lipase

yarrowia lipolytica

catalytic efficiency

corynebacterium glutamicum

directed evolution

gene clusters

natural products

organic solvents

metabolic engineering

immobilized lipase

Food chemistry

• Enzymes are screened for catalyzing ester synthesis from Monascus purpureus YJX-8. • Enzyme LIP05 catalyzes short-chain fatty acid ester synthesis in aqueous phase. • Deleting the lid domain enhances enzyme activity of LIP05 by 52.5% • Ultrasound greatly promotes ester synthesis of LIP05 in aqueous phase. Short-chain fatty acid esters are important flavor chemicals in Chinese traditional fermented Baijiu. Monascus purpureus was recognized as an important microorganism contributing to ester synthesis. However, the molecular basis for ester synthesis was still lacking. The present work combined genome sequencing, transcriptome sequencing, gene library construction, and enzyme engineering to discover a novel catalyst from M. purpureus (isolated from Baijiu fermentation starter). Enzyme LIP05, belonging to the α/β hydrolase family, was identified to synthesize short-chain fatty acid esters under aqueous phase. After deleting the lid domain of LIP05, the synthesis of ethyl pentanoate, ethyl hexanoate, ethyl octanoate, or ethyl decanoate was achieved. Ethyl octanoate with the highest conversion ratio of 93.7% was obtained with the assistance of ultrasound. The study reveals the molecular basis for synthesizing short-chain fatty acid esters by M. purpureus and will promote the application of the species or the enzyme in food industry.

Discovery and development of a novel short-chain fatty acid ester synthetic biocatalyst under aqueous phase from Monascus purpureus isolated from Baijiu