Research Progresses and Prospects on the Application of Magnetotactic Bacteria in Environmental Remediation
s:Magnetotactic bacteria(MTB)are microorganisms capable of synthesizing intracellular magnetic nanoparticles,termed magnetosomes,through biomineralization.These bacteria are widely distributed across various natural environments,including lakes,marine ecosystems,wetlands,soil,and sediments,and they utilize magnetosomes for directional movement.Magnetosomes,primarily composed of magnetite(Fe₃O₄)or greigite(Fe₃S₄),exhibit exceptional biocompatibility and superparamagnetic properties.Due to these unique characteristics,MTB holds significant promise for applications in medicine,biology,geology,and environmental remediation.This review introduces the distribution and characteristics of MTB,highlights the main devices and methods used for enriching and screening MTB in the natural environment,and discusses the development of culture conditions for MTB.Furthermore,it examines the recent research progress in the application of MTB to remediate polluted environments.Studies have revealed that MTB can efficiently remove heavy metals from wastewater,including gold,chromium,cadmium,silver,and copper.The mechanism of heavy metal removal by MTB is dominated by ion exchange processes,including physical adsorption,chemical complexation,and intracellular accumulation.Functional groups such as hydroxyl,amide I,and carboxyl groups are involved in the adsorption of cadmium by MTB.In addition to heavy metals,MTB plays a role in the removal of organic pollutants,radionuclides,toxic salts,and pathogens from various environments through physical adsorption and chemical reduction.Additionally,this review reveals the techniques and devices for recovering MTB from polluted water after remediation.The recovery principle leverages magnetic fields to guide the MTB to swim directionally,causing it to accumulate near the magnetic poles for separation and recovery.Although MTB has shown emerging potential in wastewater treatment,several challenges hinder its widespread application in pollution remediation.First,despite the widespread presence of MTB in natural environments,only a few species have been successfully cultured.Identifying and purifying MTB from natural environments is critical for its application in environmental pollution remediation.Second,aside from the small number of model strains,optimizing MTB growth and magnetosome production conditions for most MTB strains remains challenging,making large-scale cultivation difficult.Third,current recovery devices for MTB are primarily suited to aquatic environments,whereas effective separation and recovery systems for MTB in sediments and soils are yet to be designed and developed.In the future,the integration of advanced screening techniques such as single-cell and high-throughput screening will facilitate the identification and isolation of culturable MTB strains from diverse natural environments.Subsequently,optimizing the culture conditions for these isolated strains and enhancing magnetosome production will be essential for achieving high bacterial biomass and magnetosome yields.Innovative devices that enable MTB to adsorb a wide range of pollutants,particularly heavy metals,in water,soil,and sediment environments have been developed.These devices must also incorporate magnetic separation and recovery systems under magnetic-field conditions to achieve effective pollution reduction and environmental remediation.Finally,comprehensive research is required to clarify the mechanisms and influencing factors underlying adsorption and pollutant removal by MTB.These investigations provide valuable insights and novel methodologies to advance MTB-based pollution remediation technologies.
magnetotactic bacteriamagnetosomesenvironmental pollution remediationheavy metal removalmagnetic recycling
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