I am looking to purify mRNA from Staphylococcus aureus, primarily to analyse expression using qRT-PCR. I am using the Qiagen RNeasy mini-kit with an added lysostaphin step to improve lysis. This process is followed by DNase treatment with the DNA free kit from Ambion. I am often getting poor RNA purification (in terms of quality) from this approach particularly from stationary growth phase cells along with a lot of DNA contamination which is masking the expression levels of my gene of interest. I was wondering if anyone had any alternatives to this approach such as other kits or tips on how to improve this kit?
Many Thanks!