Bacillus subtilis

LAB isolates were grown on de Man, Rogosa & Sharpe (MRS) agar (Laboratories Conda S.A., Madrid, Spain) at 37°C. The indicator strains were obtained from the American Type Culture Collection (ATCC) and cultivated as follows: Staphylococcus aureus (ATCC-6538) on brain heart infusion (BHI) agar (Oxoid, Basingstoke, UK); Escherichia coli (ATCC- 8739), Bacillus subtilis (ATCC-6633) and Pseudomonas aeruginosa (ATCC-9027) on Luria Bertani (LB) agar (Oxoid, Basingstoke, UK); Candida albicans (ATCC 10231) on yeast mold (YM) agar (Difco, Franklin Lakes, NJ, USA).

The two bacterial strains PA and BN were used as materials to evaluate their function in ameliorating HFe-induced cognitive impairment. The two strains were isolated from naturally fermented pickles and fermented soybean paste, respectively. These strains were preserved in the China General Microbiological Culture Collection Center (CGMCC; Pediococcus acidilactici CGMCC No. 24714 and Bacillus subtilis CGMCC No.15635) and were cultured in de Man, Rogosa and Sharpe broth (Oxoid, Hampshire,UK) at 37 °C for 18 h. The fermented broth was collected and dried as bacterial powder. Freeze-dried bacteria were prepared for gavage using a freeze-dryer (Christ α-2-4LD plus, Germany).
Escherichia coli (E. coli) strain OP50 was obtained from the Institute of Rate Biophysics of Chinese Academy of Sciences and cultured in Luria–Bertani medium (Oxoid) at 37 °C for 18 h.
The tau transgenic C.elegans strain VH254 [pha-1 (e2123) III; hdEx81)], expressing FLAG-human pseudohyperphosphorylated tau, was purchased from the Caenorhabditis Genetics Center (University of Minnesota, USA). VH254 strain was cultured at 25 °C on Nematode Growth Medium (NGM) plates using living E. coli strain OP50 as food.