生物谷报道：德国奥尔登堡大学海洋化学和生物学研究所的研究人员D'Hondt等和美国一群科学家在太平洋海底以下几百米深处的沉积层发现了许多迄今未知的微生物，并在实验中成功培养了部分细菌。美国《Science》杂志刊登了这一最新研究成果。
从沉积层样本的细菌中，获得了170多种纯的培养物。通过分子生物学定量其18s，分析表明，其中包括至少14个物种，许多还是迄今未知的。另外，他们还发现了一些细菌，与在花园泥土中能找到的细菌有“亲缘”关系。
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.
研究人员发现，许多分离出来的细菌与孢子成份有关，孢子可以长时间存活。至于这些来自“深层生物圈”的细菌对人类会不会有危险，研究人员认为，这种可能性微乎其微。他们还认为，由于这些微生物在沉积层的存在时间远比人类在地球上出现的时间长，他们一定适应了在压力很大和长时间饥饿的状态下生存。在实验室中，只需要很少的养料，一些细菌就能生长。
沉积层样本来自2002年初开展的一个国际海洋钻探科考项目。美德科学家为主的一个国际小组，在太平洋公海、加拉帕戈斯群岛附近和秘鲁近海的海底提取了样本。凭借科考船的先进装备，科考人员利用特殊的钻探技术，探到了海底以下420米的沉积层，它的形成年代大约在3000多万年前。德国马普学会海洋微生物学研究所的科学家参加了这一科考活动。
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.
