Variation In Community Structure Research Articles

Wolbachia and Asaia Distribution among Different Mosquito Vectors Is Affected by Tissue Localization and Host Species.

Microbial communities play an important role in the fitness of mosquito hosts. However, the factors shaping microbial communities in wild populations, with regard to interactions among microbial species, are still largely unknown. Previous research has demonstrated that two of the most studied mosquito symbionts, the bacteria Wolbachia and Asaia, seem to compete or not compete, depending on the genetic background of the reference mosquito host. The large diversity of Wolbachia-Asaia strain combinations that infect natural populations of mosquitoes may offer a relevant opportunity to select suitable phenotypes for the suppression of pathogen transmission and for the manipulation of host reproduction. We surveyed Wolbachia and Asaia in 44 mosquito populations belonging to 11 different species of the genera Anopheles, Aedes, and Culex using qualitative PCR. Through quantitative PCR, the amounts of both bacteria were assessed in different mosquito organs, and through metagenomics, we determined the microbiota compositions in some selected mosquito populations. We show that variation in microbial community structure is likely associated with the species/strain of mosquito, its geographical position, and tissue localization. Together, our results shed light on the interactions among different bacterial species in the microbial communities of mosquito vectors, and this can aid the development and/or improvement of methods for symbiotic control of insect vectors.

Effects of sweet pepper straw biochar on soil microbial communities and growth of continuously cropped cucumber

PurposeThis study evaluates biochar from crop residues as a solution to soil degradation in continuous monoculture within greenhouse agriculture, focusing on its impact on soil microbial communities and cucumber plant growth.MethodsWe analyzed biochar derived from tomato straw (TSB), sweet pepper straw (SPSB), and eggplant straw (ESB), assessing their nutrient content, cation exchange capacity, and adsorption rates. This study examined the effects of three concentrations (2.5%, 5%, and 7.5% w/w) of the more promising SPSB on soil properties and cucumber growth.ResultsSPSB showed significantly higher levels of nitrogen, phosphorus, and potassium, along with superior adsorption capacity compared to TSB and ESB. The 5% w/w SPSB concentration notably improved cucumber growth, increasing plant height by 13.01%, stem thickness by 20.79%, leaf area by 50.26%, and dry weight by 58.56% relative to the control. High-throughput sequencing revealed this concentration significantly altered soil microbial community structure, enhancing bacterial and fungal diversity. It increased beneficial bacterial groups (Firmicutes, Actinobacteria, Bacillus) and modified fungal communities, with a decrease in Ascomycota and Aspergillus and shifts in Penicillium abundance. Functional genomic analysis indicated enrichment in bacterial metabolic pathways and fungal replication and expression genes.ConclusionSPSB, especially at a 5% w/w concentration, emerges as an effective soil amendment in greenhouses affected by continuous monoculture. This approach represents a sustainable method to enhance soil health and crop productivity.

Effects of microtopography on soil microbial communities in alpine meadows on the Qinghai-Tibetan Plateau

Heterogeneous habitats generated by diverse microtopography are critical in shaping soil microbial communities and their ecological functions. In this study, a combination of high-throughput sequencing technology and functional prediction was used to assess the effects of three microtopographic types (the shady slope, ravine, and sunny slope) on community structure, diversity, functional guilds, and the co-occurrence networks of soil microbes in alpine meadows. The results showed that the microbial α-diversity varied significantly across the three microtopographies, and fungal community structure was more responsive to microtopography than that of bacteria. In contrast, the co-occurrence network pattern of bacteria was more sensitive to environmental changes induced by microtopography. Mantel tests revealed that bacterial community structure was mainly impacted by plant diversity, belowground biomass, soil total phosphorus content and soil pH, and variations in fungal community structure were correlated with plant diversity, soil pH, and soil NH4+–N content. Meanwhile, regression analyses indicated that nitrogen fixers, ectomycorrhizal fungi, and endophytes relative abundances were positively linked to plant diversity, and soil pH negatively affected nitrogen fixers, ectomycorrhizal fungi, and methane oxidizers. Furthermore, different functional guilds with similar functions (e.g., ectomycorrhizal fungi vs. arbuscular mycorrhizal fungi) responded inconsistently to the microtopography, suggesting ecological niche differentiation of microorganisms in microtopographies. These findings highlight the importance of microtopography for driving bacterial and fungal diversity, community structure, functional profiles and co-occurrence networks in alpine ecosystems.

The impacts of different seasons on macroinvertebrate community structure and functional diversity in the Jingui River, China

Species diversity and functional diversity indices reflect the variations of community structure and their responses to environmental stress. This study clarifies the biodiversity of macroinvertebrates in the Jingui River of Shenzhen and their response to the aquatic environment across different seasons. Utilizing ten functional traits, we conducted a seasonal survey at ten sampling points to examine changes in macroinvertebrate species and functional diversity, along with their relationships with environmental variables in the JGR. The results of the study demonstrated that the species and functional diversity of macroinvertebrates were significantly affected by season. Redundancy analysis indicated that water velocity, hydrogen ion concentration, turbidity, water depth, and total nitrogen were the most important factors for macroinvertebrate functional diversity. Moreover, structural equation modeling demonstrated that seasonal variations in total nitrogen, ammonia nitrogen, nitrate nitrogen, conductivity, water velocity, and hydrogen ion concentration directly or indirectly impacted the species diversity and functional diversity of macroinvertebrates. This study provides valuable information into the seasonal variation characteristics of macroinvertebrate communities, contributing to a more comprehensive understanding of biodiversity crucial for maintaining river ecosystem functioning and stability.

Environmental heterogeneity influences liana community differentiation across a Neotropical rainforest landscape.

We examined the variation in liana community composition and structure across geopedological land units to test the hypothesis that environmental heterogeneity is a driving force in liana community assembly. The study site was the Los Tuxtlas Tropical Biology Station, SE Mexico, a reserve that encompasses 640 ha of tropical rainforest. We sampled all lianas with basal diameter ≥1 cm in three 0.5-ha plots established in each of five land units (totaling 15 plots and 7.5 ha). We censused 6055 individuals and 110 species. Overall, the most speciose families were also the most abundant ones. Density and basal area of some dominant liana species differed among land units, and a permutational multivariate analysis of variance (PERMANOVA) and a non-metric multidimensional scaling ordination (NMDS) revealed differences in the presence, density, and basal area of liana species across the landscape. Liana composition and structure were highly heterogeneous among land units, suggesting that variations in soil water availability and relief are key drivers of liana community spatial differentiation. By showing that soil and topography play an important role at the landscape scale, we underscore the ecological relevance of environmental heterogeneity for liana community assembly. In the future, as our ability to assess the local environmental complexity increases, we will gain a better understanding of the liana community assembly process and their heterogeneous distribution in tropical forests.

Urbanization reduces Orthoptera diversity and changes community structure towards mobile species

Abstract Urban land use is regarded as one major driver for insect declines worldwide. We investigated how Orthoptera diversity and traits respond to the urban matrix and local vegetation parameters. Orthoptera were collected using a combined method of box‐quadrat sampling and pitfall trapping. We sampled 42 dry grasslands in Berlin, Germany, along gradients of urbanization (measured as proportion of sealed surface in the surrounding of the sites) and connectivity. We further included patch size and local vegetation parameters (plant richness, total vegetation cover, herb cover, neophyte cover) in our models. Urbanization was the main driver explaining Orthoptera species richness, Simpson diversity and functional diversity (functional dispersion), which all decreased with increasing proportion of sealed surface in the surrounding. Urbanization also influenced the Orthoptera species composition. Thereby, functional trait analyses revealed that the urban matrix acted as a habitat filter sorting towards mobile species. However, responses of the most common species showed that the effects of the urban matrix and vegetation parameters were species specific. Our results demonstrate predominantly negative effects of urbanization on Orthoptera diversity. Nevertheless, urban environments can provide important habitats, in particular for mobile species. Even small and isolated patches of dry grasslands can contribute to Orthoptera conservation in cities.

Different seasonal dynamics, ecological drivers, and assembly mechanisms of algae in southern and northern drinking water reservoirs

The role of environmental factors on the community structure of algae has been intensively studied, but there are few analyses on the assembly mechanism of the algal community structure. Here, changes in the community structure of algae in different seasons, the effects of environmental variables on the algal community structure, and the assembly mechanism of the algal community structure in northern and southern reservoirs were investigated in this study. The study revealed that Bacillariophyta, Cyanophyta, and Chlorophyta were the predominant algal species in the reservoirs, with Bacillariophyta and Cyanophyta exhibiting seasonal outbreaks. Compared to the northern reservoirs, the algal diversity in the southern reservoirs was greater. The diversity and algal community structure could be significantly impacted by variations in water temperature and nitrogen level. According to the ecological model, the interaction among algal communities in reservoirs was primarily cooperation. The key taxa in the northern reservoirs was Aphanizomenon sp., while the outbreak in the southern reservoirs was Coelosphaerium sp. The community formation pattern of reservoirs was stochastic, with a higher degree of explanation observed in the southern reservoirs compared to the northern reservoirs. This study preliminarily explored the assembly mechanism of the algal community, providing a theoretical basis for the control of eutrophication in drinking water reservoirs.

Vegetation Affects the Responses of Canopy Spider Communities to Elevation Gradients on Changbai Mountain, China.

Forest canopies, an essential part of forest ecosystems, are among the most highly threatened terrestrial habitats. Mountains provide ideal conditions for studying the variation in community structure with elevations. Spiders are one of the most abundant predators of arthropods in terrestrial ecosystems and can have extremely important collective effects on forest ecosystems. How the diversity and composition of canopy spider communities respond to elevation changes in temperate forests remains poorly understood. In this study, we collected canopy spiders from four elevation sites (800 m, 1100 m, 1400 m, and 1700 m) on Changbai Mountain using the fogging method in August 2016. With the methods of ANOVA analysis, transformation-based redundancy analysis, and random forest analysis, we explored the responses of canopy spider communities to elevation. In total, 8826 spiders comprising 81 species were identified and the most abundant families were Thomisidae, Clubionidae, Linyphiidae, and Theridiidae (77.29% of total individuals). Species richness decreased whereas evenness increased with increasing elevation, indicating that elevation has an important impact on community structure. The pattern of absolute abundance was hump shaped with increasing elevation. We found that the community compositions at the three taxonomic levels (species, family, and guild) along the elevation gradient were obviously altered and the variation in community composition was higher at low-elevation sites than at high-elevation sites. There were 19 common species (23.46%) among the four elevations. Regression and RDA results showed that vegetation variables contributed to the variation in the diversity and composition of canopy spiders. Furthermore, the influence of factors would be weakened with the taxonomic level increasing. Therefore, our findings greatly highlight the important role of vegetation in the diversity and composition of canopy spiders and the influence is closely related to the taxonomic level.

A Comparative Evaluation of eDNA Metabarcoding Primers in Fish Community Monitoring in the East Lake

East Lake in Wuhan, China, harbors a high number of freshwater fish species of great conservation value, concurrently serving as vital resources for local livelihoods. However, the ecosystem is threatened by an array of anthropogenic activities, thus requiring consistent monitoring of the local fish community to enable more efficacious conservation management. In place of conventional surveying methods, we undertook the first analysis of the fish distribution within East Lake via metabarcoding of environmental DNA (eDNA). The accuracy and efficacy of eDNA metabarcoding rely heavily upon selecting an appropriate primer set for PCR amplification. Given the varying environmental conditions and taxonomic diversity across distinct study systems, it remains a challenge to propose an optimal genetic marker for universal use. Thus, it becomes necessary to select PCR primers suitable for the composition of fish in the East Lake. Here, we evaluated the performance of two primer sets, Mifish-U and Metafish, designed to amplify 12S rRNA barcoding genes in fishes. Our results detected a total of 116 taxonomic units and 51 fish species, with beta diversity analysis indicating significant differences in community structure diversity between the six sampling locations encompassing East Lake. While it was difficult to accurately compare the species-level discriminatory power and amplification bias of the two primers, Mifish outperformed Metafish in terms of taxonomic specificity for fish taxa and reproducibility. These findings will assist with primer selection for eDNA-based fish monitoring and biodiversity conservation in the East Lake and other freshwater ecosystems.

A comparative analysis of soil physicochemical properties and microbial community structure among four shelterbelt species in the northeast China plain.

The focal point of this study lies in the implementation of a controlled experiment conducted under field conditions. In this experiment, we deliberately selected four shelterbelts within the same field, characterized by identical planting density, and planting year. This deliberate selection effectively mitigated the potential impact of extraneous factors on the three microbiomes, thereby enhancing the reliability and validity of our findings.

Critical factors driving spatiotemporal variability in the phytoplankton community structure of the coral habitat in Dongshan Bay, China.

This study investigated the spatiotemporal distribution of the phytoplankton in the coral habitat of Dongshan Bay (China), along with critical factors affecting the distribution, during June, August, and December 2022. Phytoplankton abundance in Dongshan Bay exhibited considerably temporal variation, peaking in June 2022, gradually decreasing thereafter, and reaching its lowest point in December 2022. The abundance of bottom-layer phytoplankton consistently exceeded that of the surface layer throughout all seasons. The average phytoplankton abundance in the coral habitat of Dongshan Bay was lower than that in non-coral habitat areas. Fluctuations in the Zhangjiang River and coastal upwelling influenced the diversity and community structure of the phytoplankton. Critical factors causing spatiotemporal variability in phytoplankton community structure included nutrient concentrations and seawater temperature. Nutrients played key roles in influencing various phytoplankton groups. Dominant diatom species, such as Thalassionema nitzschioides and Thalassiosira diporocyclus, were positively correlated with ammonia nitrogen, seawater salinity, coral cover, and the number of coral species present. In winter, Calanus sinicus exhibited a negative correlation with harmful algal bloom species. Additionally, it was found that both in the coral habitat and surrounding open sea, currents, nutrients, and zooplankton may play crucial roles in determining the spatiotemporal variability in the phytoplankton community structure.

The response pattern of the microbial community structure and metabolic profile of jiupei to Bacillus subtilis JP1 addition during baijiu fermentation.

Baijiu brewing is a complex and multifaceted multimicrobial co-fermentation process, in which various microorganisms interact to form an interdependent micro-ecosystem, subsequently influencing metabolic activities and compound production. Among these microorganisms, Bacillus, an important bacterial genus in the liquor brewing process, remains unclear in its role in shaping the brewing microbial community and its functional metabolism. A baijiu fermentation system was constructed using B. subtilis JP1 isolated from native jiupei (grain mixture) combined with daqu (a saccharifying agent) and huangshui (a fermentation byproduct). Based on high-throughput amplicon sequencing analysis, it was evident that B. subtilis JP1 significantly influences bacterial microbial diversity and fungal community structure in baijiu fermentation. Of these, Aspergillus and Monascus emerge as the most markedly altered microbial genera in the jiupei community. Based on co-occurrence networks and bidirectional orthogonal partial least squares discriminant analysis models, it was demonstrated that the addition of B. subtilis JP1 intensified microbial interactions in jiupei fermentation, consequently enhancing the production of volatile flavor compounds such as heptanoic acid, butyl hexanoate and 3-methylthiopropanol in jiupei. B. subtilis JP1 significantly alters the microbial community structure of jiupei, enhancing aroma formation during fermentation. These findings will contribute to a broader application in solid-state fermentation. © 2024 Society of Chemical Industry.

Primary productivity impacts community structure of euphausiids in the low-latitude Indian and Pacific Oceans

Euphausiids are a vital component of global marine micronekton. To reveal the primary environmental factors influencing euphausiid distribution patterns in the previously overlooked low-latitude ecosystems, we investigated a large-scale community structure of euphausiids covering the North Pacific subtropical gyre (NPSG) and low-latitude eastern Indian (EI), and South Pacific Oceans (SP). A total of 41 euphausiid species from six genera were identified. Integrated primary production (PP) correlated significantly with the euphausiid abundance and species diversity and displayed the most critical influence on the variations in euphausiid community structure in low latitudes. Dissolved oxygen (DO) was the second significant environmental driver. Due to the distinct distribution patterns of euphausiid species in response to different PP and DO levels, the low-latitude euphausiid assemblages were mainly distinguished into subtropical and tropical communities. The subtropical euphausiid community associated with lower PP and higher DO demonstrated significantly lower euphausiid abundance but higher diversity than the tropical community. Euphausia brevis, E. mutica, and Stylocheiron abbreviatum, which characterize the subtropical community, appear to depend less on the phytoplanktonic prey. Euphausia diomedeae and Hansarsia gracilis, typifying the tropical population, showed stronger hypoxia tolerance. Additionally, each community was further divided into three subgroups under the influence of surface PP (subtropical: marginal NPSG, central NPSG, and austral EI-SP subgroups; tropical: the Bay of Bengal, equatorial EI, and equatorial EI-SP subgroups). These results suggested that food resource is the most important in shaping euphausiids’ community structure in an oligotrophic ecosystem with subtle hydrography gradients.

Effects of protection and temperature variation on temporal stability in a marine reserve network.

Understanding the drivers of ecosystem stability has been a key focus of modern ecology as the impacts of the Anthropocene become more prevalent and extreme. Marine protected areas (MPAs) are tools used globally to promote biodiversity and mediate anthropogenic impacts. However, assessing the stability of natural ecosystems and responses to management actions is inherently challenging due to the complex dynamics of communities with many interdependent taxa. Using a 12-year time series of subtidal community structure in an MPA network in the Channel Islands (United States), we estimated species interaction strength (competition and predation), prey species synchrony, and temporal stability in trophic networks, as well as temporal variation in sea surface temperature to explore the causal drivers of temporal stability at community and metacommunity scales. At the community scale, only trophic networks in MPAs at Santa Rosa Island showed greater temporal stability than reference sites, likely driven by reduced prey synchrony. Across islands, competition was sometimes greater and predation always greater in MPAs compared with reference sites. Increases in interaction strength resulted in lower temporal stability of trophic networks. Although MPAs reduced prey synchrony at the metacommunity scale, reductions were insufficient to stabilize trophic networks. In contrast, temporal variation in sea surface temperature had strong positive direct effects on stability at the regional scale and indirect effects at the local scale through reductions in species interaction strength. Although MPAs can be effective management strategies for protecting certain species or locations, our findings for this MPA network suggest that temperature variation has a stronger influence on metacommunity temporal stability by mediating species interactions and promoting a mosaic of spatiotemporal variation in community structure of trophic networks. By capturing the full spectrum of environmental variation in network planning, MPAs will have the greatest capacity to promote ecosystem stability in response to climate change.

The effects of chemical fungicides and salicylic acid on the apple microbiome and fungal disease incidence under changing environmental conditions.

Epiphytic and endophytic micro-organisms associated with plants form complex communities on or in their host plant. These communities influence physiological traits, development, and host susceptibility to abiotic and biotic stresses, and these communities are theorized to have evolved alongside their hosts, forming a unit of selection known as the holobiont. The microbiome is highly variable and can be influenced by abiotic factors, including applied exogenous agents. In this study, we compared the impact of chemical fungicide and salicylic acid treatments on the fungal communities of "Honeycrisp" apples at harvest over two consecutive growing years. We demonstrated variations in fungal community structure and composition by tissue type, growing season, and treatment regimes and that fungicide treatments were associated with reduced network complexity. Finally, we show that the inclusion of salicylic acid with 50% less chemical fungicides in an integrated spray program allowed a reduction in fungicide use while maintaining effective control of disease at harvest and following storage.

Termites are key drivers of short‐term deadwood decay in Neotropical Cerrado across vegetation types

AbstractThe impact of deadwood in ecosystems is dependent on its longevity, as determined by decay rates controlled by decay agents. Despite the importance of macroclimate, significant variation of decay rates within a given macroclimatic envelope has been reported. Such variation may be driven by local‐scale microenvironmental conditions as regulated by the plant community structure as well as the presence of specific biotic and abiotic decay agents, decoupling the relation between macroclimate conditions and deadwood decay rates. In this study, we evaluated the relation between local‐scale variation in plant community structure with the decay rates of deadwood and the relative importance of biotic and abiotic decay agents in deadwood decay in Neotropical Cerrado. For this, we performed a wood mass loss experiment using Pinus taeda wood which was installed at three sites in three vegetation types differing in canopy cover—grasslands, savannas and woodlands; wood was divided into treatments according to deadwood exposure to decay agents—microorganism, termite and solar radiation. Across sites, we found termites and microbes decomposed wood twice as fast as microbes alone, while solar radiation was not a strong driver of deadwood decay in our sites. Additionally, local‐scale variation in plant community structure affected deadwood decay, as decay rates and frequency of wood blocks discovered by termites were lower in woodlands than in grasslands and savannas. Our study highlights the interactive effects of local‐scale variation in plant community structure and termites on deadwood turnover, mainly due to differences in termite foraging behaviour among vegetation types and highlights the key role of termites in deadwood decay throughout Neotropical savannas.

From wolves to humans: oral microbiome resistance to transfer across mammalian hosts.

The mammalian mouth is colonized by complex microbial communities, adapted to specific niches, and in homeostasis with the host. Individual microbes interact metabolically and rely primarily on nutrients provided by the host, with which they have potentially co-evolved along the mammalian lineages. The oral environment is similar across mammals, but the diversity, specificity, and evolution of community structure in related or interacting mammals are little understood. Here, we compared the oral microbiomes of dogs with those of wild wolves and humans. In dogs, we found an increased microbial diversity relative to wolves, possibly related to the transition to omnivorous nutrition following domestication. This includes a larger diversity of Patescibacteria than previously reported in any other oral microbiota. The oral microbes are most distinct at bacterial species or strain levels, with few if any shared between humans and canids, while the close evolutionary relationship between wolves and dogs is reflected by numerous shared taxa. More taxa are shared at higher taxonomic levels including with humans, supporting their more ancestral common mammalian colonization followed by diversification. Phylogenies of selected oral bacterial lineages do not support stable human-dog microbial transfers but suggest diversification along mammalian lineages (apes and canids). Therefore, despite millennia of cohabitation and close interaction, the host and its native community controls and limits the assimilation of new microbes, even if closely related. Higher resolution metagenomic and microbial physiological studies, covering a larger mammalian diversity, should help understand how oral communities assemble, adapt, and interact with their hosts.IMPORTANCENumerous types of microbes colonize the mouth after birth and play important roles in maintaining oral health. When the microbiota-host homeostasis is perturbed, proliferation of some bacteria leads to diseases such as caries and periodontitis. Unlike the gut microbiome, the diversity of oral microbes across the mammalian evolutionary space is not understood. Our study compared the oral microbiomes of wild wolves, dogs, and apes (humans, chimpanzees, and bonobos), with the aim of identifying if microbes have been potentially exchanged between humans and dogs as a result of domestication and cohabitation. We found little if any evidence for such exchanges. The significance of our research is in finding that the oral microbiota and/or the host limit the acquisition of exogenous microbes, which is important in the context of natural exclusion of potential novel pathogens. We provide a framework for expanded higher-resolution studies across domestic and wild animals to understand resistance/resilience.

The role of fish predators and their foraging traits in shaping zooplankton community structure.

Differentiation of foraging traits among predator populations may help explain observed variation in the structure of prey communities. However, few studies have investigated the phenotypic effects of predators on their prey in natural communities. Here, we use a comparative analysis of 78 Greenlandic lakes to examine how foraging trait variation among threespine stickleback populations can help explain variation in zooplankton community composition among lakes. We find that landscape-scale variation in zooplankton composition was jointly explained by lake properties, such as size and water chemistry, and the presence and absence of both stickleback and arctic char. Additional variation in zooplankton community structure can be explained by stickleback jaw protrusion, a trait with known utility for foraging on zooplankton, but only in lakes where stickleback co-occur with arctic char. Overall, our results illustrate how trait variation of predators, alongside other ecosystem properties, can influence the composition of prey communities in nature.

Impact of fecal sample preservation and handling techniques on the canine fecal microbiota profile.

Canine fecal microbiota profiling provides insight into host health and disease. Standardization of methods for fecal sample storage for microbiomics is currently inconclusive, however. This study investigated the effects of homogenization, the preservative RNAlater, room temperature exposure duration, and short-term storage in the fridge prior to freezing on the canine fecal microbiota profile. Within 15 minutes after voiding, samples were left non-homogenized or homogenized and aliquoted, then kept at room temperature (20-22°C) for 0.5, 4, 8, or 24 hours. Homogenized aliquots then had RNAlater added or not. Following room temperature exposure, all aliquots were stored in the fridge (4°C) for 24 hours prior to storing in the freezer (-20°C), or stored directly in the freezer. DNA extraction, PCR amplification, then sequencing were completed on all samples. Alpha diversity (diversity, evenness, and richness), and beta diversity (community membership and structure), and relative abundances of bacterial genera were compared between treatments. Homogenization and RNAlater minimized changes in the microbial communities over time, although minor changes in relative abundances occurred. Non-homogenized samples had more inter-sample variability and greater changes in beta diversity than homogenized samples. Storage of canine fecal samples in the fridge for 24 h prior to storage in the freezer had little effect on the fecal microbiota profile. Our findings suggest that if immediate analysis of fecal samples is not possible, samples should at least be homogenized to preserve the existing microbiota profile.

Structural and Functional Analysis of the Bacterial Community in the Soil of Continuously Cultivated Lonicera japonica Thunb. and Screening Antagonistic Bacteria for Plant Pathogens

Continuous cropping is the main form of cultivation in Chinese agriculture. The bacterial community plays an important role in maintaining the healthy growth of plants. However, there are few reports on the composition and dynamics of the bacterial community structure under continuous cropping of Lonicera japonica Thunb. High-throughput sequencing was used to monitor the variation in the soil bacterial community structure of different monocropping years of Lonicera japonica Thunb., as well as the correlation between soil characteristics and bacterial community. Meanwhile, antagonistic bacteria for Fusarium oxysporum pathogens were isolated and functionally verified by culture-dependent techniques and pot experiments. Bacterial community diversity and structure changed significantly with the increase in the years of Lonicera japonica Thunb. succession. However, some beneficial bacteria, such as Bacillus and Nitrosospira, were gradually depleted. The complexity of the bacteria co-occurrence networks decreased with increasing years of cropping. FAPROTAX-based functional prediction showed that the abundance of genes related to carbon, nitrogen, sulfur metabolism and chitinlysis were reduced with the extended crop succession. Furthermore, the three Bacillus strains that were strongly antagonistic toward Fusarium oxysporum and the pot experiment demonstrated they significantly promoted Lonicera japonica Thunb. growth. Our research provides theoretical support for the development of microbial fertilizers that are beneficial to plants.