大気中の微量ガスは,南極の砂漠の表面土壌における一次生産を支えている
Mukan Ji1, Chris Greening2, Inka Vanwonterghem3
1School of Biotechnology and Biomolecular Sciences, Australian Centre for Astrobiology, UNSW Sydney, Randwick, New South Wales 2052, Australia.
Nature
|December 7, 2017
まとめ
南極の砂漠の土壌の微生物コミュニティは 水素や一酸化炭素のような大気中の微量ガスで繁栄しています これらのガスは 太陽光や地質学的な源から独立して 生命を支える 重要なエネルギーと炭素を供給します
科学分野:
- 微生物学
- 天体生物学
- 環境科学
背景:
- 南極の砂漠の土壌は 豊かな微生物の棲み家ですが 光合成能力が低いコミュニティの エネルギー源は不明です
- これらのエネルギー経路を理解することは オリゴトロフィック環境における 生命の限界を理解するために 極めて重要です
研究 の 目的:
- 南極の土壌微生物コミュニティの主要なエネルギー源としての大気微量ガスの役割を調査する.
- これらのガスを利用する代謝経路と生物を特定する.
主な方法:
- 候補属 WPS-2 と AD3 を含むメタゲノムデータから 23 件のゲノム草案を再構築.
- ガス代謝に関与する重要な酵素 (水酸化物,一酸化炭素脱水酸化物,RuBisCO) の遺伝子発現の分析
- 大気中のH2とCOとCO2の固定を測定するために,土壌のマイクロコスムを育成する.
主要な成果:
- 主要な微生物群は,化学合成炭素固定のためのRuBisCO系統とともに,高親和性水酸化物および一酸化炭素脱水酸化物の遺伝子を持っています.
- 理論上のエネルギー維持を支える速度で大気中のH2とCOをエロビックスキャビングすることが示されました.
- 重要な化学二酸化炭素の固定が観察され,光合成の固定は無視される.
結論:
- 大気中のH2,CO,CO2は,南極の土壌微生物コミュニティをサポートする信頼できるエネルギーと炭素源として提案されています.
- 太陽光や地質学的なエネルギー源に代わる 潜在的エネルギー源として 強調しています
- この発見は 生命の最低限の栄養要求と 他の惑星での生命の可能性について 洞察力を与えてくれます
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