Micro lab final

What is the purpose of the streak plate technique?

Isolate individual bacterial cells from a mixed or dense sample so they can grow into separate, pure colonies.

What is contamination

accidental introduction of unwanted microorganisms into a culture, sample, or sterile environment.

How could you tell if your streak plate has a contaminant

has more than one colony type, indicating that unwanted microorganisms are present.

selective media

Contain inhibitors that allow only certain bacteria to grow.

Msa can grow

staphylococcus species, salt tolerant

msa inhibits

Most other bacteria that cannot tolerate high salt

Obligate aerobe

Grows only at the top

what happens to obligate anaerobes in the presence of oxygen

killed or inhibited by oxygen and can only grow in environments without oxygen.

How are anaerobic bacteria cultured in the lab

oxygen-free conditions, using anaerobic jars, anaerobic chambers, or reducing media to prevent oxygen exposure.

What was the purpose of antiseptic lab

evaluate the effectiveness of different antiseptics in killing or inhibiting bacterial growth.

Why did we inoculate a “0” sector on the plate?

serve as the control

Why did we time the different streaks in the experiment

o measure how quickly each disinfectant or antiseptic killed or inhibited the bacteria.

Resistant

drug doesnt work

susceptible

drug does work

Obligate anaerobe

Grows only at the bottom

Facultative anaerobe

Grows throughout the tube, but most growth at the top

Microaerophile

Grows in a thin band just below the top

Aerotolerant anaerobe

Grows evenly throughout the tube

differential media

Contain indicators that cause different bacteria to appear differently based on their biochemical reactions.

emb allows growth of

Gram negative bacteria

emb inhibits

gram positive bacteria

blood agar inhibits

generally does not inhibit bacteria

emb allows growth of

Most bacteria