Arrange the following steps in a correct sequence as per Gram's staining technique: Treatment with $$0.5$$% iodine solution $$(1)$$, washing with water $$(2)$$, treatment with absolute alcohol/ acetone $$(3)$$, staining with weak alkaline solution of crystal violet $$(4)$$.
Bacteria can be classified into two groups based upon reaction of bacteria to Gram's stain (Christian Gram, $$1884$$). Bacteria are first stained with weakly alkaline solution of crystal violet and then treated with $$0.5$$% iodine solution. This is followed by washing with water and then with alcohol or acetone. Bacteria which retain blue or purple colour are known as Gram $$(+)$$ bacteria (e.g., Bacillus subtilis). Bacteria which do not retain stain and become colourless are called Gram $$(-)$$ bacteria (e.g., Escherichia coli). Washing of the stain in Gram $$(-ve)$$ bacteria is due to high lipid content of their cell wall which gets dissolved in organic solvents like acetone.
So, the correct answer is '$$4\rightarrow 1 \rightarrow 2\rightarrow 3$$'.
Select the correct option: Which of the given statements are correct? (i) Bacillus subtilis is a Gram $$(+)$$ bacteria. (ii) Escherichia coli is a Gram $$(-)$$ bacteria. (iii) Washing of the Gram's stain in Gram $$(-)$$ bacteria is due to high lipid content of the cell wall, which gets dissolved in organic solvent like acetone.
Outer layer of lipopolysaccharide is characteristic of
Wall of Gram +ve bacteria possess
Gram negative bacteria possess