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Post-genomic analysis of Streptococcus thermophilus and Lactobacillus delbruekii ssp. bulgaricus cooperative growth in milk

Abstract : Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus are thermophilic lactic acid bacteria used for the manufacture of yoghurt. In milk, the association of these two species can have positive effect on their growth and on the acidification rate, it is therefore considered as protocooperation. Although the basis of this cooperation remains poorly characterised, previous studies showed that nutritional exchanges are implicated. The recent completion of the genome sequences of both S. thermophilus and L. bulgaricus allows re-examining this phenomenon at a molecular level using genomic and post-genomic analysis. Our objective is to unravel the molecular basis of the protocooperation, to evaluate the nature and the extent of the exchanges between the two species and to determine if other phenomena such as inter-species regulation occur. We selected a couple of strains which co-culture resulted in a marked improvement on S. thermophilus growth, higher acidification rate and lower post-acidification values. Using proteomic and transcriptomic analysis, the pure cultures and the co-culture in milk have been compared at two different growth stages (early and late exponential). 88 genes or proteins (4.6% of CDS) of S. thermophilus were modified in presence of L. bulgaricus. Of note, amino acids biosynthesis, purines biosynthesis and iron transport and chelating were modified. Proteomic and transcriptomic data will be integrated in order to give an interpretation of metabolic modifications observed when two lactic acid bacteria interact in an ecosystem.
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https://pastel.archives-ouvertes.fr/pastel-00004080
Contributor : Ecole Agroparistech <>
Submitted on : Thursday, February 12, 2009 - 8:00:00 AM
Last modification on : Thursday, February 12, 2009 - 8:00:00 AM
Long-term archiving on: : Thursday, June 30, 2011 - 1:18:11 PM

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Luciana Hervé-Jiménez. Post-genomic analysis of Streptococcus thermophilus and Lactobacillus delbruekii ssp. bulgaricus cooperative growth in milk. Life Sciences [q-bio]. AgroParisTech, 2008. English. ⟨NNT : 2008AGPT0034⟩. ⟨pastel-00004080⟩

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