Topic 3: Microbial interaction Flashcards
mutualism
obligatory interaction between 2 species that benefit from the relationship
Lichens
association between specific fungi and genus of algae
phycobiont: algae partner
Mycobiont: fungal partner
protocooperation
non obligatory interaction between 2 species that benefit from the relationship
cooperation
when cells involve in public goods sharing: secretion of a substance (comes at a cost) but benefits the larger population
explain Marine Worm-Bacterial Protocooperative relationship
worm secretes mucous that feeds bacteria and bacteria supplements some degree of protection from environment to worm
commensalism
interaction where one species benefits from but the other species has no effect
syntrophy
symbiosis between 2 species that share metabolic processes between each other
parasitism
relationship where one species benefits but it is detrimental to the other species
amensalism
interaction where one species causes harm to another organism without any cost or benefits to itself
what is antibiosis
substances secreted used to inhibit (harm) another species without harming or benefitting itself
predation
interaction where one organism is killed and consumed
explain predation cycle of microbes
1) attack phase
2) attachment
3) establish prey death
4) elongation and septation
5) prey lysis
competition
when 2+ organisms are competing for a scarce resource
can be through chemical secretions or direct contact
Quorum sensing
a form of communication between cells in response to cell density
what is the overview or quorum sensing
autoinducer is released at threshold levels, attaches to receptor which initiates response for gene expression alteration
what is AHL
autoinducer for intracellular communication between Gm- species
what is AIP
autoinducer for intracellular communication between Gm+ species
what is AI-2
autoinducer for intercellular communication between quorum sensing species
explain QS in Gm- bacteria
LuxL (converts SAM-AHL) produces AHL, at threshold AHL binds to LuxR and activates luxR for bioluminescence OR another specific receptor to alter gene expression
at low population density, AHL is low and unstable and is degraded
explain QS in Gm+ bacteria
AIP released at threshold levels, bind to histidine kinase (HK) activate it, then subsequently activate response regulator (RR) to direct transcription of target genes
explain vibrio ficheri
Lux operon first found in vibrio ficheri–> produces luciferase which creates yellow politiscience
regulated by AHL and LuxR
what are lux operons
cells involved in bioluminescence
LuxL: produces autoinducers
LuxR: produces bioluminescence
Biofilms
aggregate of cells that trap to each other and surfaces
who is Antoine Van Leeuwenhoek
discovered biofilms on tooth surfaces
what are biofilms made of
extracellular polysaccharides, lipids, nucleic acids, and other biomolecules
EPS (extracellular polysaccharides) increase nutrient searching and moisture
what are influences of biofilms
influence virulence, survival, and density of cells
can also chemically and physically alter surfaces they are on
explain biofilm lifecycle
1) initial attachment on surface mediated by Vander Waals
2) irreversible attachment via pilus attachment to each other and surfaces
3) maturation I: cells learn QS and undergo growth and multiplication
4) maturation II: cells establish growth and may develop antibiotic resistance
5) dispersion: cells may leave biofilm
what are advantages of biofilms
1) protect from extreme environments
2) seek nutrients and moisture
3) protect or amplify virulence
4) establish diversity
quorum quenching–> how is it done
inhibition of QS done naturally through chemical secretions, naturally through eukaryotic hosts, or artificially (transgenic plants)
microbiome
10-100 trillion microbial population within the human body, particularly human gut.
benefits of microbiome
1) synthesize and secrete vitamins
2) protect against pathogen colonization
3) cross-reactive antibodies: antibodies that recognize pathogens with similarity
4) promote development of some tissues
what factors affect microbiome
1) diet
2) misuse of medication
3) environment
4) family genes
+ delivery: whether one is vaginally or C-section delivered
+ feeding: whether one was bottle fed or breast fed
compare ancient VS modern microbiomes
ancient microbiomes more diverse than modern microbiomes
- due to increased contamination of environment/liquids or foods consumed. Increased consumption of alcohols/refined sugars/antibiotics
what do microbiomes influence
the susceptibility with which one could contract disease such as
- cardiovascular
- diabetes
- cancer
- obesity
- Chrons disease
what is Chron’s disease, how is it treated
Clostridium difficile bacteria found in feces can cause diseased if contracted through contamination (if feces contacts eyes/mouth etc.)
treated by fecal microbiota transplantation where ones healthy stool (healthy microbiome) is transferred to colon of another with unhealthy microbiome.
what is narrow VS broad spectrum antibiotics
narrow: works against a limited group of bacteria
Broad: works against a broad group of bacteria
there tends to be high misuse of broad spectrum antibiotics
how do bacteria resist antibiotics
1) stopping bacteria from reaching target high conc.
- modifying antibiotic
- pumping out antibiotic
- destroying antibiotic
2) modify target receptor for antibiotic
- decrease permeability to antibiotics
explain experiment of mice growing in germ free environment
mice grown in germ free environment were susceptible to getting ill from as much as 10 salmonella cells
mice conventionally grown were able to withstand around millions of salmonella cells without sickness.
