Cometabolism is generally defined as the simultaneous biotransformation of a primary energy source, such as methane, and {HEAD ~ a secondary chemical species}, such as {TAIL ~ chlorinated alkenes} 
such as
Cometabolism is generally defined as the simultaneous biotransformation of a primary energy source , such as methane , and { HEAD ~ a secondary chemical species } , such as { TAIL ~ chlorinated alkenes }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL