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Understanding the composition and spatial distribution patterns of microbial communities in plateau peatland soils is crucial for preserving the structural and functional stability of highland wetlands. We collected 50 soil samples from the core conservation area of Zoige peatland along horizontal and vertical distributions to analyze the soil bacterial and fungal diversity by using high-throughput sequencing technology, combined with Mantel tests and multiple regression on matrices (MRM) statistical methods, as well as the spatial distribution characteristics of community structure similarity at a local scale. The results showed that the dominant soil bacterial and fungal groups were Chloroflexi (accounting for 33.2% and 25.1% of the total bacterial community in horizontal and vertical directions, respectively) and Ascomycota (54.7% and 76.4%). The similarity of microbial community structure in both horizontal and vertical directions decreased with increasing spatial distance of the sampling points. The turnover rates of bacterial and fungal communities in the vertical direction were 8.8 and 8.6 times as those in the horizontal direction, respectively. Based on the relative abundance of the communities, we classified microbes into six groups. As the number of rare species in the community increased, the slope of community distance decay decreased. The conditionally rare or abundant taxa (CRAT) category group showed the most similar spatial distribution characteristics to the total microbial community. Mantel analysis indicated that soil organic carbon, total nitrogen, and available phosphorus were key factors driving the distribution of bacterial and fungal communities in the horizontal direction, while soil organic carbon, available carbon, pH, and soil bulk density were the main factors determining the vertical distribution. MRM analysis further showed that both soil physicochemical indicators and spatial distance significantly affected the assembly of microbial communities, where soil factors explained more about the vertical distribution of microbial communities than the horizontal distribution. The impact of soil factors on microbial community distribution was much greater than that of spatial factors through diffusion limitation. In summary, the microbial communities in the plateau peatland soils exhibited more pronounced vertical distribution differences and environmental response characteristics.

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It is important to investigate the responses of greenhouse gases to climate change (temperature, precipitation) and anthropogenic factors in plateau wetland. Based on the DNDC model, we used meteorological, soil, and land cover data to simulate the soil CO2 emission pattern and its responses to climate change and anthropogenic factors in Guizhou, China. The results showed that the mean soil CO2 emission flux in the Caohai Karst Plateau Wetland was 5.89 ± 0.17 t·C·ha-1·yr-1 from 2000 to 2019, and the annual variation showed an increasing trend with the rate of 23.02 kg·C·ha-1·yr-1. The soil total annual mean CO2 emissions were 70.62 ± 2.04 Gg·C·yr-1 (annual growth rate was 0.28 Gg·C·yr-1). Caohai wetland has great spatial heterogeneity. The emissions around Caohai Lake were high (the areas with high, middle, and low values accounted for 3.07%, 70.96%, and 25.97%, respectively), and the emission pattern was characterized by a decrease in radiation from Caohai Lake to the periphery. In addition, the cropland and forest areas exhibited high intensities (7.21 ± 0.15 t·C·ha-1·yr-1 and 6.73 ± 0.58 t·C·ha-1·yr-1, respectively) and high total emissions (54.97 ± 1.16 Gg·C·yr-1 and 10.24 ± 0.88 Gg·C·yr-1, respectively). Croplands and forests were the major land cover types controlling soil CO2 emissions in the Caohai wetland, while anthropogenic factors (cultivation) significantly increased soil CO2 emissions. Results showed that the soil CO2 emissions were positively correlated with temperature and precipitation; and the temperature change had a greater impact on soil respiration than the change in precipitation. Our results indicated that future climate change (increased temperature and precipitation) may promote an increase in soil CO2 emissions in karst plateau wetlands, and reasonable control measures (e.g. returning cropland to lakes and reducing anthropogenic factors) are the keys to controlling CO2 emissions.

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Viruses exist anywhere on earth where there is life, and among them, virus-encoded auxiliary metabolic genes (AMGs) can maintain ecosystem balance and play a major role in the global ecosystem. Although the function of AMGs has been widely reported, the genetic diversity of AMGs in natural ecosystems is still poorly understood. Exploring the genetic diversity of viral community-wide AMGs is essential to gain insight into the complex interactions between viruses and hosts. In this article, we studied the phylogenetic tree, principal co-ordinates analysis (PCoA), α diversity, and metabolic pathways of viral auxiliary metabolism genes involved in the pentose phosphate pathway (PPP) through metagenomics, and the changes of metabolites and genes of host bacteria were further studied by using Pseudomonas mandelii SW-3 and its lytic phage based on metabolic flow and AMGs expression. We found that the viral AMGs in the Napahai plateau wetland were created by a combination of various external forces, which contributed to the rich genetic diversity, uniqueness, and differences of the virus, which promoted the reproduction of offspring and better adaptation to the environment. Overall, this study systematically describes the genetic diversity of AMGs associated with the PPP in plateau wetland ecosystems and further expands the understanding of phage-host unique interactions.

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Pseudomonas mandelii SW-3, isolated from the Napahai plateau wetland, can survive in cold environments. The mechanisms underlying the survival of bacteria in low temperatures and high altitudes are not yet fully understood. In this study, the whole genome of SW-3 was sequenced to identify the genomic features that may contribute to survival in cold environments. The results showed that the genome size of strain SW-3 was 6,538,059 bp with a GC content of 59%. A total of 67 tRNAs, a 34,110 bp prophage sequence, and a large number of metabolic genes were found. Based on 16S rRNA gene phylogeny and average nucleotide identity analysis among P. mandelii, SW-3 was identified as a strain belonging to P. mandelii. In addition, we clarified the mechanisms by which SW-3 survived in a cold environment, providing a basis for further investigation of host-phage interaction. P. mandelii SW-3 showed stress resistance mechanisms, including glycogen and trehalose metabolic pathways, and antisense transcriptional silencing. Furthermore, cold shock proteins and glucose 6-phosphate dehydrogenase may play pivotal roles in facilitating adaptation to cold environmental conditions. The genome-wide analysis provided us with a deeper understanding of the cold-adapted bacterium.

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Viruses play an important role in microbial community structure and biodiversity by lysing host cells, and can also affect host metabolic pathways by expressing auxiliary metabolic genes (AMGs). As a unique low-latitude, high-altitude seasonal plateau wetland in China, Napahai has high research value. However, studies on the genetic diversity of AMGs and viruses associated with DNA biosynthesis have not been reported. Based on metagenomics, with the phylogenetic tree, PCoA, and α diversity analysis, we found that three DNA biosynthesis-related viral AMGs (cobS, mazG, and purM) in the Napahai plateau wetland were rich in genetic diversity, uniqueness, and differences compared with other habitats and host sources. Through the KEGG metabolic pathway and metabolic flow analysis of Pseudomonas mandelii (SW-3) and phage (VSW-3), the AMGs (cobS, mazG, and purM) genes of the three related viruses involved in DNA biosynthesis were upregulated and their expression increased significantly. In general, we systematically described the genetic diversity of AMGs associated with DNA biosynthesis in plateau wetland ecosystems and clarified the contribution of viral AMGs in the Napahai plateau wetland to DNA biosynthesis, as well as the changes of metabolites and genes. It further expands the understanding of phage-host interactions, which is of great significance for further revealing the role of viral AMGs in the biological evolution and biogeochemical cycle of wetland ecosystems.

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We focused on exploring the diversity of viruses in the Napahai plateau wetland, a unique ecosystem located in Yunnan, China. While viruses in marine environments have been extensively studied for their influence on microbial metabolism and biogeochemical cycles, little is known about their composition and function in plateau wetlands. Metagenomic analysis was employed to investigate the viral diversity and biogeochemical impacts in the Napahai wetland. It revealed that the Caudoviricetes and Malgrandaviricetes class level was the most abundant viral category based on phylogenetic analysis. Additionally, a gene-sharing network highlighted the presence of numerous unexplored viruses and demonstrated their unique characteristics and significant variation within the viral community of the Napahai wetland. Furthermore, the study identified the auxiliary metabolic genes (AMGs). AMGs provide phages with additional functions, such as protection against host degradation and involvement in metabolic pathways, such as the pentose phosphate pathway and DNA biosynthesis. The viruses in the Napahai wetland were found to influence carbon, nitrogen, sulfur, and amino acid metabolism, indirectly contributing to biogeochemical cycling through these AMGs. Overall, the research sheds light on the diverse and unique viral communities in the Napahai plateau wetland and emphasizes the significant roles of viruses in microbial ecology. The findings contribute to a deeper understanding of the characteristics and ecological functions of viral communities in plateau wetland ecosystems.

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With the development of global industrialization, carbon neutrality has become an issue that we must be paid attention to. Microorganisms not only have an important impact on the carbon chemical cycle between the Earth's biosphere and biogeography but also play a key role in maintaining the global organic carbon balance. Wetlands are the main reservoir of organic carbon in the mainland of China, and wetland carbon sinks are indispensable for China to achieve the goal of "dual carbon," and China has taken the consolidation and improvement of wetland carbon sink capacity as an important part of the carbon peaking action plan. As a unique low-latitude, high-altitude seasonal plateau wetland in China, Napahai shows high research value. However, the role of microbes in maintaining dissolved organic carbon balance in this area has not been reported. In the study, six carbon fixation genes, accA, aclB, acsA, acsB, cbbL, and rbcL, were analyzed based on metagenomics to elucidate the rich genetic diversity, uniqueness and differences in the Napahai plateau wetland. It was found that the microbial diversity in the Napahai plateau wetland was different from other habitats. In addition, the aclB gene, a rare taxon with high genetic diversity and rich species in the Napahai plateau wetland, played a key role in the microbial metabolic pathway. Finally, the construction of a metabolic pathway through the Kyoto encyclopedia for genes and genomes revealed the contribution of microbes to carbon fixation and the role of microbes in maintaining the organic carbon balance of the Napahai plateau wetland.

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Virus plays important roles in regulating microbial community structure, horizontal gene transfer, and promoting biological evolution, also augmenting host metabolism during infection via the expression of auxiliary metabolic genes (AMGs), and thus affect biogeochemical cycling in the oceans. As the "kidney of the earth," wetlands have rich biodiversity and abundant resources. Based on metagenomic data, 10 AMGs associated with sulfur cycling, i.e., tusA, moaD, dsrE, soxA, soxB, soxC, soxD, soxX, soxY, and soxZ, were analyzed in Napahai plateau wetland. The phylogenetic trees of AMGs involved in sulfur metabolism from different habitats and host origins were constructed. Combined with principal coordinate analysis, it revealed that most AMGs associated with sulfur metabolism clustered separately, indicating the abundance and uniqueness in this region. The sulfur metabolism pathways involved by AMGs were mainly SOX systems, among which sulfur oxidation was associated with moaD and dsrE genes, while sulfur transport was related to tusA genes. It provides an insight into the biogeochemical sulfur cycling in plateau wetlands and lays the foundation for further study on the co-evolution of virus and host.

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The thawing of dormant plateau permafrost emits nitrous oxide (N2O) through wetlands; however, the N2O production mechanism in plateau wetlands is still unclear. Here, we used the 15N-18O double tracer technique and metagenomic sequencing to analyze the N2O production mechanism in the Yunnan-Kweichow and Qinghai-Tibet plateau wetlands during the summer of 2020. N2O production activity was detected in all 16 sediment samples (elevation 1020-4601 m: 2.55 ± 0.42-26.38 ± 3.25 ng N g-1 d-1) and was promoted by nitrifier denitrification (ND). The key functional genes of ND (amoA, hao, and nirK) belonged to complete ammonia oxidizing (comammox) bacteria, and the key ND species was the comammox bacterium Nitrospira nitrificans. We found that the comammox bacterial species N. nitrificans and the ammonia oxidizing bacterial (AOB) species Nitrosomonas europaea cooperate to produce N2O in the plateau wetland sediments. Furthermore, we inferred that environmental factors (elevation and total organic matter (TOM)) influence the cooperation pattern via N. nitrificans, thus affecting the N2O production activity in the plateau wetland sediments. Our findings advance the mechanistic understanding of nitrifiers in biogeochemical cycles and global climate change.

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In this study, the occurrence, distribution, and ecological risk of 40 commonly used antibiotics, including 15 sulfonamides (SAs), 9 fluoroquinolones (FQs), 7 macrolides (MCs), 3 tetracyclines (TCs), 2 chloramphenicols (CAPs), and 4 other categories, in the aquatic environment of the karst plateau wetland Caohai of the Yangtze River basin in southwestern China are reported. In total, 27 antibiotics were detected, with the detection rate ranging from 5% to 100%. The total concentration at each site ranged from 21.8 ng/L to 954 ng/L, with the average concentration being 189 ng/L. FQs and MCs were the most predominant categories, contributing 29.3% and 25.0% of the total antibiotic burden. The five most commonly detected antibiotics were ciprofloxacin (CIP), oxytetracycline (OTC), acetyl sulfamethoxazole (ASMZ), norfloxacin (NOR), and florfenicol (FF). The spatial distribution of the total concentration at each site demonstrated a decreasing trend from the southeastern area upstream adjoining the main counties to the northwestern area downstream, indicating that human activities have a great impact. Meanwhile, the natural attenuation rates of different types of antibiotics in the direction of flow ranged from 17.6% to 100%, which implied the natural purification potential of the wetland for antibiotics. The cluster analysis results indicated that domestic sewage and wastewater from agriculture and animal husbandry were the main sources of contamination in the surrounding wetland. Risk quotients (RQs) assessment showed that most of the individuals were at low to medium risk and that the adverse risks posed by mixtures of antibiotics were higher than those posed by the individual antibiotics.

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The recent discovery of complete ammonia oxidation (comammox) has increased our understanding of nitrification. Although comammox has been shown to play an important role in plain wetland ecosystems, studies of comammox contribution are still limited in plateau wetland ecosystems. Here, we analyzed the abundance, activity, community and biogeochemical mechanisms of the comammox bacteria in Yunnan-kweichow and Qinghai-Tibet plateau wetlands from elevations of 1000-5000 m. Comammox bacteria were widely distributed in all 16 sediment samples with abundances higher than 0.96 ± 0.26 × 107 copies g-1 (n = 16). Comammox showed high activity (1.18 ± 0.17 to 1.98 ± 0.08 mg N kg-1 d-1) at high-elevation (3000-5000 m) and dominated the nitrification process (activity contribution: 37.20 - 60.62%). The activity contribution of ammonia-oxidizing bacteria (1.07 ± 0.08 to 2.79 ± 0.35 mg N kg-1 d-1) dominated the nitrification process (44.55 - 64.15%) in low-elevation (1000-3000 m) samples. All detected comammox Nitrospira belonged to clade A, while clade B was not detected. Elevation always had a strongest effect on key comammox species. Thus, we infer that elevation may drive the high relative abundance of the species Candidatus Nitrospira nitrificans (avg. 12.40%) and the low relative abundance of the species Nitrospira sp. SG-bin2 (avg. 4.75%) in high-elevation samples that showed a high comammox activity (avg. 1.62 mg N kg-1 d-1) and high contribution (avg. 46.08%) to the nitrification process. These results indicate that comammox may be an important and currently underestimated microbial nitrification process in plateau wetland ecosystems.

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Fulvic acids (FAs) are known to regulate the fate of mercury (Hg) in sediments, but the key effects of their properties are still unclear. In this study, field investigations and simulation experiments were conducted in a heavy metal-polluted wetland to identify FA characteristics and their association with the production and bioaccumulation of methylmercury (MeHg). Compared to permanently inundated areas (PIA), seasonally inundated areas (SIAs) had lower total Hg levels in sediments, whereas higher MeHg levels in sediments (0.20 ± 0.09 ng g-1 vs. 0.55 ± 0.31 ng g-1) and benthos (0.25 ± 0.22 ng g-1 vs. 1.62 ± 1.78 ng g-1). Meanwhile, the THg and MeHg concentrations in the same macrophyte species between PIA and SIA also followed a similar rule with benthos. FA-bound Hg in the sediment was significantly correlated with MeHg in the sediment (p < 0.01), as well as THg and MeHg in benthos (p < 0.05), indicating that FAs have the capacity to promote MeHg production and bioaccumulation. Moreover, the FAs in the sediments of the SIA had lower fractions and alkyl C/O-alkyl C ratios, but higher molecular weights and THg/MeHg concentrations than those in the PIA, indicating that FAs in SIA have increased bioavailability and enhanced competition for Hg, favoring significantly elevated FA-bound Hg levels. Biological exposure testing further demonstrated that FAs extracted from SIA had a greater ability to increase the production and bioaccumulation of MeHg than those extracted from PIA. Overall, these results highlight that the molecular composition and sources of FAs, excluding their concentrations, are one of important factors responsible for the obvious spatial heterogeneity of MeHg in sediments and aquatic organisms in the wetland.

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Isoetes hypsophila Hand.-Mazz. is an Endangered quillwort living in plateau wetlands in China. In the present study, the complete chloroplast genome of I. hypsophila was assembled. It is a circular form of 146,362 bp in length, comprising a pair of inverted repeat (IR) regions of 13,691 bp, a large single copy (LSC) of 91,741 bp, and a small single copy (SSC) of 27,239 bp. After annotation, a total of 135 genes were predicted, which are 84 encode proteins 37 tRNA and 8 rRNA. The phylogenetic analysis indicated that I. hypsophila clustered with a clade of I. sinensis, I. taiwanensis and I. yunguiensis with strong support value. The chloroplast genome will contribute to further research and conservation of I. hypsophila.

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Dam impoundment, which rapidly changes hydrologic regimes and greatly alters aquatic environments, plays a critical role in the seed germination and seedling growth of wetland plants, especially influencing their seed banks. In this study, a soil seed bank experiment was carried out along a water level gradient for the Lake Lashi wetland in the Northwest Yunnan Plateau of China. The objectives of this study were to determine the effect, driver and dynamic mechanism of dam impoundment on the soil seed bank of plateau wetlands using partial least squares (PLS) regression and chaotic dynamic methods. The results showed that the soil seed bank had significant differences in seed density, species composition, and water ecotype of the plant species between the flood zone (perennially flooded area, seasonally flooded area, and flood plain area) and nonflood zone (control area) in the plateau wetland. The seed bank density was obviously lower in the perennially flooded area and higher in the seasonally flooded area and flood plain area, with values that were 39.88%, 153.53%, and 146.47% that of the control area, respectively. After dam impoundment, the number of plant species gradually increased; however, the dominance of the dominant species became less obvious, and the species diversity indices decreased significantly, e.g., by 15.47% for the Simpson diversity index and 72.39% for the Shannon Wiener diversity index. Our study showed that dam impoundment has made the Lake Lashi wetland complex chaotic ecosystem switch between order and disorder through self-organization and that the species composition of the soil seed bank continuously experienced self-adaptation. These results provide a reference for scientific evaluations of the effects of dam impoundment on wetland ecosystems and provide guidance for the protection and management of plateau wetland ecosystems.

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Land use changes have significant modifications on soil conditions, which is likely to induce alterations in the soil bacterial communities. Little is known about the respective contributions of soil variables to these changes in bacterial communities. For this study, high-throughput sequencing technology was applied to measure the change in bacterial community compositions under the effects of soil variables across three land-use types (i.e., reference, degraded, and agricultural wetlands) in the Napahai plateau. Compared with the reference wetland, a pronounced decrease (1.5-5.3 times) in soil water content, soil organic matter, and total and available nitrogen was observed in degraded and agricultural wetlands. However, a conspicuous increase (1.3-5.7 times) was found for the total and available phosphorus, and potassium. Land use also strongly affected the taxonomic composition of soil bacterial assemblages, changing the normalized ratio of Acidobacteria to Proteobacteia, or to δ-proteobacteia. Soil properties had different contributions to the variations in abundance composition of bacterial community. Soil available phosphorus and potassium were the best predictors for changes in bacterial community composition, explaining 80.9% and 82% of the variations, respectively. In contrast, soil organic matter, carbon/nitrogen, total phosphorus, and total and available nitrogen accounted for 58.7-72.7% of the variations in bacterial community composition. Soil pH (24.6%) and soil water content (40.4%) had a minor contribution. Our data suggested that the compositional alterations of microbial communities following land-use change were likely realized through modifications in the availability of primary soil nutrients in the Napahai plateau wetlands.

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The lytic cold-active bacteriophage VSW-3, belonging to the Podoviridae family and infecting the host Pseudomonas fluorescens SW-3, was isolated from the Napahai plateau wetland in China. With the development of sequencing technology, the study of Pseudomonas genomic diversity has increased; however, knowledge of cold-active phages infecting Pseudomonas is limited. The newly sequenced phage VSW-3 was classified based on virion morphology by transmission electron microscope. Sequence analysis revealed that the genome size was 40,556 bp with an overall GC content of 57.54 % and 46 open reading frames. The genome was organized into several modules containing genes for packaging, structural proteins, replication/transcription, and phage lysis. The sequence contained 45 potential promoters, 3 transcription terminators, and yet no tRNAs. This is the first report of cold-active Pseudomonas fluorescens bacteriophage genome sequencing.

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