Direct biotransformation of nonanoic acid and its esters to azelaic acid by whole cell biocatalyst of Candida tropicalis

Abstract

Azelaic acid is an α,ω-dicarboxylic acid with nine carbons and has multiple applications in plastic and cosmetic industries. Chemical oxidation of oleic acid with ozone (called ozonolysis) allows the production of azelaic acid and a major byproduct of nonanoic acid. To increase the total yield of azelaic acid in the ozonolysis, in this study, sustainable biotransformation process using a whole cell biocatalyst was developed to directly convert nonanoic acid and its esters to azelaic acid. Candida tropicalis ATCC20962 immediately cleaved ethyl nonanoate to nonanoic acid after ethyl nonanoate addition, and then converted nonanoic acid into azelaic acid with the aid of nonane addition and continuous glucose supply. Finally, a fed-batch biotransformation by continuous feeding of pure nonanoic acid resulted in the production of 30.1 g/L azelaic acid with 0.30 g/L-h productivity and 90% molar yield. By combination of the ozonolysis and our process, a maximum of 95% molar carbon yield of azelaic acid from oleic acid was estimated. This is the first report that nonanoic acid and its esters were directly biotransformed to azelaic acid with over 90% yield, and would be a groundwork for the biotransformation of fatty acids with under nine carbons to the corresponding α,ω-dicarboxylic acids.