Properties of poly(AAc‐co‐HPMA‐cl‐EGDMA) hydrogel‐bound lipase ofPseudomonas aeruginosaMTCC‐4713 and its use in synthesis of methyl acrylate

Abstract

AbstractMicrobial lipases (E.C. 3.1.1.3) are preferred biocatalysts for the synthesis of esters in organic solvents. Various extracellular thermoalkaliphilic lipases have been reported fromPseudomonassp. In the present study, a purified alkaline thermoalkalophilic extracellular lipase ofPseudomonas aeruginosaMTCC‐4713 was efficiently immobilized onto a synthetic poly(AAc‐co‐HPMA‐cl‐EGDMA) hydrogel by adsorption and the bound lipase was evaluated for its hydrolytic potential towards variousp‐nitrophenyl acyl esters varying in their C‐chain lengths. The bound lipase showed optimal hydrolytic activity towardsp‐nitrophenyl palmitate (p‐NPP) at pH 8.5 and temperature 45°C. The hydrolytic activity of the hydrogel‐bound lipase was markedly enhanced by the presence of Hg2+, Fe3+, and NHsalt ions in that order. The hydrogel‐immobilized lipase (25 mg) was used to perform esterification in variousn‐alkane(s) that resulted in ∼ 84.9 mMof methyl acrylate at 45°C inn‐heptane under shaking (120 rpm) after 6 h, when methanol and acrylic acid were used in a ratio of 100 mM:100 mM, respectively. Addition of a molecular sieve (3Å × 1.5 mm) to the reaction system at a concentration of 100 mg/reaction vol (1 mL) resulted in a moderate enhancement in conversion of reactants into methyl acrylate (85.6 mM). During the repetitive esterification under optimum conditions, the hydrogel‐bound lipase produced 71.3 mMof ester after 10th cycle of reuse. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 183–191, 2007