PTR-ToF-MS and bioprocesses: potential in monitoring VOCs release by eukaryotic microbes

The release of volatile organic compounds (VOCs) by eukaryotic microbes is of interest for several fields,comprising food, environmental, biotechnological and medical applications. In addition, it represents anintriguingly opportunity to conceive and to confirm new hypotheses in fundamental biology and in breedingsciences. For example, VOCs studies in an -omics perspective are generally defined as volatome, indicating withthis terms the organic volatile subset of metabolome. The various techniques for VOC analysis generally aim tocombine either sample throughput or analytical insight. From this point of view, Proton Transfer Reaction Timeof Flight Mass Spectrometry (PTR-ToF-MS) represents a valid compromise, with the advantages of on-lineprocess monitoring and non-invasive analysis. In order to maximize the advantages of on-line bioprocessmonitoring, we coupled PTR-ToF-MS with an auto-sampler, adding a tailored data analysis tools. Wedemonstrated the applicability of our comprehensive methodology (automatic sampling, PTR-ToF-MS analysisand tailored data handling and analysis) the study Saccharomyces cerevisiae volatile organic compoundsreleased during alcoholic fermentations. In particular, considering bread-making bioprocess, we use thisapproach i) to differentiate bakery yeast starter cultures in reason of their release of VOCs and to analyze theeffect on VOCs productivity as a function of ii) different bakery yeast starter cultures/flour combinations, ii) theinteraction between S. cerevisiae and Lactobacillus sanfranciscensis as model microorganisms in the sourdoughenvironment, iv) different commercial aromatic yeast starter cultures for bakery