Enzymatic hydrolysis of carbohydrate-rich Chlorella vulgaris for third-generation bioethanol production by cellulase-recombinant yeast

Abstract

This study developed a multienzyme preparation for the hydrolysis of microalgal biomass. Possible synergism between enzymes was investigated using carbohydrate-rich Chlorella vulgaris biomass. Under optimum experimental conditions, α-amylase (Termamyl®) at 0.05 g−1 substrate and amyloglucosidase at 0.2 g−1 substrate achieved a maximum reducing sugars yield of 5.639 ± 0.32 g L−1 at a biomass loading of 10 g L−1. Saccharomyces cerevisiae JAYET cells modified with cellulase genes produced 8.015 g L−1 ethanol from unenriched whole microalgal hydrolysate. With the developed enzyme preparation, no pretreatment was necessary to convert the carbohydrate-rich fraction of microalgal biomass into third-generation bioethanol.