A microbial biosensor for p-nitrophenol using Arthrobacter sp.

This article reports the construction, optimization of performance variables and analytical characterization of a sensitive and selective microbial amperometric biosensor for measurement of p-nitrophenol (PNP), a U.S. Environmental Agency priority pollutant. The biosensor consisted of PNP-degrading/oxidizing bacteria Arthrobacter sp. JS443 as biological sensing element and a dissolved oxygen electrode as the transducer. The best sensitivity and response time were obtained using a sensor constructed with 1.2 mg dry wt. of cells and operating in pH 7.5, 50 mM citrate-phosphate buffer. Using these conditions, the biosensor was able to measure as low as 28 ppb (0.2 muM) of PNP selectively without interference from structurally similar compounds, such as phenol, nitrophenols and chlorophenols. The service life of the microbial biosensor is around 5 days when stored in the operating buffer at 4degreesC. The applicability to lake water is demonstrated.