Gardnerella Strains Culturing and Maintenance

Various strains from the genus Gardnerella were analyzed in this study. Gardnerella sp. UM241, previously recovered from patients diagnosed with BV^{93 (link)}, G. vaginalis UM137, G. piotii UM035, G. leopoldii UGent 09.48, and G. swidsinskii GS 9838-1, previously identified by MALDI-TOF^{15 (link),94 (link)}, were used herein. The strains were kept frozen in Brain Heart Infusion medium (BHI, Liofilchem, Roseto degli Abruzz, Italy) with 23% (v/v) of glycerol (Panreac, Barcelona, Spain) and plated in Columbia Blood Agar (CBA) [Columbia Base Agar medium (Liofilchem) supplemented with 5% (v/v) of defibrinated horse blood (Oxoid Ltd, Hampshire, UK)] and incubated for 48 h at 37 °C and 10% CO₂. For each experiment, planktonic cells were grown in BHI supplemented (sBHI) with 2% (w/v) gelatin (Liofilchem), 0.1% (w/v) starch (Panreac) and 0.5% (w/v) yeast extract (Liofilchem) and incubated for 24 h at 37 °C and 10% CO₂ (CO₂ Incubator MCO-18AC, Panasonic, Bracknell, UK).