の代わりにヒ素を用いて増殖できる細菌
Felisa Wolfe-Simon1, Jodi Switzer Blum, Thomas R Kulp
1NASA Astrobiology Institute, USA. felisawolfesimon@gmail.com
まとめ
ある種のバクテリアは,生命にとって不可欠な元素であるリンを,ヒ素に置き換えることができる. モノ・レイクバクテリアのこの発見は,代替的な生化学が存在し,生命の進化に関する私たちの理解に影響を与える可能性があることを示唆しています.
科学分野:
- 天体生物学 アストロバイオロジー
- バイオケミストリー バイオケミストリー
- 地質化学 地質化学
背景:
- 生命は主に炭素,水素,窒素,酸素,硫黄,リン (CHNOPS) の6つの元素を使用しています.
- これらの元素は,核酸,タンパク質,脂質のような必須のマクロモレキュルを形成します.
- 同様の生物学的役割を持つ代替元素の可能性は,科学的な調査の分野であり続けています.
研究 の 目的:
- 生物が主要なバイオエレメントを周期表の他の生物で置き換えることができるかどうかを調査する.
- 成長のために代替要素を利用できるバクテリアを特定し,特徴づけること.
- アルセニックが重要なバイオ分子でリンを代用できるかどうかを判断する.
主な方法:
- カリフォルニア州モノ湖からバクテリアの分離と培養.
- フォスファートとアルセネートの濃度が異なる媒介を用いた成長実験.
- 質量スペクトロメトリーなどのテクニックを用いて細胞マクロ分子を分析し,元素の組成を検出する.
主要な成果:
- 菌株GFAJ-1 (Halomonadaceae) というバクテリアがモノ湖から分離されました.
- 菌株GFAJ-1は,アルセネートと限られたリン酸塩の存在で成長を示した.
- 証拠によると,アルセネートは核酸やタンパク質に組み込まれ,リン酸を代用している.
結論:
- バクテリアGFAJ-1は,重要な生物分子のリンをヒ素に置き換えることができる.
- この発見は,生命における代替的生化学の可能性を示している.
- 主要なバイオエレメントを代用する能力は,進化論と地化学の研究に大きな意味を持っています.
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