SCREENING ALGAL MUTANT COLONIES WITH ALTERED THYLAKOID ELECTROCHEMICAL GRADIENT THROUGH FLUORESCENCE AND DELAYED LUMINESCENCE DIGITAL IMAGING

A digital imaging instrument intended to monitor fluorescence and dela yed luminescence of algal colonies grown on Petri plates is described. The system includes light-emitting diodes, a cooled line transfer cha rge-coupled device (CCD) camera, and a personal computer. Software dev elopments were made to capture pictures and kinetics in real time duri ng illuminations. This instrument makes the fluorescence induction kin etics of individual colonies readily accessible with a good time resol ution. It offers a great refinement for screening colonies deficient i n photosynthetic electron transfer thanks to appropriate computed fluo rescence images. The high sensitivity of the instrument allows it to c apture fluorescence images under non-actinic illuminations, and for th e first time, delayed luminescence images, opening thus the way to scr eening mutants that have altered thylakoid electrochemical gradients.