This fragment persisted
even when samples were re-digested with excess enzyme (HphI).
The dominant OTU in most biofilters at the start of the experiment,
was represented by a TRF of 107 bp (a 485 bp TRF was dominant
in biofilter B, and a 337 bp TRF was dominant in biofilter D). This
107 bp OTU eventually disappeared from the flood/drain biofilters,
but persisted in the submerged biofilters, being present in all submerged
biofilters in treatment 3. In the flood/drain biofilters the
OTU with a TRF of 337 bp appeared to increase at the expense of
that with one of 107 bp.