High-throughput isolation of pelagic marine bacteria from the coastal subtropical Pacific Ocean

Abstract

In an effort to isolate and grow strains of microorganisms that are representative of the major marine microbial groups typical of surface seawater of the largest ecosystem on our planet, the North Pacific Subtropical Gyre, a high-throughput extinction culture experiment was undertaken within and immediately outside of Kane'ohe Bay, a coastal embayment on the eastern side of the Hawai'ian island of Oahu. The objectives of this experiment were two-fold: first, to create, maintain, and cryopreserve a collection of isolates for laboratory-based investigation and dissemination, and second, to use non-cultivation based, molecular methods to assay the phylogenetic diversity of bacterioplankton within the water mass serving as the source inocula in order to compare the phylogenetic identity of the in situ microbial community with that of the resulting isolates. Somewhat surprisingly, we were able to obtain cultures of the majority of the major groups of marine bacteria detected by cultivation-independent techniques in the water masses we sampled, including novel members of the SAR11 and SARI16 clades of bacteria that had evaded all previous cultivation attempts, thus generating a rich library of microbial strains for future research aimed at elucidating their roles in carbon, energy, and nutrient cycling in the North Pacific Subtropical Gyre.