Purification of an organic solvent-tolerant lipase from Aspergillus niger MYA 135 and its application in ester synthesis

An organic solvent-tolerant lipase from olive oil-induced Aspergillus niger MYA 135 supernatant was purified using two methods: electroelution and ion-exchange chromatography. With electroelution purification was 8.4-fold and recovery 47% and with ion-exchange 16.6-fold and 53.4%, respectively. The purified enzyme showed a prominent single band with SDS-PAGE and was a monomeric protein of 68 kDa. The isoelectric point (pI) of the lipase was 5.1 and optimum pH and temperature for activity were 7.0 and 37 °C, respectively. The lipase showed affinity for esters with long acyl chains, with a Km of 0.99 mM for C18. Substrate specificity of the immobilized lipase was highest for C18 among the various α- and β-naphthyl esters assayed. Substrate specificity agreed with kinetics parameters of long-chain fatty acids (C18). Transesterification activity of the A. niger MYA 135 lipase indicates that it could be a potential biocatalyst for biodiesel production.