Enhanced Modification Of The Electroactive Biofilm Of Shewanella Oneidensis MR-1

Electroactive biofilm is a densely conductive population formed by the exopolysaccharide,extracellular protein,extracellular DNA,pili and other polymers secreted by electroactive microorganisms.Biofilms are different from single cells in the form of aggregation and play an important role in microbial electrocatalytic systems.In the natural state,the electroactive biofilm is limited by thin thickness,small cell volume and unstable structure,and the electron transfer efficiency is low.In this paper,on the one hand,the intracellular molecular regulation and extracellular structural components of electroactive microorganisms were modified by the method of synthetic biology;on the other hand,the"artificial biofilm"was constructed by the co-modification and modification of nanomaterials electrodes and electrogenic bacteria cells by non-biological methods.Using the above two aspects,S.oneidensis produced an electroactive biofilm with efficient electron transfer ability,which provided ideas and directions for the further realization of efficient electrocatalysis in the future.The main research results are as follows:1.Engineering modification of Shivella to produce highly electroactive biofilm:Firstly,24 heterologous genes related to biofilm were screened by molecular biology method to obtain 4 optimal genes.Next,the four genes were modular assembled according to their functions,and an engineering bacterium with high power generation capacity was screened:Pyy DT-H3 Further electrochemical and biochemical analysis of the engineered bacteria showed that the maximum voltage of pyydt-H3 was 478.2±9.8m V,and the maximum power density was 535.5±12.3 m W/m~2,which was about 17.8times that of the wild type.2.The"artificial biofilm"was constructed by the co-modification of electrode materials with nanomaterials and modified electrogenic bacteria:firstly,the anode carbon cloth was modified with nanomaterials single-wall carbon nanotubes(SWCNT),and then a layer of SWCNT was modified on the surface of engineering bacteria introduced into pil T gene.In this way,a"3D artificial biofilm"with dense three-dimensional structure was constructed on the surface of MFCs anode under the double modification and modification of SWCNT.The maximum voltage and maximum power density of the electroactive biofilm constructed with the assistance of nanomaterials reached 560±8.7 m V and 179.5±6.2 m W/m~2,about 6 times that of the control group.The results show that the biological modification of microorganisms in the formation of electroactive biofilm can greatly break through the ability of the natural state,non-biological means to make up for the shortcomings of biological means,both of them jointly promote the ability of S.oneidensis electroactive biofilm formation.