ENRICHMENT OF THE OENOLOGICAL MALDI-TOF/MS PROTEIN SPECTRA DATABASE FOR RELIABLE OENOLOGICAL YEAST AND BACTERIA IDENTIFICATION

Abstract

The Matrix Assisted Laser Desorption/Ionization–Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) technology is commonly used in food and medical sector to identify yeast or bacteria species isolated from a nutritive culture media. Since a decade, brewery and oenology industries have been attracted to this method which combines fast analysis times, reliability and low cost of analysis. Briefly, this method is based on the comparison of the MALDI-TOF/MS protein spectra of an isolated colony of yeast or bacteria with those contain in a manufacturer’s reference protein spectra database. Initiated in 2015, the creation of the first oenological mass spectra database has proved to be essential for increase quality of species identification. Indeed some yeast or bacteria of interest in oenological environment are less representative or absent from manufacturer’s reference spectra database such as some species of Pichia or Starmerella genus for yeast and Acetobacter species for bacteria. Moreover, many study demonstrated that yeast and bacteria isolated from wine related environment have some particular genetic and phenotypic characteristics and commonly belong to separated subgroups within the species. These wine strains specificity make essential to create an oenological dedicated MALDI-TOF/MS spectra database with wine related environment isolated yeast and bacteria strains to obtain successful identification by MALDI-TOF/MS. The oenological mass spectra database contains today more than 200 yeast and bacteria species, corresponding to 40 different oenological yeast species and 28 distinct species of acetic and lactic acid bacteria, mainly provide by the Biological Resources Centre CRBO (ISVV). The database has been implemented and successfully used in several studies related to yeast and bacteria species diversity analysis as well as the impact on the winemaking process (pre-fermentery stages without SO₂, use of chitosan).

This oenological mass spectra database is extensible and constantly implemented to meet the needs or future challenges of the wine industry. Finally, this innovative method of MALDI-TOF/MS, completed with oenological mass spectra database, allows quick and cheap implantation validation of grape juice bioprotection preparation composed of oenological yeast species.