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A new lineage of halophilic, wall-less, contractile bacteria from a brine-filled deep of the Red Sea.

ABSTRACT: A novel strictly anaerobic bacterium designated strain SSD-17B(T) was isolated from the hypersaline brine-sediment interface of the Shaban Deep, Red Sea. Cells were pleomorphic but usually consisted of a central coccoid body with one or two "tentacle-like" protrusions. These protrusions actively alternated between a straight, relaxed form and a contracted, corkscrew-like one. A peptidoglycan layer was not detected by electron microscopy. The organism forms "fried-egg"-like colonies on MM-X medium. The organism is strictly anaerobic and halophilic and has an optimum temperature for growth of about 30 to 37 degrees C and an optimum pH of about 7. Nitrate and nitrite are reduced; lactate is a fermentation product. The fatty acid profile is dominated by straight saturated and unsaturated chain compounds. Menaquinone 4 is the major respiratory quinone. Phylogenetic analysis demonstrated strain SSD-17B(T) represents a novel and distinct lineage within the radiation of the domain Bacteria. The branching position of strain SSD-17B(T) was equidistant to the taxa considered to be representative lineages of the phyla Firmicutes and Tenericutes (with its sole class Mollicutes). The phenotypic and phylogenetic data clearly show the distinctiveness of this unusual bacterium, and we therefore propose that strain SSD-17B(T) (= DSM 18853 = JCM 14575) represents a new genus and a new species, for which we recommend the name Haloplasma contractile gen. nov., sp. nov. We are also of the opinion that the organism represents a new order-level taxon, for which we propose the name Haloplasmatales.

SUBMITTER: Antunes A

PROVIDER: S-EPMC2394993 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature

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A new lineage of halophilic, wall-less, contractile bacteria from a brine-filled deep of the Red Sea.

Antunes André A Rainey Fred A FA Wanner Gerhard G Taborda Marco M Pätzold Jürgen J Nobre M Fernanda MF da Costa Milton S MS Huber Robert R

Journal of bacteriology 20080307 10

A novel strictly anaerobic bacterium designated strain SSD-17B(T) was isolated from the hypersaline brine-sediment interface of the Shaban Deep, Red Sea. Cells were pleomorphic but usually consisted of a central coccoid body with one or two "tentacle-like" protrusions. These protrusions actively alternated between a straight, relaxed form and a contracted, corkscrew-like one. A peptidoglycan layer was not detected by electron microscopy. The organism forms "fried-egg"-like colonies on MM-X mediu ...[more]

PMID: 18326567

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Project description:Homoacetogens are efficient CO2 fixing bacteria using H2 as electron donor to produce acetate. These organisms can be enriched at the biocathode of microbial electrosynthesis (MES) for electricity-driven CO2 reduction to acetate. Studies exploring homoacetogens in MES are mainly conducted using pure or mix-culture anaerobic inocula from samples with standard environmental conditions. Extreme marine environments host unique microbial communities including homoacetogens that may have unique capabilities due to their adaptation to harsh environmental conditions. Anaerobic deep-sea brine pools are hypersaline and metalliferous environments and homoacetogens can be expected to live in these environments due to their remarkable metabolic flexibility and energy-efficient biosynthesis. However, brine pools have never been explored as inocula for the enrichment of homacetogens in MES. Here we used the saline water from a Red Sea brine pool as inoculum for the enrichment of halophilic homoacetogens at the biocathode (-1 V vs. Ag/AgCl) of MES. Volatile fatty acids, especially acetate, along with hydrogen gas were produced in MES systems operated at 25 and 10% salinity. Acetate concentration increased when MES was operated at a lower salinity ∼3.5%, representing typical seawater salinity. Amplicon sequencing and genome-centric metagenomics of matured cathodic biofilm showed dominance of the genus Marinobacter and phylum Firmicutes at all tested salinities. Seventeen high-quality draft metagenome-assembled genomes (MAGs) were extracted from the biocathode samples. The recovered MAGs accounted for 87 ± 4% of the quality filtered sequence reads. Genome analysis of the MAGs suggested CO2 fixation via Wood-Ljundahl pathway by members of the phylum Firmicutes and the fixed CO2 was possibly utilized by Marinobacter sp. for growth by consuming O2 escaping from the anode to the cathode for respiration. The enrichment of Marinobacter sp. with homoacetogens was only possible because of the specific cathodic environment in MES. These findings suggest that in organic carbon-limited saline environments, Marinobacter spp. can live in consortia with CO2 fixing bacteria such as homoacetogens, which can provide them with fixed carbon as a source of carbon and energy.

Dataset Information

A new lineage of halophilic, wall-less, contractile bacteria from a brine-filled deep of the Red Sea.

Publications

A new lineage of halophilic, wall-less, contractile bacteria from a brine-filled deep of the Red Sea.

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