Pretreatment of an Induced Mycelium-Bound Lipase from Aspergillus niger MYA 135 Improves Its Hydrolytic and Synthetic Activity

Whole-cell enzymes have been used as biocatalysts in a variety of reactions, such as free fatty acid production and the synthesis of fatty acid esters. In the present study, enzyme pretreatments with PEG, MES, Tween 80, Saponine, MgCl 2 ·H 2 O, CaCl 2 and different pH values were evaluated by using the Plackett–Burman statistical design to improve both the hydrolytic and synthetic activity of an induced mycelium-bound lipase from Aspergillus niger MYA 135. Interestingly, the preincubation at pH 4 had a significant effect on both the hydrolytic and transesterification activity, demonstrating the influence of the correct ionisation state on these activities. Meanwhile, the enzyme pretreatment with MgCl 2 for in situ water activity control positively affected the esterification catalyst. Thus, compared with the control without pretreatment, the hydrolytic and the transesterification activities increased to 60.1 and 60.8 %, respectively, and with respect to the esterification reaction, the conversion was improved 2.33 times. Based on these results, by applying a simple pretreatment to the biocatalyst, the catalyst’s activity toward hydrolysis and synthesis was enhanced. Graphical Abstract