Cacl2.2h2o

Deionized water filtered using a Milli Q system (Millipore, France) was used for the media and Se solution preparation. Cultures were performed in 250-mL Erlenmeyer flasks containing 50 mL of a medium having the following composition (in g/L): glucose, 70.0 (AppliChem, Darmstadt, Germany); Na₂HPO₄, 12.0 (AppliChem); KH₂PO₄, 12.0 (AppliChem); yeast extract, 3.0 (Conda, Madrid, Spain); FeCl_3.6H₂O, 0.1 (AnalaR NORMAPUR®, Poole, England); CaCl₂.2H₂O, 0.1 (Carlo Erba, Rodano, Italy); ZnSO₄.7H₂O, 0.001 (Merck, Darmstadt, Germany); CuSO₄.5H₂O, 0.0001 (AnalaR NORMAPUR®); Co(NO₃)_3.3H₂O, 0.0001 (Merck); and MnSO₄.5H₂O, 0.0001 (Fluka, Steinheim, Germany). In some cases, the media were supplemented with sterile Na₂SeO₃ solution (1000 mg Se⁴⁺/L; Sigma-Aldrich, Warsaw, Poland) in order to reach a final Se concentration of 10 mg/L. The media and aqueous Na₂SeO₃ salt solutions were sterilized at 121 °C for 20 min. The medium pH after sterilization was 6.0 ± 0.3 and remained almost unchanged during cultivations, due to its high buffer capacity [39 (link)].
After sterilization, the cultures were inoculated with 1 mL of a 48-h pre-culture (3.0–4.0 × 10⁵ cfu/mL) carried out on potato dextrose broth (Himedia), and incubated on a shaker (ZHWY 211C, Zhicheng, Shanghai, China) under a vibration amplitude of 180 rpm for 96 h at + 28 °C.

Glucose, K₂HPO₄, NaH₂PO₄, CaCl₂.2H₂O, HCl, and pure glycerol (Carlo Erba Reagents, Val-de-Reuil, France). Peptone (PanReac AppliChem, Barcelona, Spain). Yeast extract and agar (Oxoid, Basingstoke, UK). MgSO₄.7H₂O (J.T. Baker, PA, USA). KH₂PO₄ (Macron Chemicals, PA, USA). Tetramethyl orthosilicate (TMOS) (Merck, Darmstadt, Germany). Agarose (Bioron, Römerberg, Germany). Alginate (Sigma, Burlington, VT, USA). Montmorillonite (MT) (Aldrich, Burlington, VT, USA).