FOOD TECHNOLOGY

Detailed explanation-1: -Gram-negative bacteria are surrounded by a thin peptidoglycan cell wall, which itself is surrounded by an outer membrane containing lipopolysaccharide. Gram-positive bacteria lack an outer membrane but are surrounded by layers of peptidoglycan many times thicker than is found in the Gram-negatives.

Detailed explanation-2: -A thick layer of peptidoglycan and the lack of an outer membrane are the main characteristics of Gram-positive cell walls; instead of lipopolysaccharides, Gram-positive bacteria have lipoteichoic acid and teichoic acid localized in the cell wall.

Detailed explanation-3: -Depending on pH growth conditions, the peptidoglycan forms around 40 to 90% of the cell wall’s dry weight of Gram-positive bacteria but only around 10% of Gram-negative strains. Thus, presence of high levels of peptidoglycan is the primary determinant of the characterisation of bacteria as Gram-positive.