Electron microscopy of nocardial cell division

Abstract

Nocardia polychromogenes is an aerobic, gram (+), non-motile, partially acid-fast actinomycete with primary mycelia that fragment into bacillary and coccoid elements.For scanning electron microscopy, N. polychromogenes culture strain Waksman 3409-A was grown on Potato Dextrose Agar at 25 C for 12-72 h. Five mm2 sections of the colonies, including portions of the interior and perimeter were fixed by exposure to osmium fumes for 16-24 h and air dried for 2 h. Specimens, mounted on stubs and sputter coated with gold, were viewed in a Cambridge Stereoscan Mark II scanning electron microscope. For transmission electron microscopy, the organism was grown on Potato Dextrose Agar at 25 C for 12-32 h. Whole colonies, 1-2 mm in diameter, were fixed by exposure to osmium fumes for 24 h. After suspension in noble agar, cells taken from the periphery of the fixed colonies were stained with 0. 5% uranyl acetate made in acetate-veranol buffer.