PNAS：一种极端厌氧菌基因组测序完成

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PNAS：一种极端厌氧菌基因组测序完成


  生物谷报道：Syntrophus aciditrophicus是一种极端厌氧菌，用以维持生命的食物非常简单，是为数不多的能够降解有机物脂肪酸的生命形式，在全球碳循环中发挥关键作用。最近加州大学洛杉矶分校的研究人员完成了其基因组测序工作，共鉴别出3169个基因。

  大多数生命利用氧降解有机物获得能量，反应过程中产生的电子驱动储存能量的ATP生成。Syntrophus是极端厌氧菌，不能进行氧化作用，其电子流动方向与氧化作用中的电子传递方向相反，反应耗能、产生氢和甲酸盐（formate）。因此如果没有消耗氢和甲酸盐、产能的其它细菌帮助，Syntrophus不能生存。

  Robert Gunsalus小组鉴别出几个Syntrophus参与反向电子转移（耗能）的基因，他们进一步打算研究这种机制。“如果我们能够弄清这种‘互养共栖新陈代谢’，也许就能提高从废物中获取的氢量，实现生物氢生产。”详细研究内容刊登于《PNAS》（DOI: 10.1073/pnas.0610456104）

英文原文：

Extreme-living bacteria has genome sequenced
22:00 16 April 2007
NewScientist.com news service
Rowan Hooper
The bacterium Syntrophus aciditrophicus, one of the most extreme-survival organisms ever discovered, has had its genome sequenced.

Syntrophus lives on a diet so austere that it exists on the brink of energetic death. The genes now discovered making up its genome are providing clues as to how it survives, and might even improve the efficiency by which we can make hydrogen from waste materials, the researchers say.

Robert Gunsalus at the University of California, Los Angeles, US, and colleagues, identified 3169 genes in Syntrophus. The bacterium performs a key part of the global carbon cycle by breaking down fatty acids in organic matter – a very limited diet consumed by almost no other organisms. To do this it needs genes that can participate in thermodynamically unfavourable reactions known as reverse electron transport.

Most organisms use oxygen to help breakdown organic compounds for energy use. In this process, organic compounds are chemically oxidised, and the electrons produced in the reaction are used to drive the production of the energy-storage compound ATP.

Syntrophus lives in an anaerobic (non-oxygen) environment, where such a key reaction is impossible. Instead, the flow of electrons occurs in the opposite direction – reverse electron transport – through a reaction that produces hydrogen and formate, which actually requires energy. Without the \"help\" of other types of bacteria, which consume the hydrogen and formate and provide energy in return, Syntrophus could not survive.

Gunsalus's team found several genes that appear to participate in this process, and they hope to gain a better understanding of the mechanism. “If we can understand such 'syntrophic metabolism', we may be able to increase the amount of hydrogen that can be made from waste materials, and hopefully make biohydrogen production a reality,” says Gunsalus.

Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0610456104)