Optimization of factors affecting current generation, biofilm formation and rhamnolipid production by electroactive Pseudomonas aeruginosa FA17

Abstract Microbial electrochemical cells (MXCs) have been developed as promising devices mainly for energy generation and wastewater treatment. Among the well-defined electroactive bacteria, Pseudomonas aeruginosa has been demonstrated for its electroactivity through mediated electron transfer in MXCs. In addition to phenazine pigments that mediate external electron transfer (EET), biofilm formation and rhamnolipid production are considered important factors affecting electricity generation by P. aeruginosa in MXCs. In the present study, a local electroactive strain of P. aeruginosa was isolated. Bacterial identification was done by Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and 16S rDNA as P. aeruginosa FA17. Cyclic voltammetric studies showed the appearance of oxidation peaks which contributes to pyocyanin. Plackett-Burman designs were employed to optimize the composition of artificial wastewater (AWW) media for current generation (represented the mediated electron transfer), biofilm formation and rhamnolipid production by FA17. Ammonium chloride was the significant variable affecting electron transfer of FA17 for current generation in three-electrode set-up by using cyclic voltammetry analyses. While phosphate, Sodium dodecyl sulfate (SDS) and chlorides were the major factors influencing biofilm formation by FA17, phosphate, inoculum size, MgSO4.7H2O, pH, and SDS were the significant variables for rhamnolipid production. This study provides knowledge about the electrochemical behavior of mediated electron transfer catalyzed by P. aeruginosa FA17, biofilm formation, and rhamnolipid production in response to medium composition, which leads to the possibility for the future development of power produced by MXCs using the electroactive FA17.