CO-dependent H2 production by genetically engineered Thermococcus onnurineus NA1

Area of Science:

• Microbiology
• Biotechnology
• Renewable Energy

Background:

• Hydrogen gas (H2) production via hydrogenic CO oxidation (CO + H2O → CO2 + H2) is a promising avenue for clean, renewable fuel generation.
• The microorganism Thermococcus onnurineus NA1 naturally utilizes CO for growth and H2 production, possessing a unique gene cluster for carbon monoxide dehydrogenase (CODH) and hydrogenase.

Purpose of the Study:

• To enhance hydrogen (H2) production by genetically engineering Thermococcus onnurineus NA1.
• To investigate the role of a specific gene cluster in carboxydotrophic hydrogenic metabolism.

Main Methods:

• Gene disruption and transcriptional analysis were employed to identify essential genes for CO metabolism.
• A strong promoter was used to control the expression of the identified gene cluster in a mutant strain (MC01).
• Bioreactor cultures were used to assess H2 production rates and yields of the engineered strain.

Main Results:

• The engineered MC01 mutant exhibited a 30-fold increase in mRNA transcription for CODH, hydrogenase, and Na+/H+ antiporter.
• MC01 demonstrated a 1.8-fold higher specific activity for CO-dependent H2 production compared to the wild-type.
• The H2 production potential in bioreactors was 3.8-fold higher in the MC01 mutant, with rates exceeding previously studied CO-dependent H2-producing prokaryotes.

Conclusions:

• Genetic engineering of the CODH-hydrogenase gene cluster significantly enhances H2 production in Thermococcus onnurineus NA1.
• The engineered strain shows high efficiency in converting industrial waste gases, such as those from steel production, into H2.
• This study pioneers the use of carboxydotrophic hydrogenic microbes for H2 production from steel mill waste gas.