from Bio import SeqIO
from Bio.Seq import Seq, SeqRecord
from Bio.Blast import NCBIXML
from Bio.Alphabet import IUPAC


fh = open("/home/local/GLOBANT/sebastian.bassi/Downloads/blastn_elin.xml")

br = NCBIXML.parse(fh)

tofile = []

for record in br:
    for ali in record.alignments:
        for hsp in ali.hsps:
            seq_q = SeqRecord(seq=Seq(hsp.query, IUPAC.unambiguous_dna), id=record.query, name="", description="")
            seq_s = SeqRecord(seq=Seq(hsp.sbjct, IUPAC.unambiguous_dna), id=ali.title, name="", description="")
            tofile.append(seq_q)
            tofile.append(seq_s)
            break

# grabar a fasta
oh = open("output.fasta", "w")
SeqIO.write(tofile, oh, "fasta")
oh.close()