Effect of surfactants produced by Rhodococcus erythropolis IMV Ac-5017 on single- and dual-species biofilms of phytopathogenic bacteria

Abstract

The aim of this study was to investigate the disruption of biofilms formed by phytopathogenic bacteria using surfactants produced by Rhodococcus erythropolis IMV Ac-5017 in the presence of a yeast-derived inducer and precursors of phytohormone biosynthesis. Surfactants synthesized under different cultivation conditions of R. erythropolis IMV Ac-5017, at low concentrations (0.94–120 μg/mL), effectively disrupted pre-formed mono- and dual-species biofilms of phytopathogenic bacteria, with destruction ranging from 7–84% and 4–69%, respectively. Notably, surfactants produced in the presence of a eukaryotic inducer, even without phytohormone biosynthesis precursors, were effective against dual-species phytopathogenic biofilms at concentrations of 0.94–3.75 μg/mL, achieving 51–69% disruption. The addition of inactivated S. cerevisiae BTM-1 cells or the corresponding supernatant to the cultivation medium further enhanced the synthesis of surfactants, resulting in increased biofilm disruption by 6–42% for single-species biofilms and 3–57% for dual-species biofilms compared with preparations obtained in medium containing erythritol and/or tryptophan without an inducer. These results suggest that the presence of a eukaryotic inducer can modulate the composition and activity of surfactants, potentially by influencing the relative proportions of glyco-, amino-, and neutral lipids in the preparation. Consequently, these findings represent one of the first reports demonstrating the destruction of both single- and dual-species biofilms of phytopathogenic bacteria from the genera Xanthomonas, Pseudomonas, Agrobacterium, Pectobacterium, and Clavibacter by microbial surfactants, highlighting their potential as a sustainable strategy for controlling plant pathogens in agricultural settings. The present data demonstrate the potential of surfactants in crop production to combat phytopathogenic bacterial biofilms, ensuring the safety and quality of raw materials for the food and processing industries.