Community Structure Of Microorganisms Research Articles

Combined Effects of Tetracycline and Copper Ion on Microorganisms During the Biological Phosphorus Removal.

Tetracycline and copper ion are common pollutants in wastewater, and the effects of mixed pollutants on microorganisms in wastewater biological treatment have been less studied. In order to reveal the effects of mixed pollutants of tetracycline and copper ion on the microorganisms during the biological phosphorus removal, three ratios of tetracycline and copper ions were designed by the direct equipartition ray method. The relative abundance and diversity of microbial community were investigated, and the microbial interactions were revealed through microbiological methods. The results demonstrated that, for three different ratios, the inhibitory effect of specific phosphorus uptake rate became more significant with the increase of the tetracycline-copper ions concentration and the reaction time. The microbial community decreased with the increase of the proportion of tetracycline in different ratios. The relative abundance of Acinetobacter decreased with the increase of the proportion of tetracycline, while the relative abundance of Ca.Competibacter was higher under the conditions of low mixtures concentrations. Positive interactions and symbiotic relationships among microorganisms were predominant for three different ratios. However, as the proportion of tetracycline increased, the community structure of microorganisms shifted from phosphate-accumulating organisms to glycogen accumulating organisms and denitrifying bacteria. This study can provide a reference for the effect of mixed pollutants on microorganisms and the mechanism of wastewater treatment.

Effects of Short-Term Tillage on Rhizosphere Soil Nitrogen Mineralization and Microbial Community Composition in the Double-Cropping Rice Field.

Soil extracellular enzyme plays a vital role in changing soil nitrogen (N) mineralization of rice field. However, the effects of soil extracellular enzyme activities (EEA) and microbial community composition response to N mineralization of rice field under short-term tillage treatment needed to be further explored. In this study, we investigated the impact of short-term (8-year) tillage practices on rhizosphere soil N transformation rate, soil enzyme activities, soil microorganism community structure and their N mineralization function genes in double-cropping rice field in southern China. The experiment consisted of four tillage treatments: rotary tillage with crop straw input (RT), conventional tillage with crop straw input (CT), no-tillage with crop straw retention (NT), and rotary tillage with all crop straws removed as a control (RTO). The results indicated that rhizosphere soil N transformation rate in paddy field in NT and RTO treatments were significantly lower than that in RT and CT treatments. Compared with NT and RTO treatments, soil protease, urease, β-glucosaminidase and arginase activities with CT treatment were significantly improved, as were abundances of soil sub, npr and chiA with CT and RT treatments. Moreover, diversity of overall soil bacterial communities in NT and RTO treatments were significantly lower than that in RT and CT treatments. Soil chitinolytic and bacterial ureolytic communities were also obviously changed combined with tillage and crop straw input practices.

Polyvinyl chloride microplastics in the aquatic environment enrich potential pathogenic bacteria and spread antibiotic resistance genes in the fish gut

Microplastics and antibiotics coexist in aquatic environments, especially in freshwater aquaculture areas. However, as the second largest production of polyvinyl chloride (PVC) in the world, the effects of co-exposure to microplastics particles and antibiotics on changes in antibiotic resistance gene (ARG) profiles and the microbial community structure of aquatic organism gut microorganisms are poorly understood. Therefore, in this study, carp (Cyprinus carpio) were exposed to single or combined PVC microplastic contamination and oxytetracycline (OTC) or sulfamethazine (SMZ) for 8 weeks. PVC microplastics can enrich potential pathogenic bacteria, such as Enterobacter and Acinetobacter, among intestinal microorganisms. The presence of PVC microplastics enhanced the selective enrichment and dissemination risk of ARGs. PVC microplastics combined with OTC (OPVC) treatment significantly increased the abundance of tetracycline resistance genes (1.40-fold) compared with that in the OTC exposure treatment, revealing an obvious co-selection effect. However, compared with those in the control group, the total abundance of ARGs and MGEs in the OPVC treatment groups were significantly lower, which was correlated with the reduced abundances of the potential host Enterobacter. Overall, our results emphasized the diffusion and spread of ARGs are more influenced by PVC microplastics than by antibiotics, which may lead to antibiotic resistance in aquaculture.

Effects of nitrogen application on ammonium assimilation and microenvironment in the rhizosphere of drip-irrigated sunflower under plastic mulch.

This study investigated the effect of nitrogen application on the rhizosphere soil microenvironment of sunflower and clarified the relationship between ammonium assimilation and the microenvironment. In a field experiment high (HN, 190 kg/hm2), medium (MN, 120 kg/hm2) and low nitrogen (CK, 50 kg/hm2) treatments were made to replicate plots of sunflowers using drip irrigation. Metagenomic sequencing was used to analyze the community structure and functional genes involved in the ammonium assimilation pathway in rhizosphere soil. The findings indicated that glnA and gltB played a crucial role in the ammonium assimilation pathway in sunflower rhizosphere soil, with Actinobacteria and Proteobacteria being the primary contributors. Compared with CK treatment, the relative abundance of Actinobacteria increased by 15.57% under MN treatment, while the relative abundance decreased at flowering and maturation stages. Conversely, the relative abundance of Proteobacteria was 28.57 and 61.26% higher in the MN treatment during anthesis and maturation period, respectively, compared with the CK. Furthermore, during the bud stage and anthesis, the abundance of Actinobacteria, Proteobacteria, and their dominant species were influenced mainly by rhizosphere soil EC, ammonium nitrogen (-N), and nitrate nitrogen (-N), whereas, at maturity, soil pH and -N played a more significant role in shaping the community of ammonium-assimilating microorganisms. The MN treatment increased the root length density, surface area density, and root volume density of sunflower at the bud, flowering, and maturity stages compared to the CK. Moreover, root exudates such as oxalate and malate were positively correlated with the dominant species of Actinobacteria and Proteobacteria during anthesis and the maturation period. Under drip irrigation, applying 120 kg/hm2 of nitrogen to sunflowers effectively promoted the community structure of ammonium-assimilating microorganisms in rhizosphere soil and had a positive influence on the rhizosphere soil microenvironment and sunflower root growth.

Tea and Pleurotus ostreatus intercropping modulates structure of soil and root microbial communities.

Intercropping with Pleurotus ostreatus has been demonstrated to increase the tea yield and alleviate soil acidification in tea gardens. However, the underlying mechanisms remain elusive. Here, high-throughput sequencing and Biolog Eco analysis were performed to identify changes in the community structure and abundance of soil microorganisms in the P. ostreatus intercropped tea garden at different seasons (April and September). The results showed that the soil microbial diversity of rhizosphere decreased in April, while rhizosphere and non-rhizosphere soil microbial diversity increased in September in the P. ostreatus intercropped tea garden. The diversity of tea tree root microorganisms increased in both periods. In addition, the number of fungi associated with organic matter decomposition and nutrient cycling, such as Penicillium, Trichoderma, and Trechispora, was significantly higher in the intercropped group than in the control group. Intercropping with P. ostreatus increased the levels of total nitrogen (TN), total phosphorus (TP), and available phosphorus (AP) in the soil. It also improved the content of secondary metabolites, such as tea catechins, and polysaccharides in tea buds. Microbial network analysis showed that Unclassified_o__Helotiales, and Devosia were positively correlated with soil TN and pH, while Lactobacillus, Acidothermus, and Monascus were positively correlated with flavone, AE, and catechins in tea trees. In conclusion, intercropping with P. ostreatus can improve the physical and chemical properties of soil and the composition and structure of microbial communities in tea gardens, which has significant potential for application in monoculture tea gardens with acidic soils.

Epiphytic and endophytic bacteria on Camellia oleifera phyllosphere: exploring region and cultivar effect

The epiphytic and endophytic bacteria play an important role in the healthy growth of plants. Both plant species and growth environmental influence the bacterial population diversity, yet it is inconclusive whether it is the former or the latter that has a greater impact. To explore the communities of the epiphytic and endophytic microbes in Camellia oleifera, this study assessed three representative C. oleifera cultivars from three areas in Hunan, China by Illumina high-throughput sequencing. The results showed that the diversity and species richness of endophytic microbial community in leaves were significantly higher than those of microbial community in the epiphytic. The diversity and species richness of epiphytic and endophytic microbes are complex when the same cultivar was grown in different areas. The C. oleifera cultivars grown in Youxian had the highest diversity of epiphytic microbial community, but the lowest abundance, while the cultivars grown in Changsha had the highest diversity and species richness of endophytic microbes in leaves. It was concluded that the dominant phylum mainly included Proteobacteria, Actinobacteriota and Firmicutes through the analysis of the epiphytic and endophytic microbial communities of C. oleifera. The species and relative abundances of epiphytic and endophytic microbial community were extremely different at the genus level. The analysis of NMDS map and PERMANOVA shows that the species richness and diversity of microbial communities in epiphytes are greatly influenced by region. However, the community structure of endophytic microorganisms in leaves is influenced by region and cultivated varieties, but the influence of cultivars is more significant. Molecular ecological network analysis showed that the symbiotic interaction of epiphytic microbial community was more complex.

Analysis of differences in microorganisms and aroma profiles between normal and off-flavor pit mud in Chinese strong-flavor Baijiu

The unique cellar fermentation process of CFSB is the reason for its characteristic “cellar aroma” flavor. The types, abundance, community structure and metabolic activity of microorganisms in the pit mud directly affect the microbial balance in the white spirit production environment, promoting the formation of typical aromas and influencing the quality of CFSB. During the production process, the production of off-flavor in the cellar may occur. The aim of this study is to elucidate the differences in microbiota and flavor between normal pit mud and abnormal pit mud (pit mud with off-flavor). A total of 46 major volatile compounds were identified, and 24 bacterial genera and 21 fungal genera were screened. The esters, acids, and alcohols in the abnormal pit mud were lower than those in the normal pit mud, while the aldehydes were higher. Indole, 3-methyl-, which have been proven to be responsible for the muddy and musty flavors, were detected in both types of pit mud, and for the first time, high levels of 4-Methylanisole were detected in the pit mud. The microbial composition of the two types of pit mud showed significant differences in the bacterial genera of Sporosarcina, Lactobacillus, Garciella, Anaerosalibacter, Lentimicrobium, HN-HF0106, Petrimonas, Clostridium_sensu_stricto_12 and Bacillus, and the fungal genera of Millerozyma, Penicillium, Mortierella, Monascus, Saccharomyces, Issatchenkia, Pithoascus, Pseudallescheria, and Wickerhamomyces. While we speculate that Sporosarcina is the predominant bacterial genus responsible for the imbalance of microbiota in pit mud.

Wallace’s line structures seagrass microbiota and is a potential barrier to the dispersal of marine bacteria

BackgroundThe processes that shape microbial biogeography are not well understood, and concepts that apply to macroorganisms, like dispersal barriers, may not affect microorganisms in the same predictable ways. To better understand how known macro-scale biogeographic processes can be applied at micro-scales, we examined seagrass associated microbiota on either side of Wallace’s line to determine the influence of this cryptic dispersal boundary on the community structure of microorganisms. Communities were examined from twelve locations throughout Indonesia on either side of this theoretical line.ResultsWe found significant differences in microbial community structure on either side of this boundary (R2 = 0.09; P = 0.001), and identified seven microbial genera as differentially abundant on either side of the line, six of these were more abundant in the West, with the other more strongly associated with the East. Genera found to be differentially abundant had significantly smaller minimum cell dimensions (GLM: t923 = 59.50, P < 0.001) than the overall community.ConclusionDespite the assumed excellent dispersal ability of microbes, we were able to detect significant differences in community structure on either side of this cryptic biogeographic boundary. Samples from the two closest islands on opposite sides of the line, Bali and Komodo, were more different from each other than either was to its most distant island on the same side. We suggest that limited dispersal across this barrier coupled with habitat differences are primarily responsible for the patterns observed. The cryptic processes that drive macroorganism community divergence across this region may also play a role in the bigeographic patterns of microbiota.

Response of Phyllosphere and Rhizosphere Microbial Communities to Salt Stress of Tamarix chinensis.

As carriers of direct contact between plants and the atmospheric environment, the microbiomes of phyllosphere microorganisms are increasingly recognized as an important area of study. Salt secretion triggered by salt-secreting halophytes elicits changes in the community structure and functions of phyllosphere microorganisms, and often provides positive feedback to the individual plant/community environment. In this study, the contents of Na+ and K+ in the rhizosphere, plant and phyllosphere of Tamarix chinensis were increased under 200 mmol/L NaCl stress. The increase in electrical conductivity, Na+ and K+ in the phyllosphere not only decreased the diversity of bacterial and fungal communities, but also decreased the relative abundance of Actinobacteriota and Basidiomycota. Influenced by electrical conductivity and Na+, the bacteria-fungus co-occurrence network under salt stress has higher complexity. Changes in the structure of the phyllosphere microbial community further resulted in a significant increase in the relative abundance of the bacterial energy source and fungal pathotrophic groups. The relative abundance of Actinobacteriota and Acidobacteriota in rhizosphere showed a decreasing trend under salt stress, while the complexity of the rhizosphere co-occurrence network was higher than that of the control. In addition, the relative abundances of functional groups of rhizosphere bacteria in the carbon cycle and phosphorus cycle increased significantly under stress, and were significantly correlated with electrical conductivity and Na+. This study investigated the effects of salinity on the structure and physicochemical properties of phyllosphere and rhizosphere microbial communities of halophytes, and highlights the role of phyllosphere microbes as ecological indicators in plant responses to stressful environments.

Powdery mildew-induced changes in phyllosphere microbial community dynamics of cucumber.

As an important habitat for microorganisms, the phyllosphere has a great impact on plant growth and health, and changes in phyllosphere microorganisms are closely related to the occurrence of leaf diseases. However, there remains a limited understanding regarding alterations to the microbial community in the phyllosphere resulting from pathogen infections. Here, we analyzed and compared the differences in phyllosphere microorganisms of powdery mildew cucumber from three disease severity levels (0% < L1 < 30%, 30% ≤ L2 < 50%, L3 ≥ 50%, the number represents the lesion coverage rate of powdery mildew on leaves). There were significant differences in α diversity and community structure of phyllosphere communities under different disease levels. Disease severity altered the community structure of phyllosphere microorganisms, Rosenbergiella, Rickettsia, and Cladosporium accounted for the largest proportion in the L1 disease grade, while Bacillus, Pantoea, Kocuria, and Podosphaera had the highest relative abundance in the L3 disease grade. The co-occurrence network analysis of the phyllosphere microbial community indicated that the phyllosphere bacterial community was most affected by the severity of disease. Our results suggested that with the development of cucumber powdery mildew, the symbiotic relationship between species was broken, and the entire bacterial community tended to compete.

Metagenomics reveals the response of desert steppe microbial communities and carbon-nitrogen cycling functional genes to nitrogen deposition.

Nitrogen (N) deposition seriously affects the function of carbon (C) and N cycling in terrestrial ecosystems by altering soil microbial communities, especially in desert steppe ecosystems. However, there is a need for a comprehensive understanding of how microorganisms involved in each C and N cycle process respond to N deposition. In this study, shotgun metagenome sequencing was used to investigate variations in soil C and N cycling-related genes in the desert steppe in northern China after 6 years of the following N deposition: N0 (control); N30 (N addition 30 kg ha-1 year-1): N50 (N addition 50 kg ha-1 year-1). N deposition significantly increased the relative abundance of Actinobacteria (P < 0.05) while significantly decreased the relative abundances of Proteobacteria and Acidobacteria (P < 0.05). This significantly impacted the microbial community composition in desert steppe soils. The annual addition or deposition of 50 kg ha-1 year-1 for up to 6 years did not affect the C cycle gene abundance but changed the C cycle-related microorganism community structure. The process of the N cycle in the desert steppe was affected by N deposition (50 kg ha-1 year-1), which increased the abundance of the pmoA-amoA gene related to nitrification and the nirB gene associated with assimilation nitrite reductase. There may be a niche overlap between microorganisms involved in the same C and N cycling processes. This study provides new insights into the effects of N deposition on soil microbial communities and functions in desert steppe and a better understanding of the ecological consequences of anthropogenic N addition.

Exploring the microbial ecosystem of Berchemia polyphylla var. leioclada: a comprehensive analysis of endophytes and rhizospheric soil microorganisms.

Endophytic and rhizospheric microorganisms associated with plants play a crucial role in plant health, pest and disease defense, and fruit yield by actively participating in the plant's adaptation to its environment. In this study, high-throughput sequencing technology was employed to analyze the community structure and diversity of endophytic and rhizospheric soil microorganisms in Berchemia polyphylla var. leioclada. The results revealed significant differences in microbial diversity and community structure between the soil and plant compartments within the same geographic region. Microbial diversity and species composition varied among different geographic locations. The dominant bacteria in plants were Cyanobacteria and Proteobacteria, with dominant genera including Methylobacterium-Methylorubrum, Escherichia-Shigella and Sphingomonas. In contrast, the dominant bacteria in soil were Proteobacteria, Acidobacteriota, and Actinobacteriota, with dominant genera such as Sphingomonas, Conexibacter and Vicinamibacteraceae, with Sphingomonas was considered core groups present in all plant and soil samples. As for fungi, the dominant phyla in both plants and soil were Ascomycota, Basidiomycota, and Mortierellomycota, with different dominant genera between the two compartments, including Fusarium, Septoria, and Mortierella, totaling 59 genera. Linear discriminant analysis at the genus level identified 102 bacterial and 54 fungal indicator taxa associated with plants and soil. Co-occurrence network analysis indicated close interactions among soil bacterial microorganisms. Functional prediction of the top 10 microbial genes revealed three bacterial metabolic pathways shared between soil and plants, while the predominant fungal metabolic types were similar between the two compartments but with varying abundances. This study elucidates the diversity and interplay of endophytic and rhizospheric microorganisms in Berchemia polyphylla var. leioclada across diverse geographical regions, providing insights crucial for the plant's conservation and development.

Activity and community structure of nitrifiers and denitrifiers in nitrogen-polluted rivers along a latitudinal gradient

Nitrogen (N) cycling in rivers is particularly active and dynamic due to excess nutrient inputs worldwide. However, the multidimensional spatial patterns of the activity and community structure of N-cycling microorganisms in rivers remain unclear, limiting our understanding of river ecological functions, especially N removal capacity. Here, we measured the nitrification and denitrification rates and identified nitrifying and denitrifying microorganisms using high-throughput sequencing of archaeal amoA, bacterial amoA, nirK, and nirS genes in channel sediments, riparian rhizosphere soils, and riparian bulk soils of 30 N-polluted rivers across China. Results showed that in the lateral dimension, nitrification rates in sediments did not differ significantly from those in rhizosphere and bulk soils, but denitrification rates were higher in sediments than in bulk soils. However, the archaeal amoA gene abundance in sediments was considerably lower than that in rhizosphere and bulk soils, and bacterial amoA gene abundance in sediments was greater than that in rhizosphere soils. In the vertical dimension, both nitrification and denitrification rates in riparian bulk soils decreased with soil depth, and topsoils harbored more nitrifying and denitrifying microbes than subsoils. Denitrification but not nitrification rates increased with latitude and altitude but decreased with increasing mean annual temperature and precipitation. Overall, these results provide new insights into the multidimensional spatial patterns of river N cycling at a large scale, which is crucial to evaluating the N removal function of global rivers.

Recovery of 1887 metagenome-assembled genomes from the South China Sea

The South China Sea (SCS) is a marginal sea characterized by strong land-sea biogeochemical interactions. SCS has a distinctive landscape with a multitude of seamounts in its basin. Seamounts create “seamount effects” that influence the diversity and distribution of planktonic microorganisms in the surrounding oligotrophic waters. Although the vertical distribution and community structure of marine microorganisms have been explored in certain regions of the global ocean, there is a lack of comprehensive microbial genomic surveys for uncultured microorganisms in SCS, particularly in the seamount regions. Here, we employed a metagenomic approach to study the uncultured microbial communities sampled from the Xianbei seamount region to the North Coast waters of SCS. A total of 1887 non-redundant prokaryotic metagenome-assembled genomes (MAGs) were reconstructed, of which, 153 MAGs were classified as high-quality MAGs based on the MIMAG standards. The community structure and genomic information provided by this dataset could be used to analyze microbial distribution and metabolism in the SCS.

The phoD-Harboring Microorganism Communities and Networks in Karst and Non-Karst Forests in Southwest China

Phosphorous (P) limitation is common not only in tropical rainforest and savanna ecosystems, but also in karst forest ecosystems. Soil phoD-harboring microorganisms are essential in soil P cycles, but very little information is available about them in karst ecosystems. A total of 36 soil samples were collected from two types of forest ecosystems (karst and non-karst) over two seasons (rainy and dry), and the diversity and community structure of soil phoD-harboring microorganisms were measured. The contents of available P (AP), soil total P (TP), microbial biomass P (MBP) and the activity of alkaline phosphatase (ALP) in karst forest soils were higher than those in non-karst forest soils, whereas the contents of CaCl2-P, citrate-P, enzyme-P and the activity of acid phosphatase (ACP) were the opposite. Soil AP content was significantly higher in the rainy season than in the dry season, whereas ALP activity was the opposite. The community structure of phoD-harboring microorganisms was more influenced by forest-type than season. The network connectivity was higher in non-karst forests than in karst forests. Two dominant orders, Burkholderiales and Rhizobiales, were the keystone taxa in these networks in two forests, and their relative abundances were higher in non-karst forests than in karst forests. The microorganic diversity indices (e.g., Shannon–Wiener, Evenness, Richness, and Chao1) were substantially higher in karst than in non-karst forests. These indices were positively correlated with the contents of SOC and TN in the two forests; meanwhile, richness and evenness indices were positively correlated with citrate-P, HCl-P, and TP in non-karst forests. Structural equation modelling results showed that the relative abundance of phoD-harboring microorganisms was mainly influenced by pH and AP, with direct affection of soil AP, pH, and ALP activity, and indirect affection of ALP activity through affecting AP. These findings highlight that the P cycle is mainly regulated by the diversity of phoD-harboring microorganisms in karst forest ecosystems, whereas it is mainly regulated by dominant taxa in non-karst forest ecosystems. In future, regulating the interaction networks and keystone taxa of phoD-harboring microorganisms may be critical to alleviating P limitations in karst forest ecosystems.

Responses of microbial communities subjected to hydrodynamically induced disturbances in an organic contaminated site

Organic contaminated sites have gained significant attention as a prominent contributor to shallow groundwater contamination. However, limited knowledge exists regarding the impact of hydrodynamic effects on microbially mediated contaminant degradation at such sites. In this study, we investigated the distribution characteristics and community structure of prokaryotic microorganisms at the selected site during both wet and dry seasons, with a particular focus on their environmental adaptations. The results revealed significant seasonal variations (P < 0.05) in the α-diversity of prokaryotes within groundwater. The dry season showed more exclusive OTUs than the wet season. The response of prokaryotic metabolism to organic pollution pressure in different seasons was explored by PICRUSt2, and enzymes associated with the degradation of organic pollutants were identified based on the predicted functions. The results showed that hormesis was considered as an adaptive response of microbial communities under pollution stress. In addition, structural equation models demonstrated that groundwater level fluctuations can, directly and indirectly, affect the abundance and diversity of prokaryotes through other factors such as oxidation reduction potential (ORP), dissolved oxygen (DO), and naphthalene (Nap). Overall, our findings imply that the taxonomic composition and functional properties of prokaryotes in groundwater in organic contaminated sites is influenced by the interaction between seasonal variations and characteristics of organic pollution. The results provide new insights into microbiological processes in groundwater systems in organic contaminated sites.

Effects of Different Proportions of Organic Fertilizer in Place of Chemical Fertilizer on Microbial Diversity and Community Structure of Pineapple Rhizosphere Soil

With the development of sustainable agriculture, the application of organic fertilizers to crops instead of chemical fertilizers has become an inevitable trend. However, little is known about the proportion of organic fertilizers replacing chemical fertilizers and how it affects the underlying microbial mechanisms of continuous pineapple soil. In this study, we used the Illumina Miseq high-throughput sequencing platform to study the rhizosphere soil of continuously cropped pineapples to study the diversity and community structure of pineapple rhizosphere microorganisms. The results showed that, with 97% similarity, the number of OTUs of all samples obtained using hierarchical clustering analysis is 3645. Both conventional fertilization (CF) and optimal fertilization (YF) increased the relative abundance of Proteobacteria, Actinomycetes, and Sclericutes, and decreased the relative abundance of Acidobacteria, Bacteroidetes, Blastomonas, and Verrucobacteria. The replacement of organic fertilizers increased the relative abundance of Bacteroidetes, among which the relative abundance of chlorocurvus treated with the replacement of organic fertilizers of 80% was the highest. Different fertilization methods also changed the diversity and abundance of bacteria in the soil of the pineapple rhizosphere; the diversity of the species was E &gt; D &gt; C &gt; CK &gt; B &gt; YF &gt; CF. Based on the analysis of the PCoA and NMDS of soil bacterial communities, treatment E was similar to treatment D, treatment CK was similar to treatment YF, and treatment C and treatment D had little structural difference. On the basis of an analysis of the composition and function of the flora, it can be found that different fertilization methods have significant differences in the bacterial groups of the rhizosphere bacterial community of pineapple soil. The relative abundance of beneficial bacteria was increased. When organic fertilizer replaces chemical fertilizer, it promotes the role of bacteria related to the carbon cycle in the rhizosphere.

Dynamic Response of the cbbL Carbon Sequestration Microbial Community to Wetland Type in Qinghai Lake.

The soil carbon storage in the Qinghai-Tibet Plateau wetlands is affected by microbiota and wetland types, but the response mechanisms of carbon sequestration microorganisms on the Qinghai-Tibet Plateau to different wetland types are still poorly described. To explore the differences in carbon sequestration microbial communities in different wetlands and the main influencing factors, this study took a marsh wetland, river source wetland and lakeside wetland of Qinghai Lake as the research objects and used high-throughput sequencing to study the functional gene, cbbL, of carbon sequestration microorganisms. The results showed that the dominant bacterial group of carbon sequestration microorganisms in marsh and river source wetlands was Proteobacteria, and the dominant bacterial group in the lakeside wetland was Cyanobacteria. The alpha diversity, relative abundance of Proteobacteria and total carbon content were the highest in the marsh wetland, followed by the river source wetland, and they were the lowest in the lakeside wetland. In addition, the physical and chemical characteristics of the three wetland types were significantly different, and the soil temperature and moisture and total carbon content were the most important factors affecting the community structures of carbon-sequestering microorganisms. There was little difference in the total nitrogen contents between the marsh wetland and river source wetland. However, the total nitrogen content was also an important factor affecting the diversity of the carbon sequestration microbial community. In summary, the wetland type significantly affects the process of soil carbon sequestration. Compared with the riverhead and lakeside wetlands, the marsh wetland has the highest carbon storage.

Effects of repeated afidopyropen treatment on the structure and function of the soil microbial community

Chemical insecticides are the most effective pest control agents. Afidopyropen is a novel insecticide used against sap-sucking insects, such as aphids. However, the effects of repeated afidopyropen application on the structure and function of soil microorganisms remain unknown. In this study, the changes in the enzyme activities, community structure and function, and relative abundance of antibiotic resistance ontology (ARO) of soil microorganisms were investigated during three repeated afidopyropen applications under laboratory conditions at the maximum recommended dosage (M1) and 10 times the M1 (M10). The neutral phosphatase (NPA) and catalase (CAT) activities in the soil were significantly suppressed after afidopyropen treatment. The Simpson diversity index (1/D) and Shannon–Wiener diversity index (H) also decreased in both the M1 and M10 afidopyropen-treated soils, indicating a remarkable decrease in soil microorganism diversity. The average well color development (AWCD) first increased and subsequently recovered to normal levels after the third application of the insecticide, suggesting that afidopyropen application could increase the metabolic activity of soil microorganisms. Metagenomic analysis showed that repeated afidopyropen application in both the M1 and M10 treatment groups altered the community structure of soil microorganisms, albeit in different ways. Furthermore, repeated afidopyropen application significantly increased the relative ARO abundance, especially in the M10 treatment, with the most dominant AROs being adeF, baeS, and IND-6. These findings reveal the effects of excessive afidopyropen application on soil microorganisms and lay an important foundation for the comprehensive evaluation of the impact of this insecticide on the environment.

Temperate grassland soil nitrifiers are more sensitive to nitrogen addition than simulated warming

Soil nitrogen transformations are influenced by both global climate change and human activities. Nitrification, affected by ammonia-oxidizing and nitrite-oxidizing microorganisms, is one of the crucial N transformation processes. However, the impact of environmental change on the diversity and community structure of these microorganisms in grassland ecosystems remains poorly understood. This study explored the alpha diversity and community structures of N-cycling microorganisms in response to simulated warming and N addition in a temperate steppe. The results showed that N addition significantly increased the taxon richness of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria but significantly decreased the diversity of total archaea. Also, N addition significantly changed the community structures of ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, and total archaea and bacteria. However, warming had no effect on the whole microbiome alpha and beta diversity. The alternations of microbial communities were mainly induced by changes in soil pH and inorganic N concentrations. This study illustrates that the temperate grassland microbial communities are more sensitive to N addition than simulated warming under future climate change scenes.