Iron Reduction Ability And Electricity Generation Ability Of Desulfocurvibacter Isolated From Offshore

Dissimilatory iron-reducing bacteria are microorganisms that can use extracellular insoluble iron minerals as the final electron acceptor to carry out anaerobic metabolism to obtain energy for their own growth and reproduction.This type of metabolism is called iron respiration.Different from the traditional form of breathing,iron respiration represents a new type of metabolism-extracellular respiration.Since the isolation of the first dissimilatory iron-reducing bacteria in 1987,the form of microbes that transport electrons from intracellular metabolized organic matter across the membrane to insoluble electron receptors outside the cell has attracted wide attention.Different dissimilatory iron-reducing bacteria have also been gradually isolated.In this study,the culture obtained by preliminary anaerobic incubation of marine iron corrosion products was used as the original material,and a Desulfocurvibacter with dissimilatory iron reducing ability was further separated and purified.And then,its physiological and biochemical characteristics,dissimilatory iron reduction ability,genetic information profile and electrochemistry were studied.The characteristics are studied in order to obtain strains that have both iron respiration ability and electricity-generating respiration ability.（1）Isolation and purification of the strain and its physiological and biochemical characteristics.Using SRB medium as the selection medium,the original materials were transferred and cultured multiple times to obtain strains that can grow stably in SRB medium.The growth curve showed that the best temperature for strain growth was 37°C,salinity was 14.3‰,and p H was 5.The strain had strong ability to metabolize lactate and formate,can utilize methanol and ethanol,and can use amorphous iron and sulfate as electron acceptors.The results of gram staining indicated that the strain was a gram-negative bacterium.And the results of scanning electron microscopy indicated that the strain was a long rod-shaped bacterium.（2）Complete genome sequence.The strain was cultivated in natural seawater medium,and a certain number of bacteria were collected by centrifugation and sent to the sequencing company for complete genome sequencing.Through comparative genomic analysis,the strain was found to be closely related to Desulfocurvibacter africanus subsp.Africanus,and the strain was named as Desulfocurvibacter sp.YM.Synthesize the genome information to obtain the phylogenetic tree and the complete genome map of the strain based on the complete genome data.（3）Analysis the dissimilatory iron reducing ability of the strain.The strain had different dissimilative reduction abilities to ferric citrate,amorphous iron,and Fe₂O₃,and the reduction rate decreased sequentially.Using Mn O₂ as the electron acceptor,it was found that the strain did not have the ability to reduce dissimilation manganese;the amount of Mn O₂（20 mmol）was added to the same system with amorphous iron,iron citrate,and Fe₂O₃,and it was found that the dissimilation reduction of Fe（Ⅲ）by the strain was affected.Inhibition.The strain had both dissimilation iron reduction ability and sulfate reduction ability.The concentration of sulfate affected the rate of dissimilation reduction of amorphous iron by the strain,and basically had no effect on the dissimilatory reduction of ferric citrate.Taking Shewanella oneidensis MR-4 as a positive control,the ability of this strain to reduce amorphous iron was stronger than that of the positive control strain,and its ability to reduce iron citrate is weaker than that of MR-4.X-ray diffraction analysis was performed on the minerals obtained by dissimilation iron reduction of the strain,and no iron minerals with crystal forms were found obviously.（4）Electrochemical characteristics of the strain.Construct a dual-chamber microbial fuel cell to study the power generation capacity of the strain.The growth status of strains was closely related to the ability to produce electricity.Transferring vigorous strains to the fuel cell had a shorter battery startup time;when the concentration of the substrate in the battery was higher,the ability to produce electricity was stronger;the initial transfer bacterial solution volume was larger,the earlier the battery output current.