Serum acetaldehyde as a potential biomarker for the detection of pathogenic biofilm formation by Candida albicans

Candida albicans is a fungus that causes opportunistic infections in humans. It secretes toxic metabolites and induces the formation of biofilms. Fully developed C. albicans biofilms consist of planktonic yeast cells, pseudohyphae, and hyphae. The hyphae can invade tissues and bring toxic metabolites deep inside the organs and into the bloodstream. Biofilms cannot be identified by culture methods from feces or blood samples, necessitating the development of biomarkers to detect them. Here we show that the acetaldehyde level in serum can be used as a biomarker of gastrointestinal Candida biofilm formation. An in vitro C. albicans biofilm model is set up by culturing C. albicans in an Erlenmeyer flask, while an in vivo model is created in the rat gastrointestinal mucosa. A lack of nutrients induces biofilm formation in vitro, while in vivo biofilm formation is induced by treatment with antibiotics and corticosteroids. Identification of C. albicans biofilms is carried out macroscopically and microscopically using scanning electron microscopy. Analysis of acetaldehyde levels is performed by gas chromatography. The in vitro acetaldehyde level in the supernatant of the C. albicans culture is 0.9 ± 0.3 % (v/v) after a period of 48 h incubation, at which time biofilms start to form. The serum mean acetaldehyde level is 0.011 ± 0.003 % and 0.005 ± 0.001 % in the experimental and the control groups, respectively. The t-test results show that this difference is significant at p < 0.05, indicating that serum acetaldehyde can be used as a biomarker of C. albicans biofilm formation in the intestine.