Nocardioides Simplex Research Articles

Cholesterol Assay Based on Recombinant Cholesterol Oxidase, ABTS, and Horseradish Peroxidase.

Cholesterol determination by cholesterol oxidase reaction is a fast, convenient, and highly specific approach with widespread use in clinical diagnostics. Routinely, endpoint measurements with 4-aminophenazone or 4-aminoantipyrine as chromogens and sodium cholate, surfactants, or alcohols as solubilizing agents are used. Here we describe a novel kinetic method to determine cholesterol in 0.05-0.75mM range in neutral or acidic buffers by use of recombinant cholesterol oxidase from Nocardioides simplex in a coupled reaction with horseradish peroxidase, ABTS as a chromogen, and methyl-β-cyclodextrin as a solubilizing agent.

Screening for Microbial Metal-Chelating Siderophores for the Removal of Metal Ions from Solutions.

To guarantee the supply of critical elements in the future, the development of new technologies is essential. Siderophores have high potential in the recovery and recycling of valuable metals due to their metal-chelating properties. Using the Chrome azurol S assay, 75 bacterial strains were screened to obtain a high-yield siderophore with the ability to complex valuable critical metal ions. The siderophore production of the four selected strains Nocardioides simplex 3E, Pseudomonas chlororaphis DSM 50083, Variovorax paradoxus EPS, and Rhodococcus erythropolis B7g was optimized, resulting in significantly increased siderophore production of N. simplex and R. erythropolis. Produced siderophore amounts and velocities were highly dependent on the carbon source. The genomes of N. simplex and P. chlororaphis were sequenced. Bioinformatical analyses revealed the occurrence of an achromobactin and a pyoverdine gene cluster in P. chlororaphis, a heterobactin and a requichelin gene cluster in R. erythropolis, and a desferrioxamine gene cluster in N. simplex. Finally, the results of the previous metal-binding screening were validated by a proof-of-concept development for the recovery of metal ions from aqueous solutions utilizing C18 columns functionalized with siderophores. We demonstrated the recovery of the critical metal ions V(III), Ga(III), and In(III) from mixed metal solutions with immobilized siderophores of N. simplex and R. erythropolis.

Genome-Wide Transcriptome Profiling Provides Insight on Cholesterol and Lithocholate Degradation Mechanisms in Nocardioides simplex VKM Ac-2033D.

Steroid microbial degradation plays a significant ecological role for biomass decomposition and removal/detoxification of steroid pollutants. In this study, the initial steps of cholesterol degradation and lithocholate bioconversion by a strain with enhanced 3-ketosteroid dehydrogenase (3-KSD) activity, Nocardioides simplex VKM Ac-2033D, were studied. Biochemical, transcriptomic, and bioinformatic approaches were used. Among the intermediates of sterol sidechain oxidation cholest-5-en-26-oic acid and 3-oxo-cholesta-1,4-dien-26-oic acid were identified as those that have not been earlier reported for N. simplex and related species. The transcriptomic approach revealed candidate genes of cholesterol and lithocholic acid (LCA) catabolism by the strain. A separate set of genes combined in cluster and additional 3-ketosteroid Δ1-dehydrogenase and 3-ketosteroid 9α-hydroxylases that might be involved in LCA catabolism were predicted. Bioinformatic calculations based on transcriptomic data showed the existence of a previously unknown transcription factor, which regulates cholate catabolism gene orthologs. The results contribute to the knowledge on diversity of steroid catabolism regulation in actinobacteria and might be used at the engineering of microbial catalysts for ecological and industrial biotechnology.

Bioconversion of 6-(N-methyl-N-phenyl)aminomethyl androstane steroids by Nocardioides simplex

The newly synthesized (α/β)-diastereomers of 6-(N-methyl-N-phenyl)aminomethylandrost-4-ene-3,17-dione (5) and 6-(N-methyl-N-phenyl)aminomethylandrost-4-en-17β-ol-3-one (6) were firstly investigated as substrates for the whole cells of Nocardioides simplex VKM Ac-2033D in comparison with their unsubstituted analogs, – androst-4-ene-3,17-dione (1) and androst-4-en-17β-ol-3-one (2).1(2)-Dehydroderivatives were identified as the major bioconversion products from all the substrates tested. When using the mixtures of (α/β)-stereoisomers of 5 and 6 as the substrates, only β-stereoisomers of the corresponding 1,4-diene-steroids were formed. Along with 1(2)-dehydrogenation, N. simplex VKM Ac-2033D promoted oxidation of the hydroxyl group at C-17 position of 6: both 6(α) and 6(β) were transformed to the corresponding 17-keto derivatives. No steroid core destruction was observed during the conversion of the 6-substituted androstanes 5 and 6, while it was significant when 1 or 2 was used as the substrate.The results suggested high potentials of N. simplex VKM Ac-2033D for the generation of novel 1(2)-dehydroanalogs.

Nocardioides flava sp. nov., isolated from rhizosphere of poppy plant, Republic of Korea.

Phylogenetic and taxonomic characterization was performed for bacterium, designated strain THG-DN5.4(T), isolated from the rhizosphere of poppy plant collected from Gyeryongsan, Republic of Korea. Strain THG-DN5.4(T) consists of Gram-stain-positive, aerobic, non-motile rods. The bacteria grow optimally at 18-30 °C, at pH 7.0 and in the presence of 0.5-1.0 % NaCl. Based on 16S rRNA gene sequence analysis, strain THG-DN5.4(T) was found to be most closely related to Nocardioides nitrophenolicus KCTC 047BP(T), followed by Nocardioides ginsengisoli KCTC 19135(T), Nocardioides kongjuensis KCTC 19054(T), Nocardioides simplex KACC 20620(T), Nocardioides aromaticivorans KACC 20613(T), Nocardioides daeguensis KCTC 19799(T) and Nocardioides caeni KCTC 19600(T). The DNA-DNA relatedness between strain THG-DN5.4(T) and closely related phylogenetic neighbors was below 45.0 %, and the DNA G+C content of strain THG-DN5.4(T) was 70.8 mol%. An isoprenoid quinone was identified as MK-8(H4). Strain THG-DN5.4(T) was characterized chemotaxonomically as having LL-diaminopimelic acid in the cell-wall peptidoglycan. The polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, some unidentified aminolipids and some unidentified polar lipids. iso-C16:0 and C18:1 ω9c were identified as the major fatty acids present in THG-DN5.4(T). On the basis of a polyphasic taxonomic study, strain THG-DN5.4(T) is considered to represent a novel species of the genus Nocardioides, for which the name Nocardioides flava sp. nov. is proposed. The type strain is THG-DN5.4(T) (=KCTC 39606(T)=CCTCC AB 2015298(T)).

토양 서식 미생물을 이용한 가축사체 매몰지 토양유래 용존 유기물 분해

The aim of this study was to investigate the biodegradation of dissolved organic matter derived from animal carcass disposal soil using soil inhabited bacteria and to identify the bacteria involved in the biodegradation. The two soils were obtained from the animal carcass burial sites located in Anseong, Gyeonggi-do, Korea. The results indicated that during the biodegradation experiments (56 days), 48% of dissolved organic carbon (DOC) was mineralized within 13 days in soil-derived solution 1 (initial DOC = 19.88 mgC/L), and the DOC concentration at 56 days was 8.8 ± 0.4 mg C/L, indicating 56% mineralization of DOC. In soil-derived solution 2 (initial DOC = 19.80 mgC/L), DOC was mineralized drastically within 13 days, and the DOC concentration was decreased to 6.0 ± 0.4 mg C/L at 56 days (76% mineralization of DOC). Unlike DOC value, the specific UV absorbance (SUVA254) value, an indicator of proportion of aromatic structures in total organic carbon, tended to increase until 21 days and then decreased thereafter. The SUVA254 values in soil-derived solutions 1 and 2 were the highest at 21 days. The microbial analysis demonstrated that Pseudomonas fluorescens, Achromobacter xylosoxidans, Nocardioides simplex, Pseudomonas mandelii, Bosea sp. were detected at 14 days of incubation, whereas Pseudomonas veronii appeared as a dominant species at 56 days.

Diversity of Xylanolytic Bacteria Isolated from Thai Sources

Twenty-three xylanolytic bacteria were isolated from soils, sediments and buffalo faeces collected in Thailand. They were divided into 10 groups based on the phenotypic and chemotaxonomic characteristics including 16S rRNA gene sequence analyses. Eleven isolates were Gram-positive, facultatively anaerobic, spore-forming, rod-shaped bacteria. They contained meso-diaminopimelic in cell wall peptidoglycan. Two isolates (Group IA) were identified as Bacillus subtilis, 4 isolates (Group IB) were B. licheniformis, 2 isolates (Group IC) were B. niabensis, one (Group ID) was B. nealsonii, and 2 isolates (Group IE) were B. cereus. Seven isolates were Gram-positive, non-spore-forming, rod-shaped bacteria and were identified as Isoptericola variabilis (2 isolates in Group II), as Jonesia denitrificans (2 isolates in Group III), as Microbacterium natoriense (2 isolates in Group IV), and one isolate as Nocardioides simplex (Group V). Five isolates were Gram-negative; facultatively anaerobic, non-spore-forming, rod-shaped bacteria and each of them were identified respectively as Acinetobacter junii (Group VI), Aeromonas enteropelogenes (Group VII), Pseudomonas stutzeri (Group VIII), Stenotrophomonas maltophilia (Group IX) and Zobellella denitrificans (Group X). The isolates produced xylanase activity ranged from 1.03 to 17.65±0.25 unit/ml.

Stopped flow kinetic studies on reductive half-reaction of histamine dehydrogenase from Nocardioides simplex with histamine

Histamine dehydrogenase from Nocardioides simplex (HmDH) which catalyzes the oxidative deamination of histamine is an iron-sulphur-containing flavoprotein. For our further understanding on the intramolecular electron transfer process, the reductive half reaction of HmDH with histamine has been studied by stopped flow spectrophotometry at pH 7.5 and 10. The reaction at pH 7.5 is found to be analysed on a kinetic model composed of three sequential first-order reactions. The first fast phase, of which the rate constant shows a hyperbolic dependence on the histamine concentration, is assigned to a direct two-electron reduction of the oxidized flavin (CFMN(O)) by histamine with no involvement of the semiquinone form of the flavin (CFMN(S)). The second moderate process is the substrate-independent intramolecular single-electron transfer from the reduced flavin to the oxidized iron-sulphur cluster. The third slow process is considered to reflect the second binding of histamine to CFMN(S), which is responsible for the substrate inhibition. At pH 10, the reaction is analysed with one pseudo-first-order reaction phase which is substrate-dependent two-electron reduction of CFMN(O) coupled with the subsequent fast intersubunit single-electron transfer. The UV-vis spectroscopy of HmDH suggests the deprotonation of Tyr residues, which seems to cause the switching of the electron transfer property.

Site-directed mutation at residues near the catalytic site of histamine dehydrogenase from Nocardioides simplex and its effects on substrate inhibition

Histamine dehydrogenase from Nocardioides simplex (nHmDH) is a homodimer containing one 6-S-cysteinyl FMN (CFMN) and one [4Fe-4S] cluster per monomer. nHmDH catalyses the oxidative deamination of histamine to ammonia and imidazole acetaldehyde, but histamine inhibits its catalytic activity at high concentrations. We mutated gene-encoded residues (Tyr180, Gly268 and Asp269) near CFMN to understand the biophysical meaning of the substrate inhibition. Three mutants Y180F, G268D/D269C and Y180F/G268D/D269C were expressed by considering the DNA sequence alignment of histamine dehydrogenase from Rhizobium sp. 4-9 (rHmDH), which does not suffer from the substrate inhibition. The Y180F/G268D/D269C mutation to mimic rHmDH successfully suppressed the inhibition, although the catalytic activity decreased. The substrate inhibition was weakened by the Y180F mutation, but G268D/D269C was still susceptible to the inhibition. It was found that it also causes changes in the UV-vis absorption spectra of the substrate-reduced form and the redox potential of the enzymes. The characterization suggests that the thermodynamic preference of the semiquinone form of CFMN in the two-electron-reduced subunit of the enzyme is responsible for the substrate inhibition. However, destabilization of the semiquinone form leads to kinetic hindrance due to the uphill single electron transfer from the fully reduced CFMN to the [4Fe-4S] cluster.

Nocardioides ginsengisoli sp. nov., isolated from soil of a ginseng field

A Gram-positive, rod-shaped, non-spore-forming bacterium (Gsoil 1124(T)) was isolated from soil of a ginseng field of Pocheon province in South Korea, and was characterized in order to determine its taxonomic position. On the basis of 16S rRNA gene sequence similarity, strain Gsoil 1124(T) was shown to belong to the family Nocardioidaceae and related to Nocardioides simplex (98.2 % 16S rRNA gene sequence similarity), Nocardioides aromaticivorans (98.1 %), Nocardioides nitrophenolicus (97.7 %) and Nocardioides kongjuensis (97.5 %). The sequence similarity with any other species with validly published names within the genus Nocardioides was less than 94.5 %. Strain Gsoil 1124(T) was characterized chemotaxonomically as having ll-2,6-diaminopimelic acid in the cell-wall peptidoglycan, MK-8(H(4)) as the predominant menaquinone and iso-C(16 : 0), C(18 : 0), C(16 : 0), and C(18 : 1)omega9c as the major fatty acids. The G+C content of the genomic DNA was 70.2 mol%. The chemotaxonomic properties and phenotypic characteristics supported the affiliation of strain Gsoil 1124(T) to the genus Nocardioides. The results of physiological and biochemical tests, and the low level of DNA-DNA relatedness allowed genotypic differentiation of strain Gsoil 1124(T) from recognized Nocardioides species. Therefore, strain Gsoil 1124(T) is considered to represent a novel species, for which the name Nocardioides ginsengisoli sp. nov. is proposed, with the type strain Gsoil 1124(T) (=KCTC 19135(T)=CCUG 52478(T)=DSM 17921(T)).

Nocardioides humi sp. nov., a -glucosidase-producing bacterium isolated from soil of a ginseng field

Strain DCY24(T), a Gram-reaction-positive, aerobic, rod-shaped, motile bacterium, was isolated from soil of a ginseng field in South Korea. According to 16S rRNA gene sequence analysis, it was closely related to Nocardioides aromaticivorans DSM 15131(T) (95.1 % similarity), Nocardioides simplex KCTC 9106(T) (95.0 %), Nocardioides nitrophenolicus DSM 15529(T) (94.8 %) and Nocardioides kongjuensis DSM 19082(T) (94.7 %). Chemotaxonomic data revealed that strain DCY24(T) possessed MK-8(H(4)) as the predominant menaquinone, ll-2,6-diaminopimelic acid as the diagnostic diamino acid, phosphatidylglycerol and diphosphatidylglycerol as predominant polar lipids and iso-C(16 : 0), iso-C(17 : 0) and C(18 : 1)omega9c as predominant fatty acids. The DNA G+C content was 71.0 mol%. Based on evidence from this polyphasic study, strain DCY24(T) (=KCTC 19265(T) =LMG 24128(T)) should be classified as the type strain of a novel Nocardioides species, for which the name Nocardioides humi sp. nov. is proposed.

Direct electrochemistry of histamine dehydrogenase from Nocardioides simplex

Histamine dehydrogenase from Nocardioides simplex (HmDH) belongs to the family of soluble iron–sulfur flavoproteins having one [4Fe–4S] cluster and one 6- S-cysteinyl flavin mononucleotide per monomer. Direct electrochemistry of HmDH was studied using several carbon particle-modified glassy carbon electrodes (GCEs) and indium tin oxide (ITO) electrodes. HmDH gave a clear catalytic wave of the histamine oxidation without any mediator at a GCE modified with Ketjen Black (KB) with an average particle diameter of 39.5 nm, although redox signal of the cofactors itself was not clearly recognized. Experimental data supported the irreversible adsorption of HmDH on the KB particles and the importance of the size of the carbon particle as well as the surface area as factors determining the current density of the direct electron transfer (DET)-type bioelectrocatalysis. On the other hand, HmDH was adsorbed on ITO electrodes as a monolayer, as evidenced by quartz crystal microbalance measurement, and showed a clear redox wave ascribed to the [4Fe–4S] cluster. However, some mediators were required to observe catalytic wave of histamine oxidation at ITO electrodes, indicating that the interaction between the two redox cofactors seems to be disrupted in the monomer HmDH adsorbed on the planar and hydrophilic surfaces of ITO electrodes. Surface properties of electrodes favorable for DET-type bioelectrocatalysis of HmDH are discussed.

Thermodynamic Redox Properties Governing the Half-Reduction Characteristics of Histamine Dehydrogenase fromNocardioides simplex

Histamine dehydrogenase from Nocardioides simplex is a homodimer and belongs to the family of iron-sulfur flavoproteins having one [4Fe-4S] cluster and one 6-S-cysteinyl FMN per monomer. In the reductive titration with histamine, two-electron reduction occurred per monomer at pH<9, while single-electron reduction proceeded at pH>9. The substrate-reduced histamine dehydrogenase yielded an electron paramagnetic resonance spectral signal assigned to the flavin semiquinone. The signal intensity increased with pH up to pH 9 and reached a maximum at pH>9. These unique features are explained in terms of the redox potential of the cofactors, where the redox potential was evaluated over a pH range from 7 to 10 by using a spectroelectrochemical titration method for the flavin and cyclic voltammetry for the [4Fe-4S] cluster. The bell-type pH dependence of the enzymatic activity is also discussed in terms of the pH dependence of the centers' redox potential.

Bioelectrochemical Determination at Histamine Dehydrogenase-based Electrodes

Histamine dehydrogenase (HmDH) from Nocardioides simplex was used in constructing mediated bioelectrochemical systems for histamine oxidation using Os complexes as mediators. Amperometric histamine sensor was prepared by immobilizing a mixture of HmDH and a mediator, poly(1-vinylimidazole) complexed with [Os(2,2′-dipyridylamine)2Cl], with a crosslinker, poly(ethylene glycol) diglycidyl ether on a glassy carbon electrode. The electrode responded linearly to histamine over the range from 2 to 30 µmol dm−3, became free from the substrate inhibition observed in solution, and was almost insensitive to ascorbate at pH 7.0. On the other hand, the charge in coulometry using carbon felt electrodes was proportional to the histamine amount over the range from 0.1 to 5 nmol and the slope indicates a 4-electron oxidation (2-electron in the enzyme reaction and 2-electron in follow-up electrochemical reaction).

A Simple and Rapid Method for Screening of Nocardioides simplex Mutant with High Cholesterol Oxidase Activity

A Simple and Rapid Method for Screening of Nocardioides simplex Mutant with High Cholesterol Oxidase Activity

A Fermentation Product of Phytosterol Including Campestenone Reduces Body Fat Storage and Body Weight Gain in Mice

Anti-obesity effects of a fermentation product of phytosterols including campestenone in ICR mice were investigated. Five-week-old male ICR mice were fed by the pair-feeding method for 8 wk. Experimental feed was prepared by adding TO-001, a phytostenone mixture produced by fermentation of phytosterols using Nocardioides simplex, at 0.25, 0.5, 1.0, or 2.0% or no additive to a high fat diet (fat 20%). Mice fed a stock feed (fat 5.6%) ad libitum were used as the standard growth group. In animals fed the high fat diet, control (no added TO-001) mice showed a weight gain that was about 10% higher than for the standard growth group. TO-001 reduced body weight dose-dependently. Final body weights of 0.5% and 1.0% TO-001-fed mice were lowered by about 9% and those of 2.0% TO-00 I-fed mice by about 12% compared with the control mice. Visceral and subcutaneous fat weight in mice fed TO-001 was significantly lower than that in mice fed the control diet. The concentrations of serum triglyceride (TG) and total cholesterol (TC) were significantly lower in the 1.0% and/or 2.0% TO-001-fed mice. Furthermore, levels of liver TG and TC were decreased in the TO-001-fed group. Increase of total lipid excretion in the feces was dose dependent. No obvious abnormalities due to consumption of TO-001 were detected by a blood biochemical examination, clinical observations or necropsy. The results suggested that TO-001, a fermentation product of phytosterols, may be a promising component of dietetic functional foods.

Histamine dehydrogenase from Rhizobium sp.: Gene cloning, expression in Escherichia coli, characterization and application to histamine determination

The gene encoding histamine dehydrogenase in Rhizobium sp. 4-9 has been cloned and overexpressed in Escherichia coli. The coding region of the gene was 2079 bp and encoded a protein of 693 amino acids with a calculated molecular mass of 76,732 Da. This histamine dehydrogenase was related to histamine dehydrogenase from Nocardioides simplex (54.5% identical), trimethylamine dehydrogenase from Methylophilus methylotrophus (39.3% identical) and dimethylamine dehydrogenase from Hyphomicrobium X (38.1% identical), which have a covalent 6- S-cysteinyl flavin mononucleotide and a [4Fe–4S] cluster as redox cofactors. Sequence alignment and a UV–visible absorption spectrum supported the presence of these cofactors in this histamine dehydrogenase. The investigation of the enzymatic properties suggested that this enzyme exhibited the most excellent substrate specificity toward histamine among all amine oxidases or dehydrogenases found to date. The recombinant enzyme was able to be used for the colorimetric determination of histamine, which gave a linear calibration curve and identical data with conventional methods.

Production of Completely Flavinylated Histamine Dehydrogenase, Unique Covalently Bound Flavin, and Iron–Sulfur Cluster-Containing Enzyme ofNocardioides simplexinEscherichia coli, and Its Properties

The hmd gene of histamine dehydrogenase from Nocardioides simplex was overexpressed in Escherichia coli, and the resulting enzyme was purified to homogeneity. The purified recombinant enzyme is almost identical with the native enzyme in view of molecular weight and specific activity, and is stoichiometrically assembled with the three cofactors 6-S-cysteinyl FMN, 4Fe-4S cluster, and ADP.

Cloning and characterization of histamine dehydrogenase from Nocardioides simplex

Histamine dehydrogenase (NSHADH) can be isolated from cultures of Nocardioides simplex grown with histamine as the sole nitrogen source. A previous report suggested that NSHADH might contain the quinone cofactor tryptophan tryptophyl quinone (TTQ). Here, the hdh gene encoding NSHADH is cloned from the genomic DNA of N. simplex, and the isolated enzyme is subjected to a full spectroscopic characterization. Protein sequence alignment shows NSHADH to be related to trimethylamine dehydrogenase (TMADH: EC 1.5.99.7), where the latter contains a bacterial ferredoxin-type [4Fe–4S] cluster and 6- S-cysteinyl FMN cofactor. NSHADH has no sequence similarity to any TTQ containing amine dehydrogenases. NSHADH contains 3.6 ± 0.3 mol Fe and 3.7 ± 0.2 mol acid labile S per subunit. A comparison of the UV/vis spectra of NSHADH and TMADH shows significant similarity. The EPR spectrum of histamine reduced NSHADH also supports the presence of the flavin and [4Fe–4S] cofactors. Importantly, we show that NSHADH has a narrow substrate specificity, oxidizing only histamine ( K m = 31 ± 11 μM, k cat/ K m = 2.1 (± 0.4) × 10 5 M −1 s −1), agmatine ( K m = 37 ± 6 μM, k cat/ K m = 6.0 (± 0.6) × 10 4 M −1 s −1), and putrescine ( K m = 1280 ± 240 μM, k cat/ K m = 1500 ± 200 M −1 s −1). A kinetic characterization of the oxidative deamination of histamine by NSHADH is presented that includes the pH dependence of k cat/ K m (histamine) and the measurement of a substrate deuterium isotope effect, D( k cat/ K m (histamine)) = 7.0 ± 1.8 at pH 8.5. k cat is also pH dependent and has a reduced substrate deuterium isotope of D( k cat) = 1.3 ± 0.2.

Nocardioides aromaticivorans sp. nov., a dibenzofuran-degrading bacterium isolated from dioxin-polluted environments

Seven strains of dibenzofuran (DF)-degrading bacteria isolated from dioxin-polluted environments were characterized. These isolates were able to grow with dibenzofuran as the sole carbon and energy source. During the growth with dibenzofuran, they produced a soluble yellow metabolite that exhibited a unique pH-dependent shift of absorption maxima. Dibenzo- p-dioxin and biphenyl were also degraded with pigment production. The isolates were strictly aerobic and chemoorganotrophic and had Gram-positive, nonmotile, rod-shaped cells. Chemotaxonomic analyses showed that cells contained L, L-diaminopimeric acid in the peptidoglycan, branched-chain fatty acids as major fatty acids, and menaquinone MK-8(H 4) as the sole respiratory quinone. The G+C content of the DNA of the isolates ranged from 72.0 to 72.4 mol%. The 16S rRNA gene sequences of the isolates were very similar to each other (⩾99.8%). The phylogenetic analysis showed that the isolates formed a cluster with species of the genus Nocardioides with Nocardioides simplex and Nocardioides nitrophenolicus as their nearest neighbors. DNA–DNA hybridization studies showed that the isolates showed a hybridization level of less than 55% to any tested species of the genus Nocardioides. Based on these data, Nocardioides aromaticivorans sp. nov. is proposed for the new DF-degrading isolates. The type strain is strain H-1 (IAM 14992, JCM 11674, DSM 15131).