title: Cellulose degradation and assimilation by the unicellular phototrophic eukaryote Chlamydomonas reinhardtii.
abstract: Plants convert sunlight to biomass, which is primarily composed of lignocellulose, the most abundant natural biopolymer and a potential feedstock for fuel and chemical production. Cellulose assimilation has so far only been described for heterotrophic organisms that rely on photosynthetically active primary producers of organic compounds. Among phototrophs, the unicellular green microalga Chlamydomonas reinhardtii is widely known as one of the best established model organisms. It occupies many habitats, including aquatic and soil ecosystems. This ubiquity underscores the versatile metabolic properties of this microorganism. Here we present yet another paradigm of adaptation for C. reinhardtii, highlighting its photoheterotrophic ability to utilize cellulose for growth in the absence of other carbon sources. When grown under CO(2)-limiting conditions in the light, secretion of endo-β-1,4-glucanases by the cell causes digestion of exogenous cellulose, followed by cellobiose uptake and assimilation. Phototrophic microbes like C. reinhardtii may thus serve as biocatalysts for cellulosic biofuel production.
authors.affiliation: Department of Biology, Algae Biotechnology and Bioenergy-Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany.
authors.forename: Olga
authors.initials: O
authors.lastname: Blifernez-Klassen
authors.forename: Viktor
authors.initials: V
authors.lastname: Klassen
authors.forename: Anja
authors.initials: A
authors.lastname: Doebbe
authors.forename: Klaudia
authors.initials: K
authors.lastname: Kersting
authors.forename: Philipp
authors.initials: P
authors.lastname: Grimm
authors.forename: Lutz
authors.initials: L
authors.lastname: Wobbe
authors.forename: Olaf
authors.initials: O
authors.lastname: Kruse
mesh_terms: D002475:Cellobiose / Q000378:metabolism; D002480:Cellulase / Q000235:genetics / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism* / Q000494:pharmacology; D016825:Chlamydomonas reinhardtii / Q000166:cytology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D003224:Congo Red / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006868:Hydrolysis / Q000187:drug effects; D008954:Models, Biological; D010641:Phenotype; D052817:Phototrophic Processes / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D002475:Cellobiose; D003224:Congo Red; D002482:Cellulose; D002480:Cellulase