Wallemiomycetes

chaotolerance, growth temperature regimes, extracellular enzyme activity profiles, and secondary metabolite patterns.^[1][5] They are typically isolated from low-moisture foods (such as cakes, bread, sugar, peanuts, dried fish), indoor air dust, salterns and soil.^[1] W. sebi is thought to be one of the causes of the hypersensitivity pneumonitis known as the farmer's lung disease,^[6] but since the other species were recognised and separated from W. sebi only recently, their role in the disease cannot be excluded.^[1]

basidomycetous fungi, and xerotolerant fungi are also able to grow in regular growth media with normal water activity (unlike, for example, halophilic Archaea).^[7] However, species from the genus Wallemia are an exception to both of these rules: all species can tolerate high concentrations of sugars and salts (W. ichthyophaga grows even in media saturated with sodium chloride), while W. muriae and W. ichthyophaga cannot be cultivated unless the water activity of the medium is lowered.^[1]

secondary metabolic compounds, including walleminol, walleminone, wallemia A and C, and azasteroid UCA1064-B.^[8] A comprehensive research on other species of the class discovered that secondary metabolites are consistently produced by Wallemiomycetes and their production is – contrary to common presumptions – increased as a response to increasing NaCl concentration. In particular an increase in NaCl concentration from 5% to 15% in the growth media increased the production of the toxic metabolites wallimidione, walleminol and walleminone.^[9]