Production of isobutyric acid from methanol by Clostridium luticellarii†
Renewable methanol can be used as a feedstock to generate value-added multicarbon components through fermentation technologies. Recently, researchers reported the production of isobutyric acid using methanol as an electron donor with open culture systems dominated by Eubacterium sp. and Clostridium sp. Here we report the ability of Clostridium luticellarii wild-type strain to produce isobutyric acid from methanol and CO2 & H2. When growing on methanol, the supplementation of acetic and butyric acid enhanced isobutyric acid final concentration, selectivity and production rate. A maximum of 5.04 ± 0.08 g L−1 isobutyric acid was produced at a rate of 0.420 ± 0.012 g L−1 d−1and selectivity of 0.70 electron per electron of total products in batch with acetic and butyric acid as electron acceptors. The pH was also found to be a major factor influencing isobutyric acid formation with maximal production at pH 6.50. Finally, in addition to its ability to produce isomers, C. luticellarii was able to perform C2-unit elongation from methanol. Overall, this study positions C. luticellarii as a promising platform for the production of isocarboxylic acids.