ATRAZINE DEGRADATION IN SALINE WASTE-WATER BY PSEUDOMONAS SP STRAIN ADP

Wastewater from atrazine manufacturing plants contains large amounts o f residual atrazine and atrazine synthesis products, which must be rem oved before disposal. One of the obstacles to biological treatment of these wastewaters is their high salt content, eg, up to 4% NaCl (w/v), To enable biological treatment, bacteria capable of atrazine minerali zation must be adapted to high-salinity conditions, A recently isolate d atrazine-degrading bacterium, Pseudomonas sp strain ADP, originally isolated from contaminated soils was adapted to biodegradation of atra zine at salt concentrations relevant to atrazine manufacturing wastewa ter. The adaptation mechanism was based on the ability of the bacteriu m to produce trehalose as its main osmolyte. Trehalose accumulation wa s confirmed by natural-abundance H-1 NMR spectral analysis, The bacter ium synthesized trehalose de novo in the cells, but could not utilize trehalose added to the growth medium, Interestingly, the bacterium cou ld not produce glycine betaine (a common compatible solute), but addit ion of 1 mM of glycine betaine to the medium induced salt tolerance, O smoregulated Pseudomonas sp strain ADP, feeding on citrate decreased t he concentration of atrazine in non-sterile authentic wastewater from 25 ppm to below 1 ppm in less than 2 days, The results of our study su ggest that salt-adapted Pseudomonas sp strain ADP can be used for atra zine degradation in salt-containing wastewater.