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2B - Natural Stressors and Toxicants (TUP/63) Combined physicochemical and biological sensing to detect the effect of environmentally relevant anions on micro-organisms. Bhatia, Radhika1, Dilleen, John2, Atkinson, Anne3, Rawson, David4, 1 University of Luton, Luton, Bedfordshire, UK2 University of Luton, Luton, Bedfordshire, UK3 University of Luton, Luton, Bedfordshire, UK4 University of Luton, Luton, Bedfordshire, UK ABSTRACT- The natural environment is a constantly changing habitat and results in organisms experiencing varying combinations of multiple stressors. Methods of evaluating the impact of environmental stressors alongside chemical toxicity are therefore sought. Release of effluents in water bodies can lead to ion imbalance, which can be toxic to the aquatic microflora and fauna due to a change in the surrounding conductivity and osmolarity. A disposable conductivity sensor has been developed within LIRANS, which can detect any changes in the ionic strength of the solution in the vicinity of the electrode array. This sensor is compatible with the CellSense™ biosensor system, which is a mediated amperometric system used to detect changes in the metabolic status of the immobilised micro-organisms. This paper reports on the simultaneous monitoring of conductivity and microbial sensors to investigate the effect of both species (chloride and nitrate) and concentration/ osmolarity of the anions on the metabolic activity of immobilised micro-organisms [Escherichia coli and ammonia oxidising bacteria (AOB)]. The biosensors were also monitored in the presence and absence of toxicants 3,5-dichlorophenol and HgCl2. Both chloride and nitrate were found to be more toxic to the AOB than E. coli. It was observed that toxicity of the test toxicants depends not only on the presence or absence of different anions, but also the type of micro-organism being employed in the bioassay. The ability of water-borne anions to affect different types of microbial metabolism and their influence on micro-organism-toxicant interactions will be discussed. Key words: 3,5-dichlorophenol, microbial biosensor, mercuric chloride, ammonia oxidising bacteria |
