ASSESSMENT OF THE DIOXIN DEGRADABLILITY OF SOME BACTERIAL STRAINS ISOLATED FROM CONTAMINATED SOIL AT A SO AIRBASE (HUE)

Abstract

A So Airport is one of the hot spots for dioxin contamination because of the war. Biodegradation of dioxin isomers by microorganisms is an environmentally friendly method, capable of restoring contaminated land. In this study, from dioxin-contaminated soil samples at A So Airport (Thua Thien Hue), 9 strains of microorganisms capable of degrading persistent organic compounds were isolated. In which, 2 strains capable of degrading all 17 dioxin isomers at high concentrations were identified. The AS2 strain belongs to the genus Klebsiella and is named Klebsiella sp. AS2, whose registration number on GenBank is ON890383. The AS3 strain belongs to the genus Bacillus and is named Bacillus sp. AS3, whose registration number on GenBank is ON890397. The two strains were able to degrade 17 dioxin isomers with the efficiency from 1.47% to 100% after 30 days depending on the isomer type. Total toxicity in culture samples of 2 strains AS2 and AS3 decreased by 71.83% and 41.73%, respectively, with total initial toxicity of 3000 pg/ml. The AS2 and AS3 strains degraded 2,4-D with an efficiency of 68.61% and 52.32%, respectively, with an initial concentration of 200 ppm. Also with this concentration, the two strains degraded 2,4,5-T with the rates of 72.14% and 59.73%.