Streptococcus thermophilus is a major component of dairy starter cultures used for the manufacture of yoghurt and cheese. In this study, the CO(2) metabolism of S. thermophilus DSM 20617(T), grown in either a N(2) atmosphere or an enriched CO(2) atmosphere, was analysed using both genetic and proteomic approaches. Growth experiments performed in a chemically defined medium revealed that CO(2) depletion resulted in bacterial arginine, aspartate and uracil auxotrophy. Moreover, CO(2) 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 CO(2) availability. In agreement with proteomic data, cells grown under N(2) showed a significantly higher milk acidification rate compared with those grown in an enriched CO(2) 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 CO(2) 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 CO(2) in S. thermophilus physiology, and suggesting potential applications in dairy fermentation processes.

The Relevance of Carbon Dioxide Metabolism in Streptococcus thermophilus / S. Arioli, P. Roncada, A.M. Salzano, F. Deriu, S. Corona, S.D. Guglielmetti, L. Bonizzi, A. Scaloni, D. Mora. - In: MICROBIOLOGY. - ISSN 1350-0872. - 155:6(2009), pp. 1953-1965.

The Relevance of Carbon Dioxide Metabolism in Streptococcus thermophilus

S. Arioli
Primo
;
S.D. Guglielmetti;L. Bonizzi;D. Mora
Ultimo
2009

Abstract

Streptococcus thermophilus is a major component of dairy starter cultures used for the manufacture of yoghurt and cheese. In this study, the CO(2) metabolism of S. thermophilus DSM 20617(T), grown in either a N(2) atmosphere or an enriched CO(2) atmosphere, was analysed using both genetic and proteomic approaches. Growth experiments performed in a chemically defined medium revealed that CO(2) depletion resulted in bacterial arginine, aspartate and uracil auxotrophy. Moreover, CO(2) 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 CO(2) availability. In agreement with proteomic data, cells grown under N(2) showed a significantly higher milk acidification rate compared with those grown in an enriched CO(2) 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 CO(2) 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 CO(2) in S. thermophilus physiology, and suggesting potential applications in dairy fermentation processes.
Settore VET/05 - Malattie Infettive degli Animali Domestici
Settore AGR/16 - Microbiologia Agraria
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/50754
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