Thermochemical studies of the toxic action of heavy metal ions onEscherichia coli by microcalorimetry

Abstract

By using an LKB2277, BioActivity Monitor (heat conduction microcalorimeter), stopped-flow method, the thermogenetic curves of Escherichia coli growth at 37°C inhibited by four kinds of heavy metal ions are determined, and parameters such as growth rate constants, inhibitory ratio, half-inhibitory concentration etc. were obtained. The experimental results show that heavy metal ions can inhibit Escherichia coli growth obviously, but low concentration of Cu²⁺ has a promoting action. The half inhibitory concentrations of Zn²⁺, Cd²⁺, Hg²⁺ and Cu²⁺ are 28.3, 10.9, 3.19 and 69.6 μg. mL⁻¹, respectively. Judged from the rate constant, the half-inhibitory concentration and the molecular mass, the inhibitory sequence is Hg²⁺>Cd²⁺>Zn²⁺>Cu²⁺. This microclorimetric bioassay for acute cellular toxicity is based on metabolic heat evolution from cultured cells. The assay is quantitative, inexpensive, and versatile; moreover, toxicological information can be obtained with cell from other species of interest.

Keywords

microcalorimetry / toxicity measurement / heavy metal ions

References

[1] McGulnness S M, Barisas B G. Acute Toxicity Measurements on Aquatic Pollutants Using Microcalorimetry on Tissue—cultured Cells. Environ. Sci. Technol., 1991, 25(6): 1092-1098.

[2] Buikema A L, Niederlehner B R, Cairns J. Biological Monitoring. Part IV. Toxicity Testing. Water Research, 1982, 16(3): 239-262.

[3] Weppen P, Schuller D. Microcalorimetric Studies of the Mode of Action of Environmental Chemicals on Continueous Microbial Cultures. Thermochimica Acta, 1984, 72: 95-102.

[4] Buckion G, Russell S J, Beezer A E. Pharmaceutical Calorimetry: A Selective Review. Thermochim. Acta, 1991, 193: 195-214.

[5] Xi Li, Yi Liu, Jun Wu, . Microcalorimetric Study of Escherichia coli Growth Inhibited by the Selenomorpholine Complexes. Biological Trace Element Research, 2000, 75: 167-175.

[6] Xi Li, Yi Liu, Jun Wu, . The Effect of the Selenomorpholine Derivatives on the Growth of S Aureus Studied by Microcalorimetry. Thermochimica Acta, 2001, 375(1–2): 109-113.

[7] Yi Liu, Xi Li, Songsheng Qu, . Microcalorimetric Investigation of the Toxic Action of Cd²⁺ on Rhizopus Nigricans Growth. J. Biochem. Biophys. Methods, 2000, 45: 231-239.

[8] Suurkuusk J, Wadso I. Amultichannel Microcalorimetry System. Chem. Scr., 1982, 20: 155-163.

[9] Yi Liu. Thermochemical Studies of Metabolic Characteristics of Bacteria and Mitochondria, 1997, Wuhan, the People’s Republic of China: Wuhan University.

[10] Wuhan University and Fudan University Microbiology, 1979, Beijing: People’s Education Press. 124-124.

[11] Beezer A E. From Guinea Pigs to Cutting Fluids-A Microcalorimetric Journey. Thermochimica Acta, 2000, 349: 1-7.