Title: MICROBIAL MATS IN ANTARCTICA AS MODELS FOR THE SEARCH OF LIFE ON EUROPA
1MICROBIAL MATS IN ANTARCTICA AS MODELS FOR THE
SEARCH OF LIFE ON EUROPA
- Suman Dudeja
- (Senior Lecturer)
- A.R. S. D. College,South campus
- University of Delhi
- sdudeja.arsd_at_du.ac.in, dudejasuman_at_gmail.com
2- SUMAN DUDEJA
- ARANYA B. BHATTACHERJEE
- AND
- JULIAN CHELA-FLORES
- Associate ICTP
- Max Planck InstituteÂ
- fur Physik Komplexer Systeme,Â
Nothnitzer Str. 38, 01187 Dresden,Germany - The Abdus Salam International Centre for
Theoretical Physics, Trieste, Italy and Instituto
de Estudios Avanzados, Caracas 1015A, Venezuela. - Permanent Institute Department of Physics and
Chemistry, A.R.S.D College, University of Delhi,
South Campus, - Dhaula Kuan, New Delhi-110021, India.
3Out line of talk
- Motivation
- Life in extreme Environments
- Microbial mats
- Antarctica Sub glacial Lakes I/II
- Europa and Laplace mission
- Conclusions
4Motivation
- Observation of Europa by Galilean spacecraft.
- Possibility of a warm ocean under the ice crust.
- Possible existence of extra-terrestrial
biological activity as Sulfur patches are found. - Anaerobes living in extreme environments found in
sub glacial lakes in Antarctica.
5Life In Extreme Environments
- Extremophiles microorganisms not only tolerate
harsh environments but thrive in them. - Examples
- Thermophiles surviving in higher temp. till
74-114ÂşC. - Psychrophiles are able to grow at -20ÂşC found in
Antarctica - Halophiles tolerating salt concentration up to
saturation. - Acidophiles live at pH as low as 0.5.
- Alkalipihiles can survive till pH10-14.
- Bacterium D. Radiourans can withstand ionizing
radiations ( up to 20kGy of ?- radiation) and UV
radiations (upto 1000Jm-2). - The Extreme environments and their microbes
living in Mirobial Mats can thus act as models
for extraterrestrial life.
Rothschild L. J. and Mancinelli R. L.(2001) Life
in extreme environments Nature, 409, 1092
Seckbach J., Oren A. and Chela-Flores, J. (sep
2008). European Planetary Science Congress in
MĂĽnster Germany. Seckbach, J. and Chela-Flores,
J. (2007)., in Hoover, R.B., Levin, G.V.,
Rozanov, A.Y. and Davies, P.C.W. (eds.),
Instruments, Methods, and Missions for
Astrobiology X. Proceedings of SPIE Vol. 6694,
66940W
6Relevance of Microbial Mats in Astrobiology
7Microbial mats on surface of some lakes
- The mat has patches of white, yellow, and dark
brown areascolonised by different groups of
microorganisms, such as sulfur-oxidizers,
sulfate-reducers, methanogens, and - other heterotrophs. Â
What are sulfate reducers?
8Sulfate Reducing Bacteria (SRB)as transport
agents
Under anaerobic conditions, sulfate is used by
bacteria as an electron acceptor for oxidation of
organic carbon by following reaction, called as
sulphate respiration or Dissimilatory bacterial
sulfate eduction, (SRB/BSR) 2ltCH2Ogt SO42-(aq)Â
2H(aq)Â ? CO2(g)H2S(g)Â 2H2O (e- donor) The
isotope 32S increases in product H2S and thereby
reduced in SO42-. Presence of organic carbon
increases the rate of SRB. What is the source of
organic carbon? EPS (Exocellular Polymeric
Substance A metabolic product of microbes)
Biochemical sulfur cycle in a sedimentary
ecosystems with oxic/anoxic zones (Guerrero et.
al, 2002) thesis Alvarez (2005)
Jorgenson B. B. (1982a),. Nature, 296, 643-645
and (1982b),. Phill. Trans. R. Soc. Lond. B 298,
543-562. Rabus et al., (2006) The Prokaryotes,
Spinger, v2, p 659-768.
9Antarcticas Subglacial Lakes and Mirobial Mats
- Part-I
- Perennially ice covered Lakes-Location
- Dry valley Lakes/McMudro Lakes
- Wright Valley/Victoria Valley/Taylor Valley lakes
- Lake Boney/Lake Fryxel /Lake Chad// Lake Hoare
- Lift-Off Microbial mats
10Antarctica
11Antarctica-Where are Dry Valleys?
How they are formed ?
12McMudro Dry Valley Areas (Antarctica)
13Taylor Valley Lakes Fly-over
14 Data of 4 of the 20 lakes of the McMurdo Dry
Valleys, Antarctica
__________________________________________________
__________________________________________________
________________
Lake Maximum depth, m Elevation, m ( above sea level) Lake type Microbial Mats
__________________________________________________
____________________
Lake Chad (Taylor Valley) 1.0 58 Perennial ice cover liquid water MM, ICM, FM, CLM, PRM
Lake Fryxell (Taylor Valley) 18 17 Perennial ice cover liquid water MM, ICM, FM, CLM, APRM, ANPRM
Lake Hoare (Taylor Valley) 34 73 Perennial ice cover liquid water, MM, ICM, FM, CLM, APRM, ANPRM
Lake Vanda (Wright Valley) 69 123 Perennial ice cover liquid water PM, APRM
__________________________________________________
__________________
15Lake Hoare
Lake Hoare
                                             Lake Hoare from the North Shorewith Canada Glacier in the background
Lake Hoare
                                             Lake Hoare from the North Shorewith Canada Glacier in the background
from the North Shore
Lake Hoare Ice - 2005
                  Â
2006
Microbial mats in Lake Hoare (top view)
16Antarctica's perennially ice-covered Lake Hoare
with sand and microbial mats (FM ICM) surface
down into the ice. Soil blows onto the lake from
a nearby dry valley, warms in the sun, and melts
downward, leaving a bubble column in its trail.
17Estimated annual removal of selected chemical
constituents (Kg) by escaping algal mats in
lakes Chad, Hoare and Fryxell, Antarctica.
Chad Hoare Fryxell Organic
matter 8343.0 247.0 1450.0 Ca 279.5 105.9
552.1 Fe 352.3 76.6 309.5 S 104.0
56.0 40.1 Na 49.4 18.6 147.4 Cl 9.2
4.6 419.4 Parker et al. J. Phycol. Vol. 18,
72, (1982)
18Benthic microbial mat community in Lake Hoare A
Bottom View
Underwater beneath the 4.5 meter thick ice-cover
of Lake Hoare, looking back at the dive hole.
.
19Prostate microbial mats in lake Hoare at 8m
water depth
Pinacles (APRM) appearing (magnified)
Smooth-flattened (ANPRM)
Pinnacle mat (PM) morphology
20Microbial Lift-Off (CLM)Mats in Antarctica dry
valley lakes
- Benthic microbial mat in Lake Bonney. Gas buildup
can cause mats tolift-off the bottom and
sometimes tear loose and float up to the bottom
of the ice cover in Antarctica dry valley lakes
SCUBA diver collecting sediment cores from Lake
Hoare in Taylor Valley.
21Microbial community
Schematic representation of a cyanobacterial
microbial mat with associated depth-related
light and chemical gradients.
22Antarctica-How dry valleys form?
Antarctica-Dry valley areas
- Are the dry valley lakes microbial mats
again present or in stage of evolution at - Lake Vostok ? and
- may harbour life at Europa?
23Antarcticas Subglacial Lakes Part-II
- Lake Vostok
- Location
- Unexplored Lake beneath
- 4km ice cover
- Microbes found in 3.7km
- Harboring hydrothermal vents
Nature Siegert et al., 2001, 414(6) 603 Jouzel
et al, 1999, Kapista et al., 1996, 381,
684, Priscu J. C. et al., Science, 1999, 286,
2141 Doran et. al., 1998
24Antarctica subglacial lakes
Overview of Antarctica with Lake Vostok
25Aerogeophysical data collected on a grid of
flight lines can be used to map Lake Vostok
The left image shows the ice surface.
On the right, you can
"see" through the ice. The image shows the
rocks outside the lake (brown colors) and the
lake surface beneath 4 km of ice (blue colors).
26Digging across accreted (melted and refrozen) ice
in Lake Vostok
Mirobes found throughout 3.7km ice cover
of Lake Vostok
3540 m Interface
Environmental Microbiol., 3, 570-577, 2001
27- Thus, Lake Vostok
- Appears to harbor hydrothermal vents beneath
the water surface. - Geothermal heating will warm the bottom water.
- Leading to vertical convective circulation in
the lake - This warming of water appears to be responsible
for supporting microbial growth in lake, as
samples of accreted ice (melted and refrozen ice)
are detected to contain many microbes.
Proteobacteria having lineage to SRB - Suggestive of, what may be occurring on Europa
- Ice cores drilled into ice of Antarctica exhibit
the presence of mirobial life at all levels. - Shen Y. et. Al., Earth Sci. Rev., (2004) 64,
342-272.
28Overview of Jupiters Moon Europa Quick-Look
Statistics
Discovery Jan 7, 1610 by Galileo Galilei
NASAS missions Voyager (1975-76), Cassini
(2000), Galileo (1995-2003) Diameter (km) 3,138
Mean Distance from Jupiter (km) 670,900
Surface Composition Water Ice
29Photos taken by the Galileo spacecraft, Nov 1998.
A small region of disrupted ice crust
False-color image reddish brown ridges and
terrain indicate the presence of contaminants in
the icy Europan surface
Double ridges, dark spots, and smooth icy plains
Greenberg R. Europa- The occean Moon, Springer
, 2005
30Evidence of Mercaptans on Europa
Near Infra-red Mapping Spectrometer (NIMS)
Experiment by Galileo
3.88 micro-meter absorption line
Attributed to S-H bond of Mercaptans
T.B. McCord et. al., Jour. Geochem. Res. Vol.
103, N0. E4, pp. 8603 (1998).
31EUROPAS CROSS SECTION
WATER
Silicate
Fe
ICE
32How can an icy-moon EUROPA be habitable?
- Presence of liquid water ?
- Adequate energy source to sustain necessary
metabolic reactions ? - A source of chemical elements (C,N,H,P,O,S) ?
- Relevant pressure and temperature conditions ?
- Induced magnetic field measured by Galileo
mission- PUTATIVE EXISTANCE OF OCEAN BENEATH ICE
CRUST - High level of radiation on Europa's surface may
provide storage of chemical free energy SOURCE
IN IRRADIATION PRODUCTS - By recent models, liquid water is in contact with
silicate core- FAVORABLE FOR PROVIDING VARIETY OF
CHEMICALS - Interactions in ocean and silicate core, can be
the cause of HYDROTHERMAL ACTIVITY
Plot of biosignatures as a function of Depth
33Laplace Resonance keeps the orbital periods of
IO, Europa and Ganeymade in the ratio of 124.
Orbital energy gained by IO due to tidal torques
exerted by Jupiter is distributed among 3 moons
locked in LR. This resonance is essential for
ongoing tidal heating inside Europa and may allow
for the existence of an ocean inside Europa over
billion of years.
34The question of origin of Sulfur?
- Ions implanted from the Jovian plasma.
- Sulfurous material may be of geologic origin (
Carlson et. al. Science, vol.286 (1999). - Accumulated effect of biogenic process over
geologic time.
35Parameters for biogenic Sulfur
- Delta Sulfur parameter (d xS)
- Isotope fractionation factor
- Temperature
36SIGNIFICANCE OF DELTA SULFUR (d xS) PARAMETER
Where, x  33, 34 or 36
Standard troilite of the CanonÂ
Diablo meteorite (CDM)
Metabolic pathways of sulfur bacteria have enzyme
s that preferentially select  the isotope 32S
 over 34S. This implies that where there is an ab
undance of sulfur bacteria, the value of  d34SÂ
would be negative.
37 Effect of Temperature
- The magnitude of isotope fractionation xa ,
- by microbial sulfate reduction also dependsÂ
upon temperature - Â
Canfield D.E. , Olesen C.A. and Cox R.P. (2006)
Temperature and its control of isotope
fractionation by a sulfate reducing bacterium,.
) Geochimica Cosmochimica Acta,  70, 548-561
38Isotope fractionation as a function of temperature
39SULFURÂ IONÂ IMPLANTATIONÂ ONÂ THEÂ SURFACEÂ OFÂ EUROPA
- Sulfur of biogenic origin if present on the
surface of Europa is contaminated by energetic
sulfur ions from Jovian atmosphere. - d34S value changes from its biological value due
to contamination. - Future probe to Europa has to go beyond theÂ
maximum stopping  depth of the sulfur ions - (4.810-5cm)  to measure  d34S of biogenic
origin.
40Figure 2 Density distribution of sulphur ions n(x
) (atoms/cm3) implanted from the Jovian atmosphere
 as a function of dimensional depth (x/Rp)
for t  106 years , ? 9.0 106(cm 2 -s)-1 and
 Rp 4.8 10-5 cm. The maximum density is at th
e range x  Rp. The distribution is GaussianÂ
Graph based on the LSS(Lindhard, Scharff an
d Schiøt) theory of ion implantation
41Major Questions
- How biological processes would effect measurable
and observable quantities? - What is the best way to detect them?
- Drop penetrating probes and in situ Chemical
and Physical laboratory (CPL). - Scan the surface for a window to the underlying
ocean.
42A proposed future mission for Jupiter and its
Moons
What should characterizemicro-penetrators
? Very low mass projectiles (c.f. Lunar A
13.5Kg DS-2 3.6Kg) High impact
speed Penetrate surface few metres Perform
initial important science on planetary surface
(2015-2025)
Blanc M. et al., Geopyical Research Abstracts,
vol10, EGU2008.
43Europa Penetrators
- Low mass projectiles 4KgPDS
-
- High impact speed 200-500 m/s
- Very tough 10-50kgee
- Penetrate surface 0.5-few metres
- Perform science from below surface
Low mass projectiles 4KgPDS High impact
speed 200-500 m/s Very tough
10-50kg Penetrate surface 0.5-few
metres Perform science from below surface
44Conclusions
- The experience with sub glacial lakes of
Antarctica especially presence of Microbial mats
at extreme environments is relevant for the
exploration of the Solar system. - In the Solar System, Europa is the best candidate
for the search of life outside the Earth. - Our calculations are in (IC/2008/34, and in
Microbial Mats (Springer to be submitted by
invitation) - These arguments suggest that with LAPLACE
equipped with penetrators, only a penetration of
a few millimeters would be sufficient for
deciding on biogenicity.
45AND SEARCH BEGINS
ALL TRUTHS ARE EASY TO UNDERSTAND ONCE THEY ARE
DISCOVERED THE POINT IS TO DISCOVER THEM -
GALILEO GALILEI
dudejasuman_at_gmail.com , suman_dudeja_at_yahoo.co.in,
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47- Oceans verifying their existence, finding their
locations, studying the structure of their icy
crusts, and assessing active internal processes - Astrobiology determining the types of volatiles
and organics on and near the surfaces, and the
processes involved in their formation and
modification - Jovian System Interactions studying the
atmospheres of the satellites and the
interactions among Jupiter and the surfaces and
interiors of the satellites
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49Effect of Temperature
- The magnitude of isotope fractionation
by microbial sulphate reduction also dependsÂ
upon temperatureÂ
The isotope fractionation factor at equilibrium ca
n be derived from the ratios of theÂ
partition function (Q),Â
50The partition function is derived
Q Â
Where,Â
ui
h is the Planck constant, k is the Boltzman consta
nt, T is the temperature in Kelvin andÂ
 is the ?th vibrational frequency of the molecule)
 .
51Based on the LSS(Lindhard, Scharff and Schiøt) the
ory of ion implantation, the implant profile in an
 amorphous material canbe described
by the equation (Sze, S. M.1988)Â
(7) Where,Â
Where,Â
,
  is the implanted dose, t is the time of implanta
tion, Rp is the projection range and is equal to
the average distance an ion travels before it
stops and ?Rp is the standard deviation of Rp whic
h is roughly 1/5Rp from the known  data forÂ
different ions and impact surface. The value of Rp
 for sulfur ion for the Europan surface  is
4.810-5cm and ? 9.0 106 (cm2 -s)-1
,
 Â
52Graphs based on the LSS(Lindhard, Scharff and Schi
øt) theory of ion implantation
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