Hydrolysis of Orange Peel with Cellulase and Pectinase to Produce Bacterial Cellulose using Gluconacetobacter xylinus

Oranges (Citrus sinensis) are the world's most processed fruit. The waste from processing is rich in soluble sugars, cellulose, hemicelluloses and pectin and therefore has potential as feedstock for bacterial cellulose (BC) production. In this study, cellulase and pectinase were used to hydrolyze orange peel in order to increase the amount of fermentable sugars. Response surface methodology was used to evaluate the effects of reaction parameters, and 80.99 g/L reducing sugar was obtained with cellulase of 1589.41 U/g, pectinase of 31.75 U/g and a reaction time of 5.28 h. Besides, the orange peel fluid and orange peel hydrolysate were used as the culture media for Gluconace-tobacter xylinus during BC production. The orange peel media have no significant inhibiting effect on the fermentation activity of G. xylinus for BC production. As an acetic acid buffer was used or nitrogen source was added to the orange peel media, BC production was 4.2-6.32 times higher than that in traditional Hestrin and Schramm (HS) medium. The SEM and IR spectra showed that the BC produced was not much different than that produced in HS medium. These results demonstrate that orange peel not only can be used as a low cost feedstock to produce BC, but it also provides a solution to the waste disposal problem of the orange juice industry.