Purification and partial characterization of a lipase from Brevibacillus agri MIR-E12

NIETO PEÑARVER CG, LOTO F DEL V, ROMERO CM, CASTRO GR, BAIGOR MD

Tafi del Valle Tucumán. Argentina

Jornada; XXVI ANNUAL SCIENTIFIC MEETING TUCUMAN BIOLOGY ASSOCIATION; 2009

Microbial lipases show potential for the development of commercial applications due to their stability, selectivity and wide substrate range. The objective of this work was the characterization of a lipase from the bacterium Brevibacillus agri MIR-E12, purified from cell-free supernatant. The strain, identified by rDNA 16S sequencing, was cultured aerobically in LB broth at 37¨¬C for 24 hs. After a first precipitation of the cell-free supernatant with ammonium sulphate and a second precipitation step with acetone, the protein extract was fractioned by anion exchange chromatography and the enzyme was purified to homogeneity. The lipase possesses a Km of 0.17 mM and a Vmax of 0.935 nmol min-1 ¥ìg-1. We analyzed the effect of different cations, organic solvents and tensioactive agents on the enzyme activity. We found that B. Agri MIR-E12 produces a lipase of 30 KDa, which shows an optimal temperature of 40¨¬C and an optimal pH of 9. Although the enzyme is not thermostable, the addition of Ca2+ improved thermal stability.It shoud be noted that dimethyl sulfoxide increased lipase activity, which is in contrast with the decreases produced by Tween 80, Tween 20, SDS and Triton X100. Among the cations, a noteworthy feature was the increase caused by Ca2+ that correlates with the diminished values measured after supplementation with EDTA. The results showed that B. agri MIR-E12 produces a lipase with important biotechnological features.