Cold-adapted esterases and lipases: a biodiversity still under-exploited.

Micro-organisms that thrive at low temperatures produce cold-adapted enzymes which generally display high catalytic efficiency making these biocatalysts particularly interesting either for investigating stability/flexibility relationships, or for their quite wide applications. Psychrophilic lipases and esterases have attracted attention because of their increasing use in the organic synthesis of chiral intermediates due to their low optimum temperature and high activity in cold conditions, which are favourable properties for the production of relatively frail compounds. In addition, these enzymes have an advantage under low water conditions due to their inherent greater flexibility, wherein the activity of mesophilic and thermophilic enzymes is severely impaired by an excess of rigidity. In this review we present an up to date overview on some psychrophilic esterases and lipases from microbial sources. The different experimental strategies available for the search of psychrophilic biocatalysts and their application to discover novel cold-adapted lipolytic enzymes will be outlined. Some structural features that justify the unusually high enzymatic activity at low temperature will be discussed, in view of the recent achievements concerning the use of cold-adapted lipases and esterases in the synthesis of fine chemicals.