Integrated cellulase continuous production and downstream processing using a packed-bed bioreactor for solid-state...

Area of Science:

• Biotechnology and Bioengineering
• Enzyme Technology
• Renewable Energy

Background:

• Solid-state fermentation (SSF) is crucial for efficient, sustainable second-generation bioethanol production via in situ cellulase generation.
• Large-scale SSF implementation for enzyme production faces challenges in heat transfer, bioreactor operation, and downstream processing.

Purpose of the Study:

• To systematically evaluate integrated production, extraction, recovery, and stabilization of endoglucanase using Myceliophthora thermophila I-1D3b.
• To assess batch versus continuous modes in a multilayer packed-bed bioreactor for cellulase production and downstream processing.

Main Methods:

• Cultivation of Myceliophthora thermophila I-1D3b on sugarcane bagasse and wheat bran in a packed-bed bioreactor.
• Fermentation at 45°C for 96h, followed by characterization of enzymatic extracts (pH, temperature).
• Enzyme concentration via ammonium sulfate precipitation and ethanol precipitation; assessment of percolation water flow rate.

Main Results:

• Maximum endoglucanase activity observed at 60°C and pH 4.0, indicating a thermoacidophilic profile.
• Ammonium sulfate precipitation yielded 78.7% recovery and 156 U·g.d.s⁻¹ activity, outperforming ethanol precipitation.
• Batch and continuous operations showed similar average activities (approx. 96 U·g.d.s⁻¹), with continuous mode offering improved spatial homogeneity and reduced variability.

Conclusions:

• Integrated process design, including thermal control and percolation-based extraction, enhances SSF robustness for cellulase production.
• Ammonium sulfate precipitation is superior for recovering endoglucanase activity from SSF extracts.
• The developed process is suitable for industrial applications, improving the efficiency and sustainability of bioethanol production.