Revised UV Exposure on Deinococcus xinjiangensis

 Introduction 

Previously,  D.xinjiangensis was grown in 1 TGY and 2 R2B broths and exposed to UV radiation in 10 intervals from 100,000-999,999μJ/cm² . Growth was shown in majority of energy levels for cells grown in TGY broth whereas no growth was shown for either of the cells grown in R2B. Some adjustments to find a threshold for the R2B cells include: narrowing the domain of energy in X100μJ/cm² ,  exposing in the same media , and shortening the duration of exposure. We're going to do a short experiment on 2 broths grown in R2B only to better understand a threshold for these cells.


Methods


To prepare, two R2B samples were grown overnight and normalized to an OD value of 1. Next 50μL were pipetted from these cells and exposed on parafilm to 50,000μJ/cm² for 2 minutes.  This step was repeated for the energy level of 100,000μJ/cm². Next, 20μL of irradiated cells were transferred into a tube containing 480μL of R2B , to make a total volume of 500μL. These 2 pairs were then inoculated two seperate R2A plates and incubated for 4 days at 30 degrees Celsius. Lastly, non-irradiated cells were also inoculated on R2A plates and followed the same incubation treatment. 


Results


Irradiated and non-irradiated cells post-incubation


Discussion

No growth of D.xinjiangensis was found post-UV exposure. However, contamination can be seen on the 50,000μJ/cm² R2B plate. Non-irradiated cells also showed growth, but contained a different dilution factor than the cells that were treated. In the future, it would be best to increase number of datapoints, and the domain of energy exposure should be 10 intervals between 100-50,000μJ/cm² . Additionally, all samples need to be diluted with the same dilution factor pre-inoculation. Lastly, the dilution factor needs to stay 1:10, so media needs to be decreased from 480μL to 180μL.







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