Degradation Of Dibutyl Phthalate Research Articles

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.

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.

Efficient removal of endocrine disruptors using nano zero-valent iron loaded organo-attapulgite: Mechanism and factors

Endocrine-disrupting pollutants have become a major problem in aquatic environments. Advanced oxidation processes are recognized as promising technologies for treating endocrine disruptor-contaminated water. Herein, a novel nanoscale zero-valent iron loaded organo-attapulgite (NZVI@OATP) was employed as a catalyst to activate persulfate (PDS) for phenanthrene (PHE) and dibutyl phthalate (DBP) degradation. NZVI@OATP with a NZVI:OATP mole ratio of 1:1 (CTAB:ATP = 1:200) exhibited 100 % PHE and 84 % DBP degradation within 30 min, and chloride was found to have a positive effect on their degradation. Radical scavenger and electron paramagnetic resonance studies revealed that the contribution of the active species follows the order of O2- ≈ 1O2>SO4- ≫ OH. The optimal degradation pathways were proposed based on the liquid chromatography-mass spectrometry and density functional theory and the possible degradation paths of PHE and DBP, including the 9,10-phenanthraquinone and phthalic acid pathways, respectively, were proposed. The toxicity estimation software tool showed that the toxicities of PHE and DBP were reduced after degradation. Moreover, 50 % PHE degradation could be achieved after five cycles, demonstrating that NZVI@OATP is a promising catalyst for endocrine disruptor treatment with PDS.

Unraveling the crucial role of Mo2N from Fe/Mo bimetal MOF-derived catalyst in initiating Fe3+/Fe2+ redox cycle to activate peroxymonosulfate for dibutyl phthalate degradation

Phthalic acid esters (PAEs) pose serious health risks to humans and are difficult to remove by conventional sewage treatment processes. Herein, Fe2Mo3O8/MoO2/Mo2N composite (FMON) derived from bimetallic organic framework was used to activate peroxymonosulfate (PMS) for dibutyl phthalate (DBP) degradation. FMON exhibited an excellent catalytic effect with DBP removal efficiency of 92.4 % within 60 min. Mo2N showed a superior ability in promoting Fe3+/Fe2+ redox cycle. The reduction efficiencies of Fe3+ by Mo2N/MoO2 composite and MoO2 were 67 %–94 % and 11 %–23 %, respectively, in the homogeneous comparative experiment. Moreover, the ratio of Fe2+/Fe3+ in FMON increased significantly after the catalytic reaction. Fe element doping also enhanced the reuse stability and reduced the metal ion leaching of the catalyst. The degradation of DBP was mediated by a variety of reactive species, of which SO4−, OH and O2− were dominant. Fe element, Mo element and O vacancies were confirmed to exert significant contributions as active sites in the catalytic process. Three degradation pathways of DBP were obtained by DFT calculation and HPLC-MS analysis. And the toxicity of DBP degradation products was significantly reduced based on the assessment result of Toxicity Estimation Software Tool (T.E.S.T.). This study explored a novel Fe/Mo bimetallic catalyst with friendly Fe3+/Fe2+ cycling for environmental catalysis and provided new ideas for the treatment of PAEs wastewater.

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.

Uptake, accumulation, and degradation of dibutyl phthalate by three wetland plants.

The uptake and degradation mechanisms of dibutyl phthalate (DBP) by three wetland plants, namely Lythrum salicaria, Thalia dealbata, and Canna indica, were studied using hydroponics. The results revealed that exposure to DBP at 0.5 mg/L had no significant effect on the growth of L. salicaria and C. indica but inhibited the growth of T. dealbata. After 28 days, DBP concentrations in the roots of L. salicaria, T. dealbata, and C. indica were 8.74, 5.67, and 5.46 mg/kg, respectively, compared to 2.03-3.95 mg/kg in stems and leaves. Mono-n-butyl phthalate concentrations in L. salicaria tissues were significantly higher than those in the other two plants at 23.1, 15.0, and 13.6 mg/kg in roots, stems, and leaves, respectively. The roots of L. salicaria also had the highest concentration of phthalic acid, reaching 2.45 mg/kg. Carboxylesterase, polyphenol oxidase, and superoxide dismutase may be the primary enzymes involved in DBP degradation in wetland plants. The activities of these three enzymes exhibited significant changes in plant tissues. The findings suggest L. salicaria as a potent plant for phytoremediation and use in constructed wetlands for the treatment of DBP-contaminated wastewater.

Dibutyl Phthalate Adsorbed on Multiwalled Carbon Nanotubes Causes Fetal Developmental Toxicity in Balb/C Mice.

This study investigated whether using multiwalled carbon nanotubes (MWCNTs) as a carrier for dibutyl phthalate (DBP) could delay the degradation rate of DBP in mice and increase its estrogen-like interference effect. Pregnant Balb/C mice were divided into four groups and exposed to different treatments via tail-vein injection every 3 days until gestational day 20. The female and male mice were then sacrificed for toxicological study. The results showed that the combination of MWCNTs and DBP resulted in a higher fetal mortality rate than if the mice were exposed to MWCNTs or DBP alone. H&E staining showed that the estrous period of the exposed mice was delayed, the development of oocytes was blocked in the combination group, the number of spermatogenic cells decreased, and the quality of sperm decreased. Our experiment showed that the expression levels of the genes involved in sex hormone synthesis in the testis and ovaries were significantly increased after combined treatment compared with the MWCNT group (p < 0.01). The study suggests that DBP degradation is delayed when absorbed on MWCNTs, which increases its estrogen-like interference and interferes with fetal development, ultimately leading to increased fetal mortality.

Immobilization of esterase from Bacillus subtilis on Halloysite nanotubes and applications on dibutyl phthalate degradation

Immobilization of esterase from Bacillus subtilis on Halloysite nanotubes and applications on dibutyl phthalate degradation

Degradation of dibutyl phthalate and diethyl phthalate by indigenous isolate Bacillus sp. MY156

Dibutyl phthalate (DBP) and diethyl phthalate (DEP) are among the most extensively utilized plasticizers and widely exist in the environment causing adverse effect on human health. Previous studies on these phthalic acid esters (PAEs) biodegradation mainly involved individual substrates. However, these contaminants are more possible existed in mixtures. This work explored the biodegradation of DBP and DEP and their interactions using the indigenous isolate Bacillus sp. MY156. The results demonstrate DBP could be completely degraded by strain MY156 with high efficiency, while DEP showed relatively lower removal efficiency (72%) in 120 h. The binary substrate removal results revealed the coexistence of DBP and DEP had no significant influence on the degradation of each under the optimal pH and temperature. Nevertheless, slight retardation of the removal efficiency for DEP noticed as co-existed with DBP demonstrated their removal was possibly affected through the substrate competition. The dehydrogenase activity assay illustrated the behaviors of dehydrogenases caused by long-side chains PAEs were higher than PAEs with shorter alkyl chains. The isolate Bacillus sp. MY156 showed a positive utilization potentiality for bioremediation of PAEs-polluted environment.

One-step synthesis of Bi2O2CO3/Bi2S3 S-scheme heterostructure with enhanced photoactivity towards dibutyl phthalate degradation under visible light

Bi2O2CO3/Bi2S3 heterojunction was prepared by one-step hydrothermal method, where Bi(NO3)3 was employed as Bi source, Na2S was used as a sulfur source, and CO(NH2)2 was adopted as C source. The load of Bi2S3 was adjusted by changing the content of Na2S. The prepared Bi2O2CO3/Bi2S3 illustrated strong photocatalytic activity towards dibutyl phthalate (DBP) degradation. The degradation rate was 73.6% under the irradiation of visible light for 3 h, which were 3.5 and 1.87 times for Bi2O2CO3 and Bi2S3, respectively. In addition, the mechanism for the enhanced photoactivity was investigated. After combined with Bi2S3, the formed heterojunction structure inhibited the recombination of photogenerated electron-hole pair, improved the visible light adsorption, and accelerated the migration rate of the photogenerated electron. As a result, analysis of the radical formation and the energy band structure revealed that Bi2O2CO3/Bi2S3 was consistent with the S-scheme heterojunction model. The S-scheme heterojunction allowed the Bi2O2CO3/Bi2S3 to possess high photocatalytic activity. The prepared photocatalyst presented acceptable cycle application stability. This work not only develops a facile one-step synthesis technique for Bi2O2CO3/Bi2S3, and also provides a good platform for the degradation of DBP.

Fenton-like photocatalyzed degradation of dibutyl phthalate with goethite and carboxylic acids

Detailed investigation of photocatalyzed degradation of dibutyl phthalate (DBP), an endocrine disrupter, in the presence of α-FeOOH (goethite) and different carboxylic acids is the focus of this study. To get a better insight into the efficiency of the degradation, the influence of different parameters, such as concentration of total Fe and Fe(II), dissolved oxygen, DBP concentration, pH and salinity is investigated. The reaction mechanism consists of several interrelationship steps. The first step is the chemical reaction of carboxylic acid groups of the organic acids with hydroxyl groups of the α-FeOOH and a charge transfer upon illumination generating Fe(II). The second step is the release of Fe(II) into the solution followed by H2O2 oxidation to form highly photoactive hydroxyl complex of iron(III) and ˙OH. Simultaneously, the superoxide radical O2˙− and hydroperoxyl radical is formed in acidic solutions in presence of carboxylic acids as well. This mechanism explains the genesis of different reactive species oxidizing DBP. From the variety of the studied carboxylic acids (oxalic, citric, salicylic, pyruvic, maleic, and fumaric), oxalic acid is the best Fe-ligand for the photoreductive dissolution of goethite. Concentrations of the total amount of Fe and its dissociated forms Fe(II) as well as oxygen and hydroxyl radicals play a fundamental role in efficiency of DBP degradation. The photodegradation of DBP with goethite and the use of suitable carboxylic acids under optimized reaction conditions could be an efficient process for decontamination of polluted waters.

Fluorescent labeling and tracing of immobilized efficient degrading bacterium DNB-S1 and its remediation efficiency of DBP contaminated soil

Dibutyl phthalate (DBP) is an organic pollutant frequently detected in soil, and is a reproductive poison that harms animals both before and after birth and has mutagenic, teratogenic, and carcinogenic effects. DBP removal from farmland has been the subject of extensive research in recent years. Efficient DBP degrading bacterial strains were screened in the laboratory. GFP (Green fluorescent protein) labeled degradation strain GFP-DNB-S1 was analyzed for its activity and dynamics. Using sodium alginate (SA) and nano-hydroxyapatite (n-HAP) as carrier materials and CaCl2 as a cross-linking agent, the immobilized microbial agent n-HAP/SA + DNB-S1 was prepared by embedding cross-linking immobilization technology to study the remediation effect of DBP contaminated soil. The best formation effect of immobilized materials (n-HAP/SA) was found when the SA to n-HAP ratio was 3:2. When compared to single SA immobilized bacteria, n-HAP/SA immobilized bacteria improved the surface roughness and porosity of the microspheres. After 70 days, LED light revealed that the immobilized bacteria's GFP green fluorescent protein expression was stable. At 70 days, the initial DBP concentration of 500 mg ∙ L−1 degraded at a rate of 69.9%. The degrading bacteria had no effect on DBP degradation before and after being labeled with GFP. The n-HAP/SA immobilized bacteria offered a better living environment for microorganisms due to their rougher surface and a greater number of pores. This protected the microorganisms and increased the efficiency of DBP degradation. When the concentration of DBP in contaminated soil was set to 20 mg ∙ kg−1 and the n-HAP/SA + DNB-S1 immobilized bacterial agent was applied to the soil, the rate of DBP degradation was determined to be 93.34%. The degradation process followed First-order degradation kinetics, which improved the physical and chemical properties of the soil as well as its fertility.

Бактерии-деструкторы дибутилфталата, выделенные из ризосферы мятлика лугового (Poa pratensis L.)

The ability of three bacterial strains of the class Actinomycetes, isolated from the rhizosphere of bluegrass (Poa pratensis L.) plants growing in the industrial development area of the Verkhnekamsk salt deposit (Perm krai), to grow on dibutyl phthalate (DBP) as the only source of carbon and energy was studied. Based on 16S rRNA gene analysis, it was shown that the strain Rh7bel showed similarity at 100% level with Rhodococcus wratislaviensis NBRC 100605T, and strains NKDBFbel and NKDBFgelt are phylogenetically close to two type strains of the species Pseudarthrobacter oxydans and Pseudarthrobacter polychromogenes (99.83% similarity). DBP-degrading strains are characterized by efficient growth on the key metabolite of DBP degradation, ortho-phthalic acid, and utilization of this metabolite. The strain Rhodococcus sp. Rh7bel demonstrated the highest rates of DBP utilization: the maximum specific substrate consumption rate was 0.018±0.002 h-1, substrate utili-zation was 70.7% in 72 hours (initial DBP concentration 0.2 g/L). Thus, rhizosphere DBP-degrading strains Rhodococcus sp. Rh7bel, Pseudarthrobacter spp. NKDBFbel and NKDBFgelt are promising for further study and development of technology for phytoremediation of soils contaminated with phthalates.

Degradation of dibutyl phthalate by ozonation in the ultrasonic cavitation-rotational flow interaction coupled-field: performance and mechanism.

Dibutyl phthalate (DBP) is present in hydraulic fracturing flowback and produced water. Degradation of DBP in aqueous by means of ozonation in ultrasonic cavitation-rotational flow interaction coupled-field (UC-RF coupled-field) was studied. The effect of ozone dosage, ozone intake flow, operating temperature, initial pH, DBP initial concentration, liquid flow rate, and ultrasonic power on the DBP removal was investigated. Results indicated that the DBP degradation rate was strongly influenced by the liquid flow rate and the ultrasonic power over the range investigated. HCO3- and Cl- revealed an inhibitory effect on the DBP removal. SO42- seemed to have no effect on DBP removal. The ozone utilization efficiencies in the UC-RF coupled-field were 2.77 and 1.13 times higher than those in the conventional microporous aeration (CMA) and rotating-flow microbubble aeration (RFMA), respectively. The DBP degradation rate was diminished in the presence of tert-butyl alcohol. Cavitation bubbles are considered as innumerable microreactors. Degradation of DBP by direct ozonation, hydroxyl radical (·OH) oxidation, high pressure, and high-temperature pyrolysis was demonstrated. Finally, a possible degradation pathway of DBP is obtained on the basis of the main reaction intermediates.

Continuous treatment of diethyl hexyl and dibutyl phthalates by fixed-bed reactor: Comparison of two esterase bionanocomposites

The removal of Diethyl hexyl phthalate (DEHP) and Dibutyl phthalate (DBP) is of great importance due to their potential adverse effects on the environment and human health. In this study, two bionanocomposites prepared by immobilization of Bacillus subtilis esterase by crosslinking to halloysite and supported in chitosan and alginate beads were studied and proposed as a green approach. The esterase immobilization was confirmed by physical–chemical characterization. Bionanocomposite using chitosan showed the best degradation levels in batch tests attaining complete degradation of DBP and around 90% of DEHP. To determine the operational stability and efficiency of the system, two fixed bed reactors filled with both bionanocomposites were carried out operating in continuous mode. Chitosan based bionanocomposite showed the best performance being able to completely remove DBP and more than 85% of DEHP at the different flowrates. These results proved the potential of these synthesized bionanocomposites to effectively remove Phthalic Acid Esters.

Biodegradation of Dibutyl Phthalate by the New Strain Acinetobacter baumannii DP-2.

Optimizing the culture conditions of DBP degradation by bacteria and investigating its biodegradation pathways have a great importance to develop effective PAEs pollution control strategies. In this study, we investigated the cultivation condition optimization, degradation kinetics, and degradation pathways of a newly isolated dibutyl phthalate (DBP) degradation strain, which was isolated from activated sludge and identified as Acinetobacter baumannii DP-2 via morphological observation, biochemical identification, and 16S rDNA sequence analysis. The degradation conditions were optimized based on the results of single-factor experiments and response surface optimization experiments. The DBP degradation rate of Acinetobacter baumannii DP-2 reached up to 85.86% when the inoculation amount was 17.14%, the DBP concentration was 9.81 mg·L−1 and the NaCl concentration was 5 g·L−1. The GC-MS analysis results indicated that the intermediate metabolites of Acinetobacter baumannii DP-2 mainly consisted of DMP, MBP, PA, and benzoic acid derivatives, which confirmed the degradation pathway from DBP to PA under aerobic pathway and then to BA under anaerobic pathway. In summary, Acinetobacter baumannii DP-2 shows great potential for the degradation of DBP in contaminated soils.

Development of Ag/Ag2O/ZnO photocatalyst and their photocatalytic activity towards dibutyl phthalate decomposition in water

ABSTRACT The photocatalyst Ag/Ag2O-modified ZnO, fabricated by a simple one-step calcination method, was applied into the degradation of organic pollutant dibutyl phthalate (DBP). Ag/ZnO and Ag2O/ZnO were prepared as a reference comparison. The prepared catalysts were evaluated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), BET surface area measurement, and photoluminescence spectra (PL) and UV–Vis diffuse reflectance spectroscopy (DRS) and electrochemical measurements. After the irradiation with ultraviolet light (352 nm), the solution was sampled and subjected to HPLC to evaluate the degradation efficiency of DBP. Ag/Ag2O/ZnO showed the best results with the excellent degradation of DBP. Ag/Ag2O/ZnO was four times more efficient, relative to zinc oxide alone. According to photocatalyst characterization, the total pore volume of photocatalyst was improved by loading Ag and Ag2O, suggesting an increase in the active sites. Also, the efficient electron transfer of Ag/Ag2O/ZnO was mainly responsible for the enhanced activity. The reaction mechanism for Ag/Ag2O/ZnO was determined to become a Z-scheme. From the radical scavenger tests, the main active species was identified as superoxide radicals. The stability of Ag/Ag2O/ZnO could be confirmed after five cycling reutilization. It was found from the radical scavenger test that •O2 – play an important role as the main reactive species in the photocatalytic degradation of DBP. Consequently, Ag/Ag2O/ZnO with a simple fabrication method seems to become one of the powerful photocatalyst for the photocatalytic degradation of organic pollutant in water. Implications: This study discusses the usefulness of Ag/Ag2O/ZnO composites. This photocatalyst could be an approach to solve the environmental pollution caused by organic pollutants, which is a growing problem all over the world. In addition, the highly efficient photocatalyst Ag/Ag2O/ZnO is an inexpensive and reusable catalyst with great practical potential. Furthermore, to the best of our knowledge, there are very few reports that have examined the combination of Ag, Ag2O and ZnO. In addition, the photocatalytic mechanism has not been understood. Here, we introduce Ag into Ag2O/ZnO to improve the photocatalytic performance and photostability, enhance the activity, and elucidate the mechanism of Ag/Ag2O/ZnO.

Reproductive toxicity of dibutyl phthalate adsorbed on carbon nanotubes in male Balb/C mice

Dibutyl phthalate (DBP) is an environmental hormone disrupter. This study was designed to investigate whether DBP adsorbed in multi-walled carbon nanotubes (MWCNTs) can easily cross the blood-testis barrier and slow down the degradation of DBP in male mice, thereby prolonging the interference effect of DBP. The results showed that: in male Balb/C mice, the sperm density of the MWCNTs group and the DBP plus MWCNTs group decreased significantly (p < 0.05); and the sperm deformity rate increased significantly (p < 0.05). Testicular tissue sections from the combined exposure group showed that most of the seminiferous tubules were atrophied, there were more large gaps between the cells in the tubules, and the number of mature-sperm decreased. The reactive oxygen species (ROS) levels increased significantly in the combined exposure group (p < 0.01). Proteomics results showed that there were 231 differentially expressed proteins in the combined exposure group compared with the MWCNTs only group, and 69 differentially expressed proteins compared with the DBP group. GO enrichment analysis showed that the differentially expressed proteins mainly include: 60 s acid ribosomal protein P1; nuclear autoantigen sperm protein; centromere protein V; and other proteins related to cell division. These results indicate that MWCNTs with adsorbed DBP can increase oxidative damage in the testis of male mice, interfere with DNA replication and cell division in testicular tissue cells, induce cell apoptosis, and destroy the normal spermatogenic function of the testis.

Isolation of Dibutyl Phthalate-Degrading Bacteria and Its Coculture with Citrobacter freundii CD-9 to Degrade Fenvalerate.

Continued fenvalerate use has caused serious environmental pollution and requires large-scale remediation. Dibutyl phthalate (DBP) was discovered in fenvalerate metabolites degraded by Citrobacter freundii CD-9. Coculturing is an effective method for bioremediation, but few studies have analyzed the degradation pathways and potential mechanisms of cocultures. Here, a DBP-degrading strain (BDBP 071) was isolated from soil contaminated with pyrethroid pesticides (PPs) and identified as Stenotrophomonas acidaminiphila. The optimum conditions for DBP degradation were determined by response surface methodology (RSM) analysis to be 30.9 mg/l DBP concentration, pH 7.5, at a culture temperature of 37.2°C. Under the optimized conditions, approximately 88% of DBP was degraded within 48 h and five metabolites were detected. Coculturing C. freundii CD-9 and S. acidaminiphila BDBP 071 promoted fenvalerate degradation. When CD-9 was cultured for 16 h before adding BDBP 071, the strain inoculation ratio was 5:5 (v/v), fenvalerate concentration was 75.0 mg/l, fenvalerate was degraded to 84.37 ± 1.25%, and DBP level was reduced by 5.21 mg/l. In addition, 12 fenvalerate metabolites were identified and a pathway for fenvalerate degradation by the cocultured strains was proposed. These results provide theoretical data for further exploration of the mechanisms used by this coculture system to degrade fenvalerate and DBP, and also offer a promising method for effective bioremediation of PPs and their related metabolites in polluted environments.

Process intensification of the ozone-liquid mass transfer in ultrasonic cavitation-rotational flow interaction coupled-field: Optimization and application

A study on the intensification of ozone mass transfer in rotational flow field and UC-RF coupled-field was conducted. Two important operational parameters namely liquid flow rate and ultrasonic power, were optimized with regard to the ozone mass transfer efficiency. Results showed that the mass transfer coefficient (KLa) increased with liquid flow rate (up to 14 L min−1) and ultrasonic power (up to 1000 W). The maximum KLa value (1.0258 min−1) was obtained with the UC-RF coupled-field. Moreover, the reinforcement of mass transfer efficiency was promoted by the rotational flow field and UC-RF coupled-field due to the increase in the ozone-liquid contact area, intensification of turbulence, acceleration of interface renewal, and extension of residence time. Ozone microbubbles rose in the reactor in a spiral manner. In addition, the microbubbles produced in the rotational flow field served as cavitation nucleus that helped to generate the cavitation effect. The effective degradation of di-butyl phthalate (DBP) confirmed that its removal was improved by the ozone-liquid mass transfer and the promotion of hydroxyl radicals (·OH) production. The synergistic effect of DBP degradation via ultrasound-enhanced ozonation was significant.