Response Of Soil Bacterial Communities Research Articles

Response of bacterial communities in desert grassland soil profiles to acid mine drainage pollution

Acid mine drainage (AMD) causes serious environmental pollution, which imposes stresses on soil ecosystems. Therefore, it is critical to study the responses of soil bacterial communities to AMD pollution in ecologically fragile desert grasslands. Here, the bacterial community composition, structure, and assembly processes in vertical soil profiles of an AMD contaminated desert grassland were explored using 16S rRNA high-throughput sequencing. The results showed that the surface layers of the profiles exhibited lower pH and higher heavy metals (HMs) content due to AMD influence. The AMD contamination led to reduced bacterial diversity in the surface soil layer of the profiles and significantly changed the bacterial community composition and structure. Gradients in pH, TK, TN, and HMs were the main factors driving bacterial community variability. In contrast to the uncontaminated profile, deterministic processes were important in shaping soil bacterial community in the AMD contaminated profiles. These findings will enhance understanding about the responses of soil bacteria in desert grassland soil to the environmental changes caused by AMD contamination and will improve the remediation of AMD contaminated soil.

Effects of Increasing the Nitrogen–Phosphorus Ratio on the Structure and Function of the Soil Microbial Community in the Yellow River Delta

Nitrogen (N) deposition from human activities leads to an imbalance in the N and phosphorus (P) ratios of natural ecosystems, which has a series of negative impacts on ecosystems. In this study, we used 16s rRNA sequencing technology to investigate the effect of the N-P supply ratio on the bulk soil (BS) and rhizosphere soil (RS) bacterial community of halophytes in coastal wetlands through manipulated field experiments. The response of soil bacterial communities to changing N and P ratios was influenced by plants. The N:P ratio increased the α-diversity of the RS bacterial community and changed the structure of the BS bacterial community. P addition may increase the threshold, causing decreased α-diversity of the bacterial community. The co-occurrence network of the RS community is more complex, but it is more fragile than that of BS. The co-occurrence network in BS has more modules and fewer network hubs. The increased N:P ratio can increase chemoheterotrophy and denitrification processes in the RS bacterial community, while the N:P ratio can decrease the N-fixing processes and increase the nitration processes. The response of the BS and the RS bacterial community to the N:P ratio differed, as influenced by soil organic carbon (SOC) content in terms of diversity, community composition, mutualistic networks, and functional composition. This study demonstrates that the effect of the N:P ratio on soil bacterial community is different for plant roots and emphasizes the role of plant roots in shaping soil bacterial community during environmental change.

Different responses of soil bacterial community to plant-plant interactions under organic-inorganic fertilizers affect seedling establishment during subalpine forest succession.

Rhizosphere bacterial community as a valuable indicator of soil quality and function, has been widespread studied. However, little knowledge is about the response of bacterial communities to plant-plant interaction and different fertilizers during secondary forest succession. We conducted a field pot experiment applying organic and inorganic fertilizers to monocultures and mixed cultures of dominant plant species from mid- to late-successional stages (Salix oritrepha, Betula albosinensis, and Picea asperata), and investigated the responses of plant growth and rhizosphere bacterial communities. Results indicated that growth rate of plant height varied among plant species, but no significant differences were observed in soil bacterial diversity and composition among plant species or inter-specific interactions under control. Compared to control, inorganic fertilizer resulted in increases in plant growth and the relative abundance of Proteobacteria, Patescibacteria, Bacteroidetes and Gemmatimonadetes, while simultaneously leading to decrease in the relative abundance of Acidobacteria, Actinobacteria, Chloroflexi, Rokubacteria and Planctomycetes. When grown with other species, the bacterial communities in the mixture resembled those of S. oritrepha in singular monoculture under inorganic fertilizer treatment, but plant growth was not affected by interspecific interaction. Unlike inorganic fertilizer, organic fertilizer significantly affected bacterial communities and increased bacterial diversity, but did not alter the effects of plant-plant interactions on bacterial communities. It was also observed that organic fertilizer facilitated later successional species' growth (P. asperata and B. albosinensis) by the mid-successional species (S. oritrepha), ultimately facilitating secondary forest succession. In addition, plants at different successional stages harbor specific bacterial communities to affect their growth, and the bacterial communities contributed more than soil properties to the variations in the plant growth of S. oritrepha and P. asperata though the bacterial communities were regulated by soil factors. This finding highlights the significance of the rhizosphere bacteria on plant growth and plant community succession. It also emphasize the importance of considering both plant-plant interactions and diverse fertilizer types in forest restoration efforts and provide valuable insights into optimizing agronomic practices for secondary forest succession.

Depth-dependent responses of soil bacterial communities to salinity in an arid region

Soil salinization adversely affects soil fertility and plant growth in arid region worldwide. However, as the drivers of nutrient cycling, the response of microbial communities to soil salinization is poorly understood. This study characterized bacterial communities in different soil layers along a natural salinity gradient in the Karayulgun River Basin, located northwest of the Taklimakan desert in China, using the 16S rRNA Miseq-sequencing technique. The results revealed a significant filtering effect of salinity on the bacterial community in the topsoil. Only the α-diversity (Shannon index) in the topsoil (0–10 cm) significantly decreased with increasing salinity levels, and community dissimilarity in the topsoil was enhanced with increasing salinity, while there was no significant relationship in the subsoil. BugBase predictions revealed that aerobic, facultatively anaerobic, gram-positive, and stress-tolerant bacterial phenotypes in the topsoil was negatively related to salinity. The average degree and number of modules of the bacterial co-occurrence network in the topsoil were lower under higher salinity levels, which contrasted with the trends in the subsoil, suggesting an unstable bacterial network in the topsoil caused by higher salinity. The average path length among bacterial species increased in both soil layers under high salinity conditions. Plant diversity and available nitrogen were the main drivers affecting community composition in the topsoil, while available potassium largely shaped community composition in the subsoil. This study provides solid evidence that bacterial communities adapt to salinity through the adjustment of microbial composition based on soil depth. This information will contribute to the sustainable management of drylands and improved predictions and responses to changes in ecosystems caused by climate change.

Response of Soil Bacterial Communities and Potato Productivity to Fertilizer Application in Farmlands in the Agropastoral Zone of Northern China

The characteristics and responses of soil bacterial communities and potato productivity to different fertilization treatments in farmlands in the agropastoral zone of Inner Mongolia were investigated. Moreover, the diversity and structure of soil bacterial communities and potato productivity under different fertilization treatments (no fertilization, CK; phosphorus-deficient treatment, NK; conventional fertilization, NPK; and organic–inorganic combination, NPKM) were assessed using Illumina high-throughput sequencing. The results revealed that soil pH, organic matter (SOM), total nitrogen (TN), and total phosphorus (TP) content, and potato productivity were significantly increased under fertilizer treatments (NK, NPK, and NPKM) compared with those under CK, with NPKM treatment having the best enhancement effect. The application of organic fertilizers significantly increased the Shannon, evenness, Chao1, and Ace indices of soil bacterial communities and reshaped the bacterial community structure. Random forest model analysis revealed that soil pH and TP significantly affected soil bacterial diversity, whereas soil pH, SOM, TP, and TN significantly affected soil bacterial community structure. Correlation and structural equation modeling analyses revealed that soil TP and SOM indirectly affected potato productivity by changing soil bacterial diversity and community composition. The results of this study provide a scientific basis for improving the quality and productivity of farmland soil to guide the rational fertilization of farmlands in the agropastoral zone of northern China.

Response of the soil bacterial community to seasonal variations and land reclamation in a desert grassland

Soil bacteria are important participants in biogeochemical cycles, and the stability of their community structure is not only affected by fluctuations in time and environment, but also by the participation and regulation of anthropogenic interference. With the increasing reclamation of farmland in the agropastoral transitional zone of northern China, it is imperative to understand the characteristics of soil bacterial communities in response to seasonal variations and anthropogenic reclamation. In this study, desert grassland, artificial shrubland, and desert grassland reclaimed farmland on the western side of the Mu Us Sandy Land were used as research objects. The following main results were obtained through soil sampling in April and September, and physicochemical analyses combined with 16S high-throughput sequencing: seasonal variations increased soil pH and soil water content, whereas land reclamation significantly increased soil total carbon, total phosphorus, soil available phosphorus, and soil available potassium contents. Changes in soil physicochemical properties altered the structure of soil bacterial communities to varying degrees, with Actinobacteriota and Acidobacteriota being the differential phyla among the three sampling sites under seasonal variations (p < 0.05). The relative abundance of Actinobacteriota was significantly higher in April than in September at all three sampling sites, and that of Acidobacteriota was significantly lower in April than in September. Therefore, Actinobacteriota and Acidobacteriota are key ecological indicators for predicting changes in the physicochemical properties of desert grassland soils. Actinobacteriota not only affected the complexity of the soil bacterial network, but also had a significant linear relationship with bacterial community stability. Actinobacteriota subgroups (Solirubrobacterales, Propionibacterales, 0319-7L14, and Gaiellales) were also strongly associated with soil bacterial community stability. Solirubrobacter, Gaiella, Nocardioides, Marmoricola, and Kribbella, which play crucial roles in maintaining the stability of bacterial communities, responded positively to changes in pH and soil water content. This study demonstrates the response of soil bacterial communities to environmental changes in a desert grassland and emphasizes the importance of Actinobacteriota as an indicator of soil ecosystem health.

Competitive relationships due to similar nutrient preferences reshape soil bacterial metacommunities

Paddy soil, as an ecosystem with alternating drained and flooded conditions, microorganisms in it can maintain the stability of the ecosystem by regulating the composition and diversity of its species when disturbed by external biotic or abiotic factors, and the regulatory mechanism in this process is a controversial topic in ecological research. In this study, we investigate the effects of pigeon feces addition on bacterial communities in three textured soils, two conditions (drained and flooded) based on microcosm experiment using high-throughput sequencing techniques. Our results show that pigeon feces addition reduced environmental heterogeneity and community diversity, both under flooded and drained conditions and in all textured soils, thereby decreasing the effectiveness of environmental selection and increasing diffusion limitations among bacterial communities. Bacterial communities are altered by environmental factors including total organic carbon, available nitrogen, total phosphorus, available phosphorus and available potassium, resulting in the formation of new community structures and dominant genera. Bacteria from pigeon feces did not colonize the original soil in large numbers, and the soil bacterial community structure changed, with some species replaced the indigenous ones as new dominant genera. As nutrient diffusion increases the nutrient content of the soil, this does not lead to species extinction; however, nutrient diffusion creates new nutrient preferences of the bacterial community, which causes direct competition between species, and contributes to the extinction and immigration species. Our results suggest that species replacement is an adaptive strategy of soil bacterial community in response to dispersal of pigeon feces, and that bacterial community regulate diversity and abundance of the community by enhancing species extinction and immigration, thereby preventing bacteria in pigeon feces from colonizing paddy soils and maintaining ecosystem stability.

Effects of soil conditioners on vineyard saline soil physicochemical properties and bacterial community in arid areas

AbstractSoil salinization adversely affects soil quality and ecosystem. Many researches have tried to ameliorate saline soils by soil conditioners. However, little is known about the differences in the responses of soil bacterial communities to natural and artificial conditioners applied to saline soils. Therefore, in this study, the effects of natural humic acid (IK), synthetic polymer (IP), and composite material (IF) (mixture of IK and IP (1:1)) on bacterial community structure and functional genes in saline soil were evaluated to clarify their differences. The results showed that the application of the three soil conditioners significantly reduced soil pH and Na+ content but increased soil alkaline phosphatase, urease, invertase and catalase activities, bacterial diversity, and nutrients, compared to the control (no conditioner). IK application increased bacterial relative abundance (e.g., Subgroup_6, RB41, MND1, and KD4‐96) and metabolic functions (e.g., Two‐component system and Biosynthesis of amino acids) by increasing soil nitrogen and maintaining K+ and Na+ balance. IP application increased soil alkaline phosphatase and urease activities as well as bacterial relative abundance (e.g., Subgroup_6, RB41, MND1, Gemmatimonadaceae, and KD4‐96) and metabolic functions (e.g., Quorum sensing and carbon metabolism) by increasing soil organic carbon/nitrogen content. IF application increased the bacterial relative abundance of Subgroup_6, RB41, and MND1 by increasing soil available nitrogen and regulated their metabolic pathways (e.g., ABC transporters and microbial metabolism). On the whole, IK, IP, and IF could regulate the structure and function of soil bacterial community in saline soils. This study clarifies difference in the effects of different soil conditioners on the amelioration of saline soils from the perspective of soil microbiology, and provides a reference for the amelioration of saline soils in arid areas.

Evaluation of Soil Total Nitrogen as an Indicator of Soil Bacterial Community Response to Biochar and Plant Growth-Promoting Rhizobacteria Applications

Biochar and plant growth-promoting rhizobacteria (PGPR) are widely used as an amendment for soil physicochemical properties and soil bacterial community diversity. In Guangxi, China, we carried out a study to determine how PGPR and biochar influence the soil’s environmental stability in an Eucalypt plantation. We applied biochar and PGPR in a contrasting application manner to an acidic red loam soil. Thus, three treatments were set up as 5 × 1010 CFU·mL−1 PGPR-only (MB0), 20 t·hm−2 biochar-only (B20), and co-application of 20 t·hm−2 biochar and 5 × 1010 CFU·mL−1 PGPR (MB20), as well as no biochar and no PGPR (M0B0). Our results indicated that MB20 significantly decreased the soil total nitrogen (TN) and increased the soil total phosphorus (Soil TP), soil ammonium nitrogen (NH4+), and soil water content (SWC) when compared with the control. The MB20 also significantly increased the Simpson, ACE, and Chao indices of the soil bacterial community’s diversity relative to the control. We also observed a significant effect of the Soil TN on both the bacterial community and the functional diversity in soil. These findings may indicate that assessing the soil N status is expected to be an essential indicator of the soil microenvironment’s response to biochar and PGPR applications.

Responses of soil bacterial communities and maize yields to sulfur application across four soil types.

This study assessed the effects of S application on maize yields and soil bacterial communities across four sites with different soil types and three S application rates (0 kg ha-1, 30 kg ha-1, and 90 kg ha-1). Changes in soil properties, bacterial community diversity, structure, and their contributions to maize production were evaluated post-S application treatments. (1) S application decreased soil pH, increased available sulfur (AS), and boosted maize yields in all soil types. (2) Reduced Chao1 and Shannon diversity indices were observed in black soil after S application. (3) Bacterial community structure was significantly affected by S application, except in sandy soil, impacting key stone taxa abundance. (4) Black soil showed higher sensitivity to S application due to less stable bacterial community structure. (5) Soil physicochemical indicators altered by S application, such as AS and pH, mediated bacterial diversity, influencing maize yield. Organic matter (OM) had the most significant direct positive effect on yield, followed by AS and bacterial community diversity. This study emphasizes the impact of S application on soil properties and bacterial communities in diverse soil types. Understanding these mechanisms can guide precision S application practices for maize yield regulation.

Effect of soil flooding and drying on the metabolic pathways of CO2 fixing microorganisms along an elevation gradient in the Three Gorges Reservoir drawdown area

AbstractThe construction of dams and subsequent water level fluctuations significantly alters the environmental conditions of reservoir ecosystems, affecting the metabolic pathways of CO2 fixing microorganisms (CFMs) and carbon storage in drawdown areas. We investigated the response of soil bacterial communities and carbon fixation pathways to periodic flooding and drying at different elevations by collecting surface soil samples (0–10 cm) in the drawdown area of the Three Gorges Reservoir. The results show that periodic flooding and drying increased the complexity of bacterial co‐occurrence networks. We identified the reductive citrate cycle (rTCA cycle), dicarboxylate‐hydroxybutyrate cycle (DC/4‐HB cycle), 3‐Hydroxypropionate cycle (3‐HP cycle) and reductive pentose phosphate cycle (Calvin cycle) as the main carbon fixation pathways. Notably, as the inundation duration increased, the abundance of the Calvin cycle and its key gene (cbbL) gradually decreased. We also found that soil moisture, pH and the different organic carbon components affected the composition of bacterial communities and the abundance of carbon fixation pathways. These findings elucidate evolutionary trends bacterial communities and the impacts of water level fluctuations on microbial‐mediated carbon cycling processes because of dam construction.

The Response of Soil Bacterial Communities to Cropping Systems in Saline–Alkaline Soil in the Songnen Plain

The high salt content in saline–alkaline land leads to insufficient nutrients, thereby reducing agricultural productivity. This has sparked widespread interest in improving saline–alkaline soil. In this investigation, 16S rRNA gene high-throughput sequencing was employed to examine the impacts of three cropping systems (monoculture, rotation, and mixture) on soil bacterial communities. It was found that cropping rotations and mixtures significantly increased soil bacterial α-diversity. Random forest analysis showed a significant linear relationship between AK and EC and bacterial α-diversity. In addition, principal coordinates analysis (PCoA) further confirmed the significant differences in β-diversity between different soil layers. Through co-occurrence network analysis, it was found that cropping rotations and mixtures increased the stability and complexity of co-occurrence networks. By calculating NST to analyze the assembly process of soil bacterial communities in different cropping systems, it was found that the assembly process of soil bacterial communities was dominated by a stochastic process. Functional prediction results showed that a large number of C, N, and S cycling microbes appeared in soil bacterial communities. Our study aims to establish a fresh perspective on the improvement and recovery of saline–alkaline soil.

Reforestation regulated soil bacterial community structure along vertical profiles in the Loess Plateau

IntroductionReforestation is a widely used strategy for ecological restoration in areas facing ecological degradation. Soil bacteria regulate many functional processes in terrestrial ecosystems; however, how they respond to reforestation processes in surface and deep soils remains unclear.MethodsArtificial Robinia pseudoacacia plantation with different stand ages (8, 22, and 32 years) in a typical fallow forest on the Loess Plateau was selected to explore the differential response of soil bacterial community to reforestation in different soil depths (surface 0–200 cm, middle 200–500 cm, and deep 500-100 cm). Soil bacterial diversity, community composition and the co-occurrence patterns, as well as the functions were analyzed.Results and discussionThe results showed that alpha diversity and the presence of biomarkers (keynote species) decreased with the increasing soil depth, with a sharp reduction in family-level biomarker numbers in 500–1,000 cm depth, while reforestation had a positive impact on bacterial alpha diversity and biomarkers. Reforestation induced a more loosely connected bacterial community, as evidenced by an increase of 9.38, 22.87, and 37.26% in the average path length of the co-occurrence network in all three soil layers, compared to farmland. In addition, reforestation reduced the hierarchy and complexity but increased the modularity of the co-occurrence network in top and deep soil layers. Reforestation also led to enrichment in the relative abundance of functional pathways in all soil layers. This study sheds light on the strategies employed by deep soil bacteria in response to reforestation and underscores the significant potential of deep soil bacteria in terrestrial ecosystems, particularly in the context of human-induced environmental changes.

Responses of Soil Bacterial Communities and Chemical Properties to Grazing Regulation in Desert Steppe

Due to the region’s social economy and historical culture, rough grazing has led to unresolved grassland-based ecological problems in Northern China. Soil microorganisms are essential structural and functional components of underground ecosystems, and the effects of various grazing intensities on the physicochemical properties and bacterial communities of soil are unclear. A stocking density regulation experiment was carried out in the desert steppe of the Inner Mongolia Autonomous Region. In the study area, four grazing intensities were set, namely, the enclosure control group (CK), light grazing, moderate grazing, and heavy grazing. Field investigations and 16S rRNA sequencing were used to compare and analyze the characteristics of soil bacterial community structures and their correlations with soil nutrient factors under different grazing intensities. The experiment showed the following results: (1) The Shannon, Simpson, and Pielou indices of the light grazing group were significantly higher than those of the CK (p &lt; 0.05), and the indices of the moderate and heavy grazing groups were lower than those of the CK, but the difference was not significant, and there were no significant differences in the Chao1 index between each group. (2) Acidobacteria, Actinobacteria, Proteobacteria, and Chloroflexi were the main bacterial phyla. (3) With the exception of soil organic matter and available potassium, which had significant negative correlations with the Shannon index (p &lt; 0.05), other soil factors had no significant correlation with the soil bacterial diversity. (4) The contents of soil organic matter, total phosphorus, alkali-hydrolyzed nitrogen, available phosphorus, and available potassium influenced the differences between soil bacterial communities under different grazing intensities.

Ecological Responses of Soil Bacterial Communities to Heavy Metal Contamination Surrounding a Typical Coal-based Industrial Region

Microbial communities in the soil might be affected by heavy metal contamination caused by anthropogenic activities associated with the coal-based industry. This study analyzed the differences in soil physicochemical properties, heavy metal concentrations, and enzyme activities surrounding different coal-based industrial fields(coal mining industry, coal preparation industry, coal-based chemical industry, and coal-fired power industry) in Shanxi Province, North China. Moreover, soil samples from farmland and parks away from all the industrial plants were collected as references. Based on the 16S rRNA high-throughput sequencing, we identified the composition of soil bacterial communities. Spearman correlation and redundancy analyses were used to explore the relationships between soil bacterial communities and environmental factors. The results showed that the concentrations of most heavy metals were greater than the local background values, particularly for As, Pb, and Cd, but they did not exceed the risk screening values of Soil Environment Quality:Risk Control Standard for Soil Contamination of Agriculture Land(GB 15618-2018). There were significant differences in soil cellulase and alkaline phosphatase activities among sampling fields. Actinobacteria was the predominant bacterial phyla, with the highest relative abundance surrounding the coal-based chemical plants, followed by Proteobacteria. The soil bacterial communities were significantly affected by Cd, total carbon, total nitrogen, and alkaline phosphatase activity. This study could provide a foundation for the ecological remediation of the coal-based industrial region in the future.

Subtle Responses of Soil Bacterial Communities to Corn-Soybean-Wheat Rotation

Crop rotational diversity can improve crop productivity and soil health, and boost soil microbial diversity. This research hypothesized that a 3-year rotation of corn-soybean-wheat (CSW), compared with a 2-year corn-soybean (CS) rotation, would result in a more diverse and more complex soil bacterial community, together with a greater abundance of beneficial bacteria. This was evaluated in a replicated experiment established in 2013 at two locations in Ohio (United States). The soil bacterial communities under soybean were compared between CS and CSW at both studied sites in 2018 and 2019, through 16S ribosomal DNA amplicon metabarcoding. Experimental site was the main driver of bacterial richness and evenness. Significant effects on bacterial community composition were observed in response to the interaction between site, rotational sequence, and year of study. Eight bacterial amplicon sequence variants were identified within all CSW treatments and were not present in CS. Several taxa were differentially abundant between rotation treatments, including the genera Ralstonia being more abundant in CS. Co-occurrence networks, including hub taxa, were generally different between rotation treatments and year, with more structure observed in CSW networks for one of the studied sites. Few bacterial genera were consistently identified as hubs across all networks, including an unidentified member of order Acidobacteriales, while other hubs were unique for CSW networks, including members of the family Gemmatimonadaceae. Finally, the composition of the bacterial communities at the northwestern site positively correlated with plant biomass and active carbon, whereas more recalcitrant pools (total carbon and organic water) correlated with the bacterial communities at the western site.

Elevational characteristics of soil bacterial community and their responses to soil translocation at a mountainside in northwest Sichuan, China

How the soil bacterial communities vary with elevation is context-dependent, and the effect of soil translocation between elevations on bacterial community structure and metabolic function was not fully understood yet. Here, the bacterial community composition and diversity at five elevations along a 1600–3000 m elevation gradient on a mountainside in northwest Sichuan were characterized, and the responses of soil bacterial community to simulated climate changes were further studied by soil translocation reciprocally at three elevations for 12 months. Significant differences were found in soil temperature and moisture at different elevations, but there was no observed change in bacterial alpha diversity. The relative abundance of bacterial phyla was significantly different among the five elevations except for Proteobacteria (the dominant bacterial phyla in five elevation), and most bacterial phyla correlated with soil temperature, moisture, pH and soil bulk density. The direct effect of soil properties (pH, soil nutrients and soil bulk density) on soil bacterial community was stronger than the direct effect of temperature and moisture. Soil translocation changed the relative abundance of some bacterial phyla, and taxonomic groups with significant changes were mainly non-dominant phyla rather than the dominant phyla. Metabolism was the primary function of bacterial community at all elevations, which accounted for ~ 80% of relative abundance, and soil translocation had little effect on metabolic function. These findings indicated that soil bacterial dominant taxa and soil bacterial metabolic functions are relatively stable, which contribute to the stability of the ecosystem when response to the climate change in the future.

Assessing soil bacterial community response to organophosphate pesticides in agricultural field of Yogyakarta, Java, Indonesia

Soil contamination by pesticides is one of the world’s most pressing environmental issues. The widespread use of Organophosphate pesticides (OPPs) in agriculture has led to biological diversity changes. The indigenous bacterial community played significant roles in the remediation of soil contaminated with OPPs. This study examines the overall bacterial community composition of three agricultural fields in Yogyakarta, Java, Indonesia, that were exposed to OPPs. The agricultural field was divided into zones near the beach, residential, and mountainous. Sequencing 16S rRNA amplicon fragments used to analyze the soil bacterial community. It was discovered that Proteobacteria, Actinobacteria, and Firmicutes comprised the majority of the bacterial community. In addition, the samples contain a high relative abundance of Bacillus, Bradyrhizobium, Chryseobacterium, Cystobacter, Microvirga, and Burkholderia. The high alpha diversity indexes suggest that the agricultural soil microbiome provides important ecological services and may harbor a wide variety of bacteria and genes with biotechnological applications. The physicochemical soil characteristics are also correlated with the bacterial community structure. The findings can be used to develop bioremediation strategies that employ native microbes to clean and restore agricultural soil contaminated with OPPs.

Phosphorus Coupled with High Nitrogen Addition Exerts a Great Influence on Soil Bacterial Community in a Semiarid Grassland.

Nitrogen (N) and phosphorus (P) addition, either individually or in combination, has been demonstrated to enhance plant productivity in grassland ecosystems. Soil bacterial community, which is the driver of litter decomposition and nutrient cycling, is assumed to control responses of terrestrial ecosystem structure and function to N and P addition. Using a high-throughput Illumina MiSeq sequencing platform, we conducted a 9-year field experiment of N (0, 5, 10, and 20 g N m-2 yr-1) and P (0 and 10 g P m-2 yr-1) additions in the Inner Mongolian steppes to elucidate long-term effects of N and P addition on soil bacterial richness, diversity and composition. We found that N addition reduced the relative abundance of Acidobacteria, Chloroflexi, and Nitrospirae, while increased that of Bacteroides. The results showed that the bacterial biomarker was enriched in P addition treatments, either individually or combined with N addition. Both N and P addition altered the bacterial community structure, while only N addition greatly decreased bacterial richness and diversity. More importantly, we showed that all of these effects were most significant in N3P treatment (20 g N m-2 yr-1 and 10 g P m-2 yr-1), implying that P coupled with a high-level N addition exerted a great influence on soil bacterial community. Structural equation models revealed that N and P addition had a great direct effect on soil bacterial community and an indirect effect on it mainly by changing the litter biomass. Our findings highlighted that severe niche differentiation was induced by P along with a high-level N, further emphasizing the importance of simultaneously evaluating response of soil bacterial community to N and P addition, especially in the context of increasing anthropogenic nutrient additions.

Fertilizer management methods affect bacterial community structure and diversity in the maize rhizosphere soil of a coal mine reclamation area

BackgroundThe filling or mixed stack mode is a frequently used coal mine reclamation engineering technique that results in changes in soil microbial community structure and nutrient content, which lead to considerable deviations from the characteristics of restored coal mine reclamation areas that can be used for farming. Fertilization is an effective strategy for improving soil fertility in such areas; however, the response of soil bacterial communities, especially in the crop rhizosphere soil, to different fertilization techniques in such soils remains unclear. Therefore, we investigated the effects of different fertilization management methods, including no fertilizer, farmers' practice, inorganic fertilizer, organic fertilizer, and organic–inorganic fertilizer, on maize yield, rhizosphere soil bacterial community and diversity, soil physicochemical properties, and nitrogen cycle-related gene abundance (nifH, AOB, and nirS).ResultsThe results showed that organic–inorganic fertilizer treatment significantly improved maize yield. The relative abundance of the dominant phyla did not significantly differ between the treatment groups. However, the Chao 1 and Shannon indices of the bacterial community significantly changed between the no fertilizer and organic–inorganic fertilizer treatments. Notably, organic–inorganic fertilizer application significantly increased the copy numbers of nifH and nirS. Further, moisture, bulk density, and available phosphorus content were identified as the major driving factors responsible for the changes in bacterial community structure, diversity, and copy numbers of nifH, nirS, and AOB.ConclusionsThe results of this study revealed that organic–inorganic fertilizer application improved soil bacterial diversity and the copy numbers of nifH and nirS in maize rhizosphere soil. Therefore, we concluded that organic–inorganic fertilizer is an effective strategy for the restoration of maize rhizosphere soil properties and bacterial communities in coal mine reclamation areas.