Characterization of psychrotrophic bacteria in the surface and deep-sea waters from the northwestern Pacific Ocean based on 16S ribosomal DNA analysis

Seventy-eight 4 degreesC-culturable bacteria were isolated using ZoBell 221 6E medium from surface (0-200 m) and deep-sea (1000-9671 m) waters in the n orthwestern Pacific Ocean. Growth studies indicated that all 4 degreesC-cul turable bacteria were psychrotrophs. Six phylotypes were observed in the su rface water samples and 8 phylotypes in the deep-sea waters. Phylogenetic c haracterization based on 16S ribosomal DNA sequence analysis of the represe ntative phylotypes revealed that some bacterial genera, Pseudoalteromas, Ph otobacterium, and Vibrio, were common to surface and deep-sea waters, and o thers, Pseudomonas and Halomonas, specifically occurred in surface water. O verall, the members of Vibrionaceae appear to be dominant in both habitats. habitats.