Simultaneous bioremediation of Cr(VI) and lindane in soil by actinobacteria

Abstract

Environments co-contaminated with metals and organic compounds are difficult to remediate. Actinobacteria is an important group of microorganisms found in soils, with high metabolic versatility and potential for bioremediation. In this paper, actinobacteria were used to remediate soil co-contaminated with Cr(VI) and lindane. Five actinobacteria, tolerant to Cr(VI) and lindane mixture were selected: Streptomyces spp. A5, A11, M7, and MC1 and Amycolatopsis tucumanensis DSM 45259. Sterilized soil samples were inoculated with actinobacteria strains, either individually or as a consortium and contaminated with Cr(VI) and lindane, either immediately or after 7 days of growth, and incubated at 30 ºC during 14 days. All actinobacteria were able to grow and remove both contaminants, the consortium formed by Streptomyces spp. A5, M7, MC1 and A. tucumanensis showed the highest Cr(VI) removal, while Streptomyces sp. M7 produced the maximum lindane removal. In non-sterile soil samples, Streptomyces sp. M7 and the consortium removed more than 40% of the lindane, while Streptomyces sp. M7 demonstrated the greatest Cr(VI) removal. The most appropriate strategy for bioremediation of Cr(VI) and lindane co-contaminated soils would be the inoculation with Streptomyces sp. M7. These results represent the first report on successful bioremediation of soils contaminated simultaneously with Cr(VI) and lindane.