Magnetofossils are 'compelling' evidence of Martian life


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<!--intro-->An Iowa State University professor is part of a research team that has found compelling evidence that Mars once supported primitive life. The researchers discovered evidence of bacteria in a Martian meteorite. Tiny magnetite crystals -- so called magnetofossils -- embedded in the meteorite were confirmed to be the type produced only by a biological process unique to magnetotactic bacteria. <!--/intro-->

Dennis Bazylinski, associate professor of microbiology, was one of nine researchers conducting the four-year investigation, which was funded by NASA's Astrobiology Institute. A <a HREF="">report of their research</a> is in the December issue of the scientific journal, "Geochimica et Cosmochimica Acta."

"Finding these type of magnetic crystals in any material from another planet is an amazing and important finding," said Bazylinski. He leads one of the few labs capable of culturing these magnet-producing bacteria, which are common in many freshwater and marine environments on Earth.

The researchers studied the magnetite crystals that were located in carbonates in the Martian meteorite. The 4.5 billion year-old meteorite was found in Antarctica in 1984. Earlier research has confirmed that the carbonates formed on Mars, signaling that the magnetite crystals also were formed on Mars.

Magnetite crystals produced by magnetotactic bacteria are chemically pure and generally defect free and have a distinctive size and shape. Their properties are so unusual that they have only been seen in magnetite crystals produced through biological processes by organisms.

The researchers discovered that about one-fourth of the magnetites in the meteorite are identical to the magnetites produced by a strain of magnetotactic bacteria called MV-1, which have been isolated and studied extensively by Bazylinski.

"There is currently no known chemical means of producing these magnetite crystals with their unique morphologies," Bazylinski said. "The significance to astrobiology and geobiology is that many scientists have been searching for 'biomarkers' for life, that is, chemical, isotopic, and/or mineral indications that life was present, either in extreme habitats or in ancient materials on Earth and, of course, now in extraterrestrial materials. The need for biomarkers is obvious and these magnetite crystals might prove to be an excellent biomarker."

Since the team began the research in 1996, observations from the Mars Global Surveyor have indicated that Mars had a strong magnetic field at about time that the carbonate containing the unique magnetites was formed.

"Now we are trying to answer the question of whether magnetotactic bacteria could have actually lived on Mars," Bazylinski said. "And we have found certain aspects of their metabolism which suggest that they might have been able to do so."

The journal "Science" recently published research showing evidence of widespread sediment layers on Mars, which the researchers interpret to be the product of many lakes. Because these lakes may have provided a habitat for magnetotactic bacteria, this finding supports the possibility that the bacteria may have existed on Mars, Bazylinski said.

In addition to Bazylinski, the scientists are Kathie Thomas-Keprta, Simon Clemett, and Susan Wentworth, Lockheed Martin at Johnson Space Center; David McKay and Everett Gibson, NASA/JSC; Joseph Kirschvink, California Institute of Technology; H. Vali, McGill University, Montreal; and Christopher Romanek, Savannah River Ecology Laboratory.