Previous Article | Next Article ![]()
Appl. Environ. Microbiol., 03 1997, 983-989, Vol 63, No. 3
MT Suzuki, MS Rappe, ZW Haimberger, H Winfield, N Adair, J Strobel and SJ Giovannoni
Numerous investigations applying the cloning and sequencing of rRNA genes
(rDNAs) to the study of marine bacterioplankton diversity have shown that
the sequences of genes cloned directly from environmental DNA do not
correspond to the genes of cultured marine taxa. These results have been
interpreted as support for the hypothesis that the most abundant
heterotrophic marine bacterioplankton species are not readily culturable by
commonly used methods. However, an alternative explanation is that marine
bacterioplankton can be easily cultured but are not well represented in
sequence databases. To further examine this question, we compared the
small-subunit (SSU) rDNAs of 127 cellular clones isolated from a water
sample collected off the Oregon coast to 58 bacterial SSU rDNAs cloned from
environmental DNAs from the same water sample. The results revealed little
overlap between partial SSU rDNA sequences from the cellular clones and the
environmental clone library. An exception was the SSU rDNA sequence
recovered from a cellular clone belonging to the Pseudomonas subgroup of
the gamma subclass of the class Proteobacteria, which was related to a
single gene cloned directly from the same water sample (OCS181)
(similarity, 94.6%). In addition, partial SSU rDNA sequences from three of
the cultured strains matched a novel rDNA clone related to the gamma
subclass of the Proteobacteria found previously in an environmental clone
library from marine aggregates (AGG53) (similarity, 94.3 to 99.6%). Our
results support the hypothesis that many of the most abundant
bacterioplankton species are not readily culturable by standard methods but
also show that heterotrophic bacterioplankton that are culturable on media
with high organic contents include many strains for which SSU rDNA
sequences are not available in sequence databases.
Copyright © 1997, American Society for Microbiology
Bacterial diversity among small-subunit rRNA gene clones and cellular isolates from the same seawater sample
College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis 97331, USA.
This article has been cited by other articles:
| J. Bacteriol. | Microbiol. Mol. Biol. Rev. | Eukaryot. Cell | All ASM Journals |
|---|