In Vitro Study of Autofluorescence Dynamics in Selected Fungal Strains Under 405 nm Laser Excitation

Autofluorescence of microorganisms has emerged as a potential tool in diagnostics. However, the temporal behaviour of fungal autofluorescence and its objective quantitative evaluation remain insufficiently characterised. The present in vitro study investigated the temporal dynamics of autofluorescence in 16 reference fungal strains under 405 nm laser excitation, with a particular focus on quantitative colour analysis. Standardised fungal suspensions were cultured on Sabouraud dextrose agar and imaged after 24–168 h of incubation. Fluorescence images were acquired during excitation with a 405 nm diode laser. The images were analysed in ImageJ using the HSV colour model, with the mean hue value of the colony used as the primary quantitative parameter. Multifactorial ANOVA demonstrated significant effects of fungal strain and strain × time interaction on hue values (p < 0.001), whereas time alone was not significant. Most strains exhibited a progressive decrease in mean hue during cultivation, although strain-specific temporal patterns were observed. Blastoschizomyces capitatus maintained a stable high mean hue throughout the observation, while Candida guilliermondii showed a marked increase after 168 h. These findings underline the strain- and time-dependent nature of fungal autofluorescence and the importance of standardised imaging conditions not only for its potential diagnostic application but also for its use as an experimental tool in studies of fungal metabolism or stress responses.