The Regulation Of Anode Community Promotes The Production Capacity Of Microbial Fuel Cells

Microbial fuel cells(MFCs)are a new energy technology,which are widely used in energy and water treatment fields.The low power output is still the major barrier for large-scale industrial applications,and the slow interfacial electron transfer rate from bacteria to anode is one of the main bottlenecks.To overcome this problem,great efforts have been made to develop efficient anode bacteria group.MFC can generate current during operation,but due to the difference in anode organic matter content and bacterial source,the power output is also different.Generally speaking,the output power of MFC in the initial operation is low.Through the screening of sediments and enrichment in multiple operations,the construction of efficient MFC can effectively increase the output power of MFC and enrich the anode flora.Running the MFC multiple times can practically enrich the electricigens,and thus improve its power generation efficiency.However,Gram-positive electricigens cannot be enriched well because of their thick non-conductive peptidoglycan layer.Herein,we report a new Gram-positive electricigen enrichment method by regulating the peptidoglycan layer of the bacteria using lysozyme.The study found that the trend of electricity generation performance of sediment fuel cells constructed with different sources of deposits with and without added carbon sources is consistent,and the addition of carbon sources has no obvious effect on the productivity of sediment microbial fuel cells.The original organic matter content of the sediment has a great influence on the capacity of the sediment fuel cell.When the sediment is taken from the Licheng sewage treatment plant in Jinan,the organic content is the highest(7.37%)and the highest voltage(539 m V)is generated.Therefore,the sediments of Licheng Sewage Treatment Plant were selected and enriched in multiple rounds of operation to further construct efficient sediment fuel cells.As the battery operating cycle increases,the output voltage of the battery stabilizes at 660±5 m V in the fourth round,and the enrichment optimization is completed.The analysis and comparison of the structure of the enriched community of the high-efficiency sediment fuel cell and the original sediment community showed that the proportion of electro-producing bacteria(Bacteroidetes and Proteobacteria)of the anode community after multiple rounds of enrichment increased by 31.57%.Non-electrogenic bacteria such as Lentimicrobiaceae have been eliminated or even disappeared.As a result,an efficient sediment fuel cell and an enriched bacterialcommunity conducive to productivity are obtained.Further research found that,through multiple rounds of electrochemical operation of high-efficiency sediment fuel cells,most of the gram-negative electro-producing bacteria were enriched.However,due to their thick non-conductive peptidoglycan layers make them difficult to be enriched.Therefore,in this study,the use of lysozyme to regulate the peptidoglycan layer of bacteria did not affect the abundance of Gram-negative electro-producing bacteria while enriching Gram-positive electro-producing bacteria.Increase the proportion of total electro-producing bacteria in the community and the overall performance of MFC.After lysozyme regulation,the peptidoglycan content of the bacteria group was reduced by 26.67%,which increased the permeability of the cell wall of Gram-positive bacteria,thereby enhancing its electrical activity.Gram-positive electrogenic bacteria(Firmicutes)are abundantly enriched,and the abundance increases from 2.84% to 14.87%,increasing the proportion of total electricity-producing bacteria from 80.33% to 90.47%,which constitutes the MFCs high-electricity-producing community structure.The power density of MFC is 42% higher than the control sample.Therefore,our research provides a new and simple method to optimize the structure of the anode flora by regulating the weak electricity-producing bacteria in the community with lysozyme.In this paper,through a new method of regulating the microbial fuel cell anode flora,the abundance of Gram-positive electricity-producing bacteria is increased without affecting the enriched Gram-negative electricity-producing bacteria,and the flora is further improved.The proportion of total electricity-producing bacteria in the medium has improved the electricity-generating performance of microbial fuel cells.The microbial fuel cell is an interdisciplinary field,and it is still in the laboratory stage.This study provides a new idea and method for regulating the anode flora and improving the productivity of microbial fuel cells,which will also contribute to the further promotion and application of this technology.