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Nutritional types of bacteria.

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Introduction.

Nutrirtion are substances used in biosynthesis and energy productionand therefore are required for microbial growth .Nutrients are of two types according the demand of body.The elements like carbon, oxygen, nitrogen etc are required in larger amounts to body so they are called Macronutrients. About 95%of dry weight of cell is made up of such nutrients. Similarly, the trace nutrients except the macronutrients which are required to body are known as micronutrients.Nutrition and energy are require dto carry out cellular activity and to synthesize different cellular components. Microorganisms are also classified based on the source of energy, energy and carbon as follows:

Nutritional types of bacteria;

Phototrophs:

These bacteria gain energy from light. They are furthur divided into two groups on the basis of their electron source:

  • Photo-lithotrops: These bacteria gain energy from light and use reduced inorganic compounds such as H2S as a source of electrons. eg: Chromatium okeinii.
  • Photo-organotrophs:These bacteria gain energy from light an d use organic copounds such as Succinate as a source of electrons.eg; Rhodospirillum.

Chemotrophs:

These bacteria gain energy from chemical compounds. They cannot carry out photosynthesis.They are furthur divided into two types on the basics of electron source:

  • Chemo-lithotrophs:These bacteria gain energy from reduced inorganic compounds such as NH3 as a source of electron eg; Nitrosomonas.
  • Chemo-organotrophs:These bacteria gain energy from organic compounds such as glucose and ammino acids as a source of electrons.eg; Pseudomonas pseudoflora. Some bacteria can libve ether chemo-lithotrophs or chemo-organitrophs like Pseudomonas pseudoflora as they can use either glucos or H2 as electron source.

Autotrophs:

They use CO2 as a important source of carbon.They utilize light energy to assimilate CO2 such organisms are knows as photo-autotrophs. They are furthur divided into two types a sphoto-lithotrophic bacteria or photo-organotrophic bacteria on the basics of electron source.

Heterotrophs:

Organisms that use organic compound as a importanr source of carbon are called heterotrophs. They lack ability to fix CO2. Most of pathogenic bacteria of human beings, other plants and animals are heterotrophs. Some heterotrops have simple nutritional requirement while som eof them require large amount of vitaminand other growth promoting substance. Such organisms are called fastidious heterotrophs.

Transport/Uptake of Nutrients by microcroorganisms.

There are two methods o transport of nutrition in microorganisms they are as follows:

  • Passive and faciiate diffusion:

Glycerol can passively diffused via. cell membrane from higher concentration to lower concentration. Very small molecules like H2O, O2, CO2 etc. often moves across membrane. LArger molecules , ions and polar substances do not cross membrane by diffusion. Difusion is the compound carried by the facilitating agent is called facilatetd diffusion. The carried protein binds and transports the elements through the membrane bilayers. Transportation happens due to morphological change brought in carries protein after binding of the substance. facilitated diffusion is not found in prokaryotes except glycerol transport in few species but is frequent in eukaryotes.

  • Active trasnport:

It is the transport fro th elower concentrated region to the higher concentrated region by use of energy . Carried protein or premease binds with specific solute. Active transport has following features:

  1. It is active in bacteria, archea and eukaryotes.
  2. It helps in transport of protein and Na+gradient.
  3. group translocation eg; bacterial PTS ( transport transferase) system.
  4. It helps in uptake of iron by siderophores.

Refrences:

C.H.Collins. (1995). Microbiological Methods. Oxford Univ Press.

D.Greemwood, R. S. (2002). Medical Microbiology. London: Churchill Livingstone.

M.J.Pelezar. (1993). Microbiology. Tata McGraw hill.

M.T.Madigan, J. a. (1997). Biology of microorganisms. London: Prentice hall International Inc.

R.N.Atlas. (1984). Fundamentals and Applicatins. NewYork: MacMiHiam PUblishing Co.



Nutrition is required in bacteria to carry out cellular activity and regulate metabolism

Phototrophs gain energy from light

Chemotrophs gain energy from chemical compounds.

Autotrophs used COas source of carbon

heterotrops uses organic compound as a source of carbon.

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