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

Abstract

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, 11.75g.L^-1 of pullulan with high melanin content (45.70UA_540nm.g^-1) was obtained, this production improved in process assisted by blue LED light, that resulted in 15.77g.L^-1 of pullulan with reduced content of melanin (4.46UA_540nm.g^-1). By using sugarcane bagasse (SCB) hydrolysate as carbon source, similar concentration of pullulan (about 20g.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.

Keywords: Enzymatic hydrolysate; Exopolysaccharide (EPS); Light-emitting diode; Melanin pigment; Pullulan; Sugarcane bagasse.