quiz 7 Flashcards
What is the morphology of enterobacteria?
facultativ anaerobes, gram negative rods, oxidase negative, motile
What are the key distinguishing factor of coliforms?
Ferment glucose to produce acid and gas
How do we select for enterobacteria?
in tube: fill with broth so that the lower regions turn anaerobic
on plate: incubate aerobically to kill off other anaerobic gut bacteria
What is special about EMB agar?
selective and differential, dyes inhibit growth of gram + and g- cocci, has lactose indicator
what is the indole test?
measures ability for organism to break down amino acid tryptophan using tryptophanase2
What is the physical appearance of E.coli on EMB agar?
irregular, flat, almost black colonies with green sheen
Why use the lactose mineral salt?
To restrict streptococcus and micrococcus
What is quorum regulation?
population density dependent gene regulation
What is casein? Where is it present?
Casein is a substrate that is hydrolyzed by caseinase, its present in milk
What encodes for caseinase in psedumonads?
AHL reception
How will we know if caseinase is quorum regulated?
If we have growth in the higher population density only
What is a positive caseinase test?
Clear colonies
How will we know if there’s no caseinase present?
Pseuds will grow in casamino acids but not in casein
What do luminsecent bacteria require to reproduce?
organic substrate, e- acceptor and donor, luciferase
Where are luminescent bacteria present?
In photo bacterium and vibrio
What is the gram morphology and classification of luminescent bacteria?
gram negative facultative anaerobes with flagella
What is a saprophyte?
A bacteria that can live on organic bacteria
What is luciferase?
a very energy costly enzyme that catalyzes the light rxn to produce luminescence
How do conidia appear under gram stain?
gram positive spheres or ovals
What are sporophores?
conidia bearing hyphae of a colony
Which antibiotic will actinomycetes produce?
sterptomyces
How do we know if our actinomycete produces antibiotics?
It will diffuse into the media
What is the purpose of SWC media with agar degraders?
it is a rich media that will be used to see if our bacteria has exoenzyme production?
What is the purpose of ASN+glu with agar degraders?
catabolite repression, how affects agarase expression
