Microbial inoculation of Tagetes erecta in a phytoremediation system to enhance arsenic and cadmium removal from polluted soils

Abstract

In the presented research, a phytoremediation system was established by the inoculation of heavy metal resistant microorganisms isolated from the Mexican volcanic area of Los Azufres, Michoacán into the Mexican ornamental flower Tagetes erecta; with the final purpose of enhancing their individual bioremediation capacities when combined for their application in ex situ bioremediation of soils polluted with arsenic and cadmium. The methodology consisted of three main steps: the microbial isolation and characterization, the in vitro system establishment between the isolated microbes and the selected plant species to evaluate their interaction, and the creation of microcosms to evaluate their potential for ex situ bioremediation use. The results suggest that our isolated microbes, determined as LA1 & LA2, are heavy metal resistant, with a respective MIC of 1800 ppm of As and 250 ppm of As and Cd each; and that LA2 favors the development of Tagetes erecta in a medium supplemented with these heavy metals and enhances the plant's tolerance. This signifies an intriguing option to use as a phytoremediation system for ex situ bioremediation of soils polluted with arsenic and cadmium.