Open AccessLinear β‐mannose‐containing polysaccharide, β‐xylan, and amylose from the cultured photobiont Trebouxia sp. of the ascolichen Ramalina celastri
Author(s) -
Cordeiro Lucimara M.C,
Reis Rodrigo A,
Tischer Cesar A,
Gorin Philip A.J,
Ferreira Julio C,
Iacomini Marcello
Publication year - 2003
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/s0378-1097(03)00066-1
Subject(s) - amylose , polysaccharide , aqueous solution , mannan , chemistry , mannose , yield (engineering) , xylan , nuclear chemistry , starch , organic chemistry , materials science , metallurgy
The cultured photobiont Trebouxia sp. of Ramalina celastri was successively extracted at 100°C with hot water, 2% aqueous KOH, and 10% aqueous KOH to give polysaccharide‐containing fractions A (2.9%), B (3.9%), and C (0.9% yield) respectively. The intact biont contained 3.8% amylose, which was present in each fraction, and was identified by a blue color formed with iodine solution. In fraction A, and following retrogradation from aqueous solution, it was characterized by 13 C‐NMR spectroscopy. Fraction B was treated with α‐amylase to give a water‐soluble fraction consisting mainly of β‐mannose‐containing polysaccharides (1.5% yield), whose main component had d n /d c 0.162 and M r 17 kDa. Fraction C was subjected to freeze–thawing and the precipitate was treated with α‐amylase to give a resistant, linear, low molecular mass (1→4)‐linked β‐xylan. The β‐ d ‐mannopyranan preparation contained mainly of 3‐O‐ (28%), 4‐O‐ (11%), and 6‐O‐substituted Man p units (35%), with 3‐O‐substituted Rha p units (11%). A controlled Smith degradation provided a β‐mannan with nonreducing end‐ (8%), 3‐O‐ (85%) and 6‐O‐substituted units, showing (1→3)‐ and (1→6)‐linked structures in the original polysaccharide. These could be present as block‐type structures.