For credible DNA preps I need reproducible growth with and without 40 mM arsenate, and I need to be able to grow large volumes because the cultures with only 3 µM added phosphate won't reach a very high density and thus won't yield much DNA per ml.
One practical limitation to my GFAJ-1 experiments is that it's optimum growth temperature is 28 °C but we only have two shaking water-baths, one that's always at 37 °C and one that currently often needed at 30 °C. But Halomonas bacteria typically tolerate a wide range of growth temperatures, and there's 30 °C room down the hall with shakers in it. So tonight I'm setting up pairs of replicate cultures without arsenate, one to shake at 28 °C and one to shake at 30 °C. If they grow at about the same rate and to the same density I'll do my growth tests in the 30 °C room and only switch to our own shaking water-bath at 28 °C when the arsenate-resistance problem has been sorted out and I'm ready to generate good growth curves and DNA preps.
So... Make up a fresh batch of medium, add cells from a freshly thawed tube of GFAJ-1, and put into replicate flasks with different amounts of phosphate. Do I have enough glass flasks? Yes, there are 12 on the sterile-glassware shelf.
Why I'm Marching for Science
1 day ago in Angry by Choice