Biosynthesis of Diverse Antimicrobial and Antiproliferative Acyloins in Anaerobic Bacteria

Metabolic profiling and genome mining revealed that anaerobic bacteria have the potential to produce acyloin natural products. In addition to sattazolin A and B, three new sattazolin congeners and a novel acyloin named clostrocyloin were isolated from three strains of Clostridium beijerinckii, a bacterium used for industrial solvent production. Bioactivity profiling showed that the sattazolin derivatives possess antimicrobial activities against mycobacteria and pseudomonads with only low cytotoxicity. Clostrocyloin was found to be mainly active against fungi. The thiamine diphosphate (ThDP)-dependent sattazolin-producing synthase was identified in silico and characterized both in vivo and in in vitro enzyme assays. A related acyloin synthase from the clostrocyloin producer was shown to be responsible for the production of the acyloin core of clostrocyloin. The biotransformation experiments provided first insights into the substrate scope of the clostrocyloin synthase and revealed biosynthetic intermediates.