Abstract
In the purple bacterium Rhodovulum sulfidophilum, spheroidene monooxygenase (CrtA) converts spheroidene (yellow) to spheroidenone (red). Purpose of this study is to establish the whole cell biosensor system for environmental monitoring with low-cost using the color change evoked by CrtA in R. sulfidophilum.
An arsenite or dimethyl sulphide (DMS) sensor has a CrtA gene under regulation of the ars operator/promoter region and ArsR from E. coli or under regulation of the intrinsic DMS dehydrogenase gene promoter. Using the sensor strain, 0.6-6 μg/l arsenite or 3-30 μM DMS could be detected without adding any color-forming reagent. An increase in a molar ratio of spheroidenone and a shift in the color coordinate from a yellow to a red hue were observed, as the analyte concentration was raised. These results show that the genetically engineered R. sulfidophilum cells can be used to monitor quality of water environments by the naked eyes.
