title: Low water activity induces the production of bioactive metabolites in halophilic and halotolerant fungi.
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.
authors.affiliation: Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana, Slovenia. kristina.sepcic@bf.uni-lj.si
authors.forename: Kristina
authors.initials: K
authors.lastname: Sepcic
authors.forename: Polona
authors.initials: P
authors.lastname: Zalar
authors.forename: Nina
authors.initials: N
authors.lastname: Gunde-Cimerman
mesh_terms: D000110:Acetylcholinesterase; D000222:Adaptation, Physiological / Q000187:drug effects*; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D003470:Culture Media; D055808:Drug Discovery; D017753:Ecosystem; D005658:Fungi / Q000378:metabolism*; D006461:Hemolysis; D046448:Ice Cover / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D009792:Oceans and Seas; D055049:Salt Tolerance; D012623:Seawater / Q000382:microbiology; D012965:Sodium Chloride / Q000378:metabolism*; D014867:Water / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D014867:Water; D012965:Sodium Chloride; D000110:Acetylcholinesterase