Optimization of fermentation conditions for the production of pullulan by a new strain of Aureobasidium pullulans isolated from sea mud and its characterization

A yeast-like fungal strain was isolated from sea mud samples from the beach of the yellow sea near Lianyungang, Jiangsu, China. The characteristics of this strain, i.e., colony, morphology, DNA molecular, and product indicated that it is related to Aureobasidium pullulans family and named A. pullulans CJ001. The fermentation conditions were optimized: fermentation time 4 d, initial pH 6.0, and temperature 22 °C. Under these optimized conditions, this strain produced 31.25 g/L of melanin-free exopolysaccharide (EPS). Fourier-transform infrared (FTIR) spectroscopy of this EPS is almost identical to that of standard pullulan, and High Performance Liquid Chromatography (HPLC) of the hydrolysates of the EPS with pullulanase, which is capable of cutting off α-(1 → 6) linkages, showed that the main composition is maltotriose, and thus confirming the pullulan structure of this EPS.