Bioremediation of γ-HCH-polluted field soil by inoculation with an aerobic γ-HCH-decomposing bacterium (Sphingomonas Paucimobilis SS86)

Abstract

Bioremediation of γ-HCH-polluted soil by inoculation of an aerobic γ-HCH-decomposing bacterium, Sphingomonas paucimobilis SS86, was attempted in a small scale experimental upland field where the tests were started in three different seasons. Decomposition of more than 95% of the initial concentration (6–9 μg g-1 soil) of γ-HCH was accomplished within 2 months after bacterial inoculation in August or October, and within 6 months in February. Fate of the bacterium at the site of inoculation varied among the three tests, being affected by the soil temperature. However, laboratory experiments indicated that the fate could be predicted by laboratory soil microcosm studies designed appropriately. During the winter season at low soil temperatures, SS86 bacterium survived almost constantly based on the number and it appeared to be free from association with soil aggregates and/or particles due to the low activities of grazing protozoa. These findings imply that the bacterium was transferred out of the site of inoculation by the movement of soil water. Based on the high γ-HCH-decomposing ability and detailed characterization of the behaviour in soil, S. paucimobilis SS86 is considered to be a suitable candidate for the bioremediation of γ-HCH-polluted field soil. © 1996, Taylor and Francis Group, LLC.