Fig. 1.

a Acetate and propionate production by Lactobacillus rhamnosus GG and L. gasseri PA 16/8, Bifidobacterium longum SP 07/3 and B. bifidum MF 20/5in supernatant (white bars), cellular extracts (stripped bars) and total production (black bars). The bacterial strains have been grown overnight in MRS medium (plus cysteine for bifidobacteria strains) at 37 °C. Cultures were then centrifuged (5000g for 10 mn at 4 °C). Supernatants and pellets were separated and frozen in liquid nitrogen immediately. The error bars are SEM (Standard Error Mean) and the experiments were performed four times. They were kept at −80 °C until further analyses. Acetate, butyrate and propionate were quantified in supernatant and pellets by Mass Spectromectry. b B group vitamin production by L. rhamnosus GG in supernatant (white bars), cellular extracts (stripped bars) and total production (black bars). The probiotic strain was grown in folate, riboflavin or thiamin free media (Difco) after which cells were centrifuged (4000×g) and washed with saline solution (0.85% NaCl, m/v). Folates and riboflavin were quantified according to previously described microbiological methods [41, 88] and thiamin using a Xevo Triple-Quadrupole mass spectrometer (Waters Corporation) equipped with an electrospray ionization interface coupled to an Acquity H-Class UPLCTM device (Waters Corporation) according to Waters application notes LGC/R/2011/181