Global study maps how bacterial communities shape the health of lakes and reservoirs
Maximum Academic Press
Their findings show that sediments contain consistently higher and more variable bacterial diversity than surface waters, while global patterns are strongly shaped by temperature, nutrient levels, and latitude. By establishing a standardized worldwide microbial database, the team identifies key bacterial groups—such as Proteobacteria, Cyanobacteria, and Actinobacteria—that indicate ecological conditions and nutrient status.
Lakes and reservoirs provide drinking water, support biodiversity, and sustain agriculture and industry, yet face mounting stress from pollution, nutrient enrichment, and climate-driven hydrological changes. Microorganisms play central roles in these ecosystems by regulating carbon, nitrogen, and phosphorus cycling, underpinning food webs, and maintaining resilience against disturbances. Because microbial communities respond sensitively to temperature, oxygen, pH, and nutrient dynamics, shifts in bacterial composition act as early-warning signals of eutrophication or ecological degradation. Despite growing interest, global comparisons linking microbial biogeography to environmental gradients in both water and sediment habitats have remained limited. Addressing this knowledge gap is essential for building predictive models of ecosystem change.
A study (DOI:10.48130/biocontam-0025-0003) published in Biocontaminant on 31 October 2025 by Haihan Zhang’s team, Xi'an University of Architecture and Technology, offers new scientific foundations for microbial-based water-quality monitoring and sustainable freshwater ecosystem management.
In this study, the researchers synthesized 379 publicly available amplicon-sequencing datasets from water and sediment samples and applied a suite of analytical methods—including continental grouping, latitude-based gradients, diversity indices, Spearman correlations, Generalized Additive Models (GAM), Structural Equation Modeling (SEM), Random Forest analysis, redundancy analysis (RDA), and ecological network construction—to investigate global patterns in bacterial biogeography. This integrative methodological framework enabled the team to overcome uneven sampling across continents, capture nonlinear environmental responses, identify key predictors of community structure, and compare interaction networks between habitats. The resulting analyses revealed that although the dataset covers six continents, more than 60% of samples originated from Asia, creating a geographical imbalance that was mitigated by regional grouping and incorporation of latitude. Diversity assessments showed consistently higher Shannon and Chao1 indices in sediments than in water, with sediment samples—especially those from Asia—displaying far greater richness and variability. GAM and SEM analyses uncovered strong nonlinear environmental effects: in water, bacterial richness peaked around 7 mg/L dissolved oxygen and declined sharply above 25 °C, while diversity decreased steeply at latitudes above 60°. Nutrient effects differed between habitats, with total nitrogen and nitrate enhancing diversity in sediments but suppressing it in water. Taxonomic analyses identified Proteobacteria as globally dominant, while Cyanobacteria and Actinobacteria proliferated in eutrophic waters; other phyla exhibited distinct habitat-specific preferences. Random forest models highlighted temperature as the leading driver of water-column community structure, whereas nitrate nitrogen was most influential in sediments. RDA further confirmed strong environmental shaping of water communities, while sediment communities exhibited more moderate associations. Network analyses showed striking habitat contrasts: water communities formed dense, highly connected networks indicative of rapid interactions and dynamic environmental fluctuations, whereas sediment networks were sparser and more modular, reflecting niche specialization and geochemical filtering. Collectively, these results demonstrate that habitat type, environmental gradients, and regional context jointly regulate bacterial diversity, composition, and ecological interactions across global lakes and reservoirs.
These global biogeographic insights strengthen the scientific basis for microbial indicators in freshwater monitoring. Identifying core bacterial groups associated with nutrient levels, temperature, and geographic position provides powerful tools for early detection of eutrophication, pollution events, and ecological recovery. The global database and statistical models developed in this study offer practical guidance for water-resource managers aiming to predict ecosystem responses to nutrient loading, climate warming, and land-use change.
###
References
DOI
Original Source URL
https://doi.org/10.48130/biocontam-0025-0003
Funding information
This study was funded by the Shaanxi Outstanding Youth Science Foundation Project (Grant No. 2025JC-JCQN-019), supported by the Postdoctoral Fellowship Program of CPSF (Grant No. GZC20250855), and the National Natural Science Foundation of China (Grant Nos 52270168, 52570213, and 52500012).
About Biocontaminant
Biocontaminant is a multidisciplinary platform dedicated to advancing fundamental and applied research on biological contaminants across diverse environments and systems. The journal serves as an innovative, efficient, and professional forum for global researchers to disseminate findings in this rapidly evolving field.
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Exploring bacteria communities in lakes and reservoirs: a global perspective
Environmental traces of antibiotics found to boost gene transfer among bacteria
Maximum Academic Press
Using models of vertical inheritance and horizontal transfer, they found that low doses of tetracycline, ampicillin, kanamycin, and streptomycin stabilize resistance and promote gene transfer across species. Mechanistic analyses reveal increased oxidative stress, membrane permeability, and ATP production as drivers, while modeling predicts that long-term exposure to such low-level antibiotics leads to faster and more persistent expansion of resistant bacteria.
Antibiotic resistance is a major global health threat, contributing to an estimated 1.27 million deaths annually and projected to cause 39 million deaths by 2050. Two pathways accelerate the spread of antibiotic resistance genes (ARGs): vertical gene transfer (VGT), where resistance is inherited during cell division, and horizontal gene transfer (HGT), which includes conjugation, transformation, and phage-mediated exchange. Although antibiotics are known drivers of resistance, their environmental concentrations—often far below clinical minimum inhibitory concentrations (MICs)—remain poorly understood in terms of long-term, real-world effects on bacterial evolution. Given that more than 90% of consumed antibiotics are excreted unmetabolized and widely enter natural ecosystems, understanding how low-level residues shape resistance dynamics is an urgent research priority.
A study (DOI:10.48130/biocontam-0025-0005) published in Biocontaminant on 07 November 2025 by Yue Wang’s & Jie Wang’s team, Tiangong University, demonstrates that even low, environmentally relevant concentrations of antibiotics can significantly accelerate the persistence and spread of antibiotic resistance genes through both vertical inheritance and horizontal gene transfer.
To investigate how environmentally relevant antibiotics affect the spread and stability of ARGs, the researchers established a 10-day vertical transmission system, complemented by mathematical modeling, to predict long-term shifts in plasmid-carrying versus plasmid-free bacteria. They also constructed intra- and intergeneric conjugation systems and a transformation model using Acinetobacter baylyi and plasmid pWH1266 to assess HGT under low-dose exposure, while applying RT-qPCR, ROS assays, membrane permeability tests, ATP measurements, and HPLC to probe underlying mechanisms. Results showed that kanamycin, ampicillin, and streptomycin increased resistant bacteria and stabilized resistance over time, whereas tetracycline slowed early growth but still maintained resistance, partly due to bacterial degradation detected by HPLC. MIC measurements confirmed stable or enhanced resistance, with streptomycin inducing new cross-resistance. Gene expression analyses demonstrated strong upregulation of tolC, oxyR, soxR, recA, ompA, and ompC, linking ROS accumulation and membrane remodeling to persistent ARG inheritance. Modeling revealed that, without antibiotics, plasmid-free bacteria dominate, but under antibiotic pressure, plasmid-bearing strains expand and persist. Conjugation and transformation assays further showed that low-dose antibiotics (0.005–5 mg/L) boosted plasmid transfer and transformation by up to fivefold through elevated ROS, increased membrane permeability, higher ATP, and activation of conjugation genes, whereas high doses suppressed HGT by reducing ATP and cell viability. Modeling confirmed that such low-level antibiotics accelerate long-term HGT and increase overall transformant abundance.
The findings highlight a critical but often overlooked environmental challenge: even trace antibiotic pollution can substantially accelerate both the inheritance and exchange of resistance genes. This means that treated wastewater, agricultural runoff, aquaculture systems, and hospital discharge waters may act as hotspots that amplify resistance spread, even when antibiotic concentrations are far below therapeutic levels. By demonstrating that sub-MIC antibiotic residues enhance both VGT and HGT, the study suggests that environmental exposure thresholds and discharge standards may require re-evaluation. Improved surveillance of antibiotic residues and mitigation strategies will be essential to contain the environmental drivers that fuel the global rise of antibiotic resistance.
###
References
DOI
Original Source URL
https://doi.org/10.48130/biocontam-0025-0005
Funding information
This study was financially supported by the National Natural Science Foundation of China (Nos. 42307529 and 42577486), Hebei Natural Science Foundation (Nos. C2023110006 and E2023110001), the Research Fund of Tianjin Key Laboratory of Aquatic Science and Technology (No. TJKLAST-PT-2021-04), and Cangzhou Institute of Tiangong University (No. TGCYY-F-0103).
About Biocontaminant
Biocontaminant is a multidisciplinary platform dedicated to advancing fundamental and applied research on biological contaminants across diverse environments and systems. The journal serves as an innovative, efficient, and professional forum for global researchers to disseminate findings in this rapidly evolving field.
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Antibiotics at environmentally relevant concentrations can promote the dissemination of antibiotic resistance via both vertical and horizontal gene transfer
