OPTICAL BIOSENSOR FOR ENVIRONMENTAL ONLINE MONITORING OF NAPHTHALENE AND SALICYLATE BIOAVAILABILITY WITH AN IMMOBILIZED BIOLUMINESCENT CATABOLIC REPORTER BACTERIUM

An optical whole-cell biosensor based on a genetically engineered biol uminescent catabolic reporter bacterium was developed for continuous o n-line monitoring of naphthalene and salicylate bioavailability and mi crobial catabolic activity potential in waste streams. The bioluminesc ent reporter bacterium, Pseudomonas fluorescens HK44, carries a transc riptional nahG-luxCDABE fusion for naphthalene and salicylate cataboli sm. Exposure to either compound resulted in inducible bioluminescence. The reporter culture was immobilized onto the surface of an optical l ight guide by using strontium alginate. This biosensor probe was then inserted into a measurement cell which simultaneously received the was te stream solution and a maintenance medium. Exposure under defined co nditions to both naphthalene and salicylate resulted in a rapid increa se in bioluminescence. The magnitude of the response and the response time were concentration dependent. Good reproducibility of the respons e was observed during repetitive perturbations with either naphthalene or salicylate. Exposure to other compounds, such as glucose and compl ex nutrient medium or toluene, resulted in either minor bioluminescenc e increases after significantly longer response times compared with na phthalene or no response, respectively. The environmental utility of t he biosensor was tested by using real pollutant mixtures. A specific b ioluminescence response was obtained after exposure to either an aqueo us solution saturated with JP-4 jet fuel or an aqueous leachate from a manufactured-gas plant soil, since naphthalene was present in both po llutant mixtures.