Gradual salinity acclimation drives continuous co-production of ectoine and microbial proteins from carbon dioxide

Area of Science:

• Biotechnology
• Microbial Engineering
• Sustainable Chemistry

Background:

• Next-generation biorefineries face challenges in converting carbon dioxide (CO2) into high-value products due to microbial system limitations.
• Ectoine and microbial proteins (MPs) are valuable pharmaceutical and nutraceutical compounds, but their CO2-based bioproduction is hindered by low productivity and growth inhibition.

Purpose of the Study:

• To develop a robust bioproduction strategy for the continuous co-production of ectoine and MPs from CO2 and hydrogen (H2).
• To enhance the stability and productivity of microbial consortia under salinity stress using gradual acclimation.

Main Methods:

• A salinity-selected halophilic microbial consortium, initially a defined co-culture, was subjected to gradual salinity acclimation.
• Salinity was used as a selective pressure to restructure the microbial community and influence carbon allocation.
• The system's performance was monitored for ectoine and MP production and community shifts.

Main Results:

• Maximum ectoine productivity reached 8.3 ± 0.1 mg L−1 d−1 with a specific ectoine content of 22.6 ± 1.4% (w/w) at 8% NaCl.
• High microbial protein (MP) levels (63.3 ± 3.0% w/w) were consistently sustained.
• Gradual salinity increase enabled adaptation, stable operation without inhibitory metabolites, and enrichment of a halotolerant consortium.

Conclusions:

• Gradual salinity acclimation is an effective strategy to enhance microbial robustness and productivity for CO2-based bioproduction.
• This approach supports the development of adaptable bioprocesses capable of sustained ectoine and MP co-production under salinity stress.
• The findings contribute to advancing next-generation biorefineries for sustainable chemical and biomaterial production.