Microbial Nutrition
All of life involves chemistry. Chemicals are used for all processes and all activities. Reproduction is a chemical process.
The chemical processes of life are known as metabolism. Metabolism:
• Supplies Energy
• Chemicals for Cell Structures
• Energy and Materials for Reproduction
• Motion
Metabolism that requires energy is called anabolism. Metabolism that releases energy is called catabolism.
Chemicals that are required for life are called nutrients.
Macronutrients
The primary nutrients are hydrogen, oxygen, carbon, nitrogen, phosphorous, and sulfur. However, there are more than 50 elements that are metabolized by microorganisms.
Carbon is the most abundant element in microorganisms. Cells of microorganism are about 50% carbon on a dry weight basis (with all water removed). Heterotrophs are microorganisms that use organic carbon for both anabolic and catabolic reaction. There are many sources of organic carbon (sugars, organic acid, fatty acids plus many more). Organic carbon will have hydrogen.
Autotrophs get their carbon from CO2 which as no hydrogen. Autotrophs get energy for catabolic reactions from inorganic chemical reactions or from sunlight.
Microbial cells are about 12% nitrogen on a dry basis. Nitrogen is needed for protein and nucleic acids. Many bacteria use NH3 as a nitrogen source. Some can use NO3-, and a very few can use N2 gas.
Phosphorous is needed for nucleic acids and phospholipids.