Nutrient requirements in Microorganisms

Nutritional requirement in
Microorganisms
Bhanu Krishan
Chandigarh University

 Nutrients
I. Types of nutrients
 Requirement for carbon, hydrogen and oxygen
 Nutritional types of microorganisms
 Requirement for nitrogen, sulphur and phosphorous
 Growth factors
Topics to be discussed

 To obtain energy and construct new cellular
components, organisms, must have a supply of raw
materials or nutrients. Nutrients – are substances
used in biosynthesis and energy production.
What are nutrients?

Macronutrients
 Macronutrients are those
nutrients which are required by
the organisms in larger quantity
as their control the major rate
for development and growth of
that particular organism. Some
of the macronutrients are
oxygen, carbon, nitrogen,
sulphur, sodium, chlorine and
phosphorous.
Micronutrients
 Micronutrients are the
nutrients which are required in
lesser quantity but are
required for specific function.
They are generally zinc,
copper, manganese,
molybdenum, nickel and
cobalt.
Besides macro and micro nutrients, some microorganisms may have
particular requirements that reflect the special nature of their
morphology or environment.
Diatoms need silicic acid to construct their beautiful cell walls of silica.
Bacteria growing in saline lakes and oceans depend on the presence of
high concentrations of sodium ion.
Microorganisms require a balanced mixture of all the above nutrients for
proper growth.

 Carbon is needed for the skeleton or backbone of all
organic molecules and molecules serving as carbon
sources normally also contribute both oxygen and
hydrogen atoms. One important carbon source that does
not supply hydrogen or energy is CO2 . Autotrophs – can
use CO2 as their sole or principal source of carbon. Many
microorganisms are autotrophic, and most of these carry
out photosynthesis and use light as their energy source.
Some autotrophs oxidize inorganic molecules and derive
energy from electron transfer. Heterotrophs – are
organisms that use reduced pre-formed organic molecules
as carbon sources.
Requirement for carbon, hydrogen
and Oxygen.

 In addition to Carbon, hydrogen and oxygen all organisms require sources
of energy and electrons for growth.
 Carbon sources:
 Autotrophs - CO2 sole or principal biosynthetic carbon source
 Heterotrophs – reduced, preformed organic molecules from other organisms.
 Energy sources:
 Phototrophs – use light as their energy source.
 Chemotrophs – obtain energy from the oxidation of chemical compounds
(either organic or in organic)
 Electron sources:
 Lithotrophs – use reduced inorganic substances as their electron source.
 Organotrophs – extract electrons from organic compounds.
Nutritional types of microorganisms

 Photoorganotrophic heterotrophy or photoorganoheterotrophy:
 Source of energy – light energy
 Source of electrons – organic hydrogen/ electron
 Carbon source – organic carbon sources (CO2 may also be used)
 Example: Purple and green nonsulfur bacteria (common inhabitants of lakes and streams)
 Chemolithotrophic autotrophs or chemolithoautotrophy:
 Source of energy – Chemical energy source (inorganic)
 Source of electrons – Inorganic hydrogen/ electron donor
 Carbon source - CO2
 Example: Sulfur-oxidizing bacteria, hydrogen bacteria, nitrifying bacteria, iron-oxidizing bacteria.
 Chemoorganotrophic heterotrophs or chemoorganoheterotrophy:
 Source of energy – Chemical energy source (organic)
 Source of electrons – Inorganic hydrogen/ electron donor
 Carbon source – organic carbon source
 Example: Protozoan, fungi, most non-photosynthetic bacteria (including most pathogens)
Nutritional types:

Nutritional types:
Cyanobacteria
Fungi
Green Sulphur
bacteria
Protozoan

 Nitrogen is needed for the synthesis of amino acids, purines, pyramidines, some
carbohydrates and lipids, enzyme cofactors and other substances. Most
phototrophs and many nonphotosynthetic microorganisms reduce nitrate to
ammonia and incorporate the ammonia in assimilatory nitrate reduction. A variety
of bacteria like many Cyanobacteria and Rhizobiium can reduce and assimilate
atmospheric nitrogen using the nitrogenase systems. Phosphorous is present in
nucleic acids, phospholipids, ATP, several cofactors, some proteins and other cell
components. All microorganisms use inorganic phosphate as their phosphorous
source and incorporate it directly. E.coli can use both organic and inorganic
phosphate. Sulfur is needed for the synthesis of substances like the amino acids
cysteine and methionine, some carbohydrates biotin and thiamine. Most of them
use sulfate as a source of sulfur and reduce it by assimilatory sulfate reduction;
a few require a reduced form of sulfur such as cysteine.
Requirements for nitrogen,
phosphorous and sulfur:

 All living organisms contain certain vitamins. These functions
either as coenzyme for several enzymes or as building block for
certain coenzymes. Some bacteria are capable of synthesizing
their entire requirement for vitamins from other compounds in
the culture medium, but others cannot do so and will not grow
unless the required vitamins are supplied.
Requirement for Vitamins and Water

 All living organism require water and in the case of bacteria all
nutrients must be in aqueous solution before they can enter the
cells. Water is highly polar compound and has ability to dissolve
cellular components. There it can be said, water provides the
suitable condition for providing required nutrients to the
microorganisms
Requirement for Water

 Many microorganisms have the enzymes and pathways
necessary to synthesize all cell components. Many lack one
or more enzymes and hence require organic compounds
because they are essential cell components or precursors
of such components and cannot be synthesized by the
organisms are called – growth factors. There are three
major classes of growth factors:
 Amino acids – needed for protein synthesis.
 Purines and Pyramidines – for nucleic acid synthesis
 Vitamins – small organic molecules that usually make up all or
part of enzyme cofactors, and only very small amounts sustain
growth.
Growth factors

 Text Books:
1. Jeffery C. Pommerville. Alcamo's Fundamentals of
Microbiology (Tenth Edition). Jones and Bartlett Student
edition.
2. Gerard J. Tortora, Berdell R. Funke, Christine L. Case.
Pearson - Microbiology: An Introduction. Benjamin
Cummings.
 Reference Books:
1. Lansing M. Prescott, John P. Harley and Donald A. Klein.
Microbiology. Mc Graw Hill companies.
References

Nutrient requirements in Microorganisms

Nutrient requirements in Microorganisms

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