Biodegradation of DEP, DIBP, and BBP by a psychrotolerant Sphingobium yanoikuyae strain P4: Degradation potentiality and mechanism study.

Phthalic acid esters (PAEs) are human made chemicals widely used as plasticizers to enhance the flexibility of plastic products. Due to the lack of chemical bonding between phthalates and plastics, these materials can easily enter the environment. Deleterious effects caused by this chemo-pollutant have drawn the attention of the scientific community to remediate them from different ecosystem. In this context, many bacterial strains have been reported across different habitats and Sphingobium yanoikuyae strain P4 is among the few psychrotolerant bacterial species reported to biodegrade simple and complex phthalates. In the present study, biodegradation of three structurally different PAEs viz., diethyl phthalate (DEP), di-isobutyl phthalate (DIBP), and butyl benzyl phthalate (BBP) have been investigated by the strain P4. Quantitative analyses through High-performance liquid chromatography (HPLC) revealed that the bacterium completely degraded 1 g/L of DEP, DIBP, and BBP supplemented individually in minimal media pH 7.0 within 72, 54, and 120 h of incubation, respectively, at 28 °C and under shake culture condition (180 rpm). In addition, the strain could grow in minimal media supplemented individually with up to 3 g/L of DEP and 10.0 g/L of DIBP and BBP at 28 °C and pH 7.0. The strain also could grow in metabolites resulting from biodegradation of DEP, DIBP, and BBP, viz. n-butanol, isobutanol, butyric acid, ethanol, benzyl alcohol, benzoic acid, phthalic acid, and protocatechuic acid. Furthermore, phthalic acid and protocatechuic acid were also detected as degradation pathway metabolites of DEP and DIBP by HPLC, which gave an initial idea about the biodegradation pathway(s) of these phthalates.

Evaluation of phthalate migration potential in vacuum-packed.

In recent years, the presence and migration of PAEs in packaging materials and consumer products has become a serious concern. Based on this concern, the aim of our study is to determine the possible migration potential and speed of PAEs in benthic fish stored in vacuum packaging, as well as to monitor the storage time and type as well as polyethylene (PE) polymer detection.As a result of the analysis performed by µ-Raman spectroscopy, 1 microplastic (MP) of 6 µm in size was determined on the 30th day of storage in whiting fish muscle and the polymer type was found to be Polyethylene (PE) (low density polyethylene: LDPE). Depending on the storage time of the packaging used in the vacuum packaging process, it has been determined that its chemical composition is affected by temperature and different types of polymers are formed. 10 types of PAEs were identified in the packaging material and stored flesh fish: DIBP, DBP, DPENP, DHEXP, BBP, DEHP, DCHP, DNOP, DINP and DDP. While the most dominant PAEs in the packaging material were determined as DEHP, the most dominant PAEs in fish meat were recorded as BBP and the lowest as DMP. The findings provide a motivating model for monitoring the presence and migration of PAEs in foods, while filling an important gap in maintaining a safe food chain.

Mitochondrial DNA Stress-Mediated Health Risk to Dibutyl Phthalate Contamination on Zebrafish (Danio rerio) at Early Life Stage.

Plastics contaminations are found globally and fit the exposure profile of the planetary boundary threat. The plasticizer of dibutyl phthalate (DBP) leaching has occurred and poses a great threat to human health and the ecosystem for decades, and its toxic mechanism needs further comprehensive elucidation. In this study, environmentally relevant levels of DBP were used for exposure, and the developmental process, oxidative stress, mitochondrial ultrastructure and function, mitochondrial DNA (mtDNA) instability and release, and mtDNA-cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) signaling pathway with inflammatory responses were measured in zebrafish at early life stage. Results showed that DBP exposure caused developmental impairments of heart rate, hatching rate, body length, and mortality in zebrafish embryo. Additionally, the elevated oxidative stress damaged mitochondrial ultrastructure and function and induced oxidative damage to the mtDNA with mutations and instability of replication, transcription, and DNA methylation. The stressed mtDNA leaked into the cytosol and activated the cGAS-STING signaling pathway and inflammation, which were ameliorated by co-treatment with DBP and mitochondrial reactive oxygen species (ROS) scavenger, inhibitors of cGAS or STING. Furthermore, the larval results suggest that DBP-induced mitochondrial toxicity of energy disorder and inflammation were involved in the developmental defects of impaired swimming capability. These results enhance the interpretation of mtDNA stress-mediated health risk to environmental contaminants and contribute to the scrutiny of mitochondrial toxicants.

Toxic mechanism in Daphnia magna due to phthalic acid esters and CuO nanoparticles co-exposure: The insight of physiological, microbiomic and metabolomic profiles.

Various phthalic acid esters (PAEs) such as dibutyl phthalate (DBP) and butyl benzyl phthalate (BBP) co-exist with nanopollutants in aquatic environment. In this study, Daphnia magna was exposed to nano-CuO and DBP or BBP at environmental relevant concentrations for 21-days to investigate these combined toxic effects. Acute EC50 values (48 h) of nano-CuO, DBP, and BBP were 12.572 mg/L, 8.978 mg/L, and 4.785 mg/L, respectively. Results showed that co-exposure with nano-CuO (500 µg/L) for 21 days significantly enhanced the toxicity of DBP (100 µg/L) and BBP (100 µg/L) to Daphnia magna by 18.37% and 18.11%, respectively. The activities of superoxide dismutase, catalase, and glutathione S-transferase were enhanced by 10.95% and 14.07%, 25.63% and 25.91%, and 39.93% and 35.01% in nano-CuO+DBP and nano-CuO+BBP treatments as compared to the individual exposure groups, verifying that antioxidative defense responses were activated. Furthermore, the co-exposure of nano-CuO and PAEs decreased the population richness and diversity microbiota, and changed the microbial community composition in Daphnia magna. Metabolomic analysis elucidated that nano-CuO + PAEs exposure induced stronger disturbance on metabolic network and molecular function, including amino acid, nucleotides, and lipid metabolism-related metabolic pathways, as comparison to PAEs single exposure treatments. In summary, the integration of physiological, microflora, and untargeted metabolomics analysis offers a fresh perspective into the potential ecological risk associated with nanopollutants and phthalate pollution in aquatic ecosystems.

Preparation of novel gallic acid-based dummy-template molecularly imprinted polymer adsorbents for rapid adsorption of dibutyl phthalate from water.

Phthalate esters (PAEs) are plasticizers widely used in the industry and easily released into the environment, posing a serious threat to human health. Molecularly imprinted polymers (MIPs) are important as selective adsorbents for the removal of PAEs. In this study, three kinds of mussel-inspired MIPs for the removal of PAEs were first prepared with gallic acid (GA), hexanediamine (HD), tannic acid (TA), and dopamine (DA) under mild conditions. The adsorption results showed that the MIP with low cost derived from GA and HD (GAHD-MIP) obtained the highest adsorption capacity among these materials. Furthermore, 97.43% of equilibrium capacity could be reached within the first 5 min of adsorption. Especially, the dummy template of diallyl phthalate (DAP) with low toxicity was observed to be more suitable to prepare MIPs than dibutyl phthalate (DBP), although DBP was the target of adsorption. The adsorption process was in accordance with the pseudo-second-order kinetics model. In the isotherm analysis, the adsorption behavior agreed with the Freundlich model. Additionally, the material maintained high adsorption performance after 7 cycles of regeneration tests. The GAHD-MIP adsorbents in this study, with low cost, rapid adsorption equilibrium, green raw materials, and low toxicity dummy template, provide a valuable reference for the design and development of new MIPs.

The combined neurotoxicity of DBP and nano-TiO2 in embryonic zebrafish (Danio rerio) revealed by oxidative activity, neuro-development genes expression and metabolomics changes.

Dibutyl phthalate (DBP) is a commonly used plasticizer that is frequently detected in water samples due to its widespread use. Titanium dioxide nanoparticles (n-TiO2) have been found to enhance the harmful effects of organic contaminants by increasing their bioavailability in aquatic environments. However, the combined toxic effects of DBP and n-TiO2 on aquatic organisms remain unclear. This study aimed to investigate the neurotoxicity of DBP and n-TiO2 synergistic exposure during the early life stage of zebrafish. The results of the study revealed that co-exposure of DBP and n-TiO2 led to an increase in deformities and a significant reduction in the active duration of zebrafish larvae. Furthermore, the co-exposure of DBP and n-TiO2 resulted in elevated levels of oxidative stress and altered gene expression related to neurodevelopment and apoptosis. Notably, n-TiO2 exacerbated the oxidative damage and apoptosis induced by DBP alone exposure. Additionally, co-exposure of the 1.0 mg/L DBP and n-TiO2 significantly affected the expression of genes associated with neurodevelopment. Moreover, disturbances in amino acid metabolism and interference with lipid metabolism were observed as a result of DBP and n-TiO2 co-exposure. In general, n-TiO2 aggravated the neurotoxicity of DBP in the early life stage of zebrafish by increasing oxidative stress, apoptosis, and disrupting amino acid synthesis and lipid metabolism. Therefore, it is essential to consider the potential risks caused by DBP and nanomaterials co-existence in the aquatic environment.

Molecular insights into the catabolism of dibutyl phthalate in Pseudomonas aeruginosa PS1 based on biochemical and multi-omics approaches.

A comprehensive understanding of the molecular mechanisms underlying microbial catabolism of dibutyl phthalate (DBP) is still lacking. Here, we newly isolated a bacterial strain identified as Pseudomonas aeruginosa PS1 with high efficiency of DBP degradation. The degradation ratios of DBP at 100-1000 mg/L by this strain reached 80-99 % within 72 h without a lag phase. A rare DBP-degradation pathway containing two monobutyl phthalate-catabolism steps was proposed based on intermediates identified by HPLC-TOF-MS/MS. In combination with genomic and transcriptomic analyses, we identified 66 key genes involved in DBP biodegradation and revealed the genetic basis for a new complete catabolic pathway from DBP to Succinyl-CoA or Acetyl-CoA in the genus Pseudomonas for the first time. Notably, we found that a series of homologous genes in Pht and Pca clusters were simultaneously activated under DBP exposure and some key intermediate degradation related gene clusters including Pht, Pca, Xyl, Ben, and Cat exhibited a favorable coexisting pattern, which contributed the high-efficient DBP degradation ability and strong adaptability to this strain. Overall, these results broaden the knowledge of the catabolic diversity of DBP in microorganisms and enhance our understanding of the molecular mechanism underlying DBP biodegradation.

Ultrasensitive, Label-Free Voltammetric Detection of Dibutyl Phthalate Based on Poly-l-lysine/poly(3,4-ethylenedioxythiophene)-porous Graphene Nanocomposite and Molecularly Imprinted Polymers.

Development of an efficient technique for accurate and sensitive dibutyl phthalate (DBP) determination is crucial for food safety and environment protection. An ultrasensitive molecularly imprinted polymers (MIP) voltammetric sensor was herein engineered for the specific determination of DBP using poly-l-lysine/poly(3,4-ethylenedioxythiophene)/porous graphene nanocomposite (PLL/PEDOT-PG) and poly(o-phenylenediamine)-imprinted film as a label-free and sensing platform. Fabrication of PEDOT-PG nanocomposites was achieved through a simple liquid-liquid interfacial polymerization. Subsequently, poly-l-lysine (PLL) functionalization was employed to enhance the dispersibility and stability of the prepared PEDOT-PG, as well as promote its adhesion on the sensor surface. In the presence of DBP, the imprinted poly(o-phenylenediamine) film was formed on the surface of PLL/PEDOT-PG. Investigation of the physical properties and electrochemical behavior of the MIP/PLL/PEDOT-PG indicates that the incorporation of PG into PEDOT, with PLL uniformly wrapping its surface, significantly enhanced conductivity, carrier mobility, stability, and provided a larger surface area for specific recognition sites. Under optimal experimental conditions, the electrochemical response exhibited a linear relationship with a logarithm of DBP concentration within the range of 1 fM to 5 µM, with the detection limit as low as 0.88 fM. The method demonstrated exceptional stability and repeatability and has been successfully applied to quantify DBP in plastic packaging materials.

Combined effect of polystyrene nanoplastic and di-n-butyl phthalate on testicular health of male Swiss albino mice: analysis of sperm-related parameters and potential toxic effects.

Plastics, especially polystyrene nanoplastic particles (PSNPs), are known for their durability and absorption properties, allowing them to interact with environmental pollutants such as di-n-butyl phthalate (DBP). Previous research has highlighted the potential of these particles as carriers for various pollutants, emphasizing the need to understand their environmental impact comprehensively. This study focuses on the subchronic exposure of male Swiss albino mice to PSNP and DBP, aiming to investigate their reproductive toxicity between these pollutants in mammalian models. The primary objective of this study is to examine the reproductive toxicity resulting from simultaneous exposure to PSNP and DBP in male Swiss albino mice. The study aims to analyze sperm parameters, measure antioxidant enzyme activity, and conduct histopathological and morphometric examinations of the testis. By investigating the individual and combined effects of PSNP and DBP, the study seeks to gain insights into their impact on the reproductive profile of male mice, emphasizing potential synergistic interactions between these environmental pollutants. Male Swiss albino mice were subjected to subchronic exposure (60 days) of PSNP (0.2 mg/m, 50 nm size) and DBP (900 mg/kg bw), both individually and in combination. Various parameters, including sperm parameters, antioxidant enzyme activity, histopathological changes, and morphometric characteristics of the testis, were evaluated. The Johnsen scoring system and histomorphometric parameters were employed for a comprehensive assessment of spermatogenesis and testicular structure. The study revealed non-lethal effects within the tested doses of PSNP and DBP alone and in combination, showing reductions in body weight gain and testis weight compared to the control. Individual exposures and the combination group exhibited adverse effects on sperm parameters, with the combination exposure demonstrating more severe outcomes. Structural abnormalities, including vascular congestion, Leydig cell hyperplasia, and the extensive congestion in tunica albuginea along with both ST and Leydig cell damage, were observed in the testis, underscoring the reproductive toxicity potential of PSNP and DBP. The Johnsen scoring system and histomorphometric parameters confirmed these findings, providing interconnected results aligning with observed structural abnormalities. The study concludes that simultaneous exposure to PSNP and DBP induces reproductive toxicity in male Swiss albino mice. The combination of these environmental pollutants leads to more severe disruptions in sperm parameters, testicular structure, and antioxidant defense mechanisms compared to individual exposures. The findings emphasize the importance of understanding the interactive mechanisms between different environmental pollutants and their collective impact on male reproductive health. The use of the Johnsen scoring system and histomorphometric parameters provides a comprehensive evaluation of spermatogenesis and testicular structure, contributing valuable insights to the field of environmental toxicology.

Analysis and remediation of phthalates in aquatic matrices: current perspectives.

Phthalic acid esters (PAEs) are high production volume chemicals used extensively as plasticizers, to increase the flexibility of the main polymer. They are reported to leach into their surroundings from plastic products and are now a ubiquitous environmental contaminant. Phthalate levels have been determined in several environmental matrices, especially in water. These levels serve as an indicator of plasticizer abuse and plastic pollution, and also serve as a route of exposure to different species including humans. Reports published on effects of different PAEs on experimental models demonstrate their carcinogenic, teratogenic, reproductive, and endocrine disruptive effects. Therefore, regular monitoring and remediation of environmental water samples is essential to ascertain their hazard quotient and daily exposure levels. This review summarises the extraction and detection techniques available for phthalate analysis in water samples such as chromatography, biosensors, immunoassays, and spectroscopy. Current remediation strategies for phthalate removal such as adsorption, advanced oxidation, and microbial degradation have also been highlighted.

Di-n-butyl phthalate promotes the neural differentiation of mouse embryonic stem cells through neurogenic differentiation 1.

An understanding of the risk of gene deletion and mutation posed by endocrine-disrupting chemicals (EDCs) is necessary for the identification of etiological reagents for many human diseases. Therefore, the characterization of the genetic traits caused by developmental exposure to EDCs is an important research subject. A new regenerative approach using embryonic stem cells (ESCs) holds promise for the development of stem-cell-based therapies and the identification of novel therapeutic agents against human diseases. Here, we focused on the characterization of the genetic traits and alterations in pluripotency/stemness triggered by phthalate ester derivatives. Regarding their in vitro effects, we reported the abilities of ESCs regarding proliferation, cell-cycle control, and neural ectoderm differentiation. The expression of their stemness-related genes and their genetic changes toward neural differentiation were examined, which led to the observation that the tumor suppressor gene product p53/retinoblastoma protein 1 and its related cascades play critical functions in cell-cycle progression, cell death, and neural differentiation. In addition, the expression of neurogenic differentiation 1 was affected by exposure to di-n-butyl phthalate in the context of cell differentiation into neural lineages. The nervous system is one of the most sensitive tissues to exposure to phthalate ester derivatives. The present screening system provides a good tool for studying the mechanisms underlying the effects of EDCs on the developmental regulation of humans and rodents, especially on the neuronal development of ESCs.

Biodegradation of phthalate acid esters and whole-genome analysis of a novel Streptomyces sp. FZ201 isolated from natural habitats.

Di-n-butyl phthalate (DBP) is one of the most extensively used phthalic acid esters (PAEs) and is considered to be an emerging, globally concerning pollutant. The genus Streptomyces holds promise as a degrader of various organic pollutants, but PAE biodegradation mechanisms by Streptomyces species remain unsolved. In this study, a novel PAE-degrading Streptomyces sp. FZ201 isolated from natural habitats efficiently degraded various PAEs. FZ201 had strong resilience against DBP and exhibited immediate degradation, with kinetics adhering to a first-order model. The comprehensive biodegradation of DBP involves de-esterification, ß-oxidation, trans-esterification, and aromatic ring cleavage. FZ201 contains numerous catabolic genes that potentially facilitate PAE biodegradation. The DBP metabolic pathway was reconstructed by genome annotation and intermediate identification. Streptomyces species have an open pangenome with substantial genome expansion events during the evolutionary process, enabling extensive genetic diversity and highly plastic genomes within the Streptomyces genus. FZ201 had a diverse array of highly expressed genes associated with the degradation of PAEs, potentially contributing significantly to its adaptive advantage and efficiency of PAE degradation. Thus, FZ201 is a promising candidate for remediating highly PAE-contaminated environments. These findings enhance our preliminary understanding of the molecular mechanisms employed by Streptomyces for the removal of PAEs.

Dibutyl phthalate (DBP) promotes Epithelial-Mesenchymal Transition (EMT) to aggravate liver fibrosis into cirrhosis and portal hypertension (PHT) via ROS/TGF-ß1/Snail-1 signalling pathway in adult rats.

OBJECTIVE: The primary objective of this study was to investigate the toxicological impact of Dibutyl phthalate (DBP) on the process of liver fibrosis transitioning into cirrhosis and the subsequent development of portal hypertension (PHT) through the mechanism of epithelial-mesenchymal transition (EMT) mediated by the ROS/TGF-ß/Snail-1 signaling pathway. METHOD: Carbon tetrachloride (CCl4) (1 mg/kg) was introduced in adult rats by oral feeding in CCl4 and CCl4+DBP groups twice a week for 8 weeks, and twice for another 8 week in CCl4 group. DBP was introduced by oral feeding in the CCl4+DBP group twice over the following 8 weeks. We subsequently analyzed hemodynamics measurements and liver cirrhosis degree, hepatic inflammation and liver function in the different groups. EMT related genes expression in rats in the groups of Control, DBP, CCl4 and CCl4+DBP were measured by immunohistochemistry (IHC). Enzyme-linked immunosorbent Assay (ELISA), qRT-PCR, western blot were used to detect the EMT related proteins and mRNA gene expression levels in rats and primary hepatocytes (PHCs). Reactive oxygen species (ROS) were examined with a ROS detection kit. RESULTS: The results showed that the CCl4+DBP group had higher portal pressure (PP) and lower mean arterial pressure (MAP) than the other groups. Elevated collagen deposition, profibrotic factor, inflammation, EMT levels were detected in DBP and CCl4+DBP groups. ROS, TGF-ß1 and Snail-1 were highly expressed after DBP exposure in vitro. TGF-ß1 had the potential to regulate Snail-1, and both of them were subject to regulation by ROS. CONCLUSION: DBP could influence the progression of EMT through its toxicological effect by ROS/TGF-ß1/Snail-1 signalling pathway, causing cirrhosis and PHT in final. The findings of this research might contribute to a novel comprehension of the underlying toxicological mechanisms and animal model involved in the progression of cirrhosis and PHT, and potentially offered a promising therapeutic target for the treatment of the disease.

Dibutyl phthalate exposure induced mitochondria-dependent ferroptosis by enhancing VDAC2 in zebrafish ZF4 cells.

Dibutyl phthalate (DBP) contamination has raised global concern for decades, while its health risk with toxic mechanisms requires further elaboration. This study used zebrafish ZF4 cells to investigate the toxicity of ferroptosis with underlying mechanisms in response to DBP exposure. Results showed that DBP induced ferroptosis, characterized by accumulation of ferrous iron, lipid peroxidation, and decrease of glutathione peroxidase 4 levels in a time-dependent manner, subsequently reduced cell viability. Transcriptome analysis revealed that voltage-dependent anion-selective channel (VDAC) in mitochondrial outer membrane was upregulated in ferroptosis signaling pathways. Protecting mitochondria with a VDAC2 inhibitor or siRNAs attenuated the accumulation of mitochondrial superoxide and lipid peroxides, the opening of mitochondrial permeability transition pore (mPTP), and the overload of iron levels, suggesting VDAC2 oligomerization mediated the influx of iron into mitochondria that is predominant and responsible for mitochondria-dependent ferroptosis under DBP exposure. Furthermore, the pivotal role of activating transcription factor 4 (ATF4) was identified in the transcriptional regulation of vdac2 by ChIP assay. And the intervention of atf4b inhibited DBP-induced VDAC2 upregulation and oligomerization. Taken together, this study reveals that ATF4-VDAC2 signaling pathway is involved in the DBP-induced ferroptosis in zebrafish ZF4 cells, contributing to the in-depth understanding of biotoxicity and the ecological risk assessment of phthalates.

Temporal evolution of plastic additive contents over the last decades in two major European rivers (Rhone and Rhine) from sediment cores analyses.

Although global plastic distribution is at the heart of 21st century environmental concerns, little information is available concerning how organic plastic additives contaminate freshwater sediments, which are often subject to strong anthropogenic pressure. Here, sediment core samples were collected in the Rhone and the Rhine watersheds (France), dated using 137Cs and 210Pbxs methods and analysed for nine phthalates (PAEs) and seven organophosphate esters (OPEs). The distribution of these organic contaminants was used to establish a chronological archive of plastic additive pollution from 1860 (Rhine) and 1930 (Rhone) until today. Sediment grain size and parameters related to organic matter (OM) were also measured as potential factors that may affect the temporal distribution of OPEs and PAEs in sediments. Our results show that OPE and PAE levels increased continuously in Rhone and Rhine sediments since the first records. In both rivers, ∑PAEs levels (from 9.1 ± 1.7 to 487.3 ± 27.0 ng g-1 dry weight (dw) ± standard deviation and from 4.6 ± 1.3 to 65.2 ± 11.2 ng g-1 dw, for the Rhine and the Rhone rivers, respectively) were higher than ∑OPEs levels (from 0.1 ± 0.1 to 79.1 ± 13.7 ng g-1 dw and from 0.6 ± 0.1 to 17.8 ± 2.3 ng g-1 dw, for Rhine and Rhone rivers, respectively). In both rivers, di(2-ethylhexyl) phthalate (DEHP) was the most abundant PAE, followed by diisobutyl phthalate (DiBP), while tris (2-chloroisopropyl) phosphate (TCPP) was the most abundant OPE. No relationship was found between granulometry and additives concentrations, while organic matter helps explain the vertical distribution of PAEs and OPEs in the sediment cores. This study thus establishes a temporal trajectory of PAEs and OPEs contents over the last decades, leading to a better understanding of historical pollution in these two Western European rivers.

[Microbial Mechanisms of Removal of Phthalic Acid Esters in Purple Soils Revealed Using Metagenomic Analysis].

The removal mechanisms of phthalic acid esters (PAEs) have attracted much attention because of their endocrine-disrupting properties and persistence in environmental media. In order to reveal the removal mechanism of PAEs and involved keystone taxa and functional genes, purple soils were polluted by di-n-butyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP), respectively, along a gradient of 0, 5, 10, and 20 mg·kg-1 and cultured for 90 days in the dark. The results showed that the degradation dynamics of DBP and DEHP were well-fitted by the first-order kinetic model, and the half-life of DBP and DEHP ranged from 17.0 to 38.2 days. The degradation rate of DBP (5 mg·kg-1) was the fastest, and that of DEHP (20 mg·kg-1) was the slowest. The soil samples of the seventh day and the fifteenth day were analyzed using metagenomic sequencing. NMDS and cluster analysis showed that there was a significant difference between the bacterial community structure of soil samples from the seventh day and the fifteenth day. The relative abundance of Actinobacteria increased from the seventh day to the fifteenth day. The smaller the half-life of DBP or DEHP, the higher the relative abundance of Actinobacteria in the different treatments. In addition, Streptomyces was the dominant genus in all polluted soils. Co-occurrence network analysis elucidated that Pandoraea was a keystone genus of the soil bacterial communities, which could be used to indicate the pollution levels of DBP and DEHP. The results of KEGG annotation demonstrated that Pandoraea was responsible for benzoate degradation, quorum sensing, ABC transporters, and the two-component system and could promote the intercellular communications and the microbial growth and proliferation and maintain the stability of the community structure. Therefore, the degradation rate of DBP and DEHP in purple soils depended on their initial content and their own properties. Actinobacteria played an important role in the PAEs degradation, and Pandoraea played a major part in promoting PAEs degradation and regulating the stability of the structure and function of degrading bacterial communities.

Assimilation of phthalate esters in bacteria.

The massive usage of phthalate esters (PAEs) has caused serious pollution. Bacterial degradation is a potential strategy to remove PAE contamination. So far, an increasing number of PAE-degrading strains have been isolated, and the catabolism of PAEs has been extensively studied and reviewed. However, the investigation into the bacterial PAE uptake process has received limited attention and remains preliminary. PAEs can interact spontaneously with compounds like peptidoglycan, lipopolysaccharides, and lipids on the bacterial cell envelope to migrate inside. However, this process compromises the structural integrity of the cells and causes disruptions. Thus, membrane protein-facilitated transport seems to be the main assimilation strategy in bacteria. So far, only an ATP-binding-cassette transporter PatDABC was proven to transport PAEs across the cytomembrane in a Gram-positive bacterium Rhodococcus jostii RHA1. Other cytomembrane proteins like major facilitator superfamily (MFS) proteins and outer membrane proteins in cell walls like FadL family channels, TonB-dependent transporters, and OmpW family proteins were only reported to facilitate the transport of PAEs analogs such as monoaromatic and polyaromatic hydrocarbons. The functions of these proteins in the intracellular transport of PAEs in bacteria await characterization and it is a promising avenue for future research on enhancing bacterial degradation of PAEs. KEY POINTS: • Membrane proteins on the bacterial cell envelope may be PAE transporters. • Most potential transporters need experimental validation.

Occurrence and prioritization of non-volatile substances in recycled PET flakes produced in China.

Recycled PET (rPET) is gaining popularity for use in the production of new food contact materials (FCMs) under the context of circular economy. However, the limited information on contaminants in rPET from China and concerns about their potential risk are major obstacles to their use in FCM in China. Fifty-five non-volatile compounds were tentatively identified in 126 batches of hot-washed rPET flakes aimed for food packaging applications in China. Although the 55 substances are not necessarily migratable and may not end up in the contacting media, their presence indicates a need for proper management and control across the value chain. For this reason, the 55 substances prioritized on the basis of level of concerns and in-silico genotoxicity profiler. Among them, dimethoxyethyl phthalate, dibutyl phthalate, bis(2-ethylhexyl) phthalate were classified as level V substances, and Michler's ketone and 4-nitrophenol were both categorized as level V substances and had the genotoxic structure alert, while 2,4,5-trimethylaniline was specified with genotoxic structure alert. The above substances have high priority and may pose a potential risk to human health, therefore special attention should be paid to their migration from rPET. Aside from providing valuable information on non-volatile contaminants present in hot-washed rPET flakes coming from China, this article proposed a prioritization workflow that can be of great help to identify priority substances deserving special attention across the value chain.

Exposure to the plasticizer dibutyl phthalate causes oxidative stress and neurotoxicity in brain tissue.

The phthalate ester, dibutyl phthalate (DBP), is one of the endocrine-disrupting chemicals detected in various aquatic environments. Previous research has found multiple toxic effects of DBP in aquatic organisms; however, the neurotoxic effects of the compound are surprisingly scanty. The purpose of this study was aimed to evaluate the role of oxidative stress in the induction of neurotoxicity in the brain tissue of the fish Pseudetroplus maculatus. The fish were exposed to the sublethal concentration of DBP (200 µg L-1) for 1, 4, 7, and 15 days along with control and vehicle control groups. The induction of oxidative stress in the brain subcellular fractions was proved by alterations in the activities of superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase along with the reduction in the total antioxidant capacity. Meanwhile, the levels of hydrogen peroxide and lipid peroxidation were increased. Neurotransmitters such as acetylcholine, dopamine, adrenaline, noradrenaline, and serotonin were altered in all subcellular fractions suggesting the disruption of the neurotransmitter system in the fish brain. These results indicate that DBP induces oxidative stress, which correlates with neurotoxicity in Pseudetroplus maculatus brain tissue.

Pollution characteristics, sources, and health risks of phthalate esters in ambient air: A daily continuous monitoring study in the central Chinese city of Nanchang.

In recent years, the atmospheric pollution caused by phthalate esters (PAEs) has been increasing due to the widespread use of PAE-containing materials. Existing research on atmospheric PAEs lacks long-term continuous observation and samples from cities in central China. To investigate the pollution characteristics, sources, and health risks of PAEs in the ambient air of a typical city in central China, daily PM2.5 samples were collected in Nanchang from November 2020 to October 2021. In this study, the detection and quantification of six significant PAE contaminants, namely diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), diisobutyl phthalate (DIBP), Di-2-ethylhexyl phthalate (DEHP), di-n-octyl phthalate (DnOP), and diisodecyl phthalate (DIDP), were accomplished using gas chromatography and mass spectrometry. The results revealed that the concentrations of DEP, DnBP, DEHP, and DnOP were relatively high. Higher temperatures promote the volatilization of PAEs, leading to an increase in the gaseous and particulate PAE concentrations in warm seasons and winter pollution scenarios. The results of principal component analysis show that PAEs mainly come from volatile products and polyvinylchloride plastics. Using positive matrix factorization analysis, it is shown that these two sources contribute 67.0% and 33.0% in atmosphere PAEs, respectively. Seasonally, the contribution of volatile products to both gaseous and particulate PAEs substantially increases during warm seasons. The residents in Nanchang exposed to PAEs have a negligible non-cancer risk and a potential low cancer risk. During the warm seasons, more PAEs are emitted into the air, which will increase the toxicity of PAEs and their impact on human health.