ABSTRACT
Microbial communities from various environments usually consist of diverse groups of phytoplankton, protists, bacteria, virus, and other particles of various sizes and origins. By X-ray microanalysis with the transmission electron microscope (TEM), more direct measurements may add to and improve estimates based on the above-mentioned methods. Advantages of the method are: direct determination of dry weight or carbon in single cells without any need for biovolume measurements; good estimates of size distribution of cells and of frequency of dividing cells. For preparation of microorganisms from dense cultures or samples, it may be convenient just to add a drop of culture to a grid, wait for 1 to 2 min, remove excess water by blotting with a filter paper, and air dry the preparations. This preparation method is mainly suitable for sampling of bacterioneuston, e.g., from the air-water interface. Grids are placed with the carbon-coated side on the water surface for 30 s, removed, and air dried.
