Topic 3: Microbial interaction

Question 1

mutualism

Answer 1

obligatory interaction between 2 species that benefit from the relationship

Question 2

Lichens

Answer 2

association between specific fungi and genus of algae
phycobiont: algae partner
Mycobiont: fungal partner

Question 3

protocooperation

Answer 3

non obligatory interaction between 2 species that benefit from the relationship

Question 4

cooperation

Answer 4

when cells involve in public goods sharing: secretion of a substance (comes at a cost) but benefits the larger population

Question 5

explain Marine Worm-Bacterial Protocooperative relationship

Answer 5

worm secretes mucous that feeds bacteria and bacteria supplements some degree of protection from environment to worm

Question 6

commensalism

Answer 6

interaction where one species benefits from but the other species has no effect

Question 7

syntrophy

Answer 7

symbiosis between 2 species that share metabolic processes between each other

Question 8

parasitism

Answer 8

relationship where one species benefits but it is detrimental to the other species

Question 9

amensalism

Answer 9

interaction where one species causes harm to another organism without any cost or benefits to itself

Question 10

what is antibiosis

Answer 10

substances secreted used to inhibit (harm) another species without harming or benefitting itself

Question 11

predation

Answer 11

interaction where one organism is killed and consumed

Question 12

explain predation cycle of microbes

Answer 12

1) attack phase
2) attachment
3) establish prey death
4) elongation and septation
5) prey lysis

Question 13

competition

Answer 13

when 2+ organisms are competing for a scarce resource
can be through chemical secretions or direct contact

Question 14

Quorum sensing

Answer 14

a form of communication between cells in response to cell density

Question 15

what is the overview or quorum sensing

Answer 15

autoinducer is released at threshold levels, attaches to receptor which initiates response for gene expression alteration

Question 16

what is AHL

Answer 16

autoinducer for intracellular communication between Gm- species

Question 17

what is AIP

Answer 17

autoinducer for intracellular communication between Gm+ species

Question 18

what is AI-2

Answer 18

autoinducer for intercellular communication between quorum sensing species

Question 19

explain QS in Gm- bacteria

Answer 19

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

Question 20

explain QS in Gm+ bacteria

Answer 20

AIP released at threshold levels, bind to histidine kinase (HK) activate it, then subsequently activate response regulator (RR) to direct transcription of target genes

Question 21

explain vibrio ficheri

Answer 21

Lux operon first found in vibrio ficheri–> produces luciferase which creates yellow politiscience

regulated by AHL and LuxR

Question 22

what are lux operons

Answer 22

cells involved in bioluminescence
LuxL: produces autoinducers
LuxR: produces bioluminescence

Question 23

Biofilms

Answer 23

aggregate of cells that trap to each other and surfaces

Question 24

who is Antoine Van Leeuwenhoek

Answer 24

discovered biofilms on tooth surfaces

Question 25

what are biofilms made of

Answer 25

extracellular polysaccharides, lipids, nucleic acids, and other biomolecules

EPS (extracellular polysaccharides) increase nutrient searching and moisture

Question 26

what are influences of biofilms

Answer 26

influence virulence, survival, and density of cells
can also chemically and physically alter surfaces they are on

Question 27

explain biofilm lifecycle

Answer 27

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

Question 28

what are advantages of biofilms

Answer 28

1) protect from extreme environments
2) seek nutrients and moisture
3) protect or amplify virulence
4) establish diversity

Question 29

quorum quenching–> how is it done

Answer 29

inhibition of QS done naturally through chemical secretions, naturally through eukaryotic hosts, or artificially (transgenic plants)

Question 30

microbiome

Answer 30

10-100 trillion microbial population within the human body, particularly human gut.

Question 31

benefits of microbiome

Answer 31

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

Question 32

what factors affect microbiome

Answer 32

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

Question 33

compare ancient VS modern microbiomes

Answer 33

ancient microbiomes more diverse than modern microbiomes
- due to increased contamination of environment/liquids or foods consumed. Increased consumption of alcohols/refined sugars/antibiotics

Question 34

what do microbiomes influence

Answer 34

the susceptibility with which one could contract disease such as
- cardiovascular
- diabetes
- cancer
- obesity
- Chrons disease

Question 35

what is Chron’s disease, how is it treated

Answer 35

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.

Question 36

what is narrow VS broad spectrum antibiotics

Answer 36

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

Question 37

how do bacteria resist antibiotics

Answer 37

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

Question 38

explain experiment of mice growing in germ free environment

Answer 38

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.