M. Manzoni et M. Rollini, Isolation and characterization of the exopolysaccharide produced by Daedalea quercina, BIOTECH LET, 23(18), 2001, pp. 1491-1497
The production of exopolysaccharide (EPS) by a strain of the basidiomycete
Daedalea quercina was investigated. Of seven different carbon sources, gluc
ose and dextrins gave the highest crude polysaccharide yield (4.7-5 g l(-1)
, 55-60% carbohydrate content) in shake-flask cultures, at 14 days of ferme
ntation. Experiments carried out in a 101 fermenter, at two different agita
tion speeds, gave the best results at 300 rpm, resulting in 12-14 g l(-1) o
f crude exopolysaccharide in 9-11 days. Fractionation of the EPS samples, c
arried out by tangential flow ultrafiltration, evidenced a single EPS fract
ion (MW > 30 000 Da) in samples from glucose, while two fractions (MW > 30
000 Da and 30 000 > MW > 10 000 Da) were present in samples from dextrins.
Fractions characterization by HPLC and proton NMR spectroscopy revealed div
ersity in composition and structure in the obtained EPS: from glucose mainl
y an alpha -linked mannan, and from dextrins mainly an alpha- and beta -lin
ked glucan.