Toxicity biosensor for the evaluation of cadmium toxicity based on photosynthetic behavior of cyanobacteria Anabaean torulosa

Abstract

A biosensor based on electrochemical transduction using an oxygen probe has been develope for the measurement of Cd2+ toxicity by using cyanobacteria (Anabaena torulosa), where the cells were immobilized on the surface of an oxygen probe. The biosensor responded to the changes in photosynthetic oxygen release under illumination by a light source. Exposure to Cd2+ at concentrations below approximately 8 mg L-1 did not demonstrate any inhibition but stimulation of oxygen production was observed. Inhibition occurred only when concentration of Cd-2+ was above 8 mg L-1. Using the same concentration range of Cd2+ but increasing the exposure time of Cd2+ from 15 to 30 min, inhibition of oxygen release was mainly observed. This pattern of inhibition of A. torulosa by Cd2+ was different from that of Cu2+, which was also measured by the same toxicity biosensor, where no stimulation in oxygen release was observed. The use of toxicity biosensor has enabled the detail toxicity behaviour of A. torulosa towards Cd2+ to be evaluated. © 2008 Academic Journals Inc.