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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 25 mM 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/KM of 0.9 M(-1) /S(-1) for 7-ACA (7-aminocephalosporanic acid) and 0.1 M(-1) /S(-1) for CPC (cephalosporin c), whereas free enzyme did not show a typical Michaelis-Menten kinetics., (© 2015 American Institute of Chemical Engineers.)

Lactobacillus plantarum is a lactic acid bacterium that is encountered in an extensive range of foods such as fermented dairy products, meat, vegetables, and bakery products. Given the little molecular information available on the lipolytic activity of L. plantarum, the aim of this study was to clone, purify, and biochemically characterize the esterase coded by gene lp_0796 (Est0796). The esterase was cloned in pET28a and purified in two steps, using solid ammonium sulfate and His tag affinity chromatography. The molecular mass of the purified Est0796 was 28.7 kDa (by SDS-PAGE) and 26.6 kDa (by gel filtration chromatography), pointing to a monomeric structure. Est0796 showed maximum activity at pH 8.0 and 35 °C and toward shorter acyl chain lengths (C2-C4). The activity was resistant to organic solvents and cations, suggesting that this esterase may play a role in the fermentation of food products.