Microbial Associations in Micro Organisms | Biology Ideas


Microorganisms have Microbial Associations usually have been considered as isolated entities.

Most microorganisms live in complex communities.

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These microbial interactions and their roles in nature and disease are crucial.

Microorganisms can be physically associated with other organisms in a variety of ways.

Microbes have evolved while interacting with the inorganic world and with higher organisms, and they largely play beneficial and vital roles.

Disease-causing organisms are only a minor component of the microbial world.

Microbes also contribute to the functioning of ecosystems, or self-regulating biological communities and their physical environment.

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It defines the relationship in which some reciprocal benefit accrues to both partners.

Here the mutualist and the host are metabolically dependent on each other.

mutualism as Microbial Associations

1] The protozoan-termite relationship

These protozoans exist on a diet of carbohydrates, acquired as cellulose ingested by their host.

The protozoa engulf wood particles, digest the cellulose, and metabolize it to acetate and other products.

Termites oxidize the acetate released by the protozoans. Because the host is almost always incapable of synthesizing cellulases (enzymes that

Catalyze the hydrolysis of cellulose), it is dependent on the mutualistic protozoa for its existence.

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2] Riftia spp.

The giant, red, gutless tubeworms (Riftia spp.) takes up hydrogen sulfide from the seawater and binds to hemoglobin (the reason the worms are bright red).

The hydrogen sulfide is then transported in this form to the bacteria, which use the sulfide-reducing power to fix carbon dioxide in the Calvin cycle.

The CO2 required for this cycle is transported to the bacteria in three ways: freely dissolved in the blood, bound to hemoglobin, and in the form of organic acids such as malate and succinate.

These acids are decarboxylated to release CO2 in the trophosome, the tissue containing bacterial symbionts.

Using these mechanisms, the bacteria synthesize reduced organic material from inorganic substances.

The organic material is then supplied to the tubeworm through its circulatory system and serves as the main nutritional source for the tissue cells.



Relationship in which one symbiont, the commensal, benefits while the other (sometimes called the host) is neither harmed nor helped

This is a unidirectional process.

The spatial proximity of the two partners permits the commensal to feed on substances captured originated by the host the commensal often

Obtains shelter by living either on or in the host.

The commensal is not directly dependent on the host metabolically and causes it no particular harm.

When the commensal is separated from its host experimentally, it can survive without being provided

Some factors or factors of host origin.

Commensalism relationships between microorganisms include situations in which the waste product of one microorganisms is the substrate for another species.

1] Nitrification Process

The oxidation of ammonium ion to nitrite by microorganisms such as Nitrosomonas and the subsequent oxidation of the nitrite to nitrate by Nitrobacter and similar bacteria Nitro-bacter benefits from its association with Nitrosomonas because it uses nitrite to obtain energy for growth.


2] Non-Pathogenic strain of E-coli

It lives in the human colon, but also grows quite well outside the host, and this is a typical commensal. When oxygen is used up by the facultatively anaerobic E-Coli, obligate anaerobes such as Bacteroides are able to grow in the colon. The anaerobes benefit from the association with the host and E. coli, but E. coli derives no obvious benefit from the anaerobes. In this case, the commensal E. coli contributes to the welfare of other symbionts.


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