Oxidative stress induced by the human microbiota yeast component as a micromycetes pathogenicity factor

The introduction of MALDI-ToF mass spectrometry into routine microbiological diagnostics has led to a widely extended list of identified microorganisms. This phenomenon also affected mycological studies. Rare basidiomycetes and ascomycetes began to be detected in various types of pathological material. It is often difficult to assess a role of isolated micromycetes in the pathogenesis of a certain disease. In addition to generally admitted pathogenicity factors, such as aggression enzymes, adhesive activity, and toxin formation, induction or inhibition of reactive oxygen species can play a prominent role in pathogenesis of infectious diseases. In our study, we evaluated the total prooxidant and total antioxidant activity of cultivated ascomycete and basidiomycete yeasts from the human intestinal mycobiome. The strains of micromycetes assessed here were obtained from a fecal culture study from patients with gastrointestinal tract pathology and healthy people undergoing a routine medical examination. Identification was carried out analyzing morphological, cultural, biochemical properties and confirmed by mass spectrometry. The total prooxidant and antioxidant activity was assessed by the induced or inhibited malondialdehyde formation during Tween-80 oxidation. It was found that the level of total prooxidant activity in Rhodotorula mucilaginosa, Geotrichum candidum, Candida albicans, Pichia kudriavzevii significantly exceeds the level of total antioxidant activity, and the Pichia kudriavzevii prooxidase activity was more than twice as high as in other studied micromycetes. The revealed ability of some fungi to induce oxidase stress can be considered as one of significant pathogenicity factors of microorganisms that cause pathomorphological changes in human intestinal tissues.