DIRECT ELECTRON-MICROSCOPY STUDY ON THE MORPHOLOGICAL DIVERSITY OF BACTERIOPHAGE POPULATIONS IN LAKE PLUSSEE

Direct electron microscopy of bacteriophages adsorbed to a carbon film without prior enrichment by specific host strains or concentration by physical or chemical methods was used to study the morphological dive rsity of natural bacteriophage assemblages in a North German lake. All samples contained a mixture of morphologically different tailed virus es, which were regarded as bacteriophages. Most of them had isometric heads and long noncontractile-tails, belonging to morphotype B1 (Sipho viridae). In addition, members of morphotypes A1 (Myoviridae), B2 (Sip hoviridae with elongated heads), and C1 (Podoviridae) were present in lower numbers. Only one cubic virus was detected, while no filamentous or pleomorphic phages were found. Up to 11 different phages per sampl e, and a total of 39 phages when all samples were considered together, could be distinguished by morphological criteria. The total number of phages was estimated to be on the order of 10(8)/ml.