Environmental Microbiome

Mycorrhizal and endophytic fungi structure forest below-ground symbiosis through contrasting but interdependent assembly processes
Noguchi M and Toju H
Interactions between plants and diverse root-associated fungi are essential drivers of forest ecosystem dynamics. The symbiosis is potentially dependent on multiple ecological factors/processes such as host/symbiont specificity, background soil microbiome, inter-root dispersal of symbionts, and fungus-fungus interactions within roots. Nonetheless, it has remained a major challenge to reveal the mechanisms by which those multiple factors/processes determine the assembly of root-associated fungal communities. Based on the framework of joint species distribution modeling, we examined 1,615 root-tips samples collected in a cool-temperate forest to reveal how root-associated fungal community structure was collectively formed through filtering by host plants, associations with background soil fungi, spatial autocorrelation, and symbiont-symbiont interactions. In addition, to detect fungi that drive the assembly of the entire root-associated fungal community, we inferred networks of direct fungus-fungus associations by a statistical modeling that could account for implicit environmental effects.
Plant growth-promoting fungi improve tobacco yield and chemical components by reassembling rhizosphere fungal microbiome and recruiting probiotic taxa
Shi M, Hao S, Wang Y, Zhang S, Cui G, Zhang B, Zhou W, Chen H and Wang M
Tobacco production faces ongoing challenges due to soil degradation, leading to a persistent decline in yield. Plant growth-promoting fungi (PGPF) have been recognized as an environmentally friendly agricultural strategy. However, many commercial PGPF products exhibit instability due to insufficient environmental compatibility.
Soil P-stimulating bacterial communities: response and effect assessment of long-term fertilizer and rhizobium inoculant application
Wei W, Ma M, Jiang X, Meng F, Cao F, Chen H, Guan D, Li L and Li J
Phosphorus (P) plays a vital role in plant growth. The pqqC and phoD genes serve as molecular markers for inorganic and organic P breakdown, respectively. However, the understanding of how P-mobilizing bacteria in soil respond to long-term fertilization and rhizobium application is limited. Herein, soil that had been treated with fertilizer and rhizobium for 10 years was collected to investigate the characteristics of P-mobilizing bacterial communities. Five treatments were included: no fertilization (CK), phosphorus fertilizer (P), urea + potassium fertilizer (NK), NPK, and PK + Bradyrhizobium japonicum 5821 (PK + R).
Stochasticity-dominated rare fungal endophytes contribute to coexistence stability and saponin accumulation in Panax species
Liu Y, Shi L, Hong F, Wei G, Jiang Z, Wei X, Peng J, Zhang G and Dong L
Fungal communities inhabiting plant tissues are complex systems of inter-species interactions, consisting of both the "abundant biosphere" and "rare biosphere". However, the composition, assembly, and stability of these subcommunities, as well as their contributions to productivity remain unclear. In this study, the taxonomic and functional composition, co-occurrence, and ecological assembly of abundant and rare fungal subcommunities in different tissues of three Panax species were investigated. Abundant subcommunities were dominated by potential plant pathogens belonging to Microbotryomycetes, while saprotrophic fungi like Agaricomycetes and Mortierellomycetes were more prevalent in rare subcommunities. The rare taxa played a central role in upholding the stability of the fungal networks as driven by Dothideomycetes and Sordariomycetes. Homogeneous selection played a larger role in the assembly of abundant fungal subcommunities compared to the rare counterparts, which was more dominated by stochastically ecological drift in all plant species. Rare biospheres played a larger role in the accumulation of saponin compared to their abundant counterparts, especially in the leaf endosphere, which was mainly affected by environmental factors (Mg, pH, OC, and etc.). Furthermore, we found that rare species belonging to unidentified saprotrophs were associated with saponin formation. This study provides hypotheses for future experiments to understand mechanisms accounting for the variations in the composition and function of rare fungal subcommunities across different Panax species.
MIMt: a curated 16S rRNA reference database with less redundancy and higher accuracy at species-level identification
Cabezas MP, Fonseca NA and Muñoz-Mérida A
Accurate determination and quantification of the taxonomic composition of microbial communities, especially at the species level, is one of the major issues in metagenomics. This is primarily due to the limitations of commonly used 16S rRNA reference databases, which either contain a lot of redundancy or a high percentage of sequences with missing taxonomic information. This may lead to erroneous identifications and, thus, to inaccurate conclusions regarding the ecological role and importance of those microorganisms in the ecosystem.
Biochar-induced changes in soil microbial communities: a comparison of two feedstocks and pyrolysis temperatures
Kracmarova-Farren M, Alexova E, Kodatova A, Mercl F, Szakova J, Tlustos P, Demnerova K and Stiborova H
The application of a biochar in agronomical soil offers a dual benefit of improving soil quality and sustainable waste recycling. However, utilizing new organic waste sources requires exploring the biochar's production conditions and application parameters. Woodchips (W) and bone-meat residues (BM) after mechanical deboning from a poultry slaughterhouse were subjected to pyrolysis at 300 °C and 500 °C and applied to cambisol and luvisol soils at ratios of 2% and 5% (w/w).
The role of the rhizobiome recruited by root exudates in plant disease resistance: current status and future directions
Feng Z, Liang Q, Yao Q, Bai Y and Zhu H
Root exudates serve as a bridge connecting plant roots and rhizosphere microbes, playing a key role in influencing the assembly and function of the rhizobiome. Recent studies have fully elucidated the role of root exudates in recruiting rhizosphere microbes to enhance plant performance, particularly in terms of plant resistance to soil-borne pathogens; however, it should be noted that the composition and amount of root exudates are primarily quantitative traits regulated by a large number of genes in plants. As a result, there are knowledge gaps in understanding the contribution of the rhizobiome to soil-borne plant disease resistance and the ternary link of plant genes, root exudates, and disease resistance-associated microbes. Advancements in technologies such as quantitative trait loci (QTL) mapping and genome-wide association studies (GWAS) offer opportunities for the identification of genes associated with quantitative traits. In the present review, we summarize recent studies on the interactions of plant and rhizosphere microbes through root exudates to enhance soil-borne plant disease resistance and also highlight methods for quantifying the contribution of the rhizobiome to plant disease resistance and identifying the genes responsible for recruiting disease resistance-associated microbes through root exudates.
Long-term garlic‒maize rotation maintains the stable garlic rhizosphere microecology
He S, Lv M, Wang R, Li N, Wang T, Shi W, Gao Z and Li X
Crop rotation is a sophisticated agricultural practice that can modify the demographic structure and abundance of microorganisms in the soil, stimulate the growth and proliferation of beneficial microorganisms, and inhibit the development of harmful microorganisms. The stability of the rhizosphere microbiome is crucial for maintaining both soil ecosystem vitality and crop prosperity. However, the effects of extended garlic‒maize rotation on the physicochemical characteristics of garlic rhizosphere soil and the stability of its microbiome remain unclear. To investigate this phenomenon, soil samples from the garlic rhizosphere were collected across four different lengths of rotation in a garlic-maize rotation.
Functional diversity of the above-ground fungal community under long-term integrated, organic and biodynamic Vineyard Management
Steng K, Roy F, Kellner H, Moll J, Tittmann S, Frotscher J and Döring J
Sustainable agriculture increasingly emphasizes the importance of microbial communities in influencing plant health and productivity. In viticulture, understanding the impact of management practices on fungal communities is critical, given their role in disease dynamics, grape and wine quality. This study investigates the effects of integrated, organic, and biodynamic management practices on the diversity and function of fungal communities in a vineyard located in Geisenheim, Germany, focusing on above-ground parts such as bark, leaves, and grapes.
Selenium alters the gene content but not the taxonomic composition of the soil microbiome
Bennett AE, Kelsey S, Saup C, Wilkins M and Malacrinò A
Microbiomes, essential to ecosystem processes, face strong selective forces that can drive rapid evolutionary adaptation. However, our understanding of evolutionary processes within natural systems remains limited. We investigated evolution in response to naturally occurring selenium in soils of different geological parental materials on the Western Slope of Colorado. Our study focused on examining changes in gene frequencies within microbial communities in response to selenium exposure.
Soil properties drive nitrous oxide accumulation patterns by shaping denitrifying bacteriomes
Bano S, Wu Q, Yu S, Wang X and Zhang X
In agroecosystems, nitrous oxide (N₂O) emissions are influenced by both microbiome composition and soil properties, yet the relative importance of these factors in determining differential N₂O emissions remains unclear. This study investigates the impacts of these factors on N₂O emissions using two primary agricultural soils from northern China: fluvo-aquic soil (FS) from the North China Plain and black soil (BS) from Northeast China, which exhibit significant differences in physicochemical properties. In non-sterilized controls (NSC), we observed distinct denitrifying bacterial phenotypes between FS and BS, with BS exhibiting significantly higher N₂O emissions. Cross-inoculation experiments were conducted by introducing extracted microbiomes into sterile recipient soils of both types to disentangle the relative contributions of soil properties and microbiomes on N₂O emission potential. The results showed recipient-soil-dependent gas kinetics, with significantly higher N₂O/(N₂O + N₂) ratios in BS compared to FS, regardless of the inoculum type. Metagenomic analysis further revealed significant shifts in denitrification genes and microbial diversity of the inoculated bacteriomes influenced by the recipient soil. The higher ratios of nirS/nosZ in FS and nirK/nosZ in BS indicated that the recipient soil dictates the formation of different denitrifying guilds. Specifically, the BS environment fosters nirK-based denitrifiers like Rhodanobacter, contributing to higher N₂O accumulation, while FS supports a diverse array of denitrifiers, including Pseudomonas and Stutzerimonas, associated with complete denitrification and lower N₂O emissions. This study underscores the critical role of soil properties in shaping microbial community dynamics and greenhouse gas emissions. These findings highlight the importance of considering soil physicochemical properties in managing agricultural practices to mitigate N₂O emissions.
Alpine and subalpine plant microbiome mediated plants adapt to the cold environment: A systematic review
Hou M, Leng C, Zhu J, Yang M, Yin Y, Xing Y and Chen J
With global climate change, ecosystems are affected, some of which are more vulnerable than others, such as alpine ecosystems. Microbes play an important role in environmental change in global ecosystems. Plants and microbes are tightly associated, and symbiotic or commensal microorganisms are crucial for plants to respond to stress, particularly for alpine plants. The current study of alpine and subalpine plant microbiome only stays at the community structure scale, but its ecological function and mechanism to help plants to adapt to the harsh environments have not received enough attention. Therefore, it is essential to systematically understand the structure, functions and mechanisms of the microbial community of alpine and subalpine plants, which will be helpful for the conservation of alpine and subalpine plants using synthetic microbial communities in the future. This review mainly summarizes the research progress of the alpine plant microbiome and its mediating mechanism of plant cold adaptation from the following three perspectives: (1) Microbiome community structure and their unique taxa of alpine and subalpine plants; (2) The role of alpine and subalpine plant microbiome in plant adaptation to cold stress; (3) Mechanisms by which the microbiome of alpine and subalpine plants promotes plant adaptation to low-temperature environments. Finally, we also discussed the future application of high-throughput technologies in the development of microbial communities for alpine and subalpine plants. The existing knowledge could improve our understanding of the important role of microbes in plant adaptation to harsh environments. In addition, perspective further studies on microbes' function confirmation and microbial manipulations in microbiome engineering were also discussed.
Parasitic taxa are key to the vertical stratification and community variation of pelagic ciliates from the surface to the abyssopelagic zone
Wan Y, Zhao F, Filker S, Hatmanti A, Zhao R and Xu K
An increase in upper-ocean thermal stratification is being observed worldwide due to global warming. However, how ocean stratification affects the vertical profile of plankton communities remains unclear. Understanding this is crucial for assessing the broader implications of ocean stratification. Pelagic ciliates cover multiple functional groups, and thus can serve as a model for studying the vertical distribution and functional strategies of plankton in stratified oceans. We hypothesize that pelagic ciliate communities exhibit vertical stratification caused by shifts in functional strategies, from free-living groups in the photic zone to parasitic groups in deeper waters.
Metatranscriptomics of microbial biofilm succession on HDPE foil: uncovering plastic-degrading potential in soil communities
MacLean J, Bartholomäus A, Blukis R, Liebner S and Wagner D
Although plastic pollution is increasing worldwide, very little is known about the microbial processes that take place once plastic debris is incorporated into the soil matrix. In this study, we conducted the first metatranscriptome analysis of polyethylene (PE)-associated biofilm communities in highly polluted landfill soil and compared their gene expression to that of a forest soil community within a 53-day period.
Cold-water coral mortality under ocean warming is associated with pathogenic bacteria
Chemel M, Peru E, Binsarhan M, Logares R, Lartaud F and Galand PE
Cold-water corals form vast reefs that are highly valuable habitats for diverse deep-sea communities. However, as the deep ocean is warming, it is essential to assess the resilience of cold-water corals to future conditions. The effects of elevated temperatures on the cold-water coral Lophelia pertusa (now named Desmophyllum pertusum) from the north-east Atlantic Ocean were experimentally investigated at the holobiont level, the coral host, and its microbiome. We show that at temperature increases of + 3 and + 5 °C, L. pertusa exhibits significant mortality concomitant with changes in its microbiome composition. In addition, a metagenomic approach revealed the presence of gene markers for bacterial virulence factors suggesting that coral death was due to infection by pathogenic bacteria. Interestingly, different coral colonies had different survival rates and, colony-specific microbiome signatures, indicating strong colony-specific variability in their response to warming waters. These results suggest that L. pertusa can only survive a long-term temperature increase of < 3 °C. Therefore, regional variations in deep-sea temperature increase should be considered in future estimates of the global distribution of cold-water corals.
Irradiance level and elevation shape the soil microbiome communities of Coffea arabica L
Tapaça IDPE, Obieze CC, Pereira GVM, Fangueiro D, Coutinho J, Fraga I, Partelli FL, Ramalho JC, Marques I and Ribeiro-Barros AI
The nexus plant-microbe-environment is essential to understand the ecosystem processes shaping plant health and fitness. Within this triangle, soils and associated microflora are among the key ecosystem's drivers, underpinning plant productivity and evolution. In this study, we conducted a comprehensive analysis (physicochemical properties, enzyme activities, and taxonomic diversity) of soils under the canopy projection of Coffea arabica trees along a gradient of elevation (600, 800, and 900 m) and shade (0, 50, 100%).
The composition of the arbuscular mycorrhizal fungal bacteriome is species dependent
Lahrach Z, Legeay J, Ahmed B and Hijri M
In addition to their role as endosymbionts for plant roots, arbuscular mycorrhizal fungi (AMF) engage in complex interactions with various soil microorganisms, the rhizosphere, and the root endosphere of host plants. They also host diverse prokaryotic groups within their mycelia, contributing to what is termed multipartite symbiosis. In this study, we examined the impact of three AMF species-Rhizophagus irregularis, R. clarus, and R. cerebriforme-combined with microbial bioaugmentation on the diversity and composition of bacterial communities in the mycelia and hyphosphere. Using a microcosm design to separate the influence of host plant roots from AMF mycelia and Illumina MiSeq amplicon sequencing to analyze the bacterial communities.
Unveiling the hidden world: How arbuscular mycorrhizal fungi and its regulated core fungi modify the composition and metabolism of soybean rhizosphere microbiome
Yang M, Song Y, Ma H, Li Z, Ding J, Yin T, Niu K, Sun S, Qi J, Lu G, Fazal A, Yang Y and Wen Z
The symbiosis between arbuscular mycorrhizal fungi (AMF) and plants often stimulates plant growth, increases agricultural yield, reduces costs, thereby providing significant economic benefits. AMF can also benefit plants through affecting the rhizosphere microbial community, but the underlying mechanisms remain unclear. Using Rhizophagus intraradices as a model AMF species, we assessed how AMF influences the bacterial composition and functional diversity through 16 S rRNA gene sequencing and non-targeted metabolomics analysis in the rhizosphere of aluminum-sensitive soybean that were inoculated with pathogenic fungus Nigrospora oryzae and phosphorus-solubilizing fungus Talaromyces verruculosus in an acidic soil.
The epidemic occurrence of decline disease in bayberry trees altered plant and soil related microbiome and metabolome
Ren H, Huang X, Wang Z, Abdallah Y, Ayoade SO, Qi X, Yu Z, Wang Q, Mohany M, Al-Rejaie SS, Li B and Li G
In China, decline disease with unknown etiology appeared as an epidemic among bayberry trees in the southern area of the Yangtze River. Furthermore, the use of beneficial microbes has been reported to be able to reduce the incidence of this disease, emphasizing the association of this disease with microorganisms. Therefore, it has become critical to uncover the microbiome's function and related metabolites in remodeling the immunity of bayberry trees under biotic or abiotic stresses.
Microbiome associated to an H-emitting zone in the São Francisco basin Brazil
Pinto OHB, Oliveira RDS, Ferreira BR, Peixoto J, Sartori MRS, Quirino BF, Brunet F and Kruger RH
Dihydrogen (H₂) natural gas is a clean and renewable energy source of significant interest in the transition to sustainable energy. Unlike conventional petroleum-based fuels, H₂ releases only water vapor upon combustion, making it a promising alternative for reducing carbon footprints in the future. However, the microbial impact on H₂ dynamics in H-emitting zones remains unclear, as does the origin of H - whether it is produced at greater depths or within shallow soil layers. In the São Francisco Basin, soil hydrogen concentrations of approximately 200 ppm were identified in barren ground depressions. In this study, we investigated the microbiome associated with this area using the 16S rRNA gene sequencing, with a focus on metabolic processes related to H₂ consumption and production. Soil samples were collected from two monitored (< 1 m) depths - 10 cm and 1 m - in the emission zone, which is predominantly covered with pasture vegetation, and from an adjacent area with medium and small trees.
Arctic's hidden hydrocarbon degradation microbes: investigating the effects of hydrocarbon contamination, biostimulation, and a surface washing agent on microbial communities and hydrocarbon biodegradation pathways in high-Arctic beaches
Chen YJ, Altshuler I, Freyria NJ, Lirette A, Góngora E, Greer CW and Whyte LG
Canadian Arctic summer sea ice has dramatically declined due to global warming, resulting in the rapid opening of the Northwest Passage (NWP), slated to be a major shipping route connecting the Atlantic and Pacific Oceans by 2040. This development elevates the risk of oil spills in Arctic regions, prompting growing concerns over the remediation and minimizing the impact on affected shorelines.