Extracellular Lipase Purification from a Marine Planomicrobium sp. MR23K and Productivity Optimization in a Pilot-Scale Submerged Bioreactor

Abstract

A halotolerant Planomicrobium species with remarkable lipase activity, isolated from the sediments of a mangrove, was investigated for the lipase purification, yield and production improvement. The enzyme purification was increased by 12.86-folds using a two-step purification process by ammonium sulfate precipitation and gel filtration chromatography. Subsequently, a submerged fermentation was optimized for the maximum lipase production using a response surface method (RSM). Several variables, comprising 8 nutritional variables along with pH, temperature and agitation speed were screened for the effective ones by Placket–Burman design (PBD). The effective variables were further examined for their optimum levels for the enzyme production using a central composite design (CCD). NaCl (1.28 % w/v), glucose (1.20 % w/v), olive oil (1.35 % w/v), peptone (0.69 % w/v) and pH (7.8) were found to be effective in maximizing the enzyme productivity in a lab scale (10.08 U/ml of cell-free supernatant) and a 10 l fermenter (9.89 U/ml). The results suggested that the model is accurate and consistent in predicting the best condition. Therefore, the strain under this specific fermentation condition promises a good prospect for a large-scale lipase production.