Alteration of fimbria-mediated biofilm formation and virulence in the zoonotic pathogen

With a global rise in industrialization and chemical processing units, the introduction of anthropogenic pollutants into the environment has been on a rise. Aquatic pollutants, unlike terrestrial pollutants, are easily diluted in water environments and exist at a sub-inhibitory concentration (sub-IC). At sub-IC, they do not directly inhibit bacterial growth but can modulate gene expression profiles. Aquaculture industry relies heavily on the use of antibiotics for control of fish pathogens, and the indiscriminate use of antibiotic agents increases antibiotic resistance in the aquatic environment. Previous studies have reported that sub-IC of antibiotics are able to regulate biofilm formation in a variety of pathogenic bacteria. To understand the environmental signals in the biofilm formation of IMPORTANCE: Antibiotics released into aquatic environments often persist at sub-inhibitory concentrations, where they no longer suppress bacterial growth but instead act as signaling molecules. Here, we show that sub-inhibitory erythromycin enhances biofilm formation and virulence in the fish pathogen