Enzymatic hydrolysis of raw cassava starch and bioethanol production by Saccharomyces cerevisiae CENPK2 expressing a glucoamylase from Aspergillus awamori

Abstract

This study aimed to verify the hydrolysis of starch raw cassava using a glucoamylase from Aspergillus awamori expressed in Saccharomyces cerevisiae. The glucoamylase activity test plate showed that S. cerevisiae recombinant is able to degrade cassava starch without the needs for either acid pretreatment or cooking. The recombinant yeast was able to form 2.7 g / L of biomass and degrades cassava starch up to 90%, releasing a large amount of glucose to the culture medium. The N-deglycosylation assay showed that the recombinant glucoamylase (75 kDa) has 10% carbohydrate in their structure compared with enzyme treated (65 kDa). Our preliminary results showed that recombinant yeast was able to produce 4.22 g/L in 96 hours fermentation. The results of starch hydrolysis shown that S. cerevisiae recombinant has a great potential for producing ethanol from cassava starch without the need for pretreatment of the substrate.