FIG. 1.

Proteomic analyses of cytosolic proteins of L. lactis MG1363 under respiration versus aeration growth. Protein extracts (250 μg of protein per sample) of late-log-phase cultures (see Materials and Methods) were analyzed by two-dimensional gel electrophoresis (pH gradient 4 to 7). Gels were stained with colloidal Coomassie blue. (A) Profile of aerated culture extract (OD₆₀₀ = 1.6). Note that aeration and fermentation culture extract profiles were indistinguishable (data not shown). Fine arrows indicate protein spots whose intensities were reproducibly and significantly different under the two conditions (see Table 2). (B) Profile of respiration culture extract (OD₆₀₀ = 3.5). Black arrows show spots whose amounts are decreased in respiration growth; white arrows show spots whose amounts are increased in respiration growth. a and b correspond to posttranslational protein events. X and Y both correspond to RpoA protein, as does the larger adjacent spot to their upper right; however, protein levels were not reproducibly different. Gels were repeated at least four times for each condition, with two independently prepared samples.