Raman spectra intensity was reduced at bands associated with carbohydrates, protein, and DNA indicating extracellular polymeric substance (EPS) disruption. This study demonstrates that NB could be a viable technology for removing microbial biofilms from surfaces and enhancing the efficacy of conventional sanitizers.

Automated summary

This study evaluated the impact of nanobubbles and neutral electrolyzed water on different microbial biofilms, finding that nanobubbles alone or in combination with neutral electrolyzed water could effectively remove biofilms, reduce bacterial adhesion, and show potential as a new technology to enhance the efficacy of conventional sanitizers.