On Mon, Mar 4, 2013 at 5:20 PM, Ivan Gregoretti <ivangreg at gmail.com> wrote: > I am trying this > > from Bio import SeqIO > SeqIO.FastaIO.FastaWriter( handle, wrap=0 ).write_file( record ) > That should be a list of SeqRecord objects, not just one SeqRecord. If you have just one, try [record] instead. Peter