A yeast-like fungus producing a large amount of extracellular polysaccharidewas isolated fromthe biogas
reactors at NorthWyke Research, UK (latitude, 50◦
46
29
N; longitude, 3◦
55
23
W). This strain was iden-
tified as Aureobasidiumpullulans based on nucleotide sequence of the D1/D2 domain of the large-subunit
(LSU) rRNA gene. Extracellular polysaccharide or pullulan, produced from this new strain of A. pullulans
in shake flasks and a stirred tank fermenter was investigated. Amaximumpolysaccharide concentration
of 40.1 g l
−1, and productivity of 12.5 g l
−1 per day was obtained in a batch culture from stirred tank fer-
menter. The optimal cultivation conditions for pullulan production for this strain in 250ml shake flask
containing 100ml of sucrose medium were observed at 28 ◦
C and with 200 rpm. The effect of different
sugars and nitrogen sources on pullulan production was investigated. It was found that more pullulan
was produced when the strain was grown in the medium supplemented with NaNO3 than when it was
cultivated in the medium supplemented with C5 and C6 sugars and other nitrogen sources.