A gene encoding a carboxylesterase produced by Geobacillus thermoleovoras CCR11 was cloned in the pET-3b cloning vector, sequenced and expressed in Escherichia coli BL21(DE3). Gene sequence analysis revealed an open reading frame of 750 bp that encodes a polypeptide of 250 amino acid residues (27.3 kDa) named CaesCCR11. The enzyme showed its maximum activity at 50 °C and pH 5-8, with preference for C4 substrates, confirming its esterase nature. It displayed good resistance to temperature, pH, and the presence of organic solvents and detergents, that makes this enzyme biotechnologically applicable in the industries such as fine and oleo-chemicals, cosmetics, pharmaceuticals, organic synthesis, biodiesel production, detergents, and food industries. A 3D model of CaesCCR11 was predicted using the Bacillus sp. monoacyl glycerol lipase bMGL H-257 structure as template (PBD code 3RM3, 99 % residue identity with CaesCCR11). Based on its canonical α/β hydrolase fold composed of 7 β-strands and 6 α-helices, the α/β architecture of the cap domain, the GLSTG pentapeptide, and the formation of distinctive salt bridges, we are proposing CaesCCR11 as a new member of family XV of lipolytic enzymes.

Lipases are the versatile biological catalysts used in a wide range of commercial synthetic applications. Microbial lipases have been widely used in the pharmaceutical, food, textile, oleochemical, paper, and bioenergy industries, in the composition of detergents, and in the production of polymers and enantiomerically pure chemical intermediates. Lipases have a unique lid opening mechanism that makes them interesting biocatalysts to catalyze reactions in hydrophobic environments. Water insoluble substrates have also been efficiently transformed by lipases in organic solvents. The use of lipases in industrial processes could be limited by the cost of their production, the difficulties in their recovery and disposal, or by the harsh conditions of some processes that could inactivate or denature the protein. The immobilization of enzymes helps overcome these physical and economical drawbacks, making the catalyst more active, stable, and reusable, resulting in the reduction of costs and of contaminating and harmful byproducts. Polypropylene has unique properties that aid in the activation of the lid opening mechanism and improve the catalytic efficiency of immobilized lipases. The aim of this review is to present an overview of the uses of polypropylene as a support for immobilization of lipolytic enzymes, the study of the immobilization procedure conditions, the characteristics of the immobilized enzymes, and the perspectives of their use in the future as a powerful tool in sustainable industry.

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