to determine the
CFU
(colony forming units)

per ml of sample

     The T-streak method is a reliable aseptic technique that can help to 
         isolate colonies from a mixed population of bacteria. The method
          divides a Petri dish into three sections and streaks each section.

1. divide your plate into three sections by drawing a T on your plate 
2. flame sterilize an inoculation loop
3. dip the loop into your sample of bacteria
4. streak the first section in a zigzag pattern
5. sterilize the loop again
6. rotate the plate 90 degrees
7. streak the second section, starting in the previously streaked section
8. sterilize the loop
9. rotate the plate 90 degrees
10. streak the third section, starting in the previously streaked section

aseptic technique
and
the T streak

what is media vs a culture?

what and why?

          When use CFUs?
 experiments, food samples, 
 probiotic supplements

 bacteria in a solid medium is   expressed as CFU/g

 bacteria in a liquid sample is   expressed as CFU/mL

isolating colonies:

the T streak

                   Colony-forming units (CFUs)
  measure the number of bacterial cells in a sample
                           To calculate CFUs:
1. Dilute the sample in a series of 1:10 dilutions
2. T streak plate a specific volume of each dilution 
3. Incubate 
4. Count the number of colonies on the plates
5. Calculate the total CFU/mL 

how?