Antibiotics | Mangrove Ecosystems as Reservoirs of Antibiotic Resistance Genes

This literature systematically reviews the distribution characteristics, environmental driving factors, and horizontal gene transfer potential of antibiotic resistance genes (ARGs) in mangrove ecosystems, providing a new perspective for understanding the spread mechanisms of resistance genes in natural environments.

 

Literature Overview
The paper, "Mangrove Ecosystems as Reservoirs of Antibiotic Resistance Genes: A Narrative Review", published in the journal "Antibiotics", reviews and summarizes the distribution, diversity, and associations of antibiotic resistance genes (ARGs) in mangrove ecosystems with environmental factors and human activities. The literature highlights that mangroves serve both as reservoirs of resistance genes and as natural buffers; however, the risk of resistance gene dissemination is significantly influenced by human activities such as aquaculture and urban wastewater inputs.

Background Knowledge
Antibiotic resistance genes (ARGs) are widely present in the environment and represent one of the major global public health and ecological safety challenges. In recent years, the development of high-throughput sequencing technologies has provided new approaches for environmental genomics to trace the sources, transmission pathways, and interactions of ARGs with microbial communities. Due to their unique sedimentary environments and microbial diversity, mangrove ecosystems have become important natural models for studying the dynamic changes of ARGs. Previous studies have indicated that the distribution of ARGs in mangroves is closely related to land use, water pollution, and microbial community structures, but a systematic review has been lacking. This study fills that gap by analyzing the ecological function of mangroves as reservoirs of resistance genes and their potential dissemination risks, which holds significant value for environmental and public health research.

 

 

Research Methods and Experiments
The research team conducted a systematic literature search across databases including PubMed, Scopus, and Web of Science, selecting 17 primary studies published between 2008 and September 2024, covering mangrove areas in Southeast Asia, South Asia, South America, and Africa. Sample types included sediment (80%), water (50%), and symbiotic organisms (e.g., shrimp, crabs, mollusks). Detection methods included qPCR, 16S rRNA sequencing, and metagenomic sequencing, with data extraction covering ARG types, microbial community structures, environmental factors, and pollution sources. The study employed narrative synthesis without quantitative aggregation to reflect heterogeneity among the selected studies.

Key Conclusions and Perspectives

• Tetracycline (tetA, tetM), sulfonamide (sul1, sul2), beta-lactam (bla_TEM, bla_CTX-M), and multidrug resistance genes (mdt, acr) are widely detected in mangrove ecosystems.
• ARG abundance ranges from 10² to 10⁶ copies per gram in sediment and 10² to 10⁴ copies per milliliter in water, significantly influenced by aquaculture and urban wastewater inputs.
• Metagenomic studies reveal that Proteobacteria, Firmicutes, and Bacteroidetes are the dominant microbial phyla carrying resistance genes in mangroves, with strong correlations to opportunistic pathogens such as Vibrio, Pseudomonas, and Enterococcus.
• Mobile genetic elements (MGEs), such as plasmids, transposons, and gene cassettes, frequently co-occur in mangrove sediments, indicating a high risk of horizontal gene transfer.
• Seasonal variations and sediment properties (e.g., organic matter, salinity, particle size) significantly affect the distribution and abundance of ARGs; abundance generally increases during rainy seasons and decreases in areas distant from pollution sources.
• Although mangroves possess natural filtration and competitive microbial inhibition functions, intensive human activities can overwhelm their natural buffering capacity, leading to continuous ARG dissemination.

Research Significance and Prospects
This study emphasizes the dual role of mangroves in the ecological spread of antibiotic resistance genes: as reservoirs and as potential dissemination nodes. Future research should standardize ARG detection methods, expand to underexplored mangrove regions globally, evaluate the potential of mangrove restoration in mitigating ARGs, and integrate metagenomics with functional experiments to decipher the ecological impact of resistance genes. Additionally, the study advocates for a One Health approach that integrates environmental, public health, and policy-making perspectives to control the spread of resistance genes.

 

 

Conclusion
Mangrove ecosystems, while maintaining coastal ecological balance, also serve as significant environmental reservoirs of antibiotic resistance genes (ARGs). Literature shows that human activities, such as aquaculture and urban wastewater discharge, significantly promote ARG accumulation, whereas natural environmental factors like sediment organic matter, salinity, and microbial community structures influence their dissemination dynamics. The presence of mobile genetic elements further enhances the risk of horizontal gene transfer among microorganisms. Although mangroves possess some natural buffering capacity, their ability to suppress ARGs is compromised under intense pollution pressure. Therefore, key strategies to curb ARG dissemination include reducing antibiotic misuse, strengthening environmental monitoring, protecting and restoring mangrove ecosystems, and fostering interdisciplinary collaboration.

 

Monthon Lertcanawanichakul, Phuangthip Bhoopong, and Phusit Horpet. Mangrove Ecosystems as Reservoirs of Antibiotic Resistance Genes: A Narrative Review. Antibiotics.