Updated project metadata. Xanthan is the most used polysaccharide of bacterial origin. There are many industrial applications for xanthan, especially in food products. The organism Xanthomonas campestris is commonly used for xanthan fermentation, but little is known about the xanthan synthesis mechanism on the proteome level. The study used a label-free LC-MS/MS method to investigate the protein shifts during a typical xanthan fermentation of 72 hours. Two thousand four hundred sixteen proteins were identified, representing 54.75 % of the 4413 entries in the reference database. One thousand seven hundred forty-nine proteins were measured in a quantifiable quality. The quality of the proteome data was examined by the abundance changes of the ribosomal proteins according to the growth phases. The phenotypic changes during the cultivation, especially processes known to be influencing or close related to xanthan production, were investigated by proteome analysis. These processes were nitrogen metabolism, sugar nucleotide metabolism, and xanthan synthesis. This study shows the abundance of changes in central metabolites during a xanthan fermentation of Xcc. The presented research provides crucial information for further biotechnological studies to improve xanthan production.