title: Hydrogen photoproduction in green algae Chlamydomonas reinhardtii sustainable over 2 weeks with the original cell culture without supply of fresh cells nor exchange of the whole culture medium.
abstract: Unicellular green algae Chlamydomonas reinhardtii are known to make hydrogen photoproduction under the anaerobic condition with water molecules as the hydrogen source. Since the hydrogen photoproduction occurs for a cell to circumvent crisis of its survival, it is only temporary. It is a challenge to realize persistent hydrogen production because the cells must withstand stressful conditions to survive with alternation of generations in the cell culture. In this paper, we have found a simple and cost-effective method to sustain the hydrogen production over 14 days in the original culture, without supply of fresh cells nor exchange of the culture medium. This is achieved for the cells under hydrogen production in a sulfur-deprived culture solution on the {anaerobic, intense light} condition in a desiccator, by periodically providing a short period of the recovery time (2 h) with a small amount of TAP(+S) supplied outside of the desiccator. As this operation is repeated, the response time of transition into hydrogen production (preparation time) is shortened and the rate of hydrogen production (build up time) is increased. The optimum states of these properties favorable to the hydrogen production are attained in a few days and stably sustained for more than 10 days. Since generations are alternated during this consecutive hydrogen production experiment, it is suggested that the improved hydrogen production properties are inherited to next generations without genetic mutation. The properties are reset only when the cells are placed on the {sulfur-sufficient, aerobic, moderate light} conditions for a long time (more than 1 day at least).
authors.affiliation: Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Yagi
authors.affiliation: Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan.
authors.forename: Kyohei
authors.initials: K
authors.lastname: Yamashita
authors.affiliation: Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan.
authors.forename: Norihide
authors.initials: N
authors.lastname: Okada
authors.affiliation: Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Isono
authors.affiliation: Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Momose
authors.affiliation: Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba-ken, 278-8510, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Mineki
authors.affiliation: Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan. eiji@rs.kagu.tus.ac.jp.
authors.forename: Eiji
authors.initials: E
authors.lastname: Tokunaga
mesh_terms: D018929:Cell Culture Techniques / Q000379:methods*; D016825:Chlamydomonas reinhardtii / Q000378:metabolism* / Q000528:radiation effects*; D003470:Culture Media / Q000494:pharmacology*; D006859:Hydrogen / Q000378:metabolism*; D008027:Light; D013057:Spectrum Analysis; D013455:Sulfur / Q000494:pharmacology; D013997:Time Factors
chemical_list: D003470:Culture Media; D013455:Sulfur; D006859:Hydrogen
keywords: Anaerobic condition; Chlamydomonas reinhardtii; Green algae; Hydrogen photoproduction; Non-genetic inheritance; Sulfur deprivation