Abundance Of Bacterial Communities Research Articles

Effects of Simulated Warming on Bacterial Community Structure in Litters of Chinese Fir Based on Displacement Test

Bacterial communities are vital factors for regulating litter decomposition in forests. With the gradual increase in global climate change, the effects of global warming on the decomposition of forest litter have become a cause for concern. In this study, we used a displacement test to simulate the effects of warming (+2.5, +4.6, and +6.5 °C) on the composition and diversity of bacterial communities in Chinese fir litters based on the natural differences in temperature between the elevation of Wuyi Mountain. Warming significantly increased the abundance and diversity of bacterial communities and altered the functional abundance of bacterial communities. Warming significantly increased the relative abundance of Acidothermus and decreased that of Bacteroidetes and Mucilaginibacter. Structural variations in the bacterial communities were closely related to the chemical properties of the litter. The relative abundance of Planctomycetes exhibited a positive association with nitrogen content and a negative association with cellulose content, whereas phosphorus content was the main driving factor of Acidothermus abundance. Warming increased the complexity of the bacterial community structure, which promoted the decomposition of Chinese fir litter and accelerated nutrient cycling in the Chinese fir plantation ecosystem.

Soil Microbial Community Characteristics and Their Effect on Tea Quality under Different Fertilization Treatments in Two Tea Plantations.

Fertilization is an essential aspect of tea plantation management that supports a sustainable tea production and drastically influences soil microbial communities. However, few research studies have focused on the differences of microbial communities and the variation in tea quality in response to different fertilization treatments. In this work, the soil fertility, tea quality, and soil microbial communities were investigated in two domestic tea plantations following the application of chemical and organic fertilizers. We determined the content of mineral elements in the soil, including nitrogen, phosphorus, and potassium, and found that the supplementation of chemical fertilizer directly increased the content of mineral elements. However, the application of organic fertilizer significantly improved the accumulation of tea polyphenols and reduced the content of caffeine. Furthermore, amplicon sequencing results showed that the different ways of applying fertilizer have limited effect on the alpha diversity of the microbial community in the soil while the beta diversity was remarkably influenced. This work also suggests that the bacterial community structure and abundance were also relatively constant while the fungal community structure and abundance were dramatically influenced; for example, Chaetomiaceae at the family level, Hypocreaceae at the order level, Trichoderma at the genus level, and Fusarium oxysporum at the species level were predominantly enriched in the tea plantation applying organic fertilizer. Moreover, the bacterial and fungal biomarkers were also analyzed and it was found that Proteobacteria and Gammaproteobacteria (bacteria) and Tremellomycetes (fungi) were potentially characterized as biomarkers in the plantation under organic fertilization. These results provide a valuable basis for the application of organic fertilizer to improve the soil of tea plantations in the future.

Effects of soil microbial ecology on ginsenoside accumulation in Panax ginseng across different cultivation years

The quality of ginseng is greatly influenced by ecological factors, especially soil factors. However, there are few reports on the association between the physicochemical properties of ginseng rhizosphere soil, enzyme activity, microbial bacterial community, and ginsenoside content accumulation in ginseng planted at different ages. In order to investigate the relationship between the soil microbial ecology of ginseng and the content of ginsenosides, this study compared the differences in the rhizosphere soil microecological environment and ginsenoside accumulation between ginseng planted for one, two, and three years, using soil without ginseng cultivation as a control. The results showed that monomer saponins Ro, Re, Rf, Rb1, and total ginsenoside content increased significantly (P < 0.05), while monomer saponins Rb2, Rd, Rh2, and Rg3 content decreased significantly in three-year-old ginseng, (P < 0.05). And soil pH, soil bulk weight and soil enzyme activity in ginseng rhizosphere soils altered the abundance and diversity of rhizosphere soil bacterial community. Redundancy analysis and Pearson correlation analysis revealed that soil pH, soil bulk density, soil urease, and protease were the primary factors influencing the bacterial community in the soil around roots of one, two, three years old ginseng. Co-occurrence network visualization analysis indicated that seven bacterial communities, Planctomycetota, Methylomirabilota, Verrucomicrobiota and Acidobacteriota at the phylum level, Vicinamibacterales_unclassified, Vicinamibacteraceae_unclassified and Candidatus_Udaeobacter at the genus level, had a significant effect on the synthesis of ginsenosides. In summary, soil urease, pH, and soil bulk density in agricultural soils can regulate soil physicochemical properties, soil enzymatic activities, and soil bacterial community abundance. These factors are key drivers of the ginseng soil microbial ecology in ginseng cultivation. These studies will provide a scientific basis for subsequent optimization of soil improvement techniques for cultivated ginseng in farmland by improving the soil microbial ecology.

Bacterial community diversity, abundance, and composition of rearing water and red tilapia gills from open river cages and earthen ponds in Central Thailand

Bacterial community diversity, abundance, and composition of rearing water and red tilapia gills from open river cages and earthen ponds in Central Thailand

Study on Plant-blanket to reduce heavy metal migration caused by precipitation and to improve the soil environment of pyritic tailings

The increasing demand for mineral resources due to industrial development has led to significant tailings pollution during the mineral extraction process. In the southwestern region of China, a large amount of pyritic tailings containing pyrite cinder easily leaches heavy metals and other pollutants when exposed to precipitation, resulting in widespread soil contamination. Effective remediation methods are urgently needed to address this issue. This study utilized naturally occurring Plant-blanket formed by the symbiosis of moss and herbaceous plants on pyritic tailings as restoration material. Through leaching experiments and staining tracer techniques, the study investigated the ability of Plant-blanket to reduce the migration of heavy metals from pyrite cinder to soil under the influence of precipitation and its role in improving the soil environment. The results showed that within 12 h, the Plant-blanket could absorb water equivalent to 206.9 % of its own weight and had good water retention ability. It reduced the stained area ratio of soil horizontal and vertical profiles after precipitation leaching by a maximum of 76.08 % and 46.41 %, respectively, and improved the pH, cation exchange capacity (CEC), bulk density, and water content of soil at different depths. In addition, after being covered by Plant-blanket, the migration of Cd and Cu was reduced by a maximum of 44.35 % and 55.77 % respectively, and it increased the diversity and abundance of bacterial communities, promoting the recovery of soil microbial ecological functions. These findings indicate that Plant-blanket can regulate water and improve soil environment, and has certain control ability on the migration of Cd and Cu produced by pyritic tailings. Meanwhile, Plant-blanket plays an important role in improving the soil environment in mining areas and promoting ecosystem restoration, providing valuable reference for further exploration of ecological restoration of tailings.

Effects of denitrification on speciation and redistribution of arsenic in estuarine sediments

Microbially-mediated redox processes involving arsenic (As) and its host minerals significantly contribute to the mobilization of As in estuarine sediments. Despite its significance, the coupling between As dynamics and denitrification processes in these sediments is not well understood. This study employed sequential sediment extractions and simultaneous monitoring of dissolved iron (Fe), nitrogen (N), and sulfur (S) to investigate the impact of nitrate (NO3−) on the speciation and redistribution of As, alongside changes in microbial community composition. Our results indicated that NO3− additions significantly enhance anaerobic arsenite (As(III)) oxidation, facilitating its immobilization by increased adsorption onto sediment matrices in As-contaminated estuarine settings. Furthermore, NO3− promoted the conversion of As bound to troilite (FeS) and pyrite (FeS2) into forms associated with Fe oxides, challenging the previously assumed stability of FeS/FeS2-bound As in such environments. Continuous NO3− additions ensured As and Fe oxidation, thereby preventing their reductive dissolution and stabilizing the process that reduces As mobility. Changes in the abundance of bacterial communities and correlation analyses revealed that uncultured Anaerolineaceae and Thioalkalispira may be the main genus involved in these transformations. This study underscores the critical role of NO3− availability in modulating the biogeochemical cycle of As in estuarine sediments, offering profound insights for enhancing As immobilization techniques and informing environmental management and remediation strategies in As-contaminated coastal regions.

Microbial community diversity during algal inhibition using slow-release microcapsules of tea polyphenols

Harmful algal blooms (HABs) resulting from eutrophication pose a major threat to ecosystems and human health, necessitating effective control measures. Allelochemicals have shown their importance in slowing down algal proliferation due to their proven efficacy and low ecological impacts. In this study, allelopathy tea polyphenols (TPs) and β-cyclodextrin were combined to prepare slow-release algicidal microcapsules, and the diversity of microbial community in the algal inhibition process was analyzed. Results showed that TP slow-release microcapsules had strong algicidal activity. When against Microcystis aeruginosa within 20 d, their constant inhibitory rate was up to 99% compared to the control group. Microbial diversity decreased with an increase in algae density, and the species richness and diversity of algae increased under the stress of TP slow-release microcapsules. The redundancy analysis showed that the environmental factors with impacts on the abundance and diversity of bacterial communities in descending order were dissolved oxygen, pH, and temperature. This study provides a theoretical basis for the application of TP slow-release microcapsules to actual water.

Integron-associated genes are reliable indicators of antibiotic resistance in wastewater despite treatment- and seasonality-driven fluctuations

The present study aims to characterize the bacterial community, resistome and integron abundance of a municipal wastewater treatment plant (WWTP) over the course of 12 months and evaluate the year-long performance of integron-related genes as potential indicators of antibiotic resistance mechanisms in influents and effluents. For that, total DNA was extracted and subjected to 16S rRNA-targeted metabarcoding, high-throughput (HT) qPCR (48 targets) and standard qPCR (5 targets). Targets included integrase genes, antibiotic resistance genes (ARGs) and putative pathogenic groups. A total of 16 physicochemical parameters determined in the wastewater samples were also considered. Results revealed that the WWTP treatment significantly impacted the bacterial community, as well as the content in ARGs and integrase genes. Indeed, there was a relative enrichment from influent to effluent of 13 pathogenic groups (e.g., Legionella and Mycobacterium) and genes conferring resistance to sulphonamides, aminoglycosides and disinfectants. Effluent samples (n=25) also presented seasonal differences, with an increase of the total ARGs’ concentration in summer, and differences between winter and summer on relative abundance of sulphonamide and disinfectant resistance mechanisms. From the eight putative integron-related genes selected, all were positively correlated with the total ARGs’ content in wastewater and the relative abundance of resistance to most of the specific antibiotic classes. The genes intI1, blaGES and qacE∆1 were the most strongly correlated with the total concentration of ARGs. Genes blaGES and blaVIM, were better correlated to resistance to beta-lactams, aminoglycosides and tetracyclines. This study supports the use of integron-related genes as powerful indicators of antibiotic resistance in wastewater, being robust despite the variability caused by wastewater treatment and seasonality.

The impact of Sangju Qingjie Decoction on the pulmonary microbiota in the prevention and treatment of chronic obstructive pulmonary disease.

Exploring the effect of SJQJD on the pulmonary microbiota of chronic obstructive pulmonary disease (COPD) rats through 16S ribosomal RNA (rRNA) sequencing. A COPD rat model was constructed through smoking and lipopolysaccharide (LPS) stimulation, and the efficacy of SJQJD was evaluated by hematoxylin and eosin (H&E) staining and Enzyme-Linked Immunosorbnent Assay (ELISA). The alveolar lavage fluid of rats was subjected to 16S rRNA sequencing. The diversity of lung microbiota composition and community structure was analyzed and differential microbiota were screened. Additionally, machine learning algorithms were used for screening biomarkers of each group of the microbiota. SJQJD could improve lung structure and inflammatory response in COPD rats. 16s rRNA sequencing analysis showed that SJQJD could significantly improve the abundance and diversity of bacterial communities in COPD rats. Through differential analysis and machine learning methods, potential microbial biomarkers were identified as Mycoplasmataceae, Bacillaceae, and Lachnospiraceae. SJQJD could improve tissue morphology and local inflammatory response in COPD rats, and its effect may be related to improve pulmonary microbiota.

Enhancing salt tolerance and crop growth in agricultural systems: the impact of magnetized-ionized water irrigation on soil properties, microbial communities, and cotton growth.

The development of agricultural practices requires an understanding of the improvement of salt tolerance and crop growth in agricultural systems through magnetized-ionized water irrigation. This study examined the impacts of fresh water (F), brackish water (B), magnetized-ionized fresh water (MIF), and magnetized-ionized brackish water (MIB) on soil properties and the growth of cotton seedlings through microbial analysis during the cotton seedling period. The results revealed that magnetized-ionized water irrigation improved soil water retention and promoted salt leaching. In comparison with F irrigation, plant height, leaf area index (LAI), dry matter accumulation (DM), and chlorophyll content (SPAD) levels increased by 3.61%, 4.07%, 5.76%, and 1.33%, respectively, under MIF irrigation. Similarly, when compared with B irrigation, LAI, DM, and SPAD increased by 5.13%, 6.12%, and 3.12% under MIB irrigation. Magnetized-ionized water irrigation also led to a notable rise in the relative abundance of beneficial soil bacterial communities, particularly Pseudomonas and Azoarcus, as well as fungal communities like Trichoderma, while reducing the prevalence of pathogenic fungi, such as Lasionectria, Gibberella, and Alternaria. Notably, this irrigation approach induced alterations in soil properties, and partial least squares path modeling revealed significant links between soil properties and both cotton growth and fungal community structure (with path coefficients of -0.884 and 0.693, respectively). This study elucidated the distinct effects of soil properties and growth indices on cotton yield during the seedling period, providing a crucial scientific foundation for enhancing future agricultural production through the use of magnetized-ionized water irrigation. © 2024 Society of Chemical Industry.

Features of bacterial and fungal communities in the rhizosphere of Gastrodia elata cultivated in greenhouse for early harvest.

Symbiotic microbes are essential for developing and growing Gastrodia elata, an achlorophyllous orchid of high medicinal value. Recently, the cultivation of G. elata in greenhouses has been adopted in Korea to produce mature tubers in a short time. However, no studies have been conducted on the microbial community structure of G. elata cultivated in greenhouse environments. Therefore, we analyzed the temporal features of bacterial and fungal communities in the rhizosphere of G. elata at the juvenile [JT; 2 months after sowing (MAS)], young (YT; 6 MAS), and mature (MT; 11 MAS) tuber stages using culture-dependent and high-throughput sequencing technology. The richness and diversity of the bacterial and fungal communities decreased with tuber growth of G. elata. The symbiotic fungi Mycena sp. and Armillaria sp. as well as tuber extract inhibited the growth of various soil-inhabiting fungal and bacterial strains, indicating that G. elata and its symbiotic fungi play important roles in the selection of rhizosphere microbes. Mortierella rishikesha was the most abundant fungal species in the rhizosphere. We also identified the microorganisms potentially beneficial for G. elata development during greenhouse cultivation. Tubers and symbiotic fungi actively exert selective pressure on rhizosphere microbes, influencing the diversity and abundance of bacterial and fungal communities as G. elata grows. This study is a first report on the temporal microbial community structure of G. elata cultivated in greenhouse. The results on the associated microbiome of G. elata will help understand their beneficial interactions with G. elata and contribute to improvement in cultivation.

Bacterial Community Influences the Effects of Lactobacillus acidophilus on Lipid Metabolism, Immune Response, and Antioxidant Capacity in Dogs.

Lactobacillus acidophilus (L. acidophilus), the most prevalent probiotic, has demonstrated the ability to improve the relative abundance of intestinal microorganisms and boost immunity. However, the underlying mechanisms of these effects remain unclear. This study evaluated body weight, nutrient apparent digestibility, serum indices, and bacterial communities in Chinese rural dogs from a L. acidophilus supplementation group (Lactobacillus acidophilus, n = 6) and a control group (CON, n = 6). The results indicated that L. acidophilus had no significant impact on the body weight and apparent nutrient digestibility of Chinese rural dogs. In comparison with the CON group, L. acidophilus significantly reduced the levels of cholesterol (CHO) and increased the levels of IgA, IFN-α, and T-AOC. Bacterial diversity indices were significantly reduced in the LAC group compared to the CON groups, and MetaStat analysis demonstrated notable distinctions in 14 bacterial genera between the groups. These bacterial genera exhibited correlations with physiological indices such as CHO, IgA, IFN-α, and T-AOC. In conclusion, L. acidophilus can modulate lipid metabolism, immunity, and antioxidant capacity by regulating the relative abundance of specific bacterial communities, which helps dogs to adapt to today's lifestyle.

Effect of soil contamination and additives on fermentative profile, microbial community and iron bioaccessibility of alfalfa silage

BackgroundDuring alfalfa harvesting and preservation, it is important to minimize losses and preserve dry matter and nutrients. Soil contamination of alfalfa forage is a common issue that occurs during the ensiling process. Soil contamination can adversely influence the quality of silage, potentially altering the fermentation process, microbial composition, and iron content.ResultsIn this study, different levels of soil (0, 1.5% or 7.5% contamination on a wet basis; silt loam soil) and two types of additives (LP, Lactobacillus plantarum inoculant alone; MLP, combination addition of molasses and Lactobacillus plantarum) were added to alfalfa and subjected to anaerobic fermentation for 45 days to evaluate the iron content as well as the alpha diversity and relative abundance of bacterial and fungal communities. Soil-contaminated alfalfa contained lower levels of LA (14.2–41.8 g kg−1 DM) and higher levels of AN (50.0–156.4 g kg−1 DM) compared to uncontaminated alfalfa. Soil contamination of alfalfa forage increased the abundance of Clostridia, Actinobacteria, and Alphaproteobacteria in silage. The application of LP or MLP in soil-contaminated silage increased the abundance of Lactobacillus and inhibited the growth of Enterococcus faecium, Pediococcus pentosaceus, unclassified_f_Enterobacteriaceae, and Weissella cibaria. In addition, as the level of soil contamination increased, both the total and bioaccessible iron contents in alfalfa silage increased. The dominant bacteria Lactobacillus plantarum exhibited a positive relationship with LA and bioaccessible iron contents and a negative relationship with pH, AN and BA. The dominant fungi Neocosmospora rubicola showed a positive relationship with total iron, BA, AN and pH.ConclusionsSoil contamination of alfalfa increased the abundance of Clostridia, Actinobacteria, and Alphaproteobacteria and it also increased the total and bioaccessible iron content in silage. The addition of LP and MLP improved the fermentation quality of soil-contaminated silage by increasing LA production and reducing the relative abundance of Enterococcus faecium, Pediococcus pentosaceus, unclassified_f_Enterobacteriaceae, and Weissella cibaria.Graphical

Effects of micro/nano-ozone bubble nutrient solutions on growth promotion and rhizosphere microbial community diversity in soilless cultivated lettuces.

Due to its high efficacy as a wide-spectrum disinfectant and its potential for the degradation of pollutants and pesticides, ozone has broad application prospects in agricultural production. In this study, micro/nano bubble technology was applied to achieve a saturation state of bubble nutrient solution, including micro-nano oxygen (O2 group) and micro-nano ozone (O3 group) bubble nutrient solutions. The effects of these solutions on lettuce physiological indices as well as changes in the microbial community within the rhizosphere substrate were studied. The application of micro/nano (O2 and O3) bubble nutrient solutions to substrate-cultured lettuce plants increased the amount of dissolved oxygen in the nutrient solution, increased the lettuce yield, and elevated the net photosynthetic rate, conductance of H2O and intercellular carbon dioxide concentration of lettuce plants. Diversity analysis of the rhizosphere microbial community revealed that both the abundance and diversity of bacterial and fungal communities in the substrate increased after plant cultivation and decreased following treatment with micro/nanobubble nutrient solutions. RDA results showed that the microbial community in the S group was positively associated with EC, that in the CK and O2 groups exhibited a positive correlation with SC, and that in the O3 group displayed a positive correlation with CAT and POD. Overall, the implementation of micro/nanobubble generation technology in soilless substrates can effectively increase the lettuce growth and yield, and O3 had a more pronounced effect on lettuce yield and quality and the microbial community structure in the substrate than O2. Our study would provide a reference and theoretical basis for developing sustainable and green technology for promoting lettuce production and can be a promising alternative to conventional methods for improving crop yields.

Changes in the Soil Microbial Community Structure and Driving Factors during Post-Fire Recovery of the Larix gmelinii Rupr. Forest in Northern China

Fire is crucial for shaping northern forest ecosystems and can affect soil microbial community structure. However, there are few studies on the long-term effects of forest fire disturbance on soil microbial community diversity. In this study, we employed high-throughput sequencing of 16S rRNA and ITS1 to assess variations in the abundance of bacterial and fungal communities in dominant populations at 1, 6, and 11 years post-fire. Furthermore, a comprehensive analysis was conducted to examine the relationship between soil microenvironmental changes and soil microbial communities after fire disturbances, considering soil physicochemical properties, including bulk density, moisture content, pH, organic carbon, total nitrogen, ammonium nitrogen, nitrate nitrogen, available potassium, and available phosphorus. We found that fire significantly increased soil pH, NO3−-N, AP, and AK contents, in which the content of NO3−-N basically recovered to the pre-fire level at 11 years after fire. The soil SOC and TN contents decreased significantly 1 year after the fire. However, compared to the unfired site, the SOC content essentially recovered 11 years after the fire, while TN content was still significantly higher 11 years after fire. Furthermore, fire changed the diversity and richness of soil microbial communities to some extent. PCoA and NMDS analyses suggested that the bacterial community structures in soil samples from different burned areas with different recovery periods exhibited similarity. However, notable differences were observed in the fungal community structures between the 1-year and 6-year post-fire study sites when compared to the unburned control site. Bacterial communities predominantly comprised Proteobacteria, Actinobacteria, and Acidobacteria, while fungal communities were mainly dominated by Ascomycota and Basidiomycota. RDA confirmed the significant roles of SOC, TN, and NO3−-N in affecting the diversity of soil microbial communities. Therefore, our study not only enhances our understanding of the long-term effects of forest fire disturbances on soil properties and soil microbial community structure, but also provides insights for further utilizing and controlling carbon and nitrogen content to regulate soil microbial activity and accelerate the recovery process of burned areas.

A red seaweed Kappaphycus alvarezii-based biostimulant (AgroGain®) improves the growth of Zea mays and impacts agricultural sustainability by beneficially priming rhizosphere soil microbial community.

The overuse of chemical-based agricultural inputs has led to the degradation of soil with associated adverse effects on soil attributes and microbial population. This scenario leads to poor soil health and is reportedly on the rise globally. Additionally, chemical fertilizers pose serious risks to the ecosystem and human health. In this study, foliar sprays of biostimulant (AgroGain/LBS6) prepared from the cultivated, tropical red seaweed Kappaphycus alvarezii increased the phenotypic growth of Zea mays in terms of greater leaf area, total plant height, and shoot fresh and dry weights. In addition, LBS6 improved the accumulation of chlorophyll a and b, total carotenoids, total soluble sugars, amino acids, flavonoids, and phenolics in the treated plants. LBS6 applications also improved the total bacterial and fungal count in rhizospheric soil. The V3-V4 region of 16S rRNA gene from the soil metagenome was analyzed to study the abundance of bacterial communities which were increased in the rhizosphere of LBS6-treated plants. Treatments were found to enrich beneficial soil bacteria, i.e., Proteobacteria, especially the classes Alphaproteobacteria, Cyanobacteria, Firmicutes, Actinobacteriota, Verrucomicrobiota, Chloroflexi, and Acidobacteriota and several other phyla related to plant growth promotion. A metagenomic study of those soil samples from LBS6-sprayed plants was correlated with functional potential of soil microbiota. Enrichment of metabolisms such as nitrogen, sulfur, phosphorous, plant defense, amino acid, co-factors, and vitamins was observed in soils grown with LBS6-sprayed plants. These results were further confirmed by a significant increase in the activity of soil enzymes such as urease, acid phosphatase, FDAse, dehydrogenase, catalase, and biological index of fertility in the rhizosphere of LBS6-treated corn plant. These findings conclude that the foliar application of LBS6 on Z. mays improves and recruits beneficial microbes and alters soil ecology in a sustainable manner.

Effect of Forest Fires on the Alpha and Beta Diversity of Soil Bacteria in Taiga Forests: Proliferation of Rare Species as Successional Pioneers

Forest fires are among the most influential drivers of changes in forest soil bacterial diversity. Nevertheless, little is known regarding the effects of forest fires on maintaining the complex interactions that preserve forest ecosystem stability. Therefore, this study characterized alterations in soil bacterial community composition and diversity within taiga forests subjected to varying disturbance intensities. Particularly, this study examined the bacterial community within a Larix gmelinii fire-burnt site in Daxinganling, analyzing the changes in bacterial community structure and function across light, moderate, and heavy fire-burnt sites, as well as a control sample site, utilizing Illumina MiSeq technology. Through an assessment of bacterial community diversity and soil physicochemical properties (moisture content (MC), pH, microbial biomass carbon (MBC), organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), and available potassium (AP)), we explored the influence of the soil microenvironment on the soil bacterial community structure at the burnt site under different disturbance intensities. Our findings demonstrated that (1) there was no significant change in the Chao index of soil bacteria in the burnt site under different disturbance intensities, whereas the Shannon index decreased significantly (p &lt; 0.05) and the Simpson index increased significantly (p &lt; 0.05) in the burnt site under light and moderate disturbance. (2) The relative abundance of dominant phyla, such as Proteobacteria, Proteobacteria, and Actinobacteriota, did not change significantly in the fire-burnt site under different disturbance intensities, whereas rare species, such as Acidipila, Occallatibacter, and Acidibacter, experienced a significant increase in relative abundance at the genus level. (3) The results of principal coordinates analysis (PCoA) and canonical correlation analysis (CCA) revealed significant differences in the Beta diversity of soil bacteria in the fire-burnt site under varying interference intensities. The Beta diversity of soil bacteria exhibited significant differences (p = 0.001), with MC, pH, TN, AN, and AK identified as significant influencing factors. (4) FAPROTAX functional prediction analyses were conducted to assess the changes in soil bacteria involved in Cellulolysis, Chemoheterotrophy, and Aerobic_Chemoheterotrophy in the fire-burnt site, with the relative abundance of bacteria involved in Chemoheterotrophy being significantly increased (p &lt; 0.05) under different disturbance intensities. Collectively, our findings demonstrated that different disturbance intensities caused by fires significantly affected the Alpha diversity, Beta diversity, and functional abundance of soil bacterial communities in taiga forests, with MC, pH, TN, AN, and AK being identified as key influencing factors. Additionally, the presence of numerous rare species suggests their role as pioneer communities in the succession of soil bacterial communities.

Soil bacterial community characteristics and its effect on organic carbon under different fertilization treatments.

By implementing small-scale and efficient fertilization techniques, it is possible to enhance the activity of microorganisms, thereby improving soil carbon sequestration and ecological value in agriculture. In this study, field experiments were conducted using various types of fertilizers: organic fertilizer, microbial fungal fertilizer, composite fertilizer, and an unfertilized control (CK). Additionally, different dosages of compound fertilizers were applied, including 0.5 times compound fertilizers, constant compound fertilizers, 1.5 times compound fertilizers and CK. Using advanced technologies such as Illumina MiSeq high-throughput sequencing, PICRUSt2 prediction, Anosim analysis, redundancy analysis, canonical correlation analysis, and correlation matrix, soil organic carbon (SOC) content and components, bacterial diversity, metabolic functions, and interaction mechanisms were examined in different fields. The results showed pronounced effects of various fertilization modes on SOC and the bacterial community, particularly in the topsoil layer (0-20 cm). Organic fertilizer treatments increased the richness and diversity of bacterial communities in the soil. However, conventional doses and excessive application of compound fertilizers reduced the diversity of soil bacterial communities and SOC content. Additionally, different fertilization treatments led to an increase in easily oxidizable organic carbon (EOC) contents. Interestingly, the relationship between SOC components and soil bacteria exhibited inconsistency. EOC was positively correlated with the bacterial diversity index. Additionally, Chloroflexi exhibited a negative correlation with both SOC and its components. The influence of metabolismon primary metabolic functions on the content of SOC components in the soil was more notable. It included seven types of tertiary functional metabolic pathways significantly correlated with SOC components (p < 0.05). These findings enhance the understanding of the relative abundance of bacterial communities, particularly those related to the carbon cycle, by adjusting agricultural fertilization patterns. This adjustment serves as a reference for enhancing carbon sinks and reducing emissions in agricultural soils.

Biotic and Abiotic Regulations of Carbon Fixation into Lacustrine Sediments with Different Nutrient Levels.

Lake sediments play a critical role in organic carbon (OC) conservation. However, the biogeochemical processes of the C cycle in lake ecosystems remain limitedly understood. In this study, Fe fractions and OC fractions, including total OC (TOC) and OC associated with iron oxides (TOCFeO), were measured for sediments from a eutrophic lake in China. The abundance and composition of bacterial communities encoding genes cbbL and cbbM were obtained by using high-throughput sequencing. We found that autochthonous algae with a low C/N ratio together with δ13C values predominantly contributed to the OC burial in sediments rather than terrigenous input. TOCFeO served as an important C sink deposited in the sediments. A significantly positive correlation (r = 0.92, p < 0.001) suggested the remarkable regulation of complexed FeO (Fep) on fixed TOC fractions, and the Fe redox shift triggered the loss of deposited OC. It should be noted that a significant correlation was not found between the absolute abundance of C-associating genera and TOC, as well as TOCFeO, and overlying water. Some rare genera, including Acidovora and Thiobacillus, served as keystone species and had a higher connected degree than the genera with high absolute abundance. These investigations synthetically concluded that the absolute abundance of functional genes did not dominate CO2 fixation into the sediments via photosynthesis catalyzed by the C-associating RuBisCO enzyme. That is, rare genera, together with high-abundance genera, control the C association and fixation in the sediments.

Optimizing Typha biochar with phosphoric acid modification and ferric chloride impregnation for hexavalent chromium remediation in water and soil

Considering the persistent and covert nature of heavy metal soil contamination, the sustainable development of ecological environments and food safety is at significant risk. Our study focuses on remediating soils contaminated with chromium (Cr); we introduce an advanced remediation material, iron oxide phosphoric acid-loaded activated biochar (HFBC), synthesized through pyrolysis. This HFBC displays greater microporosity, fewer impurities, and enhanced efficiency for the remediation process. Our research utilized a comprehensive set of analytical techniques, including Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS), alongside adsorption studies to elucidate the Cr removal mechanism. The effectiveness of HFBC in remediation was influenced by several factors: the pH level, dosage of HFBC, the initial concentration of Cr, and the ambient temperature. Our results indicated an optimal chromium (VI) adsorption capacity of 55.5 mg/g by HFBC at a pH of 6.0 and a temperature of 25 °C, with the process adhering to the pseudo-second-order kinetic model and the Langmuir adsorption isotherm, thus suggesting spontaneity in the uptake method. Moreover, this mechanism encompasses both adsorption and reduction reactions. Using HFBC in pot experiments with cabbage indicated not only an increase in soil pH and cation exchange capacity (CEC), but also a surge in bacterial community abundance. Significant reductions in bioavailable chromium were also recorded. Interestingly, HFBC addition bolstered the growth of cabbage, while concurrently diminishing chromium accumulation within the plant, particularly notable as the HFBC application rate increased. In summation, the HFBC produced in our study has demonstrated convincing efficacy in removing chromium from aqueous solutions and soil. Moreover, the positive agronomic implications of its use, such as enhanced plant growth and reduced heavy metal uptake by plants, indicate its high potential for operational value in the domain of environmental remediation of heavy metals.