Rationale:

Today we will be performing a spot titer to calculate the titer for an unknown lysate create last class.  

Procedure: 

1. Created an aseptic zone using an ethanol burner and cleaned the table with 70% ethanol and Cidecon.  
2. Lysate and eight small tubes were obtained for serial dilutions. 
3. Phage buffer was obtained as well.  
4. 10 uL of our 10^0 solution was added along with 90 uL of Phage Buffer to the first tube labeled 10^-1.  
5. The 10^-1 tube was mixed evenly, and 10 uL of this solution was added to the tube labeled 10 ^-2 along with 90 uL of phage buffer.  
6. The process continued until serial dilutions from 10^-1 to 10^-8 were created.  
7. Two plates were obtained and divided into 9 portions.  
8. 4 mL of LB Broth, 45 uL of CaCl2, 1 mL of Arthrobacter, and 5 mL of Top Agar were added into a 50 mL tube.  
9. 5 mL of solution was pipetted into each plate and let to set for 10 minutes.  
10. 5 uL of each serial dilution was added to each respective portion on the plates.  
11. 5 uL of Phage Buffer was added to the control portion of the plate.  
12. The two plates were left to sit for 15 more minutes and placed upright into incubator.  

Observations/ Results: 

Many small bubbles formed on our plates. Most of them were concentrated in the middle and the control portion of the plate.   

Next Step/ Conclusion: 

The results of the spot titer will be viewed and used to calculate the titer of the plate. Using the solution of the plates with a high titer, a webbed plate will be created to obtain more lysate.