華盛頓大學(xué)的研究人員利用454測(cè)序平臺(tái)對(duì)16S RNA基因進(jìn)行測(cè)序,，揭示出北極多年海冰和表層海水的微生物群體結(jié)構(gòu)。這一研究成果近日發(fā)表在微生物生態(tài)學(xué)權(quán)威雜志《國(guó)際微生物生態(tài)學(xué)會(huì)會(huì)刊》（The ISME Journal）上,。
北極多年海冰（MYI）的急劇減少表明這種環(huán)境可能在100年后就會(huì)消失,，取而代之的將是生態(tài)上完全不同的第一年冰（first-year ice）。為了更好地了解這種微生物多樣性喪失的影響,，華盛頓大學(xué)海洋與天文生物學(xué)學(xué)院的Jeff S Bowman領(lǐng)導(dǎo)的研究小組利用454測(cè)序平臺(tái),，對(duì)北極附近的兩處多年海冰的微生物群落進(jìn)行了詳細(xì)的研究。
在瑞典破冰船奧登號(hào)在北冰洋上航行期間,，研究人員在北冰洋中部采集了兩個(gè)多年海冰和三個(gè)海水樣本,。在提取和純化之后,，他們利用通用引物對(duì)16S rRNA基因進(jìn)行了擴(kuò)增。之后在454 GS FLX平臺(tái)上對(duì)擴(kuò)增后的DNA進(jìn)行了測(cè)序,，平均讀長(zhǎng)約200 bp,。
研究人員將多年海冰與周?chē)谋砻婧ＫM(jìn)行了比較，發(fā)現(xiàn)兩者有著很大的差異,。在30個(gè)可鑒定的目中,，只有10個(gè)存在于兩種環(huán)境中。令人吃驚的是,，盡管多年海冰的微生物群落豐富度有所下降,，但多樣性與海水相當(dāng)。藍(lán)藻這種微生物也是第一次在北極海冰中觀察到,。此外,，一些過(guò)去未曾報(bào)道的低豐度進(jìn)化枝也存在于海冰中。
研究人員假設(shè),，這種高水平的多樣性可能是因?yàn)槎嗄旰１鶢I(yíng)養(yǎng)物環(huán)境的“繁榮-蕭條”,，初級(jí)生產(chǎn)、鹽水排水等提供了微生物生長(zhǎng)所需營(yíng)養(yǎng)物的強(qiáng)烈季節(jié)性變化,。此外,，多年海冰環(huán)境的持久也在本次研究中，研究人員使用了“中等深度”的測(cè)序,，每個(gè)樣品只產(chǎn)生了數(shù)千個(gè)讀取,。這種方法僅需要測(cè)序運(yùn)行的一小部分，卻能定量評(píng)估海冰中的微生物群落結(jié)構(gòu),。
海洋中存在著豐富的微生物,，但是研究手段的限制成為當(dāng)代環(huán)境微生物學(xué)研究和海洋資源開(kāi)發(fā)的障礙。
幾年前,，哈佛大學(xué)的研究人員也采用454測(cè)序法檢測(cè)了深海中微生物多樣性,。研究結(jié)果表明，北大西洋海底和熱泉中的微生物比以前報(bào)道環(huán)境中的數(shù)量要高1-2個(gè)數(shù)量級(jí),，且比后者要復(fù)雜的多,。這些原始的微生物為新的基因組數(shù)據(jù)更新提供了無(wú)窮的資源。(生物谷 Bioon.com)
生物谷推薦原文出處：
The ISME Journal doi:10.1038/ismej.2011.76
Microbial community structure of Arctic multiyear sea ice and surface seawater by 454 sequencing of the 16S RNA gene
Jeff S Bowman, Simon Rasmussen, Nikolaj Blom, Jody W Deming, S|[oslash]|ren Rysgaard, Thomas Sicheritz-Ponten
Dramatic decreases in the extent of Arctic multiyear ice (MYI) suggest this environment may disappear as early as 2100, replaced by ecologically different first-year ice. To better understand the implications of this loss on microbial biodiversity, we undertook a detailed census of the microbial community in MYI at two sites near the geographic North Pole using parallel tag sequencing of the 16S rRNA gene. Although the composition of the MYI microbial community has been characterized by previous studies, microbial community structure has not been. Although richness was lower in MYI than in underlying surface water, we found diversity to be comparable using the Simpson and Shannon's indices (for Simpson t=0.65, P=0.56; for Shannon t=0.25, P=0.84 for a Student's t-test of mean values). Cyanobacteria, comprising 6.8% of reads obtained from MYI, were observed for the first time in Arctic sea ice. In addition, several low-abundance clades not previously reported in sea ice were present, including the phylum TM7 and the classes Spartobacteria and Opitutae. Members of Coraliomargarita, a recently described genus of the class Opitutae, were present in sufficient numbers to suggest niche occupation within MYI.
