Bacterial morphologies in carbonaceous meteorites and comet - PowerPoint Presentation

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Bacterial morphologies in carbonaceous meteorites and comet dust

Chandra

Wickramasinghe

1

,

Max K.

Wallis

1

,

Carl H. Gibson

2

, Jamie

Wallis

1

,

Shirwan

Al-Mufti

1

&

Nori

Miyake

1

1

Cardiff Centre for Astrobiology, Cardiff University, UK.

2

Depts

of Mechanical and Aerospace Engineering and Scripps Institution of Oceanography,

Center

for Astrophysics and Space Sciences,  University of California at San Diego, La Jolla CA 92093-0411, USA

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To re-visit evidence for microbial fossils in carbonaceous chondrites

, linking with extensive modern evidence of Richard Hoover

Examine progress from Claus and Nagy, via Hans Pflug, to Richard Hoover and colleaguesTo examine data for IDP’s in relation to embedded particles and organicsDiscuss presence of acritarchs in cryosampler collections of cometary dustDiscuss relevance to cometary panspermia and cosmology

AimsSlide3

Early History of MicrofossilsEarly in the 1960’s, Claus and Nagy (1961) identified possible microfossils in carbonaceous chondrites (CCs), supported by chemical bio-markersThese were refuted vigorously on grounds of contamination and the subject fell into disrepute – some ragweed pollen but possibly small component

In the 1980’s the matter was re-opened by Hans Dieter

Pflug using modern techniquesSlide4

Pflug prepared ultra-thin sections (< 1mm) of the Murchison meteorite

H.D.Pflug

The sections were placed on membrane filters and exposed to hydrofluoric acid vapour. In situ demineralisation was achieved leaving carbonaceous structures indigenous to the meteorite in tact. A wealth of morphologies revealed. Slide5
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Structures resembling the influenza virusSlide8

Laser ion probe showed biomarkers within the microfossilsSlide9

Richard Hoover has found a wealth of microfossil structures with biomarkers + low N that leaves no room for dispute.. Slide10

This is consistent with the distribution of biologically relevant molecules discovered in the Murchison meteorite by Schmidt-Koplin et al (2010) Slide11

If comets carriers of microbial life, a diversity of organic molecules as rich, or richer the terrestrial set is expected.Slide12

Water-ice and organics

found in

Tempel 13 areas less than 0.5% of surface, 1.5 & 2µm ice bands

Ice?

Ice could be

surfaces

of

lakes exposed by

impacts – and organics in plentySlide13

+ Clay - evidence

of liquid water in

cometsSlide14

Primordial radiogenic heating, with 26

Al decays for comets forming 1My after incorporation of

26Al Heat transfer calculations show melting for comets with radii in excess of 10km, with substantial volume fractions staying melted for periods of a fraction of My at leastPossibility of liquid water predicted theoreticallySlide15

Conclusions so far...Carbonaceous meteorites carry microfossils of living organismsThey are most likely relic comets that had liquid interior regionsCometary pools sites for microbial replication?

Theories of

cometary panspermia strongly supported by this dataImplication is that injection of microbes from comets is an ongoing processSlide16

Dust from modern cometsThe Earth picks up debris from comets in the present dayCollection of comet dust in the atmosphere could provide additional proof of cometary life

Daily arrival rate 60 tonnesSlide17

Brownlee particles – collected from 1970’sAgglomeration of comet dust

18 micrometres

Similar to terrestrial fossil of iron-oxidising bacteriumSlide18

Cyrosampler collections, from 2001 (ISRO)Aseptic collectionLow relative velocity preserves fragile structuresSearches for viable microbes + fossil microbes possibleRisk of contamination can be minimised/avoided by going to sufficient heightsSlide19

Stratospheric balloon with

cryosampler

probes launched from Hyderabad on 20 January 2001Slide20

Each probe consists of a

fully sterilised

, evacuated stainless steel cylinder, of volume 0.35 litreDuring flight the cylinders are immersed in liquid Ne, cooled to 25o K, thus producing a powerful cryopump.Over a hundred STP litres of air (and aerosols) in the height range 25-41 km is sucked in and frozen in situWhen brought to ground level and room temperature, the air pressure ~ 200 barsCollected air released through filters to trap aerosolsSlide21

A wide range of particles from comets identifiedSizes from 0.1 – 10 µmMineral condensate mixed with carbonaceous material – possible nanobacteria, spores and fossil microbes

C ~ 20%, O – 36%

Fe – 33%, low N+ Na + Ca + PSlide22

Acritarchs on EarthOrganic-walled microfossils found in sedimentary unidentified species

Present in sediments from 3.2Gy agoSlide23

Acritarchs in meteoritesRossignol-Strick

+

Barghoorn 1971 – revisited 2005 acid macerated extract of the Orgueil CC meteoritespherical hollow microstructures = well-defined wallsMukhopadhyay, + SPIE 2009Murchison SEM – part mineralisedSulphur mapSlide24

Achritarchs in cryoprobe sample2009

About 9~10

µm diam. spheres- Carbonaceous, often cracked, with cracks opening under the SEM heatingLower image has fossilised flagella-whiskersThe carbon fraction ~ 60% also oxidised (O ~ 12%, N ~1%) Coating is mainly Na and Cl .. also some S, Si and K (< 1%)Slide25

Pair of 2.5-3 m acritarchs with intriguing coatings.

Very high C (58%)Slide26

Example of ~10m spherical particles + mineral coatingV

ery

high in C (70%) Consistently low NSlide27

Possible

acritarchs

occur abundantly in comet dust collectionSlide28

‘Grapes’ rich in C, O, Na, Fe and P.

Silicate whisker =

3 μm in length‘CHO’ umbrella+S1+S2S3+Slide29

Cracked shells and whiskersSlide30
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Silica whiskers are abundantFirst thought to be contaminantNow found to be integral to acritarchs Slide32
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Torroidal particles, with cracked shellsSlide34
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Diatoms most likely explanationSlide38

Evidence of diatom silica in astronomical sources go back to work of Hoover et al, 1984

Here the points are data for IR emission in the Trapezium nebula and the curve is for a mixed culture of diatoms Slide39

Only 10% mass

from

crystalline olivine is requiredDiatom silica is consistent with comet spectraComet Hale-Bopp at 2.9 AU observed on 6-10-1996 Mix of olivine at temperature 175K and material resembling biomaterial including diatoms at 200KSlide40

We conclude with the intriguing possibility of living bacteria being included among the acritarchs

Samples are treated with

carbocyanine dyes showing viable and dead cells.Viable (Green) and dead (Red) fluorescent stained bodies (bacteria) are obtained from air sampled at a height of 30-39kmSlide41

Other bacteria detected by stainsSlide42

Coccoidal forms in SEM – living bacteriaSlide43

New work confirm thqt living bacteria are included in comet dust

More recently….Slide44

Concluding....According to our favoured theory of cometary panspermia, living forms of the shapes we have seen were locked in frozen planets 10 million years after the Big Bang

The mass of each planet has a CNO content estimated to be ~ 10

27 g. The ingress of a single such planet into the pre-solar nebula provides material for 1011 Oort-cloud cometsSlide45

Evidence of a disintegrating planet in the Helix Nebula provides striking evidence of such a process in action