A simple water toxicity test using Photobcicterium leiognathi

An alternative assay for the rapid, sensitive, and cost-effective evaluation of the toxicity of selected chemicals has been developed, using 6.0 mm filter paper discs of immobilised cultures of the luminous marine bacterium, Photobacterium leiognathi. This method, which can visually detect minute amounts of toxic chemicals in water, can be performed as a class experiment or an individual student investigation to explain the concept of chemically induced cellular toxicity. Students rank the toxicity of selected organic and inorganic chemicals based on the chemical concentration (ppm) that will cause complete visual inhibition of luminescence over a period of time. This method will find important applications in the comparative determination of the antimicrobial property of various chemical preparations and, also, for the detection of minute amount of toxicants in water. Water samples can be collected from different sources, such as drinking water, rivers, lakes, and seas and tested by students themselves for biomonitoring purposes.