Estudo de imobilização da lipase do tipo B de Candida antarctica em silicato mesoporoso nanoestruturado (SBA‑15) visando a aplicação em reações de elevado interesse industrial
Dissertation (Ms) 24/02/2016
Nathalia Saraiva Rios
A recombinant Candida antarctica lipase B expressed in Pichia pastoris by insertion of an external DNA (LIPB) was immobilized in nanostructured mesoporous silicas of SBA-15 type by physical adsorption (SBA-15-LIPB) and covalent attachment (SBA-15- APTES-GA-LIPB e SBA-15-APTES-DVS-LIPB). Influence of contact time enzymesupport and the medium pH were evaluated to the production of biocatalysts. The thermal stability of immobilized enzymes were evaluated and the results showed that the SBA-15-APTES-GA-LIPB has the best thermal stability with t1/2 = 36,91 min while the SBA-15-APTES-DVS-LIPB has t1/2= 11,83 min and the SBA-15-LIPB has t1/2= 8,5 min, at 50 ºC. However, the SBA-15-LIPB has high stability in organic solvents than the biocatalysts produced by covalent attachment. Therefore, the biocatalyst SBA-15- LIPB (Optimized conditions: 100 % of the recovery activity an 1 hour of contact time, pH 7) was applied in a model esterification reaction in the short chain esters synthesis, the methyl and ethyl butyrate. The results showed that in optimized conditions of esterification (temperature: 37 ᵒC, solvent type: hexane for the methyl butyrate and isooctane for ethyl butyrate synthesis, substrate concentration: 0,2 mol/L, molar ratio of substrates 1:1, time of reaction: 12 h) the conversions were: 79.25 % for the methyl butyrate synthesis and 86.52 % for ethyl butyrate synthesis. The biocatalyst SBA-15- LIPB exhibited high activity and operational stability on the methyl and ethyl butyrate synthesis by esterification after five and six successive cycles of 12 h each, respectively. The biocatalysts SBA-15-APTES-GA-LIPB and SBA-15-APTES-DVS-LIPB were applied in a model hydrolysis reaction in the kinetic resolution of the phenylethyl acetate. The experimental data showed that were obtained positive results for both biocatalysts, but the biocatalyst SBA-15-APTES-GA-LIPB was more efficient, producing enantiomeric excess 99 %, conversion 50 % and enantiomeric ratio 1057.
