Abstract:

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.

Key words: magnetotactic bacteria, magnetosomes, environmental pollution remediation, heavy metal removal, magnetic recycling

摘要：

趋磁细菌是一类能通过生物矿化在细胞内形成磁性纳米颗粒——磁小体的微生物，广泛分布于多种自然环境中。趋磁细菌利用体内的磁小体进行定向运动。磁小体主要由磁铁矿（Fe₃O₄）或胶黄铁矿（Fe₃S₄）构成，具有独特的生物相容性和超顺磁性。趋磁细菌在医学、生物学、地质学和环境污染治理与修复领域都具有显著的应用潜力。该文首先介绍了趋磁细菌的分布及其特性，其次归纳了从自然界样品中富集趋磁细菌的主要方法和装置并概述趋磁细菌的培养方法，总结国内外趋磁细菌在环境污染治理与修复领域，尤其是在重金属修复领域的研究进展。现有的研究证明，趋磁细菌能有效去除废水中的金、铬、镉、铜等重金属离子，且对环境中的部分有机污染物也具有一定的去除效果。同时，该文也提出目前趋磁细菌的应用遇到的问题和挑战。趋磁细菌的高密度培养难度大、分离回收设备不完善以及应用场景局限，这些因素都限制了趋磁细菌在环境污染治理与修复领域中的应用。最后展望了趋磁细菌在环境修复领域的应用研究应聚焦于优化培养条件以实现大量培养，并研发基于趋磁细菌的修复功能菌剂与技术，为环境中各种污染物尤其是重金属的减量修复提供新方案。

关键词: 趋磁细菌, 磁小体, 环境污染修复, 重金属, 磁性回收