The Study On The Optimization And Application Of Increased Photobiological H₂Production By NaHSO₃Treatment Strategy In Microalgae

With increasing environmental pollution and energy crisis, how to explore cleanand alternate energy source becomes more and more urgent. Photobiologicalhydrogen production by microalgae has become one of hot issues in energy fieldbecause of its clean and carbon-free renewable source. Photobiological H2productionis catalyzed by either nitrogenase or hydrogenase enzymes only within anaerobicenvironments. This rigorous condition for H2production greatly limits the industrialapplication of photobiological H2production in microalge.Despite treatment with NaHSO₃can induce a200-fold increase in H2photoproduction in Chlamydomonas reinhardtii, it still can not meet the industrialapplication of photobiological H2production. Therefore, one of our aims in this studyattempts to further enhance the photobiological H2production in microalgae treatedby NaHSO₃and to develop toward the industrial application. Our results showed thatstepwise NaHSO₃addition mode can significantly increase photobiological H2production （150%increase） in C. reinhardtii; this increase is mostly the result ofincreased the activity of PSII under anaerobic conditions.Furhter, despite treatment with NaHSO₃can strongly enhance H2photoproduction in Anabaena sp. strain PCC7120and C. reinhardtii, little is knownregarding whether this strategy is also applicable to other microalga for enhanced H2photoproduction? Thus, another aims of this study is to investigate whether thisstrategy can extensively enhance the yield of H2photoproduction in microalgae. Theexperimental findings showed that treatment with moderate concentration of NaHSO₃can greatly enhance the photobiological H2production in non-nitrogen-fixingcyanobacteria, nitrogen-fixing cyanobacteria, green algae and hydrogen high-yieldedmutants. The increase was most probably caused by reduced O2content in the culturesand enhanced hydrogenase activity. We therefore conclude that this thesis furtheroptimize the yield of H2photoproduction by NaHSO₃treatment and provide atheoretical reference for industrial application of photobiological H2production.