ljungdahlii

Clostridium ljungdahlii is a Gram-positive, anaerobic, rod-shaped bacterium in the genus Clostridium. It is an acetogenic organism that fixes carbon via the Wood-Ljungdahl pathway. It is typically found in anaerobic environments, including soils, sediments, and industrial gas streams, where reducing conditions prevail. The species name honors Lars Ljungdahl for work on acetogenic metabolism.

Metabolism and energetics: C. ljungdahlii can utilize carbon monoxide, carbon dioxide with hydrogen, or syngas as carbon and energy sources. The main products are acetate and ethanol, with the relative proportions influenced by gas composition, pH, and culture conditions. Growth occurs under strict anaerobiosis, and carbon fixation proceeds via the CODH/ACS enzyme complex as part of the Wood-Ljungdahl pathway.

Genomics and physiology: The genome has been sequenced and reveals genes encoding the CODH/ACS complex, hydrogenases, and other components of the Wood-Ljungdahl pathway, along with enzymes supporting energy conservation and redox balancing. It is generally regarded as non-pathogenic and is studied primarily for biotechnological applications.

Applications and significance: C. ljungdahlii is explored for industrial gas fermentation to produce acetate, ethanol, and other chemicals from syngas, enabling conversion of CO- and CO2-rich wastes into value-added products. Research focuses on reactor design, product yields, and integration with carbon utilization and, potentially, carbon capture strategies.