Filamentous sulfur bacteria, Beggiatoa spp., in arctic marine sediments (Svalbard, 79°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 mm and, by those tested, stored nitrate in vacuoles at up to 260 mM. The 16S rRNA gene sequence of a 20-mm-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 À2 . 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 o 1/10 000 of the bacterial numbers on a cell basis.

Cable bacteria generate a firewall against euxinia in seasonally hypoxic basins

“…The biovolume was determined by measuring length (10×) and width (40×) of all filaments found in the subsample, according to ref. 45. Microscopic identification of cable bacteria was achieved by FISH, using a Desulfobulbaceae-specific oligonucleotide probe (DSB706; 5′-ACC CGT ATT CCT CCC GAT-3′), according to Schauer et al (27).…”

Structure and function of natural sulphide-oxidizing microbial mats under dynamic input of light and chemical energy

“…Thus aerobic SO by the SOB community in the B/C mats was in steady state and therefore most likely proceeded completely to sulphate (Nelson et al, 1986;Jørgensen et al, 2010). Using this stoichiometry, we estimated the energy conservation efficiency of the SOB community in the two replicate B/C mats to be 16.4% and 17.1% (calculation details given in Supplementary Information 2.2), which is very similar to the value estimated for the SOB community in the C/B mats (see above).…”

Sulphur-cycling bacteria and ciliated protozoans in a Beggiatoaceae mat covering organically enriched sediments beneath a salmon farm in a southern Chilean fjord

“…Parabeggiatoa communis sampled in the Danish Limfjorden (Mussmann et al, 2003) and Ca. Isobeggiatoa divolgata sampled in the German Wadden Sea and Svalbard in the Arctic (Jørgensen et al, 2010;Mussmann et al, 2003), both are large and vacuolated sulphur bacteria belonging to the family Beggiatoaceae recently proposed as the assigned Candidatus genera (Salman et al, 2011).…”

“…In the upper strata of the sediment the rising S −2 supports the enrichment of mat forming sulphide-oxidizing bacteria (SOB) such as Thioploca, Beggiatoa, Thiomargarita or Arcobacter (Grünke et al, 2011). The most frequently observed are the large filamentous sulphur bacteria that belong to the genera Beggiatoa [hereafter referred to as Beggiatoaceae due to the taxonomic reorganization of this family and the proposal for new genera such as Candidatus Isobeggiatoa, Candidatus Parabeggiatoa and others (Salman et al, 2011)] which maintains a chemolithotrophic metabolism using oxygen or internally stored NO 3 − to oxidize sulphide to sulphate and accumulate zero-valence sulphur (S 0 ) intermediary as colourless granules inside the cells (Jørgensen et al, 2010;Nelson and Jannasch, 1983;Nelson, Marine Pollution Bulletin xxx (2015) xxx-xxx 2006). Due to the optical properties of these granules, Beggiatoaceae cells mostly appear as white mats easily observed on submarine videos, the reason why they are widely considered as a good visual indicator of the biological response to organic enrichment of sediments due to aquaculture (Giles, 2008;Hamoutene, 2013Hamoutene, , 2014Hargrave et al, 2008;Macleod et al, 2004;Saravanakumar et al, 2012).…”

“…Due to the optical properties of these granules, Beggiatoaceae cells mostly appear as white mats easily observed on submarine videos, the reason why they are widely considered as a good visual indicator of the biological response to organic enrichment of sediments due to aquaculture (Giles, 2008;Hamoutene, 2013Hamoutene, , 2014Hargrave et al, 2008;Macleod et al, 2004;Saravanakumar et al, 2012). However, even though there are plenty of studies that address the structure, physiology and taxonomy of this interesting group of bacteria in benthic marine environments where they proliferate naturally, such as submarine sulphides at cold seeps, hydrothermal vents, seasonally hypoxic marine sediments or shelf oxygen minimum zones (Dale et al, 2013;Jørgensen et al, 2010;Larkin et al, 1994;MacGregor et al, 2013;Nelson et al, 1986a,b;Powell et al, 2012;Prince et al, 1988;Salman et al, 2011Salman et al, , 2013Schulz and Jørgensen, 2001), virtually no studies have been conducted to address those aspects of bacterial mats proliferating worldwide in sediments enriched by aquaculture (Saravanakumar et al, 2012). These studies could be key tools for understanding how impacted sediments respond to organic enrichment during intensive salmon culture, during the coordinated resting phase between culturing cycles, and during the recovery of the sediments after a fish farm has been removed.…”