Functional Characterization of a Robust Marine Microbial Esterase and Its Utilization in the Stereo-Selective Preparation of Ethyl (S)-3-Hydroxybutyrate

One novel microbial esterase PHE21 was cloned from the genome of Pseudomonas oryzihabitans HUP022 identified from the deep sea of the Western Pacific. PHE21 was heterologously expressed and functionally characterized to be a robust esterase which behaved high resistance to various metal ions, organic solvents, surfactants, and NaCl. Despite the fact that the two enantiomers of ethyl 3-hydroxybutyrate were hard to be enzymatically resolved before, we successfully resolved racemic ethyl 3-hydroxybutyrate through direct hydrolysis reactions and generated chiral ethyl ( S )-3-hydroxybutyrate using esterase PHE21. After process optimization, the enantiomeric excess, the conversion rate, and the yield of desired product ethyl ( S )-3-hydroxybutyrate could reach 99, 65, and 87 %, respectively. PHE21 is a novel marine microbial esterase with great potential in asymmetric synthesis as well as in other industries.