Team:Tokyo Tech/Iron-oxidizing bacteria

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Contents

Achievement

  • We cultured iron-oxidizing bacteria (Acidithiobacillus ferrooidans).
change of the color of 9K medium

Introduciton ~Why do we need to use Iron-oxidizing bacteria for terraforming of Mars?~

Heterotrophic bacteria cannot live in native Martian environment because there are no organic matters on the Martian surface, however autotrophic bacteria can live without organic matters.
Iron-oxidizing bacteria is autotrophic bacteria.
Iron-oxidizing bacteria get energy by oxidizing Fe(Ⅱ) and grow with CO2. To grow on Mars, iron-oxidizing bacteria require only energy injection of us because of composition of the Martian surface, crust and atmosphere.
Martian surface and crust contains FeO(Fe(Ⅱ)) and carbonate.In addition, Martian atmosphere contains much CO2.(detail リンク)
We propose culturing iron-oxidizing bacteria on Mars to produce organic matters.
Accumulation of organic matters provides habitable environment for heterotrophic bacteria (for instance, E.coli).
We plan to culture iron-oxidizing bacteria on the Martian surface in early stage of terraforming to accumulate enough organic matters for heterotrophic bacteria to live.

Material and method

Iron-oxidizing bacteria

Iron-oxidizing bacterium is a kind of autotrophic bacteria.
Iron-oxidizing bacteria reduce NAD+ to NADH by oxidizing Fe(Ⅱ).
Iron-oxidizing bacteria grow with dissolved CO2 as carbon source, not organic matters.
In laboratory, iron-oxidizing bacteria are cultured in 9K medium which contains Fe(Ⅱ) and no organic matters.

Preparation of 9K medium (for iron-oxidizing bacteria)

We Prepared following A and B solution.

A Solution
B Solution

We sterilized A solution by autoclaving. We sterilizde B solution by using filter.
We Mixed A and B solution before use.

Cultivation of Acidithiobacillus ferrooxidans

We cultured in 9K medium at 30℃ with vigorous shaking. We used the microscope when confirmed the growth.

Result

Cultivation of A.ferrooxidans

change of the color of 9K medium

We cultured Acidithiobacillus ferrooxidans (iron-oxidizing bacteria).
The medium for A.ferrooxidans was blue before cultivation owing to Fe(Ⅱ).
The presence of A.ferrooxidans changed the medium into brown one after culturing for two days.
We confirmed the growth by using microscope of 200 magnifications.

This experiment was conducted by Shinya Tahara (student member).





Discussion

To apply to terraforming of Mars, we have to introduce genes to iron-oxidizing bacteria. There are few methods for selecting iron-oxidizing bacteria with introduced genes, because antibiotics deactivate in culture conditions of iron-oxidizing bacteria. Some researchers succeeded in introducing genes to iron-oxidizing bacteria in the previous researches. They introduced mercury-resistance gene to iron-oxidizing bacteria and selected in the medium that contains mercury ion.

Reference

  • TOMONOBU KUSANO, KAZUYUKI SUGAWARA, CHIHIRO INOUE, TOSHIYUKI TAKESHIMA, MASAHIKO NUMATA, AND TOSHIKAZU SHIRATORI2 (1992) Electrotransformation of Thiobacillus ferrooxidans with Plasmids Containing a mer Determinant JOURNAL OF BACTERIOLOGY, Oct. 1992, p. 6617-6623
  • MEDIA FOORMULATIONS http://wdcm.nig.ac.jp/catalogue/ncim/document/Ncim_media.pdf
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