Assessment of the ability of Meyerozyma guilliermondii P14 to produce second-generation bioethanol from giant reed (Arundo donax) biomass

The present study was aimed to evaluate the ability of Meyerozyma guilliermondii P14 to produce bioethanol from pretreated biomass of giant reed (Arundo donax). The wild yeast was isolated from its natural habitat and identified by phylogenetic analysis. Arundo donax biomass was sequentially pretreated by acid and alkali treatments to break the recalcitrant structure. The pretreated biomass was analysed by FTIR spectroscopy and scanning electron microscopy to observe the structural changes in the biomass. Pretreated biomass was then enzymatically saccharified, and the resultant broth was used to produce ethanol by M. guilliermondii P14. The fermentation parameters such as pH, temperature, composition of media, and agitation rate were optimized prior to saccharified broth-based fermentations. The results of this study revealed that the dual pretreatment of biomass could make 90.56% cellulose accessible for enzymatic attack. Subsequently, saccharification of pretreated biomass with two enzyme variants resulted in conversion efficiency of 85–87%. Fermentation of saccharified broth resulted in 32.89 g/L final ethanol concentration at 72 h. This has corresponded to 0.48 g/g of ethanol yield and 0.456 g/L/h volumetric productivity. M. guilliermondii is known to utilize both pentose and hexose sugars unlike Saccharomyces cerevisiae which makes it a major player in cellulosic ethanol production. This study provides a significant evidence to the information pool of second-generation bioethanol production from unconventional glucose fermenting yeasts.