Extrolites ofWallemia sebi, a very common fungus in the built environment

Abstract

Wallemia sebi has been primarily known as a spoilage fungus of dried, salted fish and other foods that are salty or sweet. However, this fungus is also very common in house dust. The health effects of chronic exposure to mold and dampness are known to be associated with both allergens and various inflammatory compounds, including the secondary metabolites of building associated fungi and their allergens. IgE sensitization to W. sebi has been long reported from housing and occupational exposures. However, its allergens have not been described previously. Strains from food have been reported to produce a number of compounds with modest toxicity. Strains from the built environment in Canada produced a number of metabolites including the known compound walleminone and a new compound 1-benzylhexahydroimidazo [1,5-α] pyridine-3,5-dione which we call wallimidione. Based on an in silico analysis, wallimidione is likely the most toxic of the metabolites reported to date from W. sebi. We found that the primary human antigen of W. sebi is a 47 kDa excreted cellulase present in high concentrations in W. sebi arthrospores. This species is a basidiomycete and, unsurprisingly, the antigen was not found in extracts of other fungi common in the built environment, all ascomycetes.

Production of Secondary Metabolites in Extreme Environments: Food- and Airborne Wallemia spp. Produce Toxic Metabolites at Hypersaline Conditions

“…include indole alkaloids, such as tryptophol and tryptophol acetate [26, 28], which are derived from the amino acid tryptophan. These aromatic alcohols are important signalling molecules that play a significant role in the control of morphogenesis in the fungal cells [59].…”

“…sebi represented the only known species of the genus Wallemia [19], thus reports regarding secondary metabolites ( Table 1 ) were limited only to this species. Wallemia sebi was reported to produce several bioactive metabolites, such as toxic wallimidione [26], walleminone and walleminol [27–29], UCA 1064-A and UCA 1064-B [30, 31] and pigments [32, 33]. Walleminol (named also walleminol A) has been detected in food (jam and cake), both naturally and artificially contaminated with W .…”

“…Walleminol has an LD 50 of 40 μg mL -1 for brine shrimp and Tetrahymena pyriformis , and a minimum inhibitory dose of 50 μg mL -1 for rat liver cells and baby hamster kidney cells [27]. Walleminol is usually difficult to detect [26], due to natural interconversion to walleminone [28], previously designated as walleminol B [27]. In Toxtree the toxicity of walleminone was predicted ad modest [26].…”

“…Walleminol is usually difficult to detect [26], due to natural interconversion to walleminone [28], previously designated as walleminol B [27]. In Toxtree the toxicity of walleminone was predicted ad modest [26]. UCA 1064-A and UCA 1064-B exhibit antitumor activity against mouse mammary tumour model, antifungal activity against Saccharomyces cerevisiae , antimicrobial activities against Gram-positive bacteria at 40 μg mL -1 , and antiproliferative activities against HeLa S3 cells.…”

Halotolerance (ionic NaCl) and chaotolerance (ionic MgCl2) of the human pathogen Wallemia mellicola isolated, for the first time, from indoor air in Poland

“…Species in the W. sebi complex produce toxic metabolites, i.e., walleminol A, walleminone [7,8], azasteroid [9], and wallimidione [10], which may cause subcutaneous infections referred to as phaeohyphomycosis [11]. Some reports have suggested that species in this complex could be the causal agents for lung disease in farmers in Scandinavia, France, and China and allergic activity [12].…”