Effects of thermophilic bacteria inoculation on maturity, gaseous emission and bacterial community succession in hyperthermophilic composting.

Hyperthermophilic composting, characterized by temperatures equal to or exceeding 75 °C, offers superior compost maturity and performance. Inoculation with thermophilic bacteria presents a viable approach to achieving hyperthermophilic composting. This study investigates the effects of inoculating thermophilic bacteria, isolated at different temperatures (50 °C, 60 °C, and 70 °C) into compost on maturity, gaseous emissions, and microbial community dynamics during co-composting. Results indicate that the thermophilic bacteria inoculation treatments exhibited peak temperature on Day 3, with the maximum temperature of 75 °C reached two days earlier than the control treatment. Furthermore, these treatments demonstrated increased bacterial richness and diversity, along with elevated relative abundances of Firmicutes and Proteobacteria. They also fostered mutualistic correlations among microbial species, enhancing network connectivity and complexity, thereby facilitating lignocellulose degradation. Specifically, inoculation with thermophilic bacteria at 60 °C increased the relative abundance of Thermobifida and unclassified-f-Thermomonosporaceae (Actinobacteriota), whereas Bacillus, a thermophilic bacterium, was enriched in the 70 °C inoculation treatment. Consequently, the thermophilic bacteria at 60 °C and 70 °C enhanced maturity by 36 %-50 % and reduced NH3 emissions by 1.08 %-27.50 % through the proliferation of thermophilic heterotrophic ammonia-oxidizing bacteria (Corynebacterium). Moreover, all inoculation treatments decreased CH4 emissions by 6 %-27 % through the enrichment of methanotrophic bacteria (Methylococcaceae) and reduced H2S, Me2S, and Me2SS emissions by 1 %-25 %, 47 %-63 %, and 15 %-53 %, respectively. However, the inoculation treatments led to increased N2O emissions through enhanced denitrification, as evidenced by the enrichment of Truepera and Pusillimonas. Overall, thermophilic bacteria inoculation promoted bacteria associated with compost maturity while attenuating the relationship between core bacteria and gaseous emissions during composting.

A novel natural Syk inhibitor suppresses IgE-mediated mast cell activation and passive cutaneous anaphylaxis.

Spleen tyrosine kinase (Syk) plays a crucial role as a target for allergy treatment due to its involvement in immunoreceptor signaling. The purpose of this study was to identify natural inhibitors of Syk and assess their effects on the IgE-mediated allergic response in mast cells and ICR mice. A list of eight compounds was selected based on pharmacophore and molecular docking, showing potential inhibitory effects through virtual screening. Among these compounds, sophoraflavanone G (SFG) was found to inhibit Syk activity in an enzymatic assay, with an IC50 value of 2.2 µM. To investigate the conformational dynamics of the SYK-SFG system, we performed molecular dynamics simulations. The stability of the binding between SFG and Syk was evaluated using root mean square deviation (RMSD) and root mean square fluctuation (RMSF). In RBL-2H3 cells, SFG demonstrated a dose-dependent suppression of IgE/BSA-induced mast cell degranulation, with no significant cytotoxicity observed at concentrations below 10.0 µM within 24 h. Furthermore, SFG reduced the production of TNF-α and IL-4 in RBL-2H3 cells. Mechanistic investigations revealed that SFG inhibited downstream signaling proteins, including phospholipase Cγ1 (PLCγ1), as well as mitogen-activated protein kinases (AKT, Erk1/2, p38, and JNK), in mast cells in a dose-dependent manner. Passive cutaneous anaphylaxis (PCA) experiments demonstrated that SFG could reduce ear swelling, mast cell degranulation, and the expression of COX-2 and IL-4. Overall, our findings identify naturally occurring SFG as a direct inhibitor of Syk that effectively suppresses mast cell degranulation both in vitro and in vivo.

Application of atmospheric cold plasma for zearalenone detoxification in cereals: Kinetics, mechanisms, and cytotoxicity analysis.

INTRODUCTION: Zearalenone (ZEN) is one of the most widely contaminated mycotoxins in world, posing a severe threat to human and animal health. Atmospheric cold plasma (ACP) holds great penitential in mycotoxin degradation. OBJECTIVES: This study aimed to investigate the degradation efficiency and mechanisms of ACP on ZEN as well as the cytotoxicity of ZEN degradation products by ACP. Additionally, this study also investigated the degradation efficiency of ACP on ZEN in cereals and its effect on cereal quality. METHODS: The degradation efficiency and products of ZEN by ACP was analyzed by HPLC and LC-MS/MS. The human normal liver cells and mice were employed to assess the cytotoxicity of ZEN degradation products. The ZEN artificially contaminated cereals were used to evaluate the feasibility of ACP detoxification in cereals. RESULTS: The results showed that the degradation rate of ZEN was 96.18 % after 30-W ACP treatment for 180 s. The degradation rate was dependent on the discharge power, and treatment time and distance. Four major ZEN degradation products were produced after ACP treatment due to the oxidative destruction of CC double bond, namely C18H22O7 (m/z = 351.19), C18H22O8 (m/z = 367.14), C18H22O6 (m/z = 335.14), and C17H20O6 (m/z = 321.19). L02 cell viability was increased from 52.4 % to 99.76 % with ACP treatment time ranging from 0 to 180 s. Mice results showed significant recovery of body weight and depth of colonic crypts as well as mitigation of glomerular and liver damage. Additionally, ACP removed up to 50.55 % and 58.07 % of ZEN from wheat and corn. CONCLUSIONS: This study demonstrates that ACP could efficiently degrade ZEN in cereals and its cytotoxicity was significantly reduced. Therefore, ACP is a promising effective method for ZEN detoxification in cereals to ensure human and animal health. Future study needs to develop large-scale ACP device with high degradation efficiency.

Recent advances in the degradation efficacy and mechanisms of mycotoxins in food by atmospheric cold plasma.

Food contaminated by mycotoxins has become a worldwide public problem with political and economic implications. Although a variety of traditional methods have been used to eliminate mycotoxins from agri-foods, the results have been somewhat less than satisfactory. As an emerging non-thermal processing technology, atmospheric cold plasma (ACP) has great potential for food decontamination. Herein, this review mainly presents the degradation efficiency of ACP on mycotoxins in vitro and agri-foods as well as its possible degradation mechanisms. Meanwhile, ACP effects on food quality, factors affecting the degradation efficiency and the toxicity of degradation products are also discussed. According to the literatures, ACP could efficiently degrade many mycotoxins (e.g., aflatoxin, deoxynivalenol, zearalenone, ochratoxin A, fumonisin, and T-2 toxin) both in vitro and various foods (e.g., hazelnut, peanut, maize, rice, wheat, barley, oat flour, and date palm fruit) with little effects on the nutritional and sensory properties of food. The degradation efficacy was dependent on many factors including ACP treatment parameter, working gas, mycotoxin property, and food substrate. The mycotoxin degradation by ACP was mainly attributed to the reactive oxygen and nitrogen species in ACP, which can damage the chemical bonds of mycotoxins, consequently reducing the toxicity of mycotoxins.

Diatomic iron nanozyme with lipoxidase-like activity for efficient inactivation of enveloped virus.

Enveloped viruses encased within a lipid bilayer membrane are highly contagious and can cause many infectious diseases like influenza and COVID-19, thus calling for effective prevention and inactivation strategies. Here, we develop a diatomic iron nanozyme with lipoxidase-like (LOX-like) activity for the inactivation of enveloped virus. The diatomic iron sites can destruct the viral envelope via lipid peroxidation, thus displaying non-specific virucidal property. In contrast, natural LOX exhibits low antiviral performance, manifesting the advantage of nanozyme over the natural enzyme. Theoretical studies suggest that the Fe-O-Fe motif can match well the energy levels of Fe2 minority ß-spin d orbitals and pentadiene moiety π* orbitals, and thus significantly lower the activation barrier of cis,cis-1,4-pentadiene moiety in the vesicle membrane. We showcase that the diatomic iron nanozyme can be incorporated into air purifier to disinfect airborne flu virus. The present strategy promises a future application in comprehensive biosecurity control.

Inhibition of Fungal Growth and Aflatoxin B1 Synthesis in Aspergillus flavus by Plasma-Activated Water.

The gaseous reactive oxygen/nitrogen species (RONS) generated by cold atmospheric plasma (CAP) can effectively inactivate Aspergillus flavus (A. flavus) and prolong the shelf-life of food. Plasma-activated water (PAW) is the extension of cold plasma sterilization technology. Without the limitation of a plasma device, PAW can be applied to more scenarios of food decontamination. However, the efficacy of PAW as a carrier of RONS for eradicating A. flavus or inhibiting its growth remains unclear. In this study, the immediate fungicidal effect and long-term inhibitory effect of PAW on A. flavus were investigated. The results demonstrated that 60-min instant-prepared PAW could achieve a 3.22 log reduction CFU/mL of A. flavus and the fungicidal efficacy of PAW gradually declined with the extension of storage time. Peroxynitrite (ONOO-/ONOOH) played a crucial role in this inactivation process, which could damage the cell wall and membrane structure, disrupt intracellular redox homeostasis, and impair mitochondrial function, ultimately leading to fungal inactivation. In addition to the fungicidal effect, PAW also exhibited fungistatic properties and inhibited the synthesis of aflatoxin B1 (AFB1) in A. flavus. By analyzing the cellular antioxidant capacity, energy metabolism, and key gene expression in the AFB1 synthesis pathway, it was discovered that PAW can significantly reduce ATP levels, while increasing SOD and CAT activity during 5-d cultivation. Meanwhile, PAW effectively suppressed the expression of genes related to AFB1 synthesis.

Dynamics of antibiotic resistance genes and bacterial community during pig manure, kitchen waste, and sewage sludge composting.

Organic solid wastes (OSWs) are important reservoirs for antibiotic resistance genes (ARGs). Aerobic composting transforms OSWs into fertilizers. In this study, we investigated ARGs dynamics and their driving mechanisms in three OSW composts: pig manure (PM), kitchen waste (KC), and sewage sludge (SG). The dominant ARGs were different in each OSW, namely tetracycline, aminoglycoside, and macrolide resistance (PM); tetracyclines and aminoglycosides (KC); and sulfonamides (SG). ARGs abundance decreased in PM (71%) but increased in KC (5.9-fold) and SG (1.3-fold). Interestingly, the ARGs abundance was generally similar in all final composts, which was contributed to the similar bacterial community in final composts. In particular, sulfonamide and ß-lactam resistant genes removed (100%) in PM, while sulfonamide in KC (38-fold) and tetracycline in SG (5-fold) increased the most. Additionally, ARGs abundance rebounded during the maturation period in all treatments. Firmicutes, Proteobacteria, and Actinobacteria were the main ARGs hosts. Several persistent and high-risk genes included tetW, aadA, aadE, tetX, strB, tetA, mefA, intl1, and intl2. The structural equation models showed ARGs removal was mainly affected by physicochemical parameters and bacterial communities in PM, the ARGs enrichment in KC composting correlated with increased mobile genetic elements (MGEs). In general, thermophilic aerobic composting can inhibit the vertical gene transfer (VGT) of pig manure and horizontal gene transfer (HGT) of sludge, but it increases the HGT of kitchen waste, resulting in a dramatic increase of ARGs in KC compost. More attention should be paid to the ARGs risk of kitchen waste composting.

Comparative analysis of helium and air surface micro-discharge plasma treatment on the microbial reduction and quality attributes of beef slices.

This work aimed to compare the effects of helium and air surface micro-discharge (SMD) plasma on the microbial safety and quality of beef tissues. For the beef tissue model, the concentration and diffusion depth of hydroxyl radical and ozone have different change patterns over plasma treatment time and distance in helium and air SMD plasma. The inactivation efficiency of helium plasma depended on the plasma treatment time and distance, while the inactivation efficiency of air plasma only depended on the treatment time. For the fresh beef slices, air SMD plasma treatment exhibited a higher antimicrobial activity against S. aureus and E. coli than helium SMD plasma treatment (1.5 versus 0.9; 0.9 versus 0.28 log CFU/g at 10 min). However, air SMD plasma treatment caused more adverse effects on beef quality, leading to a smooth surface, extensive lipid oxidation, protein structure damage, low pH and discoloration compared to helium SMD plasma treatment. This work provides valuable guidelines for the working gas choice in the practical application of plasma to meat decontamination.

The Role of Reactive Oxygen Species in Plant Response to Radiation.

Radiation is widespread in nature, including ultraviolet radiation from the sun, cosmic radiation and radiation emitted by natural radionuclides. Over the years, the increasing industrialization of human beings has brought about more radiation, such as enhanced UV-B radiation due to ground ozone decay, and the emission and contamination of nuclear waste due to the increasing nuclear power plants and radioactive material industry. With additional radiation reaching plants, both negative effects including damage to cell membranes, reduction of photosynthetic rate and premature aging and benefits such as growth promotion and stress resistance enhancement have been observed. ROS (Reactive oxygen species) are reactive oxidants in plant cells, including hydrogen peroxide (H2O2), superoxide anions (O2•-) and hydroxide anion radicals (·OH), which may stimulate the antioxidant system of plants and act as signaling molecules to regulate downstream reactions. A number of studies have observed the change of ROS in plant cells under radiation, and new technology such as RNA-seq has molecularly revealed the regulation of radiative biological effects by ROS. This review summarized recent progress on the role of ROS in plant response to radiations including UV, ion beam and plasma, and may help to reveal the mechanisms of plant responses to radiation.

Extracellular enzyme stoichiometry and microbial resource limitation following various grassland reestablishment in abandoned cropland.

Grassland restoration in abandoned cropland had great impact on soil enzyme stoichiometry and microbial resource limitation, hence altering carbon (C) sequestration progress in soil depending on soil depth and grassland restoration strategy. It is crucial to understand the microbial resource limitation under various restoration strategies, which could have key implication for optimizing management to improve C sequestration in abandoned cropland. The objective of this study was to examine the changes and key regulators of soil enzyme stoichiometry and microbial resource limitation in different soil depths under different management strategies to restore grassland, namely a) cropland as continuous cropping (CR); b) naturally restored grassland (NR); c) grass-based grassland (GG); d) legume-based grassland (LG); e) grass-legume mixed grassland (MG); and f) grass-based grassland with N fertilization (GF). Results showed that converting cropland into grassland increased absolute soil enzyme activities potential for microbial C, nitrogen (N) and phosphorus (P) acquisition by 5-110 %, 25-132 % and 17-215 %, respectively depending on soil depth and grassland restoration strategy. These enzyme activities increased more in surface soil than subsoil with the conversion of cropland into grassland, especially under LG and GF. The strategies to restore grassland, especially LG and GF, significantly decreased enzymatic C:P and N:P ratios. Microbial C limitation was reduced associated with re-establishment of grassland, exacerbating the P limitation depending on grassland restoration strategies, especially under LG and GF. The shift of relative microbial resource limitation from C to P reduced the microbial C use efficiency, reducing the ecosystem C sequestration potential during the restoration of grassland. It appears that increased biomass input and soil C:P ratio are the key drivers to shift microbial resource limitation from C to P during the restoration of grassland. Thus, a moderate harvest of above-ground biomass with a supplement of P may be necessary for improving the C sequestration potential during the restoration of grasslands, especially in the grass-legume mix or grass-based grassland with N fertilization.

Effect of moisture content, aeration rate, and C/N on maturity and gaseous emissions during kitchen waste rapid composting.

To determine factors affecting compost maturity and gaseous emissions during the rapid composting of kitchen waste, an orthogonal test was conducted with three factors: moisture content (MC) (55%, 60%, 65%), aeration rate (AR) (0.3,0.6 and 0.9 L·kg-1DM·min-1) and C/N ratio (21, 24, 27). The results showed that the importance of factors affecting compost maturity was: C/N > AR > MC, optimal conditions were: C/N of 24, AR of 0.3 L·kg-1DM·min-1and MC of 65%. For gaseous emissions, the sequence of essential factors affecting NH3 emissions was: C/N > MC > AR, and the optimal parameters for NH3 reduction were: C/N of 27, MC of 65%, and AR of L·kg-1DM·min-1. The important factors affecting N2O and H2S emissions are both: MC > C/N > AR, while their best parameters were different. The optimal parameters for N2O emission reduction were MC of 60%, AR of 0.3 L·kg-1DM·min-1 and C/N of 24, while these for H2S were MC of 55%, AR of 0.3 L·kg-1DM·min-1 and C/N of 21. The C/N mainly affected the compost maturity and AR further affected the maturity and pollutant gas emissions by influencing the temperature and O2 content. Considering comprehensively the maturity and gaseous reduction, the optimal control parameters were: MC of 60%-65%, AR of L·kg-1DM·min-1, and C/N of 24-27.

A Manganese-Based Metal-Organic Framework as a Cold-Adapted Nanozyme.

The development of cold-adapted enzymes with high efficiency and good stability is an advanced strategy to overcome the limitations of catalytic medicine in low and cryogenic temperatures. In this work, inspired by natural enzymes, a novel cold-adapted nanozyme based on a manganese-based nanosized metal-organic framework (nMnBTC) is designed and synthesized. The nMnBTC as an oxidase mimetic not only exhibits excellent activity at 0 °C, but also presents almost no observable activity loss as the temperature is increased to 45 °C. This breaks the traditional recognition that enzymes show maximum activity only under specific psychrophilic or thermophilic condition. The superior performance of nMnBTC as a cold-adapted nanozyme can be attributed to its high-catalytic efficiency at low temperature, good substrate affinity, and flexible conformation. Based on the robust performance of nMnBTC, a low-temperature antiviral strategy is developed to inactivate influenza virus H1N1 even at -20 °C. These results not only provide an important guide for the rational design of highly efficient artificial cold-adapted enzymes, but also pave a novel way for biomedical application in cryogenic fields.

Phytotoxicity of farm livestock manures in facultative heap composting using the seed germination index as indicator.

Static facultative heap composting of animal manure is widely used in China, but there is almost no systematic research on the phytotoxicity of the produced compost. Here, we evaluated the phytotoxic variation in compost produced by facultative heap composting of four types of animal manure (chicken manure, pig manure, sheep manure, and cattle manure) using different plant seeds (cucumber, radish, Chinese cabbage, and oilseed rape) to determine germination index (GI). The key factors that affected GI values were identified, including the dynamics of the phytotoxicity and microbial community during heap composting. Sensitivity to toxicity differed depending on the type of plant seed used. Phytotoxicity during facultative heap composting, evaluated by the GI, was in the order: chicken manure (0-6.6 %) < pig manure (14.4-90.5 %) < sheep manure (46.0-93.0 %) < cattle manure (50.2-105.8 %). Network analysis showed that the volatile fatty acid (VFA) concentration was positively correlated with Firmicutes abundance, and NH4+-N was correlated with Actinobacteria, Proteobacteria, and Bacteroidetes. More bacteria were stimulated to participate in conversions of dissolved organic carbon, dissolved nitrogen, VFA, and ammonia-nitrogen (NH4+-N) in sheep manure heap composting than that in other manure. The GI was most affected by VFA in chicken manure and cattle manure heap composting, while NH4+-N was the main factor affecting the GI in pig manure and sheep manure compost. The dissolved carbon and nitrogen content and composition, as well as the core and proprietary microbial communities, were the primary factors that affected the succession of phytotoxic substances in facultative heap composting, which in turn affected GI values. In this study, the key pathways of livestock manure composting that affected GI and phytotoxicity were found and evaluated, which provided new insights and theoretical support for the safe use of organic fertilizer.

Regulation of cellular redox homeostasis in Arabidopsis thaliana seedling by atmospheric pressure cold plasma-generated reactive oxygen/nitrogen species.

Atmospheric pressure cold plasma (APCP) holds great potential as an efficient, economical and eco-friendly approach for improving crop production. Although APCP-induced plant growth promotion is undisputedly attributed to the reactive oxygen and nitrogen species (RONS), how these RONS regulate the intracellular redox state and plant growth is still largely unknown. This study systematically investigates the regulation mechanism of APCP-generated RONS on intracellular redox homeostasis in Arabidopsis thaliana seedling by measuring the RONS compositions in APCP-treated solutions and intracellular RONS and antioxidants in Arabidopsis seedlings. The results show that APCP exhibited a dual effect (stimulation or inhibition) on Arabidopsis seedling growth dependent on the treatment time. APCP-generated RONS in liquids increased in a time-dependent manner, leading to an increase of conductivity and oxidation reduction potential (ORP) and decrease of pH. APCP caused an enrichment of intracellular RONS and most of them increased with APCP treatment time. Meanwhile, APCP treatment accelerated malondialdehyde (MDA) generation, and the level of intracellular antioxidants were enhanced by low-dose APCP treatment while decreased at high doses. The results of correlation analysis showed that the extracellular RONS produced by APCP were positively correlated with the intracellular RONS and negatively correlated with the antioxidants. These results demonstrate that the improved antioxidant capacity induced by moderate APCP-generated RONS plays an important role in the growth promotion of Arabidopsis seedlings, which may be a promising alternative for fertilizers in agricultural production.

Co-composting of kitchen waste with agriculture and forestry residues and characteristics of compost with different particle size: An industrial scale case study.

Since the implementation of domestic waste classification in China, the kitchen waste production has increased rapidly. The unique physical and chemical properties of kitchen waste make it impossible for direct composting for composting alone. This study investigated the co-composting of kitchen waste with agriculture and forest residues at an industrial scale at the Nangong Composting Plant (Located in Beijing). Cornstalks, garden waste, and watermelon seedlings were composted with kitchen waste, with the added agriculture and forestry residues comprising 5%, 10% and 20% of the weight. Industrial composting was performed 30 days at a scale of 165-180 tone. The mixed compost products were screened to different particle sizes, and the maturity, humification, and calorific value were analyzed. The kitchen waste mixed with 20% agricultural complementary materials reached hyperthermophilic temperature (82 °C), had reduced moisture content (45%), and resulted in better composting performance at an industrial scale. By adding 20% complementary materials to kitchen waste produced mature compost with a higher germination index (GI) (91%) by adjusting the pH, electrical conductivity (EC), carbon to nitrogen ratio (C/N), and moisture content. The compost in the 5% and 10% complementary materials treatments did not fully mature and had a GI of<10%, influenced by the higher EC and NH4+-N content. The property of final compost with different particle size vary greatly. The small particle size compost (≤45 mm) had higher uniformity, maturity, and humification degree, and it was suitable to use as a fertilizer; the larger particle size (>45 mm) had more material with lower calorific value (8000-10,000 kJ·kg-1), and could be used as refuse-derived fuel. To make better use of kitchen waste compost, 45-mm particle size screening is suggested at an industrial-scale composting plant. These results support industrial-scale kitchen waste composting in China.

Effects of phosphate-containing additives and zeolite on maturity and heavy metal passivation during pig manure composting.

This study investigated the effects of the combination of phosphogypsum with calcium oxide (PPG + CaO), superphosphate with calcium oxide (SSP + CaO) and zeolite (Zeolite) on composting maturity and heavy metal passivation in pig manure composting. The results showed that all treatments reached the maturity requirements and the phosphorus-containing additive treatments had higher final germination indices (GIs). Compared with CK, additive treatments enhanced the compost maturity by promoting volatile fatty acids (VFAs) decomposition (26.4%-30.5%) and formation of stable humus substances. All additive amendment treatments increased humic acid-like substances by over 20%, and the PPG + CaO treatment had the highest level of humus. Composting process reduced the bioavailability of Cu (49.2%), Cd (5.0%), Cr (54.3%), and Pb (26.6%). Correlation analysis found that the heavy mental passivation rate was significantly negatively correlated with the contents of VFAs and nitrogenous substances, and positively correlated with the pH, GI, humic acid content and the ratio of humic acid to fulvic acid (HA/FA). Therefore, the PPG + CaO treatment further increased the passivation rates of Cu (65.6%), Cd (21.7%), and Pb (48.7%) and decreased the mobilization of Zn by promoting maturity and humification during composting.

Effective control of microbial spoilage in soybeans by water-soluble ZnO nanoparticles.

The microbial spoilage of soybeans during soaking process severely deteriorates the quality of soybean products and threatens human health. Herein, water-soluble aminated zinc oxide nanoparticles (ZnO NPs) were developed to effectively control the microbial spoilage in soybeans during soaking. ZnO NPs achieved significant inactivation of three dominant spoilage bacteria (bacillus cereus, bacillus megaterium and enterococcus faecium) isolated from the deteriorated soybeans, which could adhere to the bacterial surface and damage the cell wall/membrane, but also generate large amounts of reactive oxygen species (ROS). Compared to two commercial ZnO, water-soluble ZnO exhibited superior antibacterial properties due to producing more ROS and bacteria-adhered ability. After ZnO NPs treatment, the content of the residual Zn (51.1 mg/kg) in soybeans was the safety standards of Zn element in soybeans products for human). Therefore, the water-soluble ZnO NPs showed great potentials as efficient and safe antimicrobial agents for soybeans preservation during soaking process.

Composting temperature directly affects the removal of antibiotic resistance genes and mobile genetic elements in livestock manure.

The high antibiotic resistance gene (ARGs) contents in livestock manure pose a potential risk to environment and human health. The heap composting with an ambient temperature and thermophilic composting are two methods for converting livestock manure into fertilizer. This study investigated the variations in ARGs and mobile genetic elements (MGEs) and revealed potential mechanisms for ARGs removal using the two composting methods. The ARGs abundance were enriched by 44-fold in heap composting, among them, the macrolide-resistance genes increased significantly. On the contrary, the ARGs were removed by 92% in thermophilic composting, among them, tetracycline-resistance genes decreased by 97%. The bacterial hosts of ARGs were associated with the variations of ARGs and MGEs. The tetO was correlated with the most diverse bacteria in heap composting, and Bacteroidetes was the major host bacteria. While tetT was correlated with the most diverse bacteria in thermophilic composting, and Proteobacteria was the major host bacteria. Structural equation models showed that the enrichment of ARGs in heap composting was mainly correlated with bacterial communities, whereas, the removal of ARGs in thermophilic composting was directly affect by MGEs. Composting temperature directly affected the variations in ARGs. Higher and lower temperatures significantly decreased and increased, respectively, ARGs and MGEs abundance levels.

Ferroptotic stress promotes macrophages against intracellular bacteria.

Rational: Intracellular bacterial survival is a major factor causing chronic or recurrent infection, leading to the failure of both host defense and/or antibiotic treatment. However, the elimination of intracellular bacteria is challenging as they are protected from antibiotics and host immune attack. Recent studies have indicated that iron helps macrophages against intracellular bacteria, contradictory to traditional "nutritional immunity", in which iron is considered a key nutrient for bacterial survival in host cells. However, how iron facilitates intracellular bacterial death has not been fully clarified. In this study, we found that ferroptotic stress can help macrophages suppress intracellular bacteria by reversing the importation of ferrous iron into bacterial vacuoles via ferroportin and thereby inducing in situ ferroptosis-like bacterial death. Methods: A macrophage model of bacterial invasion was established to monitor dynamic changes in ferroptotic hallmarks, including ferrous iron and lipid peroxidation. Ferroptosis inducers and inhibitors were added to the model to evaluate the relationship between ferroptotic stress and intracellular bacterial survival. We then determined the spatiotemporal distributions of ferroportin, ferrous iron, and lipid peroxidation in macrophages and intracellular bacteria. A bacterial infection mouse model was established to evaluate the therapeutic effects of drugs that regulate ferroptotic stress. Results: Ferrous iron and lipid peroxidation increased sharply in the early stage of bacterial infection in the macrophages, then decreased to normal levels in the late stage of infection. The addition of ferroptosis inducers (ras-selective lethal small molecule 3, sulfasalazine, and acetaminophen) in macrophages promoted intracellular bacterial suppression. Further studies revealed that ferrous iron could be delivered to the intracellular bacterial compartment via inward ferroportin transportation, where ferrous iron induced ferroptosis-like death of bacteria. In addition, ferroptotic stress declined to normal levels in the late stage of infection by regulating iron-related pathways in the macrophages. Importantly, we found that enhancing ferroptotic stress with a ferroptosis inducer (sulfasalazine) successfully suppressed bacteria in the mouse infection models. Conclusions: Our study suggests that the spatiotemporal response to ferroptosis stress is an efficient pathway for macrophage defense against bacterial invasion, and targeting ferroptosis may achieve therapeutic targets for infectious diseases challenged by intracellular pathogens.

Superphosphate, biochar, and a microbial inoculum regulate phytotoxicity and humification during chicken manure composting.

The germination index (GI) is the best index for evaluating compost phytotoxicity and maturity. In order to improve GI and reduce phytotoxicity of chicken manure compost, superphosphate, biochar, and a microbial inoculum were added in this study. Maturity indices (pH, electrical conductivity, and GI), water-soluble ion, organic matter, humic acid, humic precursor contents, and the bacteria community were analyzed during the experiment. NH4+, volatile fatty acids, and humic acid strongly affected the GI, which increased as the humic acid content increased and the volatile fatty acid and NH4+ contents decreased. The three additives affected compost maturity differently. Adding biochar decreased microbial diversity and complexity, but improved the GI mainly by affecting abiotic factors. Adding the microbial inoculum increased biotic activity and promoted humus and precursor formation. Superphosphate activated core functional bacteria and increased bacterial diversity and complexity, and 16 genera and 2 phyla (Gemmatimonadota and Chloroflexi) were found only in this composting pile. Superphosphate markedly accelerated humification and decreased the salt (NH4+ and NO3-) and heavy metal ion (Cu2+, Cd2+, Cr3+) contents, forming stable substances to reduce the key phytotoxic matters, which in turn decreased the compost phytotoxicity and improved the GI. These results provide a new sight for promoting maturity by functional material regulation in composting.