Tryptose

Hemin, EDTA, NADH, RPMI-1640 culture medium, dithionitrobenzoate (DTNB) and L(+) ascorbic acid GR (Vit C) were obtained from Sigma Chem. Co. (Saint Louis, MO, USA). Yeast extract, tryptose and brain heart infusion (BHI) were from Difco Laboratories (Sparks, MD, USA). Bnz was kindly provided by Roche (Argentina). All other chemicals were of the highest purity commercially available.

Bifidobacterium bifidum YIT 10347 (BF-1) was used as a wild-type (WT) strain. The complete genome sequence (2,149,912 bp) of BF-1 (GenBank: AP024712) was found to be similar to that of B. bifidum PRL2010 (Turroni et al., 2010 (link)). BF-1 and its mutants were anaerobically cultured at 37°C in de Man–Rogosa–Sharpe (MRS) medium (Difco Laboratories, Detroit, MI, USA) supplemented with 0.05% L-cysteine HCl or in modified ILS (m-ILS) medium containing 10 g trypticase peptone (Difco Laboratories), 5 g yeast extract (Difco Laboratories), 3 g tryptose (Difco Laboratories), 10 g lactose, 3 g KH₂PO₄, 3 g K₂HPO₄, 2 g tri-ammonium citrate, 1 mL pyruvate, 0.3 g L-cysteine HCl, 1 mL Tween 80 (Sigma-Aldrich, St. Louis, MO, USA), 0.575 g MgSO₄·7H₂0, 0.12 g MnSO₄·4H₂0, and 0.034 g FeSO₄·7H₂O in 1.0 L distilled water (pH 6.8).
To count viable bacteria (CFUs), serial dilutions of the samples were plated on agar plates containing MRS medium supplemented with 0.05% L-cysteine HCl and cultured at 37°C. Preparation of the dilutions and cultures was carried out anaerobically.
Escherichia coli JM109 (Takara Bio, Shiga, Japan) were used as competent cells for plasmid construction; they were aerobically cultured at 37°C in Luria–Bertani medium (Difco Laboratories).

Psi and PsiC have been isolated from Ambrosia tenuifolia and Ambrosia scabra, respectively [5 (link), 8 (link)]. The purity of Psi and PsiC was 96.8 and 95.5%, respectively as confirmed by high-performance liquid chromatography (HPLC) analysis.
Standard solutions of these compounds were prepared in dimethyl sulphoxide (DMSO) at a final concentration that never exceeded 0.5%. Hemin, artemisinin, NADPH, Rh123 and H₂DCFDA were obtained from Sigma Chem. Co. (Saint Louis, MO, USA). Yeast extract, tryptose, powered beef liver and brain heart infusion were from Difco Laboratories (Sparks, MD, USA). Benznidazole (Bnz) was kindly provided by Roche (Argentina). All other chemicals were of the highest purity commercially available.