Extracellular Alkaline Lipase from a Novel Fungus Curvularia sp. DHE 5: Optimisation of Physicochemical Parameters, Partial Purification and Characterisation

Dina Helmy El-Ghonemy1*small orcid_display_4pp, Mamdouh S. El-Gamal2small orcid_display_4pp, Amir Elsayed Tantawy1small orcid_display_4pp and Thanaa Hamed Ali1small orcid_display_4pp

1Department of Microbial Chemistry, Genetic Engineering and Biotechnology Division, National Research Centre, 33 El Buhouth St., EG-12 622 Giza, Egypt
2Botany and Microbiology Department, Faculty of Science, Al-Azhar University, EG-11 884 Nasr City, Egypt

Article history:
Received August 18, 2016
Accepted April 4, 2017

Key words:
lipase, Curvularia sp. DHE 5, optimisation of culture conditions, agro-industrial residues, lipase characterisation

Thirty isolated fungal strains were screened for lipase production using Phenol Red plates, containing tributyrin as lipidic substrate, and a novel fungus identified genetically as Curvularia sp. DHE 5 was found as the most prominent strain. Various agro-industrial substrates were evaluated as inert supports for lipase production in solid-state fermentation. The highest yield of lipase ((83.4±2.2) U/g on dry mass basis) was reported with wheat bran medium after seven days of fermentation at pH=7.0, temperature of 30 °C, 70 % moisture content, inoculum size of 1.27·107 spore/mL and 2 % olive oil as an inducer. Supplementation of the medium with 0.05 % KCl as an ion source further increased lipase production to (88.9±1.2) U/g on dry mass basis. The enzyme was partially purified through ammonium sulphate fractionation (40 %) followed by dialysis, and its optimum pH and temperature were reported at 8.0 and 50 °C, respectively, with remarkable pH and thermal stability.

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