Gram negative and positive bacteria

1.	Gram negative and positive bacteria
Answer» Gram negative Bacteria are the bacteria which do not stain by gram staining and gram positive are the bacteria which get stain The gram-positive bacteria retain the crystal violet colour and stains purple whereas the gram-negative bacteria lose crystal violet and stain red. Thus, the two types of bacteria are distinguished by gram staining.Gram-negative bacteria are more resistant against antibodies because their cell wall is impenetrable.Gram-positive and gram-negative bacteria are categorized on the basis of the ability to hold the gram stain. The gram-negative bacteria are stained by a counterstain such as safranin and they are destained because of the alcohol wash. Hence under a microscope, they are noticeably pink in colour. Gram-positive bacteria, on the other hand, retains the gram stain and show a visible violet colour upon the application of mordant(iodine) and ethanol(alcohol).Gram-positive bacteria have a cell wall composed of multiple layers of peptidoglycan that forms a rigid and thick structure. Its cell wall additionally has teichoic acids and phosphate. The teichoic acids present in the gram-positive bacteria are of two types – the lipoteichoic acid and the teichoic wall acid. The cell wall is known as murein.

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