Microbial 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 from Pseudomonas sp. In the present study, a purified alkaline thermoalkalophilic extracellular lipase of Pseudomonas aeruginosa MTCC-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 various p-nitrophenyl acyl esters varying in their C-chain lengths. The bound lipase showed optimal hydrolytic activity towards p-nitrophenyl palmitate (p-NPP) at pH 8.5 and temperature 45 degrees C. The hydrolytic activity of the hydrogel-bound lipase was markedly enhanced by the presence of Hg2+, Fe3+, and NH4+ salt ions in that order. The hydrogel-immobilized lipase (25 mg) was used to perform esterification in various n-alkane(s) that resulted in similar to 84.9 mM of methyl acrylate at 45 degrees C in n-heptane under shaking (120 rpm) after 6 h, when methanol and acrylic acid were used in a ratio of 10 mM:100 mM, respectively. Addition of a molecular sieve (3 angstrom x 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 mM of ester after 10th cycle of reuse. (c) 2007 Wiley Periodicals, Inc.