Intracellular-to-extracellular localization switch of acidic lipase in Enterobacter cloacae through multi-objective medium optimization: aqueous two-phase purification and activity kinetics.

Abstract

As physiological impairments that require replacement therapy continue to increase, so also does the need for improved production of acidic lipase from new microbial sources. Enterobacter cloacae strain UCCM 00116 produced a novel acidic lipase in kernel oil-processing waste-basal broth with 0.023:1 extracellular: intracellular localization ratio. This research re-directed enzyme localization to the extracellular milieu to reduce recovery cost using multi-objective response surface optimization of medium parameters. Results revealed a 1:0.32 extracellular:intracellular lipase ratio. Product formation kinetics, modeled by the Luedeking-Piret function, showed a significant switch from a completely growth-associated intracellular production to a predominantly non-growth-associated extracellular localization through medium optimization. Aqueous two-phase system purification conditions extracted 95.22% lipase with 72.36 purity, a Vmax of 370.37 µmolmin-1, and a Km of 0.63 mmol. Enzyme activity was enhanced by K+ and Ca2+ ions, stable in many organic solvents, except acetone, and had pH and temperature optima at 2.5-3.5 and 50°C, respectively.