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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

what are the prokaryotic
Lungu Reply
prokaraytotic is a unicellular organizm that lacks membrane bound nucleus
Zaajid
and whats eukaryotic
abdiqani
eukaryotic cell are cell which contain anuclues and organells
Zaajid
eukaryotes are the cells that have organells which are protected by membranes
maxo
Explain on the Francisco reddi did to prove the theory of spontaneous generation
Diana Reply
what is parasite
Abdirizack Reply
designing of aseptic area
Aashish Reply
I don't know
Abdirizack
what is rickettsia
DENNIS Reply
what is microbiology
Erasto
Is the science that works with microorganisms.
Rose
richettsa is small microorganisms that cause disease in human like typhus; they are like viruses that can grow only inside living cells, they're transmitted by mites, ticks or lices.
Rose
what is plasmid?
mavis
plasmid is extra chromosomal body present in bacteria...which have additional genetic functions example... antibiotic resistance genes....etc etc
Chaitanya
state the theory of spontaneous generation of micro oranisms and germ theory of disease
UKAMAKA Reply
what are the advantages of high note numerical aperture
Genius Reply
list if non flagellated pritozoa
Mepung Reply
Can someone that's understanding of the Kreb Cycle please explain & breakdown it down to me in the simplest way without giving me the dictionary version or Google version. Basically in there own words of knowledge....!
Kisha
ok
lucas
please can someone help explain positive and negative feedback in simple term
Gum
negative feedback is the arresting of reaction or reverse of the reaction according to the response and postive feed back is the direct response without reversing or arresting a reaction.
Greet
OK
umar
pls can someone explained Kinney stone in memorising in shot time
umar
what tyoebif microorganism will be killed by antibiotic trwatmeant
Mary Reply
I don't really don't understand aerobic respiration anaerobic respiration and fermentation. Can someone explain & breakdown this in the simplest way please.
Kisha
Anaerobic Respiration in which foodstuffs are partially oxidized, with the release of chemical energy, in a process not involving atmospheric oxygen, such as alcoholic fermentation, in which one of the end products is ethanol.
Muhammad
aerobic respiration A type of respiration in which foodstuffs are completely oxidized to carbon dioxide and water, with the release of chemical energy, in a process requiring atmospheric oxygen.
Muhammad
please can someone explain what pseudomonas species and biofilm is?
uju
Fermentation is the growth of cells or microorganisms in bioreactors (fermenters) to synthesize special products. Fermentation in biochemistry refers to the biodegradation of carbon compounds by cells or organisms under anaerobic (lack of oxygen) conditions.
Muhammad
Please under which conditions does pathogens become established in the human tissues and can cause diseases
Atambilla
please the life cycle of plasmodium parasite
mavis
who is John Needham
Mary Reply
John Needham is one of the researcher in microbiology. He also experimented when scientists did not believe animals could arise spontaneously ,but did believe microbes could.
Gum
okay is he late
Mary
by the way what are the list of courses offered by a newly admitted student for microbiology
Mary
Needham's experiments with beef gravy and infusions of plants material reinforced this idea.
Gum
what drugs are given to a person with Otis nerve problem(ear problem)
Gum Reply
good morning to you all.
Muhammad Reply
Dr.A.K.S.P.G. college Akbarpur Ambedkar Nagar
Rajan
Shailesh Vishwakarma BSc 1st year
Rajan
differentiate between eukaryotes en prikaryotes
AKANKWATSA Reply
eukaryotes are organisms with complex cellular structure(presence of nucleus and mitochondrial) like plants and animals whilst prokaryotes are organisms with simple cellular structure (absence of nucleus, mitochondrial) like arthropods.
Seidu
hlo
Shagufta
hii
dr
hello sir
pankaj
I am Pankaj from bihar
pankaj
I am study in NDRI karnal in btech in dairy
pankaj
I am Pankaj from bihar
pankaj
thanks am studying biomedical sciences in zambia.chikankata
Sharon
Am a studying Disease Control in Ghana(kintampo)
Seidu
I'm studying Environmental health in Zimbabwe 🇿🇼
trust
am Joyce mwale studying nursing in Lusaka Zambia
Joyce
hi pankaj
Shailesh
hi frds iam from India
Nevil
IAM studying degree (micro biology)
Nevil
Hi I am microbiologist
Muhammad
Hi friends I'm from Nigeria studying Microbiology
uju
i am biotechnologist from pakistan
Saddam
hi feds iam from india
Shibanjan
hi
Krishna
india
Krishna
hy frnds am from Uganda
AKANKWATSA
am studying nursing/midwifery n kampala
AKANKWATSA
I'm Gum Joseph Kakuu from Ghana,I'm studying RGN in nursing Jirapa.
Gum
I'm Hellen from Kenya studying applied biology
Hellen
I live in india
Krishna
am studying biotechnology
Krishna
am maryjoy uwaoma from Nigeria,I am studying microbiology in NSUKKA NIGERIA
Mary
Nice meeting You people hear
Seidu
thanks you.
Gum
can someone in there own words in the simplest way breakdown what aerobic respiration anaerobic respiration and fermentation means please and not from the dictionary version...!
Kisha
what are the cultivation and identification of microorganisms
Algel Reply
ransport media.basic culture media.enriched media..differential media .indetification media
AKANKWATSA
algel th above are some v th basic medias for bacterial growth
AKANKWATSA
factors that can Prone the host to get disease
Linda Reply
what are the factors that prones host to get disease
Linda
HELLO
Hashim
Not sure about it, can you tell us Linda?
KINGSFORD
please I want to know the factors that prones host to get disease
Linda
please Linda we have internal and external factors. internal factors are within our body cavities.eg mother having TB giving it to her child,and the others. external factors are within our surrounding environment which include our daily activities(bathing, buying food and the others)
Gum
I don't understand aerobic respiration anaerobic respiration and fermentation. Can someone that do give me a short & simple breakdown.
Kisha
pliz kisha ..aerobic respiration is th typ v repiration whre organisms use oxgyen for survival while anaerobic respiration is whre organisms survive without oxgyen at all.these use carbondioxide
AKANKWATSA
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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