Comparison with the NCBI database
using a BLAST search revealed that all 63 clones amplified with primers cd3aF:R3cd-GC showed homology
with known nirS sequences. The formation of heteroduplex DNA fragments was not detected in any of the
sequenced clones. All 31 bands except AS5, AS6, AS8
and US4 contained between two and six different clones,
which proves that the fragments did not separate to the