How do pH levels affect bacterial growth?

Bacterial growth is significantly influenced by pH levels, particularly because enzymes, which facilitate metabolic processes in bacteria, are sensitive to the acidity or alkalinity of their environment. Each bacterial species has an optimal pH range in which it thrives. When pH levels deviate from this range, the structure and function of enzymes can be disrupted, leading to denaturation. This denaturation can hinder the bacteria’s ability to catalyze necessary biochemical reactions, ultimately inhibiting growth or even leading to cell death.

For example, most bacteria grow well in neutral to slightly alkaline conditions (around pH 6.5 to 7.5). In contrast, extreme acidity (low pH) or alkalinity (high pH) can be detrimental, causing the enzymes to lose their shape and thus their activity. Certain bacteria, like acidophiles or alkaliphiles, are adapted to grow in extreme pH environments, but even they have limits beyond which growth is ceased. Therefore, option B accurately captures the essential role of pH in influencing bacterial growth through its effects on enzyme functionality.