Identification of stress-inducible proteins in Lactobacillus delbrueckii subsp. bulgaricus

Electrophoresis. 2000 Jul;21(12):2557-61. doi: 10.1002/1522-2683(20000701)21:12<2557::AID-ELPS2557>3.0.CO;2-B.


Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) is a homofermentative bacterium that produces lactic acid during growth. We adapted the two-dimensional electrophoresis (2-DE) technique to study the response of this bacterium to acidity. De novo protein synthesis was monitored by [35S]methionine labeling of exponentially growing cultures under standard (pH 6) and acidic (pH 4.75) conditions. After 2-DE separation, the protein patterns were compared. The protein spots showing increased radioactivity levels under acid conditions were considered acid-induced. We determined the N-terminal amino acid sequence of three highly induced proteins; comparing these proteins to databases we identified them to be the well-known heat shock proteins GroES, GroEL, and DnaK. Their induction levels were measured and compared. This is the first study by 2-DE of stress response in L. bulgaricus. We established the method and present a protein map which will be useful for future studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acids
  • Bacterial Proteins / analysis*
  • Chaperonin 10 / analysis*
  • Chaperonin 60 / analysis*
  • Electrophoresis, Gel, Two-Dimensional / methods
  • Escherichia coli Proteins*
  • HSP70 Heat-Shock Proteins / analysis*
  • Lactobacillus / chemistry*


  • Acids
  • Bacterial Proteins
  • Chaperonin 10
  • Chaperonin 60
  • Escherichia coli Proteins
  • HSP70 Heat-Shock Proteins
  • dnaK protein, E coli