Research Assistant Professor

Microbial Fuel Cells-Biology

Contact Info

Office:106A Morrill IVN
Phone:413-545-9782
email:aefranks@microbio.umass.edu

Education

  • PhD. Microbiology, University of New South Wales, Sydney, Australia.
  • B.Sc. Hon. Microbiology and Immunology, University of New South Wales. Sydney, Australia.

Research description

Applied environmental microbial ecology continues to uncover an amazing range of processes with beneficial applications. My research encompasses microbial biofilms and the interactions that occur within these biofilms. In particular I am interested in the ability of bacteria to accept and donate electrons extracellularly to solid surfaces. Electron transfer allows bacteria to electrically interact with a wide variety of surfaces and compounds. One well-known application of extracellular electron transfer is microbial mediated power production using a Microbial Fuel Cell. In a Microbial Fuel Cell, bacteria are able to convert a wide variety of organics and wastes into an electrical current in a self-sustaining no polluting fashion. Not only are bacteria able to produce an electrical current in a microbial fuel cell bacteria are also able to consume electrons. When consuming electrons the bacteria are able to reduce a range of organic and inorganic compounds into a variety of useful products.

Microbial biofilms are fundamental to electron transfer to and from a electrode surface. My research has encompassed several different aspects of microbial biofilms attached to an electrical conductive surface. This research has furthered our understanding of the structure and function of these specialized biofilms through basic research. This research is fundamental to future improvements of these microbial electric systems,

To overcome treating the biofilms as a “black box” I have developed a number of novel techniques. I developed a microbial fuel cell that allows real time non-destructive imaging of the current producing biofilms. Red and green fluorescent protein expression vectors were created to allow fluorescent imaging of the Geobacter species during biofilm development and power production. To improve the stability the fluorescent protein encoding genes where incorporated into the genome allowing continuous imaging of the bacterial cells during power production allowing for investigation of the structure and function of the biofilm. Metabolic stains, CTC and redox green, demonstrated activity through out the biofilms and application of the pH sensitive of fluoroprobe, C-SNARF-4, demonstrated a decrease of one pH unit in the biofilm, from a pH of 7 in the bulk fluid to 6 at the biofilm base. Interestingly, the growth rate of Geobacter was maximum at a pH of 7 but is significantly reduced at a pH of 6. Further investigation demonstrated that power production could be briefly increased or decreased through manipulation of the bulk fluid pH. Proton production by G. sulfurreducens, while using an anode as an electron acceptor, may be a current bottleneck in power production.

To investigate global spatial differences in transcription between the inner and outer biofilm members a novel system to embed, slice, pool and collect RNA from the current producing biofilms has been developed. This technique has allowed for the collection of enough RNA, from the inner and outer sections of a single biofilm, for the first time to conduct microarray analysis of global changes in transcription within two separate layers of a biofilm. Many changes have been observed between the inner and outer biofilm members. These microarrays have provided novel targets for my future research. To confirm the spatial arrangement of the gene expression, short half-life green fluorescent proteins are being placed under the control of the promoters of the genes of interest from the microarrays.

While much research has focused on the production of power in microbial fuel cells, the ability of bacteria to transfer electrons to and from a conductive surface has many environmentally favourable applications. In addition to electron transfer onto an insoluble electron acceptor, Geobacter species can use negatively poised electrodes as electron donors for reduction of fumarate, nitrate, and Uranium (VI). This research has been expanded to include dechlorinating microorganisms, capable of metal-reduction, for the reduction of chlorinated ethenes and chlorinated aromatic compounds using a negatively poised electrode as the electron donor. These processes have important implications for bioremediation

Invited Oral Presentations

  • Metabolism and electron transfer through conductive Geobacter sulfurreducens biofilms. Naval Research Laboratory, Washington, USA, 2010.
  • Electro-biotechnology, New avenues for bioenergy and electric biofilms. Institute of Biological Engineering, Boston, USA, 2010
  • Combining applied environmental microbiology and bioelectric systems for bioremediation and the production of green energy. Microbiology Symposium, West Point Military Academy, USA, 2009.
  • Structure and function of bacterial biofilms associated with bioelectric systems. British Society for General Microbiology, Bioenergy Fuel Sources Conference, Edinburgh, Scotland, 2009.

Conference Roundtables

  • Extracellular electron transfer – A versatile environmental process with many applications other than power generation. Co-Chairs Ashley Franks and Sarah Strycharz. 12th International Symposium of Microbial Ecology, Cairns, Australia, 2008.

Selected Publications

  • Nevin, K.P., T.L. Woodard, A.E. Franks, Z.M. Summers, and D.R. Lovley. 2010. Microbial electrosynthesis: feeding microbes electricity to convert carbon dioxide and water to multicarbon extracellular organic compounds. mBio 1(2).
  • Franks, A.E., Malvankar, N., and Nevin, K.P. (2010) Bacterial Biofilms, The Powerhouse of a Microbial Fuel Cell. BioFuels. Jul.
  • Franks, A.E., and Nevin. K.P., (2010) Advances in Microbial Fuel Cells, a Current Review. Energies. 3(5), 899-919.
  • Franks, A.E. (2010) Transcriptional analysis of current producing biofilms, the pitfalls of microbes in diverse physiological states. FEMS Letters. In press
  • Franks, A.E., Nevin, K.P., Glaven, R. and Lovely, D.R. (2010) A Novel Approach for Spatial Analysis of Global Gene Expression within a Geobacter sulfurreducens Current-Producing Biofilm. ISME J 4(4):509-519..
  • Williams, K.H.,. Nevin, K.P. Franks, A. Englert, A. Long, P.E. and Lovley, D.R. 2010. Electrode-based approach for monitoring in situ microbial activity during subsurface bioremediation. Environmental Science and Technology 44(1):47-54.
  • Yi, H., Nevin, K. P., Byoung-Chan, K., Franks, A. E., Malvankar, N., Haveman, S. A. and D. R. Lovley. (2009) Selection of a Variant of Geobacter sulfurreducens with Enhanced Capacity for Current Production in Microbial Fuel Cells. Biosensors and Bioelectronics. 24(12):3498-3503.
  • Named 20th Best Invention of 2009, Time Magazine.
  • Zhang, T., Nevin, K.P., Franks, A.E., FitzPatrick, S.M. and Lovley., D.R. Accelerated Oxidation of Toluene with Electrode-reducing Geobacter metallireducens. Environmental Microbiology. In press
  • Strycharz, S., Gannon, S., Boles, A., Franks, A.E, Nevin, K., and Lovley, D. Reductive dechlorination of 2-chlorophenol by Anaeromyxobacter dehalogenans with an electrode serving as the electron donor. Environmental Microbiology and Environmental Microbiology Reports. In press
  • Franks, A.E, Nevin, K. P. Jao, H,. Izallalen, M., Woodard, T. and Lovley D. R. (2009) Novel Strategy for Three-Dimensional Real-Time Imaging of Microbial Fuel Cell Communities: Monitoring the Inhibitory Effects of Proton Accumulation within the Anode Biofilm. Energy and Environmental Science. 2:113-119.
  • Nevin, K. P., Byoung-Chan, K., Glaven, R. H., Johnson, J. P., Woodard, T. L., Methé, B. A., DiDonato. R. J., Covalla1, S. F. Franks, A. E., Liu, A. and Lovley, D. R. (2009) Anode Biofilm Transcriptomics Reveals Outer Surface Components Essential for High Density Current Production in Geobacter sulfurreducens. Fuel Cells. PLoS ONE 4(5):e5628.