Don’t used borrowed media.............

This was a busy week on Monday we counted our irradiated soil plates. We then took theses counts and used them to determine the percent survival of organisms compared to the un-irradiated plates that we counted earlier. For our organisms the higher percent survival and diversity was on the lower nutrient plates this is most likely due to the resemblance of the availability of nutrients on these plates to the natural environments of the organisms. Our Isolates did not like salt after being irradiated nothing grew on them at all. We used the irradiated soil plus media enrichment broths to streak plates to see what grows along with picking 10 colonies from the irradiated plates that most resembled our current isolates to do further test too. There is a graph in a paper given to us by Dr. Rainey that has a graph of the survival percentages after different doses or ionizing radiation. On this graph it shows that with a 5kGy dose which is what we gave our soil sample the survival percentage is 20% our data gives a lower surviving percentage anywhere from 0-18%.

Tuesday was all about grading plates and a little Midterm review. For temperature plates it was surprising the range of growth. The majority of the isolates grew at just about every temperature. What was surprising to me was that at the higher temperatures some organisms changed there pigmentation. I believe this could be temperature affecting the enzymes that typically make these pigments. For salt the range of optimal growth tended to be 0-3% with the few isolates doing well on 6% and only a single one doing anywhere near decent growth on 9%. We received variable results from the isolates that typically grow on MA some did better on R2A with 3% salt than they did on MA alone. Also it was noticed that just because it likes a little salt doesn’t necessarily meant it will grow better at higher salt concentrations.

The most probable reason for the contaminated 1/10th PCA plates was the media was already contaminated before use. This can be deduced by the imbedded colonies in the media.
The Plate picture story is that Salt was not liked at all after irradiation. High nutrients was not favored for numbers or diversity after irradiation. 1/10th PCA was the best to bring around the highest numbers and diversity with 1/100th having high numbers also but not as high diversity.

N97 irradiated soil 10-1 plated on 4 different media and incubated for 20days at 25C:

MA:

PCA:

1/10 PCA:

1/100 PCA: