New research from Monash University and the University of Queensland has added a new dimension to understanding life on the Red Planet with the discovery that meteorites may be able to ‘trap’ evidence of extraterrestrial life.
This image shows Watson 021, a single H7 ordinary chondrite, weighing 135 g. The sample has a large crack, lined with alteration minerals, that runs down its middle and only one third of its fusion crust remains intact. This meteorite shows near complete oxidation of its reduced metal and sulfide phases making this a W4 chondrite. Watson 021 is extensively shocked, exhibiting globular silicate metal emulsions and shock veins that crosscut the sample. Tait et al found that microbial communities in samples of Nullarbor Plain soil are more diverse than those in Watson 021 and other meteorites, which are highly uniform in their species evenness and species richness. Image credit: Tait et al, doi: 10.3389/fmicb.2017.01227.
“Most work on meteorites and life is concerned with two areas of research,” explained lead author Dr. Alastair Tait, of Monash University.
“Panspermia, the idea that life is carried inside debris blasted off a fertile planet by giant impacts, and travels through space to land on a dead planet, thus colonizing it.”
“Or a pre-biotic pantry delivering all the right ingredients to kick start the origin of life.”
“Our theory adds a third avenue of research, which is the interaction between astro-materials and an existing biosphere,” he added.
“This is a brand new field that has not been looked at before.”
Dr. Tait and co-authors were able to show that the chemical composition of rocks influences how microbial communities develop by studying bacteria and Archaea in meteorites collected from the Nullarbor Plain, a 20-million year old and 200,000 sq.km area dominated by limestone karst that spans the southern regions of South and Western Australia.
“We conducted 16S rRNA gene analysis on chondritic meteorites (Watson 019-022) and soil from the Nullarbor Plain,” the researchers said.
“We found that the meteorites have low species richness and evenness compared to soil sampled from directly beneath each meteorite.”
“Despite the meteorites being found miles apart, the community structure of each meteorite bore more similarity to those of other meteorites than to the community structure of the soil on which it resided.”
The meteorites were dominated by sequences that affiliated with Actinobacteria. Proteobacteria and Bacteroidetes were the next most abundant groups.
The soils were also dominated by Actinobacteria but to a lesser extent than the meteorites.
“Our results show that microorganisms can interact with astro-materials in a way that is vital to their metabolism,” Dr. Tait said.
The findings were published recently in the journal Frontiers in Microbiology and are part of a broader research project on using biomarkers in meteorites as a means to detect life throughout the Solar System.
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Alastair W. Tait et al. Microbial Populations of Stony Meteorites: Substrate Controls on First Colonizers. Front. Microbiol, published online June 30, 2017; doi: 10.3389/fmicb.2017.01227
This article is based on text provided by Monash University.
