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2B - Natural stressors and toxicants (TU13/13) The influence of temperature on the sensitivity of microbes to toxicants. Wex, Hannah1, Zhang, Tiantian 1, Rawson, David1, 1 The University of Luton, Luton, Bedfordshire, United Kingdom ABSTRACT- Temperature is one of the most important abiotic factors affecting microbial sensitivity to toxicants. Changes in environmental temperature will influence the physiology and metabolic activity of microbes, and may reduce or enhance their ability to withstand the presence of additional stresses such as toxicants. However, little work has been done to investigate the interaction between temperature and toxicity. In this study the sensitivity of Escherichia coli to 3,5-Dichlorophenol, and mercuric chloride over the temperature range 15 to 35°C was investigated using the Cellsense™ mediated amperometric biosensor assay, and a growth assay. The sensitivity of a consortium of ammonia oxidising bacteria to the same toxicants over the temperature range 5 to 20°C was investigated using the biosensor assay. In both assays the sensitivity of E. coli to mercuric chloride increased with increasing temperature but the sensitivity of the cells to 3,5-Dichlorophenol decreased. The higher metabolic activity supported by the warmer temperatures may enable the E. coli to resist the effects of the narcotic compound more effectively than at 15°C. The sensitivity of the ammonia oxidising bacteria to both toxicants increased as the temperature increased from 10 to 20°C, but at 5°C was much higher than expected, with lower EC50 values than those of cells tested at 10 and 15°C. This high sensitivity at 5°C indicates that the ability of the bacteria to cope with toxicant stress is reduced at the lower extremes of their temperature range. The study shows that the significant effects of temperature on the sensitivity of microbes to toxicants vary with both test species and toxicant. Key words: toxicity, temperature, bacteria, biosensors |
