What are Nutrients?
Chemical substances that an organism obtains from its environment which helps in biosynthesis of other chemical substances and energy generation, thus helping the organism to grow. Nutrition is the process of obtaining nutrients.
Essential Nutrient – Any substance whether an element or a molecule, that must be provided to an organism.
Macroelements/Macronutrients
|
Element |
Cell Component | Sources | Form |
|
Carbon |
Carbohydrates, Proteins, Nucleic acids, Lipids | CO2, Carbonates, Organic matter | Organic molecules |
|
Hydrogen |
Carbohydrates, Proteins, Nucleic acids, Lipids |
Water, gas, mineral deposits, H2S, CH4 |
Organic molecules |
|
Oxygen |
Carbohydrates, Proteins, Nucleic acids, Lipids, Inorganic salts |
Air, H2O, Oxides |
Organic molecules |
| Nitrogen | Carbohydrates, Proteins, Nucleic acids, Lipids, Amino acids, Cofactors | Air, Nitrates, Nitrites, Ammonium ions, Amino acids, |
Ammonium ions |
|
Phosphorus |
Nucleic acids, ATP, Cofactors, Phospholipids and some proteins | Mineral deposits |
Phosphates (Inorganic) |
|
Sulfur |
Amino acids, Vitamin B1 (thiamine) and biotin |
Volcanic deposits (H2S, Sulfates, Sulfites, Sulfides) |
Disulfide bonds, sulfhydryl groups |
|
Magnesium |
ATP, Chlorophyll, Cofactor for enzymes, Stabilizes cell membrane and ribososmes | Mineral deposits, Geologic sediments (MgSO4) |
Inorganic (Mg2+) |
|
Potassium |
Cofactors of many enzymes including some involved in protein synthesis | Mineral deposits, Ocean (KCl, K3PO4) |
Inorganic (K+) |
|
Calcium |
Cell wall, spore coats of bacteria (heat resistance of bacterial endospores) | Mineral deposits, Ocean (CaCO3, CaCl2) |
Inorganic (Ca2+) |
|
Iron |
Cytochromes, Cofactors, other electron carry proteins | Mineral deposits, Geologic sediments (FeSO4) |
Inorganic (Fe2+, Fe3+) |
Micronutrients/Trace Elements
- They usually are a part of enzymes and cofactors
- Facilitate catalysis of reactions and maintenance of protein structure
|
Element |
Use |
|
Zinc |
Present in the active site of some enzymes Associated with regulatory and catalytic subunits (e.g., E.coli aspartate carbamoyl transferase) |
| Manganese |
Helps many enzymes catalyze the transfer of phosphate groups |
|
Molybdenum |
Nitrogen fixation |
|
Cobalt |
Component of vitamin B12 |
Growth Factors
- An organic compound such as an amino acid, nitrogenous bases or vitamins that cannot be synthesized by an organism but are essential cell components or their precursors
- Essential amino acids are those that must be obtained from food
- Fastidious organisms are those who require growth factors
- 3 major growth factors –
- Amino acids
- Purines and pyrimidines
- Vitamins
- Amino acids must be obtained for protein synthesis
- Purines and pyrimidines are needed for nucleic acid synthesis
- Vitamins are small organic molecules that usually make up all or part of enzyme cofactors and are needed in only very small amounts to sustain growth
- Haemophilus influenza grow only when hemin (factor X), NAD+ (factor V), thiamine & pantothenic acid (vitamins), uracil and cysteine are provided
- Enterococcus faecalis needs 8 different vitamins for growth
- Mycoplasma require cholesterol
- Some growth factors produced by microorganisms and are harvested for commercial production:
- Riboflavin – Clostridium, Candida, Ashbya, Eremothecium
- Coenzyme A – Brevibacterium
- Vitamin B12 – Streptomyces, Propionibacterium, Pseudomonas
- Vitamin C – Gluconobacter, Erwinia, Corynebacterium,
- Carotene – Dunaliella
- Vitamin D – Saccharomyces
Nutritional Categories
- Based on C sources –
- Autotrophs – CO2 is the sole or principal biosynthetic carbon source
- Heterotrophs – Organic forms of C becomes the source
- Based on electron donor –
- Lithotrophs – Use inorganic compounds
- Organotrophs – Use organic compounds
- Based on energy source –
- Phototrophs – Use solar energy
- Chemotrophs – Use chemical compounds
|
Type of Microbe |
Energy Source | Electron Donor | Carbon Source |
Examples |
|
Photolithoautotroph |
Light | Inorganic compounds | CO2 | H2S – Purple and Green S bacteria eg., Chlorobium, Chromatium
H2O – Cyanobacteria (Nostoc), Photosynthetic protists |
| Photoorganoheterotroph | Light | Organic compounds | CO2, mostly organic C |
Purple non-S bacteria Green non-S bacteria |
| Chemolithoautotroph | Inorganic compounds | Inorganic compounds | CO2 |
H2S – Thiobacillus H2 – Pseudomonas Nitrosomonas, Nitrococcus, Nitrobacter |
|
Chemoorganoheterotroph |
Organic compounds | Organic compounds | CO2, reduced organic C | Most pathogens and non-photosynthetic microbes, fungi, many protists and archaea |
| Chemolithoheterotroph (mixotroph) | Inorganic compounds | Inorganic compounds | CO2, reduced organic C |
S oxidizing bacteria (Beggiatoa) |