Yeast extract

Two concentrations of lactose and potassium nitrate were tested for a pool of strains in preliminary tests.
lactose fermentation was tested in a modified API 50CH medium containing the following: lactose 5 or 20 g.L⁻¹ (Panreac, Lyon, France), tryptone 10 g.L⁻¹, yeast extract 5 g.L⁻¹, K₂HPO₄, 0.25 g.L⁻¹, MnSO₄ 0.05 g.L⁻¹, and bromocresol purple 0.17 g.L⁻¹. The medium was inoculated using 1% (v/v) of 48-h cultures in YEL, and incubated at 30 °C under anaerobiosis (using the Anaerocult A system, Merck, Darmstadt, Germany). The production of acid from lactose was determined from the colour change of bromocresol purple from purple to yellow after 2, 5, and 7 days of incubation.
Nitrate reductase activity was detected by means of the Griess reagent (Biomérieux, Marcy l'Etoile, France) after incubation of cultures at 30 °C under microaerophilic conditions (air atmosphere without agitation) in a broth containing potassium nitrate, 0.5 or 1.5 g.L⁻¹ (VWR International, Fontenay-sous-Bois, France), tryptone (Biokar Diagnostics, Allone, France) 10 g.L⁻¹, yeast extract (Biokar Diagnostics) 5 g.L⁻¹, and glucose (Grosseron, Saint-Herblain, France) 1 g.L⁻¹, according to Dalmasso et al. (2011 (link)). The results of the tests were read after 2 and 5 days of incubation.
All the tests were carried out in triplicate.

C. albicans YP0037, C. glabrata YP0937, C. parapsilosis YP0515, Candida krusei YP0338, T. rubrum IMF028, T. mentagrophytes IMF029, Aspergillus niger IMF005, Fusarium oxysporum IMF033, and Alternaria alternata IMF030 were obtained from the Clinical Yeast Collection—University of Coimbra (CYCUC) of the Institute of Microbiology of the Faculty of Medicine of the University of Coimbra. The fungal strains of Aspergillus fumigatus CBS 500.90 and Alternaria infectoria CBS 137.90 CBS were obtained from CBS-KNAW Fungal Biodiversity Centre (Utrecht, The Netherlands).
Yeast strains were grown on yeast extract peptone Dextrose (YPD) agar plates with the following composition: 0.5% yeast extract (Panreac, Barcelona, Spain), 1% peptone (Panreac), 2% agar (VWR, Leuven, Belgium, and 2% glucose (Sigma-Aldrich, St. Louis, MO, USA) (w/v). Yeasts were inoculated and incubated at 30 °C for 24 h.
Filamentous fungi strains were grown on Potato Dextrose agar (PDA; Difco). T. rubrum, T. mentagrophytes, A. fumigatus, A. niger, and F. oxysporum were inoculated and incubated at 30 °C for a week. A. alternata and A. infectoria were inoculated and incubated at 28 °C for a week, with alternating 16 h light and 8 h dark cycle under a BLB blacklight blue lamp (15 W), as previously described [31 (link)].

Sporosarcina pasteurii (strain designation ATCC 11859, CCOS, 2.9 × 10¹¹ cfu g⁻¹), calcium chloride (Sigma-Aldrich, C4901), yeast extract (Panreac, A1552), ammonium sulphate (Sigma-Aldrich, A4418), trizma base (Sigma-aldrich, 93350), urea (Sigma-Aldrich, 51456), alginic acid sodium salt (low viscosity, Sigma-Aldrich, A1112), carboxymethyl cellulose (250 kDa, Sigma-Aldrich, 419303), ethylenediaminetetraacetic acid (Sigma-Aldrich, E9884).