Subject: What kind of bacteria decompose animal wastes into methane gas?

I am interested in the use of anaerobic methanogens as a method of converting 
feces/organic wastes into an easily collectable form of methane gas. I know 
bacteria similar to this are found in our intestines. Would these work outside 
of the environment in our intestines? If not, are there bacteria that perform 
similar functions that would? Where can I obtain a sample of such a bacteria? 

Re: What kind of bacteria decompose animal wastes into methane gas?