Bacterial Growth and Nutrition

Bacterial Nutrition and Growth

• Bacteria require a source of energy and the raw materials to build new cell components to grow.
• All cells have the ability to direct chemical reactions and organize molecules into specific structures.
• Chemical substances from outside the cell are transported inside and transformed.

Catabolic and Anabolic Reactions

• Catabolism results in energy, nutrients, and waste products.
• Anabolism is the synthesis of cell components from nutrients.

Macroelements / Macronutrients

• Potassium is required for enzyme activity, including protein synthesis.
• Calcium is required for heat resistance of spores.
• Magnesium is an enzyme co-factor, complexes with ATP, and stabilizes ribosomes and cell membranes.
• Iron is found in cytochromes and is a co-factor for enzymes and electron-carrying proteins.

Classification Based on Metabolism

• Heterotrophs require a source of carbon, such as glucose.
• Autotrophs use carbon dioxide as their sole or principal carbon source.
• Autotrophs are often photosynthetic.
• Microorganisms use a wide range of carbon sources.

Anabolism and Catabolism

• Anabolism is the process of transforming substances into new cellular components.
• Catabolism is the process of breaking down chemical compounds to release energy.

Nutritional Requirements

• Most bacteria require a source of carbon, hydrogen, oxygen, nitrogen, energy, water, and various ions.
• 95% of microbial cells' dry weight is composed of macroelements/macronutrients.
• Macroelements/macronutrients are required in large amounts.

Micronutrients / Trace Elements

• Micronutrients/trace elements are required by most cells and include manganese, zinc, cobalt, molybdenum, nickel, and copper.
• Micronutrients/trace elements are part of enzymes and cofactors, aiding in the catalysis of reactions and maintenance of protein structure.

Sources of Energy for Anabolic Reactions

• There are two sources of energy available to microorganisms: light energy trapped during photosynthesis (phototrophs) and energy derived from oxidizing organic or inorganic molecules (chemotrophs).

Classification of Microorganisms

• Chemoorganoheterotrophs use organic chemical energy, organic electron donors, and organic carbon sources.

Medically Relevant Bacteria

• Pathogenic bacteria derive their energy from metabolizing sugars, fats, and proteins.
• Growth requirements vary among pathogenic bacteria.

N/P/S Metabolism

• Microorganisms need to incorporate large quantities of nitrogen, phosphorus, and sulfur to grow.
• Nitrogen is needed for the synthesis of amino acids, purines, pyrimidines, carbohydrates, lipids, enzyme co-factors, and other substances.

Growth Factors

• Growth factors are organic compounds required because they are essential cell components or precursors and cannot be synthesized by the microorganism.
• Examples of growth factors include amino acids, purines and pyrimidines, and vitamins.

Another Criteria for Differentiation

• Prototrophs use the same nutrients as most naturally occurring members of the species.
• Auxotrophs are mutants that cannot synthesize a molecule necessary for growth and reproduction.