Biodegradation of p-nitrophenol by engineered strain.
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ABSTRACT:
SUBMITTER: Xu J
PROVIDER: S-EPMC8408293 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Cupriavidus sp. strain CNP-8 isolated from a pesticide-contaminated soil was able to utilize 2-chloro-4-nitrophenol (2C4NP) as a sole source of carbon, nitrogen and energy, together with the release of nitrite and chloride ions. It could degrade 2C4NP at temperatures from 20 to 40 °C and at pH values from 5 to 10, and degrade 2C4NP as high as 1.6 mM. Kinetics assay showed that biodegradation of 2C4NP followed Haldane substrate inhibition model, with the maximum specific growth rate (?max) of 0.148/h, half saturation constant (Ks) of 0.022 mM and substrate inhibition constant (Ki) of 0.72 mM. Strain CNP-8 was proposed to degrade 2C4NP with hydroxyquinol (1,2,4-benzenetriol, BT) as the ring-cleavage substrate. The 2C4NP catabolic pathway in strain CNP-8 is significant from those reported in other Gram-negative 2C4NP utilizers. Enzymatic assay indicated that the monooxygenase initiating 2C4NP catabolism had different substrates specificity compared with previously reported 2C4NP monooxygenations. Capillary assays showed that strain CNP-8 exhibited metabolism-dependent chemotactic response toward 2C4NP at the optimum concentration of 0.5 mM with a maximum chemotaxis index of 37.5. Furthermore, microcosm studies demonstrated that strain CNP-8, especially the pre-induced cells, could remove 2C4NP rapidly from the 2C4NP-contaminated soil. Considering its adaptability to pH and temperature fluctuations and great degradation efficiency against 2C4NP, strain CNP-8 could be a promising candidate for the bioremediation of 2C4NP-contaminated sites.
| S-EPMC5861257 | biostudies-literature
Project description:para-Nitrophenol (PNP), 3-methyl-4-nitrophenol (3M4NP), and 2-chloro-4-nitrophenol (2C4NP) are highly toxic compounds that have caused serious environmental issues. We inoculated an artificially contaminated soil with Burkholderia sp. strain SJ98, which has the ability to degrade PNP, 3M4NP, and 2C4NP, and quantified bioremediation. There was accelerated degradation of all nitrophenols in inoculated treatments compared to the un-inoculated treatments. The indigenous bacteria were able to degrade PNP, but not 3M4NP or 2C4NP. Real-time PCR targeting the catabolic gene pnpA showed that levels of strain SJ98 remained stable over the incubation period. High-throughput sequencing revealed that both contamination and bioaugmentation influenced the bacterial community structure. Bioaugmentation seemed to protect Kineosporia, Nitrososphaera, and Schlesneria from nitrophenol inhibition, as well as led to a sharp increase in the abundance of Nonomuraea, Kribbella, and Saccharopolyspora. There was a significant increase in the relative abundances of Thermasporomyces, Actinomadura, and Streptomyces in both contaminated and bioaugmented treatments; this indicated that these bacteria are likely directly related to nitrophenol degradation. To our knowledge, this is the first report of the simultaneous removal of PNP, 3M4NP, and 2C4NP using bioaugmentation. This study provides valuable insights into the bioremediation of soils contaminated with nitrophenols.
| S-EPMC5519733 | biostudies-literature
Project description:Burkholderia sp. strain SJ98 (DSM 23195) utilizes 2-chloro-4-nitrophenol (2C4NP) or para-nitrophenol (PNP) as a sole source of carbon and energy. Here, by genetic and biochemical analyses, a 2C4NP catabolic pathway different from those of all other 2C4NP utilizers was identified with chloro-1,4-benzoquinone (CBQ) as an intermediate. Reverse transcription-PCR analysis showed that all of the pnp genes in the pnpABA1CDEF cluster were located in a single operon, which is significantly different from the genetic organization of all other previously reported PNP degradation gene clusters, in which the structural genes were located in three different operons. All of the Pnp proteins were purified to homogeneity as His-tagged proteins. PnpA, a PNP 4-monooxygenase, was found to be able to catalyze the monooxygenation of 2C4NP to CBQ. PnpB, a 1,4-benzoquinone reductase, has the ability to catalyze the reduction of CBQ to chlorohydroquinone. Moreover, PnpB is also able to enhance PnpA activity in vitro in the conversion of 2C4NP to CBQ. Genetic analyses indicated that pnpA plays an essential role in the degradation of both 2C4NP and PNP by gene knockout and complementation. In addition to being responsible for the lower pathway of PNP catabolism, PnpCD, PnpE, and PnpF were also found to be likely involved in that of 2C4NP catabolism. These results indicated that the catabolism of 2C4NP and that of PNP share the same gene cluster in strain SJ98. These findings fill a gap in our understanding of the microbial degradation of 2C4NP at the molecular and biochemical levels.
| S-EPMC4178678 | biostudies-literature
Project description:4-Nitrophenol (4-NP) is a toxic product of the hydrolysis of organophosphorus pesticides such as parathion in soil. Rhodococcus sp. strain PN1 degrades 4-NP via 4-nitrocatechol (4-NC) for use as the sole carbon, nitrogen, and energy source. A 5-kb EcoRI DNA fragment previously cloned from PN1 contained a gene cluster (nphRA1A2) involved in 4-NP oxidation. From sequence analysis, this gene cluster is expected to encode an AraC/XylS family regulatory protein (NphR) and a two-component 4-NP hydroxylase (NphA1 and NphA2). A transcriptional assay in a Rhodococcus strain revealed that the transcription of nphA1 is induced by only 4-NP (of several phenolic compounds tested) in the presence of nphR, which is constitutively expressed. Disruption of nphR abolished transcriptional activity, suggesting that nphR encodes a positive regulatory protein. The two proteins of the 4-NP hydroxylase, NphA1 and NphA2, were independently expressed in Escherichia coli and purified by ion-exchange chromatography or affinity chromatography. The purified NphA2 reduced flavin adenine dinucleotide (FAD) with the concomitant oxidation of NADH, while the purified NphA1 oxidized 4-NP into 4-NC almost quantitatively in the presence of FAD, NADH, and NphA2. This functional analysis, in addition to the sequence analysis, revealed that this enzyme system belongs to the two-component flavin-diffusible monooxygenase family. The 4-NP hydroxylase showed comparable oxidation activities for phenol and 4-chlorophenol to that for 4-NP and weaker activities for 3-NP and 4-NC.
| S-EPMC2576653 | biostudies-literature
Project description:A bacterium designated Pseudonocardia sp. strain ENV478 was isolated by enrichment culturing on tetrahydrofuran (THF) and was screened to determine its ability to degrade a range of ether pollutants. After growth on THF, strain ENV478 degraded THF (63 mg/h/g total suspended solids [TSS]), 1,4-dioxane (21 mg/h/g TSS), 1,3-dioxolane (19 mg/h/g TSS), bis-2-chloroethylether (BCEE) (12 mg/h/g TSS), and methyl tert-butyl ether (MTBE) (9.1 mg/h/g TSS). Although the highest rates of 1,4-dioxane degradation occurred after growth on THF, strain ENV478 also degraded 1,4-dioxane after growth on sucrose, lactate, yeast extract, 2-propanol, and propane, indicating that there was some level of constitutive degradative activity. The BCEE degradation rates were about threefold higher after growth on propane (32 mg/h/g TSS) than after growth on THF, and MTBE degradation resulted in accumulation of tert-butyl alcohol. Degradation of 1,4-dioxane resulted in accumulation of 2-hydroxyethoxyacetic acid (2HEAA). Despite its inability to grow on 1,4-dioxane, strain ENV478 degraded this compound for > 80 days in aquifer microcosms. Our results suggest that the inability of strain ENV478 and possibly other THF-degrading bacteria to grow on 1,4-dioxane is related to their inability to efficiently metabolize the 1,4-dioxane degradation product 2HEAA but that strain ENV478 may nonetheless be useful as a biocatalyst for remediating 1,4-dioxane-contaminated aquifers.
| S-EPMC1538739 | biostudies-literature
Project description:The npd gene cluster, which encodes the enzymes of a p-nitrophenol catabolic pathway from Arthrobacter sp. strain JS443, was cloned and sequenced. Three genes, npdB, npdA1, and npdA2, were independently expressed in Escherichia coli in order to confirm the identities of their gene products. NpdA2 is a p-nitrophenol monooxygenase belonging to the two-component flavin-diffusible monooxygenase family of reduced flavin-dependent monooxygenases. NpdA1 is an NADH-dependent flavin reductase, and NpdB is a hydroxyquinol 1,2-dioxygenase. The npd gene cluster also includes a putative maleylacetate reductase gene, npdC. In an in vitro assay containing NpdA2, an E. coli lysate transforms p-nitrophenol stoichiometrically to hydroquinone and hydroxyquinol. It was concluded that the p-nitrophenol catabolic pathway in JS443 most likely begins with a two-step transformation of p-nitrophenol to hydroxy-1,4-benzoquinone, catalyzed by NpdA2. Hydroxy-1,4-benzoquinone is reduced to hydroxyquinol, which is degraded through the hydroxyquinol ortho cleavage pathway. The hydroquinone detected in vitro is a dead-end product most likely resulting from chemical or enzymatic reduction of the hypothetical intermediate 1,4-benzoquinone. NpdA2 hydroxylates a broad range of chloro- and nitro-substituted phenols, resorcinols, and catechols. Only p-nitro- or p-chloro-substituted phenols are hydroxylated twice. Other substrates are hydroxylated once, always at a position para to a hydroxyl group.
| S-EPMC2168711 | biostudies-literature
Project description:2,4-Dinitroanisole (DNAN) is an insensitive munition ingredient used in explosive formulations as a replacement for 2,4,6-trinitrotoluene (TNT). Little is known about the environmental behavior of DNAN. There are reports of microbial transformation to dead-end products, but no bacteria with complete biodegradation capability have been reported. Nocardioides sp. strain JS1661 was isolated from activated sludge based on its ability to grow on DNAN as the sole source of carbon and energy. Enzyme assays indicated that the first reaction involves hydrolytic release of methanol to form 2,4-dinitrophenol (2,4-DNP). Growth yield and enzyme assays indicated that 2,4-DNP underwent subsequent degradation by a previously established pathway involving formation of a hydride-Meisenheimer complex and release of nitrite. Identification of the genes encoding the key enzymes suggested recent evolution of the pathway by recruitment of a novel hydrolase to extend the well-characterized 2,4-DNP pathway.
| S-EPMC4249229 | biostudies-literature
Project description:The isolation of propiconazole (PCZ) degrading bacterium BBK_9 strain was done from paddy soil, and it was identified as Burkholderia sp. based on the morphological characteristics and biochemical properties combined with 16S rRNA gene sequencing analysis. It has been seen that the factors such as temperature and pH influence the biodegradation process. The role of plasmid was studied in the degradation process by plasmid curing method. The PCZ acts as the sole carbon source and as energy substrate which can be utilized by the strain for its growth in Mineral salt medium and degraded 8.89 µg ml-1 of PCZ at 30 °C and pH 7 within 4 days. During the bioconversion process of PCZ, three metabolite were formed such as 1-(2,4-dichlorophenyl)-2-(1H-1,2,4-triazol-1-yl) ethanone, 1-[2-(4-chlorophenyl) ethyl]-1H-1,2,4-triazole and 1-ethyl-1H-1,2,4-triazole. The LD50 value of BBK_9 strain was determined with acridine orange which resulted in 40 µg ml-1 at cell density of 0.243 at 660 nm. Furthermore, plasmid curing was done using LD50 concentration and from that three plasmids got cured in the sixth generation. It was found that, cured strain was able to degrade 7.37 µg ml-1 of PCZ, indicating the plasmid encoded gene were not responsible for the PCZ degradation. On the source of these outcomes, strain BBK_9 can be used as potential strain for bioremediation of contaminated sites.
| S-EPMC5398191 | biostudies-literature
Project description:Pseudomonas sp. strain NEE2 isolated from oil-polluted soils could biodegrade n-hexane effectively. In this study, the secretory product of n-hexane biodegradation by NEE2 was extracted, characterized, and investigated on the secretory product's enhanced effect on n-hexane removal. The effects of various biodegradation conditions on n-hexane removal by NEE2, including nitrogen source, pH value, and temperature were also investigated. Results showed that the secretory product lowered surface tension of water from 72 to 40 mN/m, with a critical micelle concentration of 340?mg/L, demonstrating that there existed biosurfactants in the secretory product. The secretory product at 50?mg/L enhanced n-hexane removal by 144.4% within 48?h than the control group. The optimum conditions for n-hexane removal by NEE2 were at temperature of 25-30?°C, pH value of 7-8, and (NH4)2SO4 as nitrogen source. Besides n-hexane, NEE2 could also utilize a variety of carbon sources. These results proved that NEE2 can consume hydrophobic volatile organic compounds (VOCs) to produce biosurfactants which can further enhance hydrophobic VOCs degradation.
| S-EPMC6851123 | biostudies-literature
Project description:A strain designated TFA which very efficiently utilizes tetralin has been isolated from the Rhine river. The strain has been identified as Sphingomonas macrogoltabidus, based on 16S rDNA sequence similarity. Genetic analysis of tetralin biodegradation has been performed by insertion mutagenesis and by physical analysis and analysis of complementation between the mutants. The genes involved in tetralin utilization are clustered in a region of 9 kb, comprising at least five genes grouped in two divergently transcribed operons.
| S-EPMC91258 | biostudies-literature