Gas Fermentation Expands the Scope of a Process Network for Material Conversion

Biotechnological fermentation is a well-established process, however, it is far from being fully understood and exploited. A new area of fermentation technology that has evolved over the recent decades is gas fermentation. Many microorganisms have been reported in literature to be capable of utilizing a variety of gases such as CO, CO2, H-2, and CH(4)under anaerobic or aerobic conditions as their main carbon and/or energy source. Mostly waste stream gases from industrial plants or those that can be produced via the gasification of solids are investigated. This review focuses on the currently available scientific knowledge about gas fermentation processes, particularly anaerobic syngas fermentation and aerobic methane fermentation. Gas fermentation processes are compared with aerobic and anaerobic fermentation processes based on dissolved solid substrates. Also, the potential of gas fermentation when integrated into a biotechnological network of processes is outlined.