Artificial biofilm helps double output of microbial fuel cell

Scientists at Newcastle University have isolated 75 different species of bacteria from the Wear Estuary, Country Durham, and tested the power generation of each one using a microbial fuel cell (MFC).

By selecting the best species of bacteria, they were able to create an artificial biofilm, doubling the electrical output of the MFC from 105mW/m³ to 200mW/m³.

While still relatively low, this would be enough power to run an electric light and could provide a power source in parts of the world without electricity.

Among the bacteria was B. Stratosphericus, a microbe normally found in the atmosphere but brought down to Earth as a result of atmospheric cycling processes and isolated by the team from the bed of the River Wear.

Publishing the findings in the American Chemical Society’s Journal of Environmental Science and Technology, Grant Burgess, professor of marine biotechnology at Newcastle University, said in a statement that the research demonstrated the potential power of the technique.

‘What we have done is deliberately manipulate the microbial mix to engineer a biofilm that is more efficient at generating electricity,’ he explained.

‘This is the first time individual microbes have been studied and selected in this way. Finding B.Stratosphericus was quite a surprise but what it demonstrates is the potential of this technique for the future — there are billions of microbes out there with the potential to generate power.’

The use of microbes to generate electricity is not a new concept and has been used in the treatment of wastewater and sewage plants.

MFCs, which work in a similar way to a battery, use bacteria to convert organic compounds directly into electricity by a process known as bio-catalytic oxidation.

A biofilm — or slime — coats the carbon electrodes of the MFC, and as the bacteria feed they produce electrons, which pass into the electrodes and generate electricity.

Until now, the biofilm has been allowed to grow unchecked, but this new study shows for the first time that by manipulating the biofilm it is possible to significantly increase the electrical output of a fuel cell.

Funded by the Engineering and Physical Sciences Research Council (EPSRC), the Biotechnology and Biological Sciences Research Council (BBSRC) and the Natural Environment Research Council (NERC), the study identified a number of electricity-generating bacteria. As well as B. Stratosphericus, other electricity-generating bugs in the mix were Bacillus altitudinis and a new member of the phylum Bacteroidetes.