بكتيريا سلبية الغرام وفعالية الماء

Gram-Negative Bacteria and Water Activity

• Gram-negative bacteria have an outer membrane made of lipopolysaccharides. This membrane acts as a barrier, preventing molecules like water from entering easily.
• Consequently, Gram-negative bacteria need a higher water activity level to grow and survive compared to Gram-positive bacteria. They need more water to penetrate this barrier and access nutrients.

Cell Wall Structure and Osmotic Stress

• Gram-negative bacteria have a thinner peptidoglycan layer in their cell walls compared to Gram-positive bacteria.
• This thinner layer makes them more vulnerable to osmotic stress, which can occur in environments with low water activity.
• To avoid osmotic stress and maintain cell integrity, Gram-negative bacteria often require higher water activity levels.