Study On Heavy Metal Adsorption Characteristics And Mechanism Of Endophyte Staphylococcus Succinus H3

Heavy metal pollution is recognized as a serious environmental pollution problem that is serious and difficult to govern.Since heavy metals have high toxicity and non-degradability,they enter the human body to form a stable biomotropic compound,thereby disrupting normal physiological activities,leading to functional damage such as liver and kidney,and also induces cancer.Microbial structural macromolecules and their metabolites are rich in carboxy,amines,hydroxyl groups,phosphorus and mercapto groups,can have higher binding capabilities with metal ions,and can reach the adsorption of heavy metal ions by mediating metal cationic reducing properties.Includes extracellular adsorption and intracellular accumulation.At present,research based on microorganisms is in the ascendant,including some microbial strains,including fungi and bacteria,found ideal heavy metal enrichment capabilities,which laid the foundation for the development of cheap environmentally friendly repair materials.S.succinus H3 is one of the 12 strains of electroproducing bacteria isolated from Angelica sinensis by our research group.We systematically explored its electroproducing capacity,methyl orange degradation and Cu²⁺adsorption.It was found that S.succinus H3 had good properties of electricity generation,methyl orange degradation and Cu²⁺adsorption.Based on the adsorption characteristics of Cu²⁺by S.succinus H3,this study systematically characterized the tolerance and adsorption performance of S.succinus H3 to 10 common metal ions,and adopted response surface optimization for the influencing factors of S.succinus H3 adsorption of heavy metal ions.The adsorption mechanism of S.succinus H3 was investigated through kinetic model and chemical characterization.The main conclusions are as follows:1.Study on heavy metal tolerance and adsorption characteristics of S.succinus H3Morphological observation and growth amount measurement showed that S.succinus H3 had a good tolerance to different concentrations of metal ions,and its biomass decreased with the increase of metal ion concentration.Under the lethal concentration,the cell wall membrane of S.succinus H3 cell formed holes and cell contents leaked,resulting in cell death.When Mg²⁺concentration is 9 m M,it can promote the growth of S.succinus H3.In a single metal ion system,S.succinus H3（live strain,dead strain）has adsorption properties for metal ions(Cd²⁺,Cu²⁺,Mg²⁺and Pb²⁺),and its adsorption capacity is positively correlated with metal ion concentration.In the mixed ion system,the adsorption capacity and affinity of living S.succinus H3 strain to metal ions were better than those of dead strain.2.Optimization of heavy metal adsorption capacity of S.Succinus H3Box-behnken model was used to determine the optimum adsorption conditions of S.succinus H3 for Cu²⁺ions on the basis of orthogonal tests with 5 factors and 3 levels.The results show that the fitting degree of the model is ideal.The interaction of ion concentration,time,biomass,temperature and PH on the adsorption rate was significant.The optimal adsorption conditions were predicted and verified by Design-Expert V10.0:11.525 h,246.122 mg/L,196.358 mg,10.951℃,9.662,and the maximum adsorption rate reached 87.962%.3.Kinetic simulation of heavy metal adsorption by S.succinus H3The kinetic and isothermal models show that the adsorption process of Cu²⁺by S.succinus H3 conforms to the quasi-second-order kinetics.This process is heterogeneous surface adsorption.Besides surface adsorption,intracellular accumulation can also be carried out.Similarly,the adsorption process of S.succinus H3 on Cr⁶⁺also conforms to quasi-second-order kinetics,and the metal ions are complexed by the action of bacterial surface functional groups/electrostatic attraction coordination.Langmuir isothermal model has a high fitting correlation,and the adsorption process may be uniform monolayer adsorption.4.Study on the adsorption mechanism of heavy metals in S.succinus H3Based on scanning electron microscopy（SEM-EDS）,Fourier Transform infrared spectroscopy（FT-IR）,X-ray diffraction（XRD）and X-ray photoelectron spectroscopy（XPS）,it was found that the morphology of S.succinus H3 changed in different degrees after the adsorption of Cd²⁺,Cu²⁺and Mg²⁺.The bacteria grew well in Mg²⁺environment,and C,O,N,Cd,Cu and Mg elements were distributed in vitro and in vivo.N-h group,protein C=O group,polysaccharide C-O group,O-H group and some lipids are the main functional groups in cell wall.The adsorption process can lead to the rearrangement of macromolecular substances or the formation of amorphous substances in cells.S.succinus H3 can bond with amine group to adsorb Mg²⁺through complexation/coordination,and copper complex may be formed after adsorbing Cu²⁺.In conclusion,S.succinus H3 has a strong tolerance and adsorption ability to a variety of metal ions,and optimization of adsorption conditions can significantly improve the adsorption efficiency of strain,and preliminarily explore the adsorption mechanism of S.succinus H3 to heavy metal ions.The results of this study can provide an expanded resource base and theoretical basis for the application of microbial adsorption of heavy metals.