Methane is an organic carbon compound containing the fundamental building block of nearly all living material: carbon. It provides an important source of energy and nutrients for bacteria. Methane is produced in oxygen-free environments and is found in abundance at the bottom of lakes.  Please continue reading at: 
http://www.sciencedaily.com/releases/2012/08/120827074226.htm
http://www.sciencedaily.com/releases/2012/08/120827074226.htm