Conference talk
J. Finck, R. E. Cooper, K. Küsel
MiCom, Jena, GERMANY, 2021
MiCom, Jena, GERMANY, 2021
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APA
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Finck, J., Cooper, R. E., & Küsel, K. (2021). From autotrophy to mixotrophy: Metabolic versatility of the Fe(II)-oxidizing Sideroxydans sp. CL21. MiCom, Jena, GERMANY.
Chicago/Turabian
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Finck, J., R. E. Cooper, and K. Küsel. “From Autotrophy to Mixotrophy: Metabolic Versatility of the Fe(II)-Oxidizing Sideroxydans Sp. CL21.” MiCom, Jena, GERMANY, 2021.
MLA
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Finck, J., et al. From Autotrophy to Mixotrophy: Metabolic Versatility of the Fe(II)-Oxidizing Sideroxydans Sp. CL21. MiCom, Jena, GERMANY, 2021.
BibTeX Click to copy
@conference{j2021a,
title = {From autotrophy to mixotrophy: Metabolic versatility of the Fe(II)-oxidizing Sideroxydans sp. CL21},
year = {2021},
publisher = {MiCom, Jena, GERMANY},
author = {Finck, J. and Cooper, R. E. and Küsel, K.}
}
Abstract
Fe(II)-oxidizing bacteria (FeOB) have long been recognized as important contributors
to biogeochemical cycles, yet the complete understanding of their physiology is not
known. Many known FeOB, including Sideroxydans spp. found within the
Gallionellaceae family, exhibit a wide variety of autotrophic pathways (Emerson et al.,
2013). Sideroxydans spp. inhabiting the slightly acidic, minerotrophic, and Fe-rich
Schlöppnerbrunnen fen (Northern Bavaria, Germany) are among the most abundant
FeOB from 0-30 cm. Sideroxydans sp. CL21, a gram-negative FeOB, was previously
isolated from this fen and encodes genes linked to Fe(II) oxidation (mto), sulfur
oxidation (sox), and lactate utilization (lld) gene clusters, as well as genes encoding
[NiFe] hydrogenases (Cooper et al., 2020). The occurrence of these genes suggests
an atypical mixotrophic metabolism, unlike its close relative S. lithotrophicus ES-1, a
chemolithoautotroph (Emerson et al., 2013; Kato et al., 2015). To elucidate the
metabolic capabilities of Sideroxydans sp. CL21, semi-solid and liquid incubations
were amended with an organic C source (lactate or acetate, 0-5 mM) and various
combinations of alternative electron donors, including H2 (0 or 5%), NaS2O3 (0-5 mM),
Fe0
(1 g L
-1
) and FeS. All of the tested electron donors, as well as lactate, could be
utilized by Sideroxydans sp. CL21 to fuel its metabolism. Incubations that were
amended with a combination of a single electron donor and 1 mM lactate yielded higher
16S rRNA gene copies, compared to incubations amended with a single electron
donor. Incubations with lactate plus Fe0 or FeS both displayed a significant increase
(Fe0
: p < 0.010; FeS: p < 0.050) in 16S rRNA gene copies over time, resulting in 2-8x
better growth, depending on the Fe source. The highest 16S rRNA gene copies were
found in incubations with 1 mM lactate plus H2 and Fe as double electron donors,
featuring 16x better growth then incubations with Fe only. The rates of H2 and O2
utilization in H2 plus Fe incubations were 5.3x and 2.7x higher in the presence of an
organic carbon source, suggesting H2 may be the preferred electron donor in presence
of organic carbon substrates. Taken together, the experimental results illustrate the
versatility of Sideroxydans sp. CL21. This metabolic flexibility proves advantageous in
the Schlöppnerbrunnen fen, which is rich in reduced sulfur compounds, organic carbon
substrates in the form of DOM, H2, and Fe, thus enabling strain CL21 to outcompete
other FeOB by occupying a wide variety of ecological niches.
to biogeochemical cycles, yet the complete understanding of their physiology is not
known. Many known FeOB, including Sideroxydans spp. found within the
Gallionellaceae family, exhibit a wide variety of autotrophic pathways (Emerson et al.,
2013). Sideroxydans spp. inhabiting the slightly acidic, minerotrophic, and Fe-rich
Schlöppnerbrunnen fen (Northern Bavaria, Germany) are among the most abundant
FeOB from 0-30 cm. Sideroxydans sp. CL21, a gram-negative FeOB, was previously
isolated from this fen and encodes genes linked to Fe(II) oxidation (mto), sulfur
oxidation (sox), and lactate utilization (lld) gene clusters, as well as genes encoding
[NiFe] hydrogenases (Cooper et al., 2020). The occurrence of these genes suggests
an atypical mixotrophic metabolism, unlike its close relative S. lithotrophicus ES-1, a
chemolithoautotroph (Emerson et al., 2013; Kato et al., 2015). To elucidate the
metabolic capabilities of Sideroxydans sp. CL21, semi-solid and liquid incubations
were amended with an organic C source (lactate or acetate, 0-5 mM) and various
combinations of alternative electron donors, including H2 (0 or 5%), NaS2O3 (0-5 mM),
Fe0
(1 g L
-1
) and FeS. All of the tested electron donors, as well as lactate, could be
utilized by Sideroxydans sp. CL21 to fuel its metabolism. Incubations that were
amended with a combination of a single electron donor and 1 mM lactate yielded higher
16S rRNA gene copies, compared to incubations amended with a single electron
donor. Incubations with lactate plus Fe0 or FeS both displayed a significant increase
(Fe0
: p < 0.010; FeS: p < 0.050) in 16S rRNA gene copies over time, resulting in 2-8x
better growth, depending on the Fe source. The highest 16S rRNA gene copies were
found in incubations with 1 mM lactate plus H2 and Fe as double electron donors,
featuring 16x better growth then incubations with Fe only. The rates of H2 and O2
utilization in H2 plus Fe incubations were 5.3x and 2.7x higher in the presence of an
organic carbon source, suggesting H2 may be the preferred electron donor in presence
of organic carbon substrates. Taken together, the experimental results illustrate the
versatility of Sideroxydans sp. CL21. This metabolic flexibility proves advantageous in
the Schlöppnerbrunnen fen, which is rich in reduced sulfur compounds, organic carbon
substrates in the form of DOM, H2, and Fe, thus enabling strain CL21 to outcompete
other FeOB by occupying a wide variety of ecological niches.