RESUMEN
The recombinant lipase LipMatCCR11 from the thermophilic strain Geobacillus thermoleovorans CCR11 was applied in the synthesis of n-butyl caproate via transesterification in hexane and xylene. The short chain flavour ester was obtained by alcoholysis from ethyl caproate and n-butyl alcohol and acidolysis from n-butyl butyrate and caproic acid. This enzyme was also used in the condensation reaction from caproic acid and n-butanol. The conversion percentages at equilibrium (Xe) were similar to those obtained with Candida antarctica lipase fraction B (CAL-B) in the same reaction conditions, while lower conversion velocities (k) were attained. LipMatCCR11 reached high conversion percentages in either hexane or xylene as organic media (> 63%); the enzyme was also able to catalyze the aminolysis reaction of ethyl caproate with benzyl amine in hexane obtaining a conversion percentage > 62%.
Asunto(s)
Caproatos/metabolismo , Geobacillus/enzimología , Lipasa/metabolismo , Proteínas Recombinantes/metabolismo , Alquenos/química , Caproatos/química , Esterificación , Geobacillus/genética , Cinética , Lipasa/química , Lipasa/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Xilenos/químicaRESUMEN
A partially purified lipase produced by the thermophile Geobacillus thermoleovorans CCR11 was immobilized by adsorption on porous polypropylene (Accurel EP-100) in the presence and absence of 0.1% Triton X-100. Lipase production was induced in a 2.5% high oleic safflower oil medium and the enzyme was partially purified by diafiltration (co. 500,000 Da). Immobilization conditions were established at 25 degrees C, pH 6, and a protein concentration of 0.9 mg/mL in the presence and absence of 0.1% Triton X-100. Immobilization increased enzyme thermostability but there was no change in neither the optimum pH nor in pH resistance irrelevant to the presence of the detergent during immobilization. Immobilization with or without Triton X-100 allowed the reuse of the lipase preparation for 11 and 8 cycles, respectively. There was a significant difference between residual activity of immobilized and soluble enzyme after 36 days of storage at 4 degrees C (P < 0.05). With respect to chain length specificity, the immobilized lipase showed less activity over short chain esters than the soluble lipase. The immobilized lipase showed good resistance to desorption with phosphate buffer and NaCl; minor loses with detergents were observed (less than 50% with Triton X-100 and Tween-80), but activity was completely lost with SDS. Immobilization of G. thermoleovorans CCR11 lipase in porous polypropylene is a simple and easy method to obtain a biocatalyst with increased stability, improved performance, with the possibility for re-use, and therefore an interesting potential use in commercial conditions.