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In this study, soil samples from the typical rice-wheat cropping system in Jiangsu Province, China, subjected to different fertilizer application treatments-no carbon (CK), urea (UR), straw (SR), pig manure (PM), starch (ST), and glucose (GL)-were used to determine potential anaerobic ammonium oxidation (anammox) rate and its association with bacterial abundance, diversity, and activity by using DNA stable isotope probing combined with N isotope tracing and molecular techniques. The effects of different organic carbon sources on anammox were significant, in the following order: GL > ST, SR > UR > PM; anammox activity differed significantly across treatments; however, the C active anammox bacteria were only closely related to Ca. Brocadia. The anammox hydrazine synthase β subunit functional gene sequences were highly associated with the Candidatus genus Brocadia in PM and CK treatments. The different organic carbon sources had different inhibitory effects with anammox rate, which dropped from 3.19 to 1.04 nmol dinitrogen gas g dry soil h among treatments. About 4.2-22.3% of dinitrogen gas emissions were attributed to anammox and indicated that a specific population of anammox bacteria was present and varied with the addition of exogenous organic compounds in paddy soils, although a small part of dinitrogen gas was emitted from the soil via anammox. [ABSTRACT FROM AUTHOR]

The anaerobic ammonium oxidation (anammox) process is globally an important nitrogen-cycling process mediated by specialized microbes. However, still little information is documented about anammox microbial community structure under agricultural soils. The anaerobic incubation experiment was conducted to study the impacts of different land use soils fertilized by C-urea on the activity and diversity of anammox bacteria using stable isotope to probe the phospholipid fatty acid (PLFA-SIP). The C was preferentially incorporated in ratios PLFAs 16:1 ω7 c, 16:1 ω5 c, and 16:0. The results revealed that the abundance of the anammox bacteria (both hzs-β and hzo) were observed in vegetable soil V1 and paddy soils (R1 and R2) means that they were positively correlated with C-urea but were negatively correlated with NO -N and NH -N concentrations. Thus, C-PLFAs 16:1 ω7 c, 16:1 ω5 c, and 16:0 could be the biomarker as soil anammox. The anaerobic microbial community composition of soils under different land use systems was diverse, and V1, R1, and R2 had similar microbial diversity and higher microbial biomass. The principal component analysis between soil properties and gene abundance suggested that not only pH but also soil organic matter, available P, and available K were important factors for the anammox process. This study suggested that C-Urea-PLFA for anaerobic incubation was a simple method to study anammox microbial community structure through affecting the soil nutrients, and the different land use systems played important roles in determining the microbial composition of soils. [ABSTRACT FROM AUTHOR]

Cd contamination, especially in farmland soil, can pose serious threats to human health as well as ecological security. Stabilization is an important strategy for agricultural soil Cd remediation. In this study, a Cd-resistant strain (Cupriavidus B-7) was isolated and loaded onto cow manure (CDB), rice straw (RSB) and pine wood biochar (PB) to investigate its effects on Cd stabilization by a 60-day pot experiment. Results indicated that the Cupriavidus B-7-loaded biochar (labelled as CDBB, PBB and RSBB) reduced the CaCl2-extractable Cd by 43.06–59.78%, which was significantly superior to individual applications of Cupriavidus B-7 and biochar. Likewise, the soil physicochemical properties, urease, catalase and phosphatase activities were improved, indicating improved soil health. Consequently, dry weights of pakchoi's shoot and root were increased by 938.9–1230.9% and 149.1–281.2%, respectively, by applying CDBB, PBB and RSBB. Meanwhile, the Cd accumulation in pakchoi shoots decreased by 38.06–50.75%. Notably, the RSBB exhibited an optimal performance on pakchoi growth promotion and Cd accumulation alleviation. The structural equation model indicated the synergistic effect on pakchoi growth promotion and Cd accumulation decreased between biochar and Cupriavidus B-7. Our research provides some new insights into the development of strategies for green and sustainable remediation of Cd-contaminated soil. Highlights: A Cd resistant Cupriavidus B-7 (B-7) was isolated from copper mining soil Biochar, B-7 and their conbination were used to remediate Cd polluted soil Biochar loaded B-7 outperformed individual treatments for Cd stabilization Biochar loaded B-7 alleivated the Cd uptake and promoted pakchoi growth [ABSTRACT FROM AUTHOR]

Aims: Paddy soil is one of the main sources of global nitrous oxide (N2O) emissions via multiple pathways regulated by different microbes. However, the relative contributions of N2O production pathways with the addition of organic carbon (C) in different paddy soils are poorly understood. Methods: 15N-stable isotope and acetylene (C2H2) inhibition were used to differentiate the relative contributions of autotrophic and heterotrophic nitrification (ANF and HNF) and denitrification (DNF) to N2O emissions in two paddy soils (acid vs. neutral soil) with glucose addition. Results: HNF and DNF were the main N2O pathways which contributed between 85% to 100% of the total N2O production at 70% water filled pore space. Low soil pH inhibited soil nitrification and the activity of ammonia oxidizers compared with neutral paddy soil. Glucose reduced nitrification rate and stimulated N2O production significantly, mainly via DNF in the two paddy soils. Moreover, glucose increased the relative contribution of DNF to total N2O production in the first 7 days and total N2O amounts from HNF over the 14-day incubation. Conclusions: HNF and DNF rather than ANF dominated the N2O emissions regardless of soil pH. Glucose had a positive effect on N2O emissions by influencing HNF and DNF. [ABSTRACT FROM AUTHOR]

Background and aims: Different grazing management practices have a significant impact on the sustainability of grassland ecosystems. This study invested the vertical distribution of soil nitrogen (N) forms and soil microbial community structures in a semiarid grassland ecosystem under different grazing management practices in Inner Mongolia. Methods: Soil samples were collected from three semiarid grassland plots subjected to different long-term management practices namely, free grazing (FG) and two different periods of enclosure (E83, enclosed since 1983 and E97, enclosed since 1997). The soil organic nitrogen (N) pools were analyzed by classical methods, and the bacterial community was assessed by PCR-DGGE and high-throughput sequencing. Results: The surface soil N-supplying capacity was in the order of E97 ≥ E83 ≥ FG. The soil ammonium N, amino N, and N-supplying capacity were greater in the enclosed plots than in the FG plot. Additionally, the 0–40-cm soil layer showed the influence of different management practices on the soil properties. The structure and diversity of the soil microbial community also varied with the management type. The soil organic N composition was significantly related to the soil bacterial community structure and microbial categories. Conclusions: An appropriate number of years of fencing helps to improve the soil surface nutrient status, whereas overgrazing and prolonged enclosure are not conducive to the restoration of soil nutrients. Different grazing management practices can affect the microbial community structure and turnover of soil N in grasslands. [ABSTRACT FROM AUTHOR]

To investigate the effects of stocking rates on nitrification activity and active nitrifying communities in a typical steppe grazing system, we conducted a laboratory incubation study using soil from a 10-year-old grassland gradient grazing experiment with sheep. A combination of molecular methods, such as DNA-based stable-isotope probing (DNA-SIP), real-time quantitative PCR, and high-throughput sequencing, was used to identify changes of nitrification activity and active nitrifying communities under different stocking rates (0 (SR0), 3 (SR3), 6 (SR6), and 9 (SR9) sheep per ha). The nitrification activity of soils was significantly increased by light grazing (SR3), while it was significantly decreased by heavy grazing (SR9). Nitrososphaera viennensis lineage of ammonia-oxidizing archaea (AOA) functionally predominated over ammonia-oxidizing bacteria (AOB) in nitrification in the SR3 soil, while the Nitrosospira cluster 3 of AOB was the major player in the SR9 soil. Therefore, stocking rates altered the distribution of active nitrifying communities by affecting soil chemical and physical conditions. [ABSTRACT FROM AUTHOR]

Aims: Potato starch wastewater contains higher contents of essential nutrients, which can be fertilizer to help crop growth. However, the effects of fermented potato fertilizer on soil ecology and microbial community structure have not yet been elucidated. This study aimed to investigate the shifts of active ammonia oxidation microbial communities under different fertilization in a typical soil in North China. Methods: The different levels of fermented potato fertilizer without or with chemical fertilizer were designed by field experiment. Results: The results showed that applying fermented potato fertilizer could significantly increase crop yields by 165–399% compared to Control. The content of available soil nutrients and the activity of saccharase and cellulase were increased when fermented potato fertilizer was applied, and the combination fertilizers further increased the content of Olsen-P by 145.6–166.7%, NO3− by 15.2–81.1%, Total C by 13.8–14%, and Total N by 27.2–34.7% compared with fermented potato fertilizer (PW) treatments. In addition the fermented potato fertilizer significantly stimulated the diversity of soil microbial community and increased the differentiation and stability of soil microbial networks in deep soils. Finally, the change of niche of soil Comammox (COM), ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (AOB) were found after PW treatments. It showed a significant positive correlation between AOA and COM (r = 0.79, P < 0.01), AOB and NOB (r = 0.7, P < 0.05) instead of theoretically the competitive relationship between AOA and COM. Conclusions: One of the reasons crop yield increase is that fermented potato fertilizer can modulate soil nitrification strategy bychanging the niche of soil functional microorganisms to increase fast-acting nutrients and increase crop yield. [ABSTRACT FROM AUTHOR]

China launched Tianwen-1 spacecraft successfully on July 23rd, 2020. The Mars Orbiter Subsurface Investigation Radar (MOSIR) is a subsurface radar sounder as a scientific instrument onboard Tianwen-1 orbiter. It is designed to study the compositions of Martian surface material, subsurface structure, and the ionosphere's total electron content. It can also perform passive observations in a transfer orbit to Mars. The subsurface stratigraphic structure is critical to the study on Mars geological and climatic evolution history. Considering the optimal tradeoff between penetrating depth and range resolution, MOSIR operates at low-frequency and high-frequency channels, with the frequency bands of 10–15 MHz or 15–20 MHz and 30–50 MHz, respectively. MOSIR provides a penetration depth of more than 100 m with a vertical resolution of 7.5 m (20 MHz bandwidth) and 30 m (5 MHz bandwidth) in free space. The range and azimuth focusing techniques are applied in ground data processing to achieve the resolution of several hundred meters (along-track) and several thousand meters (cross-track). MOSIR is intended to search for water ice and liquid water that may be associated with signs of life in the polar layered deposits, Tianwen-1 landing site, and other selected areas. [ABSTRACT FROM AUTHOR]

The effect of grazing on the abundance, composition, and methane (CH4) uptake of methanotrophs in grasslands has been well documented in the past few decades, but the dominant communities of active methanotrophs responsible for CH4 oxidation activity in grazed soils are still poorly understood. In this study, we characterized the metabolically active, aerobic methanotrophs in grasslands with three different levels of grazing (light, medium, and heavy) by combining DNA-stable isotope probing (SIP) and quantitative PCR (qPCR) for methane monooxygenase (pmoA) gene– and 16S rRNA gene–based amplicon sequencing. The CH4 oxidation potential was as low as 0.51 μmol g dry weight−1 day−1 in the ungrazed control, while it decreased as grazing intensity increased in grazed fields, ranging from 2.25 μmol g dry weight−1 day−1 in light grazed fields to 1.59 in heavily grazed fields. Increased CH4 oxidation activity was paralleled by twofold increases in abundance of pmoA genes and relative abundance of methanotroph-affiliated 16S rRNA genes in the total microbial community in grazed soils. SIP and sequencing revealed that the genera Methylobacter and Methylosarcina (type I; Gammaproteobacteria) and Methylocystis (type II; Alphaproteobacteria) were active methanotrophs responsible for CH4 oxidation in grazed soils. Light and intermediate grazing stimulated the growth and activity of methanotrophs, while heavy grazing decreased the abundance and diversity of the active methanotrophs in the typical steppe. Redundancy and correlation analysis further indicated that the variation of bulk density and soil C and N induced by grazing determined the abundance, diversity of active methanotrophs, and methane oxidation activity in the long-term grazed grassland soil. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the responses of nitrifiers and denitrifiers to understand microbial pathways of nitrous oxide (N2O) emissions in grassland soils that received inputs of sheep excreta. Sheep dung and synthetic sheep urine were applied at three different rates, simulating a single, double, or triple overlapping of urine or dung depositions in the field. Quantitative PCR and high-throughput sequencing were combined with process-based modeling to understand effects of sheep excreta on microbial populations and on pathways for N2O production. Results showed that emissions of N2O from urine were significantly higher than from dung, ranging from 0.12 to 0.78 kg N2O-N ha−1 during the 3 months. The N2O emissions were significantly related to the bacterial amoA (r = 0.373, P < 0.001) and nirK (r = 0.614, P < 0.001) gene abundances. It was autotrophic nitrification that dominated N2O production in the low urine-N rate soils, whereas it was denitrification (including nitrifier denitrification and heterotrophic denitrification) that dominated N2O production in the high urine-N rate soils. Nitrifier denitrification was responsible for most of the N2O emissions in the dung-treated soils. This study suggests that nitrifier denitrification is indeed an important pathway for N2O emissions in these low fertility and dry grazed grassland ecosystems. [ABSTRACT FROM AUTHOR]

Little is known about the effects of temperature and drying-rewetting on soil phosphorus (P) fractions and microbial community composition in regard to different fertilizer sources. Soil P dynamics and microbial community properties were evaluated in a soil not fertilized or fertilized with KHPO or swine manure at two temperatures (10 and 25 °C) and two soil water regimes (continuously moist and drying-rewetting cycles) in laboratory microcosm assays. The P source was the dominant factor determining the sizes of labile P fractions and microbial community properties. Manure fertilization increased the content of labile P, microbial biomass, alkaline phosphomonoesterase activity, and fatty acid contents, whereas KHPO fertilization increased the content of labile inorganic P and microbial P. Water regimes, second to fertilization in importance, affected more labile P pools, microbial biomass, alkaline phosphomonoesterase activity, and fatty acid contents than temperature. Drying-rewetting cycles increased labile P pools, decreased microbial biomass and alkaline phosphomonoesterase activity, and shaped the composition of microbial communities towards those with greater percentages of unsaturated fatty acids, particularly at 25 °C in manure-fertilized soils. Microbial C and P dynamics responded differentially to drying-rewetting cycles in manure-fertilized soils but not in KHPO-fertilized soils, suggesting their decoupling because of P sources and water regimes. Phosphorus sources, temperature, and water regimes interactively affected the labile organic P pool in the middle of incubation. Overall, P sources and water availability had greater effects on P dynamics and microbial community properties than temperature. [ABSTRACT FROM AUTHOR]

Microporous metal-organic frameworks (MOFs) that display permanent porosity show great promise for a myriad of purposes. The potential applications of MOFs can be developed further and extended by encapsulating various functional species (for example, nanoparticles) within the frameworks. However, despite increasing numbers of reports of nanoparticle/MOF composites, simultaneously to control the size, composition, dispersed nature, spatial distribution and confinement of the incorporated nanoparticles within MOF matrices remains a significant challenge. Here, we report a controlled encapsulation strategy that enables surfactant-capped nanostructured objects of various sizes, shapes and compositions to be enshrouded by a zeolitic imidazolate framework (ZIF-8). The incorporated nanoparticles are well dispersed and fully confined within the ZIF-8 crystals. This strategy also allows the controlled incorporation of multiple nanoparticles within each ZIF-8 crystallite. The as-prepared nanoparticle/ZIF-8 composites exhibit active (catalytic, magnetic and optical) properties that derive from the nanoparticles as well as molecular sieving and orientation effects that originate from the framework material. [ABSTRACT FROM AUTHOR]

Biochar shows great promise for use in adsorbing pollutants. However, a process for enhancing its adsorption capacity and re-collection efficiency is yet to be further developed. Hence, in this study, we developed a type of biochar coated with magnetic Fe3O4 nanoparticles (i.e., magnetic biochar (MBC)) and assessed its use for crystal violet (CV) adsorption as well as its recycling potential. The coating of Fe3O4 nanoparticles, which was not only on the surface, but also in the interior of biochar, performed two functions. Firstly, it produced a saturation magnetization of 61.48 emu/g, which enabled the biochar being efficiently re-collected using a magnet. Secondly, it significantly enhanced the adsorption capacity of the biochar (from 80.36 to 99.19 mg/g). The adsorption capacity of the MBC was determined to be the largest by so far (349.40 mg/g) for an initial CV concentration of 400 mg/L, pH of 6.0, and temperature of 40 °C, and the adsorption capacity of re-collected MBC was 73.31 mg/g. The adsorption of CV by the MBC was found to be a spontaneous and endothermic physical process in which the intraparticle diffusion was the limiting step. These findings inspire us to use other similar materials to tackle the menace of pollutions. [ABSTRACT FROM AUTHOR]

Mutualistic interactions in planktonic microbial communities have been extensively studied. However, our understanding on mutualistic communities consisting of co-existing planktonic cells and biofilms is limited. Here, we report a planktonic cells-biofilm mutualistic system established by the fermentative bacterium Escherichia coli and the dissimilatory metal-reducing bacterium Shewanella oneidensis in a bioelectrochemical device, where planktonic cells in the anode media interact with the biofilms on the electrode. Our results show that the transfer of formate is the key mechanism in this mutualistic system. More importantly, we demonstrate that the relative distribution of E. coli and S. oneidensis in the liquid media and biofilm is likely driven by their metabolic functions towards an optimum communal metabolism in the bioelectrochemical device. RNA sequencing-based transcriptomic analyses of the interacting organisms in the mutualistic system potentially reveal differential expression of genes involved in extracellular electron transfer pathways in both species in the planktonic cultures and biofilms. [ABSTRACT FROM AUTHOR]