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High bacterial diversity in permanently cold marine sediments
K Ravenschlag1, K Sahm, J Pernthaler
1Molecular Ecology Group, Max-Planck-Institute for Marine Microbiology, D-28359 Bremen, Germany.
Applied and Environmental Microbiology
|September 3, 1999
Summary
Marine sediments harbor diverse sulfur-cycling bacteria, with potential sulfate reducers dominating. This study identified specific bacterial groups, including Desulfotalea, in cold environments, revealing high microbial diversity.
Area of Science:
- Microbial Ecology
- Marine Microbiology
- Molecular Biology
Background:
- Permanently cold marine sediments are unique environments harboring specialized microbial communities.
- Understanding microbial diversity and function in these extreme habitats is crucial for biogeochemical cycling.
Purpose of the Study:
- To characterize the microbial community structure in permanently cold marine sediments using 16S ribosomal DNA (rDNA) analysis.
- To identify dominant bacterial groups, particularly those involved in the sulfur cycle.
Main Methods:
- Construction of a 16S ribosomal DNA (rDNA) clone library from marine sediment DNA.
- Screening of 353 clones using group-specific oligonucleotide probes and dot blot hybridization.
- Further characterization of probe target groups using amplified rDNA restriction analysis (ARDRA).
- Diversity assessment using rarefaction analysis.
Main Results:
- A significant proportion of clones (43.4%) were identified as potential sulfate reducers.
- The dominant group (19.0%) was affiliated with Desulfotalea sp. and other psychrophilic sulfate reducers.
- Other frequently encountered groups included Desulfuromonas palmitatis (13%) and Myxobacteria/Bdellovibrio spp.
- A notable fraction (18.1%) belonged to gamma-Proteobacteria, closely related to sulfur oxidizers.
- ARDRA revealed diversity within identified groups.
- Rarefaction analysis indicated that the screened clones represented only a fraction of the total microbial diversity.
Conclusions:
- Permanently cold marine sediments host a highly diverse microbial community, with a strong representation of sulfur-cycling bacteria.
- Psychrophilic sulfate reducers, particularly Desulfotalea, are key components of these ecosystems.
- The study highlights the need for extensive sampling to fully capture the microbial diversity in such environments.