Microbial Ecology最新文献

Freshwater ecosystems within protected areas play a vital role in maintaining biodiversity and ecological stability, yet they are increasingly threatened by anthropogenic disturbances such as agriculture and tourism. Understanding the impacts of human activities on water quality and microbial community dynamics is essential for the effective conservation and management. This study investigates the spatial variability of water quality and microbial communities across the core, buffer, and experimental zones of the Heilongjiang Maolan Gou National Nature Reserve. Twelve water samples were collected and analyzed for key physicochemical parameters (turbidity, electrical conductivity (EC), chemical oxygen demand (COD), biochemical oxygen demand (BOD), NH₄⁺, PO₄³⁻ and heavy metals). The core zone exhibited excellent water quality with low turbidity (0.4-0.5 NTU), EC (45-130 µS/cm), COD (8-10 mg/L), BOD (1.5-2.2 mg/L). In contrast, the experimental zone showed significant contamination due to agriculture and tourism, with high COD (up to 35 mg/L), BOD (up to 6.5 mg/L), NH₄⁺ (0.18-0.35 mg/L), and PO₄^3- (0.008-0.035 mg/L). Heavy metal concentrations, particularly Cd (up to 0.24 µg/L), were elevated in the experimental zone, correlating with higher Pollution and Water Quality Indices (HPI up to 96.4, WQI up to 61.28). According to standard classifications, HPI values > 100 indicated heavy pollution and WQI scores between 50 and 100 denoted moderate to poor water quality, highlighting degraded conditions in the experimental zone. Microbial analysis revealed distinct community structures across zones, with enhanced pollutant-degrading taxa such as Pseudomonas (noted for aromatic hydrocarbon degradation) and members of Bacteroidota (associated with organic matter breakdown) in the experimental zone. These findings highlight the need for sustainable management to mitigate human impacts and preserve ecological health within the reserve.

Akkermansia muciniphila is a specialist mucin glycan-degrader that is common in the human gut. A. muciniphila is associated with host health and therefore proposed as a next-generation probiotic. However, it is unknown if consumption of live and active A. muciniphila will be effective in terms of survival and engraftment in the gut microbiome. Furthermore, it is of interest whether introduction of A. muciniphila would influence the resident mucosal microbiota. To this end, we investigate the addition of live A. muciniphila to a stable in vitro microbial mucin glycan-degrading synthetic community. A. muciniphila engrafted in this synthetic community and actively degraded mucin using essential mucin glycan-degrading enzymes. Addition of A. muciniphila did not induce major compositional changes, except that Bacteroides thetaiotaomicron increased in relative abundance at the expense of Bacteroides caccae. At the metaproteomic level, community function was not significantly affected, as peptidase, fucosidase, galactosidase and sulfatase expression remained stable. However, sialidase was significantly enriched after A. muciniphila addition, which can be explained by the relative increase of generalist glycan-degrader B. thetaiotaomicron. Overall, we show that a community without A. muciniphila still harbours a niche for this bacterium, but that A. muciniphila did not induce major changes in the in vitro mucosal synthetic community. This suggests that A. muciniphila applied as a probiotic can engraft and exert its beneficial effects on the host, without major impact on the human gut mucosal microbiota composition and function and warrants further research into A. muciniphila engraftment in vivo.

Dutch elm disease (DED) has caused devastating pandemics in natural elm populations across Europe, North America, and Asia. The primary vectors of DED are native elm-associated bark beetles of the genus Scolytus. However, there is evidence suggesting that ambrosia beetles may also carry Ophiostoma novo-ulmi and potentially transmit it to elm trees. In this study, we explored microbial interactions and host selection mechanisms that could support the role of ambrosia beetles as vectors of O. novo-ulmi. Our study showed that females of Anisandrus dispar, Xyleborinus saxesenii, Xylosandrus crassiusculus, and Xylosandrus germanus emerging from both DED-infected and healthy elm logs carried O. novo-ulmi DNA. Furthermore, we showed that none of the tested ambrosia beetle fungal symbionts was adversely affected by O. novo-ulmi, while Dryadomyces spp. and the bacterial symbiont Erwinia sp. 1C4 partially restricted or inhibited O. novo-ulmi growth without fully suppressing it. Overall, these findings provide additional evidence supporting the potential role of ambrosia beetles as vectors of DED and emphasize the need for further research on this understudied insect-pathogen relationship.

This study investigates the adaptive response of streambed microbial biofilms to water scarcity, focusing on the role of extracellular polymeric substances (EPS) production across a gradient of hydrological conditions. Sediment samples from 37 streams in the north-eastern Iberian Peninsula, encompassing both permanent and intermittent flow regimes, were analysed for EPS-polysaccharide content, microbial biomass, chlorophyll-a, and biofilm function (carbon substrate utilization profiles). Drought conditions were characterized based on the number of dry days over the eight months preceding sampling. Results revealed that EPS production increased significantly in intermittent streams, particularly under long-term drought, reaffirming that EPS synthesis is a key microbial strategy to mitigate desiccation stress. Notably, when normalized to prokaryotic density, EPS content exhibited a significant positive correlation with drought duration, emphasizing the dominant role of heterotrophic bacteria over algae in EPS secretion. However, EPS content alone was not a universal indicator of water scarcity, which showed a large variability in permanently flowing streams. Functional profiling showed clear shifts in carbon substrate utilization associated with stream hydrology. Intermittent streams exhibited a broader metabolic range, and particularly a capacity to use phenolic compounds, suggesting an adaptation to terrestrial organic matter inputs. Contrary to expectations, functional diversity increased in drier conditions, challenging assumptions derived from controlled experiments and underscoring the resilience of Mediterranean microbial biofilm communities to drought. These findings provide empirical support for EPS-mediated drought adaptation in natural biofilms and highlight functional diversity as a potential mechanism maintaining ecosystem processes under increasing aridity due to climate change.

Sour rot is a complex disease of grapes, primarily caused by the synergistic effects of yeast and Drosophila species, leading to fruit decay, poor quality, and significant economic losses. The lack of information on species distribution and diversity of these organisms in China limits the efficacy of control strategies. In this study, we sequenced the 26S rRNA D1/D2 region in yeasts and the COI region in Drosophila. Nine yeast genera were identified. Hanseniaspora spp. (45.76% of total) were the most abundant, followed by Starmerella spp. (23.62%) and Saccharomyces spp. (17.34%). At the species level, 14 yeast species were identified. Starmerella bacillaris (23.62%), Saccharomyces cerevisiae (17.34%), H. opuntiae (17.34%), and H. uvarum (15.13%) predominated. Of the five species of Drosophila present, Drosophila melanogaster (63.16%) was the dominant species. This study is the first to characterize the diversity of yeasts and Drosophila across major grape-producing regions in China. The findings provide a scientific foundation for elucidating the key drivers of sour rot and designing targeted control strategies.

Microorganisms play a significant role in improving the flavor and quality of plant products. Analyzing how tobacco processing affects the microbial community structure is essential. Understanding the synergistic mechanisms of microorganisms during this process can help optimize the flavor and quality of plant products. In this study, samples were collected from four processing stages (T1: fresh leaves, T2: 42 °C, T3: 54 °C, T4: 68 °C), and metabolite and Phylloplane microbial data of tobacco leaves were generated. A comprehensive multi-omics analysis was conducted. The study shows that the increase in temperature and the decrease in humidity during the processing lead to the reorganization of the microbial community. Brevibacterium, Staphylococcus, Aspergillus, and Ganoderma were identified as core biomarkers. Bacteria dominate in the initial degradation of starch, while fungi promote the accumulation of soluble sugars through the transformation of intermediate products. This study deepens our understanding of the role of microorganisms and their carbohydrate metabolism in the tobacco leaf processing process and proposes a new strategy for constructing regulatory models by integrating multi-omics.

This study investigates the ecological mechanisms governing the structure and composition of lung microbiome communities within tumor tissue from lung cancer patients. While this field has attracted increasing research attention, the ecological and etiological mechanisms driving microbial community assembly in this environment remain poorly characterized. To address this gap, we applied Sloan's near neutral model, Ning et al.'s normalized stochasticity ratio framework and Harris et al.'s multi-site neutral model to evaluate the influences of stochastic and deterministic factors at species, community and metacommunity levels, respectively. Our findings include: (i) Stochastic drift exhibited predominant influence at both species and community levels in normal adjacent tissue (NT), exceeding its effects in LUAD (lung adenocarcinoma) and LUSC (lung squamous cell carcinoma). (ii) At the metacommunity level, neutrality was not rejected at the metacommunity or local community levels, which is consistent with the previous finding (i). (iii) Elevated metacommunity biodiversity (θ) and immigration rates (m) in LUAD/LUSC compared to NT (observed in ∼50% of cases) suggest that tumor occurrence/progression may actively promote microbial recruitment to tumor microenvironments. We propose three non-exclusive mechanistic interpretations: (i) Tumor-mediated immune modulation creates permissive ecological niches; (ii) structural remodeling of tissue enhances microbial colonization potential; (iii) selective enrichment of opportunistic taxa (e.g., Streptococcus) through tumor-specific microenvironmental changes. Our results demonstrate that LUAD and LUSC microbiomes are shaped by deterministic tumor-driven selection, in contrast to the predominantly stochastic assembly observed in NT microbiomes. These findings reveal substantial reorganization of tumor-associated microbial communities, warranting further biomedical investigation and clinical validation.

Black rot disease (BRD), caused by the still understudied Phyllosticta ampelicida, is spreading across several grape producing countries, posing a growing threat to the agroindustry. The role of the grapevine microbiome in defending against this pathogen, particularly in terms of microbiota structure and community homeostasis, remains unclear. In this study, we aimed to characterize the epiphytic phyllosphere microbiota of grapevines and identify shifts in microbial genetic structure associated with BRD symptoms. We sampled three vineyards of the cultivar "Touriga Nacional" in the Douro region (Portugal), collecting 20 leaves from (a) five healthy and (b) five BRD-symptomatic grapevines. The presence of P. ampelicida was confirmed in all symptomatic samples. Epiphytic bacterial DNA was extracted and sequenced using next-generation sequencing (NGS). Results indicate that although overall the diversity and richness indexes were not different in diseased plants compared to healthy ones, there was a reduction in OTU richness in black rot-affected grapevines. Diseased plants exhibited significant shifts in microbial network assemblages and showed an increased relative abundance of certain taxa, such as Acinetobacter, suggesting a possible recruitment of beneficial bacteria in response to biotic stress. Additionally, we observed a higher abundance of antibiotic resistance-related KEGG Orthologues (KOS) in symptomatic plants, raising potential concerns for human health. This study presents the first characterization of the grapevine phyllosphere epiphytic bacterial microbiota and its structural shifts in response to BRD.

Ticks are important vectors of pathogens affecting livestock productivity and public health, yet their bacterial communities remain poorly characterized in many parts of South Africa. This study investigated the bacterial diversity and potential pathogenic bacterial etiology associated with Amblyomma hebraeum ticks collected from sheep and goats in Mahikeng, North West province. A total of 168 adult ticks were sampled across four villages. Microbiome profiling was performed using high-throughput sequencing of the V3-V4 hypervariable regions of the 16S rRNA gene on the Illumina MiSeq platform. High-throughput 16S rRNA sequencing revealed 16,193 ASVs in goat-derived ticks and 16,510 ASVs in those from sheep. Proteobacteria emerged as the dominant phylum across all samples, with ticks collected from goats showing a particularly high dominance of Rickettsia spp. (51.64% relative abundance), suggesting potential zoonotic risks. In contrast, ticks from sheep harboured significantly more diverse and evenly distributed bacterial communities, as indicated by Shannon (p = 0.0138) and Simpson (p = 0.0233) diversity indices, despite comparable species richness. A core microbiome comprising 1,374 ASVs (32.3%) was shared across all ticks, alongside 1,504 and 1,372 unique ASVs in goat- and sheep-derived ticks, respectively. Notably, several medically and veterinary-relevant genera, including Coxiella, Ehrlichia, Staphylococcus, Bacillus, Acinetobacter, Corynebacterium, and Streptococcus, were detected across both host groups. While total species richness was comparable between hosts, alpha diversity indices that account for evenness revealed host-based differences, and beta diversity patterns further showed clear separation of bacterial communities by host species. This study indicates that the host plays a crucial role as an ecological driver affecting the diversity of microbial communities associated with ticks. This study improves our understanding of the diversity, composition, and abundance of tick-associated microbiomes and pathogens in South African small ruminants. These insights support the development of microbiome-targeted strategies for detecting and controlling tick-borne diseases.

Marine heatwaves affect the abundance and community structure of microbial plankton, with implications for food web and ecosystem processes, but their impact on microbially mediated elemental cycling remains poorly constrained. To determine the biogeochemical effects of increased temperature, we conducted an experiment in September 2023 in which a plankton community from a coastal, productive ecosystem (Ría de Vigo, NW Iberia) was exposed to a warming of + 2 °C and + 4 °C under unamended and nutrient-enriched conditions. The response of microbial plankton was characterized in terms of organic matter production, carbon fixation, nitrogen uptake, and oxygen net production. We found that warming caused increased nutrient consumption and biomass production, as well as faster bloom dynamics, both in unamended and nutrient-enriched treatments, indicating that the community was robust to thermal perturbation. Accelerated nutrient depletion under warming gave way to an earlier decrease in carbon fixation and nitrate uptake rates, together with a shift towards a negative or less positive metabolic balance. Carbon fixation was less sensitive than nitrate uptake to the different temperature and nutrient scenarios, leading to wide changes in the carbon-to-nitrogen uptake ratio, while respiration increased non-linearly with temperature. Overall, the investigated microbial fluxes were more responsive to nutrient availability than to temperature. Our results show that microbially driven ecosystem services in coastal waters have the potential to be enhanced during short-term warming events.