Molecular Soil Biology 2025, Vol.16, No.1, 16-26 http://bioscipublisher.com/index.php/msb 17 This systematic review and perspective paper aims to provide a comprehensive overview of the mechanisms by which synthetic microbial communities can be tailored for the bioremediation of saline-alkali soils. By synthesizing current research findings, this paper will highlight the potential of SynComs to mitigate soil salinization and improve agricultural productivity. The review will also discuss field applications and the practical challenges associated with implementing SynCom-based bioremediation strategies. The significance of this paper lies in its potential to inform future research and guide the development of effective, sustainable solutions for managing saline-alkali soils, thereby contributing to global food security and environmental sustainability. 1 Understanding Saline-Alkali Soils 1.1 Characteristics and formation of saline-alkali soils Saline-alkali soils are characterized by high concentrations of soluble salts and exchangeable sodium, which adversely affect soil structure and fertility. These soils typically exhibit poor physical properties, such as low permeability and high pH levels, which hinder plant growth and microbial activity. For instance, in the Yellow River Delta, China, saline-alkali soils have been found to possess a porosity ranging from 19.55% to 34.90%, with a significant presence of micropores and ultra-micropores, contributing to their poor permeability (Li et al., 2021). The formation of these soils is often attributed to natural processes such as the evaporation of saline groundwater and the deposition of salts from marine or lacustrine sources, as well as anthropogenic activities like improper irrigation practices. 1.2 Environmental and agricultural challenges posed by saline-alkali soils Saline-alkali soils pose significant environmental and agricultural challenges. They limit the availability of essential nutrients and water to plants, leading to reduced agricultural productivity. Additionally, these soils contribute to increased greenhouse gas emissions, as evidenced by a study in the Hetao Irrigation District of Inner Mongolia, which found that high saline-alkali soils significantly increased the Global Warming Potential (GWP) due to altered methane (CH4) uptake and nitrous oxide (N2O) emissions (Yang et al., 2018). The cumulative uptake of CH4 was reduced by up to 28%, while N2O emissions increased by up to 45% in high saline-alkali soils compared to low saline-alkali soils (Yang et al., 2018). These environmental impacts underscore the need for effective remediation strategies. 1.3 Traditional methods of remediation and their limitations Traditional methods for remediating saline-alkali soils include physical, chemical, and biological approaches. Physical methods such as leaching and drainage aim to remove excess salts from the soil profile but are often limited by water availability and infrastructure costs. Chemical amendments, including gypsum and other soil conditioners, can improve soil structure and reduce sodium levels but may not be sustainable in the long term. For example, the application of biochar and soil modifiers has been shown to significantly increase soil organic carbon (SOC) content and improve soil fertility in China (Yang et al., 2022). However, these methods may not address the underlying causes of soil salinization and alkalization. Biological approaches, such as planting halophytes and using microbial inoculants, offer more sustainable solutions but require further research to optimize their effectiveness and scalability. 2 Synthetic Microbial Communities (SynComs) 2.1 Definition and principles of SynComs Synthetic Microbial Communities (SynComs) are artificially designed consortia of microorganisms that are engineered to perform specific functions, such as bioremediation of contaminated environments. Unlike natural microbial communities, which evolve through natural selection and environmental pressures, SynComs are constructed using principles of synthetic biology and systems biology to achieve desired outcomes with greater precision and efficiency (Sharma and Shukla, 2020). These communities are designed by selecting and combining microbial strains with complementary metabolic capabilities, enabling them to degrade a wide range of pollutants simultaneously (Sharma and Shukla, 2020; Wang et al., 2023).
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