TABLE 2.
Identification of sequences from DGGE bands of enrichment cultures and physiological characteristics of closest relatives
| Name and sampling site | Enrichment medium and technique | Characteristics and morphology | Closest cultured relative and origin of relative | Closest known relative able to oxidize/reduce Fe |
|---|---|---|---|---|
| Microaerophilic Fe(II) oxidizer S1 Oct. c; Norsminde Fjord | ZVI plates with ASW; dilution to extinction | Bean-shaped cells ca. 0.4 μm wide and 1 μm long; makes filigree stalks with several filaments; motile | Mariprofundus sp. M34 (98% sequence similarity); isolated from an iron mat at Loihi Seamount (HI) (76) | Mariprofundus sp. M34 (98% sequence similarity); isolated from an iron mat at Loihi Seamount (HI) (76) |
| Microaerophilic Fe(II) oxidizer S2.5; Kalø Vig | ZVI plates with ASW; dilution to extinction | Bean-shaped cells ca. 0.4 μm wide and 1 μm long; makes rigid stalks; motile | Mariprofundus sp. M34 (98% sequence similarity); isolated from an iron mat at Loihi Seamount (HI) (76) | Mariprofundus sp. M34 (98% sequence similarity); isolated from an iron mat at Loihi Seamount (HI) (76) |
| Photoferrotroph S1.1; Norsminde Fjord | ASW with Fe(II) in light; dilution to extinction | Rod-shaped cells ca. 0.5–0.6 μm wide and 1.6–1.5 μm long; closely associated with iron minerals; can also grow photolithotrophically with hydrogen or photoheterotrophically with organic acids like lactate | C. luteolum (99% sequence similarity); isolated from a freshwater ditch close to the river Rhine (100, 111) | C. ferrooxidans KoFox (93% sequence similarity); isolated from a freshwater ditch close to Constance (24) |
| Photoferrotroph S2.2; Kalø Vig | ASW with Fe(II) in light; dilution to extinction | Two different morphotypes: smaller rod-shaped cells ca. 0.2–0.3 μm wide and 1 μm long and larger rod-shaped cells 0.5 μm wide and 2–3 μm long; closely associated with iron minerals; can also grow aerobic on R2A ASW-agar plates, where red and yellow colonies form | Rhodobacter sp. SW2 (99% sequence similarity); isolated from a freshwater pond close to Hannover (5) | Rhodobacter sp. SW2 |
| M. purpuratum (98% sequence similarity); isolated from a marine sponge (112) | Rhodobacter sp. SW2 (84% sequence similarity) | |||
| Nitrate-reducing Fe(II) oxidizer S1.5; Norsminde Fjord | ASW with Fe(II), NO3−, and acetate; dilution to extinction and agar shakes | Long rod-shaped cells ca. 0.5 μm wide and 2.5–3 μm long; tightly associated with iron minerals; encrusted with iron minerals | H. marina (99% sequence similarity); isolated from the Baltic Sea (113) | H. siderophila (99% sequence similarity); isolated from an iron-rich spring in Russia (97) |
| Nitrate-reducing Fe(II) oxidizer S2.5; Kalø Vig | ASW with Fe(II), NO3−, and acetate; dilution to extinction and agar shakes | Long rod-shaped cells ca. 0.5 μm wide and 2 μm long; tightly associated with iron minerals; encrusted with iron minerals | D. indolicum strain MPKc (99% sequence similarity) isolated from sediment from Bay of Hong Kong (C. W. Yip and J. D. Gu, unpublished data) | D. aromatica RCB (91% sequence similarity); isolated from sediments of the Potomac River, USA (114) |
| Fe(III) reducer S1.3; Norsminde Fjord | ASW with Fe(III), acetate, and lactate; dilution to extinction | Rod-shaped cells ca. 0.5 μm wide and 2 μm long; grow associated with iron minerals | S. colwelliana (99% sequence similarity); isolated from an estuarine aquaculture of oysters (111) | S. colwelliana (99% sequence similarity); isolated from an estuarine aquaculture of oysters (111) |
| Fe(III) reducer S2.3; Kalø Vig | ASW with Fe(III), acetate, and lactate; dilution to extinction | Rod-shaped cells ca. 0.5 μm wide and 2 μm long; grow associated with iron minerals | S. colwelliana (99% sequence similarity); isolated from an estuarine aquaculture of oysters (115) | S. colwelliana (99% sequence similarity); isolated from an estuarine aquaculture of oysters (115) |