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hello my name is gabriel gonzalf silva

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and i'm going to present my current work

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called biogenicity influences in

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iron ii bearing minerals by extremely

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acidophilic bacterium

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acetobacillus feroxides this work was

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developed

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in the chemistry laboratory at the

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campus institute of the university of

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sao paulo brazil

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so let's begin in this work

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we used the microorganism acetobacillus

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peroxidants

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a chemical trophic bacterium that is

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able to gain

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energy from the oxidation of inorganic

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substances

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in this case it can use the oxidation of

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iron and sulfur

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and the energy produced is used to fix

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carbon dioxide for the production of

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biomass

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all of this can happen in a very acidic

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environments

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with a ph as low as 1.8

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we choose to use two minerals on this

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study

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city right and visionite sterite is an

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iron carbonate can be used as source of

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energy

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to the presence of iron to iron

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and carbonate that can be used as a

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source of carbon for biomass production

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for the microorganism

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this mineral was already confirmed on

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mars

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vivianite is an iron phosphate it can be

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used as a source of energy for the

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microorganism

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and is also a source of phosphorus

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among the many elements used by life

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phosphorus is the less common boat on

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mars

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and on earth the presence of this

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mineral was

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not confirmed on mars but it's possible

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that it can be found

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on phosphorus-rich patches found on the

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planet

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on earth both minerals can be found

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associated with life

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for example both minerals are already

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found in

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different kinds of fossils after the

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microorganism grows we look for signals

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of

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bacteria activity in the minerals to

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differentiate physical and chemical

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alterations from biological

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modifications

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we use the biogenesis criteria to

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identify the

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so-called biosignatures those build

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signatures can be mechanical

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like the disruption of the mineral

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grains or biochemical

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these include productions of

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nanocoatings from for example

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the position of eps extracellular

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polymeric substance

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that after drying can form desiccation

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cracks

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other biochemical signatures include

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micro topographic

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changes like beating itching information

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of path

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by moving cells enhancing enhancing

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dissolution of the minerals and

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production

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or precipitation of secondary minerals

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the study of possible few signatures in

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rocks and minerals in a martian contest

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is recent very important work published

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in 2021 used a thermoacetophilic

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organism called methylospherocetal

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growing over a martian meteorite but

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focuses in the formation of

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intracellular vulneralization and other

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molecular build signatures

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our work started with the first

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investigation of the growth passage

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basils for accidents on city right in

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vivianite

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the very first results of this work were

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present in the last upgrade cone

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by our colleague roberto vicenzi and now

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the manuscript

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is in the last stages of preparation

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so what is our goal in this work

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in this study we evaluated different

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biogenicity criteria

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as biomechanical and biochemical changes

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abused signatures on the minerals

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ciliarite

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and vivianite exposed to an acidic

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medium

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in different conditions as abiotic and

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biotic

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with the presence of the microorganism

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as a type of cells

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for oxidants to do so

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we use the following in the futures we

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use the

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lr strain of the stubacious feroxides

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growing the modified tnk medium

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with the addition of the mineral as the

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only source of energy for the organism

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the creatures were made in two

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conditions biotic

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and abiotic as a control always in a ph

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of about 1.8

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at 30 degrees in the incubator shaker

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table

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at 180 rpm for each future

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it was added about five millimole of

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community and shifted scissorid or

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vivianite

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the analytical methods employed to stir

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the minerals were

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sim scanning electron microscope

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ids energy dispersive x-ray spectroscopy

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rayman and xrd the x-ray diffraction

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so these are the results we obtained

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first the citrite on the left one can

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see

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an sim image of a typical grain of the

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mineral before the experiment

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a large piece is covered by smaller and

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sharper grains

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broken during the mineral grinding

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unfortunately

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this is right was almost completely

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dissolved in the apic acid

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however on the right one can see the

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result of the

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biotic assay on the first victory

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we can see a formation of paths left by

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the cells they have a richer signature

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in carbon

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showing red probably by the position of

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the eps

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the second picture one can see the

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desiccated eps forming contractions

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cracks

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the mineral is under the eps and can be

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reorganized by the presence of magnesium

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show it in yellow or the eps

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are amorphous grains probably

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schwarzmanite

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a bureau precipitate formed from the

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iron iii

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produced by the microorganism the last

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picture

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gives a better perspective of the

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desiccated eps chlorine acetylene grain

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the vivian knight shows a similar

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pattern in this case we have on the left

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the result of

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abiotic attack on the vivianite again

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one can see sharp pieces of mineral

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while on the right

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the biotic experiments produced eps

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curved grains

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with contractions cracks once again

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it was found around amorphous minerals

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curving

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the vivianite however this time their

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composition wasn't compatible with the

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mineral schwarzmanite

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using raymond we compared our pure

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vivianite market sv with the vivianite

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left

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after the abiotic antibiotic experiments

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respectively market as va and vb

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we also use the data from the literature

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for mere vivianite

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a natural slightly oxidized fibunite

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phase

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whose peaks are market as mv and pure

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vivianite

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market as v-star we also collected data

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for santa barbarite

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an amorphous iron iii phosphate

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considered a completely oxidized phase

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of the vivianite

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our initial vivianite shows some peaks

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of both vivianite

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and metavivianite but both

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biotic and abiotic show it some decrease

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of amorphous phases

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similar to the center barbarite

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to better evaluate the hypothesis of the

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formation of a sentence barbarity in the

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cultures

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we made a xrd with our pure vivianite

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a pure sample of santa barbarite and the

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material left after the abiotic and

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biarch

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cultures the graphic a shows again that

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our initial material is a mixture of

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vivianite with metavivianite

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the graphic b shows a highly amount of

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santa barbarite

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the graphic c shows some degree of

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amorphism

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but the vivianite peaks are strong and

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easily identifiable in the abiotic

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sample

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is highly amorphous show a good

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similarity

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to the center barbaric cooperating with

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the idea

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that the microorganism induces the

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formation of santa barbarite as

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the bioprecipitation instead of the

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schwarzmanite

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so to conclude first

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we were able to identify many biogenic

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criteria in our mineral samples

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to be used as biosignatures of the

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growth of the association basil's for

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oxidants

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these blue signatures can be used while

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looking for old life signals

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both on mars and on earth also

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we have strong evidence of the

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production of center barbarite a

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biomineral that

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unlikely survives menite was never

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described but for creatures of

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satubacious fluorescence

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these and other discoveries will be

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included in another manuscript that is

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also in preparation

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open questions and future work this work

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opens paths for mark questions that

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could be addressed

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are there other biogenic mineral phases

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that could be found on mars

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what other minerals can be a source of

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iron too from microorganisms like

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accidents for accidents in a martian

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contest

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how these new signatures could be

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affected in a more complex context

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like in the presence of brains and the

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ancient mars

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also to complete this work we need to

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find the definitive identification

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of the phosphor bearing amorphous

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mineral phase

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found in the biotic creatures of

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vivianite

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it is it really sunset barbarite

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we also want to do more research to

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better understand the development of

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these signatures of

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iron ii bare minerals mix it with

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different kinds of sediments

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and last we need more research of the

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view signatures of iron to bearing rocks

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as models of martian lithologies like

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for example

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the use of more complex rocks like

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basalt

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to finish i'd like to thank all the

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collaborators and colleagues that helped

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within this study

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and the agencies that contributed to

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have the work done

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please feel free to contact me with

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questions