【精品文档】09中英文双语外文文献翻译成品：赤红菌株DP-2单独或同步生物降解邻苯二甲酸二正丁酯和苯酚

此文档是毕业设计外文翻译成品（ 含英文原文+中文翻译），无需调整复杂的格式！下载之后直接可用，方便快捷！本文价格不贵,也就几十块钱！一辈子也就一次的事！外文标题：Individual or synchronous biodegradation of di-n-butyl phthalate and phenol by Rhodococcus ruber strain DP-2.外文作者：Z He ， C Niu ， Z Lu文献出处：Journal of Hazardous Materials , 2018 , 273 (3) :104-109(如觉得年份太老，可改为近2年，毕竟很多毕业生都这样做)英文2903单词，17889字符(字符就是印刷符)，中文4658汉字。原文：Individual or synchronous biodegradation of di-n-butyl phthalate and phenol by Rhodococcus ruber strain DP-2.h i g h l i g h t sA Rhodococcus ruber strain degraded DBP and phenol.Degradation kinetics of DBP or phenol fit modified first-order models.Degradation interaction between DBP and phenol was studied by strain DP-2.The degradation genes transcriptional were quantified by RT-qPCR.a b s t r a c tThe bacterial strain DP-2, identified as Rhodococcus ruber, is able to effectively degrade di-n-butyl phthalate (DBP) and phenol. Degradation kinetics of DBP and phenol at different initial concentrations revealed DBP and phenol degradation to fit modified first-order models. The half-life of DBP degradation ranged from 15.81 to 27.75 h and phenol degradation from 14.52 to 45.52 h under the initial concentrations of6001200 mg/L. When strain DP-2 was cultured with a mixture of DBP (800 mg/L) and phenol (700 mg/L),DBP degradation rate was found to be only slightly influenced; however, phthalic acid (PA) accumulated, and phenol degradation was clearly inhibited during synchronous degradation. Transcriptional levelsof degradation genes, phenol hydroxylase (pheu) and phthalate 3,4-dioxygenase (pht), decreased significantly more during synchronous degradation than during individual degradation. Quantitative estimation of individual or synchronous degradation kinetics is essential to manage mixed hazardous compounds through biodegradation in industrial waste disposal.IntroductionHuman industrial activities generate huge amounts of industrial waste containing different hazardous organic pollutants, and the capability of bacteria to mineralize these toxic chemicals from industrial waste environments depends substantially on the presence of other compounds. Phthalate esters (PAEs) and phenolsare two widely produced families of chemicals used to stabilizeand modify the characteristics and performance of polymers 1in industry, and currently, large amounts of these chemicals are released into environments. Di-n-butyl phthalate (DBP), one of the most commonly used PAEs, is also used in various other products, such as insecticides, packaging materials, cosmetics, coverings, clothes and insulators in electric disposals 2. Phenol, one of the basal phenols, is a major pollutant that can be employed in many industrial processes such as the production of polycarbonate resins, nylon, plastics, oil refineries, and pharmaceuticals 3. Simultaneous monitoring of phenols and PAEs has been reported in the river basin 4. Compared with the toxicity of individual chemicals, combined disposal of PAEs and phenols could induce increased lactate dehydrogenase release from Sertoli cells 5. Therefore, the additive toxic effect of two substances on cells generates pollutants that are quite recalcitrant to synchronous degradation by bacterialcells. Further quantitative estimation of individual or synchronousdegradation kinetics is essential to remove mixed hazardous com-pounds through biodegradation.Biodegradation processes of a mixture are known as interactions existing among toxic compounds 6,7. The metabolic activity of the biodegradation of two or more pollutants may involveco-metabolism 8, induction of required enzymes 9 or negative interactions 10, which depend on the different compounds, the presence of microbial species, and compound concentrations. DBP and phenol are two widely used industrial chemicals; DBP has low water solubility and high octanol/water partition coefficients, whereas phenol is water soluble and highly mobile. Different water solubility of two compounds might have an impact on the biodegradability of each compound when they co-exist. However, studies on the synchronous biodegradation of DBP andphenol are rare. Members of the Rhodococcus genus, one of the most promising groups of G+bacteria existing in the natural environment, have been isolated, identified and applied for toxic compound biodegradation. Some previous authors have reported that Rhodococcus sp.could be involved in DBP 1113 or phenol 1417 degradation individually. However, only one study found that Rhodococcus sp.had potential to mineralize DBP and phenol 18. The degradation pathway of DBP in G+bacteria involves initially converting DBPinto phthalic acid (PA), and subsequently PA is attacked by 3,4-dihydroxyphthalate forming protocatechuate (PCA) 19. Phenol degradation is mainly accompanied by the formation of catechol,which further undergoes cleavage in the meta-position or ortho-position of the cyclobenzene 20.In this study, a Rhodococcus ruber strain designated as DP-2 was isolated from activated sludge through enrichment under DBP pres-sure. DP-2 was able to utilize DBP or phenol as the sole carbon and energy source with high degradation activity. This study aimed to investigate synchronous effects, detect intermediates, and quantify catabolic gene expression levels during the process of individual orsynchronous DBP or phenol degradation.1. Materials and methods1.1. Chemicals and cultivation medium1.2. Isolation and identification of the strain DP-21.3. Biodegradation of DBP and phenol by strain DP-21.4. Biodegradation interaction between phenol and DBP by thestrain DP-21.5. RT-qPCR analysis of biodegradation gene expression1.6. Analytical procedures1.7. Kinetics and statistical analysis2. Results and discussion3.1. Isolation and characterization of strain DP-2 After enrichment and selection with 300 mg/L DBP, the most efficient strain isolated from activated sludge of a sewage plant was selected and designated as DP-2. Strain DP-2 colonies were red, and the morphology of strain DP-2 was G+, rod-shaped and motile. For the purpose of identification of strain DP-2, its 16S rRNA gene was amplified for sequencing. Based on comparison with the GenBankand Ribosomal Database Project databases, the 16S rRNA sequence exhibited a high level of 99.5% identity with Rhodococcus ruber and was deposited with the accession number KC207080.A Rhodococcus sp. was often found being capable of degrading a kind of similar compounds 26,27. Strain DP-2 was also observed to utilize phenol as the sole carbon and energy source for growth. Although DBP and phenol are two common industrial aromatic compounds, only Rhodococcus sp. L4 has yet been reported to have potential to degrade both DBP and phenol 18. However, there was no literature about synchronous degradation effects existing between DBP and phenol.3.2. Effects of initial concentrations on DBP or phenol degradation by strain DP-2Before this experiment, it was found that the permissible limits of DBP and phenol supporting for strain DP-2 growth were1500 mg/L and 1300 mg/L in MM, respectively. Hence, biodegradation of DBP or phenol by Rhodococcus ruber strain DP-2 were conducted under different initial concentrations ranging 600, 800,1000, and 1200 mg/L. As shown in Fig. 1a, rapid degradation was observed at the beginning of incubation during the DBP degradation process. Strain DP-2 completely degraded DBP with initial concentration of 600, 800, 1000 and 1200 mg/L within 42, 48, 54 and 60 h, respectively. There are other reports describing degradation of DBPby bacterial strains. In one such report by Fang et al. 28, about80% of DBP was degraded after 60 h by Enterobacter sp. T5 when the initial concentration of DBP was 1000 mg/L, and all of reported Rhodococcus strains exhibited high degradation efficiency under1000 mg/L DBP 11,13,18. The degradation rates were evidently depended on the initial concentrations. Kinetics model analyses ofthe curves were found that these curves were fitted for modified first-order models (Eq. 1 presented in Table 2). When the initial DBP concentration was 600, 800, 1000 or 1200 mg/L, the biodegradation half-life of DBP was 15.81 h (R2= 0.9669), 17.56 h (R2= 0.9873),26.53 h (R2= 0.9761), 27.75 h (R2= 0.9753) respectively. There were also other studies describing first-order kinetic models fitted for DBP degradation curves 28,29. In addition, the Gompertz model has also been reportedly used to estimate the degradation curve of DBP 25, and the lag phases usually exist in the Gompertz model degradation process due to sigmoidal curves. In this study, no apparent lag phase for DBP degradation indicated that strain DP-2was able to adapt quickly to the DBP contaminated environment.In case of phenol degradation by strain DP-2, the effect of initial concentrations of phenol on degradation rates with time are shown in Fig. 1b. The results showed that no phenol could be detected at 24 or 36 h when the initial phenol concentration was600 or 800 mg/L. However, when the initial phenol concentration was 1000 or 1200 mg/L, approximately 90% of the phenol was degraded by strain DP-2 after 60 h of inoculation. Strain DP-2 growth was inhibited at 1500 mg/L in MM (data not given out).Studies on phenol degradation by other Rhodococcus species indicates Rhodococcus species exhibited high capability of degrading phenol at high phenol concentration (1000 mg/L) 15,17. Phenoldegradation kinetics under various initial concentrations also fit modified first-order models well, but a brief lag phase exists in the degradation curves. However, Adav et al. 30 have reported an Acinetobacter strain that had 520 h lag phase under initial phenol concentrations from 500 mg/L to 1000 mg/L. In addition ,a fungi, Paecilomyces variotii JH6, had an approximately 40 h lagphase when degrading low concentrations of phenol ranged from100 to 400 mg/L 31. The above results highlighted that the strainDP-2 might have the potential to be used in the bioremediation of phenol and DBP contaminated environments.3.3. Biodegradation interaction between DBP and phenolThe capability of a bacterial strain to degrade toxic compounds from industrial wastes depends on the presence of not only easily degradable compounds such as sugars but also with toxic chemicals32. Interaction also existed during synchronous degradation of phenol and DBP. The results showed that the DBP degradation rate was not significantly influenced by phenol in mixture; however, the phenol degradation efficiency was inhibited (Fig. 2a, b). Inter-action existing among mixture reflected in not only degradation rates of toxic compounds but also concentrations of intermediates variation during synchronous degradation process. Intermediates of phenol or DBP, such as catechol and PA, were also monitored(Fig. 2c, d). PA concentration was fluctuant during the individual DBP degradation process; however, its concentration was on the rise and higher during the synchronous degradation than that in the individual cultivation. Catechol concentration peaked at 30 h during the individual phenol degradation process and at 48 h during the mixture degradation process. The interaction among co-contaminants on the bacterial degradation efficiency was summed up through three models: enhancement 33, inhibition 34 and cometabolism 35. In this study, the results might be that co-cultivation of phenol and DBP exhibited preferential degradation of DBP by strain DP-2in mixture. In the mixtures of three nitrogen heterocyclic com-pounds, quinolone, which is the easiest to be degraded, was not inhibited by others, and pyridine and carbazole degradation were also both inhibited in mixtures 36. A bacterial strain that preferentially degrades one toxic chemical over another structurally similar compound may be due to different degradation pathways involving different catabolic genes and intermediates 6.3.4. Catabolic gene expression during individual or synchronousdegradation processThe presence of various catabolic genes determines the biodegradation potential of bacteria. In this study, two sets of degenerated primers (Table 1) were used to amplify the relevant genes responsible for key steps of the degradation of DBP and phenol. Phthalate dioxygenase is a well characterized enzyme which plays a key role in the biodegradation of phthalate esters in bacteria37. In strain DP-2, a fragment of 1105 bp of the phthalate dioxyge-nase gene (pht) was also cloned. The sequence analysis showed that the obtained fragment was most homologous with the nucleotide sequences of phthalate 3,4-dioxygenase which hydroxylated the phthalate ring at positions 3 and 4 in Gram-positive bacteria. Phenolhydroxylase catalyzes the conversion of phenol into catechol, therate-limiting step in the phenol degradation pathway in bacteria. The PCR product of phenol hydroxylase gene (pheu) was 810 bp-lengths in strain DP-2.Catabolic genes expression could be correlated with degradation rate during the toxic compound degradation process. So far most of studies aiming to describe the correlation between catabolic genes expression and degradation rate only focused on individual pollutant degradation process 38,39. It also has been reported that pht expression was induced by phthalic acid during DBP degradation process 25. To the best of our knowledge, this study is the first to quantify catabolic genes expression for the purpose of studying interaction existing in mixture. It was ofgreat importance to study catabolic genes being induced by one compound and being influenced by the other toxic compound in mixture, which would be helpful for understanding the mixture co-metabolic process. As shown in Fig. 3a, transcriptional level of pheu was decreased during synchronous degradation process compared with individual degradation process, and was almost not induced during individual DBP degradation process. Enhanced pheu expression leaded to catechol accumulation and increasing degradationrate during both synchronous and individual degradation process(Figs. 2b, d, and 3a). Different from pheu, the transcriptional level of pht was almost not induced during synchronous degradation process (Fig. 3b), and kept relatively stable within 1836 h during individual DBP degradation process. The above results indicated that phenol hydroxylation was delayed and phthalic acid trans-formation of DBP degradation pathway was completely inhibitedduring the synchronous degradation process.3. ConclusionsThis study demonstrated that the strain DP-2 was able to degrade the aromatic compounds phenol and DBP. 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