Enhanced cellulase production by decreasing intercellular pH through H⁺-ATPase gene deletion in Trichoderma reesei...

Area of Science:

• Biotechnology
• Molecular Biology
• Enzyme Engineering

Background:

• Trichoderma reesei is a key microorganism for industrial lignocellulose degradation.
• Cellulolytic enzymes from T. reesei are vital for biofuel and chemical production.
• Intracellular pH is hypothesized to influence cellulase induction during fermentation.

Purpose of the Study:

• To investigate the role of intracellular pH in cellulase induction in T. reesei.
• To identify and characterize genes involved in intracellular pH maintenance.
• To explore novel strategies for enhancing cellulase production.

Main Methods:

• Identification and gene deletion of H+-ATPase genes (tre76238 and tre78757) in T. reesei.
• Fermentation studies using glucose as a sole carbon source.
• Measurement of intracellular pH, cytosolic Ca2+ levels, and cellulase activity.

Main Results:

• The tre76238 gene plays a major role in maintaining intracellular pH in T. reesei.
• Deletion of tre76238 led to high cellulase production on glucose, accompanied by intracellular acid accumulation and growth retardation.
• Intracellular acid accumulation triggered increased cytosolic Ca2+ levels, which were necessary for cellulase production.

Conclusions:

• A novel mechanism for cellulase regulation in T. reesei under low intracellular pH conditions was identified.
• The tre76238 deletion strain exhibits altered cellulase expression patterns.
• Optimizing nitrogen sources can mitigate growth retardation and facilitate scale-up of cellulase production.