title: Pullulan production by tropical isolates of Aureobasidium pullulans.
abstract: Tropical isolates of Aureobasidium pullulans previously isolated from distinct habitats in Thailand were characterized for their capacities to produce the valuable polysaccharide, pullulan. A. pullulans strain NRM2, the so-called "color variant" strain, was the best producer, yielding 25.1 g pullulan l(-1) after 7 days in sucrose medium with peptone as the nitrogen source. Pullulan from strain NRM2 was less pigmented than those from the other strains and was remarkably pure after a simple ethanol precipitation. The molecular weight of pullulan from all cultures dramatically decreased after 3 days growth, as analyzed by high performance size exclusion chromatography. Alpha-amylase with apparent activity against pullulan was expressed constitutively in sucrose-grown cultures and induced in starch-grown cultures. When the alpha-amylase inhibitor acarbose was added to the culture medium, pullulan of slightly higher molecular weight was obtained from late cultures, supporting the notion that alpha-amylase plays a role in the reduction of the molecular weight of pullulan during the production phase.
authors.affiliation: Plant Biomass Utilization Research Unit, Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Sehanat
authors.initials: S
authors.lastname: Prasongsuk
authors.forename: Mark A
authors.initials: MA
authors.lastname: Berhow
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Dunlap
authors.forename: David
authors.initials: D
authors.lastname: Weisleder
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Leathers
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Eveleigh
authors.forename: Hunsa
authors.initials: H
authors.lastname: Punnapayak
mesh_terms: D020909:Acarbose / Q000494:pharmacology*; D001203:Ascomycota / Q000201:enzymology / Q000254:growth & development* / Q000302:isolation & purification; D018929:Cell Culture Techniques; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005936:Glucans / Q000032:analysis / Q000096:biosynthesis* / Q000737:chemistry; D008970:Molecular Weight; D011134:Polysaccharides / Q000032:analysis / Q000096:biosynthesis / Q000737:chemistry; D013785:Thailand; D000516:alpha-Amylases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D005936:Glucans; D011134:Polysaccharides; C009109:pullulan; D000516:alpha-Amylases; D020909:Acarbose