Minfei Jian

To address yttrium (Y) contamination from ion adsorption mining, this study developed a combined microbial phytoremediation strategy for dual objectives: ensuring crop safety in Lactuca sativa and enhancing Y recovery by Solanum nigrum. Two specific microbial consortia were constructed from rare earth tailings isolates: inoculant I (bacterial: Enterobacter sp., Serratia sp., Bacillus sp.) applied to L. sativa, and inoculant II (fungal: Penicillium sp., Aspergillus sp., Talaromyces sp.) applied to S. nigrum. Inoculant I increased L. sativa biomass by 26% while reducing Y content in roots and rhizosphere soil solution by 47% and 56%, respectively, potentially through down-regulation of amino acid metabolites. Inoculant II increased Y content in the S. nigrum rhizosphere soil solution by 89%, linked to up-regulation of organic acids and coumarin derivatives. Both consortia reduced plant stress markers and enhanced soil enzyme activities. These findings demonstrate that specialized microbial consortia can differentially regulate Y behavior in the rhizosphere—immobilizing it in a crop for food safety, while enhancing its bioavailability for a hyperaccumulator—offering a targeted strategy for managing rare earth element-contaminated agricultural soils.

Gut microbiota are integral to host health and ecological adaptation, yet their interactions with environmental microbial communities remain understudied in migratory waterbirds. Using high-throughput 16S rRNA gene sequencing, we compared gut microbiota of captive and wild Siberian cranes and their associations with soil microbiota in the Poyang Lake wetlands. Alpha diversity was significantly higher in soil than in gut microbiota, with captive cranes exhibiting greater microbial richness and evenness than wild individuals. Beta diversity analysis revealed distinct gut and soil microbiota, with partial overlap between captive and wild crane gut microbiota. Firmicutes dominated gut communities, with Ligilactobacillus and Romboutsia enriched in captive cranes, whereas Acidobacteria were predominant in soil. Escherichia-Shigella was more abundant in wild cranes and soil. Linear discriminant analysis (LDA) effect size (LEfSe) analysis identified 34 differentially enriched taxa, and microbial network analysis indicated stronger gut–soil microbial associations than those between captive and wild hosts. Network analysis further revealed distinct co-occurrence patterns between captive and wild groups, suggesting potential shifts in microbial interaction structures under different living conditions. These findings provide preliminary insights that may inform future conservation strategies for Siberian cranes.

Gut microbiota are integral to host health and ecological adaptation, yet their interactions with environmental microbial communities remain understudied in migratory waterbirds. Using high-throughput 16S rRNA gene sequencing, we compared gut microbiota of captive and wild Siberian cranes (Leucogeranus leucogeranus) and their associations with soil microbiota in the Poyang Lake wetland. Alpha diversity was significantly higher in soil than in gut microbiota, with captive cranes exhibiting greater microbial richness and evenness than wild individuals. Beta diversity analysis revealed distinct gut and soil microbiomes, with partial overlap between captive and wild crane gut microbiota. Firmicutes dominated gut communities, with Ligilactobacillus and Romboutsia enriched in captive cranes, whereas Acidobacteria were predominant in soil. Potential pathogens (e.g., Escherichia-Shigella) were more abundant in wild cranes and soil. LEfSe analysis identified 34 differentially enriched taxa, and microbial network analysis indicated stronger gut–soil microbial associations than those between captive and wild hosts, suggesting that environmental microbiota may serve as reservoirs for host colonization. These findings highlight the ecological dynamics shaping gut microbiota in response to captivity and environmental exposure, providing insights into microbial contributions to conservation strategies for Siberian cranes.

Lakes offer a primary setting for the collection and spread of antibiotic resistance genes (ARGs) within natural habitats, so it is of great importance and urgency to investigate the characteristics of ARGs in such aquatic ecosystems. Herein, the occurrence and distribution of microbial populations, ARGs, and mobile genetic elements (MGEs) in Poyang Lake, the largest freshwater lake in China, were analyzed in-depth through metagenomic sequencing. Surface water and sediment samples were examined simultaneously at 10 sampling sites covering the inlets of five tributaries and central lake areas. Results showed that the antibiotic concentration was at a low level in both surface water and sediment. Proteobacteria and Actinobacteria were the two most prevalent phyla across all sampling sites. The surface water displayed a greater relative abundance of ARGs than the sediment. Multidrug resistance genes were the most abundant and diverse ARGs. Gene uppP was the most abundant ARG in both the surface water and sediment samples. ARGs in the sediment showed a decreasing trend from inlet to outlet of Poyang Lake, while in the water, the relative abundance of ARGs increased first and then decreased from inlet to outlet. ARG levels in Poyang Lake are thought to be closely related to human activity. A broad spectrum of MGEs series was recognized in both surface water and sediment samples; the abundance of MGEs was consistent with ARGs’ abundance. Additionally, the makeup of the microbial community significantly influenced the resistome, suggesting that the composition of ARGs was largely affected by the microbial community. These findings indicate that lake water can act as a significant medium for ARGs dispersion, and the clustering and spread of ARGs are prone to the effects of human activities in aquatic habitats.

As a new type of pollutant, microplastics have attracted increasing attention. Microplastics in aquatic ecosystems are accumulating at an unprecedented scale, causing significant environmental and economic impacts. In this study, sediments and different types of microplastic samples were collected from the Grus leucogeranus Reserve of Wuxing Reclamation Farm of Poyang Lake, which is the largest freshwater lake in China. The main types of microplastics were film (PE), debris (PP1), fiber (PP2), and foam (PS), and the polymers were identified as polyethylene, polypropylene, and polystyrene in the study area. The structures of microbial communities (fungi and bacteria) were identified using 16S high-throughput sequencing. The results showed that there was no significant difference in the Ace and Chao of bacteria between the surface of PE and PP1 and that of the surrounding sediments (P>0.05), whereas PP2 and PS were significantly lower than those in surrounding sediments (P0.05), and PP1 and PP2 were significantly lower than those in surrounding sediments (P<0.05). The species diversity Shannon and Simpson index of bacteria and fungi on different types of microplastic surfaces were lower than that of sediment. The bacterial communities on the sediment and microplastic surface mainly included Proteobacteria and Bacteroidetes. In the fungal community, Basidiomycota, Ascomycota, and Chytridiomycota were the dominant bacteria. Through KEGG functional prediction, it was found that most of the metabolic pathways with a significant difference between bacteria and sediments on the surface of microplastics and with an abundance ratio higher than 1% were related to metabolism. Compared with that of sediment, the metabolic pathways of PE and PP2 on microplastic surfaces were down-regulated mainly in cell motility, signal transduction, and carbohydrate metabolism, whereas the energy metabolism, general and global metabolism pathways, and cofactor metabolism were up-regulated. Compared with that of sediment, the bacterial metabolic pathways of PS and PP1 on microplastic surfaces were down-regulated, mainly including general and global metabolic pathways, translation, and exogenous biodegradation, and cell motility and signal transduction were up-regulated. However, the abundance of other functional genes in sediments and microplastic samples showed little difference. The results indicated that microplastics can change the structure of microbial communities, and the microbial community on the surface of microplastics could catalyze metabolic reactions and promote the decomposition of microplastics. The study of microplastic surface microbial structure in Poyang Lake can support management decisions to protect the ecological integrity of the lake.

Human-induced changes in landscapes are one of the major drivers of wetland loss and degradation. The Poyang Lake wetland in China has been experiencing severe degradation due to human disturbance and landscape modification. Indicators to assess the condition of this wetland are thus needed urgently. Here, a landscape-based multi-metric index (LMI) is developed to evaluate the condition of the Poyang Lake wetland. Twenty-three candidate metrics that have been applied to wetland health assessment in published studies were tested. Metrics that show strong discriminative power to identify reference and impaired sites, having significant correlations with either benthic macroinvertebrate- or vegetation-based indices of biotic integrity (B-IBI or V-IBI), were chosen to form the LMI index. Five of these metrics (largest patch index, modified normalized differential built-up index, Shannon’s diversity index, connectance index, and cultivated land stress index) were selected as our LMI metrics. A 2 km buffer zone around sample sites had the strongest explanatory power of any spatial scale on IBIs, suggesting that protecting landscapes at local scales is essential for wetland conservation. The LMI scores ranged between 1.05 and 5.00, with a mean of 3.25, suggesting that the condition of the Poyang Lake wetland is currently in the “fair” category. The areas along lakeshores were mainly in poor or very poor conditions, while the less accessible inner areas were in better conditions. This study demonstrates significant links between landscape characteristics and wetland biotic integrity, which validates the utility of satellite imagery-derived data in assessing wetland health. The LMI method developed in this study can be used by land managers to quickly assess broad regions of the Poyang Lake wetland.

To explore the effects of different electron acceptors on soil methane emission and responses of soil microorganisms to different light conditions, a strict anaerobic 20-day incubation experiment was conducted with eight treatments: darkness + Fe³⁺ (DF); darkness + NO₃^- (DN); darkness +SO₄^2- (DS); darkness + distilled water (DCK); light + Fe³⁺ (LF); light + NO₃^- (LN); light +SO₄^2- (LS); light + distilled water (LCK). The changes of methane concentration in the anaerobic incubation flask and the variation of the abundance of bacteria, archaea, fungi and six soil functional genes were analyzed. Results showed that soil methane emission under NO₃^-, SO₄^2- addition and control (CK) was significantly lower under light conditions than dark, except the Fe³⁺ treatment. DN, DCK and LF treatments had the highest abundance of bacteria, fungi and archaea genes, respectively. The gene abundance of methanogenic mcrA, sulfate-reducing bacteria Dsr, and carbon-fixing CbbL were significantly up-regulated in the LF, while that of methanotrophs pmoA, iron-reducing bacteria Geo, and denitrifying bacteria nosZ were significantly up-regulated in the LN, DCK and LCK, respectively. Results of Pearson correlation and RDA analysis showed that CH₄ emission was significantly positively correlated with CO₂ concentration, pH, ammonium-nitrogen, and total N contents, and negatively correlated with N₂O concentration, Eh, nitrate, and total C contents. Under dark condition, methane emission was positively correlated with archaea and pmoA genes abundance, and negatively correlated with other genes abundance. Under light condition, methane emission was negatively correlated with the abundance of soil microbe and functional genes. In general, methane emission under light condition was significantly lower than that under dark condition (except for the Fe³⁺ treatment). These results showed that it was helpful to reduce methane emission under light condition, but the increase or decrease of methane emission was closely related to the type of electron acceptors and the functional responses of soil micro-organisms.