“…About one-half of the herbicides presently used in agriculture act by inhibiting the light reactions in photosynthesis, mostly by targeting the photosystem II (PSII) complex (10). A series of algal and cyanobacterial PSII-based whole-cell (5,6,11,14,27,28,34,37,43) and tissue (3,15,17,18,19,30,31,32) biosensors have therefore been developed for detection of a class of herbicides which inhibit photosynthetic electron transport. In these systems, herbicides are detected by testing inhibition of the Hill reaction (6,17,31,32), inhibition of 2,6-dichlorophenol indophenol photoreduction (4,5,15), or change in chlorophyll fluorescence (8,11,19,30), which can be correlated with the pollutant concentration.…”