Impact of Extracellular Polymers Produced by Soil Microorganisms on Lindane Transport

Abstract

Transport of a model pesticide (lindane) was enhanced by the extracellular polymers (ECPs) produced by soil microorganisms. ECPs, produced by Gram-negative and Gram-positive microorganisms, main components of which are polysaccharides, proteins, and nucleic acids can act to enhance this transport through porous media. Column studies for Escherichia coli JM109, Bacillus subtilis, Pseudomonas aeruginosa over a range of physiological states were conducted and the results showed that the enhancements of the ECPs on lindane transport were strain specific and were related to microorganisms' physiological states. The ECPs produced by Gram-negative microorganisms worked more efficiently than those of Gram-positive microorganisms. In addition, ECPs seemed to have a greater enhancement effect when produced by bacterial microorganisms in the stationary state (deposition coefficient value of 2.06 hr-1 for E. coli JM109 on silica gel) as determined by Adenosine Triphosphate (ATP) analysis than when produced in logarithmic (2.34 hr-1) and decay states (2.25 hr-1). Infrared Spectroscopy (IR) study of the ECPs found that the compositions, which were composed of both hydrophilic and hydrophobic functional groups, were different for ECPs that had different enhancement effect on lindane transport. It was also concluded that the hydrophicility of the ECPs was the limiting factor for the enhancement effect.

Key words: lindane, transport, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, extracellular polymers (ECPs), physiological states.

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