Flashcards in Lecture 12 - Microbe-Microbe Interactions Deck (57)
In terms of microbe-microbe interactions, what can change the interactions between species from (for example) commensalism to syntrophism?
changing the conditions of the environment
What are the 3 characteristics of microbe-microbe interactions?
complex, dependent on organisms, specific environment is important
What are the 4 positive cell-to-cell interactions?
(CMSS) = commensalism, syntrophism, symbiosis, mutualism
What are the 4 negative cell-to-cell interactions?
(CPAP) = competition, predation, antagonism, parasitism
What is neutralism?
no interaction, neither species are affected but live at same area
What is mutualism/symbiosis?
interaction is needed to survive in the habitat and specific species are required; both species benefit
What is syntrophism (synergism)?
growth of one is improved by another and both species benefit | basically working together
What is commensalism?
one benefits and the other is not harmed nor helped
What is competition?
organisms in the environment fight over limiting nutrient, both species are potentially harmed
What is parasitism/predation?
host is usually harmed while other is benefited
What is amensalism (antagonism)?
bacteria and fungi produce chemicals that inhibit the growth of other microorganisms
What is an example of mutualism and symbiosis interactions? Name 2 discussed.
Lichens, mycorrhizae, root nodules AND bacteria associated with insects
What is an example of syntrophism interactions? Name 2 discussed.
interspecies hydrogen transfer and cross-feeding of acetate between bacterial species
What is an example of commensalism interaction? Name 1 discussed.
nitrification — with Nitrosomonas and Nitrobacter >> NH3 = NO2 = NO3
What is an example of competition interaction? Name 1 discussed.
Soil bacteria compete with fungi for nutrients
What is an example of parasitism/predation interaction? Name 1 discussed.
Bdellovibrio require gram– bacteria host for growth
What is an example of amensalism interaction?
when end products of a species' metabolism inhibit the growth of another species (ie antibiotics)
Explain the symbiotic relationship between diatoms and cyanobacteria. Who provides what?
Diatoms turn CO2 into sugars via photosynthesis for cyanobacteria IN TURN cyanobacteria fix N2 into NH3 for diatom
How do cyanobacteria infect other diatoms?
reinfection with cyanobacteria = rare so they are inherited vertically
Where are the cyanobacteria located on the diatoms?
Can exists intracellularly or extracellularly on the diatom
Where are cyanobacteria more stably located on the diatoms and why?
intracellularly because if extracellularly, they would be easily knocked off the diatom
Explain the mutualistic relationship between cyanobacteria and fungi. Who provides what?
fungi provides UV protection to the cyanobacteria IN TURN cyanobacteria photosynthesizes for the gungi
What is a lichen and where are they usually found?
the result of the interaction between fungi and cyanobacteria; they live in harsh environments where neither symbiont can survive alone
What is one way where the relationship between cyanobacteria and fungi is not mutualistic and why?
cyanobacteria can exist without the fungus (doesn't need it) AND it is destroyed whenever the fungus obtain its nutrients (more parasitic)
What is Geobacter?
organism capable of using acetate to make CO2 and then can shuttle electrons to other organisms | lives in anaerobic environments
Where is acetate found?
anaerobic environments, it is the product of fermentation
What are the 2 organisms that Geobacter has a syntrophism relationship with (separately)?
Methanosarcina and Thiobacillus
What is Methanosarcina?
What is Thiobacillus?
a de-nitrifying organism