title: Autotrophic hydrogen photoproduction by operation of carbon-concentrating mechanism in Chlamydomonas reinhardtii under sulfur deprivation condition.
abstract: Under autotrophic conditions, starch plays an important role in establishing anoxic conditions during PSII-dependent hydrogen (H2) photoproduction in microalgae. This is because starch is the sole organic substrate during respiratory consumption of internal oxygen (O2) from PSII-dependent direct pathway. Herein, we propose a novel approach to further facilitate the internal starch synthesis of Chlamydomonas reinhardtii through the operation of carbon-concentrating mechanism (CCM) along with a two-stage process based on sulfur (S) deprivation, thereby resulting in enhanced anaerobic capacity during PSII-dependent H2 photoproduction. When CCM-induced cells were exposed to high levels of carbon dioxide (CO2) (5%, v/v) with S deprivation, internal levels of starch were significantly elevated by retaining a functional CCM with the boosted photosynthetic activity during 24h of O2 evolution phase (I) of S deprivation. Consequently, during H2 production phase of S deprivation at irradiance of 50μEm(-2)s(-1), the concentrations of starch and H2 in CCM-induced cells were remarkably enhanced by 65.0% and 218.9% compared to that of CCM-uninduced cells, respectively. The treatment of low-CO2-driven CCM induction prior to S deprivation is a cost-effective and energy-efficient strategy that significantly improves the solar-driven H2 production by microalgae; this is particularly realizable in an industrial scale.
authors.affiliation: Department of Chemical Engineering, Sungkyunkwan University, Suwon 440-746, South Korea.
authors.forename: Min Eui
authors.initials: ME
authors.lastname: Hong
authors.affiliation: Department of Chemical and Biological Engineering, Korea University, Seoul 136-713, South Korea.
authors.forename: Ye Sol
authors.initials: YS
authors.lastname: Shin
authors.affiliation: Department of Chemical Engineering, Sungkyunkwan University, Suwon 440-746, South Korea.
authors.forename: Byung Woo
authors.initials: BW
authors.lastname: Kim
authors.affiliation: Department of Chemical and Biological Engineering, Korea University, Seoul 136-713, South Korea; Green School, Korea University, Seoul 136-713, South Korea. Electronic address: simsj@korea.ac.kr.
authors.forename: Sang Jun
authors.initials: SJ
authors.lastname: Sim
mesh_terms: D052818:Autotrophic Processes; D002244:Carbon / Q000378:metabolism*; D016825:Chlamydomonas reinhardtii / Q000254:growth & development* / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D010788:Photosynthesis; D013312:Stress, Physiological; D013455:Sulfur / Q000378:metabolism
chemical_list: D013455:Sulfur; D002244:Carbon; D006859:Hydrogen
keywords: Autotrophic H(2) photoproduction; CCM induction; Chlamydomonas reinhardtii; S deprivation; Starch accumulation