Boron-tolerant bacteria in bioremediation: mechanisms, applications, and prospects for environmental sustainability.

Boron (B) is an essential micronutrient with a narrow threshold between deficiency and toxicity, posing significant challenges to environmental and agricultural sustainability. Conventional remediation technologies are often unsustainable due to their high operational costs, high energy demands, and generation of secondary pollutants. In contrast, Boron-tolerant bacteria have emerged as eco-friendly alternatives for bioremediation. Boron-tolerant bacterial strains from genera such as Bacillus, Lysinibacillus, and Microbacterium not only reduce B bioavailability but also enhance plant tolerance when applied in phyto-bioremediation systems. The integration of omics technologies and genetic engineering is accelerating the understanding and optimization of these microbial processes. This review consolidates the current understanding of B occurrence, transport, and toxicity, with a focus on bacterial tolerance mechanisms, including efflux systems, bioaccumulation, quorum sensing, and redox regulation. Molecular-level insights, such as the role of orthologous transport genes (e.g. MFS and RND families), were also evaluated. Additionally, proteomic evidence of B responsive proteins provide functional perspectives. The diversity of boron-tolerant bacteria and their bioremediation potential, particularly within integrated plant-microbe frameworks for sustainable remediation, have been critically evaluated. We also highlight current limitations, knowledge gaps, and future prospects for deploying Boron-tolerant bacteria as a sustainable solution in environmental management, aligning with global sustainability goals.