7-82: Enzymatic synthesis of the cellulases inducer gentiobiose by β-glucosidase of Aspergillus awamori and of Prunus dulcis

The hydrolysis of cellulose is catalyzed by cellulases, i.e., endoglucanases and exoglucanases. These enzymes are majorly produced by fungi and are induced by disaccharides such as gentiobiose, cellobiose, and sophorose.  This work studied the production of these disaccharides via the condensation reaction of D-glucose 90% (w/v) mediated by β-glucosidase (8.4 IU/mL) from Aspergillus awamori or Prunus dulcis. Reactions were incubated for 96 hours and the formation of dissacharides was analyzed by HPLC. In the reaction medium presenting P. dulcis β-glucosidase the glucose conversion reached 34% (288 g/L) and in media containing the enzyme from A. awamori conversion reached 22% (178 g/L). Gentiobiose was the predominant product formed in both cases. The evaluation of the effect of temperature (45 ºC to 65 ºC) and of pH (3.5 to 4.5) allowed the identification of the best reaction conditions. As such in a reaction carried out for 24h at 55ºC and pH 4 the use of β-glucosidase of  P. dulcis allowed the formation of 125 g/L gentiobiose while in a reaction carried out for 48h at 65 ºC and pH 4 the enzyme of A. awamori allowed the formation of 76 g/L gentiobiose. Considering the aforementioned results, β-glucosidase from Prunus dulcis showed to be the most promising biocatalyst for the synthesis of gentiobiose.