Qiagen mini prep cell fragment pellet - (Jul/03/2013 )
I fund when using the Qiagen miniprep kit, after lysis and then neutralisation with N3, that the cell debris I get is impossible to pellet. It forms a weird semi-solid that floats between what seems to be two different phases. It really limits the amount of supernatant I can get.
I remember experiencing this before but it's particularly bad at the moment for me. Any advice much appreciated.
Ensure that you mix the lysis and neutralization buffers well, spin at greater than 10,000 RCF.
This can be caused by large pellets. You may want to reduce the volume of cells, or grow in LB instead of a rich medium.
You can always filter with a coarse pore filter, such as cheese cloth.