No abstract

Conservation of water resources calls for ever stricter regulatory measures and better monitoring systems. Whole-cell bacterial sensors have been genetically engineered to react to target toxicants by the induction of a selected promoter and the subsequent production of bioluminescent light through a recombinant lux reporter. In order to create a one-step assay, we have designed a new, self-contained, disposable optical fiber sensor module and a customized photodetector system that integrates these microorganisms. A photon-counting photomultiplier tube-based instrument was constructed. Optical fiber tip cores were covered with adlayer films consisting of calcium alginate containing bioluminescent bacterial sensors of genotoxicants. Multiplying these steps thickened the adlayer in increments, increasing the number of bacterial reporters attached to the optical fiber transducer. These whole cell optrodes are responsive to external traces of DNA damaging agents such as mitomycin C. Light production was shown to be dose-dependent and proportional to the number of bacterial layers.

A chemiluminescent-based optical fiber immunosensor was developed for the detection of antipneumococcal antibodies. This was accomplished by developing a different chemical procedure utilizing 3-aminopropyl trimethoxysilane and cyanuric chloride to conjugate pneumococcal cell wall polysaccharides to the optical fiber tips, and by improving the sensitivity of the photodetection system. The lowest titer of antipneumococcal antibodies detected by the optical fiber was at a 1:819,200 dilution. The lowest corresponding value by standard enzyme-linked immunosorbent assay was at a 1:98,415 dilution. It was concluded that the optical immunosensor system is an accurate and sensitive method to detect antipneumococcal antibodies and may be an adequate tool to monitor antibodies in specimens such as saliva and urine.