title: Genome of an endosymbiont coupling N2 fixation to cellulolysis within protist cells in termite gut.
abstract: Termites harbor diverse symbiotic gut microorganisms, the majority of which are as yet uncultivable and their interrelationships unclear. Here, we present the complete genome sequence of the uncultured Bacteroidales endosymbiont of the cellulolytic protist Pseudotrichonympha grassii, which accounts for 70% of the bacterial cells in the gut of the termite Coptotermes formosanus. Functional annotation of the chromosome (1,114,206 base pairs) unveiled its ability to fix dinitrogen and recycle putative host nitrogen wastes for biosynthesis of diverse amino acids and cofactors, and import glucose and xylose as energy and carbon sources. Thus, nitrogen fixation and cellulolysis are coupled within the protist's cells. This highly evolved symbiotic system probably underlies the ability of the worldwide pest termites Coptotermes to use wood as their sole food.
authors.affiliation: Ecomolecular Biorecycling Science Research Team, RIKEN Advanced Science Institute, Saitama 351-0198, Japan. yhongo@riken.jp
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hongoh
authors.forename: Vineet K
authors.initials: VK
authors.lastname: Sharma
authors.forename: Tulika
authors.initials: T
authors.lastname: Prakash
authors.forename: Satoko
authors.initials: S
authors.lastname: Noda
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Toh
authors.forename: Todd D
authors.initials: TD
authors.lastname: Taylor
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kudo
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Sakaki
authors.forename: Atsushi
authors.initials: A
authors.lastname: Toyoda
authors.forename: Masahira
authors.initials: M
authors.lastname: Hattori
authors.forename: Moriya
authors.initials: M
authors.lastname: Ohkuma
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D041963:Bacteroidetes / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D002876:Chromosomes, Bacterial / Q000235:genetics; D004064:Digestive System / Q000378:metabolism / Q000382:microbiology / Q000469:parasitology; D056890:Eukaryota / Q000302:isolation & purification / Q000378:metabolism / Q000382:microbiology*; D005285:Fermentation; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D006019:Glycolysis; D020049:Isoptera / Q000378:metabolism / Q000382:microbiology* / Q000469:parasitology; D053858:Metabolic Networks and Pathways; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000378:metabolism; D009586:Nitrogen Fixation / Q000235:genetics; D010088:Oxidoreductases / Q000235:genetics; D010802:Phylogeny; D013559:Symbiosis; D014934:Wood / Q000378:metabolism
chemical_list: D000596:Amino Acids; D009005:Monosaccharides; D002482:Cellulose; D010088:Oxidoreductases; C029130:nitrogenase reductase