Abstract
•PHB has showed an alternative in the purification of produced lipase from broth.•The catalytic properties of the lipase were determined in olive oil hydrolysis.•Ethyl linoleate synthesis by esterification was optimized by factorial design.•After 6 cycles of ester synthesis, the biocatalyst retained 93% of its activity.
The present study reports the production of an extracellular lipase from Geotrichum candidum by submerged fermentation using cottonseed oil as inductor agent and its immobilization on poly-hydroxybutyrate (PHB) particles via physical adsorption. The catalytic properties of the biocatalyst prepared were determined in aqueous (hydrolysis of olive oil emulsion) and organic (ethyl linoleate synthesis) media. In the enzyme production, maximum hydrolytic activity of 22.91IU/mL at 30°C and pH 5.2 was reached after 48h of cultivation. A single protein band with an apparent molecular mass of 65kDa was detected by SDS-PAGE analysis. The biocatalyst prepared by offering 75mL of crude enzymatic extract (without cells) per gram of support exhibited maximum hydrolytic activity of 404.4±2.3IU/g at 37°C and pH 7.0, with a recovered activity percentage of around 40% and an immobilization yield of 59%. The optimal pH and temperature for both soluble and immobilized enzyme in the hydrolysis reaction was 8.0 and around 37–40°C. The biocatalyst was more thermally stable than the crude enzymatic extract at 35°C in 8h (46.2% and 23.7%, respectively) and slightly more stable at 45°C in 40min (47.5% and 35.2%, respectively). In the esterification reaction, around 70% ester conversion was reached after 2h of reaction under experimental conditions previously optimized by Central Composite Rotatable Design (CCRD). The biocatalyst retained 93% of its initial esterification activity after 6 successive cycles of esterification reaction. This biocatalyst is a promising one to catalyze reactions in aqueous and organic media.