enviromental water samples DNA isolation - (Feb/26/2014 )

Sorry for my English, I am having a problem with DNA isolation from environmental water samples using the PowerWater DNAIsolation Kit sample (MOBIO). When I filter samples after treatments (herbicide addition) but before start the isolation, a mucous film keep on the filter (0,22 µ), probably a polysaccharide or something made for microorganisms, and it is impossible the DNA isolation. What could you suggest me to solve the problem?

you can try filtering through a more porous filter (eg whatman #1 filter paper) to remove macro contaminants prior to 0.22um filtration.

You may then consider your sample as a biofilm... some microalgae and cyanobacteria produce a thick EPS layer

What's the volume you filter? If the volume is small, e.g. 50 mL, you can try to vortex the sample at high speed for a while, it can make the EPS layer separate and make it easier to filter. If you have bigger volumes you can try sequential filtering through different pore sizes and do the extractions separately to avoid losing any component. Other alternative is recovering the biomass by centrifugation and/or digesting the EPS (enzimatically?)