Competition in the Chemostat between an Obligately and a Facultatively Chemolithotrophic Thiobacillus

Smith, Alison; Kelly, Donovan P.

doi:10.1099/00221287-115-2-377

Cited by 32 publications

(23 citation statements)

References 23 publications

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“…However, so far, there is no fully satisfactory answer to this question (52). It is believed that obligate chemolithoautotrophs have some advantages compared to facultative chemolithoautotrophs, e.g., the specialization by having a higher substrate affinity than facultative chemolithoautotrophs, as observed for some aerobic sulfur oxidizers (53)(54)(55). However, the disadvantage is that they are dependent on the occurrence of specific environmental conditions in order to be active and oxidize iron(II).…”

Section: Figmentioning

confidence: 95%

Microaerophilic Fe(II)-Oxidizing Zetaproteobacteria Isolated from Low-Fe Marine Coastal Sediments: Physiology and Composition of Their Twisted Stalks

Laufer

Nordhoff

Halama

et al. 2017

Appl Environ Microbiol

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Microaerophilic Fe(II) oxidizers are commonly found in habitats containing elevated Fe(II) and low O 2 concentrations and often produce characteristic Fe mineral structures, so-called twisted stalks or tubular sheaths. Isolates originating from freshwater habitats are all members of the Betaproteobacteria, while isolates from marine habitats belong almost exclusively to the Zetaproteobacteria. So far, only a few isolates of marine microaerophilic Fe(II) oxidizers have been described, all of which are obligate microaerophilic Fe(II) oxidizers and have been thought to be restricted to Fe-rich systems. Here, we present two new isolates of marine microaerophilic Fe(II)-oxidizing Zetaproteobacteria that originate from typical coastal marine sediments containing only low Fe concentrations (2 to 11 mg of total Fe/g of sediment [dry weight]; 70 to 100 M dissolved Fe 2ϩ in the porewater). The two novel Zetaproteobacteria share characteristic physiological properties of the Zetaproteobacteria group, even though they come from low-Fe environments: the isolates are obligate microaerophilic Fe(II) oxidizers and, like most isolated Zetaproteobacteria, they produce twisted stalks. We found a low organic carbon content in the stalks (ϳ0.3 wt%), with mostly polysaccharides and saturated aliphatic chains (most likely lipids). The Fe minerals in the stalks were identified as lepidocrocite and possibly ferrihydrite. Immobilization experiments with Ni 2ϩ showed that the stalks can function as a sink for trace metals. Our findings show that obligate microaerophilic Fe(II) oxidizers belonging to the Zetaproteobacteria group are not restricted to Fe-rich environments but can also be found in low-Fe marine environments, which increases their overall importance for the global biogeochemical Fe cycle.IMPORTANCE So far, only a few isolates of benthic marine microaerophilic Fe(II) oxidizers belonging to the Zetaproteobacteria exist, and most isolates were obtained from habitats containing elevated Fe concentrations. Consequently, it was thought that these microorganisms are important mainly in habitats with high Fe concentrations. The two novel isolates of Zetaproteobacteria that are presented in the present study were isolated from typical coastal marine sediments that do not contain elevated Fe concentrations. This increases the knowledge about possible habitats in which Zetaproteobacteria can exist. Furthermore, we show that the physiology and the typical organo-mineral structures (twisted stalks) that are produced by the isolates do not notably differ from the physiology and the cell-mineral structures of

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Section: Figmentioning

confidence: 95%

Microaerophilic Fe(II)-Oxidizing Zetaproteobacteria Isolated from Low-Fe Marine Coastal Sediments: Physiology and Composition of Their Twisted Stalks

Laufer

Nordhoff

Halama

et al. 2017

Appl Environ Microbiol

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“…This seems All species were obligately chemolithotrophic motile rods ; oxidized sulfide, sulfur, thiosulfate and tetrathionate, but not thioisocyanate ; did not use nitrate as a terminal electron acceptor ; and contained ubiquinone Q-8. Data were obtained from Hutchinson et al (1965Hutchinson et al ( , 1969 ; Smith & Kelly (1979) ; Kelly & Harrison (1989) ; Durand et al (1993) ; Wood & Kelly (1991) ; McDonald et al (1997) ; Visser et al (1997) ; Kelly et al (1998) ; and own results. , Not determined.…”

Section: Ecological Significancementioning

confidence: 99%

Halothiobacillus kellyi sp. nov., a mesophilic, obligately chemolithoautotrophic, sulfur-oxidizing bacterium isolated from a shallow-water hydrothermal vent in the Aegean Sea, and emended description of the genus Halothiobacillus.

Sievert¹,

Heidorn²,

Kuever³

2000

International Journal of Systematic and Evolutionary Microbiology

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Wood 2000). Strain Milos-BII1T represents a new species of this genus, named Halothiobacillus kellyi. Cells were Gram-negative rods and highly motile. The organism was obligately autotrophic and strictly aerobic. Nitrate was not used as electron acceptor. Chemolithoautotrophic growth was observed with thiosulfate, tetrathionate, sulfur and sulfide. Growth was observed between pH values of 35 and 85, with an optimum at pH 65. The temperature limits for growth were 35 and 49 SC, with an optimum between 37 and 42 SC. Growth occurred between 0 and 2 M NaCl, with an optimum NaCl concentration between 400 and 500 mM. The mean maximum specific growth rate on thiosulfate was 045 h N1 .

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“…Recent studies have shown that the capacity for mixotrophy (the simultaneous operation of autotrophic and heterotrophic mechanisms for carbon and energy metabolism) can be of considerable advantage to facultatively mixotrophic thiobacilli in competition with specialist autotrophs or heterotrophs (Gottschal, 1980;Gottschal et al, 1979;Smith & Kelly, 1979).…”

Section: Introductionmentioning

confidence: 99%

Mixotrophic Growth of Thiobacillus A2 in Chemostat Culture on Formate and Glucose

Wood

Kelly

1981

Microbiology

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In aerobic chemostat culture Thiobacillus A2-GFI grew autotrophically on formate and heterotrophically on glucose with maximum specific growth rates (,urn,,) of 0.21 and 0.33 h-l, respectively. At dilution rates of 0.1 and 0.18 h-l, it grew mixotrophically on formate + glucose mixtures, completely consuming both substrates. Ribulose-1,5-bisphosphate carboxylase and formate dehydrogenase were present at high specific activity in autotrophic and mixotrophic cultures, but were repressed in cultures on glucose alone. A greater proportion of added glucose was assimilated in mixotrophic culture than in heterotrophic culture. Raising the dilution rate of a mixotrophic culture from 0.1 or 0.18 to 0.3 h-' resulted in washout (with an apparent p,,, for mixotrophic growth of 0.25 h-l) and the establishment of a culture dependent on glucose for growth. Growth yields on formate and glucose were, respectively, 3 -3 and 100 g dry wt (mol substrate consumed)-'. Steady state biomass production in mixotrophic culture indicated additive growth yields. The biomass produced in cultures on formate + glucose at a dilution rate of 0-3 h-l suggested that growth only occurred on glucose, but organisms still contained high activities of ribulose-1,5-bisphosphate carboxylase and formate dehydrogenase. At a formate :glucose ratio (mM) of 100 : 1, some formate was oxidized and CO, was fixed, but formate was not used when this ratio was 5 0 : 5 . Formate-glucose mixotrophy benefits Thiobacillus A2-GFI when substrates are limited at low growth rates (<,urnax for formate), but is characterized by a pmax below that possible on glucose. Physiological behaviour at high growth rates was influenced by the formate :glucose ratio, resulting under some conditions, at least, in loss of mixotrophy and the establishment of heterotrophic growth.

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Competition in the Chemostat between an Obligately and a Facultatively Chemolithotrophic Thiobacillus

Cited by 32 publications

References 23 publications

Microaerophilic Fe(II)-Oxidizing Zetaproteobacteria Isolated from Low-Fe Marine Coastal Sediments: Physiology and Composition of Their Twisted Stalks

Microaerophilic Fe(II)-Oxidizing Zetaproteobacteria Isolated from Low-Fe Marine Coastal Sediments: Physiology and Composition of Their Twisted Stalks

Halothiobacillus kellyi sp. nov., a mesophilic, obligately chemolithoautotrophic, sulfur-oxidizing bacterium isolated from a shallow-water hydrothermal vent in the Aegean Sea, and emended description of the genus Halothiobacillus.

Mixotrophic Growth of Thiobacillus A2 in Chemostat Culture on Formate and Glucose

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