Field of Science

Back in the lab, at least briefly

The last few weeks I've been in teaching-zombie mode, with my brains sucked dry by 350 second-year genetics students.  But I've only 4 more classes to go (each taught twice) and this morning I went into the lab and cleaned up all the glassware from the last three or four experiments.  Now I'm ready to start a new one.

This is a very unambitious experiment, the next tiny step in solving the "Why won't GFAJ-1 grow consistently in 40 mM arsenate?" problem.  In previous experiments the cells grew well with arsenate in small glass screw-cap tubes (now soaking in preparation for future re-use), but my DNA preps will need much larger volumes (500 ml or more), because cells can't grow to high density when phosphate is limiting (duh).  So now I'm going to try growing them in glass flasks with and without 40 mM arsenate.  I'll grow them on the communal shaker in the 30 °C room rather than in our spare shaker since our shaker is needed for other experiments.

So:  250 ml glass flasks (I have 6 sterile and ready to use), with 20 ml of AML60 medium with glucose, glutamate, and added phosphate at 0, 3 µM and 1500 µM, with and without 40 mM sodium arsenate.  All inoculated with phosphate-limited GFAJ-1 cells from my freezer stock, at about 10^4 cfu/ml.

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