Changes In Bacterial Community Composition Research Articles

Effects of humic acid application on bacterial diversity under maize cultivation

AbstractThe fundamental ecosystem processes in soil are regulated by microbial communities, and community diversity is implicated by soil environmental conditions. Humic acid (HA) improves soil quality and fertility, stimulating the microbial environment, but the detailed effects remain poorly understood. We investigated the effects of HA rates on soil bacterial diversity, particularly on species richness and community composition in the rhizosphere of corn (Zea mays). Inorganic fertilizer (T2), HA 0.5% (T3), HA 1.0% (T4), HA 1.5% (T5), and HA 2.0% (T6) were applied in soil. Initial soil (O1) and control after harvesting (T1) were included. A total of 3601 operational taxonomic units were captured from the overall sample, and analysis of 16S ribosomal ribonucleic acid amplicon sequencing data indicated that HA did not notably impact species richness. Intriguingly, HA induced changes in bacterial community composition, along with the relative prevalence of specific taxa. Certain associations between soil chemical properties and abundance distribution have been uncovered. Notably, exchangeable Mg2+, Ca2+, and available phosphorus were strongly related to the relative abundance of bacterial phyla. Furthermore, HA potentially shaped the specific bacterial taxa, as the application of HA at different rates had distinct effects on the member of bacterial abundance of each taxon. These findings enhance our understanding of communities potentially being increased or shifted by HA rate addition in short‐term corn cultivation.

Changes in bacterial community composition in the uterus of Holstein cow with endometritis before and after treatment with oxytetracycline

It is important to study the bacteria that cause endometritis to identify effective therapeutic drugs for dairy cows. In this study, 20% oxytetracycline was used to treat Holstein cows (n = 6) with severe endometritis. Additional 10 Holstein cows (5 for healthy cows, 5 for cows with mild endometritis) were also selected. At the same time, changes in bacterial communities were monitored by high-throughput sequencing. The results show that Escherichia coli, Staphylococcus aureus and other common pathogenic bacteria could be detected by traditional methods in cows both with and without endometritis. However, 16S sequencing results show that changes in the abundance of these bacteria were not significant. Endometritis is often caused by mixed infections in the uterus. Oxytetracycline did not completely remove existing bacteria. However, oxytetracycline could effectively inhibit endometritis and had a significant inhibitory effect on the genera Bacteroides, Trueperella, Peptoniphilus, Parvimonas, Porphyromonas, and Fusobacterium but had no significant inhibitory effect on the bacterial genera Marinospirillum, Erysipelothrix, and Enteractinococcus. During oxytetracycline treatment, the cell motility, endocrine system, exogenous system, glycan biosynthesis and metabolism, lipid metabolism, metabolism of terpenoids, polyketides, cofactors and vitamins, signal transduction, and transport and catabolism pathways were affected.

Biochar drives changes in soil bacterial communities and cotton growth by improving nutrients availability under saline conditions

AbstractApplying biochar to saline soil is a novel strategy for improving soil quality. However, how biochar addition amount affects soil nutrients, bacterial communities, and cotton growth at different stages remains unclear. Three biochar treatments, no biochar (BC0), 1% biochar (BC1, w/w), 3% biochar (BC3), and two cotton varieties, salt‐sensitive (SS) and salt‐tolerant (ST), were used in pot experiments, analyzing biochar effects on saline soil nutrients, bacterial communities, and cotton growth. The study found that biochar increased only organic carbon (SOC), total nitrogen (TN), and available potassium (AK) at the seedling stage. However, at the flowering‐boll stage, biochar also increased nitrate () and available phosphorus (AP) and reduced soil salt content. Biochar did not affect α‐diversity at the seedling stage, but BC3 reduced α‐diversity at the flowering‐boll stage. The principal coordinate analysis revealed changes in the soil bacterial community composition that were closely associated with biochar added. From the redundancy analyses, SOC and AK were the leading environmental factors for soil bacterial community composition changes. SOC, TN, and AK correlated positively with Proteobacteria, which increased their relative abundance through biochar addition and correlated negatively with Bacteroidetes, Chloroflexi, and Acidobacteria, which decreased their relative abundance due to biochar. Furthermore, the random forests analysis showed that SOC, Shannon index, and β‐diversity were significant predictors of cotton biomass. In summary, biochar drives changes in bacterial communities in saline soils by increasing nutrients such as SOC and AK, which affect cotton growth. This study provides data to support the application of biochar on saline soils.

Comparison of eating habits and gut microbiota of preschool children with obesity

Aim: Childhood obesity is a global health concern that affects the daily life of children. It has a complex pathogenesis that involves genetic and nutritional factors among others. Moreover, the dysbiosis of gut microbiota has been recently associated with the development and progression of obesity. Methods: A total of 43 faecal samples were collected from Saudi children; among them, 26 were normal and 17 were obese. Whole genomic DNA was extracted from their faecal samples and sequenced using an Illumina Sequencing platform. Results: The gut microbiota was dominated by Phyla Firmicutes (69.00%) and Bacteroidetes (20.00%), followed by Actinobacteria (8.50%). In children with obesity, the abundance of Firmicutes was decreased, while Bacteroidetes was relatively enriched. Verrucomicrobia and Proteobacteria were not detected in the obese group, but they were found in low abundance in the control group. Phylum Firmicutes was dominated by the families Ruminococcaceae (17.86%) and Lachnospiraceae (41.20%). Less Ruminococcaceae was found in the obese group. Phylum Bacteroidetes was dominated by families Bacteroidaceae (12.98%) and Prevotellaceae (4.10%), which were enriched in the obese group. Genus Blautia (14.29%) was highly abundant, followed by Bacteroides (12.98%), Faecalibacterium (10.08%), Bifidobacterium (7.96%), and Prevotella (5.04%). Ruminococcus_g2 and _g4, Subdoligranulum, Roseburia, Fusicatenibacter, Anaerostipes, and Faecalibacterium were decreased (P > 0.05) in the obese group, while Streptococcus, Agathobacter, Prevotella, Bacteroides, and Bifidobacterium were increased (P > 0.05). Conclusions: In conclusion, a diverse bacterial community was profiled in Saudi preschool children, and changes in bacterial community composition were observed between obese- and normal-weight children.

Gut bacterial communities in Atlantic bottlenose dolphins (Tursiops truncatus) throughout a disease-driven (Morbillivirus) unusual mortality event.

Gut microbiomes are important determinants of animal health. In sentinel marine mammals where animal and ocean health are connected, microbiome impacts can scale to ecosystem-level importance. Mass mortality events affect cetacean populations worldwide, yet little is known about the contributory role of their gut bacterial communities to disease susceptibility and progression. Here, we characterized bacterial communities from fecal samples of common bottlenose dolphins, Tursiops truncatus, across an unusual mortality event (UME) caused by dolphin Morbillivirus (DMV). 16S rRNA gene sequence analysis revealed similar diversity and structure of bacterial communities in individuals stranding before, during, and after the 2013-2015 Mid-Atlantic Bottlenose Dolphin UME and these trends held in a subset of dolphins tested by PCR for DMV infection. Fine-scale shifts related to the UME were not common (10 of 968 bacterial taxa) though potential biomarkers for health monitoring were identified within the complex bacterial communities. Accordingly, acute DMV infection was not associated with a distinct gut bacterial community signature in T. truncatus. However, temporal stratification of DMV-positive dolphins did reveal changes in bacterial community composition between early and late outbreak periods, suggesting that gut community disruptions may be amplified by the indirect effects of accumulating health burdens associated with chronic morbidity.

Temperature-mediated microbial carbon utilization in China's lakes.

Microbes play an important role in aquatic carbon cycling but we have a limited understanding of their functional responses to changes in temperature across large geographic areas. Here, we explored how microbial communities utilized different carbon substrates and the underlying ecological mechanisms along a space-for-time substitution temperature gradient of future climate change. The gradient included 47 lakes from five major lake regions in China spanning a difference of nearly 15°C in mean annual temperatures (MAT). Our results indicated that lakes from warmer regions generally had lower values of variables related to carbon concentrations and greater carbon utilization than those from colder regions. The greater utilization of carbon substrates under higher temperatures could be attributed to changes in bacterial community composition, with a greater abundance of Cyanobacteria and Actinobacteriota and less Proteobacteria in warmer lake regions. We also found that the core species in microbial networks changed with increasing temperature, from Hydrogenophaga and Rhodobacteraceae, which inhibited the utilization of amino acids and carbohydrates, to the CL500-29-marine-group, which promoted the utilization of all almost carbon substrates. Overall, our findings suggest that temperature can mediate aquatic carbon utilization by changing the interactions between bacteria and individual carbon substrates, and the discovery of core species that affect carbon utilization provides insight into potential carbon sequestration within inland water bodies under future climate warming.

PCB decomposition promoted by sugarcane bagasse organic waste

This work aimed to explore the changes in the bacterial community composition of soil contaminated with high concentration of polychlorinated biphenyls (PCBs) treated by biostimulation with sugarcane bagasse. Non-sterilized soil samples were spiked with transformer oil contaminated with PCB 18, 52, 66, 87,101, 110, 153, 180, and 187. The biostimulation experiment was performed by mixing non-sterilized PCB-contaminated soil with sterilized sugarcane bagasse and incubating the mixture 90 d in darkness at 25 ± 1 °C. The results showed that percentage removal of 88 % was similar for all PCB congeners in biostimulated soil, independently of their degree of chlorination, and it was accompanied by a significant change in bacterial community composition. Relative abundance of the bacterial communities at the phylum level in biostimulation treatment showed they were conquered by Proteobacteria and Firmicutes, followed by Acidobacteria and Actinobacteria.Bacteriall diversity increased in the biostimulation system due to the enrichment in genera possessing PCB remediation capacity which demonstrated the boosting potential of sugarcane bagasse in soil with high concentration of PCBs.

Heterogeneity changes of active bacterial community on cigar filler leaves after fermentation based on metagenome.

Microorganisms play an important role in cigar fermentation. To further explore the dynamic changes of bacterial community composition, the changes of surface bacterial diversity of cigar filler leaves were investigated in the present study by high-throughput sequencing technology. It was found that the surface bacterial richness was declined after fermentation, and the dominant microorganisms on the surface of cigar filler leaves evolved from Pseudomonas spp. and Sphingomonas spp. before fermentation to Staphylococcus spp. after fermentation. The chemical composition and sensory quality evaluation of cigar filler leaves were closely related to the changes of surface bacterial community. The changes of the dominant surface bacterial community led to the differences of metabolic functions, among which the metabolic pathways such as the synthesis of secondary metabolites, carbon metabolism, and amino acid biosynthesis were significantly different. The results provide a basis for clarifying the roles of bacteria in fermentation of cigar filler leaves.

The metabolome and bacterial composition of high-moisture Italian ryegrass silage inoculated with lactic acid bacteria during ensiling

BackgroundWith its high nutritional value and productivity, Italian ryegrass as a biomass feedstock constantly supplies rumen degradable nitrogen and digestible fiber to ruminants. However, biofuel production is easily reduced during ensiling due to the high-moisture content of Italian ryegrass, leading to economic losses. Lactic acid bacteria inoculants could improve lignocellulosic degradation and fermentation quality and decrease dry matter loss during the bioprocessing of silage. Therefore, this study analyzed the effects of Lactobacillus buchneri TSy1-3 (HE), Lactobacillus rhamnosus BDy3-10 (HO), and the combination of HE and HO (M) on fermentation quality, bacterial community and metabolome in high-moisture Italian ryegrass silage during ensiling.ResultsThe results showed that the pH value was significantly lower in the HO groups than in the other treatments at the end of ensiling, and the dry matter and acetic acid contents were significantly higher in the HO group than in the other inoculated groups. All inoculants decreased the diversity of the bacterial community and significantly increased the relative abundance of Lactobacillus. Inoculation with HO significantly improved the concentrations of organic acids, dipeptides, ferulic acid, apigenin, and laricitrin. Compared with Lactobacillus buchneri TSy1-3 (HE), HO significantly upregulated the flavonoid compounds in the flavone and flavonol biosynthesis pathway.ConclusionsOverall, these findings suggest that inoculation with HO was beneficial for the development of Italian ryegrass as a biomass feedstock, improving fermentation quality, accelerating changes in bacterial community composition and increasing biofunctional metabolites in high-moisture Italian ryegrass silage.

Nitrogen input on organic amendments alters the pattern of soil–microbe-plant co-dependence

The challenges of nitrogen (N) management in agricultural fields include minimizing N losses while maximizing profitability and soil health. Crop residues can alter N and carbon (C) cycle processes in the soil and modulate the responses of the subsequent crop and soil– microbe-plant interactions. Here, we aim to understand how organic amendments with low and high C/N ratio, combined or not with mineral N may change soil bacterial community and their activity in the soil. Organic amendments with different C/N ratios were combined or not with N fertilization as follows: i) unamended soil (control), ii) grass clover silage (GC; low C/N ratio), and iii) wheat straw (WS; high C/N ratio). The organic amendments modulated the bacterial community assemblage and increased microbial activity. WS amendment had the strongest effects on hot water extractable carbon, microbial biomass N and soil respiration, which were linked with changes in bacterial community composition compared with GC-amended and unamended soil. By contrast, N transformation processes in the soil were more pronounced in GC-amended and unamended soil than in WS-amended soil. These responses were stronger in the presence of mineral N input. WS amendment induced greater N immobilization in the soil, even with mineral N input, impairing crop development. Interestingly, N input in unamended soil altered the co-dependence between the soil and the bacterial community to favor a new co-dependence among the soil, plant and microbial activity. In GC-amended soil, N fertilization shifted the dependence of the crop plant from the bacterial community to soil characteristics. Finally, the combined N input with WS amendment (organic carbon input) placed microbial activity at the center of the interrelationships between the bacterial community, plant, and soil. This emphasizes the crucial importance of microorganisms in the functioning of agroecosystems. To achieve higher yields in crops managed with various organic amendments, it is essential to incorporate mineral N management practices. This becomes particularly crucial when the soil amendments have a high C/N ratio.

Hydrogen peroxide treatment mitigates antibiotic resistance gene and mobile genetic element propagation in mariculture sediment

Mariculture sediments have been exchange and propagation sources of antibiotic resistance genes (ARGs). However, no efficient methods have been generated to remove ARGs from sediments. Here, we explored the impact of hydrogen peroxide (H2O2) and aeration on the efficient removal of ARGs and mobile genetic elements (MGEs) in mariculture sediments. When compared with the aeration group, the ARG abundance was 3.8–32.3% lower in the H2O2 group during the first 14 days. ARG and MGE abundances were also significantly associated with reduced total bacterial population and diversity (P < 0.05). Based on partial squares path modeling, reduction of MGEs had important roles in ARG removal from H2O2 treatments, while in the aeration group, ARG reductions were mainly determined by changes in bacterial community composition. These results suggested that H2O2 treatment represent a promising method for controlling ARG abundance after dosing feed stuff and limit the spread of ARGs in aquaculture environments.

Heterotrophic origin and diverse sources of branched glycerol monoalkyl glycerol tetraethers (brGMGTs) in peats and lignites

The branched glycerol monoalkyl glycerol tetraether lipids of bacteria (brGMGTs, sometimes referred to as H-brGDGTs) are found in marine, lacustrine, and terrestrial mesophilic environments. The abundance of brGMGTs relative to their dialkyl analogues (brGDGTs) has been proposed as a proxy for past continental air and lake water temperature. However, the source(s) of brGMGTs remain unknown. brGDGT production has been described in multiple cultivated Acidobacteria, but so far no brGMGT producer has been identified. We hypothesize that the stable carbon isotopic composition (δ13C) of brGMGTs, as a tracer of carbon source and metabolic pathway, could be used to elucidate the source(s) of brGMGTs relative to brGDGTs. However, the large monoalkyl moiety of these compounds impedes carbon isotopic analysis using conventional techniques based on gas chromatography. Here, we used spooling-wire microcombustion to analyse the stable carbon isotopic composition of brGMGTs and brGDGTs found in peats and lignites. We show that the δ13C of brGMGTs is within ∼2‰ similar to that of brGDGTs from the same samples, as well as the δ13C of the total organic carbon. This suggests that the source organisms use heterotrophic metabolism. However, offsets in the δ13C of brGDGTs and brGMGTs in some samples suggest that not all brGDGT producers also produce brGMGTs. Further, in modern peats we observe downcore increases in brGMGT relative abundance and decreases in the carbon isotopic offsets with brGDGTs, which indicates that brGMGT producers occur throughout the oxic-anoxic continuum and may metabolize different organic carbon pools. Based on this indirect evidence for diverse brGMGT sources, we suggest that in addition to homeostatic responses to temperature, brGMGT relative abundances may be influenced by changes in bacterial community composition in response to additional environmental and biogeochemical parameters.

Sodium hyaluronates applied in the face affects the diversity of skin microbiota in healthy people.

A healthy and stable microbiome has many beneficial effects on the host, while an unbalanced or disordered microbiome can lead to various skin diseases. Hyaluronic acid is widely used in the cosmetics and pharmaceutical industries; however, specific reports on its effect on the skin microflora of healthy people have not been published. This study aimed to determine the effect of sodium hyaluronate on the facial microflora of healthy individuals. Face of 20 healthy female volunteers between 18 and 24 years was smeared with sodium hyaluronate solution once per day. Cotton swabs were used to retrieve samples on days 0, 14, and 28, and high-throughput sequencing of 16 S rRNA was used to determine the changes in bacterial community composition. Facial application of HA can reduce the abundance of pathogenic bacteria, such as Cutibacterium and S.aureus, and increase the colonization of beneficial bacteria. This is the first intuitive report to demonstrate the effect of hyaluronic acid on facial microflora in healthy people. Accordingly, sodium hyaluronate was found to have a positive effect on facial skin health.

The effects of antibiotics and illness on gut microbial composition in the fawn-footed mosaic-tailed rat (Melomys cervinipes).

The gut microbiota are critical for maintaining the health and physiological function of individuals. However, illness and treatment with antibiotics can disrupt bacterial community composition, the consequences of which are largely unknown in wild animals. In this study, we described and quantified the changes in bacterial community composition in response to illness and treatment with antibiotics in a native Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes). We collected faecal samples during an undiagnosed illness outbreak in a captive colony of animals, and again at least one year later, and quantified the microbiome at each time point using 16s ribosomal rRNA gene sequencing. Gut bacterial composition was quantified at different taxonomic levels, up to family. Gut bacterial composition changed between time periods, indicating that illness, treatment with antibiotics, or a combination affects bacterial communities. While some bacterial groups increased in abundance, others decreased, suggesting differential effects and possible co-adapted and synergistic interactions. Our findings provide a greater understanding of the dynamic nature of the gut microbiome of a native Australian rodent species and provides insights into the management and ethical well-being of animals kept under captive conditions.

Bacterial composition along the digestive tract of the Horned Screamer (Anhima cornuta), a tropical herbivorous bird.

The Horned Screamer (Anhima cornuta) is an herbivorous bird that inhabits wetlands of the South American tropical region. We hypothesize that due to its herbivorous niche, its digestive tract compartments may have bacteria specialized in fermenting complex plant carbohydrates. To test this hypothesis, we compared the bacterial communities along the gastrointestinal tract (GIT) of a Horned Screamer captured in Venezuela. Samples were taken from tissues and content of the proventriculus and the small intestine (considered for this study as upper GIT), and the large intestine and cecum (lower GIT). The bacterial community was characterized by sequencing the V4 region of the 16S rRNA gene. Bioinformatic analysis was performed using QIIME, QIITA and Microbiome Analyst. The association between microbial taxonomy and function was analyzed using their Greengenes OTU IDs and a custom KEGG BRITE hierarchical tree and visualized with BURRITO. The Screamer's gastrointestinal microbiota was composed by seven phyla being Firmicutes and Bacteroidetes the most predominant. The dominant taxa in the upper GIT were Helicobacter, Vibrio, Enterobacter, Acinetobacter and Staphylococcus. The dominant taxa in the lower GIT were Oribacterium, Blautia, Roseburia, Ruminococcus, Desulfovibrio, Intestinimonas, Marvinbryantia and Parabacteroides. Complete degradation of cellulose to the end-products acetate, propanoate, butanoate and acetoacetate was found in the upper and lower GIT without significant differences. Our study confirmed changes in bacterial community composition throughout the GIT of the Horned Screamer primarily associated with the production of metabolic end-products of carbohydrate digestion essential for the fermentation of the herbivorous diet.

Establishment of a Standard Tongue Coating Collection Method for Microbiome Studies.

Objective: Recently, researchers have been focusing on characterizing the tongue coating microbiome from patients with digestive tract disease. However, to the best of our knowledge, the tongue coating collection methods have not been standardized until now. This article focuses on bridging this gap by exploring and validating the conditions suitable for the collection of tongue coating samples. Methods: One hundred forty-one healthy subjects were involved in the standardization of the tongue coating collection method. We conducted our standardization experiment by comparing different sampling tools, different preservation solutions, different scraping times, and different storage days with preservation at room temperature. The tongue coating samples from 59 normal individuals were analyzed using 16S ribosomal RNA (rRNA) gene-sequencing technology. The assessment of the quality of extracted DNA was used to verify our established method. We separated the 59 subjects into two groups (aged and younger), and the sequencing results were used to explore the age-related changes in microbiome. Results: Sterile oral swab B is suitable for the collection of tongue coating samples. To obtain a sufficient amount of DNA from a tongue coating sample, we recommend 30 times of tongue coating scraping. Normal saline, phosphate-buffered saline, and commercial preservation solution are all suitable for short-term sample storage (<1 hour). The commercial long-term preservation solution, which stores samples at room temperature (0 hour to 7 days) and can provide for fast commercial transportation, ensures the integrity of the sample DNA as well as the stability of the DNA quality. By using the established method, extracted DNA from all the 59 normal individuals' tongue coating samples passed an appropriate quality bar for microbiome studies. The average value of OD 260/280 is 1.72 ± 0.10; the average total DNA amount is 334.92 ng (±183.81 ng). The bacterial diversity of the tongue coating is increased and the bacterial community composition changes greatly in the NC group (aged normal subjects). Fusobacteriota is found as the dominant bacteria phyla in aged normal subjects with the 16S rRNA gene-sequencing technology. At the genus level, the relative abundance of Fusobacterium, Haemophilus, and Leptotrichia are significantly higher in aged individuals (all p < 0.05), and Neisseria, Streptococcus, and Porphyromonas are significantly higher in younger individuals (all p < 0.05). Conclusion: A participant-friendly tongue coating collection method for microbiome analyses can be established with good reliability and reproducibility. By taking advantage of our established method and 16S rRNA gene sequencing, significant differences were found in diversity and composition of tongue coating microbiota between aged and younger individuals, which contributes to a better understanding of the age-related composition of tongue coating microbiota.

Effects of the Long-Term Continuous Cropping of Yongfeng Yam on the Bacterial Community and Function in the Rhizospheric Soil

Replant disease caused by continuous cropping commonly occurs in yam with consecutive monoculture. However, little is known about how the continuous cropping of yam affects the rhizospheric soil bacterial community structure. In this study, the effects of continuous cropping on rhizospheric soil characteristics, bacterial diversity, and community structure were investigated in the Yongfeng yam fields under monoculture for 1, 5, 10, 15, and 20 years. Long-term monoculture caused soil acidification and increased the concentration of available potassium (AK) and available phosphorus (AP), and soil bacterial richness, but decreased the soil bacterial diversity. An exception was for the field under monoculture for 20 years as it showed the highest bacterial diversity. The relative abundance of beneficial bacteria, such as Proteobacteria, Actinobacteria, and Chloroflexi decreased while the relative abundance of harmful bacteria, including Gemmatimonadetes and Acidobacteria, increased with an extended continuous cultivation time. The networks varied among yams with different cultivation years and became complex with the increase in cultivation years. However, after time in monoculture, the bacterial network decreased gradually and existed stably. These changes in bacterial community composition and co-occurrence of networks may increase the potential risk of soil-borne disease and reduce the yield and quality of Yongfeng yam.

Responses of Free-Living Planktonic Bacterial Communities to Experimental Acidification and Warming

Climate change driven by human activities encompasses the increase in atmospheric CO2 concentration and sea-surface temperature. Little is known regarding the synergistic effects of these phenomena on bacterial communities in oligotrophic marine ecosystems that are expected to be particularly vulnerable. Here, we studied bacterial community composition changes based on 16S rRNA sequencing at two fractions (0.1-0.2 and >0.2 μm) during a 10- day fully factorial mesocosm experiment in the eastern Mediterranean where the pH decreased by ~0.3 units and temperature increased by ~3 °C to project possible future changes in surface waters. The bacterial community experienced significant taxonomic differences driven by the combined effect of time and treatment; a community shift one day after the manipulations was noticed, followed by a similar state between all mesocosms at the third day, and mild shifts later on, which were remarkable mainly under sole acidification. The abundance of Synechococcus increased in response to warming, while the SAR11 clade immediately benefited from the combined acidification and warming. The effect of the acidification itself had a more persistent impact on community composition. This study highlights the importance of studying climate change consequences on ecosystem functioning both separately and simultaneously, considering the ambient environmental parameters.

Temperature fluctuation promotes the thermal adaptation of soil microbial respiration.

The magnitude of the feedback between soil microbial respiration and increased mean temperature may decrease (a process called thermal adaptation) or increase over time, and accurately representing this feedback in models improves predictions of soil carbon loss rates. However, climate change entails changes not only in mean temperature but also in temperature fluctuation, and how this fluctuation regulates the thermal response of microbial respiration has never been systematically evaluated. By analysing subtropical forest soils from a 2,000 km transect across China, we showed that although a positive relationship between soil microbial biomass-specific respiration and temperature was observed under increased constant incubation temperature, an increasing temperature fluctuation had a stronger negative effect. Our results further indicated that changes in bacterial community composition and reduced activities of carbon degradation enzymes promoted the effect of temperature fluctuation. This adaptive response of soil microbial respiration suggests that climate warming may have a lesser exacerbating effect on atmospheric CO2 concentrations than predicted.

尖峰岭热带天然林不同土层细菌群落多样性和组成的海拔变异规律

PDF HTML阅读 XML下载 导出引用 引用提醒 尖峰岭热带天然林不同土层细菌群落多样性和组成的海拔变异规律 DOI: 10.5846/stxb202203090570 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（32171643，U1703332） The altitudinal patterns of bacterial community diversity and composition at different soil depths in Jianfengling mountain tropical forest Author: Affiliation: Fund Project: The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土壤微生物群落结构沿海拔梯度的变异是微生物生物地理学分异和群落空间分布的重要内容，然而，热带森林土壤微生物多样性及其群落特征的海拔模式尚不明确。研究海南省尖峰岭自然保护区0-20cm和20-40cm土壤细菌多样性和群落组成沿海拔梯度（400-1410m）的变化及其与环境因子的关系。结果表明：在0-20cm土壤微生物生物量碳、生物量氮和生物量磷随海拔升高（峰顶降低）而增加，20-40cm土壤微生物生物量碳、生物量氮和生物量磷随海拔升高呈先升高后降低趋势；整体上，变形菌门、放线菌门、酸杆菌门、拟杆菌门、厚壁菌门在0-20cm中占优势，丰度总和占该层细菌总量的88.17%；变形菌门、放线菌门、酸杆菌门、厚壁菌门、绿弯菌门在20-40cm中占优势，丰度总和占该层细菌总量的90.82%；随海拔增加，0-20cm细菌多样性线性减少，20-40cm细菌多样性变化不显著；沿海拔梯度，0-20cm细菌群落组成可分为低（409-1018m），中（1018-1357m）和高（1410m）三个海拔聚集群落，20-40cm细菌群落组成随海拔无显著性变化；两土层细菌多样性与土壤pH显著正相关，土壤细菌群落组成在0-20cm主要受年均温度和pH影响，20-40cm受年均温度和土壤有机碳影响；根据Bray-Curtis指数，0-20cm和20-40cm土壤细菌相似性随地理距离的增加逐渐降低，细菌群落相似性随环境距离的增大也逐渐降低。总之，尖峰岭土壤细菌多样性和群落组成的海拔格局受土壤深度影响，且驱动细菌群落组成变化的因素在土层间不同，暗示在未来气候变化背景下，热带森林0-20cm和20-40cm土壤微生物群落可能具有不同的响应机制。 Abstract:The variation of soil microbial community structure along the altitudinal gradient is an important content of microbial biogeographic differentiation and community spatial distribution. However, the altitudinal pattern of soil microbial diversity and its community characteristics in tropical forests is not clear. This paper studied the changes of bacterial diversity and community composition and their relationship with environmental factors in 0-20cm and 20-40cm soil depths along the altitudinal gradient (400-1410 m) in Jianfengling Nature Reserve, Hainan Province. The results showed that the soil microbial biomass carbon, biomass nitrogen and biomass phosphorus increased with the elevation of 0-20cm (the peak decreased), and the soil microbial biomass carbon, biomass nitrogen and biomass phosphorus increased first and then decreased with the elevation of 20-40cm. On the whole, Proteobacteria, Actinomycetes, Acidobacteria, Bacteroidetes and Firmicutes are dominant in 0-20cm, and the total abundance accounts for 88.17% of the total bacteria in this layer; Proteobacteria, Actinomycetes, Acidobacteria, Firmicutes and Chloroflexi are dominant in 20-40cm, and the total abundance accounts for 90.82% of the total bacteria in this layer. With the increase of altitude, the bacterial diversity decreased linearly in 0-20cm, and that of 20-40cm did not change significantly. The bacterial community composition of 0-20cm can be divided into three communities at low altitude (409-1018 m), medium altitude (1018-1357 m), and high altitude (1410 m) and the bacterial community composition of 20-40cm has no significant change with altitude. There was a significantly positive correlation between bacterial diversity and soil pH in the two soil depths. The composition of soil bacterial community was mainly affected by mean annual temperature and pH at 0-20cm, and by mean annual temperature and soil organic carbon at 20-40cm. According to the Bray Curtis index, the similarity of bacteria in 0-20cm and 20-40cm soil depths decreased with the increase of geographical distance, and the similarity of bacterial community also decreased with the increase of environmental distance. In a word, the altitudinal pattern of soil bacterial diversity and community composition in Jianfengling is affected by soil depth, and the factors driving the change of bacterial community composition are different among soil depths. It is suggested that the soil microbial communities in 0-20cm and 20-40cm of tropical forests may have different response mechanisms under the background of future climate change. 参考文献 相似文献 引证文献