Open AccessA fungus‐type β‐galactofuranan in the cultivated Trebouxia photobiont of the lichen Ramalina gracilis
Author(s) -
Cordeiro Lucimara M.C.,
Carbonero Elaine R.,
Sassaki Guilherme L.,
Reis Rodrigo A.,
StockerWörgötter Elfriede,
Gorin Philip A.J.,
Iacomini Marcello
Publication year - 2005
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1016/j.femsle.2005.01.040
Subject(s) - thallus , lichen , polysaccharide , botany , biology , fungus , galactomannan , cell wall , chemistry , biochemistry
A structural characterization of polysaccharides extracted from the aposymbiotically cultured photobiont of the lichen Ramalina gracilis was carried out in order to compare them with those previously found in the symbiotic thallus. The photobiont was isolated from thallus fragments, following the method of Yamamoto, and cultivated in a liquid nutrient medium. Freeze‐dried cells were defatted, and the polysaccharides extracted successively with water and aq. 10% KOH, each at 100 °C. After purification, the soluble fractions provided a polysaccharide containing a (1 ? 5)‐linked β‐galactofuranosyl backbone, substituted in a small proportion at O‐6 by β‐Gal f units. Amylose was also found, as insoluble material obtained on freeze‐thawing of the alkaline extract. These polysaccharides have not been found in the symbiotic thallus of Ramalina gracilis , which contained only water‐soluble (isolichenan) and insoluble glucans (nigeran and laminaran), and galactomannan. Surprisingly, the galactofuranan has similarities with those found in some fungal cell walls.