Microorganisms nutritional requirements are described. All the essential nutrients are described with their role

1. NUTRITIONAL
REQUIREMENTS OF
MICROORGANISMS
By - Nisha Nikam

2. • Nutrients are substances used in biosynthesis of energy release required for
microbial growth.
• 95% of cell dry weight is made up of a few major elements:
• Macro elements - Carbon, Oxygen, Hydrogen, Nitrogen, Sulfur, Phosphorus,
Potassium, Calcium, Magnesium and iron.
• First 6 are components of carbohydrates, lipids, proteins and nucleic acids.
• Remaining four exist in the cell as cations and play a variety of roles.
• Examples- potassium(K) for activity of no. of enzymes.
• Calcium contributes to the heat resistance of bacterial endospores.
• Magnesium serves as cofactor for many enzymes, complexes with ATP and
stabilizes ribosomes and cell membranes.
• Iron is a part of cytochromes and cofactor for enzymes and electron carrying
proteins.

3. Microelements/Trace elements
 Manganese, Zinc, Cobalt, Molybdenum, Nickel and Copper
 Are part of enzymes and cofactors
 They aid in the catalysis of reactions
 Maintenance of protein structure
 Manganese – aids many enzymes that catalyze the transfer of phosphate groups
 Zinc – is present at the active site of some enzymes , also involved in the association of regulatory
and catalytic subunits
 Cobalt - component of vitamin B12
 Molybdenum – required for nitrogen fixation

4. Requirements for Carbon, Hydrogen, Oxygen and Electrons
• All organisms need carbon, hydrogen, oxygen and a source of electrons.
• Carbon – for the skeletons or backbones of all the organic molecules from
which organisms are built.
• Hydrogen and Oxygen – important elements found in organic molecules
• Electrons – for movement of electrons through electron transport chain
and during other oxidation reduction reactions can provide energy for use
in cellular work. Also are needed to reduce molecules during biosynthesis.

5. Autotrophs
• Organisms that use CO2 as their sole or principal source of carbon
• CO2 cannot supply their energy needs, so obtain energy from other sources like light
reduced inorganic molecules.
Heterotrophs
• Organisms that use reduced preformed organic molecules as their carbon source.
• Heterotrophic microorganisms have extraordinary flexibility with respect to carbon
source.
• Example – Actinomycetes :-degrade amyl alcohol, paraffin and rubber.
• Berkholderia cepacian :- use over 100 different carbon compounds.
• Leptospira :- use only long-chain fatty acids as their major source of carbon and

6. Nutritional types of Micro organisms
Sources of Carbon, Energy and Electrons
• Autotrophs – CO2 sole or principal biosynthetic carbon
source
• Heterotrophs – Reduced, preformed, organic molecules
from other organisms
Carbon Sources
• Phototrophs - Light
• Chemotrophs- Oxidation of organic or inorganic compounds
Energy Sources
• Lithotrophs – Reduced inorganic molecules
Organotrophs – Organic molecules
Electron
Sources