Optical biosensor based on the microalga-paramecium symbiosis for improved marine monitoring

Abstract

Unprecedented increases in anthropogenic pollution of marine environments have made the development of sensitive, cheap, and adaptable early-warning systems absolutely crucial for on-site monitoring of chemical contaminants. Biosensors based on microalgae cells might constitute a promising and cost-effective alternative for environmental analyses since they capable of providing rapid toxicity information in the case of pollution, while assessing the harmful effects of the contaminants on the ecosystem.In this work, an optical biosensor, based on an array of algal biomediators, has been developed to monitor relevant marine pollutants. A pre-study was performed to select the most suitable biomediator for measurements of pesticides in marine water. The potential of the algae-protozoa symbiotic association between Chlorella vulgaris and the ciliate Tetrahymena pyriformis as a sensitive biomediator for biosensor development was assessed, showing enhanced resistance to marine water salinity compared to free-living algae strains. The symbiotic strain was entrapped in calcium-alginate within newly developed fluidic flow cells with integrated detectors for real-time detection of marine pollutants by fluorescence analysis of photosynthetic photosystem II. The biosensor response was examined in the presence of three commonly found pesticides—simazine, atrazine and diuron—alone or in combination, and the results were compared by liquid chromatography-mass spectrometry. The limits of detection for the three herbicides were 1.35, 0.44, and 0.25 μg/L respectively, and 0.13 μg/L for the mixture.In summary, an autonomous integrated symbiotic association of paramecium-chlorella-based biosensor was successfully developed for real-time monitoring of marine water and evaluation of biotoxicity.