Heavy metals in the environment are a serious health risk to any living organism. Originating from car emissions, mining activities or wrongly disposed batteries, these non-biodgradable pollutants accumulate. Scientists from Croatia, Germany and Austria investigated the effect of relevant concentrations of Cadmium on earth worm gut microbiota. They found that prolonged exposure to Cadmium-supplemented soil leads to significant changes of bacteria composition in earth worm guts. A worrying finding; and an indication of what Cadmium does once it enters the food chain.
Because certain microbial species showed higher abundance in Cd-treated vs. control individuals, the authors proposed usage as biomarkers for environmental monitoring. In other words, from the composition of earthworm guts it will be possible to deduce the contamination level of the sampling site. The finding that several species accumulating in Cd-exposed worms were related to representatives of already known heavy metal-resistant or heavy metal-binding bacteria opens new opportunities: Earth worms and their microbiomes might be explored as a tool for soil remediation.
Srut M, Menke S, Hockner M, Sommer S. 2019. Earthworms and cadmium – Heavy metal resistant gut bacteria as indicators for heavy metal pollution in soils? Ecotoxicol Environ Saf 171: 843-853.