Purification and partial characterization of the thermophilic lipase produced by Bacillus licheniformis

ROMERO, CINTIA MARIANA; LOTO, FLAVIA; PERA, LICIA MARÍA; ABDULHAMID, MARÍA BELÉN; BAIGORI, MARIO DOMINGO

San Miguel de Tucumán

Congreso; VII Congreso Argentino de Microbiología General "SAMIGE del BICENTENARIO"; 2011

Lipases (triacylglycerol acylhydrolases; EC 3.1.1.3) constitute a group of enzymes defined as carboxylesterases that catalyze the hydrolysis (and synthesis) of long chain acylglycerols at the lipid-water interface. In recent years, lipases have received considerable attention with regard to industrial application, since they have a number of unique characteristics: substrate specificity, regio-specificity and chiral selectivity. Given that such reactions are sometimes performed most efficiently at elevated temperatures and in organic solvents, converging attempts have been made to find thermostable lipases which would have advantages over labile enzymes in such applications. In recent years, a number of thermophilic microorganisms producing thermoactive lipases and esterases have been purified and characterized. In this study, we describe the purification and characterization of a thermophilic lipase produced by the thermophilic strain Bacillus licheniformis, isolated from a hot spring. Thermophilic Bacillus strains that were screened showed activity bands in native-PAGE indicating the production of extracellular lipase and/or esterase. The partial 16S rDNA sequencing of the Bacillus strain selected showed the highest homology (99%) with Bacillus licheniformis. This was chosen for lipase purification and characterization since it produced the highest lipase activity. The purification was performed with electroelution technique. Lipase was eluted from the polyacrylamide gel slices and the enzyme containing-solution was concentrated by vacuum. Purity was confirmed for the migration of a single band. This enzyme showed residual activities equal or above 100% after treatment for 1 h at: temperatures from 45 to 60°C, alkaline pH from 8 to 10 and non polar solvent (DMSO and n-hexane). Higher thermostability, higher activity at elevated temperatures, and more resistance to chemical denaturation are desirable properties of thermophilic lipases which make them ideal tools in industrial and chemical processes where relatively high reaction temperatures and/or organic solvents are used.