Posted 23 March 2012 - 08:08 PM
Choose one f primer (such as 27f) and another r primer (such as 1492r) and do pcr. Sequence the resulting band with 27f in one reaction and with 1492r in another. Combine the reads, and blast the sequence.
I'd recommend you read some of the references and consult some of the listed web sites, which will explain the universality of these primers, and likely suggest specific ones for Archaea. Or you could look for the Woese paper in which he discovered the Archaea this way.