Community Structure Of Soil Microorganisms Research Articles

Community structure of soil microorganisms and endophytes of honeysuckle at different ecological niche specificities

BackgroundThe plant microbiome is one of the key determinants of healthy plant growth. However, the complexity of microbial diversity in plant microenvironments in different regions, especially the relationship between subsurface and aboveground microorganisms, is not fully understood. The present study investigated the diversity of soil microorganisms in different regions and the diversity of microorganisms within different ecological niches, and compared soil microorganisms and endophytic microorganisms.Methods16 S and ITS sequencing was used to sequence the soil and endophytes microbiome of honeysuckle. Alpha diversity analysis and principal component analysis (PCoA) were used to study the soil and endophyte microbial communities, and the function of endophyte bacteria and fungi was predicted based on the PICRUST2 process and FUNGuild.ResultsIn total, there were 382 common bacterial genera and 139 common fungal genera in the soil of different producing areas of honeysuckle. There were 398 common bacterial genera and 157 common fungal genera in rhizosphere soil. More beneficial bacteria were enriched in rhizosphere soil. Endophytic bacteria were classified into 34 phyla and 770 genera. Endophytic fungi were classified into 11 phyla and 581 genera, among which there were significant differences in the dominant genera of roots, stems, leaves, and flowers, as well as in community diversity and richness. Endophytic fungal functions were mainly dominated by genes related to saprophytes, functional genes that could fight microorganisms were also found in KEGG secondary functional genes.ConclusionMore beneficial bacteria were enriched in rhizosphere soil of honeysuckle, and the microbial network of the rhizosphere is more complex than that of the soil. Among the tissues of honeysuckle, the flowers have the richest diversity of endophytes. The endogenous dominant core bacteria in each part of honeysuckle plant have a high degree of overlap with the dominant bacteria in soil. Functional prediction suggested that some dominant core bacteria have antibacterial effects, providing a reference for further exploring the strains with antibacterial function of honeysuckle. Understanding the interaction between honeysuckle and microorganisms lays a foundation for the study of growth promotion, quality improvement, and disease and pests control of honeysuckle from the perspective of microorganisms.

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.

Biochar's Influence on Soil Microorganisms: Understanding the Impacts and Mechanisms

Biochar, the carbon-rich material produced from biomass pyrolysis, has garnered significant attention and research interest owing to its myriad of potential benefits for soil enhancement. These benefits range from increasing soil carbon storage, boosting soil fertility, to transforming and fixing pollutants in soil, all of which serve to ameliorate the overall soil environment. The impact of these improvements extends to the metabolic activities and community structure of soil microorganisms, either directly or indirectly, creating ripple effects on soil health. This paper embarks on a thorough review of biochar's effects on various soil aspects. These include the soil's physicochemical properties, such as its structure, composition, and reaction properties, and how biochar can influence these to improve the soil environment. It also explores how biochar affects enzyme activities in the soil that are crucial for various biochemical processes, as well as nutrients vital for plant growth and development. Importantly, the ability of biochar to interact with contaminants, rendering them harmless or less toxic, is examined, alongside an investigation into the related microbial activities that are influenced by these changes. This work also aims to summarise the potential mechanisms of interaction between biochar and microorganisms, providing a clearer understanding of how biochar influences the soil microbiome. It discusses the potential risks associated with biochar use, such as the release of harmful substances or unintended shifts in microbial communities, emphasizing the importance of a balanced view towards biochar application. Overall, the aim of this study is to lay a robust theoretical groundwork for future research in this field, contributing towards a better understanding and utilisation of biochar for soil enhancement and sustainable agriculture.

Rhizobium Soaking Promoted Maize Growth by Altering Rhizosphere Microbiomes and Associated Functional Genes.

Rhizobium is a Gram-negative bacterium, which dissolves minerals, produces growth hormones, promotes root growth, and protects plants from different soil-borne pathogens. In the present study, roots, stalks, and fresh weight of maize (Zea mays L.) were significantly increased after soaking in Bradyrhizobium japonicum compared with the control. Subsequently, transcriptome sequencing results of the whole maize plant soaked in B. japonicum showed that multiple growth and development-related genes were up-regulated more than 100-fold compared to the control. Furthermore, the abundance of plant growth promoting bacteria, such as Acidobacteria Subgroup_6 and Chloroflexi KD4-96, were increased significantly. On the contrary, the abundance of multiple pathogens, such as Curvularia, Fusarium and Mycocentrospora, were significantly decreased. Moreover, inoculation with B. japonicum could inhibit the infection of the pathogen Fusarium graminearum in maize. These results suggest that soaking seeds in B. japonicum may affect the expression of maize growth and development-related genes as the bacteria changes the soil microorganism community structure. These findings may help to expand the application of B. japonicum in crop production and provide new opportunities for food security.

Effects of wildfire disturbance on forest soil microbes and colonization of ericoid mycorrhizal fungi in northern China

Wildfires affect forest succession and restoration by changing the community structure of soil microorganisms. Mycorrhizal formation is essential for plant growth and development. However, the driving mechanism of their natural succession after wildfire is still unclear. In this study, we examined the community structure of soil bacteria and fungi along a time series of natural recovery after wildfires in the Greater Khingan Range of China (2020 fires, 2017 fires, 2012 fires, 2004 fires, 1991 fires, and unburned). By exploring the effects of wildfire on plant traits, fruit nutrition, colonization of mycorrhizal fungi and its influencing mechanism. The results show that natural succession after wildfires significantly changed the community composition of bacteria and fungi, with β diversity having a greater impact but less impact on the α diversity of microorganisms. Wildfires significantly changed plant traits and fruit nutrient content. The changes in colonization rate and customization intensity of mycorrhizal fungi were caused by increased MDA content and soluble sugar content and increased MADS-box gene and DREB1 gene expression in lingonberry (Vaccinium vitis-idaea L.). Our results showed that the soil bacterial and fungal communities in the boreal forest ecosystem changed significantly during wildfire recovery and changed the colonization rate of lingonberry mycorrhizal fungi. This study provides a theoretical basis for the restoration of forest ecosystems after wildfires.

Allelopathic Effects of Amomum villosum Lour. Volatiles from Different Organs on Selected Plant Species and Soil Microbiota.

Amomum villosum Lour. is a perennial herb of the Zingiberaceae family, which is widely distributed in Xishuangbanna, Yunnan Province in Southwest China. Large amounts of volatile components contained in this plant enter the surrounding atmosphere and soil through volatilization, foliar leaching, root exudation, and residue decomposition. However, the ecological role of these compounds is currently unclear. The aim of this study was to compare the differences in the composition of volatile oils from stems, leaves, and young fruits of A. villosum, identify chemicals that had allelopathic effects, and explore the effects of the oil on the diversity and composition of soil microbiomes. Volatile oils were obtained by steam distillation and characterized by gas chromatography−mass spectrometry, and then were tested for allelopathic activity using seedlings of Lactuca sativa L. and Lolium perenne L. as test species. The results showed that the oils from stems and leaves were rich in monoterpene hydrocarbons, unlike the oxygenated monoterpenes which dominated oils from young fruits. Leaves > stems > young fruits: this was the order of the allelopathic effects of volatile oils from various A. villosum organs. Among the four main chemical components in the oils, only α-pinene, which is abundant in leaves, had a stronger allelopathic action than the crude oils, implying that it might be a potential allelochemical. Experiments on soil microorganisms indicated that 3.0 mg/mL oil had the greatest effect on the structure of the soil fungal community. It can be concluded that A. villosum is capable of releasing allelochemicals which affect the growth of other plant species and the diversity and community structure of soil microorganisms.

Soil microbial diversity and functional capacity associated with the production of edible mushroom Stropharia rugosoannulata in croplands.

In recent years, a rare edible mushroom Stropharia rugosoannulata has become popular. S. rugosoannulata has the characteristics of easy cultivation, low cost, high output value, and low labor requirement, making its economic benefits significantly superior to those of other planting industries. Accumulating research demonstrates that cultivating edible fungus is advantageous for farming soil. The present experiment used idle croplands in winter for S. rugosoannulata cultivation. We explored the effects of S. rugosoannulata cultivation on soil properties and soil microbial community structure in paddy and dry fields, respectively. We cultivated S. rugosoannulata in the fields after planting chili and rice, respectively. The results showed that Chili-S. rugosoannulata and Rice-S. rugosoannulata planting patterns increased the yield, quality and amino acid content of S. rugosoannulata. By analyzing the soil properties, we found that the Chili-S. rugosoannulata and Rice-S. rugosoannulata cropping patterns increased the total nitrogen, available phosphorus, soil organic carbon, and available potassium content of the soil. We used 16s amplicons for bacteria and internal transcribed spacer (ITS) region for fungi to analyze the microbial communities in rhizosphere soils. Notably, S. rugosoannulata cultivation significantly increased the abundance of beneficial microorganisms such as Chloroflexi, Cladosporium and Mortierella and reduce the abundance of Botryotrichumin and Archaeorhizomyces. We consider S. rugosoannulata cultivation in cropland can improve soil properties, regulate the community structure of soil microorganisms, increase the expression abundance of beneficial organisms and ultimately improve the S. rugosoannulata yield and lay a good foundation for a new round of crops after this edible mushroom cultivation.

Effect of vegetable residues incorporation on soil fertility, rhizosphere microbial community structure, and plant growth of continuously cropped cucumber in a solar greenhouse

PurposeIncorporating crop residues into the soil is considered a sustainable and valuable method to alleviate soil deterioration caused by continuous monoculture in greenhouse production. However, the effect of vegetable residues retention on soil amendments is poorly understood. In the present study, we investigated the impacts of sweet pepper, tomato, and cucumber plant residues on soil microbial communities and plant growth of continuously cropped cucumber in a solar greenhouse.MethodsThe 16S rRNA and ITS1 rRNA genes were amplified, and high-throughput sequencing was performed to explore the impacts of vegetable residues incorporation on soil microbial communities. Additionally, soil chemical properties, cucumber root vigor, and fruit yield were measured to assess the impacts of vegetable residues incorporation on continuously cropped soil and cucumber growth.ResultsThe results showed that incorporating vegetable residues could improve soil buffering capacity, increase the content of soil organic matter and available nutrients, and increased the diversity of soil microorganisms and improved community structure; vegetable residues increased the abundance of beneficial bacteria such as Actinobacteria, Firmicutes, Proteobacteria, and Chloroflexi, while reducing the quantity of soil-borne pathogens such as Bacillariophyta and Acidobacteria. Similar results were observed for the fungal communities: the relative abundance of Ascomycota was decreased to varying degrees, while the relative abundance of Rozellomycota and Basidiomycota was raised. The results demonstrated that vegetable residues incorporation significantly increased cucumber root vigor and enhanced fruit yield. The effects of different types of residues on improving soil properties were ordered sweet pepper plant residues > cucumber plant residues > tomato plant residues, and 20% of sweet pepper plant residues incorporation had the most significant effect on crop yield.ConclusionIn summary, returning vegetable residues alleviated soil continuous cropping obstacles by improving the soil fertility and the diversity and community structure of soil microorganisms, and consequently promoting the growth and yield of greenhouse-grown cucumbers. The findings demonstrated that returning vegetable residues was an effective and sustainable measure for soil amendment during continuous cropping in greenhouse production.

Soil bacterial community responses to cadmium and lead stabilization during ecological restoration of an abandoned mine

AbstractEcological restoration refers to the gradual recovery of damaged ecosystems by utilizing their self‐recovery capacity and artificial measures. It is considered as an effective technique to alleviate heavy metal pollution in open‐pit mining soils. However, little is known about the stability of heavy metals and soil bacterial responses in artificially restored soil‐plant systems. In this study, different vegetation restoration strategies were established in the Dabaoshan mining area, China, and the accumulation and transfer of Cd/Pb in the soil‐plant system and the responses of the soil bacterial community were investigated. Results showed that ecological restoration with a combination of trees, shrubs and grasses/herbs could increase soil cation‐exchange capacity and organic matter content, but not soil pH. The mixture of trees, shrubs and grasses/herbs was most effective for reducing the available Pb content to 33.7% of the content in the control, and the mixture of trees and grasses/herbs was beneficial in reducing Cd to 60.4% of the content in the control. Data showed that ecological restoration could change the quantity, composition and community structure of soil microorganisms. The soils in which a mixture of trees, shrubs and grasses/herbs were grown had the greatest abundance and diversity of bacteria; the abundances of Proteobacteria increased by 12% and Actinobacteria by 5% from those of the control. Plant coverage, soil available Cd content, and organic matter emerged as major determinants of bacterial community composition. This study demonstrates a promising remediation strategy for limiting Cd/Pb mobility in mining areas.

Application of humic acid compound fertilizer for increasing sweet potato yield and improving the soil fertility

Combined application of humic acid (HA) and multi-nutrient fertilizer improve nutrient utilization and increase crop yield. To give insight about the application of HA compound fertilizer in sweet potato production, a field experiment was conducted the effect of humic acid-nitrogen, phosphorus, and potassium compound fertilizer (HA-NPK) on soil nutrient contents, soil enzyme activity, soil microorganism community structure and yield of sweet potato. Results showed that compared to nitrogen, phosphorus, and potassium compound fertilizer (NPK) treatment, the activated humic acid- nitrogen, phosphorus, and potassium compound fertilizer (HA-NPK1) and non-activated humic acid- nitrogen, phosphorus, and potassium compound fertilizer (HA-NPK2) treatment significantly increased the plant biomass and storage root yield. Increase in yield from application of HA-NPK1 was significantly larger than those from HA-NPK2. The HA-NPK1 treatment greatly increased the content of readily available phosphorus, potassium and soil organic matter, enhanced the enzyme activity of soil urease, invertase, alkaline phosphatase and catalase. The numbers of soil bacteria, fungi and actinomycetes in the HA-NPK1 treatment were significantly higher than the NPK treatment. In conclusion, the application of the activated HA-NPK in sweet potato production could be used effectively to increase soil quality, facilitate the growth of sweet potato and increase its yield under similar conditions to this work.

Oil degradation and variation of microbial communities in contaminated soils induced by different bacterivorous nematodes species

Oil pollution poses a great threat to environments and makes the remediation of oil-contaminated soils an urgent task. Microorganisms are the main biological factor for oil removal in the environment but microbial remediation is greatly affected by environmental factors. For our research, we inoculated three species of bacterivorous nematodes into oil-contaminated soil to explore how bacterivorous nematodes affect soil microbial activities and community structure in contaminated soil, as well as how efficiently different nematodes remove oil pollution from the soil. Six treatments were set in this experiment: sterilized oil-contaminated soil (SOC); nematode-free soil (S); oil-contaminated soil (OC); oil-contaminated soil + Caenorhabditis elegans (OCN1); oil-contaminated soil + Cephalobus persegnis (OCN2); oil-contaminated soil + Rhabditis marina (OCN3) for a 168-day incubation experiment. After the experiment was done, the oil contents in SOC, OC, OCN1, OCN2, and OCN3 were reduced by 6.5%, 32.3%, 38.2%, 42.8%, and 40.2%, respectively, compared with the beginning of the experiment. The amount of phospholipid fatty acids (PLFAs) of Gram-negative bacteria in OC, OCN1, OCN2, and OCN3 was increased by 50.9%, 43.4%, 37.7%, and 47.9%, respectively, compared with that of S. During the 168-day incubation period, the maximum growth of the number of nematodes in OCN1, OCN2, and OCN3 compared with the initial number of the nematodes were 2.25-, 1.52-, and 1.65-fold, respectively. The amount of oil residue in the contaminated soil negatively correlated with the populations of nematodes, total microorganisms, Gram-negative bacteria, actinomycetes, and eukaryotes. Thus, oil pollution increased the number of Gram-negative bacteria, decreased the ratio of Gram-positive bacteria/Gram-negative bacteria and Fungi/Bacteria significantly, and altered the community structure of soil microorganisms. Each species of bacterivorous nematodes has got its unique effect on the microbial activity and community structure in oil contaminated soils, but those tested can promote oil degradation and thus improve the environment of oil contaminated soils.

Periphyton improves soil conditions and offers a suitable environment for rice growth in coastal saline alkali soil

AbstractPeriphyton plays an indispensable role in coastal saline‐alkali land, but its function is poorly understood. Soil physical and chemical properties (pH value, salinity, soil organic matter), enzyme activity, and microbial diversity (based on 16 s rDNA, ITS and functional genes) were measured in periphyton formed on rice‐growing coastal saline‐alkali soil modified by a new type of soil conditioner. The results showed that the content of organic matter and catalase activity in periphyton were significantly higher than in the unplanted control soil. Soil pH and salinity were decreased in periphyton compared to the unplanted control soil. Based on the relative abundance, bacterial genera Desulfomicrobium, Rhodobacter, cyanobacterium_scsio_T−2, Gemmatimonas, and Salinarimonas as well as fungal genus Fusarium were more abundant in periphyton than the unplanted control soil. In terms of functional genes, the cbbM and cbbL sequencing showed higher abundance of Hydrogenophaga, Rhodovulum, Magnetospira, Leptothrix, and Thiohalorhabdus, whereas the nifH sequencing indicated higher abundance of Cyanobacteria in the periphyton compared to the unplanted soil. The relative abundance and community structure of soil microorganisms were improved by periphyton, thus reducing soil salinity and pH, and increasing soil organic matter and enzyme activity. This indicated that the periphyton can improve the conditions and offer a suitable environment for plant growth in coastal saline‐alkali soil.

Interactive Effects of Scion and Rootstock Genotypes on the Root Microbiome of Grapevines (Vitis spp. L.)

Diversity and community structure of soil microorganisms are increasingly recognized as important contributors to sustainable agriculture and plant health. In viticulture, grapevine scion cultivars are grafted onto rootstocks to reduce the incidence of the grapevine pest phylloxera. However, it is unknown to what extent this practice influences root-associated microbial communities. A field survey of bacteria in soil surrounding the roots (rhizosphere) of 4 cultivars × 4 rootstock combinations was conducted to determine whether rootstock and cultivar genotypes are important drivers of rhizosphere community diversity and composition. Differences in α-diversity was highly dependent on rootstock–cultivar combinations, while bacterial community structure primarily clustered according to cultivar differences, followed by differences in rootstocks. Twenty-four bacterial indicator genera were significantly more abundant in one or more cultivars, while only thirteen were found to be specifically associated with one or more rootstock genotypes, but there was little overlap between cultivar and rootstock indicator genera. Bacterial diversity in grafted grapevines was affected by both cultivar and rootstock identity, but this effect was dependent on which diversity measure was being examined (i.e., α- or β-diversity) and specific rootstock–cultivar combinations. These findings could have functional implications, for instance, if specific combinations varied in their ability to attract beneficial microbial taxa which can control pathogens and/or assist plant performance.

Effects of Spartina alterniflora Invasion on Soil Microbial Community Structure and Ecological Functions.

It has been reported that the invasion of Spartina alterniflora changed the soil microbial community in the mangrove ecosystem in China, especially the bacterial community, although the response of soil fungal communities and soil microbial ecological functions to the invasion of Spartina alterniflora remains unclear. In this study, we selected three different communities (i.e., Spartina alterniflora community (SC), Spartina alterniflora–mangrove mixed community (TC), and mangrove community (MC)) in the Zhangjiangkou Mangrove Nature Reserve in China. High-throughput sequencing technology was used to analyze the impact of Spartina alterniflora invasion on mangrove soil microbial communities. Our results indicate that the invasion of Spartina alterniflora does not cause significant changes in microbial diversity, but it can alter the community structure of soil bacteria. The results of the LEfSe (LDA Effect Size) analysis show that the relative abundance of some bacterial taxa is not significantly different between the MC and SC communities, but different changes have occurred during the invasion process (i.e., TC community). Different from the results of the bacterial community, the invasion of Spartina alterniflora only cause a significant increase in few fungal taxa during the invasion process, and these taxa are at some lower levels (such as family, genus, and species) and classified into the phylum Ascomycota. Although the invasion of Spartina alterniflora changes the taxa with certain ecological functions, it may not change the potential ecological functions of soil microorganisms (i.e., the potential metabolic pathways of bacteria, nutritional patterns, and fungal associations). In general, the invasion of Spartina alterniflora changes the community structure of soil microorganisms, but it may not affect the potential ecological functions of soil microorganisms.

Soil bacterial and fungal communities and associated nutrient cycling in relation to rice cultivation history after reclamation of natural wetland

AbstractThe reclamation and utilization of natural wetlands can affect the community structure of soil microorganisms. However, knowledge regarding succession of microbial communities during long‐term reclamation and the links with related nutrient cycles is still limited. Using Illumina sequencing, we identified the patterns and environmental drivers of soil bacterial and fungal succession along a 150‐year chronosequence of paddy fields. Soil enzyme activities were determined to characterize functions related to C, N, and P cycles. The results showed that reclamation activity and its history have greatly altered the bacterial community structure and the bacterial groups. This change being mainly reflected in the bacterial genera Halomonas, genera Isosphaera, and family Planctomycetaceae. The change of fungal community was mainly apparent between natural wetlands and paddy fields, manifested as an increase in the classes Sordariomycetes and Dothideomycetes and a significant decrease inthe class Agaricomycetes in paddy fields compared with natural wetland. Compared with fungi, bacteria were more strongly affected by soil chemical nutrient properties and physical properties. Furthermore, the structural equation model indicated that both bacterial and fungal community structure and diversity had a great influence on the C, N, and P cycles. In summary, the bacterial community was more sensitive throughout the history of rice cultivation after reclamation than the fungal community, but both bacteria and fungi may play major roles in soil ecological functions. These findings contribute to the understanding of ecosystem functional mechanisms, which provides a new perspective for the management of natural wetlands.

Mixing of plant litters strengthens their remediation effects on crude oil-contaminated soil.

To investigate the effects of the mixing of litters on their remediation efficiency in petroleum-contaminated soil, litters from two common plants in the petroleum-contaminated region of Northern Shaanxi, China, Bothriochloa ischaemum (L.) Keng and Sophora davidii Kom. ex Pavol., and their mixture were mixed with 45g/kg petroleum-contaminated soil. Based on these, a 150-day simulated remediation experiment was conducted at 25°C and consistent moisture conditions. The effects on the degradation of petroleum components and the restoration of nutrient contents, pH, and enzymatic activity in the disturbed soil were detected. The effects of the litter treatments on the community structure and carbon source utilization characteristics of soil microorganisms were also studied. The results indicated that all litter treatments significantly accelerated the degradation of petroleum components, while the mixing of litter exhibited significant synergistic effects, leading to significantly higher degradation rates of saturated hydrocarbons, aromatic hydrocarbons, and nonhydrocarbon substances than the observed rates in the single-litter treatments and the predicted rates based on the single-litter treatments. Litter treatment significantly increased the N and P contents and enzymatic activity of contaminated soil. The effects of mixed litter on soil chemical and biological properties fell between the effects of the 2 types of single-litter treatments. However, the mixing of litters exhibited significant synergistic effects in supplementing available P and increasing sucrase, dehydrogenase, lignin peroxidase, and laccase activity, while it exhibited significant antagonistic effects in supplementing nitrate nitrogen and increasing urease, phosphatase, polyphenol oxidase, and manganese peroxidase activity. Litter treatment significantly altered the community structure of soil microorganisms. The relative abundances of some petroleum-degrading microbial phyla or genera in mixed litter-treated soil were significantly different from those in single litter-treated soils, which might contribute to the strengthened remediation effects of mixed litter treatment. The results might provide a theoretical basis for the more effect utilization of biomass resources in the remediation of petroleum-contaminated soil.

The drivers of soil microbial communities structure on forest stands along the altitudinal gradient in western carpathians

This study examines the effect of the soil physicochemical properties and the vegetation diversity and composition on the soil microorganism community structure on the temperate forest stands along the altitudinal gradient. The studied stands were located at three altitudes (600, 900, and 1200 m a.s.l.) on five separate mountain slopes (treated as independent replicates) in the Western Carpathians Mountains (Poland). The soil physicochemical characteristics varied widely between the stands on these same altitude, and only the organic matter content, water-holding capacity and dissolved organic nitrogen differed significantly between the different altitudes, exhibited highest values in the stands at 1200 m a.s.l. The vascular plant species number, including trees, shrubs and understorey decreased with an increase in the altitude. Multivariate analysis (CCA, ANOSIM) indicated that the plant diversity and composition differed significantly between 600 m a.s.l. and 1200 m a.s.l. and was related to altitude, soil pH and fertility, defined as P and K content. Soil microbial biomass and community structure was measured using PLFA (phospholipid fatty acids) analysis. PLFA pattern did not differ between altitudes but was related to the number of plant species, soil pH and C:N ratio. Taking all stands altogether, we showed clear relationship between the plant diversity and composition and the PLFA pattern (Mantel test). Additionally, we indicated that the main factor affecting both the plant diversity and composition as well as microbial community structure was the soil pH.

Elevational is the main factor controlling the soil microbial community structure in alpine tundra of the Changbai Mountain

To reveal the self-coordination mechanism of the fragile ecosystem of alpine tundra, we explored the relationship between soil microorganisms and other elements. On the alpine tundra of the Changbai Mountain, different vegetation types, altitudes and soil properties were selected as driving factors of soil microbial community. Soil microbial community, C- and N-cycling functional microbial and fungal biomass were analyzed. Structural equation model was used to study the control of biotic and abiotic factors in rhizosphere soil microbial community. The results showed that the pH value of soil had the strongest direct impact on the diversity and community structure of soil microorganisms, and had significant correlation with most of the C- and N-cycling functional microbial; organic carbon and vegetation also have strongest direct effect on fungal biomass, but all of them were not main factors influence soil microbial community structure, the elevation was the main controlling factor. In addition, the elevation mainly through indirect action affects the soil microbial community by driving distribution of plant species, soil organic carbon and pH value. This finding highlighted that elevation was the main predictor to determine rhizosphere microbial community structure but not vegetation in alpine tundra of Changbai Mountain.

Effects of long-term fertilization on soil ammonia-oxidizing microorganisms

Long-term fertilization can change the supply of soil carbon and nitrogen (N), with consequences on the abundance and community structure of soil microorganisms. Based on the long-term fertilization positioning experiment station of brown earth, we analyzed the dynamics of soil ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) under different fertilization treatments, including no fertilization (CK), low level of inorganic N fertilizer (N2), high level of inorganic N fertilizer (N4), and organic manure combined with inorganic N fertilizer (M2N2), aiming to provide a basis for microbiological mechanism of soil N transformation and improvement of soil fertility. The results showed that the ratio of AOA to AOB abundance was 2.28-61.95 under different fertilization treatments. Compared with that in CK, the AOA abundance was reduced by 1.6%-13.6% after long-term fertilization. The abundance of AOB in N4 treatment decreased first and then increased with soil depths, but with contrary results in other treatments. The Shannon diversity index (H), evenness index (J), and Simpson index (S) of AOB were higher than those of AOA. The AOB diversity was increased at 0-20 cm soil layer in M2N2 treatment, while that of AOA was decreased. Soil AOB clustered with soil depths, and neither AOA nor AOB community clustered with fertilization treatments. In summary, long-term fertilization altered the composition of AOA and AOB. AOA was sensitive to environment, whereas AOB was more abundant and stable.

Microbial Community Structure and the Distribution of Antibiotic Resistance Genes in Soil Contaminated by Sulfamethoxazole

A pot experiment was carried out to simulate soil contaminated by sulfamethoxazole at different concentrations. The community structure of soil microorganisms was investigated using Illumina high-throughput sequencing, and 64 subtypes of antibiotic resistance genes (ARGs) resistant to six classes of antibiotic were also analyzed by PCR and droplet digital PCR. The results showed that soil contamination with sulfamethoxazole had no significant effect on fungal diversity after 120 days (P>0.05) whereas bacterial diversity was significantly reduced (P<0.05). The microbial community structure of the contaminated soil changed significantly, with the dominant bacterial and fungal genera being significantly different from the control soil. Sulfamethoxazole contamination resulted in an increase in ARG diversity, and the abundance of the sulfonamide resistance gene sul1 increased significantly (P<0.05). However, the abundance of the sulfonamide resistance gene sul2, the quinolone resistance genes floR and cmlA1, and the tetracycline resistance genes tet(34), tetG2, tetG1,tetM, and tetA/P did not show significant changes in the contaminated soil (P>0.05).