UC Berkeley

The production of ABE (acetone, butanol, ethanol) by members of the anaerobic bacterial genus Clostridium is a bioprocess capable of converting various renewable substrates into high-value solvents and fuels. While ABE fermentation by clostridia has been performed on an industrial scale since the early 20th Century, several significant technical challenges have prevented this process from being economically competitive with the conventional production of solvents and fuels from petroleum. Here, we discuss the role which signaling small molecules (SSMs) play in controlling industrial traits of solvent-producing species of Clostridium. This includes our discovery and characterization of a family of polyketides from the model ABE-producer Clostridium acetobutylicum ATCC 824, which we demonstrate are important in influencing solvent production and controlling morphological differentiation in this organism. Additionally, we describe the development of genetic tools and techniques for genome editing of another industrial solvent-producing species, Clostridium saccharoperbutylacetonicum strain N1-4 (C. s. N1-4). Applying these methods, we present preliminary results which suggest that SSMs may play critical roles in controlling ABE production in C. s. N1-4. Finally, we present our discovery of the first known non-ribosomal peptide isolated from an anaerobic organism. Through this work, we hope to highlight the significant role of secondary metabolites in clostridial fermentations (as well as anaerobes in general), and provide a relatively unexplored strategy for improving this promising renewable bioprocess.