Evaluation of electrokinetic-assisted phytoremediation efficiency of dibutyl phthalate contaminated soil by maize (Zea mays L.) under different electric field intensities.

The excessive accumulation of dibutyl phthalate (DBP) in soil poses a serious threat to soil ecosystems and crop safety production. Electrokinetic-assisted phytoremediation (EKPR) has been considered as a potential technology for remediating organic contaminated soils. In order to investigate the effect of different electric fields on removal efficiency of DBP, three kinds of electric fields were set up in this study (1 V·cm-1, 2 V·cm-1 and 3 V·cm-1). The results showed that 59 % of DBP in soil was removed by maize (Zea mays L.) within 20 d in low-intensity electric field (1 V·cm-1), and the accumulation of DBP in maize tissues decreased significantly compared to the non-electrified treatment group. Interestingly, it could be observed that the low-intensity electric field could maintain ion homeostasis and improve the photosynthetic efficiency of the plant, thereby relieving the inhibition of DBP on plant growth and increasing the chlorophyll content (94.1 %) of maize. However, the removal efficiency of DBP by maize decreased significantly under the medium-intensity (2 V·cm-1) and high-intensity electric field (3 V·cm-1). Moreover, the important roles of soil enzyme and rhizosphere bacterial community in low-electric field were also investigated and discussed. This study provided a new perspective for exploring the mechanism of removing DBP through EKPR.

Improving key gene expression and di-n-butyl phthalate (DBP) degrading ability in a novel Pseudochrobactrum sp. XF203 by ribosome engineering.

Di-n-butyl phthalate (DBP) is one of the important phthalates detected commonly in soils and crops, posing serious threat to human health. Pseudochrobactrum sp. XF203 (XF203), a new strain related with DBP biodegradation, was first identified from a natural habitat lacking human disturbance. Genomic analysis coupled with gene expression comparison assay revealed this strain harbors the key aromatic ring-cleaving gene catE203 (encoding catechol 2,3-dioxygenase/C23O) involved DBP biodegradation. Following intermediates identification and enzymatic analysis also indicated a C23O dependent DBP lysis pathway in XF203. The gene directed ribosome engineering was operated and to generate a desirable mutant strain XF203R with highest catE203 gene expression level and strong DBP degrading ability. The X203R removed DBP in soil jointly by reassembling bacterial community. These results demonstrate a great value of XF203R for the practical DBP bioremediation application, highlighting the important role of the key gene-directed ribosome engineering in mining multi-pollutants degrading bacteria from natural habitats where various functional genes are well conserved.

Human skin absorption of three phthalates.

Population studies reveal widespread exposure to phthalates. Understanding their absorption, distribution, metabolism, and excretion is vital to reduce exposure. However, data on skin absorption remain limited. We thus aim to characterize the skin permeation of three phthalates in a mixture, neat or in emulsion; di(2-ethylhexyl) phthalate (d4-DEHP), dibutyl phthalate (d4-DBP), and diethyl phthalate (d4-DEP), by comparing in vitro human skin (800 µm) permeation (24 hours) results using flow-through diffusion cells with urine results obtained from volunteers exposed to the same mixture applied to a forearm (40 cm2). Metabolites were analyzed in receptor fluids and urine. Phthalates crossed the skin barrier and metabolized into monoesters before elimination. Increased permeation was observed for phthalates in emulsion compared to neat substances, with polyethylene glycol (PEG) in the receptor fluid enhancing emulsion permeation, but not affecting neat substances. In vitro results mirrored in vivo findings: DEP showed rapid permeation (J: ∼2 ug/cm2/h) and urinary excretion peaking at six hours post-application, whereas DBP exhibited slower kinetics (J: ∼0.1 ug/cm2/h), with a urinary peak at 15-17 hours post-application. DEHP had minimal permeation (J: ∼0.0002 ug/cm2/h) with no observable urinary peak. These findings underscore the importance of comprehending phthalate skin absorption for effective exposure mitigation strategies.

Antioxidant defenses and metabolic responses of Mytilus coruscus exposed to various concentrations of PAEs (phthalate esters).

Phthalate esters (PAEs), as a major plasticizer with multi-biotoxicity, are frequently detected in marine environments, and potentially affecting the survival of aquatic organisms. In the study, three typical PAEs (dimethyl phthalate [DMP], dibutyl phthalate [DBP] and di(2-ethylhexyl) phthalate [DEHP]) were selected to investigate the accumulation patterns and ecotoxicological effects on Mytilus coruscus (M. coruscus). In M. coruscus, the accumulation was DEHP>DBP>DMP, and the bioaccumulation in tissues was digestive glands>gills>gonads>muscles. Meanwhile, the activities of superoxide dismutase (SOD) and catalase (CAT) showed an activation-decrease-activation trend of stress, with more pronounced concentration effects. Glutathione reductase (GSH) activity was significantly increased, and its expression was more sensitive to be induced at an early stage. The metabolic profiles of the gonads, digestive glands and muscle tissues were significantly altered, and DEHP had a greater effect on the metabolic profiles of M. coruscus, with the strongest interference. PAEs stress for 7 d significantly altered the volatile components of M. coruscus, with potential implications for their nutritional value. This study provides a biochemical, metabolomic, and nutritional analysis of DMP, DBP, and DEHP toxic effects on M. coruscus from a multidimensional perspective, which provides support for ecotoxicological studies of PAEs on marine organisms. ENVIRONMENTAL IMPLICATION: Phthalate esters (PAEs), synthetic compounds from phthalic acid, are widespread in the environment, household products, aquatic plants, animals, and crops, posing a significant threat to human health. However, the majority of toxicological studies examining the effects of PAEs on aquatic organisms primarily focus on non-economic model organisms like algae and zebrafish. Relatively fewer studies have been conducted on marine organisms, particularly economically important shellfish. So, this study is innovative and necessary. This study provides a biochemical, metabolomic, and nutritional analysis of DMP, DBP, and DEHP toxic effects on mussels, and supports the ecotoxicology of PAEs on marine organisms.

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.

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.

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 degradation by Paenarthrobacter ureafaciens PB10 through downstream product myristic acid and its bioremediation potential in contaminated soil.

Dibutyl phthalate (DBP) is a widely used plasticizer to make plastic flexible and long-lasting. It is easily accessible in a broad spectrum of environments as a result of the rising level of plastic pollution. This compound is considered a top-priority toxicant and persistent organic pollutant by international environmental agencies for its endocrine disruptive and carcinogenic propensities. To mitigate the DBP in the soil, one DBP-degrading bacterial strain was isolated from a plastic-polluted landfill and identified as Paenarthrobacter ureafaciens PB10 by 16S rRNA gene sequence-based homology. The strain was found to develop a distinct transparent halo zone around grown colonies on an agar plate supplemented with DBP. The addition of yeast extract (100 mg/L) as a nutrient source accelerated cell biomass production and DBP degradation rate; however, the presence of glucose suppressed DBP degradation by the PB10 strain without affecting its ability to proliferate. The strain PB10 was efficient in eliminating DBP under various pH conditions (5.0-8.0). Maximum cell growth and degradation of 99.49% at 300 mg/L DBP were achieved in 72 h at the optimized mineral salt medium (MS) conditions of pH 7.0 and 32 °C. Despite that, when the concentration of DBP rose to 3000 mg/L, the DBP depletion rate was measured at 79.34% in 72 h. Some novel intermediate metabolites, like myristic acid, hexadecanoic acid, stearic acid, and the methyl derivative of 4-hydroxyphenyl acetate, along with monobutyl phthalate and phthalic acid, were detected in the downstream degradation process of DBP through GC-MS profiling. Furthermore, in synchronization with native soil microbes, this PB10 strain successfully removed a notable amount of DBP (up to 54.11%) from contaminated soil under microcosm study after 10 d. Thus, PB10 has effective DBP removal ability and is considered a potential candidate for bioremediation in DBP-contaminated sites.

Dibutyl phthalate disrupts glycogen synthase kinase 3α essential for sperm motility.

To unravel the toxic mechanism of phthalate ester plasticizer endocrine disruptor in spermatozoa, we examined the effect of dibutyl phthalate (DBP) on the stability and inhibitory phosphorylation of glycogen synthase kinase 3α (GSK3α), a protein kinase crucial for sperm motility in mice. In DBP-treated spermatozoa, reactive oxygen species (ROS) and lipid peroxide were significantly increased. In computer-assisted sperm analysis, DBP at concentrations of 10 - 100 µg/mL significantly decreased total motility and progressive motility of spermatozoa. On western blots, DBP decreased p-GSK3α(Ser21) and increased p-GSK3α(Tyr279) in spermatozoa. Similarly, hydrogen peroxide decreased p-GSK3α(Ser21) but not p-GSK3α(Tyr279) in spermatozoa. Immunofluorescent labeling demonstrated that DBP markedly decreased immunoreactivities of GSK3α and p-GSK3α(Ser21) but increased immunoreactivity of p-GSK3α(Tyr279) in spermatozoa. DBP at a concentration of 100 µg/mL significantly increased phosphatase activity in spermatozoa. Calyculin A, a protein phosphatase 1 and 2 A inhibitor, markedly increased p-GSK3α(Ser21) and sperm motility and attenuated a DBP-induced decrease of p-GSK3α(Ser21) and sperm motility. On western blot, 1-100 µg/mL DBP decreased GSK3α in spermatozoa. On immunoprecipitation western blot, DBP at 10 - 100 µg/mL increased polyubiquitinated sperm proteins including GSK3α. The MG115, proteasome inhibitor attenuated degradation of GSK3α in DBP-treated spermatozoa. Hydrogen peroxide at 10 µM increased polyubiquitinated sperm proteins, suggesting that DBP may increase ubiquitination of GSK3α via ROS induction. Together, DBP may decrease the cellular amount of GSK3α through the ubiquitin-proteasome pathway and p-GSK3α(Ser21) through ROS generation and activation of protein phosphatases, impairing sperm motility.

Activated DBP degradation and relevant signal transduction path via quorum sensing autoinducers in Streptomyces sp. SH5.

Microbe-mediated DBP (dibutyl phthalate) mineralization is acknowledged to be affected by diverse extracellular factors. However, little is known about the regulatory effects from quorum sensing (QS) signals. In this study, extracellularly applied QS signals A-like (hydroxymethyl dihydrofuran) was discovered to significantly enhance DBP degradation efficiency in Streptomyces sp. SH5. Monobutyl phthalate, protocatechuic acid and beta-ketoadipate were discovered as degradation intermediates by HPLC-TOF-MS/MS. Multi-omics analysis revealed the up-regulation of multiple hydrolases, transferases and decarboxylases that potentially contributed to A-like accelerated DBP degradation. Transcription of Orf2708, an orthologue of global transcriptional activator, was significantly induced by A-like. Orf2708 was demonstrated to interact specifically with the promoter of hydrolase orf2879 gene by EMSA, and the overexpression of orf2879 led to an enhanced DBP degradation in SH5. Taken together with the molecular docking studies showing the stability of ligand-receptor complex of A-like and its potential receptor Orf3712, a hierarchical regulatory cascade underlying the QS signal mediated DBP degradation was proposed as A-like/Orf3712 duplex formation, enhanced orf2708 expression and the downstream specific activation of hydrolase Orf2879. Our study presents the first evidence of GBLs-type promoted DBP degradation among bacteria, and the elucidated signal transduction path indicates a universal application potential of this activation strategy.

Optimizing concentration and interaction mechanism of Demodesmus sp. and Achromobacter pulmonis sp. consortium to evaluate their potential for dibutyl phthalate removal from synthetic wastewater.

A green approach of Desmodesmus sp. to Achromobacter pulmonis (1:1) coculture ratios was optimized to improve the removal efficiency of dibutyl phthalate (DBP) from simulated wastewater. High DBP resistance bacterial strains and microalgae was optimized from plastic contaminated water and acclimation process respectively. The influence of various factors on DBP removal performance was comprehensively investigated. Highest DBP removal 93 % was recorded, when the ratios algae-bacteria 1:1, with sodium acetate, pH-6, shaking speed-120 rpm and lighting periods L:D-12:12. Enough nutrient (TN/TP/TOC) availability and higher protein-108 mg/L and sugar-40 mg/L were observed in presences of 50 mg/L DBP. The degradation and sorption were calculated 81,12; 27,39 & 43,12 % in algae-bacteria, only algae and only bacteria system respectively. The degradation kinetics t1/2 3.74,22.15,12.86 days were evaluated, confirming that algae-bacteria effectively degrade the DBP. This outcome leading to promote a green sustainable approach to remove the emerging contamination from wastewater.

Complete degradation of di-n-butyl phthalate by Glutamicibacter sp. strain 0426 with a novel pathway.

Di-n-butyl phthalate (DBP) is widely used as plasticizer that has potential carcinogenic, teratogenic, and endocrine effects. In the present study, an efficient DBP-degrading bacterial strain 0426 was isolated and identified as a Glutamicibacter sp. strain 0426. It can utilize DBP as the sole source of carbon and energy and completely degraded 300 mg/L of DBP within 12 h. The optimal conditions (pH 6.9 and 31.7 °C) for DBP degradation were determined by response surface methodology and DBP degradation well fitted with the first-order kinetics. Bioaugmentation of contaminated soil with strain 0426 enhanced DBP (1 mg/g soil) degradation, indicating the application potential of strain 0426 for environment DBP removal. Strain 0426 harbors a distinctive DBP hydrolysis mechanism with two parallel benzoate metabolic pathways, which may account for the remarkable performance of DBP degradation. Sequences alignment has shown that an alpha/beta fold hydrolase (WP_083586847.1) contained a conserved catalytic triad and pentapeptide motif (GX1SX2G), of which function is similar to phthalic acid ester (PAEs) hydrolases and lipases that can efficiently catalyze hydrolysis of water-insoluble substrates. Furthermore, phthalic acid was converted to benzoate by decarboxylation, which entered into two different pathways: one is the protocatechuic acid pathway under the role of pca cluster, and the other is the catechol pathway. This study demonstrates a novel DBP degradation pathway, which broadens our understanding of the mechanisms of PAE biodegradation.

Comparing the removal efficiency of diisobutyl phthalate by Bacillariophyta, Cyanophyta and Chlorophyta.

The utilization of microalgae for both removing phthalate esters (PAEs) from wastewater and producing bioenergy has become a popular research topic. However, there is a lack of studies comparing the effectiveness of different types of microalgae in removing these harmful compounds. Therefore, the present study aimed to evaluate and compare the efficiency of various processes, such as hydrolysis, photolysis, adsorption, and biodegradation, in removing diisobutyl phthalate (DiBP) using six different species of microalgae. The study indicated that the average removal efficiency of DiBP (initial concentrations of 5, 0.5, and 0.05 mg L-1) by all six microalgae (initial cell density of 1 × 106 cells mL-1) was in the order of Scenedesmus obliquus (95.39 %) > Chlorella vulgaris (94.78 %) > Chroococcus sp. (91.16 %) > Cyclotella sp. (89.32 %) > Nitzschia sp. (88.38 %) > Nostoc sp. (84.33 %). The results of both hydrolysis and photolysis experiments revealed that the removal of DiBP had minimal impact, with respective removal efficiencies of only 0.89 % and 1.82 %. The adsorption efficiency of all six microalgae decreased significantly with increasing initial DiBP concentrations, while the biodegradation efficiency was elevated. Chlorella vulgaris and Chroococcus sp. demonstrated the highest adsorption and biodegradation efficiencies among the microalgae tested. Scenedesmus obliquus was chosen for the analysis of the degradation products of DiBP due to its exceptional ability to remove DiBP. The analysis yielded valuable results, identifying monoisobutyl phthalate (MiBP), phthalic acid (PA), and salicylic acid (SA) as the possible degradation products of DiBP. The possible degradation pathways mainly included dealkylation, the addition of hydroxyl groups, and decarboxylation. This study lays a theoretical foundation for the elimination of PAEs in the aquatic environment.

Curcumin strengthens a spontaneous self-protective mechanism-SP1/PRDX6 pathway, against di-n-butyl phthalate-induced testicular ferroptosis damage.

As one of the common plasticizers, di-n-butyl phthalate (DBP) has been using in various daily consumer products worldwide. Since it is easily released from products and exists in the environment for a long time, it has a lasting impact on human health, especially male reproductive health. However, the detailed mechanism of testicular damage from DBP and the protection strategy are still not clear enough. In this study, we found that DBP could induce dose-dependent ferroptosis in testicular tissue. Mechanism dissection indicates that DBP can upregulate SP1 expression, which could directly transcriptionally upregulate PRDX6, a negative regulator of ferroptosis. Overexpression of PRDX6 or adding SP1 agonist curcumin could suppress the DBP-induced ferroptosis on testicular cells. In vivo, rats were given 500 mg/kg/day DBP orally for 3 weeks; elevated levels of ferroptosis were detected in testicular tissue. When the above-mentioned doses of DBP and curcumin at a dose of 300 mg/kg/day were administered intragastrically simultaneously, the testicular ferroptosis induced by DBP was alleviated. Immunohistochemistry and quantitative real-time PCR of testis tissue showed that the expression of PRDX6 was upregulated under the action of DBP and curcumin. These findings suggest a spontaneous self-protection mechanism of testicular tissue from DBP damage by upregulating SP1 and PRDX6. However, it is not strong enough to resist the DBP-induced ferroptosis. Curcumin can strengthen this self-protection mechanism and weaken the level of ferroptosis induced by DBP. This study may help us to develop a novel therapeutic option with curcumin to protect the testicular tissue from ferroptosis and function impairment by DBP.

Combined exposure to multiwalled carbon nanotubes and dibutyl phthalates aggravated airway inflammation in rats.

Previous work has shown that mice exposed to dibutyl phthalate (DBP) adsorbed onto multi-walled carbon nanotubes (MWCNTs), via tail vein injection, displayed black lesions in their lungs. To investigate the mechanism causing this toxicity in the lung tissue, we performed an experiment with rats, exposing them to DBP adsorbed onto MWCNTs via a tail vein injection for 14 days. The results revealed pulmonary edema and greyish-black lung tissue in the MWCNTs and the MWCNTs + DBP combined exposure groups. In the combined exposure group there was evident alveolar fragmentation and adhesion, and lung tissue sections showed significant levels of black particles. Sections of the non-cartilaginous region of the trachea had significant folding of the pseudostratified ciliated columnar epithelium and marked thickening of the submucosa. In broncho alveolar lavage fluid, the number of leukocytes (WBC), lymphocytes (Lym), neutrophils (Neu), and eosinophils (Eos), as well as levels of immunoglobulin E (IgE), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), and interleukin 1ß (IL-1ß) were all significantly higher. TNF-α, IL-6, signal transducer and activator of transcription 3 (STAT3), and α-smooth muscle actin (α-SMA) mRNA expression were all elevated in the lung tissue. The combined exposure group, which had considerable airway remodeling, had a greater degree of tracheal constriction and luminal narrowing, according to the results of the α-SMA immunofluorescence assay. According to these experimental findings, the exposure to both MWCNTs and DBP seemed to have a synergistic effect and exacerbated rats' impaired respiratory function that resulted from exposure to MWCNTs alone.

Insights into molecular mechanism of plasticizer biodegradation in Dietzia kunjamensis IITR165 and Brucella intermedia IITR166 isolated from a solid waste dumpsite.

AIMS: Isolation of phthalate esters (PAEs) degrading bacteria from a solid waste dumpsite could degrade many plasticizers efficiently and to investigate their degrading kinetics, pathways, and genes. METHODS AND RESULTS: Based on their 16S rRNA gene sequence the strains were identified as Dietzia kunjamensis IITR165 and Brucella intermedia IITR166, which showed a first-order degradation kinetic model under lab conditions. The quantification of phthalates and their intermediate metabolites identification were done by using ultra-high-performance liquid chromatography (UHPLC) and gas chromatography-tandem mass-spectrometry (GC-MS/MS), respectively. Both the bacteria utilized >99% dibutyl phthalate at a high concentration of 100-400 mg L-1 within 192 h as monitored by UHPLC. GC-MS/MS revealed the presence of metabolites dimethyl phthalate (DMP), phthalic acid (PA), and benzoic acid (BA) during DBP degradation by IITR165 while monobutyl phthalate (MBP) and PA were identified in IITR166. Phthalate esters degrading gene cluster in IITR165 comprised two novel genes coding for carboxylesterase (dkca1) and mono-alkyl phthalate hydrolase (maph), having only 37.47% and 47.74% homology, respectively, with reported phthalate degradation genes, along with the terephthalate dioxygenase system (tphA1, A2, A3, and B). However, IITR166 harbored different gene clusters comprising di-alkyl phthalate hydrolase (dph_bi), and phthalate dioxygenase (ophA, B, and C) genes. CONCLUSIONS: Two novel bacterial strains, Dietzia kunjamensis IITR165 and Brucella intermedia IITR166, were isolated and found to efficiently degrade DBP at high concentrations. The degradation followed first-order kinetics, and both strains exhibited a removal efficiency of over 99%. Metabolite analysis revealed that both bacteria utilized de-methylation, de-esterification, and decarboxylation steps during degradation.

Enhanced removal of dibutyl phthalate in a laccase-mediator system: Optimized process parameters, kinetics, and environmental impact.

The persistence and recalcitrance of endocrine-disrupting chemicals (EDCs) in the environment have raised momentous concerns due to their carcinogenic, teratogenic, genotoxic, and cytotoxic effects on humans, animals, and plants. Unarguably, dibutyl phthalate (DBP) is one of the most ubiquitous EDCs because of its bioavailability in water, soil, and atmosphere. This study aims to investigate the efficiency of Agaricus bisporus laccase in the degradation of dibutyl phthalate (DBP) in laccase-mediator system. Here, enhanced removal efficiency was recorded during DBP degradation in laccase-mediator systems than in reaction medium containing laccase only. About 98.85% of 30 mg L-1 DBP was efficiently removed in a medium containing 1.3 U mL-1, 0.045 mM Syringaldehyde (SYR) at incubation temperature 30 aC and pH 5 within 24 h. This finding was further corroborated by the synergistic interplay of the optimal parameters in the laccase-SYR system done using response surface methodology (Box-Behnken Design). Furthermore, the addition of 1.5 mM of metal ions in the laccase-SYR system further promoted the enhanced removal of DBP in the following order: Cr3+> Pb2+> Ca2+> Al3+>Zn2+ > Cu2+. A significant decrease in DBP degradation was observed at higher concentrations of metal ions above 1.5 mM due to the inhibition of laccase active sites. The coefficient of correlation (R2 = 0.9885) recorded in the Lineweaver bulk plot affirmed that the removal efficiencies are highly dependent on DBP concentration in the laccase-SYR system. The Gas-Chromatography Mass Spectrometry (GC-MS) analyses affirmed that the ortho-cleavage due to hydrolysis of DBP in the reaction system led to the formation of two metabolic degradation products (MBP and PA). The phytotoxicity assessment affirmed the detoxified status of DBP after treatment with significant improvement (90 and 91%) in the growth of Lens culinaris and Sorghum bicolor. This is the first report on DBP degradation in the laccase-SYR reaction system, underscoring the unique, eco-friendly, economical, and promising alternative to known conventional methods.

Effect of an environmental microplastic mixture from the Seine River and one of the main associated plasticizers, dibutylphthalate, on the sentinel species Hediste diversicolor.

The aim of this study was to explore the adverse effects of a microplastic (MP) mixture obtained from litter accumulated in the Seine River (France) compared to those of their major co-plasticizer, dibutylphthalate (DBP), on the sentinel species Hediste diversicolor. A suite of biomarkers has been investigated to study the impacts of MPs (100 mg kg-1 sediment), DBP (38 µg kg-1 sediment) on worms compared to non-exposed individuals after 4 and 21 days. The antioxidant response, immunity, neurotoxicity and energy and respiratory metabolism were investigated using biomarkers. After 21 days, worms exposed to MPs showed an increasing aerobic metabolism, an enhancement of both antioxidant and neuroimmune responses. Energy-related biomarkers demonstrated that the energy reallocated to the defence system may come from proteins. A similar impact was depicted after DBP exposure, except for neurotoxicity. Our results provide a better understanding of the ecotoxicological effects of environmental MPs and their associated-contaminants on H. diversicolor.

Combined cytotoxicity of phthalate esters on HepG2 cells: A comprehensive analysis of transcriptomics and metabolomics.

Phthalate esters (PAEs), widely used as plasticizers, may pose a potential environmental and human hazard. The aim of this study was to compare the cytotoxicity of di(2-ethylhexyl) phthalates (DEHP) and dibutyl phthalate (DBP)) after their exposure to HepG2 cells alone or in combination. HepG2 cells treated with individual/combined DEHP and DBP at a dose of 10-2 M for 24 h were selected for metabolome and transcriptome analysis. The results demonstrated that exposure to the mixtures of DEHP and DBP caused enhanced or reduced toxic effects regarding 8 pathways with 1065 downregulated genes and 643 upregulated genes, in comparison with those of single chemicals. The combined toxicity of mixture revealed both synergistic and antagonistic interactions between DEHP and DBP. Besides, combined exposure to DEHP and DBP promoted TCA cycle, pyrimidine, and purine metabolism, while an antagonistic effect on fatty acid derangement should require further investigation. To summarize, our results suggest that DEHP exposed alone or combined with DBP caused a variety of metabolic disorders, and the type of combination effects varied among metabolic pathways.

α-Galactosidase interacts with persistent organic pollutants to induce oxidative stresses in rice (Oryza sativa L.).

Persistent organic pollutants (POPs) in agricultural soil often triggered metabolic alterations and phytotoxicity in plants, ultimately threatening crop quality. Unraveling the phytotoxic mechanisms of POPs in crops is critical for evaluating their environmental risks. Herein, the molecular mechanism of POP-induced phytotoxicity in rice (Oryza sativa L.) was analyzed using metabolic profile, enzyme activity, and gene expression as linkages, including polycyclic aromatic hydrocarbons, polybrominated diphenyl ethers, polychlorinated biphenyls, and phthalate esters. Despite no observable changes in phenotypic traits (e.g., biomass and length of aboveground), the levels of reactive oxygen species (ROS) were promoted under stresses of the tested POPs, particularly 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), dibutyl phthalate (DBP), and di(2-ethylhexyl) phthalate (DEHP). Metabolomics analysis revealed that ROS contents positively correlated with metabolic perturbation levels (r = 0.83), among which the galactose metabolism was significantly inhibited when exposed to DBP, DEHP, or BDE-47. The α-Galactosidase (α-Gal) involved in galactose metabolism was targeted as the key enzyme for the phytotoxicity of DBP, DEHP, and BDE-47, which was revealed by the inhibition of saccharide levels (45.5-82.1%), the catalytic activity of α-Gal (18.5-24.3%), and the gene expression (28.5-34.5%). Molecular docking simulation suggested that the three POPs occupied the active sites of α-Gal and formed a stable protein-ligand complex, thus inhibiting the catalytic activity of α-Gal. Partial least-squares regression analysis indicated that α-Gal activity was negatively associated with hydrogen bond acceptor, rotatable bond, and topological polar surface area of POPs. The results offered novel insights into the molecular mechanisms of phytotoxicity of POPs and provided important information for evaluating the environmental risk of POPs.