Virulence related traits in yeast species associated with food; Debaryomyces hansenii , Kluyveromyces marxianus , and Wickerhamomyces anomalus

There is an increase in the number of human infections associated with yeast species that are also known to be involved in processing foods such as Saccharomyces cerevisiae, Debaryomyces hansenii, Wickerhamomyces anomalus, or Kluyveromyces marxianus. Clinical strains of S. cerevisiae have been well studied over the years and much is known regarding their virulence. However, very little is known about the virulent potential of strains of D. hansenii, W. anomalus, or K. marxianus. In this study, several factors related to virulence in a collection of clinical and food/environmental isolated strains of each species were determined. Physiological factors were looked at as well as parameters related to infection in an epithelial cell culture model and mortality in the invertebrate model Galleria mellonella. The results revealed that all of the evaluated K. marxianus strains (except for one strain) are positive in most physiological virulent factors, and also in the epithelial cell culture parameters. Wickerhamomyces anomalus strains produce 10 times higher levels of mortality in G. mellonella besides showed intermediate levels according to virulent factors. In the case of D. hansenii, all the tested strains are positive, but only in a single and different virulent parameter without a common pattern. Thus, our study reveals that some strains of K. marxianus and W. anomalus, could be a potential risk for human health and that the food/ environmental strains could be the origin of infections.

Automated summary

The number of human infections associated with yeast species involved in food processing is increasing, with some strains posing a potential risk for human health.