Cross-linked enzyme aggregates (CLEAs) were prepared from several precipitant agents using glutaraldehyde as a cross-linking agent with and without BSA, finally choosing a 40% saturation of ammonium sulfate and 25mM of glutaraldehyde. The CLEAs obtained under optimum conditions were biochemically characterized. The immobilized enzyme showed higher thermal activity and a broader range of pH and organic solvent tolerance than the free enzyme. Arylesterase from Gluconobacter oxydans showed activity toward cephalosporin C and 7-aminocephalosporanic acid. The CLEAs had a Kcat/K-M of 0.9M(-1)/S-1 for 7-ACA (7-aminocephalosporanic acid) and 0.1M(-1)/S-1 for CPC (cephalosporin c), whereas free enzyme did not show a typical Michaelis-Menten kinetics. (c) 2015 American Institute of Chemical Engineers Biotechnol. Prog., 32:36-42, 2016