Physiology of Streptococcus thermophilus during the late stage of milk fermentation with special regard to sulfur amino-acid metabolism.
Streptococcus thermophilus is a thermophilic lactic acid bacterium widely used as starter in the manufacture of dairy products in particular in yoghurt manufacture in combination with Lactobacillus delbrueckii ssp. bulgaricus. However, in spite of its massive use, the physiological state of S. thermophilus in milk has hardly been investigated. We established the first map of the cytosolic proteome of S. thermophilus LMG18311 grown in milk. It comprises 203 identified proteins corresponding to 32% of theoretical proteome. In addition, using proteomic and transcriptomic approaches, we analyzed the physiology of LMG18311 during its late stage of growth in milk (between 2h30 and 5h30). It revealed the up-regulation of (i) peptides and AA transporters and of specific AA biosynthetic pathways notably for sulfur AA and (ii) genes and proteins involved in the metabolism of various sugars. These two effects were also observed in LMG18311 grown in milk in coculture with L. bulgaricus although the effect on sugar metabolism was less pronounced. It suggests that the stimulatory effect of Lactobacillus on the Streptococcus growth is more complex than AA or peptides supply.
Herve-Jimenez
Luciana
L
INRA,UR477 Biochimie Bactérienne, Jouy-en-Josas, France.
Guillouard
Isabelle
I
Guedon
Eric
E
Gautier
Céline
C
Boudebbouze
Samira
S
Hols
Pascal
P
Monnet
Véronique
V
Rul
Françoise
F
Maguin
Emmanuelle
E
D000603:Amino Acids, Sulfur / Q000378:metabolism*; D000818:Animals; D001426:Bacterial Proteins; D018920:Coculture Techniques; D005285:Fermentation / Q000502:physiology*; D005798:Genes, Bacterial / Q000502:physiology; D048668:Lactobacillus delbrueckii / Q000254:growth & development; D008892:Milk / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D020543:Proteome / Q000378:metabolism; D048249:Streptococcus thermophilus / Q000254:growth & development / Q000502:physiology*; D015854:Up-Regulation
D000603:Amino Acids, Sulfur; D001426:Bacterial Proteins; D020543:Proteome; D009584:Nitrogen