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
