microbiology, Vol 143, 1587-1594, Copyright © 1997 by Society for General Microbiology

ARTICLES

A 16 kDa protein family overexpressed by Streptococcus thermophilus PB18 in acid environments

H Gonzalez-Marquez, C Perrin, P Bracquart, C Guimont and G Linden
Laboratoire des Biosciences de l'Aliment, Unite Associee a l'INRA, Universite Henri Poincare, Vandoeuvre-les-Nancy, France.

The one- and two-dimensional protein patterns of Streptococcus thermophilus PB18 in the exponential and stationary phases of growth were analysed. One-dimensional SDS-PAGE showed that a 16 kDa protein was overexpressed in stationary phase as well as 2 h after an acid shock, and that it was not expressed when the bacteria reached the stationary phase in medium with limiting lactose concentrations (5 or 10 g l-1), in which the pH (5.5) was not as acid as in control cultures (pH 4.7, lactose 20 g l-1). The results support the idea that this protein is expressed in response to the acidic environment and not in response to the growth phase. Two-dimensional PAGE showed that nine proteins were expressed only during the exponential phase and ten others only during the stationary phase. The 16 kDa band seen in one- dimensional SDS-PAGE corresponded to a 16 kDa protein family observed on two-dimensional SDS-PAGE/IEF gels, whose expression was increased 8.5-fold when the extracellular pH reached a critical value below 5.0. The N-terminal sequences of proteins from two spots on the two- dimensional gels (members of the 16 kDa family) were determined and found to be identical. The physiological role of this protein family has not yet been elucidated.

This article has been cited by other articles:

				M. Varcamonti, M. R. Graziano, R. Pezzopane, G. Naclerio, S. Arsenijevic, and M. De Felice Impaired Temperature Stress Response of a Streptococcus thermophilus deoD Mutant Appl. Envir. Microbiol., February 1, 2003; 69(2): 1287 - 1289. [Abstract] [Full Text] [PDF]

				J. A. Wouters, F. M. Rombouts, W. M. de Vos, O. P. Kuipers, and T. Abee Cold Shock Proteins and Low-Temperature Response of Streptococcus thermophilus CNRZ302 Appl. Envir. Microbiol., October 1, 1999; 65(10): 4436 - 4442. [Abstract] [Full Text]