Comparative Metabolomic Study of Anaerobic and Aerobic Processings of Metabolite Sample Preparation for Clostridium Acetobutylicum

Clostridium acetobutylicum, a Gram-positive strict anaerobe, has been actively used for producing butanol that is considered as an important chemical feedstock and biofuel. Recently, metabolic engineering is vigorously exploited to improve the fermentation performance of C. acetobutylicum for the production of butanol. Metabolomics is also used to elucidate the metabolic snapshot and signature of metabolically engineered strains, and these information can be used for further improvement of engineered strains. To obtain reliable metabolomic data, the reproducible, nonselective, reliable and efficient metabolome sample preparation is essential. Currently, the metabolite sample preparation method, which was originally developed for Escherichia coli, has been used for C. acetobutylicum without any evaluation under anaerobic conditions. The necessity of customization of metabolite sample preparation depending on the specificity of microorganisms is already revealed by several other studies. In this study, we systematically compared atmospheric and anaerobic processings and evaluated extraction solvents for metabolome sample preparation methods for C. acetobutylicum by focusing on the metabolomic discrimination of acidogenic and solventogenic phases. The metabolite analysis was performed by gas chromatography/time-of-flight mass spectrometry. The results of this study could be used as a standard procedure for the metabolite sample preparation of the metabolomics and metabolic engineering of C. acetobutylicum.