pH Basics and Microorganism Preferences PDF

Yogurt, pickles, sauerkraut, and lime dishes taste tangy due to their high acidity, measured by pH. Acidity affects macromolecules like DNA, lipids, and proteins. pH Basics: ○ pH < 7.0: Acidic ○ pH > 7.0: Basic ○ pH affects macromolecule structure:...

Yogurt, pickles, sauerkraut, and lime dishes taste tangy due to their high acidity, measured by pH. Acidity affects macromolecules like DNA, lipids, and proteins. pH Basics: ○ pH < 7.0: Acidic ○ pH > 7.0: Basic ○ pH affects macromolecule structure: High pH can break DNA bonds. Extreme basicity can break down lipids. Proteins are very sensitive to pH changes, affecting their shape and function. Growth pH: ○ Optimum Growth pH: Best pH for organism growth. ○ Minimum Growth pH: Lowest tolerable pH. ○ Maximum Growth pH: Highest tolerable pH. ○ Example: Salmonella spp. optimum pH is 7.0–7.5, minimum is around 4.2. Microorganism Preferences: ○ Neutrophiles: Most bacteria (e.g., E. coli, Salmonella) thrive near pH 7.0; they struggle in acidic environments. ○ Fungi: Prefer slightly acidic pH (5.0–6.0). ○ Acidophiles: Prefer pH < 5.55 (e.g., Sulfolobus spp. thrive at pH 2.5–3.5; Ferroplasma at pH 0–2.9). ○ Lactobacillus: Important for vaginal acidity (pH ~4), helps inhibit other microbes. ○ Alkaliphiles: Prefer pH 8.0–10.5 (e.g., Vibrio cholerae thrives at pH 8.0, survives pH 11.0). Adaptations: ○ Acidophiles have proteins that are stable in low pH and pump out H+ ions to survive. ○ Alkaliphiles adapt their lipid and protein structures to thrive in high pH.