Profenofos removal by pseudomonas plecoglossicida PF1 and acinetobacter baylyi GFJ2 in free and immobilized cell forms and their motility

Abstract

Profenofos, a widely used pesticide, has been reported contamination in environment. This study investigated profenofos removal using the immobilized bacterial cells. Cell movement ability related to biodegradation performance was emphasized. Two profenofos-degrading strains, Pseudomonas plecoglossicida PF1 (PF1) and Acinetobacter baylyi GFJ2 (GFJ2) which were motile and non-motile bacteria, respectively were applied. The study divided into 2 parts. For the first part, characterization of profenofos biodegradation by PF1 and GFJ2 influencing by environmental conditions (effects of pH, temperature, and profenofos concentration) was performed. For the second part, the applications of the immobilized cells in batch (effects of the immobilized cell sizes and inorganic salts) and column (effect of profenofos concentrations) tests were examined to accomplish on the gap knowledge between the removal efficiency and behavior of the microorganisms after being immobilized in the matrices comparing to the free cell. The well-known cell entrapment matrix, calcium alginate (CA), was selected. The result showed that both PF1 and GFJ2 were the potential profenofos-degrading microorganisms with a high profenofos removal percentage (60-90%). Optimal conditions for profenofos biodegradation were at pHs of 5.30-7.87, temperatures of 20-40 °C, and profenofos concentrations of 10-200 mg/L. For the batch experiment, the bead size obviously affected the profenofos removal performance. The suitable bead size in this study was 4 mm-diameter. PF1 was positive in motility assays. PF1 got attraction by profenofos resulting in high removal efficiency. For the column experiment, the immobilization technique well retained both motile and non-motile cells. It was also found natural cell colonization on sand in the free cell columns led to similar profenofos removal performance by the free and immobilized cells (60-90%). For the long term, motile bacterium (PF1) either in free or immobilized cell forms performed better than GFJ2.