QS Inhibitors vs. Biofouling

The marine environment is a hazardous place for both natural and artificial substrates because they quickly become colonized by micro and macroorganisms. This is commonly known as Biofouling, and this costs millions of pounds each year to prevent and or treat. Biofouling causes problems for boats as the organisms can create drag and increase fuel consumption or they can simply affect jetties or constructions in the water by corrosion creating structural defects.

The search for natural products in the marine environment is vast and many believe the answers too many problems reside within marine organisms. In this study the authors screened seventy eight natural product compounds (mainly from marine organisms, but also some terrestrial plants) for the inhibition of bacterial quorum sensing (QS) using a reporter strain Chromobacterium violaceum CV017.

The authors used QS inhibition bioassays using the reporter strain, which produces N-hexanoyl homoserine lactone, this induces production of the purple pigment violacein via the AHL receptor CviR. Of the seventy eight screened natural products only fifty percent inhibited QS of the reporter strain and twenty four were non-toxic.

After the screening method the authors then proceeded onto a mesocosm experiment. During the screening method they identified kojic acid as a QS inhibitor which is commercially available, due to the availability the authors decided to diffuse this in unfiltered sea water to a concentration of 330 µM and 1mM. Sterile microscope slides were then immersed for seven days. At the end of the seven days the slides were viewed via epifluorescence microscopy and counted.

The results showed that kojic acid inhibited the formation of microbial communities on the glass slides. Compared to the control which lacked kojic acid the presence of both bacteria and diatoms decreased in the mesocosm experiment, the authors concluded by suggesting the use of natural products for controlling Biofouling communities.

A review of; Dobretsov, S., Teplitski, M., Bayer, M., Gunasekera, S., Proksch, P., & Paul, V. J. (2011). Inhibition of marine biofouling by bacterial quorum sensing inhibitors. Biofouling, 27(8), 893-905.