Fluorescence spectrum photo-bleaching analysis for distinguishing microorganisms (bacteria and fungi) from other particles in air

A new device with a 405 nm blue laser diode is developed for collecting samples in air and detecting their spectra variation. The multi-sample particles which are pure microorganisms can be distinguished from interferents in the air by photo-bleaching phenomenon. Six types of microorganisms and twelve types of interferents from the air, which exhibit laser-induced fluorescence, are used to evaluate the performance of the analysis approach, and their fluorescence emission spectra are presented. The results show that when microorganisms are illuminated by the laser, the fluorescence spectra will change significantly within several minutes, including both the wavelength of the main peak and fluorescence intensity. Our work provides a potential approach to distinguish microorganisms from other particles by the changes.