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Dissolved inorganic carbon fixation of Thaumarchaeota vs. Bacteria in the meso- and
upper bathypelagic waters of the world´s oceans differenciated with the use of metabolic inhibitors
Marta M. Varela, Gerhard Herndl, Eva Sintes, Eva Teira, & Josep Gasol
Instituto Español de Oceanografía-IEO. CO-CoruñaUniversidade de VienaUniversidade de Vigo.
Institut de Ciències del Mar. CMIMA , CSIC
Recent studies suggest that unidentified prokaryotes fix inorganic carbon at significant rates in the dark ocean (Reinthaler et al. 2010; Varela et al. 2011)
Genomic and physiological studies have shown evidences that Thaumarchaeota should play an important role in the carbon cycle (Herndl et al. 2005; Walker et al. 2010)
0 10 20 30 40 50
Subsurface
upper O2-min
lower O2-min
MSOW
AAIW
upperNEADW
lowerNEADW
DI14C-positive cells in percent
0 10 20 30 40 50
Subsurface
upper O2-min
lower O2-min
MSOW
AAIW
upperNEADW
lowerNEADW
Wat
er M
ass
DI14C-positive cells in percent
Picoplankton
Bacteria
Crenarchaeota
eastern-Atlantic mid-Atlantic
WHY?
Some Bacteria showed high chemoautotrophic activityAlonso-Sáez et al. 2010, Varela et al. 2011)
Global ocean prokaryotic community composition:
Major groups of prokaryotes: Bacteria, Eury- and ThaumarchaeotaBacteria: SAR 11, SAR202, Alteromonas, SAR 406, SAR324
Global ocean and deep water bulk uptake of bicarbonate, differentiating Bacteria and Thaumarchaeota contribution (Yokokawa et al.
Single-cell identification of active dark bicarbonate fixers
To examine the contribution of Thaumarchaeota vs. Bacteria to total prokaryotic fixation of dissolved inorganic carbon (DIC) in the meso- and upper batypelagic waters of the world oceans.
GOAL OF THE STUDY:
Radiolabeled Substrate
(14C)
Incubation
Fixation &Filtration Radioactive
cell
Non-Radioactive cell
target
probe
Prokaryotic community composition: by Fluorescence In Situ Hybridization (CARD-FISH):
HOW ?
Group Specific Activity: by microautoradiography combined with FISH (MICRO-CARD-FISH)
Dissolved inorganic carbon (DIC) fixation: incorporation of 14C-bicarbonate, by using Erythromycin to discriminate archaeal from bacterial activity (Yokokawa et al. 2012)
Bicarbonate assimilation
MICRO-CARD-FISH
Malaspina 2010 Circumnavigation Expedition: Global Change and Biodiversity Exploration of the Global Ocean" (December 2010-July 2011)
STUDY SITE
150º 100º 50º 0º 50º 100º 150º
50º
0º
50º
4652 57 60 66
8689
93
98105 110 116
124130132135138
143
E EWWW 0
N
S
EQ
E 8000
6000
4000
2000
0
2000
4000
6000
8000
0
Pacific Ocean
AtlanticOcean
Indian Ocean
Indian Ocean: 46; 52; 57; 60; 66
Pacific Ocean: 86; 89; 93; 98; 105; 110; 116; 124
Atlantic Ocean: 130; 132; 135; 138; 143
Bacteria vs. Eury- and Thaumarchaeota + cells (% of DAPI counts):
WHAT ?
Indian Ocean Pacific Ocean Atlantic Ocean
n=9 n=
61%11%2%
26%
55%
12%3%
30%
n= 4
Mes
opel
agic
Bath
ypel
agic
61%16%
6%
17%
67%
26%
1%
6%
SAR11, SAR 202, Alteromonas, SAR 406, SAR 324 + cells (% of Eub + cell):
Indian Ocean Pacific Ocean Atlantic Ocean
n= 11
16%5%
3%
10%
8%
58%
Mes
opel
agic
n= 4
19%
9%
10%
9%10%
43%
Bath
ypel
agic
n=9
24%
3%
16%
21%
7%
29%
30%
12%
19%
18%
3%18%
n= 13
DIC fixation by the prokaryotic community(bulk uptake of 14C-bicarbonate):
0
200
400
600
800
1000
1200
1400
1600
0.00 0.01 0.10 1.00 10.00 100.00
control
Erythromycin
0.00 0.01 0.10 1.00 10.00 100.00
control
Erythromycin
0.00 0.01 0.10 1.00 10.00 100.00
control
Erythromycin
De
pth
(m
)
DI14C fixation (µmol C m-3 d-1)
Indian Ocean Pacific Ocean Atlantic Ocean
Contribution of Bacteria vs. Thaumarchaeota to DIC fixation :
0
200
400
600
800
1000
1200
1400
1600
0 20 40 60 80 100D
epth
(m
)Contribution to DI14C incorporation rate (%)
Bacteria Thaumarchaeota
Bacteria ThaumarchaeotaBacteria Thaumarchaeota
Indian OceanPacific OceanAtlantic Ocean
% of Bacteria or Thaumarchaeota incorporating bicarbonate:
SUMMARY Bacteria dominated throughout the water column in the three world oceans (54% of the total DAPI counts) and did not change with depth.By contrast, the abundance of Cren was generally higher in the bathypelagic layers than in the mesopelagic waters (reaching values up to 29% of the total DAPI counts in the Pacific Ocean).
SAR11 contributed 8, 33 and 18% to total prokaryotic inorganic carbon incorporation in the Indian, Pacific and Atlantic world oceans, respectively, over the entire water column.
Archaea contributed 8, 33 and 18% to total prokaryotic inorganic carbon incorporation in the Indian, Pacific and Atlantic world oceans, respectively, over the entire water column.
The Archaea contribution to total prokaryotic carbon incorporation tends to increases with depth, particularly at the Atlantic waters below 1000m and in the lower mesopelagic zone of the Pacific Ocean.
Single-cell analysis
We thank all the people involved in the MALASPINA 2010 project who helped with the cruise preparation and sampling.
ACKNOWLEDGMENTS
· We also thank the officers and crew of the R/V Hespérides, as well as the staff of the Technical Support Unit (UTM), for their support during the work at sea.
·This research was supported contracts MALASPINA (CSD 2008-00077), BIO-PROF and MODUPLAN.