Robust production of pigment-free pullulan from lignocellulosic hydrolysate by a new fungus co-utilizing glucose and xylose.

Cost-efficient production of pullulan is of great importance but remains challenging due largely to the high-cost carbon sources. Lignocellulosic biomass is considered an alternative carbon source for industrial pullulan production, while new fungus producers that co-utilizing lignocellulose-derived glucose and xylose are required. In this study, a new fungus Aureobasidium melanogenum TN2-1-2 showed simultaneously assimilation of glucose and xylose and could produce pigment-free pullulan due to its deficiency in melanin synthesis. The ability of TN2-1-2 producing pullulan was remarkably robust in the presence of varying glucose to xylose ratios and ionic salt concentrations. Furthermore, condensed lignocellulosic hydrolysates obtained by consolidated biosaccharification was used as the pullulan production medium without supplying any nutrients, and pigment-free pullulan was produced by TN2-1-2 with the titer and yield of 55.1 g/L and 0.5 g/g, respectively. Hence, this work provides a potential industrial pullulan producer TN2-1-2 and new insight into the lignocellulose bioconversion to pullulan.