Simultaneous production of cellulase and xylanase by Penicillium occitanis Pol6 and potential application in bioethanol production using cardboard waste as a sustainable substrate
摘要
In Tunisia, paper and cardboard waste pose a significant environmental and energy burden. To address this, authorities are encouraging innovative biotechnological methods to transform these cellulose-rich wastes into valuable products like low-cost enzyme-inducing substrates. In this context, many industrialists are interested in co-producing multienzymes from a single potential microbe. Penicillium occitanis Pol6 was investigated for its potential to coproduce cellulase and xylanase in a cardboard waste-based medium. The simultaneous production of these two enzymes was optimized using response surface methodology (RSM) with a central composite design approach. The highest generation of cellulase (2.44 ± 0.07 U/mL) and xylanase (22.90 ± 3.84 U/mL) was reached with an initial cardboard waste (CW) concentration of 3 g/L and an inoculum size of 2%. The validation experiment confirmed the adequacy and accuracy of the proposed models. The enzymatic complex was used to hydrolyze CW, releasing 55 g L−1 of reducing sugars after 24 h of saccharification of 120 g/L substrate. Fermentation of 4% of cardboard waste hydrolysates (CWH) with S. cerevisiae yielded a maximum bioethanol production of 15.5 g/L after 24 h of alcoholic fermentation. These results highlight the cost-effective potential of using CW as an inductive feedstock for simultaneous production of cellulase and xylanase by P. occitanis Pol6, offering significant benefits for both the economy and the environment.