Impact of bacterial extracellular polymers on lindane transport

The ECPs (at a concentration of 30 mg/L) extracted from Pseudomonas aeruginosa, Escherichia coli JM109, and Bacillus subtilis cultures in their stationary phase enhanced the transport of a model pesticide (lindane) in a sand column by 46.1, 31.8, and 19.3% (decrease in retardation factor), respectively. This was because lindane had a larger partition coefficient value between the aqueous phase and the extracellular polymers (ECPs) (K-d(om)) than between the aqueous phase and the medium matrix (K-d(s)), and the ECPs had a smaller partition coefficient value between the aqueous phase and the medium matrix (K-d(oms)) than lindane (K-d(s)) Among the ECPs examined, the ECPs extracted from P. aeruginosa had the greatest efficiency in facilitating lindane transport, followed by E. coli JM109 and B. subtilis. It was concluded that when K-d(om) reached a certain value (greater than 10 mL/g), K-dom(s) would be the determining factor in facilitating lindane transport. Increase of the ECP concentration increased the efficiency in facilitating lindane transport until the ECP concentration reached 35 +/- 5 mg/L. Above 35 +/- 5 mg/L, the increase of the efficiency with the increase of the ECP concentration became moderate.