DNA extraction from BAC

[Zhongtang Yu]

Dear netters.
I am trying to extarc DNA from a biological activated carbon (BAC) which  
is from a biological wastewater treatment plant.  There is ton of microbes  
(mixed community) but I always get a very low yield when I extract DNA  
from this BAC.  Microscopy showed that the cell lysis was quite complete  
after lysozyme and freezing-thawing. Another experiment showed that fresh  
activated carbon (without biofilm on the carbon particles) could adsorb  
85% of the DNA in solution. No way to seperate the powdered carbon  
particles and the microbial cells. Phenol does not desorb the adsorbed DNA  
from the BAC though it can be adsorbed by activated carbon strongly.    
Does any one have experience in extracting DNA from biologi al activated  
carbon? 
       
Thanks.