CONTROLLING AQUACULTURE PATHOGEN BIOFILM BY CRUDE EXTRACT AND SUPERNATANT OF PHYLLOSPHERE BACTERIA

Abstract

Some infectious-aquaculture pathogens, such as Aeromonas hydrophila, Vibrio harveyi, and Streptococcus agalactiae are able to form biofilm, a protective structure that increases bacterial resistance to some external exposures, for example the antibiotic therapy, making the antibiotic becomes less effective. This ability is supported by the quorum sensing mechanism. Therefore, disruption in quorum sensing mechanism may be a potential way to treat the biofilm formation. The present study was conducted to assess the ability of supernatant and crude extract of some Actinobacteria and phyllosphere bacteria isolates to overcome the biofilms of several aquaculture pathogens. In general, this study consists of several steps, such as primary screening of anti-quorum sensing activity, extraction of bioactive compounds, antibiofilm assay, validation of anti-quorum sensing activity, toxicity assay, and microscopic observation of biofilm. The phyllosphere bacteria isolates showed higher antibiofilm activity compared to the Actinobacteria isolate, where the crude extract had the most ability instead of supernatant. The supernatant and crude extract of all isolates also performed the anti-quorum sensing activities, both qualitatively and quantitatively. Overall, all isolates were potential to be natural sources of antibiofilm agents to control the biofilm of all pathogens used in this study through quorum sensing disruption.