Pullulan production by an osmotolerant Aureobasidium pullulans RBF-4A3 isolated from flowers of Caesulia axillaris

• Published in: Carbohydrate polymers 2011-02, Vol.83 (4), p.1547-1552
• Main Authors: Choudhury, Anirban Roy, Saluja, Puja, Prasad, G.S.
• Format: Article
• Language: English
• Subjects: Applied sciences; Aureobasidium pullulans; Bioconversions. Hemisynthesis; Biological and medical sciences; Biotechnology; chemical structure; Exact sciences and technology; Exopolysaccharide; exopolysaccharides; Fermentation; flowers; Fourier transform infrared spectroscopy; Fundamental and applied biological sciences. Psychology; fungi; glucose; Methods. Procedures. Technologies; Natural polymers; osmotolerance; Osmotolerant; Physicochemistry of polymers; Pullulan; Starch and polysaccharides; wild plants
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2010.10.003

Phenotypic and molecular characterization of five yeast-like fungal isolates from flowers of wild plants showed that they are related to Aureobasidium pullulans. Compared to other isolates, an osmotolerant and non-pigmented isolate A. pullulans RBF-4A3 produced 26.35 g l −1 of melanin-free exopolysaccharide (EPS) in 96 h at 30 °C in 5% glucose containing medium. At higher concentrations of glucose (7.5–25% (w/v)), the EPS produced by this organism increased from 34.68 to 66.79 g l −1 up to 15% (w/v) glucose, with a productivity of 16.69 g l −1 per day. Beyond 15% (w/v) glucose concentration, the EPS production decreased gradually to 43.29 g l −1 at 25% (w/v) glucose. Fourier-transform infrared (FTIR) spectroscopy confirmed that chemical structures of the exopolysaccharide produced by A. pullulans RBF-4A3 and standard pullulan were identical. This is the first report of pullulan production at 15% (w/v) concentration of glucose by an osmotolerant strain of A. pullulans.