ABSTRACT
Bacteria are extremely minute, rigid, essentially unicellular organisms (actinomycetes are filamentous), devoid of chlorophyll, most commonly reproduce by transverse binary fission and the resulting cells are identical in size and morphology. Flagella is a hair like helical structures that protrude through cell wall and are used for locomotion. The Gram staining is one of the most crucial staining techniques in microbiology. It gets its name from the Danish bacteriologist Hans Christian Gram who first introduced it in 1882, mainly to identify organisms causing pneumonia. The basic principle of gram staining involves the ability of the bacterial cell wall to retain the crystal violet dye during solvent treatment. Gram-positive microorganisms have higher peptidoglycan content, whereas gram-negative organisms have higher lipid content. Bacterial cell wall is further divided into two categories, the gram-positive and gram-negative bacteria. The main difference between these two layers is the thickness level of the peptidoglycan layer.
