Bacteria have various nutritional requirements that can be classified in several ways. They require a source of energy, usually from chemical reactions or light. They also require electrons, which can come from inorganic or organic compounds. Bacteria are categorized based on their carbon source, whether they can produce their own carbon through photosynthesis or must obtain it from organic matter. They need nitrogen, usually from ammonia, nitrates or nitrogen-fixing bacteria. Minerals like sulfur, phosphorus, oxygen and trace elements are required. Vitamins may be synthesized or obtained from the environment. Water is also essential, making up most of the bacterial cell volume.

1. Presented By
M.Sc.(Ag.) Prev.
Dept. of Plant Pathology
Presentation
on
Nutritional Requirements in Bacteria
Presented To
Dept. of Plant Pathology

2. Nutritional types of bacteria
1. On the basis of source of energy
2. On the basis of source of electron
3. On the basis of carbon source
4. Nitrogen source
5. Minerals
6. Vitamins
7. Water

3. Nutritional Types of Bacteria
Nutrition- Process by which chemicals (nutrients) are required
from the environment and used for cellular activities.
All living organisms needs nutrient for growth.
1. On the basis of source of energy:
a) Chemotrophs : The organisms obtain energy from
chemical substance/reactions are known as chemotrophs.
eg. Escherichia coli.
b) Phototrophs : The organisms which can utilize light as an
energy source are known as phototrophs.
eg. Rhodospirillum rubrum.

4. 2. On the basis of Source of electron:
All organisms required a Source of electrons for their
metabolism.
a) Lithotrophs: Some organisms can use reduced inorganic
compounds as electron donors and are termed as
Lithotrophs.
There are two types-
i. Chemolithotrophs: chemical as energy+ inorganic electron
source. eg. Nitrosomonas europaea
ii. Photolithotrophs: light as energy+ inorganic electron
source. eg. Chromatium okenii

5. b) Organotrophs: Some organisms can use organic compounds
as electron donors.
There are two types-
i. Chemoorganotrophs: chemical as energy+ organic electron
source. eg. E. coli.
ii. Photoorganotrophs: light as energy+ organic electron
source. eg. Rhodospirillum rubrum.

6. 3. On the basis of carbon source: carbon required
for synthesizing cell components. Microorganism contains
about 50% C as of their dry weight and this carbon found in
their protein, fats, carbohydrates, lipids etc.
a) Autotrophs: These bacteria synthesize all their food from
inorganic substances (H₂O , C0₂ , H₂S salts). eg.
Chromatium okenii.
The autotrophic bacteria are of two types :
i. Photoautotrophs: light as energy+ CO2 as carbon source.
Green sulphur Bacteria
Purple Sulphur Bacteria

7. Purple Sulphur Bacteria: These bacteria have the pigment
bacteriochlorophyll located on the intracytoplasmic
membrane. These bacteria obtain energy from sulphur
compounds e.g., Chromatiiun. Theopedia rosea,
Thiospirilium.
Green Sulphur Bacteria: These bacteria use hydrogen
sulphide (H2S) as hydrogen donor. The reaction takes place in
the presence of light and pigment termed as bacteriovirdin or
bacteriopheophytin or chlorobium chlorophyll e.g.,
Chlorobium limicola, Chlorobacterium etc.

8. ii. Chemoautotrophs: These bacteria do not require light and
pigment for their nutrition. This reaction releases the energy
which is used to drive the synthetic processes of the cell.
Sulphomonas (Sulphur bacteria): These bacteria obtain energy
by oxidation of elemental sulphur. eg. thiobadllus.
Hydromonas (Hydrogen bacteria): These convert hydrogen into
water, eg. Bacillus pantotrophus.
Ferromonas (Iron bacteria): These bacteria inhabit water and
obtain energy by oxidation of ferrous compounds into ferric
forms. eg. Ferro bacillus.

9. Methanomonas (Methane bacteria): These bacteria get their
energy by oxidation of methane into water and carbon dioxide.
Nitrosomonas (Nitrifying bacteria): These bacteria get their
energy by oxidation of ammonia and nitrogen compounds into
nitrates. eg. Nitrosomonas oxidises NH3 to nitrites. Nitrobacter
converts nitrites to nitrates.
Carbon Bacteria: These bacteria oxidizes CO into CO2 e.g
Bacillus

10. b) Heterotrophic bacteria: These bacteria are pigmentless
and cannot make their own food. They obtain their food
from various types of hosts or dead organic matter. These
bacteria are of three types.
i. Photoheterotrophs: These bacteria can utilize light
energy but cannot use CO₂ as their sole of carbon. They
obtain energy from organic compounds to satisfy their
carbon and electron requirements. Bacteriochlorophyll
pigment is found in these bacteria e.g Rhodospirillum,
Rhodomicrobium etc.

11. ii. Chemoheterotrophs: Chemoheterotrophs obtain both
carbon and energy from organic compounds such as
carbohydrates, lipids and proteins. There are three
main categories that differ in how chemohetrotrophs
obtain their organic nutrients.
 Saprophytic bacteria
 Parasitic bacteria.
 Symbiotic bacteria.

12.  Saprophytic bacteria: Saprophytic bacteria obtain their
food from the dead organic matter such as leaves, fruits,
vegetables etc. eg. Acetobacter etc.
 Parasitic bacteria: These bacteria obtain their nutrition from
the tissues of the hosts on which they grow. They may be
harmless or may cause serious diseases. Parasitic bacteria
which cause pathogens. e.g. Pseudomonas citri etc.
 Symbiotic bacteria: live in close association with other
organisms as symbionts. They are beneficial to the organisms.
The common examples are the nitrogen-fixing bacteria.
e.g. Rhizobium, Ctostridium etc.

13. 4. nitrogen source
 Nitrogen used for synthesis of proteins(amino acid), DNA,
RNA, ATP etc.
 Nitrogen, nitrates, ammonia organic nitrogen campounds are
used as nitrogen source for bacteria.
 Rhizobium and Azotobacter: these are the bacteria obtain
nitrogen directly from atmosphere(soil).

14. 5. minerals
a. Sulfur: utilizes for sulfur containing amino acid (cystine,
methionine) & vitamins, sulfates, H2S used as sulfur
source.
b. Oxygen: source of oxygen may be water, molecular oxygen
or from other oxygen containing nutrients.
c. Phosphorus: phosphorus needed for nucleic acid synthesis
and formation of phospholipids, DNA, RNA, ATP etc.
phosphate ions are the primary source of phosphorus for
bacteria.
d. Trace element: for growth bacteria requires metals ions
like potassium, magnesium, calcium, iron used as cofactors
in enzyme reactions

15. 6. Vitamins:
Vitamins functions as coenzymes or building blocks for
co-enzymatic reactions of bacteria.
eg. Thiamine (B1) need for B. anthracis.
some bacteria synthesize vitamins some not depends on the
host for vitamin requirements.
7. Water:
Major essential nutrients as it accounts for about 80-90% of
total weight of cells. Hydrogen and oxygen derived
metabolically from water.

16. https:/www.researchgatenet
George N. Agrios ,Plant Pathology(5th edition 2005)
Abigali A. Salayers and Dixie D. Whitt, Bacterial
Pathogenesis A Molecular Approach ( 2nd edition)

17. Thank you....