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DHABs: extreme environments

Bacterial communities in the seawater-brine chemocline in deep anoxic hypersaline basins (DHABs) in the eastern Mediterranean Sea Borin S., Daffonchio D., Brusa T., Gasparoni F.,Calore D., Corselli C., and BIODEEP Scientific Team 1 University of Milan, DISTAM, Via Celoria 2, 20133 Milan, Italy

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DHABs: extreme environments

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  1. Bacterial communities in the seawater-brine chemocline in deep anoxic hypersaline basins (DHABs) in the eastern Mediterranean Sea Borin S., Daffonchio D., Brusa T., Gasparoni F.,Calore D., Corselli C., and BIODEEP Scientific Team 1University of Milan, DISTAM, Via Celoria 2, 20133 Milan, Italy 2Tecnomare s.p.a., San Marco 3584, 30124 Venice, Italy 3University of Milan-Bicocca, DGSG, P.zza della Scienza 4, 20126 Milan, Italy

  2. DHABs: extreme environments Bannock Urania L’Atalante Discovery 3200-3700 m deep • Absence of light • High pressure • Anoxic High salinity (>30%) • High density: no mix with overlaying sea water • Very old origin (Messinian evaporites dissolution) Steep chemocline (O2, H2S, salinity) at the sea water/brine interface • Do microbes inhabit DHABs?

  3. BIODEEP project BIOtechnologies from the DEEP Urania L’Atalante Discovery Bannock • BIODEEP cruises • R/V URANIA • August 2001 • June 2002

  4. DAPI cell counts cells/ml of sample W 1500m L’Atalante Discovery Bannock Urania 2,8 104 W 2500m Water column 1500m 4,3 104 2500m W 3300m 3,9 104 2,3 104 3300m Water/brines interface 6,1 105 3,4 106 1,2 106 1 106 WB 1,9 104 1,5 105 7,8 104 4,7 104 brines B 3500m

  5. Typing of Eubacteria and Archaea in DHABs RISA eubacteria ARDRA eubacteria DGGE archaea interface interface interface interface interface interface interface interface brines interfaces brine brine brine brine brine A B U D U U A A B D B A U D B A U basin

  6. Peculiar communities inhabit DHABs Urania Discovery Principal Component Analysis of eubacterial community RISA profiles I I L’Atalante B B I B Bannock PC 2 (10% of the variability) I Upper seawater column PC 1 (29,5% of the variability)

  7. Sea water/brines interfaces act as “particle traps” and are an enrichment phase for bacteria • Study of the chemocline • Community fingerprinting • DAPI counts • Total DNA quantification • Real time PCR Prokariotes and Archaea

  8. R/V Urania MODUS Accurate chemocline sampling Biodeep cruise, august 2001 Deep Sea SciPack DHABs S/W interface Sea floor Remote operated MODUS/SCIPACK system developed to collect water and brine samples with an accurate depth and position control in the DHABs environment.

  9. Conductivity vs. depth: Urania sea water/brine interface Brines CTD recovery Conductivity (salinity) CTD deployment Seawater 3521.5m 3523.5m

  10. 10L Niskin bottle n°3 10L Niskin bottle n°4 Closure of Niskin bottles vs. depth WATER URANIA INTERFACE depth BRINES

  11. 10th litre …. Brine 4th litre 3 1 2 4 5 10 2 6 1 9 7 8 10 L Niskin bottle 3 3rd litre 4 5 6 7 Sea water conductivity 8 10 9 2nd litre 1st litre Niskin 3 Niskin 4 HS- (mmoles/l) Density (g/l) The chemocline Urania basin Bannock basin DNA extraction and microbial community molecular characterisation

  12. Water/brine interface: eubacterial diversity along the salinity gradient Niskin 3 Niskin 4 Salinity: 3.7% Salinity: 5.1% Salinity: 5.7% Salinity: 9.1% Salinity: 16.1% ARISA eubacteria ARDRA eubacteria New bands Disappearing bands Using sensitive techniques such as ARISA some population shifts are observed

  13. Along the salinity gradient are there quantitative differences among microbialpopulations? B2 B1 URANIA INTERFACE DAPI cells counts and DNA extraction yields • TaqMan Real time PCR targeting 16S rDNA: • universal for prokariotes • universal for archaea

  14. Bacteria in the DHABs chemoclines Chemoclines at the sea water/brine interfaces act as particle trap Microbial communities in the different DHABs are very diverse Microbial community in the chemocline at the sea water/brine interface is different from the brine and the upper sea water Diversity shifts can be observed along the chemocline of Urania basin Sea water/brine interface seems an enrichment phase especially for Eubacteria

  15. BIODEEP project BIOtechnologies from the DEEP funded by the European Union Marine Science and Technology programme Fifth Framework Programme http://www.geo.unimib.it/BioDeep/Project.html Thanks to: the scientific and technical staff, and the crew of the Urania oceanographic ship.

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