Fall 2015 Week 6

This week in lab I ran another sterilization experiment. This time I followed a protocol exactly. I soaked the nightshade leaves in 75% ethanol for three min then in 4% bleach for 5 minutes then ethanol again for 45 seconds. I made nine plates, the more specimens the more data to look at, and have begun to keep careful track of the how things grow on the plates using an Excel spread sheet.

I've found that, once again, within a few days I'm seeing significant fungal growth on all my plates. Its early to know for sure, but I'm pretty sure its the same green-grey mold stuff I've been growing all semester. I'm going to try a few more experiments to attempt to isolate the source of the contamination. I will try plating the tap water I'm rinsing the leaves in as well as test my glassware. I will also think about increasing either the concentration of the bleach or the amount of time spent soaking in the bleach solution.

Another thing I want to try is sterilizing the grass I'm growing that, according to the package, has endophytes in the leaves. If I can isolate endophytes from there I know I'm on the right track.

This is a picture of all the plates I made Spring 2015. They are arranged by decreasing times of sterilization, the first row being 10 minutes and the last being unsterilized. This photo shows that many different kinds of fungi are growing on unsterilized leaves and almost nothing is growing on the longer sterilization times.