Effect of vanillin on quorum sensing of Aeromonas hydrophila in porous media

Abstract

Biological clogging "bioclogging" is the occupation of pore space between soil particles by biological material including microorganisms and their associated structures. Substances, both synthesized and naturally occurring, and referred to as quorum sensing inhibitors or quorum quenchers, can be applied to biological systems to manipulate quorum sensing, the phenomenon by which microbes communicate and signal to adjust their growth based on cell density. One such substance that has been observed to inhibit quorum sensing in biofilm formation of <italic>Aeromonas hydrophila</italic> on membranes is the common food additive, vanillin.

The goal of this study was to apply results from reverse osmosis membrane biofilm research to sand columns contained in permeameters. Microbial clogging of pore space in soils was modeled on the laboratory scale using columns designed with piezometers to monitor hydraulic pressure differentials. Operating under saturated conditions with nutrient solution provided in upward flow from Mariotte bottles, four columns (two with Hunter's minimal media and 50mM sucrose and two with, in addition, 0.16 g/L of vanillin) were inoculated with Aeromonas hydrophila ATCC® 7966TM and run in parallel for six days.

Piezometer readings were recorded periodically and analyzed for change over time corresponding to microbial activity. Scanning electron microscopy analysis following dismantlement of each column provided insight to where and to what extent microbial growth occurred. Future studies could involve several modifications of the experimental technique to test the impact of different concentrations of vanillin on A. hydrophila growth in porous media.