Synergistic removal of total petroleum hydrocarbons and antibiotic resistance genes in Yellow River Delta wetlands contaminated soil composting regulated by biogas slurry addition.

The interactive effects between the emerging contaminant antibiotic resistance genes (ARGs) and the traditional pollutant total petroleum hydrocarbons (TPHs) in contaminated soils remain unclear. The synergistic removal of TPHs and ARGs from composted contaminated soil, along with the microbial mechanisms driven by the addition of biogas slurry, have not yet been investigated. This study explored the impact of biogas slurry on the synergistic degradation mechanisms and bacterial community dynamics of ARGs and TPHs in compost derived from contaminated soil. The addition of biogas slurry resulted in a reduction of targeted ARGs and mobile genetic elements (MGEs) by 9.96%-95.70% and 13.32%-97.66%, respectively. Biogas slurry changed the succession of bacterial communities during composting, thereby reducing the transmission risk of ARGs. Pseudomonas, Cellvibrio, and Devosia were identified as core microorganisms in the synergistic degradation of ARGs and TPHs. According to the partial least squares path model, temperature and NO3- indirectly influenced the removal of ARGs and TPHs by directly regulating the abundance and composition of host microbes and MGEs. In summary, the results of this study contribute to the high-value utilization of biogas slurry and provide methodological support for the low-cost remediation of contaminated soils.

Response of fulvic acid linking to redox characteristics on methane and short-chain fatty acids in anaerobic digestion of chicken manure.

Fulvic acids (FAs) is formed during the bioconversion of organic matter (OM) to biogas during anaerobic digestion (AD) and has a complex structure and redox function. However, the evolutionary mechanisms of FAs during AD and its interactions with acid and methane production have not been sufficiently investigated, especially at different stages of AD. Intermittent AD experiments by chicken manure and rice husk showed significant structural changes and reduced aromatization of FAs (e.g., O-H stretch6, 14.10-0%; SR, 0.22-0.60). The electron donating capacity (EDC) [9.76-45.39 µmole-/(g C)] and electron accepting capacity (EAC) [2.55-5.20 µmole-/(g C)] of FAs showed a tendency of decreasing and then increasing, and FAs had a stronger electron transfer capacity (ETC) in the methanogenic stage. Correlation analysis showed that the EDC of FAs was influenced by their own structure (C-O stretch2, C-H bend1, C-H bend4, and N-H bend) and also had an inhibitory effect on propionic production, which further inhibited acetic production. The EAC of FAs was affected by molecular weight and had a promoting effect on methane production. Structural equation modelling identified three possible pathways for AD. The C-O stretch2 structure of FAs alone inhibits the production of propionic. In addition, pH can directly affect the EDC of FAs. This study provides a theoretical basis for the structural and functional evolution of FAs in AD of chicken manure on the mechanism of methane production.

Linking Redox Characteristics to Dissolved Organic Matter Derived from Different Biowaste Composts: A Theoretical Modeling Approach Based on FT-ICR MS Analysis.

Compost dissolved organic matter (DOM) is a complex mixture of redox-active organic molecules that impact various biogeochemical processes in soil environments. However, the impact of chemical complexity (heterogeneity and chemodiversity) on the electron accepting capacity (EAC) and electron donating capacity (EDC) of DOM molecules remains unclear, which hinders our ability to predict their environmental behavior and redox properties. In this study, the applicability of Vienna Soil Organic Matter Modeler 2 (VSOMM2) to the composting system based on the FT-ICR MS data has been validated. A molecular modeling approach using VSOMM2 and Schrödinger software was developed to quantitatively assess the redox sites and molecular interactions of compost DOM. Compost DOM molecules are categorized into three distinct groups based on their heterogeneous origins. In addition, we have developed 18 molecular models of compost DOM based on the links of molecules to EAC/EDC. Finally, Ar-OH, quinone, Ar-SH, and Ar-NH2 were identified as the redox sites; noncovalent contacts, H bonds, salt bridges, and aromatic-H bonds might be significant electronic transmission channels of compost DOM. Our findings contribute to the development of precise regulatory methods for functional molecules within compost DOM, providing the fine standards for composts matching specific ecosystem service requirements.

Regulating method of microbial driving the phosphorus bioavailability in factory composting.

Phosphorus bioavailability is essential for assessing compost quality. However, the effects of microbial and environmental factors on potentially active phosphorus (H2O-P + NaHCO3-Pi) in factory compost have not been investigated. The findings indicated that chicken manure had significantly higher available phosphorus (AP) and H2O-P + NaHCO3-Pi throughout the composting process than kitchen waste (P < 0.05). Chicken manure compost also exhibited higher α-microbial diversity. Novibacillus, Marinococcaceae and Bacillales were the core bacteria involved in bioavailable phosphorus conversion in both composts. The core bacteria in kitchen waste compost had a broader range of phosphorus metabolism functions. Moreover, moisture and pH were the key environmental factors that significantly influenced the bioavailable phosphorus (P < 0.05). These findings provide a scientific foundation for regulating the composting process and improving phosphorus utilization efficiency.

Effect of microbial pretreatment on degradation of food waste and humus structure.

The study aimed to investigate the pretreatment characteristics of food waste (FW) by Bacillus licheniformis and Bacillus oryzaecorticis, and to determine the contribution of microbial hydrolysis in the structure of fulvic acid (FA) and humic acid (HA). FW was pretreated with Bacillus oryzaecorticis (FO) and Bacillus licheniformis (FL), and the resulting solution was heated to synthesize humus. The results showed that the acidic substances produced by microbial treatments led to a decrease in pH. In addition, Bacillus oryzaecorticis degraded starch and released a large amount of reducing sugar, providing OH and COOH to FA molecules. Bacillus licheniformis showed a positive effect on the HA structure, which had higher OH, CH3 and aliphatics. FO is more beneficial to retain OH and COOH, while FL is more beneficial to retain amino and aliphatics. This study provided evidence for the application of Bacillus licheniformis and Bacillus oryzaecorticis in waste management.

The key role of denitrification and dissimilatory nitrate reduction in nitrogen pollution along vertical landfill profiles from metagenomic perspective.

Landfill are persistent sources of nitrogen (N) pollution even in the decades after closure. However, the biological pathways of N-pollution, particularly N2O and NH4+, at different landfill depths have received little attention. In this study, metagenomic analysis was conducted on landfill refuse from vertical reservoir profiles in two closed landfills named XT and MT. NH4+ concentrations were found to be higher in deeper layers of MT, while greater potential for N2O emissions occurred in XT and the shallow layers of MT. Furthermore, the community structure and function of N-metabolizing microbes were more strongly defined by landfill depth than landfill type. Denitrification, involving abundant nirK and norB genes, was identified as the major pathway for N2O production in both XT and MT-shallow, while dissimilatory nitrate reduction with abundant nirBD genes was identified as the major pathway for NH4+ accumulation. Microbes of norB-type and nirBD-type were positively affected by NO3- in XT, whereas negatively affected by contents of organic material and moisture in MT-shallow. The mechanism by which nitrogen fixation, with abundant nifH genes, contributes to NH4+ accumulation in MT-deep should be further elucidated. These findings can provide a theoretical basis for governing scientific N-pollution control strategies throughout the entire landfill process.

MicroRNA-375 is a therapeutic target for castration-resistant prostate cancer through the PTPN4/STAT3 axis.

The functional role of microRNA-375 (miR-375) in the development of prostate cancer (PCa) remains controversial. Previously, we found that plasma exosomal miR-375 is significantly elevated in castration-resistant PCa (CRPC) patients compared with castration-sensitive PCa patients. Here, we aimed to determine how miR-375 modulates CRPC progression and thereafter to evaluate the therapeutic potential of human umbilical cord mesenchymal stem cell (hucMSC)-derived exosomes loaded with miR-375 antisense oligonucleotides (e-375i). We used miRNA in situ hybridization technique to evaluate miR-375 expression in PCa tissues, gain- and loss-of-function experiments to determine miR-375 function, and bioinformatic methods, dual-luciferase reporter assay, qPCR, IHC and western blotting to determine and validate the target as well as the effects of miR-375 at the molecular level. Then, e-375i complexes were assessed for their antagonizing effects against miR-375. We found that the expression of miR-375 was elevated in PCa tissues and cancer exosomes, correlating with the Gleason score. Forced expression of miR-375 enhanced the expression of EMT markers and AR but suppressed apoptosis markers, leading to enhanced proliferation, migration, invasion, and enzalutamide resistance and decreased apoptosis of PCa cells. These effects could be reversed by miR-375 silencing. Mechanistically, miR-375 directly interfered with the expression of phosphatase nonreceptor type 4 (PTPN4), which in turn stabilized phosphorylated STAT3. Application of e-375i could inhibit miR-375, upregulate PTPN4 and downregulate p-STAT3, eventually repressing the growth of PCa. Collectively, we identified a novel miR-375 target, PTPN4, that functions upstream of STAT3, and targeting miR-375 may be an alternative therapeutic for PCa, especially for CRPC with high AR levels.