Nutrition of Bacteria

Nutrition of Bacteria

Nutrition of Bacteria: Bacteria primarily rely on autotrophic and heterotrophic nourishment. Heterotrophic bacteria rely on the food produced by other species, whereas phototrophic bacteria synthesize their own food using a variety of colors. The host cell provides the nutrients and other necessities for parasitic microorganisms. To learn more about bacterial nutrition and the specific form of bacterial feeding, see this article.

Prokaryotic creatures like bacteria need food and energy to grow and develop, just like other living things do. For their biochemical operations, they need carbon, hydrogen, oxygen, nitrogen, metals, and water.

Classification of Bacteria on the basis of Nutrition

  • All living creatures need nutrition since these ingredients are employed in biosynthesis and energy generation.
  • In order to produce proteins, maintain structural membranes, and drive biochemical processes, bacteria require food and energy, just like all other living cells do.
  • Sources of carbon, nitrogen, phosphorus, iron, and a vast number of other chemicals are needed for bacteria.
  • The most is utilized in terms of carbon, nitrogen, and water.
  • The carbon source and the energy source can be used to categories the nutritional needs for bacteria.
  • Energy may be produced by certain bacteria using inorganic sources, whereas other bacteria must consume already-formed organic molecules.

Nutritional Types of Bacteria

Depending on their source of energy, organisms are classified as:


  • Phototrophs are creatures that can use light as a source of energy. These microbes use light to generate energy.


  • Chemical substances provide energy to these microorganisms. They are unable to perform photosynthesis.

Depending on their electron supply, organisms are classified as:


  • Lithotrophs are creatures that can utilize reduced organic molecules as electron donors.
  • Both chemolithotrophs and photolithotrophs are possible.


  • Organotrophs are creatures that can utilize organic substances as electron donors.
  • Some of them could be phot organotrophs and chemoorganotrophs.

Bacteria therefore can be either:

  • These bacteria, known as photo-lithotrophs, obtain their energy from light and obtain their electrons from reduced inorganic substances like H2S. such as Chromium konini.
  • Photo-organotrophs: These bacteria utilize organic substances like succinate as a source of electrons and obtain their energy from light. Such as Rhodospirillum.
  • Chemo-lithotrophs: These bacteria use reduced inorganic substances like NH3 as a source of electrons to produce energy, such as Nitroso monas.
  • Chemo-organotrophs: These microorganisms obtain their electrons from organic materials like glucose and amino acids. Consider Pseudomonas pseudo flora.
  • Chemo-organotrophs: These microorganisms obtain their electrons from organic materials like glucose and amino acids. Consider Pseudomonas pseudo flora.
  • Like Pseudomonas pseudo flora, certain bacteria may exist as either chemo-lithotrophs or chemo-organotrophs because they can use either glucose or H2S as an electron source.

According to the carbon source, bacteria might be:

  • For usage in synthesizing cell components, carbon is necessary for all organisms in some form.
  • Every living thing needs some CO2, at least in modest amounts.
  • However, certain organisms—known as autotrophs (autotrophic bacteria)—can use CO2 as their primary or even exclusive source of carbon.
  • Others, known as heterotrophs (heterotrophic bacteria), need organic substances as their carbon source.

Autotrophic Bacteria

Autotrophic bacteria

These bacteria produce all of their sustenance from inorganic materials (such as salts of H2S, C02, and water).

There are two categories of autotrophic bacteria:

(i)  Photoautotrophs

  • These microorganisms absorb solar energy and convert it into chemical energy.
  • CO2 is transformed into carbs throughout this process.
  • Water serves as the hydrogen donor, and the reaction yields free oxygen.
  • The primary purpose of photoautotrophs, such as cyanobacteria, which have chlorophyll pigment in their cells, is to collect sunlight.
  • Some anaerobe photoautotrophic bacteria include the pigments bacteriovirdin and bacteriochlorophyll, respectively.

Purple Sulphur Bacteria:

These bacteria have the bacteriochlorophyll pigment, which is found on the thylakoids of the intracytoplasmic membrane. These bacteria use Chromatin and other Sulphur compounds as fuel. Thiospirilium, Theopedia rose.

Green Sulphur Bacteria:

Hydrogen supplied (H2S) is used by these bacteria as a hydrogen donor. The reaction occurs when light and a pigment known as bacteriovirdin, bacteriopheophytin, or chloronium chlorophyll, such as Chloronium limicoline, Chlorobacterium, etc., are present.

These microorganisms get hydrogen from sulphides and thiosulfates, two inorganic sources. Consequently, these microorganisms are also referred to as photolithographs.

(ii) Chemoautotrophs

  • These bacteria can survive without light because they contain color and the dark phase of photosynthesis, which is what they lack in the light phase.
  • These bacteria use oxygen from the atmosphere to oxidize certain inorganic materials.
  • The energy (exothermic) released by this reaction is utilized to power the cell’s synthesis operations.

Sulphomonas (Sulphur bacteria):

These bacteria, such as Thiobacillus and Beggiatoa, produce energy by the oxidation of elemental Sulphur or H2S.

  • Elemental Sulphur Oxidizing Bacteria: Thiobacillus denitrificans is one of the sulfur-denitrifying bacteria that converts elemental Sulphur to sulfuric acid.
  • 3O2 + 2S + 2H2O + 126 kcal = 2H2SO4.
  • Supplied oxidizing bacteria, such as Beggiatoa, oxidize H2S and release Sulphur.
  • 2H2O + 2S + 141.8 Cal = 2H2S + 4O2

Hydro monas (Hydrogen bacteria)

  • These, such as Bacillus pantotrophus and Hydrogen monas, transform hydrogen into water.

2H2 + O2 2H2O + 55 kilocalories.
2H2O + CH4 + Energy = 4H2 + CO2

Ferro monas (Iron bacteria):

  • These microorganisms live in water and produce their energy by oxidizing ferrous compounds into ferric forms. Ectothrix, for instance, or Thiobacillus ferroxidase.
    Fe (OH)3 + Fe (Co)2 + 4CO2 + 81 kcal = 4FeCo3 + 6H2O + O2.

Methenolones (Methane bacteria):

  • Methane is converted by these bacteria into water and carbon dioxide to provide energy.

Nitroso monas (Nitrifying bacteria):

  • These bacteria produce nitrates by oxidizing ammonia and nitrogen molecules.
  • NH3 is converted to nitrites by Nitroso monas. Energy = NH3 + 12O2 ® H2O + HNO2
  • Nitrites are changed into nitrates by Nitrobacteria. Energy + NO2 + 12O2 ®

Carbon Bacteria:

These bacteria, such as Bacillus oligocarbophillous and Oligotroph carboxydovorans 2CO + O2 2CO2 + Energy, oxidize CO into CO2.

Heterotrophic Bacteria

Heterotrophic nutrition in bacteria
  • The organic materials, whether alive or dead, are where the heterotrophic bacteria get their ready-made meal.
  • Heterotrophs make up the majority of harmful bacteria found in humans, other plants, and animals.
  • While some heterotrophs only need basic sustenance, others need vast amounts of vitamins and other substances that promote development. Fastidious heterotrophs are the name given to such creatures.
  • Three categories of heterotrophic bacteria exist:

a. Photoheterotrophs

  • Although these bacteria can use light energy, they are unable to utilize CO2 as their exclusive carbon source.
  • To meet their needs for carbon and electrons, they extract energy from organic substances. These bacteria contain the pigment known as bacteriochlorophyll.
  • g., Purple non-sulfur bacteria (Rhodopseudomonas palustric, Rhodomicrobium).

b. Chemoheterotrophs

  • Chemoheterotrophs rely on organic substances including proteins, lipids, and carbohydrates for both carbon and energy.
  • Chemoheterotrophs rely on organic substances including proteins, lipids, and carbohydrates for both carbon and energy.
  • Energy + CO2 + H2O + Monosaccharide or Glucose + [(CH2O)n]
  • Energy + CO2 + H2O + Monosaccharide or Glucose + [(CH2O)n]

Chemoheterotrophs may be divided into three primary groups based on how they receive organic nutrients:

  • Saprophytic microorganisms.
  • Parasitic microorganisms.
  • Symbiotic bacteria.

i) Saprophytic bacteria

  • Saprophytic bacteria feed on dead organic matter that has begun to decompose, such as humus, leaves, fruits, vegetables, meat, and animal faces.
  • Enzymes are secreted by these microorganisms to break down and absorb the meal.
  • Enzymes are released to convert complicated substances like protein and carbohydrates into more readily absorbed, simpler soluble substances.
  • Examples include Acetobacter, Bacillus mycoides, and B. ramous.

ii) Parasitic bacteria

  • The tissues of the hosts that these bacteria are growing on provide them with food.
  • They could be healthy or they might spread dangerous infections.
  • Pathogens include parasitic bacteria like Bacillus typhus’s, Bacillus anthracis, Bacillus tetani, Bacillus diplheriae, Bacillus tuberculosis, Bacillus pneumoniae, Vibrio cholerae, Pseudomonas citric, etc. that cause a variety of illnesses in both plants and animals.

iii) Symbiotic bacteria

  • Symbionts, or close companions of other species, are symbiotic microorganisms.
  • They are advantageous to the living things.
  • The nitrogen-fixing bacteria, such as Rhizobium, Clostridium, Rhizobium spp., Bacillus radicicol, and B. azotobacterial, are typical examples.
  • These microorganisms are found in the roots of legume plants.
  • These bacteria convert the free nitrogen in the atmosphere into nitrogenous chemicals that the plants can use. In exchange, the bacteria receive nourishment and defense from the plant.

The human microbiota

A typical adult has a microbial biomass of around 0.2 kg and is home to hundreds of different bacterial species . The human microbiota is made up of bacteria and other microorganisms found in the body, including viruses and fungus. The majority is found in the gastrointestinal system, although bacteria are present on all surfaces that come into touch with the outside world, including the skin, upper respiratory tract, and genital tract. As explained in this video, the microbiota coexists with the human host and serves a variety of crucial purposes.

Most bacteria are good for us

To mention a few functions, the bacteria in our systems help break down the food we eat, assist us access nutrients, and neutralize toxins . Additionally, by shielding colonized surfaces from encroaching pathogens, they contribute significantly to the fight against infections.

The word “microbiome” is frequently used to refer to both microorganisms and their DNA genomes. The number of studies on the human microbiome has risen recently. Microbes are crucial to both disease development and human health, as is becoming increasingly clear. Obesity, gastric ulcers, colon cancer, and inflammatory bowel disease are a few illnesses for which the makeup of the microbiota has been shown to have a role.

Other microbiomes

Animals and other environments on Earth have microbiomes in addition to humans. Similar to humans, animals have microbiomes that are vital to their survival and daily activities. The soil, sediments, and oceans contain the microbes that have the greatest impact on life as we know it. These perform the well-known tasks of giving plants nutrients like nitrogen and phosphorus as well as producing growth hormones. They support the structure of the soil and the natural processes by digesting dead organic debris.

other microbiomes

Effects of Antibiotics on the Microbiome

All antibiotics have an impact on and kill pathogens at the infection site as well as germs that are naturally present in the body. This may result in a number of diseases and unintended side effects, which should deter us from using antibiotics when not necessary. For instance:

  • Decreased diversity

Antibiotic exposure has the potential to alter and/or destabilize (dysbiosis) the human microbiota. The makeup and diversity of the microbiota may be disrupted, which can result in illnesses that aren’t always directly brought on by a particular pathogen .

  • Selection of resistant bacteria

Any bacteria that are resistant to an antibiotic acquire an advantage whenever a colony of bacteria is exposed to it. The number of resistant bacteria may rise when more common microorganisms perish. Thus, widespread use of antibiotics promotes the development of resistant bacteria, which can then proliferate and result in illnesses that are challenging to treat.

Disadvantages of bacteria:

  • Typhoid, cholera, and other illnesses are all brought on by bacteria.
  • They cause food to deteriorate.
  • They cause the surroundings to smell bad when they breakdown food.
  • A disease that affects humans, animals, and plants is the main drawback.
  • Teeth are harmed by it.
  • They are a catalyst for the transformation of illness.
  • They eat unclean stuff.
  • They obliterate foodstuffs.

Harmful Bacteria

The following is a list of the bacteria and viruses that are most frequently responsible for illnesses, hospitalizations, or fatalities in the US:

  • Campylobacter.
  • Clostridium perfringens.
  • E. coli.
  • Listeria.
  • Norovirus.
  • Salmonella.


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