title: Carbohydrate, glycolipid, and lipid components from the photobiont (Scytonema sp.) of the lichen, Dictyomema glabratum.
abstract: The photobiont of the lichen, Dictyonema glabratum (Scytonema sp.), was isolated and cultivated in a soil-extract medium and submitted to chemical analysis. Successive extractions with CHCl3-MeOH, aqueous MeOH, and H2O gave rise to solutions of lipids (25%), low-molecular-weight carbohydrates (22%), and polysaccharides (4%), respectively. TLC of the lipid extract showed the presence of glycolipids, which were further purified and examined by NMR spectroscopy and GC-MS. Monogalactosyldiacylglycerol (1%), digalactosyldiacylglycerol (0.8%), trigalactosyldiacylglycerol (0.4%), and sulfoquinovosyldiacylglycerol (0.5%) were identified. The most abundant fatty acid ester in each fraction was palmitic (C16:0), but a great variation of the ester composition from one to another was found. Others present were those of C12:0, C14:0, C15:0, C16:1, C17:0, C18:0, C18:1, C18:2, C18:3, C22:0, C22:2, and C24:0. The lipid extract was also subjected to acid methanolysis, which gave rise to dodecane, 2-Me-heptadecane, 2,6-Me2-octadecane, and 8-Me-octadecane, methyl esters of C14:0, C15:0, C16:0, C16:1, C17:0, C18:0, C18:1, C18:2, C20:0, and C24:0 fatty acids, and the dimethyl ester of decanedioic acid. The polysaccharide had mainly Glc, Gal, and Man, with small amounts of 3-O-methylrhamnose and 2-O-methylxylose, both found in plants, and unexpectedly, some of the units were beta-galactofuranose, typical of fungal, but not cyanobacterial polysaccharides. The low-molecular-weight carbohydrates showed mannose as the main free reducing sugar, which differs from Nostoc sp. and Trebouxia sp. photobionts.
authors.affiliation: Departamento de Bioquímica, Universidade Federal do Paraná, CP 19046, 81531-990, Curitiba-PR, Brazil. sassaki@ufpr.br
authors.forename: Guilherme L
authors.initials: GL
authors.lastname: Sassaki
authors.forename: Philip A J
authors.initials: PA
authors.lastname: Gorin
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Reis
authors.forename: Rodrigo V
authors.initials: RV
authors.lastname: Serrato
authors.forename: Selene L
authors.initials: SL
authors.lastname: Elífio
authors.forename: Marcello
authors.initials: M
authors.lastname: Iacomini
mesh_terms: D002241:Carbohydrates / Q000737:chemistry; D002855:Chromatography, Thin Layer; D003124:Colorimetry; D000458:Cyanobacteria / Q000378:metabolism*; D005227:Fatty Acids / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D006017:Glycolipids / Q000737:chemistry; D006838:Hydrocarbons / Q000737:chemistry; D008011:Lichens / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D011134:Polysaccharides / Q000737:chemistry; D011522:Protons; D012987:Soil
chemical_list: D002241:Carbohydrates; D005227:Fatty Acids; D006017:Glycolipids; D006838:Hydrocarbons; D008055:Lipids; D011134:Polysaccharides; D011522:Protons; D012987:Soil