Gram reaction , negative or positive , is one of the most effective ways of classifying bacteria, with gram negative having an extra layer of cell wall that prevents dsipaly any reaction to dyes. Forms redish or pinkish color with safranin, besides containing lesser amount of RNA , thin layer of peptidogyl and highly charged nature of lipopolysaccharides responsible for antigenic properties , when these are compared with Gram -positive reaction...
Gram reaction , negative or positive , is one of the most effective ways of classifying bacteria, with gram negative having an extra layer of cell wall that prevents dsipaly any reaction to dyes. Forms redish or pinkish color with safranin, besides containing lesser amount of RNA , thin layer of peptidogyl and highly charged nature of lipopolysaccharides responsible for antigenic properties , when these are compared with Gram -positive reaction...
thank you, I heard some of bacteria some time are gram positive and some time negative? please explain about it...
The distinction of bacteria on the Gram-negative or Gram-positive is done by Gram staining (Gram's method). This technique can give incorrect results when performed in bad conditions. In addition, some types of bacteria may react differently to staining. For example, Mycobacterium is a "Gram-indeterminate" bacteria and do not respond predictably to staining. Also smaller bacteria (e.g. Treponema, Chlomydia, Rickettsia) are difficult to stain with the classic Gram method. On the other hand, some species of fungi (e.g. Candida and Cryptococcus) may give a positive response. Also the age of the culture may influence the results of the stain.
During Grams staining, gram negative bacteria lose the crystal violet stain and take the color of the red counter stain. Gram negative is a characteristic of a bacteria that have cell wall composed of thin layer of a peptidoglycon.
Anoop, thank you for your kind words.
Gram's method is a classic microbiological method, but I know that it can sometimes be problematic in practice. I hope that it was a helpful answer.
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