Lipid peroxidation in the fungus Curvularia lunata exposed to nickel
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ORIGINAL PAPER
Lipid peroxidation in the fungus Curvularia lunata exposed to nickel Katarzyna Paraszkiewicz • Przemysław Bernat Marcin Naliwajski • Jerzy Długon´ski
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Received: 5 December 2008 / Revised: 18 December 2009 / Accepted: 27 December 2009 / Published online: 3 January 2010 Ó Springer-Verlag 2010
Abstract The effect of Ni2? on fungal growth, cellular fatty acid profile and lipid peroxidation was studied (with an emphasis on the kinetics of these processes) in the strain of filamentous fungus Curvularia lunata. In the cultures supplemented with 0.2 and 0.6 mM Ni2? the lag phase was extended and the specific growth rate decreased, however, the maximum yield of biomass at the stationary phase reached, respectively, 97 and 27% of the control. The treatment with Ni2? changed the proportion of 18 C atom fatty acids, with the most significant decrease in the content of linoleic acid (18:2) followed by a rise in the degree of fatty acid saturation. In the mycelia exposed to Ni2? the levels of TBARS (lipid peroxidation products) increased and ranged between 156 and 823% over the control. The presented data reveal that the oxidative stress resulting, among others, in membrane lipid peroxidation is involved in the mechanisms of the nickel toxicity towards C. lunata and suggest that this fungus exhibits an ability to cope, to some extent, with the increased level of lipid peroxides. Keywords Curvularia lunata Fatty acids Filamentous fungi Lipid peroxidation Nickel
Communicated by Axel Brakhage. K. Paraszkiewicz P. Bernat J. Długon´ski (&) Department of Industrial Microbiology and Biotechnology, University of Ło´dz´, Banacha 12/16, 90-237 Lodz, Poland e-mail: [email protected] M. Naliwajski Department of Plant Physiology and Biochemistry, University of Ło´dz´, Banacha 12/16, 90-237 Lodz, Poland
Introduction Nickel is considered to be one of the major environmental pollutants, due to its toxic, allergic and carcinogenic potential (Kasprzak et al. 2003; Lu et al. 2005). Ions of this heavy metal have been reported to be capable of inhibiting the enzymes function, disturbing nucleic acids synthesis and inducing oxidative stress—the condition in which the levels of oxygen-free radicals, more generally known as reactive oxygen species (ROS), exceed the antioxidant capacity of the cells (Denkhaus and Salnikow 2002; Valko et al. 2006; Das and Buchner 2007). Polyunsaturated fatty acids are particularly sensitive to the attack caused by ROS and peroxidation of lipids generated by ROS leads to the formation of various cytotoxic products. Malondialdehyde (MDA)—a secondary lipid peroxidation product, along with the thiobarbituric acid reactive substances (TBARS) test, belongs to the most widely used assays for indexing lipid peroxidation (Garcia et al. 2005; Valavanidis et al. 2006). The involvement of nickel in the increased ROS production and peroxidation of lipids has been extensively investigated in plants as well as in animal and human cells (Seregin and Kozhevnikova 2006; Boisvert et al. 2007; Das and B
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