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Chapter 5 Lecture Notes: Microbial Nutrition
I. The common nutrient requirements
A. macroelements
1. major (g/L)
a) C, O, H, N, S, P
b) uses: part of proteins, nucleic acids, carbohydrates, and lipids
c) sources
(1) Carbon and oxygen frequently supplied together
(a) autotrophs = use CO2 as sole C source
(b) heterotrophs = use reduces, preformed organic
materials as C source
(2) Hydrogen
(a) lithotrophs = reduced inorganic molecules
(b) organotrophs = organic molecules
(3) Nitrogen
(a) can be part of the compounds that supply C
(b) amino acids
(c) ammonia
(d) nitrate
atmospheric nitrogen
(4) Phosphorus
(a) inorganic phosphate (PO34-)
(5) Sulfur
(a) sulfate
(b) amino acid cysteine
2. minor (mg/L)
a) K, Ca, Mg, Fe
b) uses: mostly cofactors for some enzymes and proteins
c) sources:
(1) K+, Ca2+, Mg2+ - mostly free ions and salts
(2) Fe (a) free ions
(b) iron salts
(c) bound to compounds in animal hosts (i.e. hemoglobin,
lactoferrin)
B. microelements or trace elements (µg/L)
usually metals that serve structural and catalytic roles for some enzymes
C. Growth factors = Organic compounds that are required for growth because they can
not be synthesized by a particular organism and are part of essential cell components
1. Amino acids (for proteins)
2. Vitamins (small organic molecules used as cofactors in enzymes)
3. Purines and pyrimidines (for nucleic acid synthesis)
