Ya lo solucioné!
<pre> ereg ("([0-9]{4})-([0-9]{1,2})-([0-9]{1,2}) ([0-9]{1,2}):([0-9]{1,2}):([0-9]{1,2})", $time, $datetime);
$ano=$datetime[1]+0; $mes=$datetime[2]+0; $dia=$datetime[3]+0; $hora=$datetime[4]+0; $min=$datetime[5]+0;
$segundos = mktime ($hora,$min,0,$mes,$dia,$ano);
$segundos = $segundos - 18000;
$time = date ("Y-m-d H:m:00", $segundos);
ereg ("([0-9]{4})-([0-9]{1,2})-([0-9]{1,2}) ([0-9]{1,2}):([0-9]{1,2}):([0-9]{1,2})", $time, $datetime);
$ano=$datetime[1]+0; $mes=$datetime[2]+0; $dia=$datetime[3]+0; $hora=$datetime[4]+0; $min=$datetime[5]+0;
</pre>