Individual and combined toxic effect of nickel and chromium on biochemical constituents in E. coli using FTIR spectroscopy and Principle component analysis.

Ni and Cr are ubiquitous pollutants in the aquatic environments. These heavy metals elicit toxicities to aquatic organisms including microbes. In this study, interaction of the two heavy metals on the toxicity in Escherichia coli (E. coli) was studied using FTIR spectroscopy. The binding of Ni(II) to E. coli was stronger than that for Cr(VI). Cr exhibited antagonistic effects in the presence of Ni in E. coli. FTIR analysis showed a decrease in lipid content in the presence of Ni and not for Cr. Further, a decrease in band area was observed in the region of 3000-2800cm(-1) and at ~1455cm(-1) due to a decrease in fatty acids and lipid molecules. The band area ratio of lipid was used to monitor the changes in fatty acids due to metal toxicity. Principle component method helps to discriminates the results between control and metal toxicities in E. coli from the FTIR data. The study shows the importance of metal interaction and its toxicity on E. coli.