Residual mulch-film characteristics affect heavy metal migration of different soil layers in the subtropical croplands of China.

In recent years, as the abundance of residual mulch film (RMF) in agricultural soil continues to increase, whether the adsorption capacity of its surface affects the migration of heavy metals is a topic of current interest for scholars. Herein, this study investigated the distribution of RMF abundance and metal concentration in different soil layers of 75 plastic-mulching croplands in subtropical China; meanwhile, we also explored the associations of RMF characteristics with metal concentration. The results showed that land type, film mulching amount, and film mulching time were the main factors affecting RMF abundance, distribution, and particle size composition. The highest abundance of RMF was found in the garden soils (910 n·kg-1) with more than 15 years mulching period and more than 19.5 kg hm-2 of annual mulch amount. The lowest abundance of RMF was occurred in the group of field and conservation agricultural land (237 n·kg-1). Moreover, the concentrations of metals in soil, especially Cd, Cr, Cu, and Pb, were closely related to the extent of RMF contamination in the soil environment. In the 0-10 cm and 10-20 cm soil layers, microplastic abundance exhibited a negative correlation with Cr and Cu concentrations and a positive correlation with Pb concentration. Based on the above findings, it is demonstrated that RMF significantly influences the mobility of metals in soil via adsorption processes, with potential synergistic effects between RMF and heavy metals posing a heightened risk to the soil environment.

High-elevation-induced decrease in soil pH weakens ecosystem multifunctionality by influencing soil microbiomes.

Plant environmental stress response has become a global research hotspot, yet there is a lack of clear understanding regarding the mechanisms that maintain microbial diversity and their ecosystem services under environmental stress. In our research, we examined the effects of moderate elevation on the rhizosphere soil characteristics, microbial community composition, and ecosystem multifunctionality (EMF) within agricultural systems. Our findings revealed a notable negative correlation between EMF and elevation, indicating a decline in multifunctionality at higher elevations. Additionally, our analysis across bacterial and protistan communities showed a general decrease in microbial richness with increasing elevation. Using random forest models, pH was identified as the key environmental stressor influencing microbial communities. Furthermore, we found that microbial community diversity is negatively correlated with stability by mediating complexity. Interestingly, while pH was found to affect the complexity within bacterial networks, it did not significantly impact the ecosystem stability along the elevation gradients. Using a Binary-State Speciation and Extinction (BiSSE) model to explore the evolutionary dynamics, we found that Generalists had higher speciation rates and lower extinction rates compared to specialists, resulting in a skewed distribution towards higher net diversification for generalists under increasing environmental stress. Moreover, structural equation modeling (SEM) analysis highlighted a negative correlation between environmental stress and community diversity, but showed a positive correlation between environmental stress and degree of cooperation & competition. These interactions under environmental stress indirectly increased community stability and decreased multifunctionality. Our comprehensive study offers valuable insights into the intricate relationship among environmental factors, microbial communities, and ecosystem functions, especially in the context of varying elevation gradients. These findings contribute significantly to our understanding of how environmental stressors affect microbial diversity and ecosystem services, providing a foundation for future ecological research and management strategies in similar contexts.

Intercropping enhances maize growth and nutrient uptake by driving the link between rhizosphere metabolites and microbiomes.

Intercropping leads to different plant roots directly influencing belowground processes and has gained interest for its promotion of increased crop yields and resource utilization. However, the precise mechanisms through which the interactions between rhizosphere metabolites and the microbiome contribute to plant production remain ambiguous, thus impeding the understanding of the yield-enhancing advantages of intercropping. This study conducted field experiments (initiated in 2013) and pot experiments, coupled with multi-omics analysis, to investigate plant-metabolite-microbiome interactions in the rhizosphere of maize. Field-based data revealed significant differences in metabolite and microbiome profiles between the rhizosphere soils of maize monoculture and intercropping. In particular, intercropping soils exhibited higher microbial diversity and metabolite chemodiversity. The chemodiversity and composition of rhizosphere metabolites were significantly related to the diversity, community composition, and network complexity of soil microbiomes, and this relationship further impacted plant nutrient uptake. Pot-based findings demonstrated that the exogenous application of a metabolic mixture comprising key components enriched by intercropping (soyasapogenol B, 6-hydroxynicotinic acid, lycorine, shikimic acid, and phosphocreatine) significantly enhanced root activity, nutrient content, and biomass of maize in natural soil, but not in sterilized soil. Overall, this study emphasized the significance of rhizosphere metabolite-microbe interactions in enhancing yields in intercropping systems. It can provide new insights into rhizosphere controls within intensive agroecosystems, aiming to enhance crop production and ecosystem services.

Intercropping improves maize yield and nitrogen uptake by regulating nitrogen transformation and functional microbial abundance in rhizosphere soil.

Intercropping-driven changes in nitrogen (N)-acquiring microbial genomes and functional expression regulate soil N availability and plant N uptake. However, present data seem to be limited to a specific community, obscuring the viewpoint of entire N-acquiring microbiomes and functions. Taking maize intercropped with legumes (peanut and soybean) and non-legumes (gingelly and sweet potato) as models, we studied the effects of intercropping on N transformations and N-acquiring microbiomes in rhizosphere soil across four maize growth stages. Meanwhile, we compiled promising strategies such as random forest analysis and structural equation model for the exploitation of the associations between microbe-driven N dynamics and soil-plant N trade-offs and maize productivity. Compared with monoculture, maize intercropping significantly increased the denitrification rate of rhizosphere soils across four maize growth stages, net N mineralization in the elongation and flowering stages, and the nitrification rate in the seedling and mature stages. The abundance of most N-acquiring microbial populations was influenced significantly by intercropping patterns and maize growth stages. Soil available N components (NH4+-N, NO3--N, and dissolved organic N content) showed a highly direct effect on plant N uptake, which mainly mediated by N transformations (denitrification rate) and N-acquiring populations (amoB, nirK3, and hzsB genes). Overall, the adaptation of N-acquiring microbiomes to changing rhizosphere micro-environments caused by intercropping patterns and maize development could promote soil N transformations and dynamics to meet demand of maize for N nutrient. This would offer another unique perspective to manage the benefits of the highly N-effective and production-effective intercropping ecosystems.

Effectiveness of a 10-year continuous reduction of controlled-release nitrogen fertilizer on production, nitrogen loss and utilization of double-cropping rice.

Considerable literature has demonstrated the advantage of controlled-release nitrogen (CRN) fertilizer in improving crop productivity. However, few researches have explored the long-term impacts of using CRN fertilizers as alternative to common urea on production and N utilization in double-cropping paddy. To address this gap, our study utilized a database derived from a 10-year field experiment from 2013 to 2022. During early and late rice seasons, compared to common urea (early rice, 150 kg hm-2; late rice, 180 kg hm-2), CRN fertilizer (150 kg hm-2; 180 kg hm-2) input significantly increased yield by 7.4 %, and 11.7 %, as well as N use efficiency (NUE) from 23.0 % and 24.6 % to 33.0 % and 37.5 %, respectively. CRN application significantly reduced N losses, evidenced by decrease in runoff (23.1 % and 19.4 %), leaching (12.7 % and 12.1 %), ammonia volatilization (28.9 % and 30.2 %), and N2O emissions (10.4 % and 16.1 %). A reduction of 10 % in CRN fertilizer input maintained yield. Compared with normal amount, reducing 10, 20, and 30 % CRN input increased NUE by 7.0-7.6 %, 7.3-7.4 %, and 11.6-12.6 %; reduced runoff loss by 16.1-17.9 %, 27.9-30.7 %, and 35.0-37.2 %; decreased leaching loss by 7.6-12.8 %, 18.1-22.6 %, and 26.5-31.4 %; decreased ammonia volatilization by 9.9-12.3 %, 16.3-22.7 %, and 23.2-29.3 %, and decreased N2O loss by 7.8-13.3 %, 12.8-32.8 %, and 20.3-36.9 %, respectively. Soils with CRN input showed higher total and inorganic N contents than the soils with common urea, and the content increased in parallel with CRN fertilizer input. Soil N content and N runoff loss were significantly related to yield and N uptake, and N runoff and leaching losses were significantly related to NUE. These results support the sustainable use of CRN fertilizers as a viable alternative to common urea, indicating that application rate of 135 and 162 kg N hm-2 of early and late rice, respectively, maintain yield and enhance N utilization in double-season paddy of southern China.

Biodiversity and core microbiota of key-stone ecological clusters regulate compost maturity during cow-dung-driven composting.

The primary objectives of this study were to explore the community-level succession of bacteria, fungi, and protists during cow-dung-driven composting and to elucidate the contribution of the biodiversity and core microbiota of key-stone microbial clusters on compost maturity. Herein, we used high-throughput sequencing, polytrophic ecological networks, and statistical models to visualize our hypothesis. The results showed significant differences in the richness, phylogenetic diversity, and community composition of bacteria, fungi, and eukaryotes at different composting stages. The ASV191 (Sphingobacterium), ASV2243 (Galibacter), ASV206 (Galibacter), and ASV62 (Firmicutes) were the core microbiota of key-stone bacterial clusters relating to compost maturity; And the ASV356 (Chytridiomycota), ASV470 (Basidiomycota), and ASV299 (Ciliophora) were the core microbiota of key-stone eukaryotic clusters relating to compost maturity based on the data of this study. Compared with the fungal taxa, the biodiversity and core microbiota of key-stone bacterial and eukaryotic clusters contributed more to compost maturity and could largely predict the change in the compost maturity. Structural equation modeling revealed that the biodiversity of total microbial communities and the biodiversity and core microbiota of the key-stone microbial clusters in the compost directly and indirectly regulated compost maturity by influencing nutrient availability (e.g., NH4+-N and NO3--N), hemicellulose, humic acid content, and fulvic acid content, respectively. These results contribute to our understanding of the biodiversity and core microbiota of key-stone microbial clusters in compost to improve the performance and efficiency of cow-dung-driven composting.

Biochar amendments combined with organic fertilizer improve maize productivity and mitigate nutrient loss by regulating the C-N-P stoichiometry of soil, microbiome, and enzymes.

Coupled amendments of biochar and organic fertilizers may be one of the effective practice to ensure high cropland productivity and resource use efficiency, but there is little field-based evidence for this. Herein, we employed a eight-years (2014-2021) field experiment to explore the effectiveness of biochar and organic fertilizer amendments on crop productivity and nutrient runoff losses, as well as to further explored their relationships with the carbon:nitrogen:phosphorus (C:N:P) stoichiometry of soil, microbiome, and enzymes. Experiment treatments include No fertilizer (CK), chemical-only fertilizer (CF), CF + biochar (CF + B), 20% chemical N was replaced by organic fertilizer (OF), and OF + biochar (OF + B). Compared with the CF, the CF + B, OF, and OF + B treatments increased average yield by 11.5%, 13.2%, and 32%, average N use efficiency by 37.2%, 58.6%, and 81.4%, average P use efficiency by 44.8%, 55.1%, and 118.6%, average plant N uptake by 19.7%, 35.6%, and 44.3%, as well as average plant P uptake by 18.4%, 23.1%, and 44.3%, respectively (p ≤ 0.05). Compared with the CF, the CF + B, OF, and OF + B decreased average average total N losses by 65.2%, 97.4%, and 241.2%, and average total P losses by 52.9%, 77.1%, and 119.7%, respectively (p ≤ 0.05). Organic-amended treatments (CF + B, OF, and OF + B) significantly changed soil total and available C, N, and P content, soil microbial C, N, and P content, as well as the potential activities of soil C-, N-, and P-acquiring enzymes. Plant P uptake and P-acquiring enzyme activity were the main drivers of maize yield, which was influenced by the contents and stoichiometric ratios of soil available C, N, and P. These findings suggest that organic fertilizer applications combined with biochar have the potential to maintain high crop yields while reducing nutrient losses by regulating the stoichiometric balance of soil available C and nutrients.

The effectiveness of eight-years phosphorus reducing inputs on double cropping paddy: Insights into productivity and soil-plant phosphorus trade-off.

Abundant evidence has demonstrated the feasibility of reducing phosphorus (P) input to face diminishing phosphate rock resources and deteriorating environmental quality in double-cropping paddy. However, the sustainability of reduced P input in the context of maintaining productivity and P efficient utilization is not yet clear. Herein, an 8-year (2013-2021) field-based database was built to explore the effects of reduced P input on rice productivity and the soil-plant P trade-off in double-cropping paddy. In the early and late rice seasons, compared with conventional P fertilization (early rice, 90 kg hm-2; late rice, 60 kg hm-2), the average yield of reduced 10 % P treatment increased by 4.3 % and 2.1 %, respectively; reduced 10-30 % P treatments increased average P use efficiency by 17.1-18.4 % and 14.0-17.2 %, decreased average total P runoff loss by 14.9-33.2 % and 20.8-36.4 %, and decreased average total P leaching loss by 18.5-49.0 % and 24.0-46.1 %, respectively. Compared with conventional fertilization, reduced P fertilizer input by 10 % significantly increased the content of the soil labile-P fraction while reducing that of the soil stable-P fraction. Soil ligand-P and exchangeable-P content decreased with the gradient reduction of P fertilizer input (10-30 %). The main predictors of the change in rice yield and plant P uptake were soil ligand-P and exchangeable-P content, respectively. The dominant predictor of both the P runoff loss and the P activation coefficient was the inorganic P content extracted by NaHCO3. These findings suggest that reduced P input by 10 % could maintain rice productivity and P use efficiency in the double-cropping paddy, and the transformations between soil P components and increases in P bioavailability may be the key drivers maintaining rice productivity and P utilization under the context of reduced P loading.

Dissolved organic matter evolution can reflect the maturity of compost: Insight into common composting technology and material composition.

Dissolved organic matter (DOM) can clearly reflect composting components changes, thus it is supposed to indicate the humification process during composting. To demonstrate this, three compost mixtures and two techniques were arranged. DOM evolution was detected by three spectral techniques. X-ray diffraction (XRD) showed that the crystal structure substances decreased gradually during the composting, including cellulose, struvite, sylvine, quartz, and calcite; Specifically, the struvite was found, which was conducive to the fixation of nitrogen and phosphorus. Fourier transform infrared spectroscopy (FTIR) and three-dimensional fluorescence spectroscopy (3D-EEM) further showed that pig manure-based mixtures, added cabbage, and windrow composting are beneficial to sugar, protein, fulvic acid, and soluble microbial by-products decompose and humic acids produce. This process was closely related to the change of physical-chemical parameters (temperature; pH; moisture content; and NH4+-N content) and maturity index (C/N ratio, E4/E6 and GI). Therefore, DOM evolution could quickly reflect the maturity process of compost. In subsequent research, the quantitative analysis of DOM components can be considered to modify DOM spectral parameters, or to build a model, so as to achieve rapid evaluation of compost maturity.

Community succession of microbial populations related to CNPS biological transformations regulates product maturity during cow-manure-driven composting.

The main objective of present study was to understand the community succession of microbial populations related to carbon-nitrogen-phosphorus-sulfur (CNPS) biogeochemical cycles during cow-manure-driven composting and their correlation with product maturity. The abundance of microbial populations associated with C degradation, nitrification, cellular-P transport, inorganic-P dissolution, and organic-P mineralization decreased gradually with composting but increased at the maturation phase. The abundance of populations related to N-fixation, nitrate-reduction, and ammonification increased during the mesophilic stage and decreased during the thermophilic and maturation stages. The abundance of populations related to C fixation and denitrification increased with composting; however, the latter tended to decrease at the maturation stage. Populations related to organic-P mineralization were the key manipulators regulating compost maturity, followed by those related to denitrification and nitrification; those populations were mediated by inorganic N and available P content. This study highlighted the consequence of microbe-driven P mineralization in improving composting efficiency and product quality.

Synergistically mitigating nitric oxide emission by co-applications of biochar and nitrification inhibitor in a tropical agricultural soil.

Agricultural soils are the hotspots of nitric oxide (NO) emissions, which are related to atmospheric pollution and greenhouse effect. Biochar application has been recommended as an important countermeasure, however, its mitigation efficiency is limited as biochar, under certain conditions, can stimulate soil nitrification. Therefore, biochar co-applied with nitrification inhibitor could optimize the mitigation potential of biochar. Herein, a laboratory-scale experiment was conducted to investigate the effects of co-application of biochar and nitrification inhibitor on NO emission, nitrogen cycling function and bacterial community in a tropical vegetable soil. Results showed that a single application of biochar or nitrification inhibitor significantly decreased NO emissions, and this mitigation effectiveness was amplified by their co-applications. Soil NO2--N intensity, along with abundances of AOB-amoA and nirK were significantly and positively correlated with cumulative NO emissions. The stimulated activity of ammonia monooxygenase and growths of AOB and total comammox Nitrospira by biochar were weakened by nitrification inhibitor, implying decreased nitrification-driven NO production. The nitric oxide reductase activity and related qnorB abundance in nitrification inhibitor-added soils were increased by biochar, indicating promoted NO consumption during denitrification. The nirK abundance and NO2--N intensity were decreased more by co-applications of biochar or nitrification inhibitor. Moreover, both biochar and nitrification inhibitor changed bacterial ß-diversity, and their co-application synergistically enriched Armatimonadetes and Verrucomicrobia abundances and decreased WPS-2 abundance. This study highlights that co-applications of biochar and nitrification inhibitor can make their respective advantages complementary to each other, thereby achieving a larger mitigation of NO emissions from agricultural soils in tropical regions.

The effectiveness of reed-biochar in mitigating phosphorus losses and enhancing microbially-driven phosphorus dynamics in paddy soil.

Biochar is a promising novel material for mitigating phosphorus (P) loss and enhancing P retention in chemical-amended agricultural soils. However, the optimal application rate for aforesaid effectiveness and potential drivers of the process are not well understood. Herein, a column-based pot experiment was carried out to investigate how and to what extent reed-biochar is effective in positively triggering P loss and availability in paddy soils treated by chemical fertilizer. Compared with chemical-only treatment, the accumulated leakage of total P, dissoluble P, and particulate P in chemical fertilizer coupled with 1-4% reed-biochar treatment decreased by 5.3-13.3%, 8.3-10.4%, and 3.0-15.4%, respectively. The accumulated leakage of total P and dissoluble P in 6-8% rate treatments was increased by 5.6-7.5% and 18.3-32.9%, respectively. Increasing reed-biochar rate from 1% to 8% caused an enhancement in soil total P and available P content and P activation coefficient, and the 4% rate achieved a similar effectiveness to the higher rate. Reed-biochar application increased the abundance and diversty of soil phoD-harboring microbes (P < 0.05), while the increment had little to do with the application rate. Soil phoD-harboring community composition and total C content were the main predictors of the P leaching losses, and meanwhile, the total C content was the dominated predictor of soil P retention and availability. These results suggest that adding 1-4% reed-biochar was more beneficial to mitigate paddy P loss and to enhance soil P availability. This study highlights the importance of understanding how microbial populations mediate P transformation to decipher the biochar-driven improvement of soil P utilization.

Understanding how reed-biochar application mitigates nitrogen losses in paddy soil: Insight into microbially-driven nitrogen dynamics.

Biochar application to chemical-amended paddy soils has been proposed as a potential strategy to enhance nitrogen (N) retention and nitrogen use efficiency (NUE) by crops. However, optimal concentrations for these enhancements and the potential drivers are not well understood. Herein, a column-based pot experiment was carried out to investigate the impacts of reed-biochar application rate on N losses and dynamics in paddy soils treated by chemical fertilizer, and particularly, to explore the dominant factors of the processes. The addition of 2-4% reed-biochar had the most significant effects on mitigating N loss by leaching. Reed-biochar amendment increased soil total N and mineral N (NH4+-N and NO3--N) content, and denitrifying gene abundance, and the increments of those variables were positively related to the application rate. Soil treated with 1-4% reed-biochar at harvest period showed higher gene abundances of ammonia-oxidizing and dissimilatory nitrate reduction to ammonium (DNRA) and higher activity of ß-1,4-N-acetyl-glucosaminidase (NAG) and leucine aminopeptidase compared with the 4-8% application rate. The amoA-AOA gene abundance, NAG activity, and total carbon (C) content were the main predictors of total N and mineral N accumulated leakage. Total C content was the main predictor of soil total N and mineral N content, followed by the pH and NAG activity. These results suggest that adding 2-4% reed-biochar was more beneficial to mitigate N loss and thus enhance soil N storage and availability. This study highlights the importance of understanding how microbial populations mediate N transformation to decipher biochar-driven NUE enhancement in paddy soils.

Deciphering the dominant components and functions of bacterial communities for lignocellulose degradation at the composting thermophilic phase.

The decomposition and transformation of organic matters during composting process are performed by various microorganisms. However, the bacterial communities and their functions usually vary with composting materials. Here the dominant bacterial genera and their functions were identified at the thermophilic phase during composting of mulberry branches with silkworm excrement (MSE), pig manure (MPM) and cow manure (MCD). The activities of ß-glucosidase and endoglucanase were highest for MCD (1.31 and 17.15 µg g-1 min-1) and lowest for MPM (0.92 and 14.22 µg g-1 min-1). Random Forest model and correlation analysis revealed that Stenotrophomonas, Bacillus, and Sinibacillus were the dominant bacterial genera involved in lignocellulose degradation regardless of composting materials. Carbohydrate metabolism, amino acid metabolism, and DNA replication and repair were primary functions of the bacterial communities for the three types of composting. The quantification of lignocellulose degradation genes further verified the dominant functions of the bacterial communities.

Deciphering the diversity and functions of plastisphere bacterial communities in plastic-mulching croplands of subtropical China.

Considering the inhomogeneity of plastisphere and surrounding soil, it is plausible that the microbial community colonizing it also varies, affecting soil services and sustainability. Herein, we analyzed the soil and film residue from fifty-five plastic-mulching croplands in the subtropical areas of China. Based on the outcomes of this analysis, we explored the diversity and functions of the associated bacterial communities. Alpha-diversity and phylogenetic diversity of the plastisphere bacterial community was significantly lower than the surrounding soil. The average net relatedness and net nearest taxa indices of samples were less than zero. Four phyla and twenty genera were enriched in the plastisphere compared to the surrounding soil. Ecological networks of the plastisphere community showed multiple nodes, but fewer interactions, and the members of Bradyrhizobium, Rhodospirillaceae, and Bacillus were indicated as the hub species. Predicted pathways related to human disease, as well as the metabolisms of cofactors, vitamins, amino acids, and xenobiotic biodegradation, were reinforced in the plastisphere, and meanwhile, accompanied by an increase in abundance of genes related to carbon, nitrogen, and phosphorus cycles. These results demonstrated the diversity and functions of the plastisphere microbiome and highlighted the necessity for exploring the ecological and health risks of plastic residue in croplands.

Microbial generalist or specialist: Intraspecific variation and dormancy potential matter.

Microbial generalists and specialists coexist in the soil environment while having distinctive impacts on microbial community dynamics. In microbial ecology, the underlying mechanisms as to why a species is a generalist or a specialist remain ambiguous. Herein, we collected soils across a national scale and identified bacterial generalists and specialists according to niche breadth at the species level (OTU level), and the single-nucleotide differences in each species were measured to investigate intraspecific variation (at zero-radius OTU level). Compared with that of the specialists, the intraspecific variation of the generalists was much higher, which ensured their wider niche breadth and lower variability. The higher asynchrony and different niche preferences of conspecific individuals and the higher dormancy potential within the generalists further contributed to their stability in varying environments. Besides, generalists were less controlled by environmental filtering, which was indicated by the stronger signature of stochastic processes in their assembly, and had higher diversification and transition rates that allowed them to adapt to environmental changes to a greater extent than specialists. Overall, this study provides a new comprehensive understanding of the rules of assembly and the evolutionary roles of bacterial generalists and specialists. It also highlights the importance of intraspecific variation and the dormancy potential in the stability of species.

Forest conversion to plantations: A meta-analysis of consequences for soil and microbial properties and functions.

Primary or secondary forests around the world are increasingly being converted into plantations. Soil microorganisms are critical for all biogeochemical processes in ecosystems, but the effects of forest conversion on microbial communities and their functioning remain unclear. Here, we conducted a meta-analysis to quantify the impacts that converting forests to plantations has on soil microbial communities and functioning as well as on the associated plant and soil properties. We collected 524 paired observations from 138 studies globally. We found that conversion leads to broad range of adverse impacts on soils and microorganisms, including on soil organic carbon (-24%), total nitrogen (-29%), bacterial and fungal biomass (-36% and -42%, respectively), microbial biomass carbon (MBC, -31%) and nitrogen (-33%), and fungi to bacteria ratio (F:B, -16%). In addition, we found impacts on the ratio of MBC to soil organic C (qMBC, -20%), microbial respiration (-18%), N mineralization (-18%), and enzyme activities including ß-1,4-glucosidase (-54%), ß-1,4-N-acetylglucosaminidase (-39%), and acid phosphatase (ACP; -34%). In contrast, conversion to plantations increases bacterial richness (+21%) and microbial metabolic quotient (qCO2 , +21%). The effects of forest conversion were consistent across stand ages, stand types, and climate zone. Soil C and N contents as well as the C:N ratio were the main factors responsible for the changes of microbial C, F:B, and bacterial richness. The responses of qCO2 , N mineralization, and ACP activity were mainly driven by the reductions in F:B, MBC, and soil C:N. Applying macro-ecology theory on ecosystem disturbance in soil microbial ecology, we show that microbial groups shifted from K to r strategists after conversion to plantations. Our meta-analysis underlines the adverse effects of natural forests conversion to plantations on soil microbial communities and functioning, and suggests that the preservation of soil functions should be a consideration in forest management practices.

Community-level dormancy potential regulates bacterial beta-diversity succession during the co-composting of manure and crop residues.

This study aimed to disclose the bacterial diversity succession during the co-composting of manure and crop residues and to provide new insight into the role of community-level dormancy potential in diversity succession. Illumina sequencing and PICRUSt-estimated metagenomes were used for this purpose. The bacterial richness and phylogenetic diversity decreased in the early and middle stages of composting and were maintained to a stable status in the late stage. Both composting phases and raw materials impacted the aforementioned alpha diversity significantly, while the composting phases had a greater (80%-94%) impact than the raw materials (1%-18%). Bacterial beta-diversity succession exhibited selectivity as the composting proceeded, and the dominant taxa changed into salt- and heat-resistant genera such as Bacillus, Glycomyces, and Halocella. Meanwhile, Georgenia, Actinomadura, and Ruminofilibacter were identified as the dominant predictor taxa of bacterial community succession in composting. Roughly, the abundance of genes underlying dormancy strategies, including sporulation factors (spo0A gene), toxin-antitoxin systems (dinJ/yafP, mazF/E, hipA/O, and relA/E genes), and resuscitation-promoting factors (rpfC gene), increased as composting proceeded and reached the highest in the thermophilic or maturation phases. Co-occurring relationships between bacterial communities and genes underlying dormancy strategies in different composting phases comprised multiple associations dominated by positive edges (50%-97%). The stability in genes underlying dormancy strategies and aggregate dormancy potential had a positive linear correlation with that in bacterial beta diversity (R2 = 0.26-0.42; P < 0.05), but not related significantly to that in richness and phylogenetic diversity. This study highlighted the importance of understanding how community-level dormancy strategies mediated microbial succession in composting to better predict compost maturity and product quality.

Fungal community succession contributes to product maturity during the co-composting of chicken manure and crop residues.

The succession of the fungal community during the co-composting of chicken manure and crop residues and its role in relation to compost maturity was deciphered using Illumina sequencing and FUNGuild (Fungi + Functional + Guild) tool. In the maturation phase of composting, the relative abundance of pathogenic and symbiotrophic fungi decreased by 68%-85% and 145%-622%, respectively, as compared to the initial phase, which showed 574%-720% increase in the saprotrophic guild. The pathogenic and saprotrophic fungi abundance was correlated to compost maturity represented by germination index and humic spectroscopic ratio (p < 0.05). Random forest analysis and structural equation modeling elucidated the positive effects of the aforementioned fungal taxa on compost maturity, and these effects were mediated by the micro-environmental variables, such as temperature, NH4+-N/NO3--N ratio and total organic carbon content. Our study outlines the importance of fungal community succession for improving composting performance and efficiency.

Paeoniflorin Sensitizes Breast Cancer Cells to Tamoxifen by Downregulating microRNA-15b via the FOXO1/CCND1/ß-Catenin Axis.

BACKGROUND: Paeoniflorin (Pae) possesses anti-tumor activity in various malignancies. However, it is unclear whether Pae plays a sensitizer role in breast cancer (BC) and the molecular mechanisms involved in this process. Our oligonucleotide microarray revealed that microRNA (miR)-15b is the most significantly downregulated miRNA in MCF-7/4-hydroxytamoxifen (4-OHT) cells treated with Pae. This paper summarized the relevance of Pae in BC cell endocrine resistance to tamoxifen (Tam) and the molecular mechanisms involved miR-15b expression. MATERIALS AND METHODS: 4-OHT-resistant BC cell lines were developed and treated with different concentrations of Pae. Flow cytometry, lactose dehydrogenase activity, caspase-3 activity, colony formation, and EdU assays were carried out to assess the impact of Pae on BC cells. Differentially expressed miRNAs in BC cells treated with Pae were analyzed by microarray. Targeting mRNAs of screened miR-15b as well as the binding of forkhead box O1 (FOXO1) to the cyclin D1 (CCND1) promoter sequence were predicted through bioinformatics analysis. Finally, the expression of ß-catenin signaling-related genes in cells was detected by Western blotting. RESULTS: Pae (100 µg/mL) inhibited the clonality and viability of BC cells, while enhancing apoptosis in vitro. Pae also repressed miR-15b expression. Overexpression of miR-15b restored the growth and resistance of BC cells to 4-OHT. Moreover, Pae promoted FOXO1 expression by downregulating miR-15b, thereby transcriptionally inhibiting CCND1 and subsequently blocking ß-catenin signaling. CONCLUSION: Pae inhibits 4-OHT resistance in BC cells by regulating the miR-15b/FOXO1/CCND1/ß-catenin pathway.