Phenolic compounds inhibit cellulase and xylanase activities of Cellulomonas flavigena PR-22 during saccharification of sugarcane bagasse

- Biomass saccharification is one of the most important steps for the production of bioethanol.
- Phenolic compounds (PCs) released during biomass saccharification inhibit holocellulase activities.
- Polyethylene glycol and polyvinylpyrrolidone can prevent PCs inhibition of holocellulases.
- The cellulase and xylanase activities showed different susceptibility toward PCs.

The enzymatic hydrolysis of sugar cane bagasse (SCB) releases simple fermentable sugars however, phenolic compounds (PCs) are also released from the lignin present in the structure of the lignocellulosic biomass limiting the production of sugars and therefore the fermentative process to convert these sugars to bioethanol. During the saccharification of SCB with holocellulases from Cellulomonas flavigena PR-22, 46 μg mL−1 of PCs were produced, which inhibited 87 and 74% carboxymethyl cellulase (CMCase) and xylanases respectively resulting in a low concentration of reducing sugars (5.5 g L−1) at the end of the process. Polymers such as polyethylene glycol 4000 (PEG) and polyvinylpyrrolidone (PVP) can prevent this inhibition due to their ability to chemically adsorb PCs. PEG and PVP were added to C. flavigena PR-22 enzyme extracts at 0.4% (w/v). PEG 4000 prevented CMCase inhibition, maintaining the original activity after the saccharification process, whereas xylanase production was increased by 47% when PVP was added.