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A total of 61 yeast strains were obtained from 132 samples collected from various sources such as soil, mushroom, flowers, fruits, tree barks and insect frass in the mixed deciduous forest areas of Phujong Nayoy National Park, Thailand. Based on D1/D2 region at the 5' end of the large subunit ribosomal RNA gene (rRNA gene region D1/D2) analysis, 39 strains were identified as ascomycetous yeasts and distributed to 7 genera i.e. Blastobotrys, Candida, Debaryomyces, Dipodascus, Kodamaea, Pichia and Torulaspora. Twenty strains were identified as basidiomycetous yeasts which belonged to the genera Asterotremella, Cryptococcus, Sporidiobolus and Trichosporon. Another two strains of yeast-like fungi were belonged to genus Aureobasidium. The predominant genus was Candida with a 31.14% contribution. For testing of xylanase and carboxymethyl cellulase production of the 61 strains of yeasts and yeast-like fungi, Candida glabrata and Aureobasidium pullulans showed xylanase activity of 0.91 and 0.52 UmL-1, respectively, and carboxymethyl cellulase activity of 0.38 and 0.44 UmL-1, respectively. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]