As part of our
commitment to the highest level of customer service, Gerard Biotech
asks our customers to fill out a survey. Using this information,
we can evaluate the effectiveness of our products and determine
how we can continue to provide the best products and service on
the market. Below is an email resonse we received as part of a broadcast they made to their lab.
Wanted to let you know how the Hurricane Maxi Prep kit from Gerard
Biotech turned out. We can't get higher concentrations than the
Quiagen kit, but we get a lot more DNA per unit volume of culture*.
It also takes about half the time of the Quiagen kit, 2 hours for me
versus 4. It's also a lot cheaper at $10.50/prep versus $14.45/prep
for the Quiagen kit.
That's the abstract, the rest is details.
The recommended culture volume is 200-300 ml, so I split Nisha's 500
ml culture in half and ran it in duplicate. The yield was 1.7 mg/ml
in ~1 ml, so we're getting up to 5 times more DNA than with the
Quiagen kit (Some I've done are that same concentration, but in only
200 ul, and used 500 ml culture). Previously with the Quiagen kit
for that plasmid, we got 0.6 mg/ml (not sure what volume, but
probably 400 ul).
Nisha wanted to try a test to get the maximum concentration. The kit
protocol is 1 ml of buffer preheated to 70 degrees (which elutes ~70%
of the DNA) followed by another 1 ml to try to elute the rest. Tech
Support at Gerard Biotech suggested we could re-use the first aliquot
in the column to elute again. We also tried eluting in just 500 ul,
followed by 1 ml.
1 ml re-used 1.7 mg/ml (NOTE: only 250 ml culture and in 1 ml, not 200 ul)
500 ul 1.7 mg/ml
1 ml after 500 ul 0.8 mg/ml
Note that the small volume first sample yielded about the same amount
of DNA in a bigger combined volume. The follow-up 1 ml was at 70
degrees for that sample. The re-used eluate had time to cool down
during the 5 minute RT spin.
I might have been able to improve the yield more if my 70% ethanol
had been ice cold instead of room temp.
I had no problems whatsoever using the lower 3000 xg swinging bucket
centrifuge rather than the 5000 xg the protocol called for. I did
not have to increase the spin time over the recommended protocol to
completely empty the DNA binding cup of fluid.
On an interesting side note, we seem to have exceeded the rated
binding capacity of the tube (up to 1.2 mg) by getting 1.7 mg of DNA.
If you have no objections, I'll start ordering the Gerard Biotech
kits intead of the Qiagen kits.
*Carolyn was just commenting on how much LB the
labs use and that it cost $6000 for the Center last year. We could
reduce our culture volumes to 250 ml or just get more DNA at a time
and run fewer cultures.