A numerical taxonomic study of cold ocean marine bacteria from the northwest Atlantic near Newfoundland

Abstract

One hundred and forty bacterial strains were isolated from two sources, giant scallop (Placopecten magellanicus) and seaweed (Alaria esculenta). The isolations from the seaweed were made on three successive occasions during the natural degradation of the fronds. Nine type strains from the genera Vibrio, Pseudomonas, Alteromonas, and Photobacterium were also included. Approximately 150 characterization tests were scored for each strain. All of the cold ocean strains were gram-negative, motile rods and required Na⁺ for growth. Approximately 60% were fermentative. The results of 112 tests were explored using cluster analysis and a variety of methods yielded six robust clusters. These clusters conformed largely to source of strains. The strains from A. esculenta clustered separately from those isolated from P. magellanicus. To some extent the clusters could be further distinguished as containing either oxidative or fermentative strains and, in the case of the seaweed isolates, by time of isolation, i.e., early or later in the degradation process. Tests which discriminated each cluster were identified. The predominant bacteria isolated were from the genera Vibrio, Pseudomonas and Alteromonas. Although some of the strains could be identified at the species level other could not. The latter strains may represent new species of marine bacteria.