$re = '/Additional Info:\s*(?<AdditionalInfo>[^\"]*)/m';
$str = 'string input= "status":404,"userMessage":"ERROR CODE: EBE04005 | SEVERITY: E | SOURCE IDENTIFIER: EBE04 | DESCRIPTION: The User Profile Retrieval Service was unable to process due to an unavailable Data Source: | Additional Info: Prodcucer Detail Not Found In Producer DB For Producer Code: 123456"} ';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php