Light calcium carbonate improves pullulan biosynthesis by Aureobasidium pullulans under high concentration of sugar.

The effects of light calcium carbonate (CaCO) on pullulan biosynthesis by Aureobasidium pullulans NCPS2016 were investigated. Light CaCO enhanced pullulan production by 12.4 % when added to the low concentration of fructose broth compared with KHPO. Pullulan production was further improved when increasing both the concentrations of light CaCO and fructose. Compared to KHPO, light CaCO improved the activities of UDP-glucose pyrophosphorylase, α-phosphoglucose mutase, UDP-glucosyltransferase, and glucosyltransferase relevant to pullulan biosynthesis, and the gene transcriptional levels of UDP-glucose pyrophosphorylase, α-phosphoglucose mutase, UDP-glucosyltransferase, and glucose kinase were enhanced. During 30-liter fermentation, 144.3 g/L of purified pullulan was produced from 200 g/L of fructose and 15 g/L of light CaCO within 168 h, with the yield and productivity of 0.72 g/g and 0.86 g/L/h respectively. This is the first report that light CaCO improves pullulan production significantly.