在海洋微生物的舞臺上,，有這么一群生活在“遺失之城”和海底火山口附近的微生物，它們數(shù)量稀少,，充當(dāng)著“候補(bǔ)演員”的角色,，并且時刻準(zhǔn)備著代替那些“主角”微生物，躍升為“海洋微生物之星”,。
據(jù)華盛頓大學(xué)發(fā)表的研究報告來看,，上述現(xiàn)象正出現(xiàn)在中大西洋“遺失之城”和深?；鹕絿娍趨^(qū)域。該區(qū)域是至今為止在中大西洋發(fā)現(xiàn)的唯一一處火山噴口區(qū),。這些較活躍的微生物位于一個火山口附近,。該火山口已有1000多年歷史，由于其噴液逐漸緩和并冷卻,，改變了周圍的生態(tài)系統(tǒng),。
華盛頓大學(xué)博士后威廉姆·布拉澤爾頓(William Brazelton)表示，這些生物的發(fā)現(xiàn)首次證明微生物能夠很長的一段時間都保持著較少的數(shù)量,，然而一旦生態(tài)系統(tǒng)發(fā)生變化,，它們就能從數(shù)量上完全扭轉(zhuǎn)形勢占據(jù)優(yōu)勢地位。這種說法看起來具有邏輯性,，然而至今為止,，科學(xué)家們卻還是不能探測到族群數(shù)量如此稀少的微生物。
此外,，科學(xué)家們還發(fā)現(xiàn),，這些生活在海底火山口附近的微生物的種類超乎人們的想象。使用最新的DNA測序技術(shù),，結(jié)果顯示海洋中存在的微生物種類可能比此前預(yù)測的數(shù)目多過十至一百倍,。特別是位于“遺失之城”的海域，這些微生物的種類甚至都無法鑒別出來,，有些微生物的種類此前根本沒有發(fā)現(xiàn)過,，即使發(fā)現(xiàn)了的新物種，種群數(shù)量也是少的驚人,。
2000年,，美國國家科學(xué)基金會(National Science Foundation)的海洋生物教授黛博拉·凱樂（Deborah Kelley）與她的同事們發(fā)現(xiàn)了“遺失之城”。他們乘坐亞特蘭蒂斯號船進(jìn)行探索,，這也是此區(qū)域名為“遺失之城”的原因之一,。不同形式的熱溫泉從含有豐富的金屬，溫度高達(dá)700華氏度（約371.11攝氏度）的黑色煙囪噴口處涌出,。“遺失之城”噴出的海水溫達(dá)200華氏度（約93.33攝氏度）或低于,，與石灰?guī)r洞穴同樣材料的純碳酸鹽附近是噴口區(qū)以及其他結(jié)構(gòu)。噴口處的海水具有高堿性并且含有豐富的甲烷和氫氣,，是“遺失之城”中微生物生存的重要能源,。
科學(xué)家們在“遺失之城”進(jìn)行了大量的季節(jié)性的短期研究。布拉澤爾頓及其同事通過分析發(fā)現(xiàn),，在“遺失之城”30000年的生命歷程中,，微生物的主宰過程在循環(huán)發(fā)生。因此,，出現(xiàn)的適應(yīng)了生存環(huán)境的微生物們?nèi)栽诘却m合它們的生態(tài)系統(tǒng),。“遺失之城”的罕見生物圈是微生物經(jīng)歷了長期的環(huán)境變化的儲存庫,。隨著稀有生物的出現(xiàn)，之所以它們能夠快速的發(fā)展新的利基,，是因?yàn)樗麄兲崆斑x擇了與過去相同的條件來生存,。
科學(xué)家表示，從過去幾千年在“遺失之城”的生態(tài)環(huán)境多次轉(zhuǎn)變來看,，這些稀有生物體與占據(jù)主要地位的生物體有著密切相關(guān)的聯(lián)系,，它們是實(shí)實(shí)在在的生物，能歷經(jīng)微妙的變化繁衍后代,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS January 11, 2010, doi: 10.1073/pnas.0905369107
Archaea and bacteria with surprising microdiversity show shifts in dominance over 1,000-year time scales in hydrothermal chimneys
William J. Brazeltona,1, Kristin A. Ludwiga,2, Mitchell L. Soginb, Ekaterina N. Andreishchevab, Deborah S. Kelleya, Chuan-Chou Shenc, R. Lawrence Edwardsd and John A. Barossa
aSchool of Oceanography and Center for Astrobiology and Early Evolution, University of Washington, Seattle, WA 98195;
bJosephine Bay Paul Center, Marine Biological Laboratory at Woods Hole, Woods Hole, MA 02543;
cDepartment of Geosciences, National Taiwan University, Taipei 106, Taiwan ; and
dDepartment of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455
The Lost City Hydrothermal Field, an ultramafic-hosted system located 15 km west of the Mid-Atlantic Ridge, has experienced at least 30,000 years of hydrothermal activity. Previous studies have shown that its carbonate chimneys form by mixing of ～90 °C, pH 9–11 hydrothermal fluids and cold seawater. Flow of methane and hydrogen-rich hydrothermal fluids in the porous interior chimney walls supports archaeal biofilm communities dominated by a single phylotype of Methanosarcinales. In this study, we have extensively sampled the carbonate-hosted archaeal and bacterial communities by obtaining sequences of >200,000 amplicons of the 16S rRNA V6 region and correlated the results with isotopic (230Th) ages of the chimneys over a 1,200-year period. Rare sequences in young chimneys were commonly more abundant in older chimneys, indicating that members of the rare biosphere can become dominant members of the ecosystem when environmental conditions change. These results suggest that a long history of selection over many cycles of chimney growth has resulted in numerous closely related species at Lost City, each of which is preadapted to a particular set of reoccurring environmental conditions. Because of the unique characteristics of the Lost City Hydrothermal Field, these data offer an unprecedented opportunity to study the dynamics of a microbial ecosystem’s rare biosphere over a thousand-year time scale.
