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A real global player: Pre­vi­ously un­re­cog­nised bac­teria may be a key group in mar­ine sed­i­ments

Feb 17, 2020
Bre­men

From the shoreline to the deep sea, one group of bacteria is particularly widespread in our planet’s seabed: The so-called Woe­seiales, which may be feeding on the protein remnants of dead cells. Researchers from the Max Planck Institute for Marine Microbiology in Bremen and the Royal Netherlands Institute for Sea Research NIOZ now describe the distribution, diversity and lifestyle of these bacteria in The ISME Journal.

 

The research vessel Polarstern in the Arctic. (© Alfred Wegener Institute / Stefanie Arndt, CC-BY 4.0)
The research vessel Polarstern in the Arctic. (© Alfred Wegener Institute / Stefanie Arndt, CC-BY 4.0)

Mar­ine sed­i­ments cover more than two thirds of our plan­et’s sur­face. Nev­er­the­less, they are scarcely ex­plored, es­pe­cially in the deeper re­gions of the oceans. For their nu­tri­tion, the bac­teria in the deep ocean are al­most en­tirely de­pend­ent on rem­nants of or­gan­isms that trickle down from the up­per wa­ter lay­ers. De­pend­ing on how they pro­cess this ma­ter­ial, it either re­mains in the depths of the ocean for a long time or moves back to the sur­face as car­bon di­ox­ide. Thus, sea-floor bac­teria play an im­port­ant role in the global car­bon cycle, which makes them an ex­cit­ing and im­port­ant re­search ob­ject.

Global play­ers at the sea­floor

The “Benthic Microbiology”-team on Polarstern expedition PS85 to the Arctic long-term observatory HAUSGARTEN. Josephine Rapp (far left), Christina Bienhold (second from right) and Katy Hoffmann (far right) are co-authors of the study, Stefan Becker (second from left) supported the sampling. (© S. Becker)
The “Benthic Microbiology”-team on Polarstern expedition PS85 to the Arctic long-term observatory HAUSGARTEN. Josephine Rapp (far left), Christina Bienhold (second from right) and Katy Hoffmann (far right) are co-authors of the study, Stefan Becker (second from left) supported the sampling. (© S. Becker)

The re­search team around Christina Bi­en­hold and Katy Hoff­mann from the Max Planck In­sti­tute in Bre­men and Pierre Of­fre, who now works at the NIOZ on the is­land of Texel, has now iden­ti­fied and char­ac­ter­ised a par­tic­u­larly dom­in­ant group of mi­crobes. “Al­though these bac­teria have been known in the lit­er­at­ure for some time,” Bi­en­hold ex­plains, “nobody has paid much at­ten­tion to them un­til now.” While the team fo­cused on the role of this group in the deep sea, other re­search­ers at the Max Planck In­sti­tute for Mar­ine Mi­cro­bi­o­logy in­vest­ig­ated its im­port­ance in coastal sed­i­ments. “Only now does it be­come clear how nu­mer­ous and wide­spread mem­bers of Woeseiales are,” Bi­en­hold con­tin­ues.

An im­press­ive 40 mil­lion cells in­habit each mil­li­litre of deep-sea floor – to­gether with a bil­lion other bac­teria. In a thimble full of sed­i­ment, there are thus about 120 mil­lion cells of Woeseiales. “We know of no other group of bac­teria that oc­curs in the ocean floor at such high abund­ances.“ Ex­tra­pol­ated to the en­tire deep-sea floor, the world­wide pop­u­la­tion of Woeseiales would amount to 5 x 1026 cells, the au­thors es­tim­ate. “Con­sid­er­ing that these es­tim­ates in­clude neither the coastal sed­i­ments nor the deep bio­sphere, these bac­teria may be one of the most com­mon groups of mi­croor­gan­isms on Earth,” ex­plains Bi­en­hold.

A group with var­ied eco­lo­gical roles

In their study, the au­thors present an eco­lo­gical syn­thesis sum­mar­ising cur­rent know­ledge about the di­versity and en­vir­on­mental dis­tri­bu­tion of these bac­teria. The syn­thesis was built upon DNA se­quence data, which were de­pos­ited in pub­lic data­bases over the last two dec­ades, but also in­cluded new data, some of which was gen­er­ated from arc­tic deep-sea sed­i­ments col­lec­ted at the AWI-main­tained long-term observatory HAUSGARTEN. “The ana­lyses re­veal that Woeseiales ac­com­mod­ate a myriad of or­gan­isms with var­ied eco­lo­gies,” ex­plains Pierre Of­fre, lead au­thor of the study. “For ex­ample, dif­fer­ent spe­cies of Woeseiales co-ex­ist to­gether at any loc­a­tion of the seabed, where they prob­ably ful­fil dif­fer­ent eco­lo­gical func­tions. Our study provides a first eco­lo­gical guide to these fas­cin­at­ing or­gan­isms.”

Moreover, the data now avail­able in­dic­ate that mem­bers of Woeseiales could feed on so-called pro­tein­aceous mat­ter, such as the re­mains of cell walls and mem­branes or other leftovers of dead or­gan­isms. Con­sid­er­ing that pro­teins are a ma­jor source of ni­tro­gen ­– a fun­da­mental nu­tri­ent for all life forms – in mar­ine sea­floor sed­i­ments, the po­ten­tial abil­ity of Woeseiales bac­teria for pro­tein de­grad­a­tion, may be eco­lo­gic­ally im­port­ant for the re-cyc­ling of ni­tro­gen in benthic eco­sys­tems.“ I am con­vinced that fur­ther stud­ies of these bac­teria will provide new in­sights into the car­bon and ni­tro­gen cycles in mar­ine sed­i­ments,” con­cludes Of­fre, who con­tin­ues in­vest­ig­at­ing these mi­croor­gan­isms to un­der­stand the secret of their eco­lo­gical suc­cess, to­gether with his re­search team at NIOZ.

Tiefsee-Meeresboden am Langzeitobservatorium HAUSGARTEN in der Arktis. Die Aufnahme entstand mit dem „Ocean Floor Observation System“ des Alfred-Wegener-Instituts. (© OFOS, Alfred Wegener Institute)
Tiefsee-Meeresboden am Langzeitobservatorium HAUSGARTEN in der Arktis. Die Aufnahme entstand mit dem „Ocean Floor Observation System“ des Alfred-Wegener-Instituts. (© OFOS, Alfred Wegener Institute)

Behind the paper: Read more about the work be­hind this pu­bli­ca­ti­on in the cor­re­spon­ding blog­post by Chris­ti­na Bi­en­hold and Pier­re Off­re: https://naturemicrobiologycommunity.nature.com/users/348350-pierre-offre/posts/59450-spotlight-on-woeseiales-bacteria-cosmopolitan-denizens-of-marine-sediments

The re­sults pre­sen­ted here were ob­tai­ned wi­t­hin the frame­work of the re­se­arch pro­ject ABYSS hea­ded by Ant­je Boe­ti­us, group lea­der at the Max Planck In­sti­tu­te for Ma­ri­ne Mi­cro­bio­lo­gy and di­rec­tor at the Al­fred We­ge­ner In­sti­tu­te Helm­holtz Cent­re for Po­lar and Ma­ri­ne Re­se­arch, which was fun­ded by the Eu­ro­pean Re­se­arch Com­mis­si­on bet­ween 2012 and 2018.

Fur­ther in­for­ma­ti­on on ABYSS can be found here: https://erc.europa.eu/projects-figures/stories/life-deep-microbes-abyss

 

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Par­ti­cip­at­ing in­sti­tu­tions

Please dir­ect your quer­ies to:

Scientist

HGF MPG Joint Research Group for Deep-Sea Ecology and Technology

Dr. Christina Bienhold

MPI for Marine Microbiology
Celsiusstr. 1
D-28359 Bremen
Germany

Room: 

1336

Phone: 

+49 421 2028-8690

Dr. Christina Bienhold

NIOZ Royal Netherlands Institute for Sea Research

De­part­ment of Mar­ine Mi­cro­bi­o­logy and Biogeo­chem­istry, and Utrecht Uni­versity, Den Burg, The Neth­er­lands

Dr. Pierre Offre

Phone:  +31 (0)222 369 489

E-Mail: Pierre.Of­fre@nioz.nl

Head of Press & Communications

Dr. Fanni Aspetsberger

MPI for Marine Microbiology
Celsiusstr. 1
D-28359 Bremen
Germany

Room: 

1345

Phone: 

+49 421 2028-9470

Dr. Fanni Aspetsberger
 
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