Mystery of the Microbes

How can it be that members of a totally new microbial species have been found in two completely separate places on Earth (Florida and French Guiana) and nowhere else? And how can it be that these microbes were found in rooms that are purposely kept immaculately clean?: http://www.jpl.nasa.gov/news/news.php?release=2013-319&utm_source=iContact&utm_medium=email&utm_campaign=NASAJPL&utm_content=releases20131106