Bacterial Growth Requirements and Metabolism PDF

Bacterial Growth Requirements and Metabolism  Requirements for Bacterial Growth Carbon source Nitrogen source Essential nutrients eg vitamins Temperature The right atmosphere Inorganic ions, iron The right pH Water  Carbon & Nitrogen...

Bacterial Growth Requirements and Metabolism  Requirements for Bacterial Growth Carbon source Nitrogen source Essential nutrients eg vitamins Temperature The right atmosphere Inorganic ions, iron The right pH Water  Carbon & Nitrogen Carbon Sources – Simple carbohydrates, sugars, proteins – Some organisms can fix CO2 Nitrogen Sources – Protein, peptides and amino acids, DNA – Nitrates, ammonium salts – Some organisms can fix N2  More Essentials Essential Nutrients – Bacteria vary in their requirements Some can synthesize all their needs Others need complex organic molecules, blood, vitamins to grow. These are called fastidious. Temperature – Bacteria (like humans) grow best at certain temperatures. – Mesophiles grow best between 20-40°C. Other types are best adapted to growing below 15, or above 40-45. – Human pathogens are usually mesophiles.  Oxygen and Iron Oxygen – Acts as a final electron accepter in aerobic organisms. – The superoxide radical (O2-) is toxic and must be rendered safe for cells to survive. Anaerobic organisms lack the means to detoxify O2-. Iron – Required for enzyme action (a cofactor). – The iron bacteria need is insoluble. – Bacteria produce siderophores, which bind to iron ions and make it possible to import it.  The Right Environment pH – Most organisms prefer neutral conditions. – Bacteria tend to die in acidic conditions (pH