The Survival Time Elongation Of Pseudomonas Aeruginousa CAN Improve The Output Power In Microbial Fuel Cells

Microbial fuel cells(Microbial Fuel Cells,MFCs)is the system using microorganisms to transfer the chemical energy in the organic matter directly into the electrical energy,which can remove pollutants and produce electricity simultaneously.Pseudomonas aeruginosa can produce electron transfer compounds phenazine and can be applied into the construction of MFCs.How to improve electron producing properties of MFCs is the research hot point.In this study,the MFCs based on P.aeruginosa SJTD-1 and its mutant strain was constructed and the factors influencing the discharge process were studied.Results showed that the secondary metabolites,phenazine-1-acid(PCA)produced by P.aeruginosa SJTD-1,is the main electron transfer chemical in MFC,the voltage generated by MFC increased with its concentration up.Despite the PCA yield of the knockout mutant strain SJTD-1(? mvaT)higher than that of the wild type strain SJTD-1,the maximum discharge voltage of its MFC was only 130 mV,much lower than the 440 mV of wild type.However,the voltage curve of two MFCs were quite different.The MFC of mutant strain can keep the highest peak voltage for approximately 40 hours,while the voltage of the wild type strain decreased rapidly after reaching its peak value.These results indicated that PCA was the main factor for the discharge process in MFCs,but not the only factor.Further studies showed that the number of survival cell in the fermentation broth of MFC will affect its electricity yield.In the initial phase,the discharge voltage generation in MFCs increased with the number of live bacteria growing up.When the maximum number of live bacteria reached,the voltage of MFC was at the peak.And when the number of live bacteria decreased,the voltage also went down.Comparing with the wild-type strain,mutant strain SJTD-1(? mvaT)can survive much loger time in the fermentation process and its discharge time was more durable.MFC of the wild type SJTD-1 can only discharge 90 hours,and its total power was 1.30 J.Mutant strain SJTD-1(? mvaT)can continuously discharge more than 160 hours in MFC,and produce 2.32 J of the total power.Therefore,extension the cell survival time in MFC system can improve its discharge time and the total power output.Furthermore,to explore the possible mechanism of extended cell survival time,we use i-TRAQ based proteomics analysis to compare the protein expression levels in the wild strain SJTD-1 and mutant strain SJTD-1(? mvaT)in minimal medium.Results showed that the expression levels of 66 proteins showed significant differences,including 37 up-regulated proteins and 29 down-regulated proteins.These proteins are involved in cell transportation and metabolism,cell defense,signal transduction and etc.The expression levels of several genes related to cell growth increased,such as opmD gene,whose expression level in mutant strains was 4.9 times higher than that in wild type strain,may related to the prolonged survival time.This work can provide a new idea for the power improvement research and help to promote its practical application.