my $ref_db = FastaDb->new($fasta);
while( my $seq = $ref_db->next_seq() ) {
    foreach(@ko_array){
        if($seq->header() =~ m/($_)/){
            open(OUT, ">>".$outdir.$_.".fasta");
            print OUT $seq->header()."\n".$seq->seq()."\n";
            close(OUT);
        }
    }
}