Rapid Identification of Yeasts in Foods Based on Thermal-Scanning Fluorescence Spectroscopy

Here, for the first time, we propose a thermal-scanning fluorescence spectroscopy (TSFS) method for the rapid identification of yeast. In the method, SYBR Green I (a dsDNA-specific nucleic acid dye) was used as the fluorescence probe to trace physiological changes in yeast cells induced by temperature variations. Upon temperature elevation, the yeast cells exhibited a biphasic thermal response: Phase I was marked by a progressive membrane permeability increase, concomitant with gradual cell death and a corresponding rise in fluorescence intensity. Phase II involved genomic dsDNA denaturation, accompanied by a gradual decline in the fluorescence intensity. Due to species-specific differential responses to thermal stress, TSFS with taxonomic specificity can be generated. Eight types of yeasts were mixed in milk and used as models to verify the reliability of the TSFS method for food yeast composition analysis, and they could be clearly differentiated from each other through multivariate statistical analysis of the TSFS. The identification could be completed within 1 h without the need for antibodies or gene sequencing. Hence, TSFS provides a fast, simple, and low-cost solution for yeast identification and has broad application prospects in areas such as food microbiological testing, clinical pathogen screening, and environmental fungal monitoring.