Filamentous sulfur bacteria, Beggiatoa spp., in arctic marine sediments (Svalbard, 79 degrees N).
ABSTRACT Fjord sediments on the west coast of the arctic archipelago Svalbard were surveyed to understand whether large filamentous sulfur bacteria of the genus Beggiatoa thrive at seawater temperatures permanently near freezing. Two sediments had abundant populations of Beggiatoa, while at six sites, only sporadic occurrences were observed. We conclude that Beggiatoa, although previously unnoticed, are widespread in these arctic fjord sediments. Beggiatoa ranged in diameter from 2 to 52 microm and, by those tested, stored nitrate in vacuoles at up to 260 mM. The 16S rRNA gene sequence of a 20-microm-wide filament is closely associated with other large, marine, nitrate-storing Beggiatoa. The Beggiatoa mostly occurred in the upper 2-5 cm of oxidized surface sediment between oxygen and the deeper sulfidic zone. In spite of a very low or an undetectable sulfide concentration, sulfate reduction provided abundant H(2)S in this zone. The total living biomass of Beggiatoa filaments at one study site varied over 3 years between 1.13 and 3.36 g m(-2). Because of their large size, Beggiatoa accounted for up to 15% of the total prokaryotic biomass, even though the filament counts at this site were rather low, comprising <1/10,000 of the bacterial numbers on a cell basis.
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ABSTRACT: The response of gliding motility to changing temperatures was studied in filaments of the large sulfur bacteria Beggiatoa from arctic, temperate and tropical marine environments. The general shape of the gliding speed vs. temperature curves from all three locations was similar, but differed in the maximal gliding speed of the filaments, optimum temperature and the temperature range of motility. The optimum temperature and the overall temperature range of gliding motility accorded to the climatic origin of the filaments with a high temperature range for tropical, an intermediate range for temperate, and a low temperature range for arctic filaments. The temperature-controlled decrease in gliding speed at low temperatures was reversible while the decline in speed at high temperatures was due to irreversible thermal damage in individual filaments. Filaments from the Arctic and cold-acclimatized filaments from the temperate zone were unaffected by transient freezing of the surrounding seawater. At in situ temperatures, filaments glided at 17-55% of the gliding speed at the optimum temperatures, indicating that they were well adapted to the temperature regime of their origin. Our results point towards an enzymatic control of temperature-dependent gliding motility.FEMS Microbiology Ecology 08/2010; 73(2):234-42. · 3.56 Impact Factor
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ABSTRACT: The ecological niche of nitrate-storing Beggiatoa, and their contribution to the removal of sulfide were investigated in coastal sediment. With microsensors a clear suboxic zone of 2–10 cm thick was identified, where neither oxygen nor free sulfide was detectable. In this zone most of the Beggiatoa were found, where they oxidize sulfide with internally stored nitrate. The sulfide input into the suboxic zone was dominated by an upward sulfide flux from deeper sediment, whereas the local production in the suboxic zone was much smaller. Despite their abundance, the calculated sulfide-oxidizing capacity of the Beggiatoa could account for only a small fraction of the total sulfide removal in the sediment. Consequently, most of the sulfide flux into the suboxic layer must have been removed by chemical processes, mainly by precipitation with Fe2+ and oxidation by Fe(III), which was coupled with a pH increase. The free Fe2+ diffusing upwards was oxidized by Mn(IV), resulting in a strong pH decrease. The nitrate storage capacity allows Beggiatoa to migrate randomly up and down in anoxic sediments with an accumulated gliding distance of 4 m before running out of nitrate. We propose that the steep sulfide gradient and corresponding high sulfide flux, a typical characteristic of Beggiatoa habitats, is not needed for their metabolic performance, but rather used as a chemotactic cue by the highly motile filaments to avoid getting lost at depth in the sediment. Indeed sulfide is a repellant for Beggiatoa.Keywords: microsensor, chemotaxis, geochemistry, suboxic zone, sulfate reduction, nitrate reductionThe ISME Journal 06/2007; 1(4):341-353. · 8.95 Impact Factor
- Limnology and Oceanography - LIMNOL OCEANOGR. 01/1967; 12(1):163-165.
Motility of the giant sulfur bacteria
Beggiatoa in the marine environment
Motility of the giant sulfur bacteria Beggiatoa in the marine
zur Erlangung des Doktorgrades der Naturwissenschaften
Dr. rer. nat.
von Rita Dunker, Master of Science (MSc)
geboren am 22. August 1975 in Köln
der Universität Bremen
Prof. Dr. Bo Barker Jørgensen
Prof. Dr. Ulrich Fischer
Datum des Promotionskolloquiums:
15. Dezember 2010
Table of contents
1.1 Characteristics of Beggiatoa
1.2 Beggiatoa in their environment
1.3 Temperature response in Beggiatoa
1.4 Gliding motility in Beggiatoa
1.5 Chemotactic responses
2.1 Mansucript 1: Temperature regulation of gliding
motility in filamentous sulfur bacteria, Beggiatoa spp.
2.2 Mansucript 2: Filamentous sulfur bacteria, Beggiatoa
spp. in arctic, marine sediments (Svalbard, 79° N)
2.3. Manuscript 3: Motility patterns of filamentous sulfur
bacteria, Beggiatoa spp.
2.4. A new approach to Beggiatoa spp. behavior in an
Conclusions and Outlook
Contribution to manuscripts 137