APPLICATION OF QUORUM QUENCHING TO CONTROL MICROBIAL BIOFOULING IN MEMBRANE BIOREACTORS

Abstract

Novel membrane bioreactor (MBR) fouling control through quorum sensing was evaluated in this research project. Firstly, a motility based assay was developed for identification of quorum quenchers and autoinducers to overcome the difficulty of needing complicated microbiological work for application of quorum quenching. The assay also identified 2 plant extracts to be effective quenchers for AHL and AI-2 quorum sensing systems, respectively. Next, quorum quenching through 2 wild-type quorum quenching bacteria, Bacillus cereus and Pseudomonas putida, was evaluated for fouling reduction in MBRs in 2 phases; in phase 1 free cells were dosed while in phase 2 the bacteria were immobilized on EMMC (entrapped-mixed-microbial-cell) cellulose-triacetate bioballs. Results showed P. putida was better at fouling control as free cells, but B. cereus significantly reduced fouling in the immobilized form. Motility assays results for both phases showed bacteria produced quorum quenching effects, suggesting fouling reduction was due to quorum quenching.