Effect of carbon source on polysaccharide production by alginate-entrapped Aureobasidium pullulans ATCC 42023 cells

The production of the exopolysaccharide pullulan using entrapped cells of the fungus Aureobasidium pullulans ATCC 42023 was investigated relative to carbon source. Fungal cells grown on glucose or sucrose as a carbon source were entrapped in calcium alginate beads and found to be capable of synthesizing the polysaccharide for two production cycles. Using 2.5% glucose or sucrose as a carbon source, productivity was 18.3 or 21.9 mg polysaccharide/g cells × h, respectively after the initial production cycle and decreased to 9.6 or 8.5 mg polysaccharide/g cells × h, respectively, after the second production cycle. Independent of carbon source, the entrapped fungal cells exhibited a higher yield during the initial cycle than the second production cycle while the entrapped ATCC 42023 cells elaborated a polysaccharide with a higher pullulan content during the second production cycle compared to the initial production cycle.