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

Dina Helmy El-Ghonemy,Mamdouh El-Gamal,Thanaa Hamed Ali,Amir Elsayed Tantawy

doi:10.17113/ftb.55.02.17.4958

Dina Helmy El-Ghonemy, Mamdouh El-Gamal + Show 2 more

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https://doi.org/10.17113/ftb.55.02.17.4958

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Abstract

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.

Highlights

Lipases (EC 3.1.1.3) catalyse the hydrolysis of acyl glyc erol to glycerol, mono- and diacylglycerol
In the rapid qualitative tributyrin Phenol Red agar plate (TPRA) method, out of thirty fungal strains screened for extracellular lipase activity, seventeen gave positive test result with various degrees depending on the intensity of the produced yellow colour
Yellow colour can be interpreted as the consequence of pH changes in the media caused by increased level of fatty acids due to their release from triglycerides by the action of lipase

Summary

Introduction

Lipases (EC 3.1.1.3) catalyse the hydrolysis of acyl glyc erol to glycerol, mono- and diacylglycerol. They catalyse under certain conditions the synthesis of esters through transesterification, thioesterification and amin olysis [1]. Lipases find application in different industrial sectors, i.e. synthesis of biosurfactants, detergent formulations, oleochemical and agrochemical in dustries, paper manufacturing and pharmaceutical proces sing [2]. Fungal lipases are generally preferred for industrial application because they are usually secreted extracellularly, which enables simple extraction from the fermentation medium. Among major fungal species capable of producing high levels of lipase are Fusarium solani [4], Rhizopus oligosporus [5] and Trichoderma harzianum [6]

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