title: Comparative ultrastructure of a mucoid strain of Pseudomonas aeruginosa isolated from cystic fibrosis patient and its spontaneous non-mucoid mutant.
abstract: The ultrastructure of a mucoid strain of Pseudomonas aeruginosa of cystic fibrosis origin and its spontaneous non-mucoid variant was compared by transmission electron microscopy. Negatively-stained preparations of the mucoid strain obtained from plate cultures demonstrated dense, fibrous material projecting from the cell. No such material was observed in thin-sections or in negatively-strained preparations from liquid cultures. Thin-sections of ethanol-precipitated extracellular material from liquid cultures of the mucoid-strain revealed a cottony mesh of thin electron dense fibres. The non-mucoid strain did not produce such material. When prefixed with glutaraldehyde/malachite green mixture, cells of both strains demonstrated electron dense intracellular and extracellular malachite green-stainable structures. The internal complexes were frequently associated with the nucleoid or cell membrane and were replaced by electron transparent areas in cells prefixed with glutaraldehyde alone. Aeruginocins of the R-type were observed in mitomycin C induced cultures of both strains. Bacteriophages with 'claw-shaped' tail-tips were observed in the mucoid strain. Crystalline material was produced by the mucoid strain but only when plated on certain media.
mesh_terms: D001430:Bacteriocins / Q000032:analysis; D001435:Bacteriophages / Q000302:isolation & purification; D003460:Crystallization; D003550:Cystic Fibrosis / Q000382:microbiology*; D006801:Humans; D009154:Mutation; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D011550:Pseudomonas aeruginosa / Q000032:analysis / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D001430:Bacteriocins; D011135:Polysaccharides, Bacterial; C012706:aeruginocin