use strict;
use Bio::SeqIO;
use Data::Dumper;

my $filename="swiss-prot.dat";
my $sequence_object;

my $seqio = Bio::SeqIO -> new   (
                                '-format' => 'swiss',
                                '-file' => $filename
                                );

while ($sequence_object = $seqio -> next_seq) {
#print Dumper($sequence_object);
my $sequentie = $sequence_object-> seq(); 
print $sequentie."\n";
#last;
}