Question

Classify microorganisms based on their nutrient requirements

Answer 1

Microorganisms can be classified on the basis of cell structure, cellular metabolism, or on differences in cell components such as DNA, fatty acids,pigments, antigens, and quinones.

There are seven major types of microorganisms ; Bacteria, Archaea, Protozoa, Algae, Fungi, Viruses and multicellular animal parasites(helminths).

CLASSIFICATION OF BACTERIA ON THE BASIS OF NUTRITION :-

(a) Nutrition is substances used in biosynthesis and energy production and therefore are required for all living things.

(b) Bacteria, like all living cells, require energy and nutrients to build proteins and structural membranes and drive biochemical processes.

(c) Bacteria require sources of carbon, nitrogen, phosphorous, iron and a large number of other molecules.

(d) Carbon, nitrogen and water are used in the highest quantities.

(e) The nutritional requirements for bacteria can be grouped according to the carbon source and the energy source.

(f) Some types of bacteria must consume pre-formed organic molecules to obtain energy, while other bacteria can generate their own energy from inorganic sources.

On the basis of energy source organisms are designated as :

Phototrophs:-

The organisms which can utilize light as an energy source are known as phototrophs. These bacteria gain energy from light.

Chemotrophs:-

These bacteria gain energy from chemical compounds.They cannot carry out photosynthesis.

On the basis of electron source organisms are designated as:

Lithotrophs: Some organisms can use reduced organic compounds as electron donors and are termed as lithotrophs. They can be Chemolithotrophs and Photolithotrophs.

Organotrophs: Some organisms can use organic compounds as electron donors and are termed as organotrophs. Some can be Chemoorganotrophs and Photoorganotrophs.

On the basis of carbon source bacteria may be:-

(1) All organisms require carbon in some form for use in synthesizing cell components.

(2) All organisms require at least a small amount of CO2.

(3) However, some can use CO2 as their major or even sole source of carbon; such organisms are termed as Autotrophs.

(4) Others require organic compounds as their carbon source and are known as Heterotrophs.

CLASSIFICATION OF FUNGI BASED ON MODE OF NUTRITION:-

On the basis of nutrition, kingdom fungi can be classified into 4 groups.

1. Saprophytic- The fungi obtain their nutrition by feeding on dead organic substances.

Ex:- Rhizopus, Penicillium and Aspergillus.

2. Parasitic- The fungi obtain their nutrition by living on other living organisms(plants or animals) and absorb nutrients from their host.

Ex:- Taphrina and Puccinia.

3. Symbiotic- These fungi live by having an interdependent relationship association with other species in which both are mutually benefited.

Ex:- Lichens and Mycorrhiza.

BASED ON THE MODE OF NUTRITION PROTOZOA ARE DIVIDED INTO TWO TYPES:-

1. Free living protozoa (Euglena)- The free living protozoa are those which do not infect or live on hosts for their survival. They may produce their food photosynthetically or eat bacteria, yeast and algae.

Ex- Euglena

2. Parasitic protozoa- They depend on their host for survival. They take in fluids from the body of their hosts.

Ex- Plasmodium

MODE OF NUTRITION FOR VIRUSES:-

A virus uses camouflage to trick the cell. Its capsid or receptor proteins look like nutrients the cell needs. When the virus receptor binds to the cell receptor, the cell thinks the virus is a nutrient and pulls it in.Now the cell is infected.

MODE OF NUTRITION IN ALGAE:-

All algae contain chlorophyll.Photoautotrophy is the principal mode of nutrition in algae; in other words , they are"self-feeders", using light energy and a photosynthetic apparatus to produce their own food (organic carbon) from carbon dioxide and water.

MODE OF NUTRITION IN ARCHAEA:-

Archaebacteria are microscopic organisms found in extreme places on earth. Because they are in such strange places, their nutrition is varied and complex, but often includes direct absorption, chemosynthesis, and unusual uses of the sun's light.

MODE OF NUTRITION FOR HELMINTHS:-

Helminths and multicellular eukaryotes, can either be free-living or parasitic. These parasites live in and feed on hosts which allow them to obtain nourishment while disrupting the hosts nutrient absorption. Parasitic worms are commonly found within the intestine and thus, are called intestinal parasites.