Bifidobacterium adolescentis Strains Characterization

Two B. adolescentis strains were used in this work. The strain B. adolescentis IPLA60004, from here onward IPLA60004, belongs to IPLA-CSIC culture collection. IPLA60004 was previously isolated from a human colonic biopsy and was demonstrated to have a high capability to convert the GABA precursor monosodium glutamate (MSG) into GABA (19 (link), 29 (link)). The strain B. adolescentis LMG10502^T, from here onward LMG10502^T, was purchased from the Belgium culture collection (BCCM/LMG Bacteria Collection, Belgium) and was previously demonstrated to lack gad genes, and hence, the capacity to produce GABA. The strains were routinely grown in MRS_c medium [MRS (Biokar, France) supplemented with 0.25% (wt/vol) L-cysteine hydrochloride monohydrate (Sigma-Merck, Germany)]. Stocks stored at −80°C were resuscitated in agar-MRS_c in anaerobic jar with anaerocult A (Merck, Germany) at 37°C for 2 days. Isolated colonies were inoculated in 50 mL of MRS_c broth and incubated under the same conditions for 20 ± 1 h to obtain the bifidobacterial cultures.