Whole-crop biorefinery of corn biomass for pullulan production by Aureobasidium pullulans

[Display omitted] •Whole-crop biorefinery of corn biomass was used for efficient pullulan production.•A. pullulans CCTCC M 2012259 is sensitive to whole corn biomass hydrolysate.•A. pullulans EV6 with strong adaptability to hydrolysate was screened by ALE.•The reason of increases in titer and Mw of pullulan produced by EV6 was revealed. In the present study, corn starch, cob, and straw were biorefined and used as feedstocks for the production of pullulan. The titer and molecular weight (Mw) of pullulan significantly decreased when corn cob and straw hydrolysates were utilized by the parental strain Aureobasidium pullulans CCTCC M 2012259 (PS). Based on adaptive laboratory evolution of PS, an evolved strain A. pullulans EV6 with strong adaptability to the whole corn biomass hydrolysate and high capability of pullulan biosynthesis was screened. Batch pullulan fermentation results indicated that EV6 produced an increased titer of pullulan with a higher Mw than PS. The underlying reasons for these increases were revealed by assaying key enzymes activities and measuring intracellular uridine diphosphate glucose levels. Subsequently, whole-crop biorefinery of corn biomass was conducted, and the results confirmed that whole corn crop has immense potential for efficient pullulan production.