How do I deal with sticky and viscous samples from cell lysates? To check a protein expression I pelleted a small amount of _E. coli_ before and after induction and lysed them by redissolving them in SDS-PAGE loading buffer and heating them to 95 °C for 1 minute. This lead to a solution with some very sticky and viscous parts in it, that make pipetting the sample into the gel wells extremely annoying. As far as I heard, this is probably genomic DNA, and my usual way to deal with this is to centrifuge the samples and only pipet a small part out from the top. This does seem to help sometimes, but not always. How can I avoid the formation of that sticky and viscious stuff or how can I avoid pipetting that stuff into my wells?

Yes, it is the genomic DNA that is causing you trouble. Although a brief 1000g spin should bring it all down, the pellet is never tight and you almost always are going to pull up some gunk with the clear supernatant. A better solution is to include a quick sonication step (5-10s) before the 1000g spin. That way, the DNA is sheared and it should pellet better. It has worked for me most times. Also, remember to use a reasonable volume of SDS buffer when you lyse the cells. Too little buffer and its always going to be hard. For comparison, I use about 200ul per 1ml culture pellet and this volume works well for both pre- and post-induced cells.