Sulfate-reducing bacteria that produce exopolymers thrive in the calcifying zone of a hypersaline cyanobacterial mat

Journal Article (2019)
Author(s)

Stefan Spring (Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures)

Dimitry Y. Sorokin (TU Delft - BT/Environmental Biotechnology, Winogradsky Institute of Microbiology)

Susanne Verbarg (Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures)

Manfred Rohde (Helmholtz Centre for Infection Research (HZI))

Tanja Woyke (Joint Genome Institute)

Nikos C. Kyrpides (Joint Genome Institute)

Research Group
BT/Environmental Biotechnology
Copyright
© 2019 Stefan Spring, Dimitry Y. Sorokin, Susanne Verbarg, Manfred Rohde, Tanja Woyke, Nikos C. Kyrpides
DOI related publication
https://doi.org/10.3389/fmicb.2019.00862
More Info
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Publication Year
2019
Language
English
Copyright
© 2019 Stefan Spring, Dimitry Y. Sorokin, Susanne Verbarg, Manfred Rohde, Tanja Woyke, Nikos C. Kyrpides
Research Group
BT/Environmental Biotechnology
Issue number
APR
Volume number
10
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Abstract

Calcifying microbial mats in hypersaline environments are important model systems for the study of the earliest ecosystems on Earth that started to appear more than three billion years ago and have been preserved in the fossil record as laminated lithified structures known as stromatolites. It is believed that sulfate-reducing bacteria play a pivotal role in the lithification process by increasing the saturation index of calcium minerals within the mat. Strain L21-Syr-ABT was isolated from anoxic samples of a several centimeters-thick microbialite-forming cyanobacterial mat of a hypersaline lake on the Kiritimati Atoll (Kiribati, Central Pacific). The novel isolate was assigned to the family Desulfovibrionaceae within the Deltaproteobacteria. Available 16S rRNA-based population surveys obtained from discrete layers of the mat indicate that the occurrence of a species-level clade represented by strain L21-Syr-ABT is restricted to a specific layer of the suboxic zone, which is characterized by the presence of aragonitic spherulites. To elucidate a possible function of this sulfate-reducing bacterium in the mineral formation within the mat a comprehensive phenotypic characterization was combined with the results of a comparative genome analysis. Among the determined traits of strain L21-Syr-ABT, several features were identified that could play a role in the precipitation of calcium carbonate: (i) the potential deacetylation of polysaccharides and consumption of substrates such as lactate and sulfate could mobilize free calcium; (ii) under conditions that favor the utilization of formate and hydrogen, the alkalinity engine within the mat is stimulated, thereby increasing the availability of carbonate; (iii) the production of extracellular polysaccharides could provide nucleation sites for calcium mineralization. In addition, our data suggest the proposal of the novel species and genus Desulfohalovibrio reitneri represented by the type strain L21-Syr-ABT (=DSM 26903T = JCM 18662T).

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