Previous Article | Next Article ![]()
Applied and Environmental Microbiology, June 2007, p. 3924-3935, Vol. 73, No. 12
0099-2240/07/$08.00+0 doi:10.1128/AEM.01502-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
,
Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, SE-750 07 Uppsala, Sweden,1 Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824,2 Department of Pathology, Baylor College of Medicine and Texas Children's Hospital, 6621 Fannin St., MC 1-2261, Houston, Texas 770303
Received 29 June 2006/ Accepted 16 April 2007
To be able to function as a probiotic, bacteria have to survive the passage through the gastrointestinal tract. We have examined survival and gene expression of Lactobacillus reuteri ATCC 55730 after a sudden shift in environmental acidity to a pH close to the conditions in the human stomach. More than 80% of the L. reuteri cells survived at pH 2.7 for 1 h. A genomewide expression analysis experiment using microarrays displayed 72 differentially expressed genes at this pH. The early response to severe acid shock in L. reuteri differed from long-term acid adaptation to milder acid stress studied in other lactic acid bacteria. The genes induced included the following: clpL, genes putatively involved in alterations of the cell membrane and the cell wall; genes encoding transcriptional regulators; phage genes; and genes of unknown function. Two genes, clpL, encoding an ATPase with chaperone activity, and lr1516, encoding a putative esterase, were selected for mutation analyses. The mutants were significantly more sensitive to acid than the wild type was. Thus, these genes could contribute to the survival of L. reuteri in the gastrointestinal tract.
Published ahead of print on 20 April 2007.
Supplemental material for this article may be found at http://aem.asm.org/.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»