title: Bioenergetic changes in the microalgal photosynthetic apparatus by extremely high CO2 concentrations induce an intense biomass production.
abstract: Unicellular green alga Chlorella minutissima, grown under extreme carbon dioxide concentrations (0.036-100%), natural temperature and light intensities (Mediterranean conditions), strongly increase the microalgal biomass through photochemical and non-photochemical changes in the photosynthetic apparatus. Especially, CO(2) concentrations up to 10% enhance the density of active reaction centers (RC/CS(o)), decrease the antenna size per active reaction center (ABS/RC), decrease the dissipation energy (DI(o)/RC) and enhance the quantum yield of primary photochemistry (F(v)/F(m)). Higher CO(2) concentrations (20-25%) combine the above-mentioned photochemical changes with enhanced non-photochemical quenching of surplus energy, which leads to an enhanced steady-state fraction of 'open' (oxidized) PSII reaction centers (q(p)), and minimize the excitation pressure of PSII (1 - q(p)) under very high light intensities (approximately 1700 micromol m(-2) s(-1) maximal value), avoiding the photoinhibition and leading to an enormous biomass production (approximately 2500%). In conclusion, these extreme CO(2) concentrations - about 1000 times higher than the ambient one - can be easily metabolized from the unicellular green alga to biomass and can be used, on a local scale at least, for the future development of microalgal photobioreactors for the mitigation of the factory-produced carbon dioxide.
authors.affiliation: Department of Biology, University of Crete, PO Box 2208, 71409 Heraklion, Crete, Greece.
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Papazi
authors.forename: Pavlos
authors.initials: P
authors.lastname: Makridis
authors.forename: Pascal
authors.initials: P
authors.lastname: Divanach
authors.forename: Kiriakos
authors.initials: K
authors.lastname: Kotzabasis
mesh_terms: D018533:Biomass; D002245:Carbon Dioxide / Q000378:metabolism* / Q000494:pharmacology*; D002708:Chlorella / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects; D004734:Energy Metabolism / Q000187:drug effects; D007700:Kinetics; D008027:Light; D010788:Photosynthesis / Q000187:drug effects; D045332:Photosystem II Protein Complex / Q000378:metabolism
chemical_list: D045332:Photosystem II Protein Complex; D002245:Carbon Dioxide