microbial interaction between human and microbes or microbial interaction between microbes

Microbial interaction between microbes human animal and plants download pdf file for presention or microbial interaction .pdf file 

interaction of microbes


ü Introduction about interaction
ü Possible interaction
ü Type of interaction
a. positive
b. negative
ü Human microbial interaction with example
ü Animal microbial interaction with example
ü Microbial - microbial interaction with example
ü Merit and demerit of interaction with example
ü Conclution
ü Bibliography
Microbial interaction are crucial for a successful establishment and maintenance of a microbial population  . These interaction occur by the environmental recognition  to allowed by tranfernance of microbial and genetic information. These mechanism allow microorganism to establish in a community which depending on the multi-tropic interaction could result in high diversity. Organisms living together in a community influence each other directly or indirectly under natural conditions. All the vital process of living such as growth, nutrition and reproduction requires such interactions between individuals in the same species (intraspecific) or between species (interspecific) These inter or intra relationships of individuals in a population or community of an ecosystem is called biological interactions or population interactions. The interaction between organisms may not be always beneficial to all the interacting counter parts. Based on whether, the interaction is beneficial to both interacting species or harmful to at least one interaction species, the ecological of biological interactions are classified into two categories.
Types of intraction
(I).   Positive interactions
(II). Negative interactions
(I). Positive interactions:
In positive interactions, the interacting populations help one another. The positive interaction may be in one way or reciprocal. The benefit may be in respect of food, shelter, substratum or transportation. The positive association may be continuous, transitory, obligate or facultative. The two interacting partners may be in close contact in such a way that the tissues intermixed with each other; or they may live within a specific area of the other; or attached to its surface.  Different types of positive population interactions are:
(1). Mutualism
(2). Commensalism
(3). Proto-cooperation

(1). Mutualism:
Mutualism, also called as symbiosis, is also a positive type of ecological interaction. Mutualism is a symbiotic association between two organisms in which both the interacting partners are mutually benefitted. Mutualism is different from proto-cooperation in the sense that mutualism is obligatory and none of the partners of mutualism can survive individually. In mutualism, the organisms enter into some sort of physical and physiological exchange.

Examples of mutualism:
 (a). Lichens: lichens are the symbiotic association between algae and fungi. The body of lichen composed of fungal matrix in which the algal cells are embedded. The fungi provide protection to algal components and also provide moisture and nutrients to them. The algal components in turn will supply carbohydrates for fungus.
(b). Symbiotic nitrogen fixation: mutualistic interaction can be seen in the symbiotic nitrogen fixation of Rhizobium associated with root nodules of leguminous plants is the best example. Similarly other microorganisms associated with plants such as Alnus, Casuarina, Cycas for nitrogen fixation are also belongs to mutualism.
(c). Mycorrhizae: they are the symbiotic association between fungi and the roots of some trees. Fungal components help in the absorption of water and minerals by the plant. The plant in turn supplies foot to fungal components.
(d). Pollination by animals: Bees, moths, butterflies etc. derive food from the nectar of plants and in return bring out pollinatio
 (e). Seed dispersal by animals: Fruits are eaten by birds, and other animals and the seeds contained in them are dropped in the excrement at various places.
 (2). Commensalism:
Commensalism is a positive type of ecological interaction between two species in an ecosystem.  In commensalism, the association occurs between members of two different species where one species is benefited the other is neither benefited nor harmed. Here the two populations live together without entering into any kind of physical exchange, and one is benefited without any effect on the other.
Examples of commensalism:
(a). Climbers and lianas such as Bauhinia, Tinospora etc., which are rooted in the soil but climb over large trees. These climbers use other trees as support to get enough sunlight, more than that, the supporting plants do not have any positive or negative effect.
 (3). Proto-cooperation:
Proto-cooperation is a positive type of population interaction and it is also called as non-obligatory mutualism. Proto-cooperation is a less extreme type of population interaction. In proto-cooperation, two species interact favourably with each other, though both of them are able to survive separately. It is a temporary association where both the interacting partners get benefited. It is different from mutualism in the sense that, the association is not essential for the survival of any of the species.
Example for proto-cooperation: Association between hermit crab (Eupagurus prideauxi) and sea anemone. The sea anemone is carried by the carb to fresh feeding sites and the crab is in turn protected from enemies by sea anemone.
(II). Negative interactions:
In negative interactions, one of the interacting populations is benefited and the other is harmed. In negative interaction one population may eat members of the other population, compete for foods or excrete harmful wasters. Different types of negative population interactions are:          
(1). Ammensalism
(2). Parasitism
(3). Predation
(4). Cannibalism
(5). Competition
(1). Ammensalism:
Ammensalism is a negative type of population interaction. In ammensalism one species is harmed or inhibited other is neither benefitted nor harmed. Some authors prefer to use the term antibiosis for commensalism. Antibiosis is the partial or complete inhibition or death of one organism by another through the production of some substances or environmental conditions as a result of its metabolic pathway.  In antibiosis none of them derives any benefit. The process of antibiosis is common in microbial populations and the chemical substances produced by microbes for antibiosis are generally called as antibiotics.
Examples of ammensalism
(a). Chlorella vulgaris produces a toxin (chlorellin, an antibiotic) which is harmful to other algae.
(b). Larger and more powerful organism excludes another organism from its source of shelter or food is also a type of ammensalism
 (2). Parasitism:
Parasitism is a negative type of population interaction. Parasitism belongs to the ‘exploitation’ category of negative population interactions. In exploitation, one species harms the other by making its direct or indirect use for shelter or food. A parasite is the organism living on or in the body of another organisms and deriving food form its tissues. The harmed one is called host, the benefitted one is called parasite. A parasite usually takes a host which is usually larger than its body size. Usually a specialized parasite does not kill the host at least until it has completed its reproductive cycle. Those organisms which derive their nourishment only partly and remain in contact with their host only for a short period of their life cycle are not true parasites (examples: mosquitos). Some parasites requires more than one host to complete its life cycle and such parasites are called heteraceous parasites (example Puccinia, Malarial parasite).
Examples of parasitism:
(a). Cuscuta is a total stem parasite which lives on the surface of other large plants. They are devoid of chloroplasts and hence they cannot prepare their own food. Thy have specialized absorptive structures called haustoria. In the case of complete parasite, the haustoria will be inserted into the phloem tissue of host plants and they absorb the prepared food materials from the host phloem.
 ( b). Microorganisms such as bacteria, virus, fungi, mycoplasma, protozoans etc. which cause many diseases in human and other animals and plants are parasites.
 (3). Predation:
Predation is a negative type of population interaction and it belongs to the ‘exploitation’ category of negative population interactions. In predation, one species kill and feeds on another species. The killer species is called predator and the one who dead are called prey. The predators are usually larger and power-full than prey. Predation is very important in community dynamics and it helps to maintain the constancy of number of different trophic levels in the ecosystem and thereby maintain the stability of ecosystem.
Examples of predation
(a). Lion, tiger and Beer are predators of forest ecosystem. They predate herbivores
(4). Cannibalism
Cannibalism is a negative type of interaction of individuals in the same population. In cannibalism, bigger individual of a species kill and feeds on smaller individual of same species. Cannibalism is a natural method of population control in the ecosystem.
(5). Competition
Competition is the association of two or more species; each species is adversely affected by the presence of other species in respect of food, shelter, space, light etc. Competition occurs when individuals attempt to obtain a resource that is inadequate to support all the individuals seeking it or even if the resources are adequate individuals harm one another in trying to obtain it. The resources in the environment for which the individuals compete include raw materials for life such as water, light and nutrients, space for occupying and selection of mates for sexual reproduction. The competition in the ecosystem may be of two types:
a.      Intraspecific competition
b.      Interspecific competition
(a). Intra-specific competition: It is the competition occurring between the individuals of the same population (competition within population). It is also called as scramble competition. Intra-specific competition is an important density dependent factor regulating population size. Intra-specific competition is also responsible for the even distribution of individuals of the species in an ecosystem.
(b). Inter-specific competition: It is the competition occurring between populations of different species whose requirements are common and inadequate in the ecosystem (competition between population). It is also called as contest or interference competition.

Human microbial interaction with example
The human microbiota is the aggregate of microorganismsthat resides on or within any of a number of human tissues and biofluids, including the skin, mammary glands, placenta, seminal fluid, uterus, ovarian follicles, lung, saliva, oral mucosa, conjunctiva, biliary and gastrointestinal tracts. They include bacteria, archaea, fungiand viruses (bacteriophages). Though micro-animalsalso live on the human body, they are typically excluded from this definition. The human microbiome refers specifically to the collective genomesof resident microorganisms.
Example ­-Human health Tuberculosis (TB) is a potentially serious infectious disease that mainly affects your lungs. The bacteria that cause tuberculosis are spread from one person to another through tiny droplets released into the air via coughs and sneezes.


Although your body may harbor the bacteria that cause tuberculosis, your immune system usually can prevent you from becoming sick. For this reason, doctors make a distinction between:
  • Latent TB. In this condition, you have a TB infection, but the bacteria remain in your body in an inactive state and cause no symptoms. Latent TB, also called inactive TB or TB infection, isn't contagious. It can turn into active TB, so treatment is important for the person with latent TB and to help control the spread of TB. An estimated 2 billion people have latent TB.
  • Active TB. This condition makes you sick and can spread to others. It can occur in the first few weeks after infection with the TB bacteria, or it might occur years later.
Signs and symptoms of active TB include:
  • Coughing that lasts three or more weeks
  • Coughing up blood
  • Chest pain, or pain with breathing or coughing
  • Fatigue
  • Fever
  • Night sweats
  • Chills
  • Loss of appetite
                                                                                                                M. tuberculosis (stained red) in sputum
Tuberculosis is caused by bacteria that spread from person to person through microscopic droplets released into the air. This can happen when someone with the untreated, active form of tuberculosis coughs, speaks, sneezes, spits, laughs or sings.
Although tuberculosis is contagious, it's not easy to catch. You're much more likely to get tuberculosis from someone you live with or work with than from a stranger. Most people with active TB who've had appropriate drug treatment for at least two weeks are no longer contagious.
Animal microbial interaction with example                                                   Microbiology of the rumen consists of bacteria, fungus and protozoa. Bacteria can be grouped according to their shape, size and structure and also they are grouped eight according the type of substance fermented, they contribute 1010-1011gm/cells of the rumen. These groups utilize cellulose, hemicellulose, starch, sugars, immediate acids, protein and lipids to produce methane. These groups of bacteria are liable for all fermentation process in rumen; they remove hydrogen by the reduction of carbon dioxide to produce methane which helps methionic bacteria to increase the growth of other bacterial colonies. Protozoa is about 105 to 106 cells/gram of rumen contents and fungi contribute 8%, anaerobic fungi are the predominant one.
Protozoa act as a source of protein by ingest bacteria and also act as a stabilizing factor for fermentation end products. Bacteria and fungi helps in fiber digestion and anaerobic fungi degrading cellulose and xylene, to indicate their role in fiber digestion. Microbes located in rumen mainly cover three phases, Liquid phase: occurs free living organism present in rumen fluid which feed carbohydrate and protein, it contributes about 25%.
Solid phase: Microbial group attached with food particles helps to digest insoluble polysaccharides like starch, fiber and less soluble proteins. It contributes 25% of microbial mass.
Last phase: 5% of microorganisms either attached to epithelial cells in the rumen or to protozoa.
ruminant digestion1.Grass boluses (food balls), move from mouth, down the o esophagus, to the rumen. Rumen is a large fermentation chamber (approximately 125 litres in adult cattle), with textured surface and lined with papillae. Large number of micro-organisms survive in rumen mainly bacteria which secretes enzymes for cellulose digestion. Internal pH, temperature, and microbial population (1010 per ml) soften and ferment the cellulose-rich diet of grass. 

2. Food enters the
 reticulum where further symbiotic prokaryotes and ciliated protista further digest the cellulose fibers. Due to the continuous build-up of internal gases from microbial action, ruminants belch and regurgitate their 'cud'.

3. Cud is chewed and swallowed again to enter the
 omasum. A high surface area provided by this organ removes most remaining water.

4. Fermented cellulose now enters the
 abomasum, the ruminants fourth 'stomach'. The cattle's own enzymes now digest and absorb remaining nutrients. Thanks to microbial action, ruminants absorb more nutrients than grass actually contains.

              Microbial-Microbial interaction with example

Microbial Interactions

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

Ectosymbiosis -microorganism remains outside the other organism

Endosymbiosis -microorganism is found within the other organism

Ecto/endosymbiosis -microorganism lives both on the inside and the outside of the other organism


An obligatory association that provides some reciprocal benefit to both partners (some examples are given below)                                                                                                                                                                                        Protozoan-termite relationship-protozoa live in the guts of insects that ingest but cannot metabolize cellulose; the protozoa secrete cellulases, which metabolize cellulose, releasing nutrients that the insects can use.



The microorganism (commensal) benefits, while the host is neither harmed nor helped; often the microorganism shares the same food source with the host

Occurs in situations in which waste products of one microorganism serves as the substrate for another; also occurs in situations where one microorganism modifies the environment making it better suited for another microorganism (examples are below)

Nitrification-requires the activity of two different species; one oxidizes ammonia to nitrite and the other oxidizes nitrite to nitrate.


1)They help in production of food materials such as bread, cheese, curd,etc.
2)Helps in preparation of vaccine.
3) Helps in fermentation.4) Serves as an important part of carbon and nitrogen cycle.


1) Responsible for rotting of food.
2) responsible for tooth decay.
3) They spread diseases.
4) Are somtimes responsible for whooping of plants

Some microbes are good for animal and some are bad for animal because some produces disease and some help us to prevent from disease microbial interaction is very important for environment  because they are necessary for conversion of energy and converts complicated carbonic matter to simple form of carbon so microbial interaction are necessary for living organism.

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2.      Hamilton WD. 1964. The genetical evolution of social behavior, I&II. J. Theor. Biol. 7:1–52.
3.      Sachs JL et al. 2004. The Evolution of Cooperation. The Quarterly Review of Biology 79:135-160. doi: 10.1128/mBio.00099-12
4.      Guimarães, P. R., Pires, M. M., Marquitti, F. M. and Raimundo, R. L. 2016. Ecology of Mutualisms. eLS. 1–9. doi: 10.1002/9780470015902.a0026295
5.      Neilands JB. Siderophores 1995. Structure and function of microbial iron transport compounds. J. Biol. Chem. 270:26723–6. 7. doi: 10.1074/jbc.270.45.26723