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Electrophoresis. 2000 Jul;21(12):2557-61.

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

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1
Génétique Microbienne, Institut National de la Recherche Agronomique, Jouy-en-Josas, France. emlim@biotec.jouy.inra.fr

Abstract

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.

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