Isolation and characterization of filterable marine bacteria.

Anderson, J. I. W. (Northeast Shellfish Sanitation Research Center, Narragansett, R.I.), and W. P. Heffernan. Isolation and characterization of filterable marine bacteria. J. Bacteriol 90:1713-1718. 1965.-By a process of double filtration of seawater, first through a membrane filter with a pore diameter of 0.45 mu and then through a membrane filter with a pore diameter of 0.22 mu, it was possible to isolate on the surface of the latter membrane a group of marine organisms not usually encountered by conventional techniques of pour plates or one-stage filtration. Many of the isolates could not be identified, but the largest single group belonged to the genus Spirillum; other isolates were placed in the genera Leucothrix, Flavobacterium, Cytophaga, and Vibrio. A group of four organisms which was not identified was characterized by the formation of large, club-shaped cells, 20 to 30 mu long. Of the 25 strains studied in detail, 22 required seawater for growth and 8 retained their filterable property after cultivation. No filterable bacteria were isolated from terrestrial samples.