Microbial Ecology最新文献

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.

Soil microbiomes, critical for plant productivity and ecosystem functioning, mediate essential functions such as pathogenesis, mutualism, and decomposition through different fungal functional groups. Yet, our understanding of the dynamics of co-existing soil fungal functional groups in the rhizosphere remains limited. By leveraging urban farming-featuring fields of different ages and multiple genotypes-we tracked the relative abundance, richness, and microbial networks of putative plant pathogenic fungi, mycorrhizal fungi, and saprotrophic fungi across fields over two years. We observed an increase in the relative abundance of putative plant pathogenic fungi in the rhizosphere in older fields relative to younger fields, supporting the prediction of pathogen accumulation over time. In contrast, there was a decrease in the relative abundance of mycorrhizal fungi in older fields. The relative abundance of saprotrophic fungi remained similar between younger and older fields. While the richness of putative plant pathogenic fungi and saprotrophic fungi was similar across the examined fields, the community structure of both groups differed between younger and older fields. For mycorrhizal fungi, the richness declined in older fields and over the two years. These dynamics led to distinct microbial networks, with decreased network links for mycorrhizal fungi and increased links for saprotrophic fungi in older fields, whereas the links for plant pathogenic fungi remained similar across fields. Our study reveals contrasting dynamics of essential soil fungal functional groups in the rhizosphere and provides predictive insight into the potential shifts in soil function and their impact on plant productivity.

Species traits and environmental conditions are among the many factors that shape bee communities. Their effective conservation is currently challenged due to global changes. The gut microbiome likely contributes to bee plasticity and resilience but is largely understudied in solitary bees. A stable core microbiome in social bees has been identified to be important for health and survival in changing environmental conditions, but knowledge on a host-specific core microbiome in solitary bees is very scarce. In the present study, we analyzed the gut bacterial and fungal communities of eight solitary bee species commonly found in apple orchards along a latitudinal gradient throughout Europe. We aimed to understand the intra- and interspecific variations in the gut microbial communities and the extent to which host species and local environment shape the solitary bee gut microbiota. The bacterial community showed strong host effects, with each bee species having a distinct core bacterial community that was mostly stable across locations. The fungal community was most strongly influenced by the local environment, while different environmental variables were responsible for the variation in bacterial and fungal communities. Our study demonstrated that the examined solitary bee species harbor a distinct microbial diversity and composition, which undergoes host- and location-specific filtering.

Bamboo plays a crucial role in mitigating climate change. Among various microorganisms inhabiting bamboo, Apiospora is a common bambusicolous fungus that induces black spots, functioning either as a saprobe or as a plant pathogen. However, the diversity and ecological roles of Apiospora as an endophyte in bamboo remain poorly understood. This study explored the diversity and ecological functions of bambusicolous Apiospora in Phyllostachys bambusoides forests. Bamboo samples representing different stages-young (1-year-old, without black spots), mature (aged 3 years, few black spots), and dead (with many black spots)-were collected. Mycobiome analyses across different tissues (culm, leaf, root) and environmental samples (forest soil) revealed diverse Apiospora species throughout the bamboo lifecycle. Notably, Apiospora hysterina emerged as a prevalent endophyte, inhabiting not only mature but also younger, healthier bamboo stages. Biological activity assays, including antioxidant, antifungal, and plant hormone tests, indicated that A. hysterina exhibits potential mutualistic interactions beneficial to bamboo. Conversely, genomic analyses of carbohydrate-active enzyme profiles, effector/virulence factors, and putative biosynthetic gene clusters suggested potential pathogenic capabilities that may involve secondary metabolites, though functional validation is required. These findings reveal the widespread presence of Apiospora species as endophytes from the early to senescent bamboo stages, highlighting A. hysterina's dual capacity as a symbiont and pathogen. Our study underscores the complexity of bambusicolous Apiospora's ecological roles, emphasizing the need for further investigation into its interactions with bamboo ecosystems.

Acinetobacter calcoaceticus, a ubiquitous Gram-negative bacterium, exhibits remarkable adaptability across diverse environments, including drinking water distribution systems (DWDS), where its biofilm-forming and coaggregation capabilities pose significant public health challenges. This study integrates physicochemical, structural, and proteomic analyses to elucidate the mechanisms underlying A. calcoaceticus aggregation and biofilm dynamics. Surface characterization through contact angle measurements, zeta potential, and co-adhesion energy assessments revealed a predominantly hydrophilic surface with strong electron donor properties and a highly negative charge, promoting intercellular adhesion. Transmission electron microscopy unveiled dense cellular aggregates with extracellular filamentous structures, indicative of enhanced cell-to-cell interactions and potential extracellular polymeric substance involvement. Proteomic profiling identified 2593 differentially expressed proteins between aggregation stages, highlighting metabolic shifts, stress response activation, and upregulation of biofilm-associated proteins, including chaperones and quorum-sensing regulators. Our multidisciplinary approach emphasizes the importance of surface characterization in understanding bacterial community and underscores the critical role of physicochemical properties and proteomic flexibility in A. calcoaceticus biofilm and aggregation ability.

Facility cultivation systems provide protection for jujube (Ziziphus jujuba) against rain-induced fruit cracking during the maturation and regulate the fruit ripening process. Prolonged cultivation within these controlled environments may alter the soil microbial community structure, potentially detrimentally affecting plant growth and fruit quality. There is a lack of information regarding the arbuscular mycorrhizal fungi (AMF) and bacterial communities in orchards under facility conditions. This study compared the soil bacterial and AMF communities in jujube orchards under greenhouse and rain shelter conditions. Greenhouse cultivation significantly increased soil organic carbon (SOC), total nitrogen (TN), and electrical conductivity, while it decreased soil pH compared to rain shelters. These changes were associated with reduced α-diversity indices in both bacterial and AMF communities. Non-metric multidimensional scaling analysis demonstrated distinct differences between bacteria and AMF communities under the two cultivation types. The phyla Actinobacteria, Gemmatimonadetes, and Rokubacteria were identified as key contributors to the observed alterations in the bacterial community, while variations in the genus Glomus and Paraglomus were responsible for changes in the AMF communities between the two cultivation types. Redundancy analysis revealed that pH was the primary factor shaping microbial community structure across the two cultivation types. Using a Zi-Pi plot, we identified several keystone ASVs, which showed a positive correlation with pH, SOC, and TN. The findings highlight the significant impact of cultivation type on soil microbial community structure and function, which has important implications for optimizing cultivation practices and ensuring sustainable jujube production.

The species that make up a microbial community determine its potential function. A major goal of microbial ecology is to make assemblages of microbes - synthetic communities - with targeted applications. Replacing a dysfunctional community with a synthetic microbial community can have transformative impacts upon a host or ecosystem, yet the introduced community may be outcompeted by local species or communities, resulting in transient effects. Here, we study a simple synthetic community comprised of two species - E. coli and S. cerevisiae - that have coevolved for either 0, 1000 or 4000 generations, and evaluate the potential for 12 bacterial strains, from five species, to invade. We find that the dominant species (E. coli) in the community protects the less dominant species from being outcompeted during an invasion, and that this effect is strengthened by longer periods of coevolution. Using a mathematical model, we show how prolonged co-evolution leads to protective effects for a community member sensitive to displacement.

One underexplored aspect of microbial growth is the impact of toxic gases transported through the atmosphere. Ammonia is a gas that can supply essential nitrogen but also exert cellular toxicity. Ammonia volatilized from a concentrated source into surrounding environments is therefore a crucial consideration when assessing the capacity of environments to support life, such as within terrestrial environments polluted with ammonia, or the ice crusts above ammonia-water oceans of icy moons. We cultivate Halomonas meridiana proximal to an ammonia source and examine the impact of ammonia volatilization on growth. Lower cell densities (OD₆₀₀ = 0-1) occurred nearest the ammonia source. At 24 h, wells exhibiting an OD₆₀₀ = 0-0.5 were evident when ammonia concentrations were ≥ 0.5 M. H. meridiana in proximity to 0 M, 0.1 M, 0.25 M, 0.5 M, and 1 M ammonia exhibited OD₆₀₀ > 2 in 89.86%, 57.97%, 37.32%, 30.07%, and 18.48% of culture wells at 48 h, respectively. Alteration to growth kinetics and viability of H. meridiana cultivated adjacently to an ammonia source ("adjacently exposed") were not as severe compared to direct culture in ammonia ("directly exposed"). Compared to control, adjacent exposure to 0.1 M ammonia exerted no significant detrimental effect on growth kinetics and enhanced cell density, but adjacent exposure to ≥ 0.5 M ammonia greatly extended lag time, doubling time, reduced cell density, and reduced viability. Ammonia volatilized from 0.1 M sources may thus minimally affect, if not improve, habitability, whereas environments exposed to ammonia volatilized from sources at ≥ 0.5 M could constrain habitability.

Rice-associated leafhoppers (Cicadellidae) play a significant role in rice agroecosystems, contributing not only to direct crop damage but also to the transmission of plant pathogens. This study investigates the symbiont diversity of seventeen leafhopper species from the tropical floodplains of Tonle Sap Lake (TSL), Cambodia. The dominant symbiont across most species was Candidatus (Ca.) Karelsulcia muelleri, an obligate primary endosymbiont essential for nutrient synthesis. The co-obligate symbiont Ca. Nasuia deltocephalinicola was also consistently detected, particularly in Deltocephalinae hosts. In addition, several secondary symbionts, including Sodalis, Arsenophonus, Diplorickettsia, Rickettsia, Wolbachia, and Ca. Lariskella, were identified, showing species-specific associations and potential roles in host fitness and pathogen transmission. Variations in symbiont diversity were observed across cicadellid species, geographic origins, and between sex-associated symbionts, with notable differences in the bacterial composition of Nephotettix virescens. While geographical differences (Battambang vs. Kampong Thom) did not strongly affect microbial composition, sex-associated variations were evident in N. virescens. Females exhibited a higher abundance of Karelsulcia and Nasuia, suggesting possible microbial adaptation related to reproduction. This study highlights the complex and dynamic nature of cicadellid hosts-symbiont interactions and suggests that microbial communities are primarily structured by host species. While geographic distance can influence these communities, this effect is not the same for every species. These findings provide critical insights into the microbial diversity of rice-associated leafhoppers and their potential for ecological roles in rice farming systems. Further studies, including functional analysis and host-symbiont interactions, are crucial to understanding the ecological roles and evolutionary dynamics of these microbial communities.