Determination by 2D-PAGE of the protein fingerprint of Streptococcus thermophilus.

2D-PAGE coupled with an image analysis system was applied to determine the basic protein bidimensional fingerprint of a Streptococcus thermophilus str ain in log phase in M17 medium and the extent of strain variation by compar ison with two other strains from different industrial origins. The basic 2D image of S. thermophilus presents about 220 spots after silver detection; their average molecular mass and isoelectric point were estimated to be 41 600 Da and 5.2 respectively. The proportion of matched spots among images o f the strains was relatively important (80 to 85%). Using the database of t his study, the protein expression of other strains of S. thermophilus grown under different environmental conditions can be compared to identify diffe rences.