Low-melanin containing pullulan production from sugarcane bagasse hydrolysate by Aureobasidium pullulans in fermentations assisted by light-emitting diode

Pullulan is a polymer produced by Aureobasidium pullulans and the main bottleneck for its industrial production is the presence of melanin pigment. In this study, light-emitting diodes (LEDs) of different wavelengths were used to assist the fermentation process aiming to produce low-melanin containing pullulan by wild strain of A. pullulans LB83 with different carbon sources. Under white light using glucose-based medium, 11.75 g.L⁻¹of pullulan with high melanin content (45.70 UA_540nm.g⁻¹) was obtained, this production improved in process assisted by blue LED light, that resulted in 15.77 g.L⁻¹of pullulan with reduced content of melanin (4.46 UA_540nm.g⁻¹). By using sugarcane bagasse (SCB) hydrolysate as carbon source, similar concentration of pullulan (about 20 g.L⁻¹) was achieved using white and blue LED lights, with lower melanin contents in last. Use of LED light was found as a promising approach to assist biotechnological process for low-melanin containing pullulan production.