APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Aug. 1990, Vol. 56, No. 8, p. 2572-2575

Tangential Flow Filtration and Preliminary Phylogenetic Analysis of Marine Picoplankton

Stephen J. Giovannoni, Edward F. Delong, Thomas M. Schmidt, and Norman R. Pace

(Received 16 February 1990, Accepted 16 May 1990)

A procedure was developed for harvesting gram quantities of microbial biomass from oligotrophic waters, when mixed populations are present in low abundance. Picoplankton from Atlantic Ocean (Hydrostation S, Sargasso Sea) and Pacific Ocean (Aloha Station) sites were collected in a three-stage process: (i) collection of seawater through an intake covered with 10-µm-pore Nytex; (ii) concentration by a tangential flow filtration device equipped with 10 ft² (0.929 m²) of 0.1-µm-pore fluorocarbon membrane; (iii) collection of cells from concentrate by centrifugation. The overall efficiency of picoplankton recovery was at least 37%. The cellular morphotypes recovered matched those of the original population. DNA was prepared from frozen cell pellets by enzymatic digestion, solvent extraction, and isopycnic centrifugation. As indicated by the binding of kingdom-specific hybridization probes to the purified DNA, the Sargasso Sea picoplankton in this collection were largely eubacteria.