The relevance of carbon dioxide metabolism in Streptococcus thermophilus

Stefania Arioli, Paola Roncada, Anna Maria Salzano, Francesca Deriu, Silvia Corona, Simone Guglielmetti, Luigi Bonizzi, Andrea Scaloni, Diego Mora

Research output: Contribution to journalArticlepeer-review

Abstract

Streptococcus thermophilus is a major component of dairy starter cultures used for the manufacture of yoghurt and cheese. In this study, the CO2 metabolism of S. thermophilus DSM 20617T, grown in either a N2 atmosphere or an enriched CO2 atmosphere, was analysed using both genetic and proteomic approaches. Growth experiments performed in a chemically defined medium revealed that CO2 depletion resulted in bacterial arginine, aspartate and uracil auxotrophy. Moreover, CO2 depletion governed a significant change in cell morphology, and a high reduction in biomass production. A comparative proteomic analysis revealed that cells of S. thermophilus showed a different degree of energy status depending on the CO2 availability. In agreement with proteomic data, cells grown under N2 showed a significantly higher milk acidification rate compared with those grown in an enriched CO2 atmosphere. Experiments carried out on S. thermophilus wild-type and its derivative mutant, which was inactivated in the phosphoenolpyruvate carboxylase and carbamoyl-phosphate synthase activities responsible for fixing CO2 to organic molecules, suggested that the anaplerotic reactions governed by these enzymes have a central role in bacterial metabolism. Our results reveal the capnophilic nature of this micro-organism, underlining the essential role of CO2 in S. thermophilus physiology, and suggesting potential applications in dairy fermentation processes.

Original languageEnglish
Pages (from-to)1953-1965
Number of pages13
JournalMicrobiology
Volume155
Issue number6
DOIs
Publication statusPublished - 2009

ASJC Scopus subject areas

  • Microbiology

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