I am running the EPA's method 1611: Enterococcus qPCR assay for recreational beach water quality management (is anyone else out there giving this a try?). But my seawater samples keep coming back with extremely high inhibition (as shown by the Sketa internal control, as suggested by the EPA protocol). Inhibition must be coming from the seawater samples, although I'm not sure what exactly is causing the inhibition.
I am already using BSA at a final concentration of 1mg/ml. Can I increase the BSA concentration? Is that likely to help? What about adding betaine or DMSO? What concentrations should either of these be used at? Can/ should they be used together and/or with BSA? Or should I do one at a time? Are there any other additives that people out there have had success with? Or any other suggestions for dealing with inhibition?
Thanks for the help!