(3) Basic Nutritional Requirements for Microbial Growth:
• Source of Nutrients
• Source of Energy
• Source of Electrons (e-) or Hydrogen atoms that donate e-
I. Source of Nutrients / (carbon) – the basic building blocks used by microbes to
build/synthesize new cell components basic building blocks are the elements from the Periodic Table.
Macroelements – elements that are required in large amounts for growth
(make up 95% of dry cell weight – no water):
carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, iron, magnesium, sulfur
Microelements or Trace Elements – elements required for growth, but only in
very small amounts:
copper, cobalt, nickel, zinc, manganese
Classification of Microbes by Carbon Requirement:
A. Autotrophs (self-fed) – microbes use carbon dioxide (CO2) as sole source of carbon.
B. Heterotrophs (mix-fed) – microbes use many diverse organic compounds as their source of carbon (Ex. glucose, amino acids, purines, and pyrimidines).
II. Source of Energy – the capacity/ability to do work.
Work by cells may include:
A. Biosynthesis of macromolecules/new cell components
B. Active Transport
To “pay” for work, cells use ATP (Adenosine Triphosphate):
ATP ADP + Pi (phosphate group) + Energy to do work
How do cells get ATP?
ADP + Pi + Energy ATP
Where does Energy to create ATP come from?
(2) Strategies/Classification for Energy to Create ATP:
1. Phototrophs (light-fed) – microbes use energy from sunlight to create ATP through Photosynthesis.
H2O + CO2 + sunlight (energy) C6H12O6 (glucose) + O2
- Energy from sunlight converted into chemical energy, stored in bonds of glucose.
-These microbes must now convert chemical energy in glucose into more efficient high-energy bonds of ATP.
-Glucose will be oxidized (break down) and energy converted to ATP.
2.Chemotrophs (chemical-fed) – microbes use chemical...