A Productive Week...........

On Monday of this week, we began desiccation and irradiation experiments. Colonies of each bacteria sample were placed in 300µl of liquid media they grew best in. From the 300µl, approximately 70µl was placed in 4 different tubes. One was kept as a control and the others were irradiated at different doses: one with 3 kGy, one with 6 kGy, and one with 16 kGy. 10µl of the control, 3 kGy, and 6 kGy were added to the media they grew best on previously with 5 samples per dish and keeping the different doses separate. Then 10 µl of each sample from the controls was added to wells on a desiccation tray and place is the desiccator for 42 days. On Wednesday, the 16kGy samples were ready, so we added 10µl of each sample to the media they grew best. Then we streaked starch plates with our cultures to test for the presence of amylases. After, we counted cultures on theGobi-1 non-irradiated samples. Then pictures were taken of the 1-4 dilutions of MA and the first dilutions of all 4 media (MA, 1/10 PCA, 1/100 PCA, PCA). Also 10 colonies were taken from the MA and 1/10 PCA dishes and streaked 2 per plate on new media: the colonies taken included colors pink, orange, yellow, and cream. Then CFU/g calculations were made. We found that the little red hill had the highest CFU/g over all. 1/10 PCA had the highest number for LRH and Gobi, while 1/100 PCA contained highest number for N97-1. We also found that for Gobi PCA was the lowest, for LRH 1/100 PCA was the lowest and MA was the lowest for N97-1.

Observations made with first dilutions of each sample, besides the 1/10 PCA and MA having the most growth and diversity, was that PCA had virtually only large cream colored cultures. Comparing PCA with the less concentrated PCA media, with almost no large cream colored cultures, it can be concluded that the large cultures require a lot of nutrients. Also comparing PCA with MA with no large cream cultures, it can be concluded that, either the large cream cultures have a low salt tolerance and the colored cultures require salt, or the colored cultures can grow with or without salt, just the larger cream cultures dominated the PCA media.

Gobi-1 Marine Agar:

Gobi-1 PCA:
Gobi-1 1/10 strength PCA:
Gobi-1 1/100 strength PCA: