Filamentous sulfur bacteria preserved in modern and ancient phosphatic
sediments: implications for the role of oxygen and bacteria in
phosphogenesis (Supplemental Information)
Jake V. Baileya*, Frank A. Corsetti b, Sarah E. Greene c, Chris H. Crosbya, Pengju Liud,
Victoria J. Orphane
a Department
MN 55455
of Earth Sciences, University of Minnesota- Twin Cities, Minneapolis,
Department of Earth Sciences, University of Southern California, Los Angeles,
California 90089-0740
b
c
School of Geographical Sciences, University of Bristol, Bristol, UK BS8 1SS
Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037,
China
d
e Division
of Geological and Planetary Sciences, California Institute of Technology,
Pasadena, CA, USA
*Corresponding author: [email protected]
Supplemental Information
Figure S1. (A) Scanning electron micrograph of partially-entombed phosphatized
filaments from the Costa Rica margin show a mineral coating (arrow) over the
exterior of the organic sheath. (B) Energy dispersive spectroscopy showing typical
apatite stoichiometry. This type of signature is present in the calcium phosphate
coating, but is less common than the signals enriched in P (see Figure 1g). This
signal may result from the excitation volume penetrating below a thin calcium
phosphate coating into the P-rich sheath material below. Scale bar in a = 100 m.
Figure S2. Light photomicrograph of Thioploca sheath after six weeks of degradation
in seawater. Elemental sulfur inclusions (dark spots) from degraded Thioploca and
Beggiatoa cells are often left behind in the sheath, where they frequently clumps
into aggregates that are larger and more disordered than the intracellular sulfur
globules from which they derive. Scale bar = 300 m.
Figure S3. Internal sulfur globules are a diagnostic feature of sulfide-oxidizing
gammaproteobacteria such as Beggiatoa (shown above), as well as Thioploca and
Thiomargarita. Scale bar = 20 m.
Figure S4. Bundles of Thioploca and individual filaments of Beggiatoa sp. (A)
commonly leave behind empty EPS sheath material (B). The sheaths can be vacated
by living bacteria, or simply left behind after the cell dies, in which case, the sheath
can contain abundant sulfur inclusions (S1). The sheath material is more resistant to
degradation than the cell material.
Figure S5. Phosphatic cherts in the Wanjiagou section of the Doushantuo Formation
host abundant filamentous structures including both septate and hollow
filamentous microfossils that resemble the sheaths and trichomes observed in
modern Beggiatoa mats (e.g., Figure S3). Scale bar = 100 m.
Figure S6. Electron microprobe profiles across the filamentous Doushantuo
microfossils shows in (A) a correlation between carbon (blue) and sulfur (green)
specifically confined to the inclusions interpreted as relict sulfur globules. No
correlation with iron (yellow) is observed in these inclusions. This signal contrasts
sharply with profiles (B) across small pyrite crystals found in the vicinity of the
microfossil (Figure 3), in which sulfur and iron are strongly correlated.
Figure S7. (A) Partial confocal laser Raman spectrum of kerogen associated with
filamentous Doushantuo microfossils showing carbon ‘D’ and ‘G’ bands. The
intensity of the G band signal from 1518.9 to 1671.5 cm-1 is mapped in the inset.
Scale bar = 6 m. The D and G bands that are characteristic of the microfossil
inclusions are sometimes accompanied by bands in the wave number range from
640–740 cm−1 that may indicate carbon-sulfur bonding in the kerogen (B-C). The C-S
stretch in modern organic matter is found in this range, but the exact position is
dependent on the backbone of the associated carbon (Jenkins et al., 2005).