title: Comparison of two direct-count techniques for enumerating aquatic bacteria.
abstract: Planktonic bacteria from an estuary were concentrated on membrane filters and counted with both a scanning electron microscope and an epi-illuminated fluorescent microscope. Counts on 0.2 micron Nuclepore filters (polycarbonate) were significantly higher (P less than 0.001) than counts on 0.2-micron Sartorius filters (cellulose). In contrast, there was not a statistically significant difference between the two techniques when Nuclepore filters were used (0.5 less than P less than 0.9). The average cell volume from this study area was 0.047 micron3. The estimated number of bacteria ranged from 10(6) to 10(7) bacteria per ml, representing from 4 to 40 mg of C per m3.
mesh_terms: D001419:Bacteria / Q000302:isolation & purification*; D001431:Bacteriological Techniques; D005069:Evaluation Studies as Topic; D008851:Micropore Filters; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D012623:Seawater; D014871:Water Microbiology