Co-contaminated soils bioremediation by actinobacteria

Abstract

More than one third of contaminated areas are found to have more than one type of pollutant. Co-contaminated environments with metals and organic compounds are difficult to remediate because the mixed nature of the pollulants. Actinobacteria is an important group of microorganisms found in soils, with high metabolic versatility and abilities to bioremediation. Actinobacteria are currently studied for bioremediate soils contaminated by pesticides and heavy metals. In this chapter we reviewed the potential of actinobacteria isolated from contaminated environments for simultaneous soil bioremediation of Cr (VI) and the organochlorine pesticide lindane. Five actinobacteria, tolerant to Cr(VI) and lindane mixture were used: 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 (formed by all selected actinobacteria) then contaminated with Cr(VI) and lindane, 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. According to these results, it could be concluded that the use of Streptomyces sp. M7 is the strategy more appropriate for the bioremediation of soils contaminated with Cr (VI) and lindane.