Ability of bacteroides species to obtain iron from iron salts, haem-compounds and transferrin

Abstract

Of the five Bacteriodes species of the ‘fragilis group’ only Bacteroides fragilis was able to grow in human plasma. Therefore the capacity of several iron sources to stimulate to growth of Bacteroides species under iron restricted conditions in vitro was tested. The iron chelator bipyridyl was used for the restriction of iron in the media. Ferrous sulphate, ferric ammonium sulphate and ferric citrate stimulated the growth of all five Bacteroides species tested to the same extent. B. fragilis, and to a lesser extent B.thetaiotaomicron and B. distasonis were better able than B. vulgatus and B. ovatus to use haem‐compounds as an iron source in the presence of the iron chelator bipyridyl. All five Bacteroides species tested could use 30% iron‐saturated transferrin. There was no correlation between the ability of the strains to grow in human plasma and the ability to use either haem‐compounds of transferrin as a source of iron.

Anaerobic utilization of Fe(III)‐xenosiderophores among Bacteroides species and the distinct assimilation of Fe(III)‐ferrichrome by Bacteroides fragilis within the genus

“…However, growth of B. vulgatus 40G2‐33 and 20‐15 can occur in the presence of heme if Fe(III)‐enterobactin (Figure b) or inorganic iron are provided exogenously (Figure a). In contrast, the control strains B. vulgatus 10–9 and 16–4 isolated from healthy individuals and B. fragilis grew on heme alone as expected (Figure c) since in the absence of exogenous iron, iron can be obtained from heme (Rocha et al., ; Sperry et al., ; Verweij‐Van Vught, Otto, Namavar, Sparrius, & Maclaren, ). It is important to mention that growth of Bacteroides species is not stimulated in media lacking heme or protoporhyrin IX (Rocha et al., ; Sperry et al., ; Verweij‐Van Vught et al., ).…”

“…In contrast, the control strains B. vulgatus 10–9 and 16–4 isolated from healthy individuals and B. fragilis grew on heme alone as expected (Figure c) since in the absence of exogenous iron, iron can be obtained from heme (Rocha et al., ; Sperry et al., ; Verweij‐Van Vught, Otto, Namavar, Sparrius, & Maclaren, ). It is important to mention that growth of Bacteroides species is not stimulated in media lacking heme or protoporhyrin IX (Rocha et al., ; Sperry et al., ; Verweij‐Van Vught et al., ). Taken together, these findings clearly show that intestinal Bacteroides species have developed different strategies to acquire heme‐iron and Fe(III)‐siderophores for growth under iron‐limiting conditions anaerobically.…”

Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia: the ‘red complex’, a prototype polybacterial pathogenic consortium in periodontitis

“…Pathogenic bacteria have developed numerous mechanisms to acquire iron within microenvironments, including endogenous/exogenous siderophores (151), binding host iron proteins (335), and other more limited processes including hemolysins (465). Utilization and transport of hemin and hemin‐containing compounds for nutritional iron has been documented for numerous pathogenic bacteria, including Vibrio cholerae, Neiserria gonorrheae, B. fragilis , P. aeruginosa, Yersinia pestis (264, 431) and Hemophilus influenzae (101, 124, 294, 344, 413, 445). Fe +2 iron is quite soluble, and microbes living in anaerobic environments need no specialized strategies for solubilizing iron.…”

Iron and heme utilization inPorphyromonas gingivalis

“…In vitro, P. gingivalis grows well in a medium containing hemin or hemoglobin as an iron source; however, the concentration of hemoglobin required to support its growth is much lower than that of hemin (1.7 · 10 À9 M and 1-5 · 10 À6 M, respectively) [78,79]. The gingival crevicular fluid present in diseased periodontal pockets contains a variety of proteins carrying iron or heme, including transferrin and hemoglobin [80,81].…”