Hi Philip, I recently had to make the switch to the fast kit version as well for the same reason. I've had about the same success with both kits. I'm amplifying microsatellites from fecal DNA. I can't make the comparison for total gDNA yield (I stopped quantifying my DNA since its always low and made no difference in my reactions), but I can tell you that it works!

Thank you Vicki! I was concerned as I had obtained pretty good yields by modifying the protocol of the older kit slightly. I know that you said that you haven't recorded any of the yields obtained using the new kit, but would you be able give a rough estimate? I am extracting gDNA from fish gut content to examine the microbial communities therein., and would usually obtain anywhere from 50-300 ng/ul yield using the old kit? More often than not the yield would be on the lower end of this scale

I'd say I always get less than 50 ng/ul, but my samples are pretty degraded due to my sampling habitat. My DNA never shows up on 1% gels, so I know its really low (same story for both kits). Best of luck!

Thanks Vicki. My DNA sometimes shows up on gels, but is pretty degraded and is far from a strong band. I appreciate your help on this as I will be taking samples to use with the new kit very shortly. Cheers

We have also been having bad luck with the InhibitEX solution from the Qiagen  Stool DNA Extraction kits (Catalog # 51604).  When we compare the two kits, the quality and quantity of the genomic DNA extracted from stool is much poorer (more smeared and lower yield) and doesn't pass our QC standards compared to the genomic DNA extracted using the kit with  the InhibitEX tablet (Catalog #51504). 

We are also facing the same problem with the new Qiagen Fast kit (Cat 51604). Could anyone help me how to rectify the problem?

Thank you.

Hi Philip!

since i am using the same kit of QIAamp and getting very low DNA concentrations from my neonatal stool samples, could you please give me an idea about the modifications you are doing on the kit. I never got 30ng/ul!

With my samples i have found that after adding the buffer it is advisable to incubate it overnight at 56 deg cels

Recently I tried using the  "Fast DNA Stool Mini Kit" to extract DNA from chicken caecal samples however when I ran samples on a gel I saw very low levels of DNA. Switching to the older stool kit with the InhibitEx tablets really helped to improve my yield (quantified roughly by running out on a 0.8% gel)

QIAGEN recently released a QIAamp PowerFecal DNA Kit that has a more powerful inhibitor removal technology. I don't know if it will help with yields, but it puts a larger % of the lysate on the column, so I think it very well might! Hope that helps.

Philip,

I tried Qiagen's DNA Stool Mini Kit for extraction of gDNA from coccidia parasites in 2015. The kit included the InhibitEx buffer however, It did not work for me. I spend four months trying to figure out why it was not working on. I tried with different number of parasites, change the time of incubation (the first step) but nothing worked. So, I asked to other users and the supplier about the problem. I was not the only with the same problem (you can find their questions and answers here in RG). It supposedly was a set of defective kits. I do not have idea if it is working well right now. I hope so. Good luck.  

I have been using the Qiaamp Fast Stool mini kit, and have been quite satisfied with it... Both when looking at DNA quality, yield and ability to perform other analysis afterwards (PCR and 16s rRNA sequencing). 

However, as Sünje also descriped, we found that inclusion of bead-beating improved the outcome, especially for the gram positive samples.

I have,however, not used the previous kit, with tablets before, so I am unable to compare the two kits. 

Do you know the recipe to make the "Proteinase K" and "AL" b uffer in house Sünje Johanna Pamp ?

I am using the Qiaamp Fast Stool mini kit, it is working fine, even inhibitX buffer works better than tablets. I usually get the yield about 1-2ug of DNA.  You can just modify it by increasing the incubation time and at every incubation step you must vortex your sample continuously. For this i am using

Eppendorf ThermoMixer® C .