Extraction of DNA from polysaccharides-rich matrix - (Sep/23/2006 )

I am trying to do DGGE on biomat to find out microbial community structure.
I am having a problem when I tried to extract DNA from cyanobacterial biomat.
This biomat is packed with bacteria, cyanobacteria, polysaccharides produced by these organisms.
I think that large amount of polysaccharides prevent DNA extraction.
Does anyone have a way to efficiently extract DNA from carbohydrate rich biomat?
Thanks!

should'nt polysaccharides be removed by centrifugation as other cellular contaminants!!