Hans Christian Gram

Hans Christian Joachim Gram ( * September 13, 1853 in Copenhagen, † November 15, 1938 ) was a Danish bacteriologist.

Life

Gram studied botany, and later medicine at the University of Copenhagen he was until the conclusion of 1883. 1891 Lecturer and received in the same year professor of pharmacology, 1900 for Medicine in Copenhagen.

Gram was 1883-1885 at the Berlin Municipal Hospital in collaboration with Carl Friedländer a way causative agent of pneumonia Streptococcus pneumoniae (gram positive) and Klebsiella pneumoniae ( Gram negative) to stain different.

Reason for the intensive research on staining for bacteria at the end of the 19th century was the poor visibility in the bright-field microscopy. Only with the development of phase contrast in the 30s of the 20th century they were visible without staining.

Background

Hans Christian Gram developed the staining method as an employee at Carl Friedländer in Berlin. He was looking for a staining method can be represented by the bacteria in animal tissues, were thus colored contrasting with the tissue cells. The staining found, published in 1884, but had only some bacteria, the Gram-positive, success. Émile Roux applied the method for dyeing differentiation of gram-positive and gram-negative bacteria, in particular for the determination of gonococci (gram- negative in contrast to many other cocci ) (Publication 1886).

Färbmethode

This staining (Gram staining) based on a then-unknown difference in cell wall structure of bacteria. Gram- positive bacteria have a thick cell wall, mainly composed of a complex situation consisting of murein. The Gram-negative bacteria only have a very thin wall of a one-to wenigschichtigen murein layer, also they have a second lipid membrane similar to a cytoplasmic membrane outside the cell wall. On staining with gentian violet with iodine Iodkalium solution forms a water-insoluble " paint " inside the cell. This paint can be washed with ethanol from gram-negative bacteria. However, ethanol can not penetrate through the thick cell wall of Gram-positive bacteria, hence the color coat remains in these cells. To color the other gram-negative bacteria, a counterstain is used with safranin or fuchsin.