Halophilic Archaeal Lipases and Esterases: Activity, Stability, and Food Applications

Abstract

Lipases and esterases are able to hydrolyze triglycerides, and they are important biocatalysts in food industry. There are many sources of these enzymes. One of the most interesting and unexplored sources of microbial lipases/esterases is the Archaea domain. Most of the archaea produces “extremozymes” that are able to act at harsh conditions such as high temperature, acidic or alkaline pH, high pressure, etc. Particularly, halophilic archaea is a group of microorganisms able to produce lipases and esterases active at a high salt concentration. Nowadays, only a few lipases/esterases from halophilic archaea have been described; however, the reports indicate that halophilic archaeal lipases/esterases are stable at neutral pH, high salt concentration, high temperature, and in hydrophilic solvents. This chapter describes the special features of halophilic archaeal lipases and esterases characterized until now and optimal conditions for their activity and solvent stability. Their substrate preferences were analyzed. Halophilic archaeal lipase/esterase sequences reported in different databases were analyzed. With this analysis we found the evidence of the typical characteristics of lipases/esterases from halophilic archaea: acidic isoelectric point, low molecular weight, and a high content of aspartic and glutamic amino acids. The few halophilic lipases and esterases characterized until now show a preference to hydrolyze vinyl esters and mono- and diglycerides with low activity in triglycerides. Studies on the application of halophilic lipases and esterases in food industry are scarce. However, they have great potential in some processes, like in synthesis of high-value products like structured lipids useful as food additives. The use of lipolytic archaeal enzymes in seafood ripening is an emerging trend. An extensive research is needed in order to develop food applications.