COMPARISON OF THE ACTIVITY OF TRANSESTERIFICATION OF LIPASES THROUGH THE para-NITROFENIL PALMITATO ASSAY OF TWO GRAM (-) BACILLUS ISOLATED OF SOILS

Abstract

The goal of this work was to evaluate the lipases activity of two previously isolated bacterias gram(-) with the assay of para-Nitrophenyl Palmitate (pNPP). The experiments were carried out with dried whole-cells and lyophilized supernatant from two strains grown in two different media. The strains CN-123 and MMS-3 were cultivated in nutrient broth (CN) and a mineral media added with sucrose, respectively. Both media were adjusted at pH 7 and 5% (w/w) of waste cooking oil and incubated at 30°C for 32 h. The media cultures were centrifuged and the supernatants obtained were lyophilized (SL) and the cell pellets were air dried (CS). Samples of 20 mg of each SL and CS were taken for reaction procedure and samples were taken at reaction at times of: 0.5, 5, 10, 20, 40 and 60 minutes. In case of whole cells, the quantity of para-Nitrophenol (pNP) was apparently constant during along the experiment for both strains and both media. However, most of the activity of lipase (releasing of pNP) occurred at the beginning of the experiment. The maximal activity was quantifying in the strain MMS-3. In case of SL, the lipase activity was minor compared to that determined in whole cells. Our results demonstrated that the liberation of pNP occurred during the beginning of the experiments. Hence the lipase activity is high during the first times of reaction. These results demonstrated the effectiveness of pNPP assay for quantification and comparison lipase activities in the screening of different enzymes with novel characteristics.