Journal ArticleDOI
Genetic diversity in Sargasso Sea bacterioplankton.
TLDR
The phylogenetically analysed clone libraries of eubacterial 16S ribosomal RNA genes amplified from natural populations of Sargasso Sea picoplankton indicate the presence of a novel microbial group, the SAR 11 cluster, which appears to be a significant component of this oligotrophic bacterioplankton community.Abstract:
BACTERIOPLANKTON are recognized as important agents of biogeochemical change in marine ecosystems, yet relatively little is known about the species that make up these communities. Uncertainties about the genetic structure and diversity of natural bacterioplankton populations stem from the traditional difficulties associated with microbial cultivation techniques. Discrepancies between direct counts and plate counts are typically several orders of magnitude, raising doubts as to whether cultivated marine bacteria are actually representative of dominant planktonic species1–3. We have phylogenetically analysed clone libraries of eubacterial 16S ribosomal RNA genes amplified from natural populations of Sargasso Sea picoplankton by the polymerase chain reaction4. The analysis indicates the presence of a novel microbial group, the SAR 11 cluster, which appears to be a significant component of this oligotrophic bacterioplankton community. A second cluster of lineages related to the oxygenic phototrophs—cyanobacteria, prochlorophytes and chloroplasts—was also observed. However, none of the genes matched the small subunit rRNA sequences of cultivated marine cyanobacteria from similar habitats. The diversity of 16S rRNA genes observed within the clusters suggests that these bacterioplankton may be consortia of independent lineages sharing surprisingly distant common ancestors.read more
Citations
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Direct amplification of nodD from community DNA reveals the genetic diversity of Rhizobium leguminosarum in soil
TL;DR: It is concluded that clover selects specific genotypes from the available soil population, and that R. leguminosarum biovar trifolii was approximately five times more abundant thanBiovar viciae in this pasture soil, whereas S. meliloti was rare.
Journal ArticleDOI
Characterization of the gill symbiont of Thyasira flexuosa (Thyasiridae: Bivalvia) by use of polymerase chain reaction and 16S rRNA sequence analysis.
D L Distel,A P Wood +1 more
TL;DR: Strain TG-2 most closely resembles a free-living, chemolithoautotrophic bacterium known to be associated with the surfaces of thiotrophic bivalve shells, suggesting that this strain is a contaminant and not the authentic intracellular symbiont of T. flexuosa.
Journal ArticleDOI
Growth of uncultured heterotrophic flagellates in unamended seawater incubations
TL;DR: Unamended dark incubations of 3 µm-filtered seawater incubations can select for heterotrophic flagellates abundant in situ but not yet isolated in pure culture, and provide promising preliminary stages for their isolation.
Journal ArticleDOI
Comparison of 16S rRNA and 16S rDNA T-RFLP Approaches to Study Bacterial Communities in Soil Microcosms Treated with Chromate as Perturbing Agent
Alessio Mengoni,Enrico Tatti,Francesca Decorosi,Carlo Viti,Marco Bazzicalupo,Luciana Giovannetti +5 more
TL;DR: Community profiles derived from RNA and DNA were partly overlapping; there was a strong correlation between the dynamics shown by RNA- and DNA-based T-RFLP profiles; chromate addition exerted a clear effect on both agricultural and serpentine soil bacterial communities.
Journal ArticleDOI
Measurement of rRNA Variations in Natural Communities of Microorganisms on the Southeastern U.S. Continental Shelf.
TL;DR: Variations in the rRNA content from Synechococcus spp.
References
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DNA sequencing with chain-terminating inhibitors
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TL;DR: A thermostable DNA polymerase was used in an in vitro DNA amplification procedure, the polymerase chain reaction, which significantly improves the specificity, yield, sensitivity, and length of products that can be amplified.
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Site-directed mutagenesis by overlap extension using the polymerase chain reaction.
TL;DR: In this paper, complementary oligodeoxyribonucleotide (oligo) primers and the polymerase chain reaction are used to generate two DNA fragments having overlapping ends, and these fragments are combined in a subsequent 'fusion' reaction in which the overlapping ends anneal, allowing the 3' overlap of each strand to serve as a primer for the three' extension of the complementary strand.
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