Simultaneous Cr(VI) and lindane removal by Streptomyces M7 is improved by maize root exudates

Abstract

Environmental mixed pollution by both organic and inorganic compounds aredetected worldwide. Phytoremediation techniques have been proposed as ecofriendlymethods for cleaning up polluted sites. Several studies have demonstrated enhanceddissipation of contaminants at the root-soil interface through an increase in microbialactivity caused by the release of plant root exudates (REs). The aim of this study wasto evaluate the effectiveness for Cr(VI) and lindane removal by Streptomyces M7cultured in a co-contaminated system in presence of maize REs. Our results showedwhen REs were added to the contaminated minimal medium (MM) as the only carbonsource, microbial removal of Cr(VI) and lindane increased significantly incomparison to contaminant removal obtained in MM with glucose 1 g L−1. Themaximum removal of 91% of lindane and 49.5% of Cr(VI) were obtained in theco-contaminated system. Moreover, Streptomyces M7 showed plant growthpromoting traits which could improve plant performance in contaminated soils.The results presented in this study provide evidence that maize REs improved growthof Streptomyces M7 when REs were used as a carbon source in comparison toglucose. Consequently, lindane and Cr(VI) removal was considerably enhancedmaking evident the phytoremediation potential of the actinobacteria-plantpartnership.