Microbiology Lecture - Exam 4

how many diseases can be caused by a microbe?

1

what causes cholera?

Vibrio cholera

what causes the flu?

influenza

how many microbial causes can a disease have?

many!

true or false: we know what bacteria causes conjunctivitis (pink eye)

false - conjunctivitis is caused by many different bacteria and we cannot isolate one cause

true or false: we know what bacteria causes meningitis

false - meningitis is caused by many different bacteria and we cannot isolate one cause

what is symbiosis

an association of two or more different species of organisms where at least one member benefits

what is the term for an association of two or more different species of organism where at least one organism beneftis

symbiosis

what is the term for a microbe that interacts with a larger organism

symbiont

what is a symbiont

a microbe in symbiosis with a larger organism

in symbiosis, what is the larger organism called

host

what is a host

the larger organism in symbiosis

what is an ectosymbiont

organism located on the surface of another orgamism

what is the term for an organism located on the surface of another organism

ectosymbiont

what is an endosymbiont

organism located within another organism

what is the term for an organism located within another organism

endosymbiont

what is a consortium

hosts that have more than one associated symbiont

what is the term for a host that has more than one associated symbiont

consortium

what is mutualism?

a microbial interaction where both partners benefit and there is some degree of obligation

what is a microbial interaction where both partners benefit and there is some degree of obligation?

mutualism

what is the relationship of aphids and Buchnera aphidicola?

mutualism, aphids consume plant sap which doesn’t have amino acids and vitamins, the endosymbiotic microbe lives inside the insect and provides them with those vitamins/amino acids (arginine). Aphid provides secure habitat and nutrients

the inability of aphids/B. aphidicola to grow without the other is an example of ________

coevolution

how can B. aphidicola have such a small genome?

only has the bare minimum, all other functions are reliant on the aphid host

what is the relationship between termites and protozoan symbiont?

termites eat wood which has cellulose (long chains of glucose) which they can’t break up, the protozoan digests glucose and gives termite nutrients, termite provides food for protozoan

what is the other part of the protozoan-termite relationship?

the protozoan symbiont relies on it’s own bacterial symbionts

what bacteria resides in a termite’s protozoan?

TG1 and spirochetes

what does TG1 do in the termite’s protozoan?

makes glutamine from NH3

what do spirochetes do in the termite’s protozoan?

provide motility for the protozoan

what is a ruminant

animals that have a stomach that is divided into four compartments

what is the term for an animal that has a stomach divided into four compartments?

ruminant

how do ruminants aquire nutrients?

by fermenting plants in a special compartment (called the rumen) before digesting them

what is a rumen?

pouch filled with partially digested gas (useable pulp), upper part of a ruminant’s stomach

what is inside of a ruminant’s rumen?

large, diverse populations of microbes (bacteria, archaea, fungi, protists), up to 10² organisms per mL

(also cud/grass pulp)

how does the rumen ecosystem work?

plants/grass are ingested, coated with saliva, and swallowed → in rumen, grass is coated with microbes and partially digested into pulp → the pulp is regurgitated, chewed, and re-swallowed → liquified grass passes into omasum/abomasum to be further digested

what is the relationship between ruminants and their microbial community?

mutualistic - microbial community within ruminant also have a mutualistic relationship

what is cooperation?

realtionship that benefits both organisms involved, but is NOT obligatory

what is a relationship where both organisms benefit, but is not obligatory

cooperation

cooperation typically involves ___________ relationships

syntrophic

what is a syntrophic relationship?

a relationship where one species lives off the products of another species

syntrophic relationships often involved linked ________ and _______ cycles

carbon, nitrogen/sulfer

why are cooperation relationships not obligatory?

the organism COULD produce the product itself, but if someone is putting it out for free they don’t have to use the production energy

what is commensalism?

a relationship where one organism benefits, but the other is unaffectedw

what is the term for a relationship where one organism benefits and the other is unaffected?

commensalism

in a commensalism relationship, the organism that benefits is called a ______

commensal

what is a commensal?

the organism that benefits in a commensalism relationship

commensalism relationships are often ________

synotrophic

nitrification is an example of what kind of interaction?

commensalism

what bacteria are involved in nitrification

Nitrosomonas (NH₃→NO₂) and Nitrobacter (NO₂→NO₃)

microbial succession during the spoilage of milk is an example of what kind of relationship?

commensalism

how. is microbial succesion in the spoilage of milk an example of commensalism?

fermenting bacteria promote the growth of acid tolerant species

what is the BEST example of commensalism?

formation of biofilms

why is the formation of biofilms an example of commensalism

initial colonizer helps other microorganisms attach

what is predation

one organsim gains and the other is harmed

in a predation relatinoship, the organism that is harmed is called the _____ and the organism that gains is called the _____

prey, predator

what is the relationship called when one organism gains and the other is harmed?

predation

where can the predator attack the host cell from?

inside or outside of the prey cell

Bdellovibrio is an example of what relationship?

predation

why is Bdellovibrio an example of predation?

penetrates the cell wall, grows outside the plasma membrane in periplasm

Vampirococcus is an example of what kind of relationship?

predation

how is Vampirococcus an example of predation?

uses an epibiotic mode of attacking prey, lives on the surface (outside of cell)

what kind of relationship is Daptobacter?

predation

how is Daptobacter an example of predation?

penetrates prey then directly consumes the cytoplasmic contents

Myxococcus is an example of what relationship?

predation

how is Myxococcus xanthus an example of predation?

cells use gliding motility to creep, overtake their prey, and release degrading enzymes

what is parasitism?

one organism gains (parasite) and the other is harmed (host)

what is the term for a relationship in which one organism gains and the other is harmed but NOT killed

parasitism

what is the organism called that gains in a parasitism relationship?

parasite

what is the organism called that is harmed in a parasitism relationship

host

in a parasitism relationship, what usually happens to the host?

the host is usually harmed, but NOT killed.

there is always some degree of _____________ between a host and a successful parasite

co-existance

what are the hallmarks of a parasitic relationship

• not beneficial for host

• host grows better without parasite

what is ammensalism

association between two organisms where one organisms is inhibited (harmed) and the other is unaffected

what is the term for a relationship where one organism is harmed and the other is unaffected

ammensalism

antibiosis is one specific type of ________

ammensalism

what is antibiosis

release of a specific compound like antibiotic production by fungi

South American Attine ants are an example of what kind of relationship?

ammensalism

how are South American Attine ants an example of ammensalism?

ants cultivate a garden of fungi as food, another parasitic fungus species preys on ant’s garden, ants use antibiotic producing actinobacteria to control the fungal parasites

what is competition?

when two organisms try to aquire or use the same resource

what is the term for two organisms trying to aquire or use the same resource?

competition

what are the two possible outcomes of competition?

1. one organism dominates - stronger organism reproduces more and outcompetes weaker organism

2. two organisms share the resource - both organisms survive but at lower population levels

what is the difference between microbiome and microbiota?

microbiome is all the genes carried by the mcirobes, microbiota are the actual organisms

what was the originally said ratio of bacteria to human cells? what was it revised to?

10:1, 1:1

what is a metagenome

all of the genes of the host AND the microbiota

what is a superorganism

the result of gene-encoded metabolic processes of the host integrating with those of the symbiont

creates a blend of host and microbial traits where host and microbial cells co-metabolize various substances, resulting in unique processes

what technology has revolutionized study of normal human microbiota?

16S rRNA sequencing

human body’s normal microbiota or microflora vary depending on what factors?

• anatomical site

• age

• sex

• diet

an unborn baby is ________, and they are ________ during the birthing process

sterile, inoculated

what happens to a baby’s microbiota as the baby grows?

microbiota changes, eventually settles down to a reasonably stable consortium

what is a consortium?

the “settled down” and stable microbiota in a growing baby

what does antibiotic treatment do to the human consortium/microbiota?

can disrupt the balance, but usually returns to normal after antibiotics are removed

what is the usual relationship between the normal microbiota and their human host?

usually mutually beneficial

what do the normal microbiota in the human host do? what do they get in return?

bacteria produce vitamins B and K in the gut, which are beneficial. In return, they get a safe habitat with plenty of nutrients.

Also help to prevent the colonization of pathogens

normal microbiota that can become pathogenic under the right circumstances are called ___________

opportunistic pathogens

what circumstances can opportunistic pathogens take advantage of?

compromised host or host with lowered resistance to infection

what is a pathogen?

any disease-producing microorganism

what is pathogenicity?

ability to produce pathological change or disease

a host that has more than one associated symbiont is a _________

consortium

ability of organisms in a mutualistic relationship to grow without the other is an example of __________

coevolution

is a cooperation relationship necessary for the survival of both organisms?

no, but mutualism is

_______ lies between commensalism and predation, where one organism is harmed but not killed while the other gains

parasitism