短鎖炭化水素の海洋硫酸塩還元細菌による無酸素酸化
Olaf Kniemeyer1, Florin Musat, Stefan M Sievert
1Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, D-28359 Bremen, Germany.
Nature
|September 21, 2007
まとめ
硫酸塩還元細菌 (SRB) は,プロパンとブタンを唯一のエネルギー源として使用して培養することができます. これらの無酸素細菌は,海洋環境における短鎖炭化水素の生物分解を証明し,ガス組成と硫化物産生に影響を与えています.
科学分野:
- 微生物学 微生物学とは
- 環境科学 環境科学
- 地質化学 地質化学
背景:
- 短い鎖の炭化水素 (エタン,プロパン,ブタン) は通常,熱化学的に導出されますが,生物学的に形成されることがあります.
- これらの炭化水素の微生物利用は,有酸素細菌で知られているが,無酸素経路はあまり理解されていない.
- 以前の観測では,無酸素で炭化水素が豊富な環境で,短鎖炭化水素の"in situ"生物分解が示唆されていた.
研究 の 目的:
- 短鎖炭化水素の無酸素微生物利用を調査する.
- プロパンとブタンを代謝できる硫酸塩還元細菌 (SRB) を濃縮して分離する.
- これらの炭化水素を分解するSRBの代謝経路と系統遺伝的属性を特徴づける.
主な方法:
- 様々な温度 (12,28,60°C) でプロパンまたはn-ブタンをソール基板として使用して,海洋炭化水素の浸透堆積物からSRBを濃縮する.
- 菌株BuS5を含む純粋な培養物の分離と,その基質利用範囲のテスト.
- 炭化水素酸化産物の分析,代謝物質の識別 (例えば,サクシネート誘導体),および16SリボソームRNA遺伝子配列の解析.
主要な成果:
- プロパンとn-ブータンを利用したSRB培養物の成功濃縮,一部の培養物は残留堆積物なしで育つ.
- プロパンとn-ブタンを特異的に消費したメソフィルの純粋培養 (株BuS5) の分離.
- CO2への完全な炭化水素酸化の実証と,13C濃縮アルケンの優先分解の証拠を伴うフーマレートを含む新しいアルケンの活性化経路の特定.
結論:
- 多様な海洋のSRBは,浸透地域やガス貯蔵庫などの無酸素環境でプロパンとブタンを成長基材として効果的に利用できます.
- この微生物の活動は,天然ガスの組成の変化と硫化物の生成に貢献します.
- この発見は,無酸素炭化水素の生物分解経路と炭化水素豊富な生態系におけるSRBの生態学的役割に関する新しい洞察を明らかにします.
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