use strict;
use warnings;

$\ = "\n";
$, = ', ';


my %results = ();
while (<DATA>) {
    my @pieces = split /\s+/;
    my $id = $pieces[0];
    my $seq = $pieces[-1];
    $results{$id} = [] unless exists $results{$id};
    push @{$results{$id}}, $seq;
}

foreach my $key (keys %results) {
    my $arr_str = join ',', @{$results{$key}};
    print "$key -----> [$arr_str]";
}

__DATA__
HWUSI-EAS548:7:1:5:1527#0/1  + chr12  52084152 CGGAGC
HWUSI-EAS548:7:1:5:1527#0/1  + chr12  52084152 XXXXXX
Some_other_id  + chr12  52084152 CGGAGC