Production and characterization of Chlamydomonas mutants for optical and electrochemical bio-sensing.

Photosynthetic microalgae are among the most preferred microorganisms for environmental monitoring and screening of food and agricultural products for hazards compounds. The unique features and structural constituents of the photosynthetic systems make them a suitable sensing element, largely due to their ability to conduct charge separation and electron transfer sensitive to the presence of different classes of pesticides, heavy metals, some drugs and explosive compounds. This research presents strategies for production and characterization of mutants of Chlamydomonas reinhardtii suitable as stable and sensitive bio-recognition elements in the optical and electrochemical sensing of herbicides. Novel bio-sensing elements with enhanced stability and tolerance to free-radicals-associated stress were generated by an in vitro directed evolution strategy targeted at the D1 protein of the photosystem II reaction center of C. reinhardtii using exposures to ionizing radiation as selection pressure [1]. In parallel, computational methods were exploited to identify single aminoacidic substitutions in the D1 protein conferring an increased affinity to the herbicide atrazine [2] and prove of concept was achieved by studies on de novo generated D1-site-directed mutants. This work was supported by COST Action TD1102 and Lazio project FACILE, contract n. 85-2017-15256.