The proto-cooperation between Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus in the yogurt consortium enhances the growth rate and size of each population. In contrast, the independent growth of the two species in milk leads to a slower growth rate and a smaller population size. In this study, we report the first evidence that the urease activity of S. thermophilus increases the intracellular pH of L. delbrueckii in the absence of carbon source. However, in milk, in the presence of lactose the alkalizing effect of urea-derived ammonia was not detectable. Nevertheless, based on glucose consumption and lactic acid production at different pHin, L. delbrueckii showed an optimum of glycolysis and homolactic fermentation at alkaline pH values. In milk, we observed that ammonia provided by urea hydrolysis boosted lactic acid production in S. thermophilus and in L. delbrueckii when the species were grown alone or in combination. Therefore, we propose that urease activity acts as an altruistic cooperative trait, which is costly for urease-positive individuals but provides a local benefit because other individuals can take advantage of urease-dependent ammonia release.

Arioli, S., Della Scala, G., Remagni, M., Stuknyte, M., Colombo, S., Guglielmetti, S., et al. (2017). Streptococcus thermophilus urease activity boosts Lactobacillus delbrueckii subsp. bulgaricus homolactic fermentation. INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY, 247, 55-64 [10.1016/j.ijfoodmicro.2016.01.006].

Streptococcus thermophilus urease activity boosts Lactobacillus delbrueckii subsp. bulgaricus homolactic fermentation

Guglielmetti S.;
2017

Abstract

The proto-cooperation between Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus in the yogurt consortium enhances the growth rate and size of each population. In contrast, the independent growth of the two species in milk leads to a slower growth rate and a smaller population size. In this study, we report the first evidence that the urease activity of S. thermophilus increases the intracellular pH of L. delbrueckii in the absence of carbon source. However, in milk, in the presence of lactose the alkalizing effect of urea-derived ammonia was not detectable. Nevertheless, based on glucose consumption and lactic acid production at different pHin, L. delbrueckii showed an optimum of glycolysis and homolactic fermentation at alkaline pH values. In milk, we observed that ammonia provided by urea hydrolysis boosted lactic acid production in S. thermophilus and in L. delbrueckii when the species were grown alone or in combination. Therefore, we propose that urease activity acts as an altruistic cooperative trait, which is costly for urease-positive individuals but provides a local benefit because other individuals can take advantage of urease-dependent ammonia release.
Articolo in rivista - Articolo scientifico
Lactic-acid bacteria; food fermentations; intracellular PH; flow-cytometry; metabolism; milk; strains; yogurt; growth; microorganisms
English
2017
247
55
64
reserved
Arioli, S., Della Scala, G., Remagni, M., Stuknyte, M., Colombo, S., Guglielmetti, S., et al. (2017). Streptococcus thermophilus urease activity boosts Lactobacillus delbrueckii subsp. bulgaricus homolactic fermentation. INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY, 247, 55-64 [10.1016/j.ijfoodmicro.2016.01.006].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/452881
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