Improved sea rice yield and accelerated di-2-ethylhexyl phthalate (DEHP) degradation by straw carbonization returning in coastal saline soils

Key genes and microbial ecological clusters involved in organophosphate ester degradation in agricultural fields of a typical watershed in southwest China

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers, and they have raised global concern due to their persistence, bioaccumulation, and potential toxicity. However, OPE contamination characteristics and microbial degradation mechanisms in agricultural soils remain poorly understood. This study investigated agricultural soils from the riparian zone of the Anning River Basin in southwest China. The concentrations of 12 OPEs were determined using gas chromatography-tandem mass spectrometry. The results revealed that the total OPE concentration was moderate, with triethyl phosphate being the most abundant compound. Metagenomic techniques and Bayesian linear regression analysis were employed in combination with the Kyoto Encyclopedia of Genes and Genomes database to identify potential degradation pathways for triethyl phosphate and tris (2-chloroethyl) phosphate. The phoA, phoB, phoD, and glpQ genes, which encode phosphatases, catalyze ester bond cleavage, thereby facilitating the degradation of OPEs. Further microbial interaction network analysis identified core OPE-degrading microorganisms, including Pimelobacter simplex, Nocardioides sp. JS614, Nocardioides daphniae, and Methylocystis heyeri. Additionally, neutral community models indicated that environmental selection drives microbial community structure. In conclusion, this study provides an in-depth understanding of OPE contamination and its microbial degradation mechanisms in agricultural soils, offering theoretical insights for pollution management and remediation strategies.

Characterization of modified rape straw biochar in immobilizing Aspergillus sydowii W1 pellets and evaluation on its role as a novel composite for di(2-ethylhexyl) phthalate degradation

Di(2-ethylhexyl) phthalate (DEHP) is one of the most widely used plasticizers, which has harmful biological effects and poses a serious threat to ecological environments and human health. In this study, a novel strain Aspergillus sydowii W1 was reported with DEHP degradation ability. Under the optimal conditions of 35°C and pH 6.0, strain W1 degraded 68.48 % of 50 mg/L DEHP within 120 h, while the biochar immobilized W1 can enhance the removal efficiency by 15.33 %. The immobilized W1 also showed excellent performance in DEHP polluted wastewater with concentration of 50 mg/L, and its removal rate reached 85.72 % within 144 h. Interestingly, the fermented broth of strain W1 has the activity of hydrolyzing DEHP, and the highest value of crude enzyme activity was at 35°C and pH 8.5. In addition, nine metabolic products of DEHP degraded by strain W1 were identified by HPLC-MS/MS and GC-MS. In combination with these intermediates and related enzymatic analysis, two possible catabolism pathways of DEHP degradation by strain W1 were concluded. This study confirmed that immobilized W1 is an effective composite for removing DEHP in water environment and also strengthened our understanding on the DEHP degradation process of A. sydowii.

Insight into natural attenuation of tributyl phosphate by indigenous anaerobic microbes in soils: Implication by stable carbon isotope fractionation and microbial community structures

Organophosphate esters (OPEs) are widespread in the environment, with high persistence and toxicity. However, the underlying mechanisms of anaerobic microbial degradation of OPEs remain elusive in the field environment. In this study, the natural attenuation mechanisms of tributyl phosphate (TnBP) by indigenous anaerobic microorganisms in soils were investigated by using compound-specific stable isotope analysis (CSIA) and characterization of microbial communities. The results indicated that dibutyl phosphate (DnBP) was the major degradation product of TnBP. Significant carbon isotope fractionation was observed for TnBP during the anaerobic microbial degradation, and the carbon isotope enrichment factor (εC) was determined to be -2.71 ± 0.13‰. Unlike aerobic degradation with P-O bond cleavage, C-O bond cleavage was verified as the mode to removal a butyl side chain for TnBP to generate DnBP during the anaerobic microbial degradation. Microbial community analysis indicated that Sphingomonans, Nocardioides and Streptomyces were the important contributors to microbial degradation of TnBP in anoxic soils. TnBP altered microbial metabolic functions in anoxic soils, mainly enhancing the biosynthesis of ansamycins, ketone bodies and amino acids, and flagellar assembly, which promoted microbial degradation of TnBP. This study provided a better method to characterize the chemical bond cleavage mode and effect of OPEs on microbial communities, which was a prerequisite for the bioremediation of OPE pollution in soils.

The occurrence and safety evaluation of phthalic acid esters in Oasis agricultural soils of Xinjiang, China

Soil pollution caused by plastic residues containing additives (e.g. phthalic acid esters (PAEs)) is ubiquitous and has become a global concern. However, the distribution, accumulation, and potential risks associated with PAEs in agricultural soils have not been fully explored. This study quantified the types, concentrations, and distribution patterns of common PAEs in 29 agricultural soil samples collected from the Xinjiang Oasis, China. The results indicated that no significant variation in PAE concentrations across the oasis farmlands in Xinjiang. The PAEs were predominantly concentrated in the topsoil layer (0-20 cm), with an average concentration of 102.3 μg/kg, with some migration observed to the deeper soil layer (20-40 cm). The most abundant PAEs detected were Di (2-ethylhexyl) phthalate (DEHP), diisobutyl phthalate (DIBP), and diethyl phthalate (DEP), which accounted for 49.82 %, 23.74 %, and 20.96 % of the total, respectively. Furthermore, the concentrations of all PAEs were below China's soil quality risk control standards, and the non-carcinogenic risks to both adults and children were below the current threshold, indicating relatively low risks to both the human health and the environment. These findings are crucial for understanding the presence and safety evaluation of PAEs in Xinjiang Oasis farmland, and they provide important reference data for managing and controlling PAE contamination in agricultural soils.

Biodegradation of Di-2-Ethylhexyl Phthalate by Mangrove Sediment Microbiome Impacted by Chronic Plastic Waste

Plastic pollution through the leaching of di(2-ethylhexyl) phthalate (DEHP), a widely used plasticizer, has led to the emergence of mangrove pollution. This study aimed to assess the DEHP removal efficiency of indigenous mangrove sediment microbiomes and identify key DEHP degraders using microcosm construction and metagenomic analysis. During the 35-day incubation period, the indigenous mangrove sediment microbiome, affected by chronic plastic pollution, demonstrated a 99% degradation efficiency of 200 mg/kg DEHP. Spearman's correlation analysis suggested that Myxococcales, Methyloligellaceae, Mycobacterium, and Micromonospora were potentially responsible for DEHP degradation. Based on PICRUSt2, the DEHP-degrading pathway in the sediment was predicted to be an anaerobic process involving catechol metabolism through catC, pcaD, pcaI, pcaF, and fadA. Efficient bacterial isolates from the mangrove sediment, identified as Gordonia sp. and Gordonia polyisoprenivorans, were able to degrade DEHP (65-97%) within 7 days and showed the ability to degrade other phthalate esters (PAEs).

Biochar regulates the functions of keystone taxa to reduce p-coumaric acid accumulation in soil

Introduction

Applying biochar (BC) to reduce toxic substance accumulation in soil, either through direct adsorption or modulation of the microbial community, has received considerable attention. However, a knowledge gap exists regarding how BC regulates microbial community structure and functions to mitigate toxic substance accumulation.

Methods

We previously identified p-coumaric acid (p-CA) as a representative autotoxin in tobacco rhizosphere soil. On this basis, this study simulated a soil environment with p-CA accumulation to investigate the impacts of BC on p-CA, soil physicochemical properties, and microbial community structure and function.

Results

The results showed that p-CA could be directly adsorbed onto BC, which followed the pseudo-second-order kinetic model (R 2 = 0.996). A pot experiment revealed that BC significantly reduced soil p-CA, altered soil microbial composition, and enhanced bacterial community diversity. A weighted correlation network analysis showed a close association between taxon 1 in the microbial network and p-CA, suggesting a pivotal role for this taxon in reducing p-CA, with Devosia and Nocardioides identified as potential key contributors to this process. The prediction of possible keystone taxa functions showed that BC increased the relative abundances of aromatic compound degraders. Mantel tests indicated that soil organic matter exerted the greatest influence on keystone taxa functions and hub genera.

Discussion

These findings suggest that BC may either directly chemisorb p-CA or indirectly facilitate p-CA degradation by regulating the functioning of keystone taxa. The results of this study provide a novel perspective for further investigation of the mechanisms through which BC reduces the accumulation of toxic substances in soil.

Novel insights into DEHP-induced zebrafish spleen damage: Cellular apoptosis, mitochondrial dysfunction, and innate immunity

DEHP (Di(2-ethylhexyl) phthalate) is the most abundant phthalate component detected in environmental samples as it is widely used in the manufacturing of children's toys, medical devices and furniture. Due to its wide prevalence and propensity to accumulate in the food chain, significant concerns have risen about the safety profile of DEHP. Here, we used a zebrafish model to investigate the toxicity mechanisms of DEHP. Our results indicated that exposure to DEHP altered the ROS content in zebrafish spleen and inhibited the activities of antioxidant enzymes SOD and CAT, detoxification enzyme GSH-Px and induced histopathological damage. In addition, elucidated the mechanism of DEHP significantly promoted apoptosis and caused damage in spleen cells through the bax/bcl-2 pathway. Further genetic testing demonstrated significant alterations in mitochondrial biogenesis, fission, and fusion-related genes and suggested potential mechanistic pathways, including GM10532/m6A/FIS1 axis, the STAT3/POA1 axis, and the NFR1/TFAM axis. Serological and genomic analysis indicated that DEHP exposure activated the C3 complement cascade immune pathway and interfered with innate immune function. IBRv2 analysis proposes that innate immunity may serve as a signal indicator of early toxic responses to DEHP pollutants. This study provided comprehensive cellular and genetic data for DEHP toxicity studies and emphasized the need for future management and remediation of DEHP contamination. It also provides data to specifically support the health risk assessments of DEHP, as well as contributing to broader health and environmental research.