Lead is a toxic metal with detrimental effects on human development and is found in numerous contaminated industrial sites . Removal of toxic metals from contaminated sites is problematic and costly. Phytoremediation, the use of plants to remove toxins from the soil is one potential solution.
A group of Chinese scientists* explored adding an insect component to phytoremediation of sites contaminated by lead. Mulberry trees planted in lead contaminated soils removed lead from the soil. The majority of the lead was bound in the root tissue, but some lead was translocated to the leaves. Lead in mulberry leaves is primarily bound to cell walls.
Mulberry leaves can be fed to silkworms as part of the silk production process. The scientists found that silkworms are lead tolerant and can survive on contaminated leaves. Much of the lead consumed by silkworms is passed in the frass without being absorbed by the gut. Absorbed lead stimulates production of metallothioneins, detoxification enzymes that bind to lead and transport it into the urine for elimination.
Potentially, the mulberry could be planted on lead contaminated soil, fed to silkworms, and the frass with concentrated lead collected for proper disposal.
*Lingyun Zhou, Ye Zhao, Shuifeng Wang, Shasha Han, Jing Liu. 2015. Lead in the soil–mulberry–silkworm food chain: Translocation and detoxification. Chemosphere. 128: 171-177. http://dx.doi.org/10.1016/j.chemosphere.2015.01.031