Outer layer of lipopolysaccharide is characteristic of
The Gram-negative cell wall is characterised by the presence of outer membrane, a thinner peptidoglycan layer and extensive periplasmic space surrounding the peptidoglycan. The uppermost layer of the outer membrane has lipopolysaccharide while the innermost layer is a typical lipid layer. Option B is correct. Gram-positive cells are characterised by the presence of a single thick layer of cell wall which is made up of peptidoglycan, teichoic acid and lipoteichoic acid. They lack outer membrane. This makes options A and C incorrect. Thus, the correct answer is option B.
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 $$(4)$$.
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.
Wall of Gram +ve bacteria possess
Gram negative bacteria possess