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.
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 '(i), (ii) and (iii)'.
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 $$(4)$$.
Outer layer of lipopolysaccharide is characteristic of
Wall of Gram +ve bacteria possess
Gram negative bacteria possess