Heavy metal induced biomolecule and genotoxic changes in earthworm Eisenia fetida

Abstract

A vibrational [Fourier transform infrared (FTIR)] spectroscopic method was used for the structural and compositional analysis of earthworm Eisenia fetida by monitoring of metal binding and further transformations in live cells. The FTIR analyses for metals taken up by the E. fetida will be useful for analyzing the impact of the heavy metal stress on the worm metabolism. The epigeic earthworm E. fetida were exposed to 100 %, 75 %, 50 %, 30 %, 25 %, 15 % and 5 % of dried automobile service station waste mud. All the earthworms exposed in the 100 %, 75 % and 50 % concentrations didn’t survived within 10days. Further experiments were conducted with 25 %, 15 % and 5 % concentration of wastes. Each concentration level was tested with three replicates using 10 animals and the metabolic response after exposure to the heavy metal containing service station waste mud was assessed by FTIR. Furthermore we also emphasized that DNA damage was confirmed with the use of other biomarker like comet assay. The peaks at 1045, 1080, 1236 cm−1 and 1650 cm−1 represented the overall susceptibility of nucleotides, phospholipids, DNA and RNA. Nucleic acids and proteins were modified due to heavy metal accumulation. In flow-through, single cell gel electrophoresis revealed the degradation nuclear DNA. Heavy metals accumulation in the worms was measured and it was found that lead, zinc and copper accumulation increased in the treatment group. Without the use of biomarkers for identifying ecological risks of land contamination, traditional assessment would be difficult to interpret. This new FTIR based biomolecules study revealed a clear molecule shift in the exposed worms, due to heavy metal accumulation.