Isolation, Characterization, and Ecology
of Cold-Active, Chemolithotrophic,
Sulfur-Oxidizing Bacteria from
Perennially Ice-Covered Lake Fryxell,
Antarctica
W. Matthew Sattley and Michael T. Madigan
Southern Illinois University
Robert Simmon, NASA
McMurdo Dry Valley
Dale Anderson, ASLO,Feb ‘06
Illustration By:
Jon W. Olson, PhD
Sept ‘06
Dale Anderson, ASLO,Feb ‘06
CANADIAN GLACIER
80 ft ice wall
LAKE FRYXELL
Joe Mastroianni, National Science Foundation, December 10 2002
Lake Fryxell Stats
• 18 meters deep (6 meters of ice)
• Physically stable water column = highly
stratified
– Salinity Gradient 0-0.8% NaCl
– Supersaturated O2 below ice to anoxic near
sediment
• Little water input from Canadian Glacier
– Only 2mm annual precipitation
• Nowhere to go (little evaporation)
• Strictly microbial biota
METHODS
1. Drill
2. Collect
Joel Moore, ASLO, Sept ‘04
3. Measure:
-O2
-Temp
-Sulfate
-Sulfide
Madigan group ‘03
Thiobacillus strain FTL9
Thiobacillus thioparus
Small cocci to short rod, motile, gram negative
Arrows point to elemental sulfur globules. Accumulate as
thiosulfate is oxidized.
1
2
1. Scanning electron micrograph of FTL9--different stages of
growth
2. Transmission electron micrograph of FTL9--longitudinal and
cross-sectioned cells. Arrows point to polyhedral
carboxysomes (contain Calvin Cycle enzymes)
Rice fields
groundH20
cave
Phylogenetic tree generated from 16S rRNA gene
FTL = Fryxell Thiobacillus-like
Physiology Fun Facts of FTL
• Unable to utilize organics = Obligate
Chemolithoautotrophs
• Electron donors
– Thiosulfate S2O32– Sulfide
– Elemental Sulfur S0
– Thiocyanate SCN-
♥Who loves Physiology?♥
• pH
– T. thioparus - pH range 5-9 (optimum 7)
– FTL9 - pH range 6.5-9.5 (optimum 7.75-8)
– FTL10/11 - pH range 6.25-9.5 (optimum 7.75-8)
• Salt Concentrations (no requirement)
– T. thioparus - Inhibited growth > 1.3% NaCl
– FTL9 - concentrations up to 2.4% NaCl
– FTL10/11 - concentrations up to 2.6% NaCl
• Temperature...
Closed circles = FTL9
Open circles = T. thioparus
Big Picture...
THE SULFUR CYCLE
S0
S2O32Chemoautotrophs
(ex. FTL)
SO42Sulfate reducers
(ex. Desulfovibrio)
oxic
H2S
anoxic
Productive Lake
•
•
•
•
•
Sulfur cycle
Oxygen photosynthesis
Anoxygenic photosynthesis
Methanogenesis
Homoacetogenesis
Conclusions
• FTL (compared to T. thioparus)
– Higher salt tolerance
– Cold adaptation
– Acid pH intolerance
• Closes Sulfur Cycle (provides sulfate)
• Supplies much needed organic carbon
QUESTIONS??
How is it surviving anoxic conditions? Is it metabolically active?