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Low Water Activity Induces the Production of Bioactive Metabolites in Halophilic and Halotolerant Fungi
Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana, Slovenia
* Author to whom correspondence should be addressed.
Received: 8 November 2010; in revised form: 15 December 2010 / Accepted: 22 December 2010 / Published: 27 December 2010
Abstract: The aim of the present study was to investigate indigenous fungal communities isolated from extreme environments (hypersaline waters of solar salterns and subglacial ice), for the production of metabolic compounds with selected biological activities: hemolysis, antibacterial, and acetylcholinesterase inhibition. In their natural habitats, the selected fungi are exposed to environmental extremes, and therefore the production of bioactive metabolites was tested under both standard growth conditions for mesophilic microorganisms, and at high NaCl and sugar concentrations and low growth temperatures. The results indicate that selected halotolerant and halophilic species synthesize specific bioactive metabolites under conditions that represent stress for non-adapted species. Furthermore, adaptation at the level of the chemical nature of the solute lowering the water activity of the medium was observed. Increased salt concentrations resulted in higher hemolytic activity, particularly within species dominating the salterns. The appearance of antibacterial potential under stress conditions was seen in the similar pattern of fungal species as for hemolysis. The active extracts exclusively affected the growth of the Gram-positive bacterium tested, Bacillus subtilis. None of the extracts tested showed inhibition of acetylcholinesterase activity.
Keywords: hypersaline environments; black yeast; NaCl; secondary metabolites; hemolysis; antibacterial activity
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Sepcic, K.; Zalar, P.; Gunde-Cimerman, N. Low Water Activity Induces the Production of Bioactive Metabolites in Halophilic and Halotolerant Fungi. Mar. Drugs 2011, 9, 43-58.
Sepcic K, Zalar P, Gunde-Cimerman N. Low Water Activity Induces the Production of Bioactive Metabolites in Halophilic and Halotolerant Fungi. Marine Drugs. 2011; 9(1):43-58.
Sepcic, Kristina; Zalar, Polona; Gunde-Cimerman, Nina. 2011. "Low Water Activity Induces the Production of Bioactive Metabolites in Halophilic and Halotolerant Fungi." Mar. Drugs 9, no. 1: 43-58.