生物谷報(bào)道：德國(guó)奧爾登堡大學(xué)海洋化學(xué)和生物學(xué)研究所的研究人員D'Hondt等和美國(guó)一群科學(xué)家在太平洋海底以下幾百米深處的沉積層發(fā)現(xiàn)了許多迄今未知的微生物，并在實(shí)驗(yàn)中成功培養(yǎng)了部分細(xì)菌,。美國(guó)《Science》雜志刊登了這一最新研究成果,。
從沉積層樣本的細(xì)菌中，獲得了170多種純的培養(yǎng)物,。通過(guò)分子生物學(xué)定量其18s,，分析表明，其中包括至少14個(gè)物種,，許多還是迄今未知的,。另外，他們還發(fā)現(xiàn)了一些細(xì)菌,，與在花園泥土中能找到的細(xì)菌有“親緣”關(guān)系,。
Fig. 1. Map of Leg 201 sites and concentration profiles of several dissolved chemical species at five of the sites (17). At sites 1225, 1226, and 1231, the deepest sample was taken just above the basaltic basement.
研究人員發(fā)現(xiàn)，許多分離出來(lái)的細(xì)菌與孢子成份有關(guān),，孢子可以長(zhǎng)時(shí)間存活,。至于這些來(lái)自“深層生物圈”的細(xì)菌對(duì)人類(lèi)會(huì)不會(huì)有危險(xiǎn),，研究人員認(rèn)為，這種可能性微乎其微,。他們還認(rèn)為,，由于這些微生物在沉積層的存在時(shí)間遠(yuǎn)比人類(lèi)在地球上出現(xiàn)的時(shí)間長(zhǎng)，他們一定適應(yīng)了在壓力很大和長(zhǎng)時(shí)間饑餓的狀態(tài)下生存,。在實(shí)驗(yàn)室中,，只需要很少的養(yǎng)料，一些細(xì)菌就能生長(zhǎng),。
沉積層樣本來(lái)自2002年初開(kāi)展的一個(gè)國(guó)際海洋鉆探科考項(xiàng)目,。美德科學(xué)家為主的一個(gè)國(guó)際小組，在太平洋公海,、加拉帕戈斯群島附近和秘魯近海的海底提取了樣本,。憑借科考船的先進(jìn)裝備，科考人員利用特殊的鉆探技術(shù),，探到了海底以下420米的沉積層,，它的形成年代大約在3000多萬(wàn)年前。德國(guó)馬普學(xué)會(huì)海洋微生物學(xué)研究所的科學(xué)家參加了這一科考活動(dòng),。
Fig. 2. Concentration profiles of cells and some dissolved chemicals at site 1229 (17). White bands mark sulfate-methane transition zones. Arrows mark midcolumn peaks in dissolved Mn concentrations.
Fig. 3. Dissolved concentration profiles of NO3– (red diamonds), Mn (light blue squares), and Fe (dark blue circles) at open-ocean sites 1225 (A), 1226 (B), and 1231 (C). Arrows mark midcolumn peaks in dissolved concentrations of Mn and Fe at site 1226. At each site, the deepest sample was taken just above the basaltic basement.
Cultured bacterial isolates from Leg 201 sediments. Species listed are type species from GenBank database.
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Closest relative (16S rRNA sequence similarity) Numbers of isolates (lowest and highest depth of discovery)
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Open Pacific sites
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Peru margin sites
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1231 1225 1226 1227 1228 1229 1230
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-Proteobacteria
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Rhizobium radiobacter (98%) 7 (1 to 198 mbsf) 2 (1 to 381 mbsf) 14 (12 to 102 mbsf) 5 (12 to 70 mbsf) 13 (1 to 124 mbsf)
Rhodobacter capsulatus (95%)* 1 (268 mbsf)
Rhodovulum sulfidophilum (96%) 1 (43 mbsf)
Firmicutes
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Bacillus firmus (97%) 14 (2 to 43 mbsf) 12 (1 to 420 mbsf) 8 (1 to 102 mbsf) 34 (1 to 187 mbsf)
Bacillus simplex (96%)* 1 (1 mbsf) 1 (70 mbsf)
Alkaliphilus transvaalensis (96%)* 4 (1 mbsf)
Paenibacillus glucanolyticus (98%) 1 (198 mbsf)
-Proteobacteria
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Vibrio mediterranei (99%) 1 (101 mbsf) 6 (1 to 114 mbsf) 11 (1 to 187 mbsf)
Vibrio diazotrophicus (99%)* 1 (114 mbsf) 4 (1 to 82 mbsf)
Photobacterium fischeri (94%) 1 (1 mbsf)
Psychrobacter okhotskensis (98%) 3 (1 to 124 mbsf)
Marinobacter aquaeolei (95%) 1 (268 mbsf)
Marinobacter excellens (98%)* 2 (268 mbsf)
Actinobacteria
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Micrococcus luteus (98%) 2 (1 to 307 mbsf) 1 (381 mbsf)
Kocuria palustris (99%) 4 (21 to 40 mbsf)
Oerskovia paurometabola (92%) 3 (2 to 101 mbsf) 5 (40 to 55 mbsf)
-Proteobacteria
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Desulfomicrobium norvegicum (99%)* 2 (103 mbsf)
Bacteroidetes
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Porphyromonas endodontalis (86%)
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1 (198 mbsf)
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* Species names identify the type species in the GenBank database that are the closest relatives of the cultured isolates. The genetic distance between each cultured taxon and its closest relative is illustrated by the percent similarity of their 16S rRNA sequences.
