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BioMed Research International
Volume 2014 (2014), Article ID 108913, 11 pages
http://dx.doi.org/10.1155/2014/108913
Research Article

Lipolytic Potential of Aspergillus japonicus LAB01: Production, Partial Purification, and Characterisation of an Extracellular Lipase

1Cell Signaling, Nanobiotechnology and Enzymology Laboratory, Federal University of Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil
2Laboratory of Applied Microbiology, Federal University of Minas Gerais 31270-901, Belo Horizonte, MG, Brazil

Received 16 May 2014; Revised 31 August 2014; Accepted 2 September 2014; Published 29 October 2014

Academic Editor: Yunjun Yan

Copyright © 2014 Lívia Tereza Andrade Souza et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Lipolytic potential of Aspergillus japonicus LAB01 was investigated by describing the catalytic properties and stability of a secreted extracellular lipase. Enzyme production was considered high under room temperature after 4 days using sunflower oil and a combination of casein with sodium nitrate. Lipase was partially purified by 3.9-fold, resulting in a 44.2% yield using ammonium sulphate precipitation (60%) quantified with Superose 12 HR gel filtration chromatography. The activity of the enzyme was maximised at pH 8.5, and the enzyme demonstrated stability under alkaline conditions. The optimum temperature was found to be 45°C, and the enzyme was stable for up to 100 minutes, with more than 80% of initial activity remaining after incubation at this temperature. Partially purified enzyme showed reasonable stability with triton X-100 and was activated in the presence of organic solvents (toluene, hexane, and methanol). Among the tested ions, only Cu2+, Ni2+, and Al3+ showed inhibitory effects. Substrate specificity of the lipase was higher for C14 among various p-nitrophenyl esters assayed. The and values of the purified enzyme for p-nitrophenyl palmitate were 0.13 mM and 12.58 umol/(L·min), respectively. These features render a novel biocatalyst for industrial applications.