In {HEAD ~ a microbial fuel cell}, {TAIL ~ the transgenic microbes} have access to a feedstock 
In { HEAD ~ a microbial fuel cell } , { TAIL ~ the transgenic microbes } have access to a feedstock
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH