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    Novel Streptococcus infantarius subsp. infantarius variants harboring lactose metabolism genes homologous to Streptococcus thermophilus

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    Date
    2012-08
    Author
    Jans, Christoph
    Gerber, Andrea
    Bugnard, Josephine
    Njage, Patrick Murigu Kamau
    Lacroix, Christophe
    Meile, Leo
    Type
    Article
    Language
    en
    Metadata
    Show full item record

    Abstract
    Streptococcus infantarius subsp. infantarius belongs to the Streptococcus bovis/Streptococcus equinus complex (SBSEC) commonly associated with human and animal infections. We elucidated the lactose metabolism of S. infantarius subsp. infantarius predominant in African fermented milk products. S. infantarius subsp. infantarius isolates (n = 192) were identified in 88% of spontaneously fermented camel milk suusac samples (n = 24) from Kenya and Somalia at log10 8.2–8.5 CFU mL−1. African S. infantarius isolates excreted stoichiometric amounts of galactose when grown on lactose, exhibiting a metabolism similar to Streptococcusthermophilus and distinct from their type strain. African S. infantarius subsp. infantarius CJ18 harbors a regular gal operon with 99.7–100% sequence identity to S. infantarius subsp. infantarius ATCC BAA-102T and a gal-lac operon with 91.7–97.6% sequence identity to S. thermophilus, absent in all sequenced SBSEC strains analyzed. The expression and functionality of lacZ was demonstrated in a β-galactosidase assay. The gal-lac operon was identified in 100% of investigated S. infantarius isolates (n = 46) from suusac samples and confirmed in Malian fermented cow milk isolates. The African S. infantarius variant potentially evolved through horizontal gene transfer of an S. thermophilus-homologous lactose pathway. Safety assessments are needed to identify any putative health risks of this novel S. infantarius variant.
    URI
    http://www.sciencedirect.com/science/article/pii/S0740002012000275
    http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/39876
    Citation
    Jans, C et al(2012). Novel Streptococcus infantarius subsp. infantarius variants harboring lactose metabolism genes homologous to Streptococcus thermophilus. Food Microbiology; 31(1): 33-42
    Publisher
    Department of Food Science, Nutrition and Technology, University of Nairobi
    Subject
    Fermented camel milk
    Galactose-lactose metabolism
    Gal-lac operon
    Streptococcus infantarius
    Streptococcus bovis
    Horizontal gene transfer
    Description
    Journal article
    Collections
    • Faculty of Agriculture & Veterinary Medicine (FAg / FVM) [5481]

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