Affiliation:
1. Unidad de Microbiologı́a, Centro de Biologı́a Molecular y Celular, Universidad Miguel Hernández, Campus de San Juan, 03550 San Juan, Alicante,1 and
2. División de Microbiologı́a, Departamento de Biotecnologı́a, Universidad de Alicante, 03080 Alicante,2 Spain
Abstract
ABSTRACT
In a previous study (S. G. Acinas, F. Rodrı́guez-Valera, and C. Pedrós-Alió, FEMS Microbiol. Ecol. 24:27–40, 1997), community fingerprinting by 16S rDNA restriction analysis applied to Mediterranean offshore waters showed that the free-living pelagic bacterial community was very different from the bacterial cells aggregated or attached to particles of more than about 8 μm. Here we have studied both assemblages at three depths (5, 50, and 400 m) by cloning and sequencing the 16S rDNA obtained from the same samples, and we have also studied the samples by scanning electron microscopy to detect morphology patterns. As expected, the sequences retrieved from the assemblages were very different. The subsample of attached bacteria contained very little diversity, with close relatives of a well-known species of marine bacteria,
Alteromonas macleodii
, representing the vast majority of the clones at every depth. On the other hand, the free-living assemblage was highly diverse and varied with depth. At 400 m, close relatives of cultivated γ
Proteobacteria
predominated, but as shown by other authors, near the surface most clones were related to phylotypes described only by sequence, in which the α
Proteobacteria
of the SAR11 cluster predominated. The new technique of rDNA internal spacer analysis has been utilized, confirming these results. Clones representative of the
A. macleodii
cluster have been completely sequenced, producing a picture that fits well with the idea that they could represent a genus with at least two species and with a characteristic depth distribution.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
249 articles.
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