?生物谷報(bào)道：古生菌最早于上世紀(jì)70年代末被發(fā)現(xiàn)，它們是生命樹的3大主要分支之一,，另外兩種是細(xì)菌及真核生物（包括植物和動(dòng)物）,。但是科學(xué)家知道最近才從生態(tài)角度了解古生菌的生存機(jī)制,。
??由Georgia大學(xué)科學(xué)家領(lǐng)導(dǎo)的小組在本周三Toronto舉行的美國(guó)微生物學(xué)會(huì)會(huì)議上宣布，一種生活在熱泉系統(tǒng)的古生菌種類——泉古菌（crenarchaeota）——利用氨作為它們的能量來(lái)源,。文章的第一作者,，UGA的Savannah River生態(tài)實(shí)驗(yàn)室科學(xué)家Chuanlun Zhang表示，這種代謝模式此前從未在其它高溫古生菌中發(fā)現(xiàn)過(guò),。
??Zhang說(shuō)：“此前我們并不認(rèn)為氨的氧化是泉古菌中起支配作用的過(guò)程,，但是現(xiàn)在我們意識(shí)到了它的重要性。”Zhang還是海洋學(xué)的副教授,，他的合作者來(lái)自Nevada大學(xué),、Montana州立大學(xué)、Savannah River國(guó)家實(shí)驗(yàn)室,、哈佛大學(xué)等,。
??Zhang和同事從美國(guó)、中國(guó),、俄羅斯的熱泉系統(tǒng)中取樣,，結(jié)果發(fā)現(xiàn)一種amoA基因廣泛存在，微生物用它們將氨和氧結(jié)合,，然后放出能量,。此前其它小組利用DNA技術(shù)證明泉古菌能將環(huán)境中的氨轉(zhuǎn)化。Zhang認(rèn)為這一發(fā)現(xiàn)顯示了泉古菌在極端環(huán)境下的生態(tài)作用,。
??由于這類古生菌生活在類似于原始地球環(huán)境的熱泉中,，因此Zhang表示它們將幫助科學(xué)家更好的了解地球生命的早期進(jìn)化過(guò)程。他說(shuō)：“如果想了解生物和它們的代謝過(guò)程的進(jìn)化,，我們就需要同時(shí)了解熱泉環(huán)境和低溫環(huán)境,。因此泉古菌對(duì)于我們很重要，它們?cè)谶@兩種環(huán)境中都能很好的生存,。”
英文原文：
http://www.physorg.com/news99134279.html
Published: 10:17 EST, May 23, 2007
Study reveals function of ubiquitous yet poorly understood microorganisms
Discovered in the late 1970s, archaea are one of the three main branches on the tree of life, with bacteria and eukaryotes such as plants and animals on the other two branches. But scientists are just now gaining a fuller understanding of what archaea do – in an ecological sense – to make a living.
A new study led by University of Georgia researchers and announced on Wednesday at the American Society for Microbiology meeting in Toronto finds that crenarchaeota, one of the most common groups of archaea and a group that includes members that live in hot springs, use ammonia as their energy source. Chuanlun Zhang, lead author of the study and associate research scientist at UGA’s Savannah River Ecology Laboratory, said such a metabolic mode has not been found in any of the other known high-temperature archaea.
"The oxidation of ammonia was not thought to be a dominant process for crenarchaeota, but now we realize how important it is," said Zhang, who is also associate professor of marine sciences. His co-authors include researchers from the University of Nevada Las Vegas, Montana State University, Savannah River National Laboratory, Harvard University and Yunnan University in China.
Zhang and his colleagues (Christopher Bagwell, SRNL; Brian Hedlund, UNLV; Bill Inskeep, MSU; WenJun Li, Yunnan University; Ann Pearson, Harvard; Christopher Romanek and Juergen Wiegel, UGA) sampled extensively from hot springs in the United States, China and Russia for crenarchaeota and found the widespread distribution of the presumed amoA genes, which microorganisms use to combine ammonia with oxygen, releasing useable energy. Previous studies by other teams used a DNA-based forensic ecology approach to suggest crenarchaeota’s role in converting ammonia in mundane environments such as sea water, soil and even waste treatment plants. Zhang said the results of this latest comprehensive study give a picture of the ecological role of crenarchaeota in more extreme environments such as the hot springs.
Because ammonia-oxidizing archaea are associated with a group of microorganisms that thrive in hot spring environments that are thought to resemble early conditions on Earth, Zhang said they may help scientists better understand the earliest stages of evolution on the planet.
"If we want to know how organisms evolved and how their metabolism evolved, we need to understand both the hot springs environment and the low-temperature environment," said Zhang. "Crenarchaeota are special because they thrive in both environments."
Source: University of Georgia
