Effect of the acclimation of a Streptomyces consortium on lindane biodegradation by free and immobilized cells

Abstract

Lindane is an organochlorine pesticide widely used in agriculture, human health, and veterinary. It is a persistent organic pollutant, representing a serious risk since its residues are still in the environment. The aim of this work was to evaluate the influence of the acclimation of free and immobilized Streptomyces consortium on lindane degradation in liquid and slurry systems. The actinobacteria consortium demonstrated stability since the survival of all members was confirmed after the acclimation period. It reached higher biomass (0.56-0.65 g L-1) and lindane removal (40-97%) than the consortium without acclimation (0.37-0.44 g L-1; 33-87%) when it was cultured in liquid medium with 20 and 50 mg L-1 of lindane. In contrast, lindane removal achieved by acclimated and immobilized consortium in slurry system (50%) did not present significant difference respect to the consortium without acclimation. Moreover, lindane degradation was confirmed by identification of three metabolites in liquid medium, 1,2- and 1,4-dichlorobenzene, and γ-pentachlorocyclohexene; and by determination of chloride ions released in slurry system. Bioassays with Lactuca sativa demonstrated the effectiveness of the bioremediation by the acclimated consortium in both systems, since the seedlings showed an improvement in its biological parameters compared to abiotic controls, confirming a significant decrease in toxicity.