Table 1:
Examples of experimentally validated iron uptake systems in gut bacteria
| Phylum | Iron source or siderophore | Transporter/receptor (in exemplary organisms) | Reference |
|---|---|---|---|
| Bacteroidetes | Heme | HupA | (Chen and Wolin 1981) |
| FeoAB in conjunction with BtuS1 and BtuS2 (Bacteroides fragilis) | (Otto et al. 1996) (Rocha et al. 2018) | ||
| Ferrous iron | FeoAB (Bacteroides fragilis) | (Rocha et al. 1991) | |
| Ferric iron | Unknown | (Rocha et al. 1991) | |
| Ferrichrome | FchA1/FchA2 (B. fragilis) | (Rocha and Krykunivsky 2017) | |
| Enterobactin | Unknown | (Rocha and Krykunivsky 2017) | |
| Salmochelin | Unknown | (Rocha and Krykunivsky 2017) | |
| Firmicutes | Ferric citrate | YfmCDEF (Bacillus subtilis) | (Ollinger et al. 2006) |
| Ferrous iron | FeoAB (Clostridium perfringens) | (Awad et al. 2016) | |
| Heme | ChtD/ChtE (C. perfringens) | (Choo et al. 2016) | |
| Hemoglobin | Unknown (Prevotella intermedia) | (Leung et al. 1998) | |
| Bacillibactin/Enterobactin | FeuA (B. subtilis) | (Peuckert et al. 2011) | |
| Ferrichrome | FhuDBGC (B. subtilis) | (Schneider and Hantke 1993) | |
| Ferrioxamine B | FoxD FhuBGC (B. subtilis) | (Schneider and Hantke 1993) | |
| Schizokinen | YfhA/YfiYZ (B. subtilis) | (Ollinger et al. 2006) | |
| Transferrin and lactoferrin | Unknown (Enterococcus faecalis) | (Lisiecki 2017) | |
| Ferric-2-oxoacid complex | Unknown (E. faecalis) | (Lisiecki and Mikucki 2006) | |
| Hydroxamate | Unknown (Enterococcus spp.) | (Sobis-Glinkowska et al. 2001) | |
| Proteobacteria (Enterobacteriaceae) | Ferrous iron | FeoAB (Escherichia coli) | (Kammler et al. 1993) |
| Ferric citrate | FecABCDE (E. coli) | (Wagegg and Braun 1981) | |
| Heme | ChuA (EHEC) | (Torres and Payne 1997) | |
| Enterobactin | FepABCDG (S. Typhimurium) | (Rutz et al. 1991) | |
| Yersiniabactin | FyuA (Yersinia, EHEC) | (Schubert et al. 1998) | |
| Salmochelin | IroN (S. Typhimurium) | (Baumler et al. 1998) | |
| Dihydroxybenzoate | CirA (E. coli) | (Cardelli and Konisky 1974; Hantke 1990) | |
| Fiu (E. coli) | |||
| Ferrichrome | FhuA (S. Typhimurium) | (Tsolis et al. 1995) | |
| Bifidobacterium | Lactoferrin | Unknown | (Oda et al. 2014; Petschow and Talbott 1991) |