Une nouvelle méthode de criblage pour des muatnts sans hydrogénase chez Chlamydomonas reinhardtii, basé sur la fluorescence de la chlorophylle in vivo et sur le rendement photochimique du PSII

In Chlamydomonas reinhardtii, prolonged anaerobiosis leads to the expression of enzymes Received 30 August 2012 belonging to various fermentative pathways. Among them, oxygen-sensitive hydrogenases Received in revised form (HydA1/2) catalyze the synthesis of molecular hydrogen from protons and reduced ferre- 12 November 2012 doxin in the stroma. In this work, by analyzing wild type and mutants affected in H2 Accepted 16 November 2012 production, we show that maximal PSII photosynthetic electron transfer during the first Available online 21 December 2012 seconds of illumination after a prolonged dark-anaerobiosis period is linearly related to hydrogenase capacity. Based on the specific chlorophyll fluorescence induction kinetics Keywords: typical of hydrogenase-deficient mutants, we set up an in vivo fluorescence imaging Chlamydomonas reinhardtii screening protocol allowing to isolate mutants impaired in hydrogenase expression or Anaerobic photosynthesis activity, as well as mutants altered in related metabolic pathways required for energy Hydrogenase production in anaerobiosis. Compared to previously described screens for mutants Chlorophyll fluorescence impaired in H2 production, our screening method is remarkably fast, sensitive and non- Microalgae invasive. Out of 3000 clones from a small-sized insertional mutant library, five mutants Hydrogen photoproduction were isolated and the most affected one was analyzed and shown to be defective for the hydrogenase HydG assembly factor