High-throughput screening of thermostable esterases for industrial bioconversions

Thermostable esterases are used in biocatalysis for the synthesis of a variety of products, for example, flavour esters, emulsifiers, or pharmaceutical intermediates. Industrial enzymatic conversions to obtain chemo-, regio-, and stereoselective transformations may require thermostable enzymes active in organic solvents at high temperatures. To find novel enzymes for industrial bioconversions, we have used a new generation of thermostable reporter substrates (CLIPS-O for Catalyst Identification ProcesS per Oxidization) to screen for esterase activity in thermophilic microorganisms belonging to various thermophilic genus. One of the strains (belonging to Thermus genus) exhibiting activity on short- and long-chain ester CLIPS-O substrates has been selected. The genomic library of this strain was screened using a high-throughput functional technology. Positive clones expressing esterases active at high temperature were immediately characterized during screening for chain-length specificity.