Fig 1.
Growth and survival of P. freudenreichii subsp. shermani CIRM BIA 1 in EJ and CdM
(A) growth curve and (B) Live/dead staining of the bacterial cells in the exponential (Exp), early stationary (E.Stat) and late stationary phase (L.Stat) of growth in CdM (black dot) and in EJ (white dot).
Fig 2.
Degradation and production of various organic acids during growth of P. freudenreichii subsp. shermani CIRM BIA 1 in (A) CdM and (B) EJ.
blue square lactic acid; white and green triangle acetic acid, green triangle propionic acid and purple square citric acid. The arrows indicate the main growth stages corresponding to each incubation medium: exponential (Exp), early stationary (E.Stat) and late stationary phase (L.Stat). Lactate was almost entirely consumed in both media with less than 3% left at the end of culture time. The plateau in CdM was observed in late stationary phase (98% lactate degradation). In the case of EJ, citrate was present concomitantly with lactate and used by P. freudenreichii subsp. shermani CIRM BIA 1 as a carbon source after lactate was exhausted i.e., at early stationary phase.
Fig 3.
Relative change in free amino acid concentration during growth of P. freudenreichii subsp. shermani CIRM BIA 1 in CdM (A, C and E) and EJ (B, D and F).
(A and B) Alliphatic amino acids; (C and D) basic, acidic + amide amino acids; (E and F) Aromatic, hydroxyl and sulfur-containing amino acids. The arrows indicate the main growth phases corresponding to each incubation medium: exponential (Exp), early stationary (E.Stat) and late stationary phase (L.Stat).
Table 1.
Initial composition in free amino acids of the EJ and the CdM.
Fig 4.
Two-dimensional analysis of protein expression during growth of P. freudenreichii subsp. shermani CIRM BIA 1 in EJ and in CdM.
(A) Neosynthesized proteins were radiolabeled with 35S amino acids in both media during indicated duration: lag phase (early), the beginning of the exponential phase (early exponential), the exponential and early stationary phases. (B) Cellular proteins accumulated during growth were Coomassie blue stained.
Table 2.
Proteins differentially expressed after growth of P. freudenreichii subsp. shermani CIRM BIA 1 in EJ and in CdM and identified by on line coupling NanoLC-ESI-Q-TOF tandem mass spectrometry.
Fig 5.
P. freudenreichii subsp. shermani CIRM BIA 1 tolerance to digestive stresses.
Propionibacteria were harvested at different stages of growth in CdM black square or in EJ white square, prior to acid (A, pH 2) or bile salts (B, 1 g L-1) challenges. Surviving bacteria were then counted by CFU enumeration. Means with different lower case superscript letters (a-b) differ significantly (P < 0.05) in italic groups for CdM and in normal case groups for EJ.