Genetic comparisons reveal the same unknown bacterial lineages in Atlantic and Pacific bacterioplankton communities

Abstract

The phylogenetic diversity of oligotrophic bacterioplankton communities was compared with 16S ribosomal RNA genes cloned from natural populations. The data reported here extend a previous analysis of a bacterioplankton 16S rRNA clone library with 15 additional nucleic acid clone sequences, to provide information on 60 16S rDNA clones from hydrostation S in the Sargasso Sea. The data were compared to partial sequences of 37 Bacterial 16S rDNA clones reported from a surface picoplankton population collected at the Aloha station in the North Pacific gyre, and partial sequences of 29 Bacterial 1 6S rRNA clones obtained from sites near Bermuda and the western California Current. The results support reports of diverse groups of previously unknown a‐proteobacteria, γ‐proteobacteria, and cyanobacteria in oceanic surface samples. Three novel lineages (SAR 121, 125, 145) of proteobacteria were found. Several genes cloned from the Sargasso Sea were nearly identical to genes cloned from the Pacific samples, suggesting that these previously unrecognized bacteria groups (SAR11, SAR122, SAR86) are distributed widely in the surface waters of subtropical oceans. Two gene clones closely matched nucleotide sequences from the cultivated bacterial species Photobacterium phosphoreum and A lteromonas haloplanktis.