Hasil untuk "Microbial ecology"

Meghan B. Parsley, Jesse L. Brunner, Erica J. Crespi et al.

ABSTRACT Environmental DNA (eDNA) is increasingly used to infer species abundance, but uncertainty remains about how well individual water samples reflect system‐wide eDNA concentrations. Currently, high levels of variation in estimated eDNA concentration among samples, even under similar conditions, limit the utility of eDNA estimates of abundance, especially in conservation and management scenarios. To investigate the sources and magnitude of variation in eDNA estimates, we analyzed eDNA from replicate water samples taken from mesocosms housing Lithobates sylvaticus tadpoles. We partitioned the variance of observed eDNA concentrations between biological replicates (distinct water samples) and technical replicates. We further tested whether stochastic variation in extraction efficiency (e.g., silica‐column DNA binding and elution) introduced variance using internal control DNA. We then trialed modifications of sampling methods that could be applied to improve precision, including increased water volume, spatially pooled subsamples, and modified filtration. The observed variance in eDNA concentrations was substantial, ~75% of which was attributable to variation among replicate samples from the same mesocosm and < 5% related to technical replicates; extraction‐related variance was negligible. Sampling modifications, like increasing sample volume and taking combined samples of multiple scoops, improved precision, while others highlighted potential trade‐offs between precision and accuracy. Our results suggest that sample‐to‐sample variation, even from seemingly homogeneous, controlled environments, can be substantial even under highly controlled conditions. This inherent variability imposes limits on the precision of abundance estimates derived from eDNA and underscores the importance of replication and protocol optimization in study design.

Zhanbiao Li, Wandi Luo, Huiting Xie et al.

Abstract Background Microbial assembly plays a critical role in ecosystem function and biodiversity. While numerous studies have explored the effect of abiotic factors on the belowground community assembly, much less is known about the role of biotic interactions, particularly viral infections, in shaping microbial communities. Southern rice black-streaked dwarf virus (SRBSDV), a member of the Fijivirus genus in the Reoviridae family, has caused severe yield losses in rice due to its rapid transmission. However, its specific effects on rhizosphere microbiota and the dynamics of microbial community changes have not been fully elucidated. Results By leveraging metabolomics with amplicon and metagenomics, this study provided a comprehensive understanding of the effect of SRBSDV infection on the rhizosphere microbial community and their functions. The results revealed that SRBSDV invasion led to significant changes in rhizosphere metabolites and microbial assembly processes. Specifically, the estimated overdispersion of cations sharply decreased following viral infection, while anion levels decreased markedly during early infection and then increased rapidly after 15 days. Key taxa, such as methanotrophs (e.g., Methylomicrobium), nitrifiers (e.g., Nitrospira), and iron-cycling bacteria (e.g., Sideroxydans), not only increased in abundance but also showed strong involvement in the microbial assembly processes. These key microbes were closely linked to specific metabolites and organized into two distinct network modules. Both modules predominantly recruited beneficial microbes, but one module also actively excluded potentially harmful taxa (e.g., Salmonella), which could disrupt community stability. Further experiments with exogenous metabolites confirmed the vital role of quercetin in attracting beneficial microbes while repelling harmful ones. Conclusion The findings indicate that arboviruses can strongly influence the belowground rhizosphere microbial assembly processes by modulating metabolite profiles to selectively recruit or exclude key microbial species. These taxa, in turn, play fundamental roles in rhizosphere functions. These insights lay the groundwork for strategies to enhance rice immunity against viral infections by managing the rhizosphere microbial community. Video Abstract

Barbara Salerno, Matteo Cornaggia, Raffaella Sabatino et al.

IntroductionFarms are significant hotspots for the dissemination of antibiotic-resistant bacteria and genes (ARGs) into the environment and directly to humans. The prevalence of ARGs on farms underscores the need for effective strategies to reduce their spread. This study aimed to evaluate the impact of a guideline on “best practices for farming” aimed at reducing the dissemination of antibiotic resistance.MethodsA guideline focused on prudent antibiotic use, selective therapy, and hygienic and immune-prophylactic practices was developed and provided to the owners of 10 selected dairy farms and their veterinarians. Fecal samples were collected from lactating cows, dry cows, and calves both before and after the implementation of the guideline. ARGs (blaTEM, ermB, sul2, and tetA) were initially screened by end-point PCR, followed by quantification using digital droplet PCR. ARG abundance was expressed in relative terms by dividing the copy number of ARGs by the copy number of the 16S rRNA gene.ResultsThe ARG abundances were higher in lactating cows compared to other categories. Despite similar levels of antibiotic administration (based on veterinary prescription data from the sampled farms) in both sampling campaigns, the total abundance of selected ARGs, particularly blaTEM and tetA, significantly decreased after the adoption of the farming guidelines.DiscussionThis study highlights the positive impact of prudent antibiotic use and the implementation of farming best practices in reducing the abundance of ARGs. The lactating cow category emerged as a crucial point of intervention for reducing the spread of antibiotic resistance. These findings contribute to ongoing efforts to address antibiotic resistance in farm environments and strengthen the evidence supporting the adoption of good farming practices.

Chang-Eon Park, Hee-Cheon Park

The water deer, although an internationally endangered species, is designated as a nuisance wild animal in South Korea and occupies a unique ecological niche. Studying the gut microbiome of this species is crucial for understanding its ecology. We amplified 16S rRNA DNA and compared the gut microbiomes of wild water deer from three regions with those of captive water deer from one region. Our results showed that the gut microbiome diversity of water deer did not differ significantly across regions in the wild but decreased significantly when raised in captivity. The similar microbiomes of water deer living in different regions are believed to be due to dietary diversity rather than dietary homogeneity. Furthermore, the monotony of the food supply appears to lead to significant variation in captive environments. From a conservation biology and biorestoration perspective, we suggest the importance of conserving the gut environments of animals conserved and restored outside their native habitats.

Chen Meng, Siyuan Feng, Zikai Hao et al.

Abstract Strains of Roseburia inulinivorans, Bacteroides uniformis, and Eubacterium rectale have exhibited multi-pathway therapeutic efficacy against anxiety and depression-like behaviors in chronic unpredictable mild stress (CUMS) rats. However, the combined therapeutic effects of these strains remain to be elucidated. Behavioral tests showed that a mixture of these strains reduced anxiety and depression-like behaviors. 16S rRNA sequencing revealed that the mixtures decrease the relative abundance of potentially pathogenic bacteria within the gut microbiota. Furthermore, the mixture increased the levels of butyric, isobutyric, and isovaleric acids in the gut and decreased pro-inflammatory factors in serum. It also lowered diamine oxidase, histamine in brain tissue, increased DL-kynurenine, and reduced cortisol secretion by the hypothalamic pituitary adrenal axis. In summary, the mixture significantly alleviated anxiety and depression-like behaviors.

Daniel I. Peters, Iris J. Shin, Alyssa N. Deever et al.

ABSTRACT Bacterial strains that are genetically engineered to constitutively produce fluorescent proteins have aided our study of bacterial physiology, biofilm formation, and interspecies interactions. Here, we report on the construction and utilization of new strains that produce the blue fluorescent protein mTagBFP2, the green fluorescent protein sfGFP, and the red fluorescent protein mScarlet-I3 in species Streptococcus gordonii, Streptococcus mutans, and Streptococcus sanguinis. Gene fragments, developed to contain the constitutive promoter Pveg, the fluorescent gene of interest, as well as aad9, providing resistance to the antibiotic spectinomycin, were inserted into selected open reading frames on the chromosome that were both transcriptionally silent and whose loss caused no measurable changes in fitness. All strains, except for sfGFP in S. sanguinis, were validated to produce a detectable and specific fluorescent signal. Individual stains, along with extracellular polymeric substances (EPS) within biofilms, were visualized and quantified through either widefield or super-resolution confocal microscopy approaches. Finally, to validate the ability to perform single-cell-level analysis using the strains, we imaged and analyzed a triculture mixed-species biofilm of S. gordonii, S. mutans, and S. sanguinis grown with and without the addition of human saliva. Quantification of the loss in membrane integrity using a SYTOX dye revealed that all strains had increased loss of membrane integrity with water or human saliva added to the growth media, but the proportion of the population stained by the SYTOX dye varied by species. In all, these fluorescent strains will be a valuable resource for the continued study of oral microbial ecology.IMPORTANCEStreptococci are among the earliest colonizers of the soft and hard tissues of the oral cavity and are contributors to the oral health status of the host, with involvement in dental caries, endodontic infections, periodontal disease, and the development of oral cancer. Strains genetically modified to produce fluorescent proteins that can be either visualized through microscopy imaging or quantified by their specific fluorescent intensity signal are critical tools toward the study of individual or mixed-species cultures. Our report here details the development and testing of several new strains of fluorescent oral streptococci that can be utilized in the study of microbial ecology, increasing both the availability of tools and documenting experimental approaches toward in vitro assay applications such as the study of intermicrobial interactions.

Gorkhmaz Abbaszade, Kathrin Stückrath, Susann Müller

Abstract Colonies of pure bacterial strains are highly dense cellular structures organised in distinct and typical arrangements. The size, shape and variability of bacterial colonies are strongly species‐dependent and also influenced by environmental conditions. However, the spatial organization of individual cells is unknown for most strains. By introducing a local biopsy technique, this study aimed to provide a means to study the local diversification of the structure of bacterial colonies. Cells were biopsied at different sites of a colony and analysed by microbial flow cytometry using cytometric fingerprints for both fixed and viable cells, which divided the biopsied samples into many heterogeneous cell states. This two‐step resolution was performed on five bacterial strains: Bacillus subtilis, Paenibacillus polymyxa, Kocuria rhizophila, Stenotrophomonas rhizophila and Pseudomonas citronellolis. The effects of biopsy tool size (27G needle and 10, 200, and 1000 μL pipette tips) and sampling site on the precision of the technique were tested by using both gate settings along Gaussian distributions of subpopulations and a grid gating tool, as well as the t‐distributed stochastic neighbour embedding (t‐SNE) method. The biopsy technique uncovered significant heterogeneity among the cells within bacterial colonies, identifying differences in cell cycle stages, the proportion of live and dead cells, and the abundance of spore types. Cells from different biopsy sites displayed distinct physiological states, revealing that colony structure is far more complex than previously understood. The technique's precision depends on the biopsy tool size, dye equilibration, and cell handling, underscoring the importance of method calibration. The biopsy method, combined with cytometric fingerprinting, provided insights within only 15–45 min and is universally applicable. The study provides a high‐resolution biopsy technique that explores the spatial distribution of cell types and their heterogeneous physiological cell states, allowing conclusions to be drawn from biopsy composition at different sites to overarching functions of the entire bacterial colony. This method also facilitates downstream analysis through further cell sorting, offering a powerful approach for future functional investigations.

Iván Sánchez-Castro, Tomeu Viver, Pablo Martínez-Rodríguez et al.

A Gram-stain-negative bacterial strain designated Be4T, belonging to the genus Acidovorax, was isolated from mining porewaters sampled in uranium mill tailings repository sites, located in Bellezane, near Bessines-sur-Gartempe (Limousin, France). Cells were facultative anaerobic, rod-shaped, non-endospore-forming and motile with flagella. The mean cell size was 1.25–1.31 μm long and 0.70–0.73 μm wide. Colonies were light yellow, opaque, circular, convex with smooth margins, and 1–2 mm in diameter. Growth occurs at 4–37 °C and between pH 5.5–9.0. It differed from its phylogenetically related strains by phenotypic and physiological characteristics such as growth at 4 °C, presence of acid phosphatase, naphthol-AS-BI-phosphohydrolase and β-glucosidase enzymatic activities, and fermentation of l-xylose and esculin. The major fatty acids were C16:0, C16:1 ω7c/C16:1 ω6c, C17:0 cyclo and C18:1 ω7c. Phylogenetic analysis based on 16S rRNA and 938 core genes, confirmed its placement within the genus Acidovorax as a novel species. Strain Be4T showed highest 16S rRNA sequence similarity to Acidovorax antarcticus (98.2 %), Acidovorax radicis (97.9 %), Acidovorax temperans (97.8 %) and Acidovorax facilis (97.7 %). The genome of strain Be4T is 5,041,667 bp size with a DNA G + C content of 65.15 %. By automatic annotation numerous sequences involved in the interaction with metals/metalloids including some genes related to Se uptake and selenite resistance were detected in its genome. The average nucleotide identity (ANI) values calculated from whole genome sequences between strain Be4T and the most closely related strains A. radicis and A. facilis were below the threshold value of 95 %. Thus, the data from the phylogenetic, physiological, biochemical, and genomic analyses clearly indicates that strain Be4T represents a novel species with the suggested name Acidovorax bellezanensis sp. nov. The type strain is Acidovorax bellezanensis Be4T (=DSM116209T = CECT30865T). This novel species, due to its unique isolation source, genomic analysis, and preliminary laboratory tests where it was able to reduce toxic Se(IV) to less harmful Se(0) in the form of nanoparticles, holds great potential for further investigation in bioremediation, particularly concerning Se.

Nathan I. Johns, Tomasz Blazejewski, Antonio L. C. Gomes et al.

Pauline Vannier, Gregory K. Farrant, Alexandra Klonowski et al.

Skaftárkatlar are two subglacial lakes located beneath the Vatnajökull ice cap in Iceland associated with geothermal and volcanic activity. Previous studies of these lakes with ribosomal gene (16S rDNA) tag sequencing revealed a limited diversity of bacteria adapted to cold, dark, and nutrient-poor waters. In this study, we present analyses of metagenomes from the lake which give new insights into its microbial ecology. Analyses of the 16S rDNA genes in the metagenomes confirmed the existence of a low-diversity core microbial assemblage in the lake and insights into the potential metabolisms of the dominant members. Seven taxonomic genera, Sulfuricurvum, Sulfurospirillum, Acetobacterium, Pelobacter/Geobacter, Saccharibacteria, Caldisericum, and an unclassified member of Prolixibacteraceae, comprised more than 98% of the rDNA reads in the library. Functional characterisation of the lake metagenomes revealed complete metabolic pathways for sulphur cycling, nitrogen metabolism, carbon fixation via the reverse Krebs cycle, and acetogenesis. These results show that chemolithoautotrophy constitutes the main metabolism in this subglacial ecosystem. This assemblage and its metabolisms are not reflected in enrichment cultures, demonstrating the importance of in situ investigations of this environment.

Dongdong Wei, Yuan Cheng, Wenyu Liao et al.

Skin microbiota play an important role in skin barrier function and are associated with host health. The study of the skin microbiota is beneficial for managing disease with skin microbiota. Bullfrog (Rana catesbeiana) is an important cultured animal. Bacterial diseases like red leg syndrome (RLS) often occur in bullfrog cultured and cause huge economic losses around the world. However, the appearance of RLS is unknown. Here we compare the skin microbiota of RLS bullfrog and healthy bullfrog by 16 S rRNA microbiome profiles. The bacterial community diversity of bullfrog skin was significantly different between RLS and healthy group. Proteobacteria, Bacteroidota, Firmicutes were the most abundant phyla in bullfrog skin. Compared with healthy bullfrogs, RLS bullfrogs had high abundance of Acinetobacter, Chryseobacterium, Elizabethkingia, Flavobacterium and Streptococcus in skin microbiota, but the relative abundance of Cetobacterium, Bacteroides and Shewanella was overrepresented in the RLS bullfrog. The Tax4Fun function prediction showed that the relative abundance of genes associated with Nucleotide metabolism, Translation, Nucleotide metabolism, Translation, Glycan biosynthesis and metabolism exhibited was significantly higher in RLS bullfrogs. The results suggested that the RLS significantly changed the composition and predictive function of the skin bacterial community in cultured bullfrogs. This study is the first to report on the relationship between skin microbiota and red leg syndrome of bullfrog, which can expand our understanding of bacterial communities in bullfrog farming from the perspective of microbial ecology and help prevent and manage RLS in bullfrog farming.

Keke Cheng, Xinyang Li, Mengmeng Tong et al.

ABSTRACT Coral bleaching has been rapidly increasing in recent years due to abnormally elevated temperature, leading to massive damage to coral reefs worldwide. Understanding the processes and micro-ecological mechanisms of coral symbionts in response to bleaching is crucial as evidence accumulates that micro-organisms (particularly the bacteria) contribute to the health and recovery of coral, especially during heat stress. However, the exact functional mechanism of bacteria has not yet been fully elucidated. In this study, we performed metagenomic and metaproteomic analyses of healthy and bleached Acropora muricata corals to identify taxonomic and functional shifts in coral symbionts during a natural thermal bleaching event on Hainan Island. The results showed that symbiont species tended to be more abundant in bleached corals than healthy corals, and the bacterial community appeared to be crucial to coral bleaching. The relative abundance of opportunistic pathogens dramatically increased in bleached corals, accompanied by the reduction of beneficial bacteria. In addition, a direct comparison of metagenomic data sets indicated major changes in functional genes, with bleached corals exhibiting significant metabolic enrichment, while healthy corals maintained lower metabolism and energy consumption. Carbohydrate-active enzyme genes were remarkably activated, and virulence factors were highly represented in bleached corals, which was directly related to the increased abundance of pathogenic bacteria. Metaproteomic analysis also demonstrated that bleaching greatly affected photosynthesis and energy metabolism of coral symbionts. Among them, the biological processes of photosynthesis and chlorophyll biosynthesis were common in healthy corals, while pathways involved in gluconeogenesis and apoptosis were significantly enriched in bleached corals. Bacteria-mediated processes in healthy corals contribute to maintaining the basic functions of symbionts and resisting stress, whereas the proliferation of pathogenic bacteria in bleached corals leads to metabolic abnormalities of symbionts, showing enhanced energy metabolism and catalytic activity. In summary, the two omics analyzes revealed that bleaching caused enormous physiological damage to corals, and bacterial imbalance and dysfunction were the potential micro-ecological mechanisms underlying this event.IMPORTANCECoral reefs worldwide are facing rapid decline due to coral bleaching. However, knowledge of the physiological characteristics and molecular mechanisms of coral symbionts respond to stress is scarce. Here, metagenomic and metaproteomic approaches were utilized to shed light on the changes in the composition and functions of coral symbiotic bacteria during coral bleaching. The results demonstrated that coral bleaching significantly affected the composition of symbionts, with bacterial communities dominating in bleached corals. Through differential analyses of gene and protein expression, it becomes evident that symbionts experience functional disturbances in response to heat stress. These disturbances result in abnormal energy metabolism, which could potentially compromise the health and resilience of the symbionts. Furthermore, our findings highlighted the highly diverse microbial communities of coral symbionts, with beneficial bacteria providing critical services to corals in stress responses and pathogenic bacteria driving coral bleaching. This study provides comprehensive insights into the complex response mechanisms of coral symbionts under heat stress from the micro-ecological perspective and offers fundamental data for future monitoring of coral health.

Yue Clare Lou, Jordan Hoff, Matthew R. Olm et al.

Abstract Background Metagenomics analyses can be negatively impacted by DNA contamination. While external sources of contamination such as DNA extraction kits have been widely reported and investigated, contamination originating within the study itself remains underreported. Results Here, we applied high-resolution strain-resolved analyses to identify contamination in two large-scale clinical metagenomics datasets. By mapping strain sharing to DNA extraction plates, we identified well-to-well contamination in both negative controls and biological samples in one dataset. Such contamination is more likely to occur among samples that are on the same or adjacent columns or rows of the extraction plate than samples that are far apart. Our strain-resolved workflow also reveals the presence of externally derived contamination, primarily in the other dataset. Overall, in both datasets, contamination is more significant in samples with lower biomass. Conclusion Our work demonstrates that genome-resolved strain tracking, with its essentially genome-wide nucleotide-level resolution, can be used to detect contamination in sequencing-based microbiome studies. Our results underscore the value of strain-specific methods to detect contamination and the critical importance of looking for contamination beyond negative and positive controls. Video Abstract

Ana Shein Lee Díaz, Muhammad Syamsu Rizaludin, Hans Zweers et al.

Plants produce volatile organic compounds that are important in communication and defense. While studies have largely focused on volatiles emitted from aboveground plant parts upon exposure to biotic or abiotic stresses, volatile emissions from roots upon aboveground stress are less studied. Here, we investigated if tomato plants under insect herbivore attack exhibited a different root volatilome than non-stressed plants, and whether this was influenced by the plant’s genetic background. To this end, we analyzed one domesticated and one wild tomato species, i.e., <i>Solanum lycopersicum cv</i> Moneymaker and <i>Solanum pimpinellifolium,</i> respectively, exposed to leaf herbivory by the insect <i>Spodoptera exigua.</i> Root volatiles were trapped with two sorbent materials, HiSorb and PDMS, at 24 h after exposure to insect stress. Our results revealed that differences in root volatilome were species-, stress-, and material-dependent. Upon leaf herbivory, the domesticated and wild tomato species showed different root volatile profiles. The wild species presented the largest change in root volatile compounds with an overall reduction in monoterpene emission under stress. Similarly, the domesticated species presented a slight reduction in monoterpene emission and an increased production of fatty-acid-derived volatiles under stress. Volatile profiles differed between the two sorbent materials, and both were required to obtain a more comprehensive characterization of the root volatilome. Collectively, these results provide a strong basis to further unravel the impact of herbivory stress on systemic volatile emissions.

Alvaro Duque, Miguel A. Peña, Francisco Cuesta et al.

Ramiro Logares, Ina M. Deutschmann, Pedro C. Junger et al.

Abstract Background The ocean microbiota modulates global biogeochemical cycles and changes in its configuration may have large-scale consequences. Yet, the underlying ecological mechanisms structuring it are unclear. Here, we investigate how fundamental ecological mechanisms (selection, dispersal and ecological drift) shape the smallest members of the tropical and subtropical surface-ocean microbiota: prokaryotes and minute eukaryotes (picoeukaryotes). Furthermore, we investigate the agents exerting abiotic selection on this assemblage as well as the spatial patterns emerging from the action of ecological mechanisms. To explore this, we analysed the composition of surface-ocean prokaryotic and picoeukaryotic communities using DNA-sequence data (16S- and 18S-rRNA genes) collected during the circumglobal expeditions Malaspina-2010 and TARA-Oceans. Results We found that the two main components of the tropical and subtropical surface-ocean microbiota, prokaryotes and picoeukaryotes, appear to be structured by different ecological mechanisms. Picoeukaryotic communities were predominantly structured by dispersal-limitation, while prokaryotic counterparts appeared to be shaped by the combined action of dispersal-limitation, selection and drift. Temperature-driven selection appeared as a major factor, out of a few selected factors, influencing species co-occurrence networks in prokaryotes but not in picoeukaryotes, indicating that association patterns may contribute to understand ocean microbiota structure and response to selection. Other measured abiotic variables seemed to have limited selective effects on community structure in the tropical and subtropical ocean. Picoeukaryotes displayed a higher spatial differentiation between communities and a higher distance decay when compared to prokaryotes, consistent with a scenario of higher dispersal limitation in the former after considering environmental heterogeneity. Lastly, random dynamics or drift seemed to have a more important role in structuring prokaryotic communities than picoeukaryotic counterparts. Conclusions The differential action of ecological mechanisms seems to cause contrasting biogeography, in the tropical and subtropical ocean, among the smallest surface plankton, prokaryotes and picoeukaryotes. This suggests that the idiosyncrasy of the main constituents of the ocean microbiota should be considered in order to understand its current and future configuration, which is especially relevant in a context of global change, where the reaction of surface ocean plankton to temperature increase is still unclear. Video Abstract

Robin-Tobias Jauss, Susanne Walden, Anna Maria Fiore-Donno et al.

Tree canopies provide habitats for diverse and until now, still poorly characterized communities of microbial eukaryotes. One of the most general patterns in community ecology is the increase in species richness with increasing habitat diversity. Thus, environmental heterogeneity of tree canopies should be an important factor governing community structure and diversity in this subsystem of forest ecosystems. Nevertheless, it is unknown if similar patterns are reflected at the microbial scale within unicellular eukaryotes (protists). In this study, high-throughput sequencing of two prominent protistan taxa, Cercozoa (Rhizaria) and Oomycota (Stramenopiles), was performed. Group specific primers were used to comprehensively analyze their diversity in various microhabitats of a floodplain forest from the forest floor to the canopy region. Beta diversity indicated highly dissimilar protistan communities in the investigated microhabitats. However, the majority of operational taxonomic units (OTUs) was present in all samples, and therefore differences in beta diversity were mainly related to species performance (i.e., relative abundance). Accordingly, habitat diversity strongly favored distinct protistan taxa in terms of abundance, but due to their almost ubiquitous distribution the effect of species richness on community composition was negligible.

Cui-Jing Zhang, Jie Pan, Chang-Hai Duan et al.

ABSTRACT Mangroves, as a blue carbon reservoir, provide an environment for a variety of microorganisms. Mangroves lie in special locations connecting coastal and estuarine areas and experience fluctuating conditions, which are expected to intensify with climate change, creating a need to better understand the relative roles of stochastic and deterministic processes in shaping microbial community assembly. Here, a study of microbial communities inhabiting mangrove sediments across southeastern China, spanning mangroves in six nature reserves, was conducted. We performed high-throughput DNA sequencing of these samples and compared them with data of 1,370 sediment samples collected from the Earth Microbiome Project (EMP) to compare the microbial diversity of mangroves with that of other biomes. Our results showed that prokaryotic alpha diversity in mangroves was significantly higher than that in other biomes and that microbial beta diversity generally clustered according to biome types. The core operational taxonomic units (OTUs) in mangroves were mostly assigned to Gammaproteobacteria, Deltaproteobacteria, Chloroflexi, and Euryarchaeota. The majority of beta nearest-taxon index values were higher than 2, indicating that community assembly in mangroves was better explained through a deterministic process than through a stochastic process. Mean annual precipitation (MAP) and total organic carbon (TOC) were main deterministic factors explaining variation in the microbial community. This study fills a gap in addressing the unique microbial diversity of mangrove ecosystems and their microbial community assembly mechanisms. IMPORTANCE Understanding the underlying mechanisms of microbial community assembly patterns is a vital issue in microbial ecology. Mangroves, as an important and special ecosystem, provide a unique environment for examining the relative importance of stochastic and deterministic processes. We made the first global-scale comparison and found that microbial diversity was significantly different in mangrove sediments compared to that of other biomes. Furthermore, our results suggest that a deterministic process is more important in shaping microbial community assembly in mangroves.

K. Warren-Rhodes, K. Warren-Rhodes, K. Rhodes et al.

E. Monte