Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 334004
Title Sugar utilisation and conservation of the gal-lac gene cluster in Streptococcus thermophilus
Author(s) Bogaard, P.T.C. van den; Hols, P.; Kuipers, O.P.; Kleerebezem, M.; Vos, W.M. de
Source Systematic and Applied Microbiology 27 (2004)1. - ISSN 0723-2020 - p. 10 - 17.
Department(s) Microbiology
Publication type Refereed Article in a scientific journal
Publication year 2004
Keyword(s) lactose transport-system - 16s ribosomal-rna - beta-galactosidase - exopolysaccharide production - phosphotransferase systems - escherichia-coli - acid bacteria - phosphoenolpyruvate - expression - transcription
Abstract The adaptation to utilise lactose as primary carbon and energy source is a characteristic for Streptococcus thermophilus. These organisms, however only utilise the glucose moiety of lactose while the galactose moiety is excreted into the growth medium. In this study we evaluated the diversity of sugar utilisation and the conservation of the gal-lac gene cluster in a collection of 18 S. thermophilus strains isolated from a variety of sources. For this purpose analysis was performed on DNA from these isolates and the results were compared with those obtained with a strain from which the complete genome sequence has been determined. The sequence, organisation and flanking regions of the S. thermophilus gal-lac gene cluster were found to be highly conserved among all strains. The vast majority of the S. thermophilus strains were able to utilize only glucose, lactose, and sucrose as carbon sources, some strains could also utilize fructose and two of these were able to grow on galactose. Molecular characterisation of these naturally occurring Gal+ strains revealed up-mutations in the galKTE promoter that were absent in all other strains. These data support the hypothesis that the loss of the ability to ferment galactose can be attributed to the low activity of the galKTE promoter, probably as a consequence of the adaptation to milk in which the lactose levels are in excess.
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