Research Article
Oscar Tirado-Acevedo, Jacqu
Abstract
Syngas fermentation is considered an alternate processing method for biofuel and biochemical production as part of thermochemical biomass conversion. Exposure of syngas fermenting microorganisms to sugars, either in the primary syngas fermentation or through pre-adaptation in the seed culture, has the potential to enhance overall fermentation performance and stress tolerance. In this rapid communication, Clostridium ljungdahlii was grown on different carbon sources including syngas only, syngas-fructose and fructose only to identify ideal pre-adaptation conditions for ethanol and acetate production from subsequent cultures grown in reactors containing syngas only or fructose-syngas substrates. In syngas only reactors, cultures pre-adapted to fructose had faster cell production rates (2X) and at least 83% higher ethanol and 16% higher acetate formation than cells pre-adapted on syngas or syngas-fructose. In syngas- fructose reactors, cultures did not show significant growth or acetate production differences under pre-adaptation treatments. Nevertheless, in these syngas-fructose reactors, cultures pre-adapted on syngas and syngas-fructose had nearly 20% higher ethanol production than those pre-adapted on fructose. Among pre-adaptation treatments, fructose had better results in syngas only reactors than syngas-fructose reactors. However, the presence of syngas in pre- adaptation cultures was better overall for ethanol production.