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Types of Symbiotic Relationships
Type Population A Population B
Mutualism Benefitted Benefitted
Amensalism Harmed Unaffected
Commensalism Benefitted Unaffected
Neutralism Unaffected Unaffected
Parasitism Benefitted Harmed

When two species benefit from each other, the symbiosis is called mutualism (or syntropy, or crossfeeding). For example, humans have a mutualistic relationship with the bacterium Bacteroides thetaiotetraiotamicron , which lives in the intestinal tract. B. thetaiotetraiotamicron digests complex polysaccharide plant materials that human digestive enzymes cannot break down, converting them into monosaccharides that can be absorbed by human cells. Humans also have a mutualistic relationship with certain strains of Escherichia coli , another bacterium found in the gut. E. coli relies on intestinal contents for nutrients, and humans derive certain vitamins from E. coli, particularly vitamin K, which is required for the formation of blood clotting factors. (This is only true for some strains of E. coli , however. Other strains are pathogenic and do not have a mutualistic relationship with humans.)

A type of symbiosis in which one population harms another but remains unaffected itself is called amensalism . In the case of bacteria, some amensalist species produce bactericidal substances that kill other species of bacteria. For example, the bacterium Lucilia sericata produces a protein that destroys Staphylococcus aureus , a bacterium commonly found on the surface of the human skin. Too much handwashing can affect this relationship and lead to S. aureus diseases and transmission.

In another type of symbiosis, called commensalism , one organism benefits while the other is unaffected. This occurs when the bacterium Staphylococcus epidermidis uses the dead cells of the human skin as nutrients. Billions of these bacteria live on our skin, but in most cases (especially when our immune system is healthy), we do not react to them in any way.

If neither of the symbiotic organisms is affected in any way, we call this type of symbiosis neutralism . An example of neutralism is the coexistence of metabolically active (vegetating) bacteria and endospores (dormant, metabolically passive bacteria). For example, the bacterium Bacillus anthracis typically forms endospores in soil when conditions are unfavorable. If the soil is warmed and enriched with nutrients, some endospores germinate and remain in symbiosis with other endospores that have not germinated.

A type of symbiosis in which one organism benefits while harming the other is called parasitism . The relationship between humans and many pathogenic prokaryotes can be characterized as parasitic because these organisms invade the body, producing toxic substances or infectious diseases that cause harm. Diseases such as tetanus, diphtheria, pertussis, tuberculosis, and leprosy all arise from interactions between bacteria and humans.

Scientists have coined the term microbiome to refer to all prokaryotic and eukaryotic microorganisms that are associated with a certain organism. Within the human microbiome , there are resident microbiota and transient microbiota . The resident microbiota consists of microorganisms that constantly live in or on our bodies. The term transient microbiota refers to microorganisms that are only temporarily found in the human body, and these may include pathogenic microorganisms. Hygiene and diet can alter both the resident and transient microbiota.

Questions & Answers

Unvin Prisca the immune system
Gyabaa Reply
immune system is a complex of organ tissues and specialized cells which identify or kill the pathogens.
what is difference between bacillus and ecoil
Rymes Reply
similarities between prokaryotic cell and eukaryotic cell
Ednah Reply
Eukaryotic cells contain membrane-bound organelles, including a nucleus. ... Prokaryotic cells do not contain a nucleus or any other membrane-bound organelle. Prokaryotes include two groups: bacteria and another group called archaea.
what is different between plasma and serum?
difference between plasma and serum is that plasma is liquid n serum is fluid
what is microbiology
what is the diseases caused by the microorganisms
both cells have plasma membrane, which services as a barrier between the inside of the cell and outside. both prokaryotes and eukaryotes have ribosomes. they receive messages from messanger RNA molecules, telling them what proteins the cell needs.
Some bacteria infection
what is the name given to infection got from the hospital
Nosocomial infection
what is the apportion
what is the main functions of organelles
what is main function of right and left side of the brain.
Salifu. microbiology is the study of oganisms that are too small for the naked eyes to see. this include bacteria
Cabdi. apportion is to divide or share out
what is the parasitic helminths?
what are pathogens
Oluka Reply
any disease causing microorganism that can invade the body and cause harm
hepatitis b
what's da answer
any diseases that course harmful to body
hepatitis is usually implementery of the liver and is commonly course by virus infection
a type of virus that causes severe illness lasting from two to six weeks it may cause massive lived necrosis and cirrhosis
hepatitis B are transmitted when in contact with body fluid such as blood,semen,varginal secration that contain the hepatitis b virus
I understand necrosis,means death of all cell or injury of blood supply, but what is cirrhosis pls
sorry meant liver cirrhosis
good evening all
ok liver damage
I have a question
Hey welcome all of you...i think you are discussing about Micro-organisms..what does it Micro?
how about, scabies (bacteria) yeah can some one gist me abt it
sorry what doest it mean Micro organism?
microorganism are minute living organisms found almost everywhere. they can be autotrophic heterotrophic or chemotrophic
Tell me about enzyme kinetics
wowoww thanks a lot farmuyiwa Alice
have anyone colony pigmentation of different types of bacteria such as Aeromonas, Edwardsiella, vibros,
yes dear sadiqur Bacterias are live in everywhere.. .
microorganisms are arganism that cannot been seen with 👀 until by the use of microscope
microorganisms are arganism that cannot been seen with 👀 until by the use of microscope
yhea organisms are organisms they are naked eye/can't seen by our eyes
and scabies are one of the most common skin condition that can course itches and raches.
and also scabies are not infection, but an infestation
my Q is what is the contribution of van-leeuwenhoek in field of microbiology
Antony van leevenhoek is father of microbiology.
Anton Van leewun hook is discovered Microscope it's true or not? who can brief me please
micro organisms are organism that cannot be seen with an aided eyes ,but by the use of microscope
Yes.. He discover first microscope. He take 2 lence at a time and he saw the plant cells... Thus he was called father of microbiology
who examined water from a bathtub and discovered microbes
for instance any type of Stagnant water is creat there are d/t tupes of small animals.. so those animals are called Micro organism?
thank you javpal for Describing.
Hi the father of microbiology is Louis Pasteur
Then the father of medical microbiology is Robert Koch
can you please differentiate between vacuoles and inclusion bodies
Noor Reply
vacuoles consists of watery solution called cell sap while bodies are organelles
5 difference please
Archaea is an odd type of bacteria that live in extreme environments; high salt, high temperature etc. usually called extremophiles.
Danesia Reply
you know anyone that has delt with enterobacter agglomerans.
it is a type of gram negative bacteria and its ubiquitous mostly isolated from plant stuffs and also from faecal material of animals. I heard the name pantoea . it is bacillus in structure.
What are the classification of microorganisms
Portia Reply
Basic classification are eukaryotic and prokaryotic..
micro organisms are classified into three namely: Archaea, eukaryote and prokaryotic organisms
Yay that's right
what is archaea
I've got an issue with the message view
Frank Reply
Is there any effective way to learn microbiology.
Frank Reply
I have some basic knowledge of biology. I mean i'm totally beginner in that field.
Assuming that i'm interested in neuroscience. What is the best way to master that particular subject.
Can you wait me just a minute
Iam apologies for guidance you in neuroscience.. I'm not physician.. I'm microbiologist
My pleasure to join to you
Let's begin a conversation
Frank Reply
What would be saying
do you know anything about microbiology
I have so much studying to catch up on🙄
any study tips
Yas of course
What would you like to know
well i'm studying Pharmacy second year and i just started With Microbiology
if you have any basics to tell us 🤷🏻‍♀️ would be helpful
Yas, first you must know that you will have a very easy lecture..
In second stage you will try to learn the type of microbiology
A simple definition for microbiology
In second stage you will try to learn the type of microbiology.. you must learn the bacteria..its structure.. Classification of bacteria according to shape..
It's so easy
What triggers the natural killer cells
jenipher Reply
the immune system
microbiology is the study of science which deals with study of microorganism e.g .virus,bacteria
sufian Reply
microbiology is a branch of science that deals with invisible microorganisms.
microbiology is the branch of science which deals with the study of organisms too small to be seen with the naked eye
what is microbiology
Safwan Reply
history of microbiology
give all details about cell
Samim Reply
Practice MCQ 3

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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