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Gram Stain
In microbiology and bacteriology, Gram stain (Gram staining or Gram's method), is a method of staining used to classify bacterial species into two large groups: gram-positive bacteria and gram-negative bacteria. The name comes from the Danish bacteriologist Hans Christian Gram, who developed the technique in 1884. Gram staining differentiates bacteria by the chemical and physical properties of their cell walls. Gram-positive cells have a thick layer of peptidoglycan in the cell wall that retains the primary stain, crystal violet. Gram-negative cells have a thinner peptidoglycan layer that allows the crystal violet to wash out on addition of ethanol. They are stained pink or red by the counterstain, commonly safranin or fuchsine. Lugol's iodine solution is always added after addition of crystal violet to strengthen the bonds of the stain with the cell membrane. Gram staining is almost always the first step in the preliminary identification of a bacterial organism. While Gram ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karl Bernhard Lehmann
Karl Bernhard Lehmann (27 September 1858 – 30 January 1940) was a German hygienist and bacteriologist born in Zurich. He was a brother to publisher Julius Friedrich Lehmann (1864–1935). Lehmann studied medicine at the University of Munich, where one of his instructors was Max von Pettenkofer (1818–1901). In 1886, he received his habilitation, and from 1894 to 1932 was a full professor of hygiene at the University of Würzburg (emeritus 1932).Lehmann, Karl Bernhard Neue Deutsche Biographie (NDB). Band 14, Duncker & Humblot, Berlin 1985, , S. 71 f. He is remembered for pioneer research he performed with Ferdinand Flury (1877–1947), of which the exposure limits of various ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rudolf Otto Neumann
Rudolf Otto Neumann (29 June 1868, Seifhennersdorf - 5 April 1952, Hamburg) was a German hygienist. He studied pharmacy and medicine at the Universities of Greifswald, Leipzig, Erlangen and Würzburg, receiving his habilitation in 1902 at the University of Kiel. In 1904 he relocated to Hamburg, where he was appointed departmental head of the state hygienic institute. During the same year he was part of an expedition to Brazil in order to research yellow fever. From 1906 to 1910 he worked at the institute of hygiene at the University of Heidelberg, followed by a professorship in hygiene and bacteriology at the University of Giessen. In 1914 he was appointed director of the hygiene institute at the University of Bonn, and in 1922 succeeded William Philipps Dunbar (1853–1922) as director of the hygiene institute at the University of Hamburg. Neumann participated in many scientific trips during his career, including extended journeys to the Far East, the United States and Central ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corynebacterium Xerosis Colonial Morphology On Blood Agar
''Corynebacterium'' () is a genus of Gram-positive bacteria and most are aerobic. They are bacilli (rod-shaped), and in some phases of life they are, more specifically, club-shaped, which inspired the genus name (''coryneform'' means "club-shaped"). They are widely distributed in nature in the microbiota of animals (including the human microbiota) and are mostly innocuous, most commonly existing in commensal relationships with their hosts. Some, such as '' C. glutamicum'', are commercially useful. Others can cause human disease, including, most notably, diphtheria, which is caused by '' C. diphtheriae''. As with various species of amicrobiota (including their relatives in the genera ''Arcanobacterium'' and ''Trueperella''), they usually are not pathogenic, but can occasionally opportunistically capitalize on atypical access to tissues (via wounds) or weakened host defenses. Taxonomy The genus ''Corynebacterium'' was created by Lehmann and Neumann in 1896 as a taxonomic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
