Microbiology Ch 27

symbiosis

stable association of one organism with another

methanotrophs and sulfate-reducing bacteria are linked by

metabolism

what does vibrio fischeri colonize?

bobtail squid light organ

what does penicillium secrete?

an antibiotic that inhibits bacterial growth

infection by a temperate bacteriophage will have what outcome?

neutral or beneficial

what will the outcome of a lytic infection always do?

harm the host

facultative interaction

microbe has alternative lifestyles

obligatory interaction

host cell is an absolute requirement for viral replication

many bacteria that live within eukaryotic cells are

obligate intracellular symbionts

metagenomics provides access to

uncultured microbes

microbiology relies on

cultures

humans are

holobionts

mutualism

some reciprocal benefit accrues to both partners

mutualism is an

obligatory relationship

cooperation

nonobligatory relationship (similar to mutualism)

antagonism

one organism negative impacts the other

mutualisms typically have their basis in

metabolism

in mutualism organisms typically

provide growth substrates or electron donors to others

syntrophy

occurs when one species benefits from the metabolic product of another

Syntrophy accounts for the majority of microbial interactions between free-living organisms in MOST

marine, freshwater, and soil habitats

methanogenic archaea are often found in syntrophic associations based on…

interspecies hydrogen transfer

interspecies hydrogen transfer

involves the removal of H2 from environment (enables fermentations that otherwise are thermodynamically unfavorable)

what ecosystems are termed anoxic methanogenic ecosystems?

sludge digesters, anaerobic freshwater sediments, flooded soils

what do anoxic methanogenic ecosystems host?

communities that generate H2, CO2, and acetate (fermentation end products)

why are mutualistic association common between microbes and insects?

insects consume plant sap or animal fluids lacking essential vitamins and amino acids

what is the model system for the study of mutualistic symbioses?

aphids and their y-proteobacterium Buchnera aphidicola

why is B. aphidicola a endosymbiont?

it lives within its host’s cells

what does a mature aphid contain?

bacteriocytes

what do B.aphidicola provide their hosts (in exchange for habitat and nutrients)?

amino acids absent in sap

B. aphidicola is an…

obligate symbiont

the inability of two organisms to grow without the other indicates…

coevolution

bacteriocyte

specialized eukaryotic cell that contains symbiotic bacteria

the main structural polysaccharides of wood are…

cellulose and hemicellulose

what do cellulose and hemicellulose combine with lignin to form?

lignocellulose

what do nitrogen fixing bacteria that live in the termite gut do?

solve problem of obtaining organic nitrogen

what problems do wood diets serve for the termite?

* degrading polysaccharides
* where to get organic nitrogen (needed for nucleotide and protein synthesis)

most termite-associated protists are members of

metamonada clade

what do the termite associated protists do in the termite gut?

ferment cellulose to acetate, CO2, and H2

what is termites preferred carbon source?

acetate

what is the responsibility of bacterial symbionts in termites?

convert CO2 and H2 to acetate (vis Wood-Ljungdahl pathway)

termites harbor methanogens that thrive based on…

interspecies hydrogen transfer

why is motility essential?

prevent protist expulsion by the termite gut and to acquire food

purpose of primary producers in an ecosystem?

organisms that capture energy from nonliving source

all primary producers are…

autotrophs

how do autotrophs fuel reactions?

phototrophy or lithography 

what do some autotrophs use as an energy source?

CO2

photrophy

photosynthetic processes

lithotrophy

uses reduced, inorganic chemicals as electron source

what do termites make their own of?

cellulolytic enzyme

ONLY mutualistic protists can…

complete lignocellulose degradation

what does *Trichonympha* sp. rely on Elusimicrobium to do?

convert glutamine to amino acids and nitrogenous compounds

Elusimicrobium is a….

bacterial endosymbiont

what do marine invertebrates harbor?

endosymbiotic dinoflagellates

how do hermatypic corals get energy?

using photosynthetic symbiodinium

what do protists that line gastrodermis do?

give 95% of fixed-carbon (in exchange for nitrogenous compounds)

how does coral bleaching occur?

loss of either the photosynthetic pigments from dinoflagellates or complete expulsion of dinoflagellates from coral

what causes coral bleaching?

temperature increase

what happens during and following the bleaching of coral?

microbial community is in disequlibrium, stressed coral susceptible to pathogens

what diseases can kill caribbean coral?

white plague and yellow blotch disease

tube worms (Riftia) at vents are….

mutualistic with bacterial endosymbionts

what do tube worms rely on since they have no digestive tract?

bacteria to provide organic carbon

where do hydrothermal vents occur?

thousands of meters below ocean surface

ruminants

animals that have stomach divided into four compartments and chew a cud

rumen

upper part of ruminant stomach

that does the rumen contain?

large, diverse population of microbes

what kind of relationship does the ruminant and microbial community have?

mutualistic

what to microbes in rumen do?

carry out anaerobic metabolism

what to the community of microbes in rumen do?

act to make enzymes needed for hydrolysis of simple carbs

how does cooperation differ from mutualism?

relationship is not obligatory

example of cooperation

bacteria contributes to reproductive success

fungal highway

physical network of fungal hyphae that promote bacterial dispersal

how to hyphae spread?

on solid surfaces growing towards nutrients

why do bacteria move along hyphal surface?

to explore new enviornments

bacterial motility is restricted to…

liquid phase

surface tension maintains…

a water layer around hyphae

lichens

association between fungi and green algae

mycobiont

fungal partner

photobiont

alga or cyanobacteria partner

mycobionts provide

water, minerals, and firm substratum for growth

photobiont provides…

oxygen

predation

killing (benefit after the victim is killed)

parasitism

exploitation (benefit while victim is alive)

competition

uneasy truce between microbes

restriction-modification

chemically distinguish oral and host DNA and hydrolyze viral DNA

CISPR/Cas system

Recognize viral DNA by comparing samples from previous encounters to identify and degrade viral genomes

grazing

process by which protozoans consume bacteria

what is grazing a primary mechanism for?

transfer of carbon and energy from bacteria to more complex organisms

bacteria defensive mechanisms to avoid consumption

* grow larger
* form biofilms

epibootic predators

attach to prey’s surface and lyse to release prey’s cytoplasmic contents

endobiotic predators

invade victim’s cytoplasm where they consume contents to get energy

Myxococcus is a….

facultative predator that consumes organic matter released from dead organisms

Myxococcus displays predation by using…

gliding motility to creep toward prey while releasing degradative enzymes

parasite and host…

coexist

parasitism can involve…

nutrient acquisition, physical maintenance, or both

in parasitism if equilibrium is shifted…

one organism may die

genomic reduction is common in…

one organism may die

what are the two possible outcomes of competition

* contact-independent growth inhibition
* contact-dependent growth inhibition

genomic reduction occurs when…

symbiont has become dependent on host for specific functions

genomic reduction

discard unused genetic information

competition

arises when different organisms try to acquire the same resource