chapter  29
Microbial Lipases
Pages 40

I. Introduction ....................................................................................................................... 767 II. Lipases from Different Sources ........................................................................................ 768

A. Animals ..................................................................................................................... 768 B. Plants ......................................................................................................................... 768 C. Microbes.................................................................................................................... 769

III. Classification of Microbial Lipases................................................................................... 769 IV. Production, Isolation, and Purification.............................................................................. 773

A. Lipase Production...................................................................................................... 773 1. Effect of Nutritional Factors .............................................................................. 773 2. Effect of Physical Factors .................................................................................. 774

B. Isolation and Purification .......................................................................................... 775 V. Assay of Lipases ............................................................................................................... 776

A. Review of Emulsion Systems ................................................................................... 776 B. Normal-Phase Emulsions .......................................................................................... 777 C. Invert Emulsions ....................................................................................................... 777 D. Microemulsion: Reverse Micelles............................................................................. 778

1. Hydrolysis .......................................................................................................... 778 2. Transesterification .............................................................................................. 778

VI. Properties and Reactions ................................................................................................... 779 A. Structure .................................................................................................................... 779

1. Animal Lipases................................................................................................... 779 2. Fungal Lipases ................................................................................................... 780 3. Bacterial Lipases ................................................................................................ 780

B. Interfacial Activation and the Hydrolytic Reaction .................................................. 780 C. Activation=Inhibition................................................................................................. 782 D. Selectivity.................................................................................................................. 783 E. Immobilization .......................................................................................................... 786

VII. Industrial Applications ...................................................................................................... 789 A. General Uses ............................................................................................................. 789 B. New Lipases=Modification of Known Lipases ......................................................... 789 C. Production Synthesis=Modification........................................................................... 790

VIII. Summary ........................................................................................................................... 794 References ..................................................................................................................................... 794

Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) are enzymes that catalyze the reversible hydrolysis of triacylglycerols (TAGs) under natural conditions. Widely distributed in animals, plants, and microbes, lipases differ from other esterases and are unique in that their activity is

and is enhanced at the (oil)–water interface; that is, they exhibit ‘‘interfacial activation.’’ Optimum activities are obtained in systems such as emulsions, where high surface areas of the substrate can be obtained. Lipases are active not only in normal-phase emulsions where the substrate is emulsified into an aqueous system (oil-in-water), but also they are also active, often more active, in invert (water-in-oil) emulsions and in reverse micelle systems containing an organic solvent solution of the substrate. Furthermore, lipases are exceedingly versatile in that they can also catalyze transesterification reactions and the stereospecific synthesis of esters, and they can act on a broad range of substrates.