Fed batch enzymatic saccharification of newspaper cellulosics improves the sugar content in the hydrolysates and eventually the ethanol fermentation by Saccharomyces cerevisiae

The newspaper is comprised of (w w−1) holocellulose (70.0%) with substantial amount of lignin (16.0%). Bioconversion of the carbohydrate component of newspaper to sugars by enzymatic saccharification, and its fermentation to ethanol was investigated. Of various enzymatic treatments using cellulase, xylanase and laccase, cellulase enzyme system was found to deink the newspaper most efficiently. The saccharification of deinked paper pulp using enzyme cocktail containing exoglucanase (20 U g−1), β-glucosidase (60 U g−1) and xylanase (80 U g−1) resulted in 59.8% saccharification. Among additives, 1% (v v−1) Tween 80 and 10 mol m−3 CoCl2 improved the enzymatic hydrolysis of newspaper maximally, releasing 14.64 g L−1 sugars. The fed batch enzymatic saccharification of the newspaper increased the sugar concentration in hydrolysate from 14.64 g L−1 to 38.21 g L−1. Moreover, the batch and fed batch enzymatic hydrolysates when fermented with Saccharomyces cerevisiae produced 5.64 g L−1 and 14.77 g L−1 ethanol, respectively.