Exploitation Of Electric Bacteria Resources In Plants And Study On Their Electricity Production Performance

Microbial fuel cell?MFC?is widely studying as an emerging technology for pollution treatment and energy supply.The distribution of electricity-producing microorganisms'resource is one of the current research hotspots.A large number of electricity-producing microorganisms are concentrated and isolated from various environments such as sewage,soil,and bottom sediments at present.However,many resources of electricity-generating microbial have not been excavated widely,such as plant endophyte resources.Abundant resources will bring more discoveries to the mechanism and application research of electricity-generating microorganisms.This study starts with the excavation of electricity-producing microbial resources and excavates the rich endophytic resources of plants.In the experiment,WO₃ nanoprobe was used to isolate and identify electricity-producing endophytes of plants.All of these strains and plant tissue were inoculated in MFC,and the electrochemical performance was analyzed by collecting voltage curves,power density curves,cyclic voltammetry curves,and scanning electron microscope?SEM?of anode electrode membranes.At the same time,a high-throughput analysis was performed on the MFC anode microbial community of plant tissues.The application of the excellent power-producing strains in methyl orange degradation and Cu²⁺adsorption was also explored.The study has proved the feasibility of plant endophytes as a source of electricity-producing microbial resources and has found its potential for application in environmental protection.The main research results are as follows:1.In the experiments,The electricity production of endophytic bacteria and fungi of Ipomoea batatas?L.?Lam.,Angelica sinensis,Solanum tuberosum,DioscoreaoppositaThunb.,Nelumbo nucifera Gaertn and Daucus carota L.var.sativa Hoffm.were detected via WO₃ nanoprobe.Seventeen electric-producing endophytes were isolated from the tubers of Angelica sinensis and Ipomoea batatas?L.?Lam.,6 of them were identified,D1 was Bacillus zhangzhouensis;D2 was Pleomorphomonas oryzae;D4was Rahnella aquatilis;H1 was Paenibacillus cucumis;H3 was Staphylococcus succinus subsp.Succinus;H11 was Shinella zoogloeoides,respectively.Preliminary verification of plant endophytes has electrochemical activity.2.The results of high-throughput analysis of the microbial community structure of MFC and anodic membrane inoculated with Ipomoea batatas?L.?Lam.and angelica sinensis showed that the microorganisms'structure of MFC inoculated was different from that of MFC in other environments.In the anolyte and anodic biofilm inoculated with Angelica sinensis were mainly concentrated in Proteobacteria.The Firmicutes in the anolyte of MFC inoculated by Ipomoea batatas?L.?Lam.occupies an absolute advantage,while the dominant population of anodic biofilm is Proteobacteria.At the genus level,Pseudomonas was the dominant bacterium in the anolyte in the MFC inoculated with Angelica sinensis.The dominant species in the anode electrode samples are Clostridioides and Pseudomonas.Staphylococcus and Lachnoclostridium 5 in Ipomoea batatas?L.?Lam.inoculated MFC are dominant bacteria in both anolyte and anode electrode.3.Six isolated strains of electric-producing bacteria were tested for electrochemical activity.MFC inoculated with a single strain of electric-producing bacteria in the plants all showed a certain ability to produce electricity.The power density curve shows that the maximum power density that strains D1,D2,D4,H1,H3,and H11 can produce reach24.9±1.7 mW/m²,38.5±4.3 mW/m²,24.4±3.0 mW/m²,51.9±2.5 mW/m²,122.9±3.5 mW/m² and 78.3±1.8 mW/m².Cyclic voltammetry and SEM observations of anode carbon felt showed that D1,D2,H1,H3,and H11 may have multiple direct and indirect electron transfer methods,D4 may transfer electrons through direct contact,and H3 is similar to nanowires.Electrochemical activity tests performed on Angelica sinensis and Ipomoea batatas?L.?Lam.inoculated MFC showed power densities of 196.9±5.8mW/m² and 142.9±16.4 mW/m²,respectively.4.Application research on methyl orange degradation of the selected electric-producing bacteria H3and the resultsfound that H3 can tolerate a pH range of 5-10 and can tolerate a NaCl concentration of 23%.Under normal conditions,it can degrade 20 mg/L methyl orange within 36 h.The suitable decoloring temperature is 25-45°C,pH is 5-8,NaCl concentration is 1-7%,Fe³⁺,Fe²⁺,Cu²⁺and oxygen can inhibit the degradation of methyl orange by H3.5.The application research of Cu²⁺adsorption on H3 found that the adsorption capacity of Cu²⁺on H3 could reach 14.3 mg/g after the adsorption reaches equilibrium under normal conditions.The suitable adsorption temperature of H3 is 25-45°C,the pH is 6-10,and it still has an adsorption capacity of 10.0 mg/g in a Cu²⁺concentration of50 mg/L.Studies have shown that the production of electrobacterium H3 in plants has certain application potential.