|Prasongsuk, S. - CHULALONGKORN UNIV-THAILA|
|Eveleigh, D. - RUTGERS UNIV-NJ|
|Punnapayak, H. - CHULALONGKORN UNIV-THAILA|
Submitted to: Society of Industrial Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 25, 2005
Publication Date: August 25, 2005
Citation: Prasongsuk, S., Leathers, T.D., Eveleigh, D.E., Punnapayak, H. 2005. Pullulan production by tropical isolates of aureobasidium pullulans [abstract]. Society of Industrial Microbiology. p. 94. Technical Abstract: Tropical isolates of A. pullulans were obtained from distinct habitats in Thailand, from leaf to indoor surfaces. These isolates appeared to be so-called "color variant" strains, with pink, red, or yellow pigmentation. In order to obtain the highest pullulan - producing strain, isolates were optimized for pullulan production in liquid culture media containing various carbon and nitrogen sources. A. pullulans strain NRM2 (pink colony) was the best pullulan producer, yielding 25 g/l after 7 days in sucrose medium with peptone as a nitrogen source. Pullulan from this strain also contained less melanin than pullulan from other strains tested. During cultivation for pullulan production, blastospores were the only cellular morphotype observed. The molecular weight of pullulan dramatically decreased in cultures after 3 days growth, as analyzed by high performance size exclusion chromatography. Alpha-amylase and pullulanase were induced by starch and also constitutively when grown on sucrose. Culture on sucrose also led to the reduction in the molecular weight of the initially formed pullulan. When the alpha-amylase inhibitor acarbose was added to the culture medium, pullulan with a higher molecular weight product was obtained from late cultures. This supports the idea that alpha-amylase plays a role in the reduction of the molecular weight of pullulan during the production phase.