Hydrolysis of oils by using immobilized lipase enzyme: A review

Olive-mill wastewaters: a promising substrate for microbial lipase production

The present study investigated the valorization of olive-mill wastewater (OMW) by its use as a possible growth medium for the microbial production of extra-cellular lipase. To this end, strains of Geotrichum candidum (NRRL Y-552 and Y-553), Rhizopus arrhizus (NRRL 2286 and ISRIM 383), Rhizopus oryzae (NRRL 6431), Aspergillus oryzae (NRRL 1988 and 495), Aspergillus niger (NRRL 334), Candida cylindracea (NRRL Y-17506) and Penicillium citrinum (NRRL 1841 and 3754, ISRIM 118) were screened. All strains were able to grow on the undiluted OMW, producing extra-cellular lipase activity. C. cylindracea NRRL Y-17506 showed the highest lipase activity on all the typologies of OMW used. Its lipase production on OMW was markedly affected by the type of nitrogen source and was induced by the addition of olive oil. The highest activity (9.23 IU ml(-1)) of the yeast was obtained on OMW supplemented with NH(4)Cl (2.4 g l(-1)) and olive oil (3.0 g l(-1)).

Pretreatment of lipase with soybean oil before immobilization to prevent loss of activity

Lipase was pretreated with soybean oil in order to allow fatty acids to bond to the active site before immobilization. This pretreated lipase exhibited steric hindrance around the active site such that during immobilization, covalent bonds were formed between the carrier and the lipase region far from the active site. The activity of the pretreated lipase immobilized covalently on a silica gel was 530 U/g-matrix, which is 16 times higher than that of the immobilized non-pretreated lipase. In addition, the immobilized lipase activity was maintained at levels exceeding 90% of its original activity after 10 reuses.