Identifying yeasts using surface enhanced Raman spectroscopy.

The molecular fingerprints of yeasts Saccharomyces cerevisiae , Dekkera bruxellensis , and Wickerhamomyces anomalus (former name Pichia anomala) have been examined using surface-enhanced Raman spectroscopy (SERS) and helium ion microscopy (HIM). The SERS spectra obtained from cell cultures (lysate and non-treated cells) distinguish between these very closely related fungal species. Highly SERS active silver nano-particles suitable for detecting complex biomolecules were fabricated using a simple synthesis route. The yeast samples mixed with aggregated Ag nanoparticles yielded highly enhanced and reproducible Raman signal owing to the high density of the hot spots at the junctions of two or more Ag nanoparticles and enabled to differentiate the three species based on their unique features (spectral fingerprint). We also collected SERS spectra of the three yeast species in beer medium to demonstrate the potential of the method for industrial application. These findings demonstrate the great potential of SERS for detection and identification of fungi species based on the biochemical compositions, even in a chemically complex sample. Unlabelled Image • High quality, i.e. sharp, reproducible, and excellent signal to noise ratio, SERS spectra of yeast microbes ((SC (wild yeast) , DB and WA obtained • SERS detection from very closely related fungal species (lysed and non-treated) • Detection of the three species in complex beer medium • High-resolution helium ion microscope (HIM) images give insight into the surface morphology of the yeast cells attached to AgNP • SERS to be used for reliable detection and identification of the species in biosensing applications. [ABSTRACT FROM AUTHOR]