Block B 3 Flashcards
environmental microbiology
what is isolation in pure culture important for
detailed studies in controlled (lab) environment
biotechnology applications
what are biofilms
assemblages of bacterial cells adhered to a surface and enclosed in an adhesive matrix excreted by the cells
what is the matrix typically composed of in biofilms
polysaccharides
what is the microbial hormone that controls biofilm formation
c-di-GMP
why do bacteria form biofilms
-self defense
-allows cells to remain in favourable niche
-allows bacterial cells to live in close associated with one another
what are the 2 ways of microbial isolation from the environment
direct isolation
enrichment culture
what is direct isolation used for
enumeration
detailed studies in controlled environments
what is enrichment culture used for
isolation (biotechnology)
risk assessment
what are the established medium and incubation conditions for
selective for desired organism
de selective for undesired organisms
3 ways that pure cultures can be obtained
streak plate
agar plate
liquid dilution
how can anaerobic bacteria grow method
agar shake up method
dilutions of mixed cultures in tubes of molten agar
how can aerobic bacteria grow method
plates
problems with direct counting
cannot distinguish between live and dead cells without special stains
small cells overlooked
phase contrast microscope req if stain not used
2 main ways to perform plate counts
spread plate method
pour plate method
to obtain the appropriate colony number the sample counted should always be …
diluted
what does MPN stand for
most probable numbers
how to obtain MPN
-serial dilution of inoculum in liquid until final tube shows no growth
-repeat until pure culture obtained
-estimation of microbial numbers for routine sampling
how to check for purity when finding MPN
-microscopy
-colony characteristics on plate
-test for growth in other media
-check for contamination
what must organisms balance
growth and death rates
what 2 methods are there for organisms to balance growth and death rates
oligotrophs
copiotrophs
what other names are there for oligotrophs
k strategists
autochthonous microbes
what other names are there for copiotrophs
r strategists
zymogenous microbes
what can be said about nutrient uptake with oligotrophs
nutrient uptake enzymes with low specificity but high affinity
what can be said about nutrient uptake with copiotrophs
nutrient uptake enzymes with high specificity but low affinity
what undergoes cell rounding and reduction in growth
arthrobacter (oligotroph)
what spores are metabolically active
streptomyces (copiotroph)
what does VBNC stand for
viable but nonculturable
metabolic activity of VBNC bacteria
very low
what is reduced in VBNC bacteria
nutrient transport
respiration
synthesis of macromolecules
what does VBNC have the ability to
become culturable once resuscitated
sources of novel targets
synthetic
non synthetic
natural products (fungi, plants, bacteria)
3 steps to see zone of inhibition
lawn of indicator organism
agar plug of producing organism
filter paper disk soaked in test compound
what does MIC stand for
minimum inhibitory concentration
