Bioprocessing of sweet sorghum within situ-produced enzymes

Abstract

Enzyme-assisted ensiling (ENLAC), usingin situ-produced enzymes fromGliocladium sp. TUB-F-498, preserved 80% of the sugar content of sweet sorghum, and facilitated its extraction by countercurrent diffusion. Thein situ enzyme was produced on the extracted sweet sorghum pulp by an 8-d solid substrate fermentation (SSF) with a yield of 4.6 cellulase and 400 IU/g dry wt xylanase. Two percent of the fermented substrate had cellulase and xylanase levels equivalent or superior to levels found in the commercial enzymes Celluclast and Viscozyme Novo at the 0.025% application level in ENLAC.

Thein situ-production of enzymes on recyclable substrates may reduce bioprocessing costs significantly. In this ENLAC process, the cost of thein situ enzymes is estimated to be about $0.12/MT substrate, compared to $9.5/metric ton (MT) for the commercial enzymes, a cost reduction of nearly 80-fold.