Toxic effect of hexavalent chromium with copper and zinc ions on the growth metabolism of Escherichia coli based on microcalorimetry and microbial biomass
Speciation of chromium has attracted a great deal of interest in view of the toxic properties of Cr (VI) as compared with the much less toxic Cr (III). Bacteria such as Escherichia coli (E. coli) are uniquely suitable for toxicity tests and E. coli has been utilized to study its growth responses to various chromium species in the presence of Cu<2+> and Zn<2+> by a multi-channe| thermal activity monitor at 37℃. Important parameters including the growth rate constant k, inhibitory ratio I, half- inhibitory concentration IC<,50> et al., were determined. The results showed that Cr (VI) and high concentrations of Cr (III) are toxic to E. coli;however, Cr (II) to E. coli had 10-fold smaller IC<,50> concentrations as compared with Cr (VI). Different types of metal interactions among chromium, copper, and zinc ions were observed. These interactions can be classified as synergistic, antagonistic and additive. They depend strictly on the oxidation state and the concentration of chromium ions in the environment.
Thermal activity monitor Escherichia coli chromium speciation heavy metal interactions
Jun Yao Lin Tian Chanqian Qu Fei Wang Yong Zhou Huilun Chen Yanxin Wang BaralkiewiczDanuta Brunello Ceccanti
School of Environmental Studies & Key Laboratory of Biogeology and Environmental Geology of Chinese School of Environmental Studies & Key Laboratory of Biogeology and Environmental Geology of Chinese Faculty of Chemistry, Adam Mickiewicz University, Collegium Chemicum ul. Grunwaldzka 6, 60780 Poznan Institute of Ecosystem Study, Research Unit of Pisa, National Council of Researches (CNR), Via Moruz