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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. It may also be used to diagnose a fungal infection. [1] The name comes from the Danish bacteriologist Hans Christian Gram, who developed the technique in 1884. [2]
Using an aseptic technique, bacteria are placed on a slide and heat fixed. The slide is then suspended over a water bath with some sort of porus paper over it, so that the slide is steamed . Malachite green is applied to the slide, which can penetrate the tough walls of the endospores, staining them green.
Major applications include blood smears, bone marrow aspirates, semen analysis and cytology of various body fluids including urine and cerebrospinal fluid. [7] [8] Microbiologic agents, such as bacteria and fungi, also appear more easily in Diff-Quik. [3] This is useful for the detection of for example Helicobacter pylori from gastric and ...
A simple staining method for bacteria that is usually successful, even when the positive staining methods fail, is to use a negative stain. This can be achieved by smearing the sample onto the slide and then applying nigrosin (a black synthetic dye) or India ink (an aqueous suspension of carbon particles).
The first stage separates the liquid water and fat mixture from the solids. The second stage further separates the fat from the water. The solids may be used in food products, pet foods, etc., depending on the original materials. The separated fat may be used in food products, or if in surplus, may be diverted to soap making operations.
It is also the main component of soap scum, a white solid that forms when soap is mixed with hard water. Unlike soaps containing sodium and potassium, calcium stearate is insoluble in water and does not lather well. [2] Commercially it is sold as a 50% dispersion in water or as a spray dried powder.
An inoculation loop (also called a smear loop, inoculation wand or microstreaker) is a simple tool used mainly by microbiologists to pick up and transfer a small sample of microorganisms called inoculum from a microbial culture, e.g. for streaking on a culture plate. [1] [2] This process is called inoculation.
Dorner used heat as a step in the process, but it was time-consuming, so in 1933, Schaeffer and Fulton modified his method. Schaeffer and Fulton made the heating process a lot faster by using a Bunsen burner. Although this method was not the most beneficial, it was a lot more convenient than Dorner's method.