Bhi medium

Two different culture media were used: (1) Supplemented Brain Heart Infusion (BHI) medium: BHI medium (VWR, Avantor, PA, USA), 2% (w/v) gelatin (Sigma-Aldrich, Hamburg, Germany), 1% (w/v) yeast extract (VWR, Avantor, PA, USA), and 0.1% (w/v) soluble starch (Merck, Gernsheim, Germany); (2) New York City III (NYCIII) medium: 0.4% (w/v) HEPES buffer (Merck, Gernsheim, Germany), 1.5% (w/v) proteose peptone (VWR, Avantor, PA, USA), 0.5% (w/v) sodium chloride (VWR, Avantor, PA, USA), 0.5% (w/v) glucose (VWR, Avantor, PA, USA), 2.5% (w/v) yeast extract (VWR, Avantor, PA, USA), and 10% (v/v) fetal bovine serum (FBS) (Sigma-Aldrich, Hamburg, Germany). The incubation conditions used were as follows: 24 h, 10% CO₂, and 37 °C (Binder GmbH, Tuttlingen, Germany).

Thirty B. thermosphacta strains were used (Table 1), mainly selected from our laboratory collection (INRAE-Secalim, Paris, France), IFREMER Nantes B. thermosphacta collection, and two were selected from the DSMZ-German Collection of Microorganisms and Cell Cultures (DSMZ 20171T and 20599). The main selection criterion was the diversity of environmental sources (food matrices or abiotic surfaces). B. thermosphacta strains were grown at 25 °C in brain heart infusion (BHI) medium (VWR chemicals, France) from a working stock prepared in BHI broth with 20% glycerol (VWR chemicals, France), and then stored at −80 °C. The bacteria were subcultured on BHI-agar plates at 25 °C for 24 h before use.