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24.10.11

All you (n)ever wanted to know about a bacteria you've never heard of

To summarize: this is a lengthy post on something that will never affect you about my adventures in a windowless room over the summer.



This Summer I was accepted to participate in an on-campus internship sponsored by the Howard Hughes Medical Institute. The internship was "eleven" weeks long starting early July and ending with a symposium in September. I started Spring Term and probably will not end until... I don't know.

The lab I work in is a Microbiology lab run by Dr. Stephen Giovannoni. The lab studies a marine bacteria named 'Candidatus Pelagibacter ubique' but called SAR11.

There are several "isolates" of SAR11. Different sub-species within a species. Think of it as different ethnicities. Humans have asians, europeans, islanders, etc. SAR11 has HTCC1062, 7211, 1002, 2155, 2181 etc. HTCC is a way to specify that a specific isolate is being referred to and specifies the way the culture is grown. I work with three of these isolates 1062, 7211, and 1002.

Due to its dominance it is important in the role of carbon cycling in the ocean. Carbon in the atmosphere is fixed by autotrophs in a process called photosynthesis. SAR11 then takes the byproducts (mainly sugars) and oxidizes the carbon releasing it into the atmosphere as CO2 (think green house gas).

The open ocean is much like a desert (aside from water). It contains sparse quantities of key nutrients needed to survive (Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Sulfur). Thus, the organisms that live in the ocean have to compete for the nutrients available.

I specifically studied the types of phosphorus containing compounds SAR11 is able to utilize to alleviate phosphorus limitation. I did this by growing the strain in a phosphorus-limited media. The strain was then divided into a series of flasks. To each flask a test compound was added; in addition there was a positive control (had a usable phosphorus source) and a negative control (no phosphorus).

Here is a clip from my presentation, in it I summarize the above as well as present the data I collected. You can't hear me that well so turn up the volume.

http://www.youtube.com/watch?v=xRPIP1-hXnk

It was a neat experience. Now all I have left is a lot more testing and to write the paper summarizing my results.

3 comments:

  1. I am lucky to have a really smart wife =)

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  2. Dear Emily, Excellent presentation. It was easy to follow especially the graphs. The last diagram that summarized the "domains" really hit the findings clearly. The one thing that it took me a while to follow was how you could claim when the growth was double the control. I finally eyeballed the y axis which was in increments of e power.
    Dr. Eldon Olsen

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  3. Sorry, the power point was slightly cut off so you could not read my labels.
    The Y-axis was the logarithmic count of the cells in Cells/mL.
    The X-axis was Time in Days.

    Thank you for your comment!

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