colony isolation

Know the difference between a mixed culture and a pure culture

• Mix culture: more than 1 bacterium (throat,skin,urine swab) 

• Pure culture: 1 bacterium strain

Know the different plating methods that we used to isolate pure colonies from a mixed culture 

• Lawn plate: aseptic tech→ hold lid facing down→ spread bacterium→ repeat rotate 4x 

• Streak plate: grid lines→ aseptic tech→ hold lid facing down→streak Q1 into Q2→ aseptic tech→ streak Q3 into Q4 (spreading smaller amount in individual colonies)

Why should you always leave the lid on the plate while inoculating? 

• Leave lid on always to avoid contaminating the surface such as fungal spores 

When inoculating a plate for the purposes of testing an unknown organism, you flame your loop,cool the loop, obtain your sample,remove the lid of your plate, and then what….? How do you (in what pattern) do you inoculate your plate? 

• Use a loop to make a line on the plate surface 

Pure cultures contain how many different types of organisms in them?

1

If you swab a patient’s (throat,skin,etc) is this pure culture or a mixed culture? 

• Mixed culture

What are the two different techniques or methods of inoculation used to obtain a pure culture from a mixed culture on a plate?

• Streak plate and lawn plate 

The term for individual masses of ONE single type of organism derived from one single cell that divided so many times that it became visible with the naked eye on a lab media is… 

Colony

How many individual regions or areas on a single agar plate do you create when performing the streak plate method of isolation?

4

Before you start of course you flame and cool your loop and then obtain your sample to make the plate. But then, when creating a streak plate between which two quadrants do you re-flame and cool your lop? 

1 and 2

The purpose of a streak plate or a spread plate method of isolation is to take a mixed culture and ultimately obtain what?

Pure culture