A study of metagenomics-informed biochemical functionality of microbial fuel cells using DDGS as a substrate

Lead Research Organisation: University of Surrey
Department Name: Microbial & Cellular Sciences

Abstract

This proposal addresses a BBSRC initiative that aims to enhance the value of Dried Distillers Grains with Solubles (DDGS), a byproduct of grain-to-bioethanol and whisky production. DDGS will become increasingly abundant in the UK as bioethanol production develops. It is currently mainly used as a cattle feed but there is also interest in developing it as an industrial feedstock

A microbial fuel cell (MFC) is a device that contains an anerobic culture of microorgnaisms, capable of directly converting chemical energy to electrical energy. A typical microbial fuel cell consists of anode and cathode compartments separated by a cation (positively charged ion) specific membrane. In the anode compartment, nutrients are oxidized by microorganisms, generating electrons and protons. Electrons are transferred to the cathode compartment through an external electric circuit, while protons are transferred to the cathode compartment through the membrane. Electrons and protons are consumed in the cathode compartment, combining with oxygen to form water.

We will develop a microbial fuel cell that will process DDGS prior to drying and use as an animal feed. The MFC will generate electricity (to reduce consumption by the biorefinery) and enhance the protein content of the animal feed product.

The species of micro-organisms added to the MFC will be determined by analysing all of the genes present in whole populations of micro-organisms (metagenomics) under a range of conditions and using a computer simulation which highlights the most important genes to carry out the desired functions of the MFC. The population composition will be further fine-tuned by feeding the microbes with nutrients as rewards for achieving the desired characteristics, forcing it to evolve to the most effective distribution of species.

Technical Summary

We will study the use of DDGS as a substrate for electricity generation using Microbial Fuel Cells. We have already tried this out and proved that it is possible and studies elsewhere using similar substrates provide confidence that this is a viable project with a high probability of success. In addition to addressing the pragmatic objective, implicit in this initiative, we will address important scientific questions, that will lead to publications in high-impact journals. We will test the hypothesis that maximum electrical output from a MFC is dependent on the biochemical capability of the population rather than on the identity of the individual species present in the MFC community. In doing so we will employ metagenomic analysis of the microbial community within the MFC, both in the anodic biofilm and in the anodic suspension, in order to relate the presence of critical genes in the population to the electrical output of the bioelectrochemical system. Extending this philosophy, we will carry out forced evolution of the microbial population by using the power output to modulate the nutrient feed rate to the MFC.

The metagenomic study will be used to construct a metagenome-scale metabolic model, a novel development in the field of metagenomics that is likely to lead to a high profile publication. The model will be used to investigate the effect of changes in the population during forced evolution and to predict the optimal metagenome needed to carry out this particular function

In addition to generating electricity, we plan to evaluate the production of hydrogen using a variation of the MFC concept (microbial electrolysis cell).

Our approach could be applied equally to raw DDGS or DDGS that has undergone any form of secondary processing.

Planned Impact

Potential impact of microbial fuel cells on biorefinery operation

(Many of these issues were raised by the Steering Group during assessment of the preliminary application.)

A suitable bench-mark objective would be to produce sufficient electricity to power the electric stirrer motor for the process bioreactor.

The power requirement for mixing a bioreactor is1-2kWm-3 (Doran PM (1995) Bioprocess Engineering Principles, AP). Hitherto, the highest reported MFC output is 1.55kWm-3 (Fan et al, 2007Env Sci Tech 41:8154-8) so this is an achievable objective for this technology. Our study will show the extent to which this ideal scenario can be met with DDGS and provide a benchmark for the utility of bioprocess MFC waste treatment that can be employed throughout the industry.

We also intend to study hydrogen generation by operating the MFC vessel as a microbial electrolysis cell. A recent study has concluded that, at a cost of $4.51/kg H2 for winery wastewater (a similar substrate to DDGS) and $3.01/kg H2 for domestic wastewater the cost is less than the estimated merchant value of hydrogen ($6/kg H2) (Cusick et al, 2010, Int J Hydrogen Energy.35 8855-61). Although electricity generation is our primary objective, hydrogen production could offer a useful alternative application for this type of technology, without compromising the value of DDGS as an animal feed. Efficient electricity production and hydrogen production are, however, mutually exclusive.
 
Description We have shown that a natural microbial community can be used to obtain electricity from DDGS (a by-product of the bio0ethanol industry) for powering small appliances, sensors, etc. After the process, DDGS has been improved as an animal feed, as many indigestible components are degraded.

We have developed a cascade of bioreactors that can be tuned to maximise the output (and by extension, to focus on particular sub-products such as chemicals and precursors).

The academic outcomes are of extreme importance for microbial metabolism and ecology. We have developed metabolic models for microbial consortia, we have contributed to the elucidation of the understanding of metabolic processes linked to electrogenesis, and of ecological mechanisms involved in the formation and self-organisation of microbial communities. We have made some advances in the understanding of mechanisms of extracellular transport in microbial species (e.g. Bacillus).
Exploitation Route Our results are at laboratory scale. These could be scaled up to pilot- or industrial-scale.

It should be possible to test the nutritional improvement of DDGS.

It should be possible to adapt a bioelectrochemical system within a bioethanol plant to power small appliances or remote sensors.
Sectors Agriculture, Food and Drink,Chemicals,Energy,Environment,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology

 
Title Cascade MFC 
Description A cascade of microbial fuel cells was developed to evaluate the self-organisation of microbial communities and the improvement in the utilisation of complex substrates for the production of bioenergy and bioproducts. 
Type Of Material Technology assay or reagent 
Provided To Others? No  
Impact This device could be adapted to study digestibility of feedstocks using other type of microbial communities (e.g. animal or human gut microbiomes). 
 
Title Plug flow MFC 
Description A novel, multi-electrode, plug-flow Microbial Fuel Cell for utilization of substrates with high solid content. Although designed to carry out experiments with a particualr substrate (DDGS), this could be adapted for end of pipe energy recovery from any organic waste stream. 
Type Of Material Technology assay or reagent 
Provided To Others? No  
Impact This tool has been designed and tested to replace MFCs in series, unable to hold slurry materials. The device is still under trial runs. 
 
Title Metabolic models MFC 
Description A collection of metabolic models for microbial species present in microbial fuel cells inoculated with natural microbial communities 
Type Of Material Computer model/algorithm 
Year Produced 2014 
Provided To Others? Yes  
Impact The models were used in related projects for the analysis of results from other experimental systems 
 
Description Consortium Industrial Biotechnology 
Organisation Jacobs University Bremen
Country Germany, Federal Republic of 
Sector Academic/University 
PI Contribution Led and co-ordinated multidisciplinary ERA CoBiotech submission, consisting of 7 groups from EU and South America. My contribution is in the field of bioinformatics, metabolic modelling, systems microbiology.
Collaborator Contribution Groups provided expertise in Chemistry (Bremen), Solid feedstock MFCs (Poland), liquid feedstock MFCs (Italy), Scale up (Argentina), Life Cycle Analysis and sustainability (Norway)
Impact No outputs or outcomes yet. Disciplines involved: Microbiology, Chemistry, Biochemistry, Bioelectrochemistry, Environmental Engineering, Industrial Biotechnology.
Start Year 2017
 
Description Consortium Industrial Biotechnology 
Organisation National Institute of Industrial Technology
Country Argentina, Argentine Republic 
Sector Public 
PI Contribution Led and co-ordinated multidisciplinary ERA CoBiotech submission, consisting of 7 groups from EU and South America. My contribution is in the field of bioinformatics, metabolic modelling, systems microbiology.
Collaborator Contribution Groups provided expertise in Chemistry (Bremen), Solid feedstock MFCs (Poland), liquid feedstock MFCs (Italy), Scale up (Argentina), Life Cycle Analysis and sustainability (Norway)
Impact No outputs or outcomes yet. Disciplines involved: Microbiology, Chemistry, Biochemistry, Bioelectrochemistry, Environmental Engineering, Industrial Biotechnology.
Start Year 2017
 
Description Consortium Industrial Biotechnology 
Organisation Norwegian University of Science and Technology (NTNU)
Country Norway, Kingdom of 
Sector Academic/University 
PI Contribution Led and co-ordinated multidisciplinary ERA CoBiotech submission, consisting of 7 groups from EU and South America. My contribution is in the field of bioinformatics, metabolic modelling, systems microbiology.
Collaborator Contribution Groups provided expertise in Chemistry (Bremen), Solid feedstock MFCs (Poland), liquid feedstock MFCs (Italy), Scale up (Argentina), Life Cycle Analysis and sustainability (Norway)
Impact No outputs or outcomes yet. Disciplines involved: Microbiology, Chemistry, Biochemistry, Bioelectrochemistry, Environmental Engineering, Industrial Biotechnology.
Start Year 2017
 
Description Green Biologics 
Organisation Green Biologics
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Private 
PI Contribution We have provided samples of the microbial communities evolved in the MFCs that showed enhanced production of biosolvents.
Collaborator Contribution The strains were isolated and analysed for biosolvent production.
Impact Analysis still ongoing. No reportable outcomes yet.
Start Year 2015
 
Description MFCs for coffee feedstock 
Organisation University of Antioquia
Country Colombia, Republic of 
Sector Academic/University 
PI Contribution Design of system for treatment of waste for coffee industry
Collaborator Contribution experimental work, materials
Impact No outcomes yet
Start Year 2016
 
Description Microbial Ecology of Wastewater Treatment 
Organisation University of Surrey
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Academic/University 
PI Contribution Collaboration with research in the analysis of the microbial composition of microbial communities in water treatment plants.
Collaborator Contribution A PhD student (supported by Thames Water) carried out the year-long experiment and supplied microbial community samples
Impact Two manuscripts submitted for publication
Start Year 2014
 
Description Parthenope University of Naples 
Organisation Parthenope University of Naples
Country Italy, Italian Republic 
Sector Academic/University 
PI Contribution Dr Rosa Nastro, a researcher from the Parthenope University of Naples, spent three months at the University of Surrey. During this period, Dr Nastro performed experiments using DDGS as a substrate in bioelectrochemical systems using strains isolated from her own research in Italy. We contributed with technical and theoretical advice, and the experimental set-up for the analysis.
Collaborator Contribution Dr Nastro supplied strains with proven electrogenic activity, which were used in our MFC cascade systems to test the resilience of natural communities towards invasion of exogenous species.
Impact Presentation of paper: Utilization of agro-industrial and urban waste as fuel in Microbial Fuel Cells (MFCs) (Nastro R.A., Falcucci G., Minutillo M., Trifuoggi M., Guida M., Hodgson, D., Avignone-Rossa C., Dumontet S., Jannelli E., Ulgiati S.) at the Global Cleaner Production & Sustainable Consumption Conference: Accelerating the Transition to Equitable Post Fossil-Carbon Societies, November 2015, Barcelona, Spain. Presentation of poster: "Use of endogenous microflora to obtain electric power from waste-to-bioethanol slurry in Microbial Fuel Cells". (Nastro R., Hodgson, D., Pasquale, V., Dumontet, S. Bushell, M., Avignone-Rossa, C.). 2nd European meeting of the International Society for Microbial Electrochemistry and Technology, September 2014, Alcalá de Henares, Spain.
Start Year 2014
 
Description Pathogen removal 
Organisation Bristol Robotics Laboratory
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Academic/University 
PI Contribution Metagenomic analysis
Collaborator Contribution MFCs for pathogen removal MFCs for chemical removal
Impact Grant proposal submitted Disciplines: Bioelectrochemistry, Nano-bioreactors
Start Year 2016
 
Description Pathogen removal 
Organisation University of Bath
Department Department of Biology and Biochemistry
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Academic/University 
PI Contribution Metagenomic analysis
Collaborator Contribution MFCs for pathogen removal MFCs for chemical removal
Impact Grant proposal submitted Disciplines: Bioelectrochemistry, Nano-bioreactors
Start Year 2016
 
Description Primary School lecture on Production of electricity by microbes (Abingdon, Oxfordshire) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact An experiment was performed by the pupils, where they followed the electrical activity of microbial fuel cells during four weeks, and extracted conclusions in a final lecture.

The pupils asked their teacher if more experiments could be done in the subject. The school has asked if it could be possible to continue with the activity on a regular basis.
Year(s) Of Engagement Activity 2014
 
Description School Experiment 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Thirty year 6 students participated in a week-long experiment to show the activity of microbial communities in diverse natural media (soil, water, plants, etc.).
Year(s) Of Engagement Activity 2016