title: Desmodesmus sp. 3Dp86E-1-a novel symbiotic chlorophyte capable of growth on pure CO2.
abstract: A novel chlorophyte Desmodesmus sp. 3Dp86E-1 isolated from a White Sea hydroid Dynamena pumila was cultivated at CO2 levels from atmospheric (the 'low-CO2' conditions) to pure carbon dioxide (the 5, 20, and 100 % CO2 conditions) under high (480 μE/(m(2) s) PAR) light. After 7 days of cultivation, the '100 % CO2' (but not 5 or 20 % CO2) cells possessed ca. four times higher chlorophyll content per dry weight (DW) unit than the low-CO2 culture. The rate of CO2 fixation under 100 % CO2 comprised ca. 1.5 L/day per L culture volume. After a lag period which depended on the CO2 level, biomass accumulation and volumetric fatty acid (FA) content of the Desmodesmus sp. 3Dp86E-1 bubbled with CO2-enriched gas mixtures increased and was comparable to that of the culture continuously bubbled with air. Under the low-to-moderate CO2 conditions, the FA percentage of the algal cells increased (to 40 % DW) whereas under high-CO2 conditions, FA percentage did not exceed 15 % DW. A strong increase in oleate (18:1) proportion of total FA at the expense of linolenate (18:3) was recorded in the '100 % CO2' cells. Electron microscopy and pulse-amplitude-modulated chlorophyll fluorescence investigation revealed no damage to or significant downregulation of the photosynthetic apparatus in '100 % CO2' cells grown at the high-PAR irradiance. Possible mechanisms of high-CO2 tolerance of Desmodesmus sp. 3Dp86E-1 are discussed in view of its symbiotic origin and possible application for CO2 biomitigation.
authors.affiliation: Department of Bioengineering, Faculty of Biology, Lomonosov Moscow State University, 119234, GSP-1, Moscow, Russia, solovchenko@mail.bio.msu.ru.
authors.forename: Alexei
authors.initials: A
authors.lastname: Solovchenko
authors.forename: Olga
authors.initials: O
authors.lastname: Gorelova
authors.forename: Irina
authors.initials: I
authors.lastname: Selyakh
authors.forename: Larisa
authors.initials: L
authors.lastname: Semenova
authors.forename: Olga
authors.initials: O
authors.lastname: Chivkunova
authors.forename: Olga
authors.initials: O
authors.lastname: Baulina
authors.forename: Elena
authors.initials: E
authors.lastname: Lobakova
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology*; D000818:Animals; D018533:Biomass; D002245:Carbon Dioxide / Q000378:metabolism*; D000460:Chlorophyta / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure; D005227:Fatty Acids / Q000378:metabolism; D037402:Hydrozoa / Q000382:microbiology*; D046529:Microscopy, Electron, Transmission; D009792:Oceans and Seas; D012426:Russia; D013559:Symbiosis / Q000502:physiology*
chemical_list: D005227:Fatty Acids; D002245:Carbon Dioxide