title: Phenotypic diversity of hydrogen production in chlorophycean algae reflects distinct anaerobic metabolisms.
abstract: Several species of green algae use [FeFe]-hydrogenases to oxidize and/or produce H(2) during anoxia. To further define unique aspects of algal hydrogenase activity, the well-studied anaerobic metabolisms of Chlamydomonas reinhardtii were compared with four strains of Chlamydomonas moewusii and a Lobochlamys culleus strain. In vivo and in vitro hydrogenase activity, starch accumulation/degradation, and anaerobic end product secretion were analyzed. The C. moewusii strains showed the most rapid induction of hydrogenase activity, congruent with high rates of starch catabolism, and anoxic metabolite accumulation. Intriguingly, we observed significant differences in morphology and hydrogenase activity in the C. moewusii strains examined, likely the result of long-term adaptation and/or genetic drift during culture maintenance. Of the C. moewusii strains examined, SAG 24.91 showed the highest in vitro hydrogenase activity. However, SAG 24.91 produced little H(2) under conditions of sulfur limitation, which is likely a consequence of its inability to utilize exogenous acetate. In L. culleus, hydrogenase activity was minimal unless pulsed light was used to induce significant H(2) photoproduction. Overall, our results demonstrate that unique anaerobic acclimation strategies have evolved in distinct green algae, resulting in differential levels of hydrogenase activity and species-specific patterns of NADH reoxidation during anoxia.
authors.affiliation: Division of Environmental Science and Engineering, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401, USA.
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Meuser
authors.forename: Gennady
authors.initials: G
authors.lastname: Ananyev
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Wittig
authors.forename: Sergey
authors.initials: S
authors.lastname: Kosourov
authors.forename: Maria L
authors.initials: ML
authors.lastname: Ghirardi
authors.forename: Michael
authors.initials: M
authors.lastname: Seibert
authors.forename: G Charles
authors.initials: GC
authors.lastname: Dismukes
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Posewitz
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D000460:Chlorophyta / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism*; D006864:Hydrogenase / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D010788:Photosynthesis; D010802:Phylogeny; D013213:Starch / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism
chemical_list: D007506:Iron-Sulfur Proteins; D013455:Sulfur; D006859:Hydrogen; D013213:Starch; C118830:iron hydrogenase; D006864:Hydrogenase