MCB Final Exam CH 27, 33, 32, 34, 35
What size are the stable genomes that B. aphidicola have?
0.65Mb
What are the possible outcomes of competition?
1) one organism dominates while one is excluded (ex. chemostat) 2) two organisms share the resource at lower population levels
B. aphidicola makes how many essential amino acids for aphids?
10
How large is the microbial community inside the rumen?
10^12
The human microbiome project has managed to collect ____ sequence data from over _______ human samples
16S; 5,000
By what age should we have acquire an adult-like microbiome?
3 years old
Ruminants, like cattle and deer, have stomachs divided into how many compartments?
4
The next-generation beneficial microbes are called __________ . Together with its host, they form a relationship based on cooperation.
Akkermansia muciniphila
____________ is a type of mycobiont that includes yeast and molds
Ascomycota
Chemolithotrophic endosymbionts use the __________-_____________ cycle to fix carbon dioxide into organic CO2 which can be used by their host (the Riftia tube worm) in sulfide-based mutualism.
Calvin-Benson
What bacteria encourage the growth of bifidobacteria in the human gut, by reducing the enviornment?
E.coli & streptococci
What protozoan parasite is sporadically found in AIDS patients?
Encephalitozoon cuniculi
True or False: Babies with bifidobacteria in their gut have robust responses to vaccines
True
True or false: Parasites can only obtain biochemical precursors and energy while its host is alive.
True
True or False: Commensalism is often syntrophic.
True.
What is the worlds most infectious microbe?
Wolbachia pipientis
Aggregations of many types of organisms in stable relationships are now referred to as
a metaorganism or holobiont
In microorganism-insect mutualism, what does the insect host provide?
a secure habitat and nutrients
What emerges when host and microbial traits blend together and they begin to co-metabolize substrates to form unique products?
a superorganism
The "true stomach" of a ruminant is called the __________.
abomasum
In syntrophic relationships, organic substrates are oxidized so that H2 can be produced, and then quickly consumed by methanogens. In cows, a ruminant, what is consumed by methanogenic archaea to generate methane?
acetate, CO2, and H2
Protists are critical for a termite's ability to consume a diet of only wood. The protists ferment cellulose to _____.
acetate, hydrogen, and carbon dioxide
What are the five phyla present in most human microbiomes?
actinobacteria bacteroidetes firmicutes fuscobacteria proteobacteria
Attine ants use antibiotic-producing streptomycin (Pseudonocardia) to control fungal parasites (Escovopsis) which hinder the growth of their fungal garden. This relationship between Pseudonocardia and Escovopsis is an example of
amensalism
In ________________, a unidirectional relationship, one partner benefits while the other partner suffers negative effects.
amensalism
The production of antibiotics to inhibit or kill other susceptible microorganisms is a classic example of
amensalism
What does bifidobacteria, which is found in breastfed babies, synthesize from carbs?
amino acids and growth factors
What makes amensalism a unidirectional process?
an organism is adversely effected by the secretions of another organism.
The model system for microorganism-insect mutualism is between the insect __________ & the microbe____________
aphids; B. aphidicola
Production of __________ by bacteria, ______________ by insects/animals, and ______________ during fermentation are all examples of amensalism.
bacteriocin; antibacterial peptides; organic acids
what is protrophic (makes amino acids and growth factors) and can be used a probiotics in breastfeeding infants?
bifidobacteria
The obligate nature of the relationship between aphids and B. aphidicola demonstrate that the two species have _______________, so much so that they share amino acid biosynthesis pathways.
coevolved
All symbionts must do what within the host?
colonize, reproduce, persist, and then transmit to a new host
What is the symbiont that benefits from commensalism called?
commensal
In ___________ , a unidirectional relationship, one partner benefits and the other is neither helped nor harmed
commensalism
nitrification (NH3->NO2->NO3) is an example of
commensalism
In _____________, different organisms within a population try to acquire the same resource. The resource can be a physical location or a limiting nutrient
competition
What accounts for the phenomenon of colonization resistance or the capacity of gut flora to prevent pathogen growth?
competitive exclusion principle
What type of host has more than one expected symbiont?
consortium
In ________________, both partners benefit and can also live independently, although it might not function as well
cooperation
X. nematophila (bacteria) contributes directly to the reproductive success of its host, S. carpocapsae (worm). When the host has infected an insect, the bacteria are released into the insect through excrement where they begin to send out signals that trigger the host to develop into adulthood. This model system is an example of what positive symbiotic relationship?
cooperation
Cud, a small ball of partially digested grasses that Ruminants chew, is an example of what type of evolved strategy?
eat now, digest later
What type of symbiont is usually located on the surface of a larger organism?
ectosymbiont
Which two of the following benefits are provided to ruminant animals by methanogenic archaea?
efficient removal of hydrogen and essential vitamin synthesis
Trichonympha is a protists (& endosymbiont) that has its own endosymbiont bacteria called _________________ which converts glutamine into amino acids.
elusimicrobium
"______________" predator is used to describe individual cells, like Daptobacter and Bdellovibrio cells, that invade their preys cyto/periplasm and consume its contents to obtain energy and precursors for cell division
endobiotic
What type of symbiont is located inside another organism?
endosymbiont
"____________" predator is used to describe individual cells, like vampirococcus cells, that attatch to their preys surface.
epibiotic
What are the three classes of microbial predators?
epibiotic, endobiotic, and facultative predators
According to Gause's competitive ______________ principle, if one of two competing organisms can dominate an environment, it will overtake the other organism.
exclusion
"____________" predator is used to describe populations of cells, like Myxococcus "wolf pack" cells, that use gliding motility to cover their prey so they can release degradative enzymes
facultative
How can a host acquire a symbiont?
from the environment horizontally from host to host vertically through reproduction
What can be coupled with genomic studies for maximum benefit?
gnotobiotic "germ-free" animals
What does it mean to have an obligatory relationship?
host & symbiont are dependent on each other and can't live separately
In 2007, the NIH conducted the human microbiome project in an attempt to define normal population of microbiomes in and on human beings. This information can shed light on
how microbes and humans interact in healthy and disease states
Where do aphids contain B. aphidicola?
in bacteriocytes
nitrogen fixing bacteria are found where in a termite?
in its gut
What are the beneficial effects of predation?
increased rates of nutrient cycling which makes the microbial loop function more efficiently
The relationship between a consortium (host) and their symbionts can be ____________, ____________, or ____________
intermittent, cyclic, permanent
In various anoxic methanogenic ecosystems, fermentative bacteria, like Syntrophobacter, produce excess H2, which is consumed by methanogenic archaea to produce methane. This type of syntrophy is known as ______________________.
interspecies hydrogen transfer
What does 1)cow's gut, 2) biofilm formation, & 3) acid waste production (milk spoilage), demonstrate in commensalism associations?
it demonstrates how an organism will modify the environment to make it more suitable for another organism to function.
How does bifidobacteria limit the growth of certain pathogens in infants?
its surface proteins bind to sugars allowing it to ferment and lowering the pH of the babies gut.
Controlled parasitism that can only occur when organisms are deprived of nutrition. An example of this is
lichens
Methanogenic archaea in termites use acetate, CO2, and H2 to make
methane
gnotobiotic animals, or "germfree animals," are raised in sterile environments and used to study the effects of ______________________. They also tend to lack a robust immune response
microbes on animal health
What helps select for non-pathogenic bacteria in a humans gut?
milk
What is essential to prevent the protist from leaving the termite gut?
motility, which is aided by spirochetes on the protist surface
In ______________, both partners benefit and the relationship is obligatory
mutualism
The protozoan-termite relationship is an example of ___________ and endosymbionts.
mutualism
What type of symbiosis is beneficial for both partners?
mutualism cooperation commensalism
What word is being used to replace the term "commensals" when describing a humans microbiome?
mutualist
Normal microbiota prevents pathogens from colonizing its host and produces vitamins (B12 & K) that are beneficial to its host. This relationship is said to be
mutually beneficial
___________, a fungal partner/parasite, provides water, minerals, and substratum needed for growth to the lichen
mycobiont
What are examples of parasites that have undergone genomic reduction, to the extent that they can no longer survive outside host cells?
mycoplasma genitalia (human), B. aphidicola (aphids), m. leprae (human), and E. cuniculi (protist parasite)
What bacteria carries out the second step of nitrification (NO2->NO3)?
nitrobacter
What bacteria carries out the first step of nitrification (NH3->NO2)?
nitrosomonas
The ______________ is the lower portion or "antechamber" of a ruminants stomach
omasum
_____________________ are typical members of the microbiome that will only produce disease when the host is compromised
opportunistic pathogens
Within the rumen, bacteria breaks down d-glucose by cleaving its B(1->4) linkages. The d-glucose is then fermented into which four of the following products?
organic acids, fatty acids, methane, carbon dioxide
In _____________, the microbe and host coexist temporarily until the relationship equilibrium is upset. If equilibrium shifts to the microbe, the host is harmed (and vice versa).
parasitism
A pathogens ability to cause disease is called its
pathogenicity
___________, or alga/cyanobacteria, provides organic carbon and oxygen to the lichen
phycobiont
In ________________, the dominant species will attack and kill its prey. Only then may the dominant species obtain its preys biochemical precursors and energy.
predation
What type of symbiosis has a negative impact on one or both partners?
predation (killing) parasitism (exploitation) amensalism competition
Over time, individual organisms in symbiotic relationships will often lose nonessential genetic information in a process called genomic _____.
reduction
In the termite gut, protists ferment cellulose to acetate, CO2, and H2. The acetate is the termite's preferred carbon source, and the CO2 and H2 are used by bacterial symbionts to produce more acetate by the _____.
reductive acetyl CoA pathway
The __________ is a smaller, honeycomb-like region of the upper part of a ruminants stomach.
reticulum
The ____________ is the upper part of a ruminants stomach that expands to form a large pouch and is an anaerobic fermentation chamber where various microbes digest grasses eaten by the animal.
rumen
In a syntrophic relationship, the growth of one organism depends on (or is improved by) which types of factors produced by nearby organisms?
substrates, growth factors, and nutrients
____________ is an association between two or more different species of organisms
symbiosis
An association in which the growth of one organism depends upon, or is improved by, factors provided by a nearby organism is called _____.
syntropy
Why do termites need nitrogen-fixing bacteria?
the bacteria obtain organic nitrogen which the termite needs to synthesize nucleotides and proteins
How is biofilm formation an example of commensalism?
the bacteria that initially colonizes the exposed surface modifies it, which makes it easier for other organisms to attach to the surface
How is acid production during milk spoilage an example of commensalism?
the fermenting bacteria signal acid tolerant species of bacteria to start growing
What hosts all the genes of the host and microbiota?
the microbiome
How does the relationship between protozoans and termites work?
the protist (Trichonympha) breaks down lignocellulose in wood and fixes nitrogen into a usable form so that the termite can obtain nutrients
Why can commensal organisms survive without their host?
they are not directly dependent on the host's metabolism
What epibiotic predator cell attaches to its preys outer membrane and secretes enzymes to lyse and signal the release of its preys cytoplasmic contents?
vampirococcus cells
In microorganism-insect mutualism, what does the microbe provide?
vitamins and amino acids
Many marine invertebrates have endosymbionts in their tissues called _______________, like Symbiodinium, which fix carbon to satisfy energy requirements in their host.
zooxanthellae
