Enhancing acetic acid and 5?hydroxymethyl furfural tolerance of C. saccharoperbutylacetonicum through adaptive laboratory evolution

In this study, adaptive laboratory evolution (ALE) was applied to isolate four strains of Clostridium saccharoperbutylacetonicum able grow in the presence hemicellulosic hydrolysate inhibitors unsupported by parental strain. Among them, RAC-25 presented best fermentative performance, producing 22.1 g/L ABE and 16.7 butanol. Genome sequencing revealed a deletion arabinose transcriptional repressor gene (araR) mutation anti-sigma factor I that promoted downregulation sigI. Gene expression analysis indicated high genes related H+-pumps (ATP synthases), proline biosynthesis (gamma phosphate reductase) chaperonins (Grol), suggesting an integrated mechanism is probably coordinated repression Therefore, addition highlighting power ALE for selecting robust strains, our results suggest sigI araR may be interesting targets increased tolerance toward inhibitor compounds relevant lignocellulosic biofuels production.