This article is from last summer, but I just came across it and thought I would share)

...Dr Ieropoulos will take the concept of the Microbial Fuel Cells to the next level with a new team of researchers. They will work on scaling up the MFCs so that they can work together in a 'stack' -- a series of cells which are connected both electrically and in terms of the liquid feed-lines under a continuous flow system. Developing this will present a challenge for the researchers, as the liquid must be in a continuous flow, but still allow individual MFCs to remain isolated. However a stack of linked MFCs will be much more efficient and produce more energy than the same number of individual MFCs.