South China Agricultural University, Canton, China Electr ctricit icity Col oli Enables M or ore F res esh h wa water er & & C lea ean n en ener ergy gy wi with th MFC FC Winnie Christ Ziyan Phoebe
Energy crisis Pollutant New energy Clean Renewable Low-cost Non-renewable Energy resources
The “ water planet” is short of fresh water 70% Earth surface water 3% Fresh water 97% Sea water 0.007% Used directly Oceans Ice layer
Sea water desalination based on Electrodialysis Sea water Cathode Anode - + Problem: + High energy + - consumption + - -
Introduction of MFC and MDC Microbial Fuel Cells Microbial Desalination Cells MDCs = MFCs + disalination chamber + e - e - + - O 2 - + PEM PEM AEM CEM Fresh H 2 O PEM - + H + water + - + - Anode Anode Anode Anode Cathode Cathode Cathode Cathode Chamber Chamber Chamber Chamber Chamber Chamber Chamber Chamber Low power output restrains the wide usage of MFC/MDC! PEM: proton exchange membrane AEM: anion exchange membrane; CEM: cation exchange membrane
Des esigns ns and nd Re Results lts of of ou our pr r proj oject ect
Production of electron carrier NADH in cells e - NAD synthetase NaAD NAD + NADH (Electron carrier) Anaerobic Aerobic ArcB Pi ArcA -P TCA TCA ArcA NADH NADH
Two strategies to increase NADH in our project Over-expression Strong nadE e - e - e - e - e - e - NAD + NADH NAD synthetase NaAD NAD + NADH NADH NADH NAD + NAD + Anaerobic (in MFC/MDC) ArcB Pi TCA TCA ArcA ArcA-P ArcA-P Knock-out NADH NADH
arcA gene is knocked-out by λ -Red recombination
Construct for nadE over-expression Xba I - Spe I 2953 bp 2755 bp 2068 bp 875 bp 897 bp
The nadE is over-expressed driven by different promoters S W W S mRNA level Protein level S: Strong Promoter W: Weak Promoter
Our MFC device Anode Cathode chamber chamber Proton exchange membrane (PEM)
The arcA knock-out strain produces more electric change
The nadE over-expression strain produces higher voltage R =10 kΩ
Genetically modified strains produce more electric charge R =10 kΩ Strong Weak
Comparison of electrodialysis and MDCs Electrodialysis Microbial Desalination Cells - + e - - + PEM AEM CEM + - - AEM Fresh CEM - + + Fresh water - - + + water - - + - + Anode Cathode Desalination Chamber Chamber Chamber
Our MDCs device Desalination chamber C Anode chamber Cathode Diluant chamber effluent Concentrate effluent Four-chamber air-cathode MDCs C D D Flow of dilute (D) and concentrate (C) water in MDCs Schematic design of stacks in MDCs
Promising desalination rate is achieved in our MDCs
Con onclusio clusion Eight biobricks were submitted to iGEM database Genetic modification of microbes is a promising way to improve electricity yield Our MFC-based MDC system is able to turn seawater to fresh water Electri ctricit city Coli li
Fut uture ure di direction ection If organic wastewater can be used as energy source by microbes in MFC/MDC, our project will further benefit the environment. If the arcA is controlled by an inducible promoter, the ΔarcA mutant would be rescued under low nutrient condition. Carbon Inducer Starvation Inducible Promoter TCA ArcA-P ArcA-P TCA Knock-out NADH NADH
Human Practice Internet Exhibition Teach-In Public Platform Online Expert Visiting Meet-up Interview Survey
Scientific Exhibition in Guangdong Science Center Exhibition • Exhibition Broad • Microscope Area • Photo Model • Signature wall
High School Teach-In Teach-In • Lectures • Discussions on synthetic biology
Internet Internet Public Platform Public Platform
Expert • MFCs/ MDCs research status Interview • Bi-Language (Chinese and English) Online • Public Awareness Survey
Visiting • Talks with desalination companies • Ideas and Thoughts exchanging Meet-up
All the way down to Boston…… Beijing Guangzhou San Francisco Boston
Te Team Members bers
Te Team Members bers Dry Lab
Acknowledgements Prof. Chen Prof. Deng Prof. Wen Dr. Hu Prof. Hao
Thank you for attention !
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