Silver-stained 2-DE gels images of Lactobacillus sakei strain 23K grown in a completely defined medium supplemented with glucose (a) or ribose (b), and the lower part of a 2-DE gel image from L. sakei strain MF1053 grown on glucose (c). Protein (50 μg) was loaded, and 2-DE was performed using a pH range of 4-7 in the first dimension and SDS-PAGE (12.5%) in the second dimension. Protein size (kDa) is shown on the right side of each gel image. Spots listed in Additional files 1 and 2, Tables S2 and S3 are indicated. The black rectangle (a) shows the region of the GapA isoforms which differ among the strains.