Microbial Ecology最新文献

Understanding how long-term agricultural practices affect soil bacteriome is essential for sustainable land management. In the Guadalquivir Marshes of southwestern Spain, which encompass both Doñana National Park and one of Europe's most productive rice cultivation areas, decades of rice farming have transformed natural wetlands into artificial agroecosystems. Although bacterial degradation in cultivated soils has been previously suggested, comparative analyses between rice paddies and adjacent natural wetlands remain scarce.Here, we characterized the soil bacteriome across a cultivation gradient by comparing undisturbed natural marshes, within Doñana National Park, with rice fields cultivated for 25 years (Cantarita) and 80 years (Mínima 2). Using full 16S rRNA gene via long-read metabarcoding and standardized soil physicochemical assays, we analysed taxonomic composition, environmental associations, and predicted functional profiles.Our results reveal a progressive restructuring of bacterial communities with increased cultivation time, notably a significant enrichment of Chloroflexota (especially Anaerolineae) and a decline in Actinomycetota and Planctomycetota in paddy soils. Functional predictions indicated a higher potential for denitrification in cultivated soils-likely involving Chloroflexota taxa-compared to more diverse nitrogen pathways in natural sites. These shifts were strongly associated with changes in pH, electrical conductivity, calcium carbonate, and nitrate levels. Remarkably, most bacterial differences were already evident within the first 25 years of cultivation, underscoring the rapid ecological impact of intensive rice cultivation.Notably, we identified specific bacterial groups (Anaerolineae and Nocardioides in paddy soils; Euzebya, Rubrobacter, and Planctomycetota in natural wetlands), whose enrichment was associated with soil type. This approach highlights the value of integrating bacterial-based assessments into sustainable wetland management strategies.

Microbe-derived antimicrobial peptides (AMPs) can shape gut community structure; however, their contribution to disease-associated dysbiosis remains poorly understood. We assembled fecal metatranscriptomes from individuals with normal weight (NW), obesity (O), and obesity with metabolic syndrome (OMS), yielding 51,087 non-human transcripts. We screened 1,095 small open reading frames (smORFs) using AMP-prediction algorithms combined with stringent post-hoc bioinformatics filters identifying 51 high-confidence AMP candidates. Most matched bacterial homologs, predominantly Faecalibacterium prausnitzii, while eight mapped to plasmids or bacteriophages. Differential expression identified two and four AMPs overexpressed in O and OMS, respectively. Two of them were originated from chromosomes, three from phages, and one from plasmid. Notably, the over-expression of these AMPs was negatively correlated with healthy-associated bacteria and positively correlated with obesity-enriched taxa. Furthermore, these AMPs were broadly detectable across 372 external gut metatranscriptomes (prevalence up to 94% of the samples) indicating conservation within the human gut microbiome and highlighting mobile elements as an overlooked reservoir of transcriptionally active AMPs. Using DNA virome sequencing and prophage analyses, we suggested phage origin of the transcribed AMPs. We further synthesized a phage-encoded AMP (AMP-3020), demonstrating broad-spectrum activity against Gram-positive and Gram-negative bacteria, without detectable cytotoxicity toward human immune T cells. This supports the idea that phages could encode functional AMPs capable of shaping gut community structure by suppressing diverse bacteria without harming host immune cells. Our gut metatranscriptome-virome profiling revealed a conservative core of actively transcribed, plasmid- and phage-encoded AMPs with exploratory associations to obesity/MetS. These findings support mobile-element AMPs as candidate ecological regulators and motivate validation in larger cohorts and mechanistic models.

Rare microbial lineages, such as members of the candidate phyla radiation (CPR) bacteria and Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota, and Nanohaloarchaeota (DPANN) archaea, are increasingly recognized as key components of microbial communities in natural systems. Yet, their global distribution, biogeographic patterns, and broader role in shaping microbial community structure across diverse ecosystems remain poorly characterized. Here, we analyzed 2860 metagenomes spanning nine ecosystems using a curated reference database and a bias-aware taxonomic filtering approach to quantify the richness, relative abundance, and structural influence of low-abundance microbial taxa on community structure across a wide range of ecosystems. Our findings reveal that rare taxa, primarily CPR and DPANN, disproportionately shape microbial community dissimilarities across global ecosystems. We observed that the richness of these two groups, that drives community structure variation, increases with latitude, peaking in temperate regions, thereby contrasting classical latitudinal diversity patterns and suggesting unique biogeographic drivers. CPR and DPANN were predominantly enriched in free-living environments, particularly groundwater and soil, then in host-associated habitats, consistent with niche specialization shaped by environmental filtering and dispersal constraints. These findings challenge abundance-centric assumptions in microbial ecology and highlight the need to integrate low-abundance taxa into macroecological frameworks. Fully resolving their ecological functions, however, will require targeted experimental and multi-omics investigations.

Complete ammonia oxidizers (comammox), oxidizing ammonia to nitrate directly, have been found to exist widely in multiple environments, but their distribution patterns are still under-explored in Antarctic environments. For the first time, the sediments were collected from West Antarctic lakes to investigate distribution patterns and community structure for comammox, ammonia oxidizing archaea (AOA) and bacteria (AOB), and nitrite-oxidizing bacteria (NOB), as well as the associations between ammonia oxidizers and antibiotic resistance genes (ARGs). Comammox clade B and AOB were dominant ammonia oxidizers, with the abundances of (1.62 ± 0.10) × 10² - (5.21 ± 0.74) × 10⁶ and (0.17 ± 0.05) × 10⁵ - (4.79 ± 0.65) × 10⁵ copies g^- 1 sediment, respectively. Comammox clade B, instead of clade A, occurred in all sediments, exhibiting higher abundances than AOB and AOA in most of the sediments. The abundances for comammox clade B demonstrated significant positive correlation (p < 0.01) with NH₄⁺-N levels, but negative correlation (p < 0.05) with C: N ratios. The coexistence of ammonia oxidizers in lake sediments was jointly structured by niche differentiation and environmental variables, and pH, modulated by penguin guano input, was found to be the most crucial factor in shaping their community structure. Co-occurrence network analyses revealed strong synergistic interactions between comammox and AOB, AOA, NOB, which played a critical role in nitrification processes. Our results further confirmed that comammox could act as important hosts for ARGs, hence stimulated their transmission and proliferation in the sediments. This study presented novel insights into the distribution patterns for ammonia oxidizers, their niche differentiation and the associations with ARGs in natural lake sediments of West Antarctica.

Phyllosphere microorganisms play a vital role in supporting host plant health and adaptability. Although previous research on the effects of host performance and their phylogenetic associations on phyllosphere microbial communities has predominantly focused on tropical, subtropical, and temperate forestry ecosystems, the responses of these microbial communities to plant phylogeny and functional traits in temperate desert environments remains poorly understood. In this study, we conducted a quantitative analysis of bacterial and fungal community structures in the phyllosphere of 39 plant species from the Gurbantunggut Desert, a typical temperate desert in Central Asia. Variation partitioning analysis revealed that plant phylogeny, leaf physicochemical properties, and leaf morphological characteristics collectively explained the variation in phyllosphere microbial communities. Specifically, these factors accounted for 19.26%, 14.53%, and 2.32% of the variance in bacterial communities, and 11.55%, 8.36%, and 2.19% of the variance in fungal communities, respectively. A significant hierarchical pattern emerged: plant phylogeny > leaf physicochemical properties > leaf morphological characteristics, highlighting the dominant role of plant filtering effects in community assembly. Linear mixed-effects model analysis further confirmed the significant influence of multiple plant attributes, including phylogeny and functional traits, on microbial community structure. Plant-microbe interaction analysis revealed distinct host preferences of microbial taxa across different plant taxonomic levels. Co-evolutionary analysis also indicated a significant phylogenetic association between host plants and their phyllosphere amplicon sequence variants (ASVs). Overall, our findings demonstrate that plant attributes, particularly plant phylogeny and functional traits, are key factors driving the assembly of phyllosphere microbial communities in deserts. This study provides new insights into species coexistence mechanisms in fragile habitats and enhances our understanding of plant-microbe interactions in global desert ecosystem.

Intercropping is a prevalent soil management strategy within walnut orchards, while its impacts on the functionality of arbuscular mycorrhizal fungi (AMF) in walnuts (Juglans regia) remain unclear, especially concerning soil carbon (C) sequestration via glomalin-related soil protein (GRSP). This study aimed to explore the effects of inoculation with the AMF species Diversispora spurca and intercropping with hairy vetch (Vicia villosa) on walnut biomass accumulation, soil water-stable aggregate (WSA) stability, leaf and root C (C_leaf and C_root) content, soil organic carbon (SOC), GRSP, and GRSP-contained C (C_GRSP), in addition to the contribution rate of C_GRSP to SOC. The intercropping treatment significantly inhibited root mycorrhizal colonization rate, soil hyphal length, and spore density in AMF-inoculated walnut plants. Individual AMF inoculation, rather than individual intercropping, significantly promoted shoot and root biomass accumulation, WSA stability, SOC, C_leaf and C_root, the levels of purified easily extractable (EEG), difficultly extractable (DEG), and total GRSP (TG), as well as their C contents. The combination treatment (AMF inoculation + intercropping) displayed limited benefits, improving just WSA stability without yielding synergistic advantages over individual treatments. Arbuscular mycorrhizal fungal inoculation significantly increased C_GRSP, especially C_DEG, while individual intercropping resulted in a reduction of C_DEG. The combination treatment elevated both C_DEG and C_TG, albeit to a lesser extent than AMF alone. The contribution rates of C_EEG, C_DEG, and C_TG to SOC were 0.33% - 0.53%, 1.16% - 1.78%, and 1.49% - 2.31%, respectively. Although AMF inoculation significantly increased the contribution rates of C_DEG and C_TG to SOC, this effect was diminished when combined with intercropping. Notably, C_DEG, rather than C_EEG, exhibited a significantly positive correlation with SOC and WSA stability. The findings provide new insights into the mechanisms of SOC sequestration in walnuts grown in controlled environments and offer a theoretical basis for the application of AMF in walnut cultivation.

The rapid expansion of tunnel engineering in China has led to extensive excavation of gravelly soils, resulting in significant land occupation that threatens the ecological environment and surrounding biota. As a result, there is an increasing need for effective ecological restoration of nutrient-poor gravelly soils, where challenges in vegetation establishment and sustainable soil management persist. This study evaluates the potential of Bacillus subtilis to promote the growth of Festuca arundinacea in engineered gravel soils through a controlled greenhouse experiment, examining its effects on plant growth, soil nutrient dynamics, and microbial community structure. The results showed that, compared to the control group (CK), neither the Bacillus subtilis treatment group (Bs) nor the nutrient application treatment group (LB) significantly altered the soil bacterial species composition at the phylum level. However, at the genus level, Azotobacter dominated the LB group, while Sphingomonas was the predominant genus in both the CK and Bs groups. Additionally, Bacillus subtilis significantly increased bacterial diversity relative to the nutrient application treatment, leading to substantial changes in microbial community composition. Furthermore, Bacillus subtilis notably enhanced both aboveground and belowground biomass, improved nutrient uptake, and increased the availability of phosphorus and potassium. It also stimulated soil enzymatic activities involved in carbon, nitrogen, and phosphorus cycling, emphasizing its critical role in nutrient cycling. Thus, Bacillus subtilis-driven soil enhancement offers a promising solution for ecological restoration in nutrient-poor gravelly soils, where conventional amendments are often ineffective. These findings underscore the potential of microbial-plant synergies to improve soil fertility and support sustainable vegetation restoration.

Acid mine drainage (AMD) generated during coal mining activities is characterized by low pH, high concentrations of dissolved metals and metalloids, and elevated sulfate levels, all of which significantly impact surrounding ecosystems. Scaling up biochemical passive reactor (BPR) systems represents a promising approach for the in situ bioremediation of AMD. While numerous laboratory-scale studies have described the taxonomic and functional composition of microbial communities in BPRs, typically dominated by (ligno)cellulolytic organisms and sulfate-reducing bacteria (SRB), it remains unclear whether this composition is maintained at the field-pilot scale under environmental conditions. To address this gap, 16S rRNA gene metabarcoding and shotgun metagenomics analyses were performed to characterize the taxonomic and functional diversity of microbial communities in the BPRs within a multi-unit field-pilot system. The results revealed that bioremediation effectiveness was driven by syntrophic interactions among hydrolytic, fermentative, and sulfate-reducing bacteria, aligning with laboratory-scale observations. While community composition shifts altered specific taxa, core operational dynamics remained preserved.

Soil fatigue, well documented in various crops, presents a significant challenge to banana production by causing fast and then gradual declines in plant growth and yield over years of cultivation. Despite its impact on profitability, the underlying mechanisms driving soil fatigue remain poorly understood; however, a strong link to shifts in the soil microbiome has been suggested. We investigated the dynamics of microbial communities in relation to soil fatigue, using a novel semi-controlled outdoor experimental system. Soil at different stages of fatigue (0 to 42 months of banana cultivation) was generated in large containers filled with initially healthy soil. Banana plants grown in these soils were replaced with new plants which showed soil age-dependent growth. Three months postplanting, soil and root samples were collected for analyses of soil parameters and microbial community composition using bacterial (16S) and fungal (ITS) amplicon sequencing. We identified minor age-related shifts in mainly pH, potassium, and organic matter in the soil. While alpha diversity remained unchanged, significant shifts in bacterial and fungal community composition were observed in fatigued soils. Notably, the relative abundance of bacterial families such as Flavobacteriaceae, Pseudomonaceae, and Acidibacter increased, as did some fungal taxa (many from groups with known pathogens)-Ceratobasidiaceae (including Rhizoctonia), Dothideomycetes, and Stachybotryaceae. Simultaneously, the relative abundance of bacterial families with known beneficial members, including Gemmatimonadaceae, Moraxellaceae, Sphingomonadaceae, and Azospirillaceae, as well as symbiotic fungal taxa such as Glomeraceae and Lasiosphaeriaceae, declined. Thus, soil fatigue may be correlated to the proliferation of pathogenic populations and a loss of beneficial microorganisms.

Antibiotic resistance genes (ARGs) accumulate in aquatic environments, where they create reservoirs and transmission pathways that can undermine antimicrobial treatments and alter the microbial community structure in ways that ultimately affect human and animal health. However, the contribution of zooplankton in these pathways remains critically overlooked. Emerging evidence shows that compared with surrounding water, copepods and cladocerans accumulate ARG loads that are one to two orders of magnitude greater, acting as microbial hotspots that disperse resistant bacteria across seasons and depths. Inside protistan vacuoles, densely packed prey cells undergo conjugation, rapidly accelerating horizontal ARG transfer. Long-term archives reveal persistent ocean-wide dissemination of the class-1 integron integrase (intI1) and sul2 genes since at least the 1970s. Here, I synthesize mechanistic and field evidence, pinpoint knowledge gaps, and recommend priorities: integrate zooplankton into routine ARG surveillance, quantify biofilm-mediated exchanges, and mitigate contamination from coselective pollutants to curb zooplankton-driven ARG propagation. By framing zooplankton-associated ARG dynamics within the broader community ecology of antimicrobial resistance, this mini-review highlights how aquatic food-web processes feed back into the emergence, evolution, and transmission of resistance that concerns for One Health outcomes beyond the clinic.