Biodegradation of erythromycin by Delftia lacustris RJJ-61 and characterization of its erythromycin esterase.

The residual erythromycin in fermentation waste can pollute the environment and threaten human health. However, there are no effective approaches to remedy this issue. In this study, an erythromycin-degrading bacterium named RJJ-61 was isolated and identified as a strain of Delftia lacustris based on morphological and phylogenetic analyses. The degradation ability of this strain was also evaluated; it could degrade 45.18% of erythromycin at 35°C in 120 h. Furthermore, the key degradation gene ereA was cloned from strain RJJ-61 and expressed in Escherichia coli BL21; the molecular weight of the expressed protein was ~45 kDa. The enzyme activity of EreA was 108.0 mU ml-1 at 35°C and pH 7.0. Finally, the EreA protein was used to degrade erythromycin from mycelial dregs and 50% diluted solution, and the removal rates in them were 41.42% and 69.78%, respectively. In summary, D. lacustris RJJ-61 is a novel erythromycin-degrading strain that has great potential to remove erythromycin pollutants from the environment.

Class†III Polyphosphate Kinase†2 Enzymes Catalyze the Pyrophosphorylation of Adenosine-5'-Monophosphate.

Polyphosphate kinase 2 (PPK2) transfer phosphate from inorganic polyphosphate to nucleotides. According to their activity, PPK2 enzymes are classified into three groups. Among them, class III enzymes catalyze both the phosphorylation of nucleotide mono- to diphosphates and di- to triphosphates by using polyphosphate, which is a very inexpensive substrate. Therefore, class III enzymes are very attractive for use in biotechnological applications. Despite several studies on class III enzymes, a detailed mechanism of how phosphate is transferred from the polyphosphate to the nucleotide remains to be elucidated. Herein, it is reported that PPK2 class III enzymes from two different bacterial species catalyze the phosphorylation of adenosine mono- (AMP) into triphosphate (ATP) not only through step-by-step phosphorylation, but also by pyrophosphorylation. These are the first PPK2 enzymes that have been shown to possess polyphosphate-dependent pyrophosphorylation activity.

Discovery of novel highly active and stable aspartate dehydrogenases.

Aspartate family amino acids (AFAAs) have important commercial values due to their wide spectrum of applications. Most if not all AFAAs are produced under aerobic conditions which is energy-intensive. To establish a cost-effective anaerobic process for production of AFAAs, it holds great promise to develop a new pathway enabling the conversion of oxoloacetate into aspartate through direct amination which is catalyzed by aspartate dehydrogenase (AspDH). Compared with the well studied aspartate aminotransferase and aspartate ammonia-lyase, only a few AspDHs are characterized till date, and failure to reproduce the high activity of AspDH from Rastonia eutropha documented in the literature encouraged us to screen and characterize novel AspDHs from different origins. Interestingly, the AspDHs from Klebsiella pneumoniae 34618 (KpnAspDH) and Delftia sp. Cs1-4 (DelAspDH) showed successful soluble expression. KpnAspDH and DelAspDH containing C-terminal hexa-histidine tags were purified and characterized for their catalytic properties. Notably, in addition to its high reductive amination activity, DelAspDH exhibited considerable stability as compared to the other source of AspDHs. This work thus provides novel enzyme resource for engineering strains capable of producing AFAAs under anaerobic conditions.

Exploitation and characterization of three versatile amidase super family members from Delftia tsuruhatensis ZJB-05174.

Amidases can be assigned into two families according to their amino acid sequences. Three amidases (Dt-Amis) were mined and identified from genome of Delftia tsuruhatensis. Homology analysis demonstrated that Dt-Ami 2 and Dt-Ami 6 belonged to amidase signature (AS) family, while Dt-Ami 7 belonged to nitrilase superfamily. AS amidases were shown to hydrolyze a wide spectrum of amides. Kinetic analysis demonstrated that the extension of chain length of aliphatic amides considerably decreased the Km values, and the turnover numbers (kcat) were high with linear aliphatic amides as substrates. Dt-Ami 2 showed maximum activity near a quite alkaline pH (11.0) and exhibited opposite enantioselectivity to Dt-Ami 6. Furthermore, a novel bioprocess for hydrolysis of 1-cyanocyclohexaneacetamide was developed using Dt-Ami 6 as biocatalyst, resulting in >99% conversion within 1.5h at a substrate loading of 100g/L by 0.5g/L of Escherichia coli cells. On the other hand, nitrilase superfamily amidase only hydrolyzed aliphatic amides. The Km values of Dt-Ami 7 were considerably increased with the extension of chain length of aliphatic amides. The characterized enzymes from different families showed distinct biochemical characteristics and catalytic properties, leading to a better understanding of the two super amidase family members.

Metabolic pathway involved in 2-methyl-6-ethylaniline degradation by Sphingobium sp. strain MEA3-1 and cloning of the novel flavin-dependent monooxygenase system meaBA.

2-Methyl-6-ethylaniline (MEA) is the main microbial degradation intermediate of the chloroacetanilide herbicides acetochlor and metolachlor. Sphingobium sp. strain MEA3-1 can utilize MEA and various alkyl-substituted aniline and phenol compounds as sole carbon and energy sources for growth. We isolated the mutant strain MEA3-1Mut, which converts MEA only to 2-methyl-6-ethyl-hydroquinone (MEHQ) and 2-methyl-6-ethyl-benzoquinone (MEBQ). MEA may be oxidized by the P450 monooxygenase system to 4-hydroxy-2-methyl-6-ethylaniline (4-OH-MEA), which can be hydrolytically spontaneously deaminated to MEBQ or MEHQ. The MEA microbial metabolic pathway was reconstituted based on the substrate spectra and identification of the intermediate metabolites in both the wild-type and mutant strains. Plasmidome sequencing indicated that both strains harbored 7 plasmids with sizes ranging from 6,108 bp to 287,745 bp. Among the 7 plasmids, 6 were identical, and pMEA02' in strain MEA3-1Mut lost a 37,000-bp fragment compared to pMEA02 in strain MEA3-1. Two-dimensional electrophoresis (2-DE) and protein mass fingerprinting (PMF) showed that MEA3-1Mut lost the two-component flavin-dependent monooxygenase (TC-FDM) MeaBA, which was encoded by a gene in the lost fragment of pMEA02. MeaA shared 22% to 25% amino acid sequence identity with oxygenase components of some TC-FDMs, whereas MeaB showed no sequence identity with the reductase components of those TC-FDMs. Complementation with meaBA in MEA3-1Mut and heterologous expression in Pseudomonas putida strain KT2440 resulted in the production of an active MEHQ monooxygenase.

Interference of Quorum Sensing by Delftia sp. VM4 Depends on the Activity of a Novel N-Acylhomoserine Lactone-Acylase.

BACKGROUND: Turf soil bacterial isolate Delftia sp. VM4 can degrade exogenous N-acyl homoserine lactone (AHL), hence it effectively attenuates the virulence of bacterial soft rot pathogen Pectobacterium carotovorum subsp. carotovorum strain BR1 (Pcc BR1) as a consequence of quorum sensing inhibition. METHODOLOGY/PRINCIPAL FINDINGS: Isolated Delftia sp. VM4 can grow in minimal medium supplemented with AHL as a sole source of carbon and energy. It also possesses the ability to degrade various AHL molecules in a short time interval. Delftia sp. VM4 suppresses AHL accumulation and the production of virulence determinant enzymes by Pcc BR1 without interference of the growth during co-culture cultivation. The quorum quenching activity was lost after the treatment with trypsin and proteinase K. The protein with quorum quenching activity was purified by three step process. Matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) and Mass spectrometry (MS/MS) analysis revealed that the AHL degrading enzyme (82 kDa) demonstrates homology with the NCBI database hypothetical protein (Daci_4366) of D. acidovorans SPH-1. The purified AHL acylase of Delftia sp. VM4 demonstrated optimum activity at 20-40°C and pH 6.2 as well as AHL acylase type mode of action. It possesses similarity with an α/ß-hydrolase fold protein, which makes it unique among the known AHL acylases with domains of the N-terminal nucleophile (Ntn)-hydrolase superfamily. In addition, the kinetic and thermodynamic parameters for hydrolysis of the different AHL substrates by purified AHL-acylase were estimated. Here we present the studies that investigate the mode of action and kinetics of AHL-degradation by purified AHL acylase from Delftia sp. VM4. SIGNIFICANCE: We characterized an AHL-inactivating enzyme from Delftia sp. VM4, identified as AHL acylase showing distinctive similarity with α/ß-hydrolase fold protein, described its biochemical and thermodynamic properties for the first time and revealed its potential application as an anti-virulence agent against bacterial soft rot pathogen Pectobacterium carotovorum subsp. carotovorum based on quorum quenching mechanism.

Soluble Expression of (+)-γ-Lactamase in Bacillus subtilis for the Enantioselective Preparation of Abacavir Precursor.

Chiral Vince lactam (γ-lactam) is an important precursor of many carbocyclic nucleoside analogues and pharmaceuticals. Here, a (+)-γ-lactamase encoding gene delm from Delftia sp. CGMCC 5755 was identified through genome hunting. To achieve its soluble and functional expression, Escherichia coli and Bacillus subtilis expression systems were introduced. Compared with E. coli system, recombinant (+)-γ-lactamase showed improved protein solubility and catalytic activity in B. subtilis 168. Reaction conditions for enantioselective resolution of γ-lactam were optimized to be at 30 °C, pH 9.0, and 300 rpm when employing the recombinant B. subtilis 168/pMA5-delm whole cells. Kinetic analysis showed that the apparent V max and K m were 0.595 mmol/(min · gDCW) and 378 mmol/L, respectively. No obvious substrate inhibition was observed. In a 500-mL reaction system, enantioselective resolution of 100 g/L γ-lactam was achieved with 10 g/L dry cells, resulting in 55.2 % conversion and 99 % ee of (-)-γ-lactam. All above suggested that recombinant B. subtilis 168/pMA5-delm could potentially be applied in the preparation of optically pure (-)-γ-lactam.

Structural insights into the substrate stereospecificity of D-threo-3-hydroxyaspartate dehydratase from Delftia sp. HT23: a useful enzyme for the synthesis of optically pure L-threo- and D-erythro-3-hydroxyaspartate.

D-threo-3-Hydroxyaspartate dehydratase (D-THA DH) is a fold-type III pyridoxal 5'-phosphate-dependent enzyme, isolated from a soil bacterium of Delftia sp. HT23. It catalyzes the dehydration of D-threo-3-hydroxyaspartate (D-THA) and L-erythro-3-hydroxyaspartate (L-EHA). To elucidate the mechanism of substrate stereospecificity, crystal structures of D-THA DH were determined in complex with various ligands, such as an inhibitor (D-erythro-3-hydroxyaspartate (D-EHA)), a substrate (L-EHA), and the reaction intermediate (2-amino maleic acid). The C (ß) -OH of L-EHA occupied a position close to the active-site Mg(2+), clearly indicating a possibility of metal-assisted C (ß) -OH elimination from the substrate. In contrast, the C (ß) -OH of an inhibitor was bound far from the active-site Mg(2+). This suggests that the substrate specificity of D-THA DH is determined by the orientation of the C (ß) -OH at the active site, whose spatial arrangement is compatible with the 3R configuration of 3-hydroxyaspartate. We also report an optically pure synthesis of L-threo-3-hydroxyaspartate (L-THA) and D-EHA, promising intermediates for the synthesis of ß-benzyloxyaspartate, by using a purified D-THA DH as a biocatalyst for the resolution of racemic DL-threo-3-hydroxyaspartate (DL-THA) and DL-erythro-3-hydroxyaspartate (DL-EHA). Considering 50 % of the theoretical maximum, efficient yields of L-THA (38.9 %) and D-EHA (48.9 %) as isolated crystals were achieved with >99 % enantiomeric excess (e.e.). The results of nuclear magnetic resonance signals verified the chemical purity of the products. We were directly able to isolate analytically pure compounds by the recrystallization of acidified reaction mixtures (pH 2.0) and thus avoiding the use of environmentally harmful organic solvents for the chromatographic purification.

Purification of an amide hydrolase DamH from Delftia sp. T3-6 and its gene cloning, expression, and biochemical characterization.

A highly active amide hydrolase (DamH) was purified from Delftia sp. T3-6 using ammonium sulfate precipitation, diethylaminoethyl anion exchange, hydrophobic interaction chromatography, and Sephadex G-200 gel filtration. The molecular mass of the purified enzyme was estimated to be 32 kDa by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The sequence of the N-terminal 15 amino acid residues was determined to be Gly-Thr-Ser-Pro-Gln-Ser-Asp-Phe-Leu-Arg-Ala-Leu-Phe-Gln-Ser. Based on the N-terminal sequence and results of peptide mass fingerprints, the gene (damH) was cloned by PCR amplification and expressed in Escherichia coli BL21(DE3). DamH was a bifunctional hydrolase showing activity to amide and ester bonds. The specific activities of recombinant DamH were 5,036 U/mg for 2'-methyl-6'-ethyl-2- chloroacetanilide (CMEPA) (amide hydrolase function) and 612 U/mg for 4-nitrophenyl acetate (esterase function). The optimum substrate of DamH was CMEPA, with K m and k cat values of 0.197 mM and 2,804.32 s(-1), respectively. DamH could also hydrolyze esters such as 4-nitrophenyl acetate, glycerol tributyrate, and caprolactone. The optimal pH and temperature for recombinant DamH were 6.5 and 35 °C, respectively; the enzyme was activated by Mn(2+) and inhibited by Cu(2+), Zn(2+), Ni(2+), and Fe(2+). DamH was inhibited strongly by phenylmethylsulfonyl and SDS and weakly by ethylenediaminetetraacetic acid and dimethyl sulfoxide.

Crystallization and preliminary X-ray diffraction studies of D-threo-3-hydroxyaspartate dehydratase isolated from Delftia sp. HT23.

D-threo-3-Hydroxyaspartate dehydratase (D-THA DH) isolated from the soil bacterium Delftia sp. HT23 is a novel enzyme consisting of 380 amino-acid residues which catalyzes the conversion of D-threo-3-hydroxyaspartate to oxaloacetate and ammonia. D-THA DH also catalyzes the dehydration of L-threo-3-hydroxyaspartate, L-erythro-3-hydroxyaspartate and D-serine. The amino-acid sequence of D-THA DH shows significant similarity to that of two eukaryotic D-serine dehydratases derived from Saccharomyces cerevisiae and chicken kidney. D-THA DH is classified into the fold-type III group of pyridoxal enzymes and is the first example of a fold-type III dehydratase derived from a prokaryote. Overexpression of recombinant D-THA DH was carried out using a Rhodococcus erythropolis expression system and the obtained protein was subsequently purified and crystallized. The crystals of D-THA DH belonged to space group I4122, with unit-cell parameters a=b=157.3, c=157.9 Å. Single-wavelength anomalous diffraction data were collected to a resolution of 2.0 Šusing synchrotron radiation at the wavelength of the Br K absorption edge.

Synergistic removal of aniline by carbon nanotubes and the enzymes of Delftia sp. XYJ6.

Synergistic removal of aniline by carbon nanotubes and the enzymes of Delftia sp. XYJ6, a newly isolated bacterial strain for biodegrading aniline, was investigated. It showed that biodegradation rate of aniline was increased with the augment of protein concentration in cell-free extract of Delftia sp. XYJ6. The adsorption amount of aniline by multi-walled carbon nanotubes (MWCNTs) was slightly higher than that by single-walled carbon nanotubes (SWCNTs), however the adsorption amount of protein of Delftia sp. XYJ6 by MWCNTs was lower than that by SWCNTs. Much more amount of aniline could be removed by CE of Delftia sp. XYJ6 in the presence of SWCNTs than MWCNTs, which indicated that an efficient reaction between aniline and enzymes of Delftia sp. XYJ6 on the surface of SWCNTs played a key role in the rapid enzymatic biodegradation of aniline. This study is not previously reported and may be useful in basic research and the removal of aniline from wastewater.

Delftia sp. JD2: a potential Cr(VI)-reducing agent with plant growth-promoting activity.

A chromium (Cr)-resistant bacterium isolated from soil containing 6,000 mg/kg of Cr was identified based on 16S rRNA gene sequence analysis as Delftia, and designated as JD2. Growth of JD2 was accompanied with reduction of Cr(VI) to Cr(III) in liquid medium initially containing 100 mg/L Cr(VI), the maximum concentration allowing growth. JD2 showed NADH/NADPH-dependent reductase activity associated with the soluble fraction of cells. The results suggest that JD2 might be a good candidate for the treatment of highly Cr(VI)-contaminated water and/or industrial effluents. The isolate produced indole-3-acetic acid in the presence and absence of Cr(VI) and showed free-living nitrogen-fixing activity possibly attributable to a V-nitrogenase. JD2 did not counteract the harmful effect of Cr(VI) during leguminous plant growth and nodulation by rhizobial strains but functioned as a "helper" bacterium to enhance the performance of rhizobial inoculant strains during inoculation of alfalfa and clover (used as model plants to study plant growth-promoting activity) in the absence of Cr(VI).

Beta-1,3-glucanase from Delftia tsuruhatensis strain MV01 and its potential application in vinification.

During vinification microbial activities can spoil wine quality. As the wine-related lactic acid bacterium Pediococcus parvulus is able to produce slimes consisting of a ß-1,3-glucan, must and wine filtration can be difficult or impossible. In addition, the metabolic activities of several wild-type yeasts can also negatively affect wine quality. Therefore, there is a need for measures to degrade the exopolysaccharide from Pediococcus parvulus and to inhibit the growth of certain yeasts. We examined an extracellular ß-1,3-glucanase from Delftia tsuruhatensis strain MV01 with regard to its ability to hydrolyze both polymers, the ß-1,3-glucan from Pediococcus and that from yeast cell walls. The 29-kDa glycolytic enzyme was purified to homogeneity. It exhibited an optimal activity at 50°C and pH 4.0. The sequencing of the N terminus revealed significant similarities to ß-1,3-glucanases from different bacteria. In addition, the investigations indicated that this hydrolytic enzyme is still active under wine-relevant parameters such as elevated ethanol, sulfite, and phenol concentrations as well as at low pH values. Therefore, the characterized enzyme seems to be a useful tool to prevent slime production and undesirable yeast growth during vinification.

Purification, characterization and amino acid sequence of a novel enzyme, D-threo-3-hydroxyaspartate dehydratase, from Delftia sp. HT23.

D-threo-3-hydroxyaspartate dehydratase (D-THA DH) was purified from the cell-free extract of the soil-isolated bacterium Delftia sp. HT23. The enzyme exhibited dehydratase activity towards D-threo-3-hydroxyaspartate, l-threo-3-hydroxyaspartate, l-erythro-3-hydroxyaspartate and d-serine. Absorption of the purified enzyme at 412 nm suggests that it contains pyridoxal 5'-phosphate (PLP) as a cofactor. The NH(2)-terminal and internal amino acid sequences showed significant similarity to hypothetical alanine racemase of genome-sequenced Delftia acidovorans SPH-1; however, the purified enzyme showed no alanine racemase activity. Using the sequence information of D. acidovorans SPH-1, the gene encoding d-THA DH was cloned. The deduced amino acid sequence, which belongs to the alanine racemase family, shows significant (26-36%) similarity to d-serine dehydratase of both Saccharomyces cerevisiae and chicken. In order to obtain purified d-THA DH efficiently, the gene was expressed in Escherichia coli. The recombinant enzyme was highly activated by divalent cations, such as Mn(2+), Co(2+) and Ni(2+). Site-directed mutagenesis experiment revealed that lysine 43 is an important residue involved in PLP binding and catalysis. This is the first reported enzyme that acts on d-THA. In addition, this enzyme is the first example of a prokaryotic dehydratase belonging to the fold-type III PLP-dependent enzyme family.

Biodegradation of 2-chloroaniline, 3-chloroaniline, and 4-chloroaniline by a novel strain Delftia tsuruhatensis H1.

A new strain Delftia tsuruhatensis H1 able to degrade several chloroanilines (CAs) as individual compounds or a mixture was isolated from a CA-degrading mixed bacterial culture. The isolated strain could completely degrade 3-CA and 4-CA as growth substrates, while concurrently metabolize 2-CA by growing on other CA compounds. The strain could also efficiently degrade all the three CA components when presented as a mixture. Following CA consumption, stoichiometric amounts of chloride were released and small amount of soluble metabolites accumulated in the medium, indicating that the loss of CA was mainly via mineralization and incorporation into cell material. The additions of yeast extract, citrate or succinate appeared to accelerate CA degradation. In contrast, aniline strongly inhibited the CA degradation. The strain H1 could also decompose other substituted aniline compounds such as 3,4-dichloroaniline, 4-methylaniline, 2,3-dichloroaniline and 2,4-dichloroaniline. The elimination of these CA compounds seemed to occur via an ortho-cleavage pathway.

Enantioselective hydrolysis of (R)-2, 2-dimethylcyclopropane carboxamide by immobilized cells of an R-amidase-producing bacterium, Delftia tsuruhatensis CCTCC M 205114, on an alginate capsule carrier.

Immobilized cells of Delftia tsuruhatensis CCTCC M 205114 harboring R-amidase were applied in asymmetric hydrolysis of (R)-2, 2-dimethylcyclopropane carboxamide (R - 1) from racemic (R, S)-2, 2-dimethylcyclopropane carboxamide to accumulate (S)-2, 2-dimethylcyclopropane carboxamide (S - 1). Maximum R-amidase activity of 13.1 U/g wet cells (0.982 U/g beads) was obtained under conditions of 3% sodium alginate, 2.5% CaCl(2), 15 h crosslinking and 2 mm bead size, which was 53.9% of that of free cells (24.3 U/g wet cells). In addition, characterization of the immobilized cells was examined. The optimum R - 1 hydrolysis conditions were identified as follows: substrate concentration 10 mM, pH 8.5, temperature 35 degrees C and time course 40 min. Under optimum conditions, the maximum yield and enantiomeric excess of (R)-2, 2-dimethylcyclopropanecarboxylic acid were 49.5% and >99%, respectively. This afforded S - 1 with a yield >49% and an e.e. of 97.7%. With good operational stability and excellent enanotioselectivity, the immobilized cells could be potentially utilized in industrial production of S - 1.

The catalytic mechanism of fluoroacetate dehalogenase: a computational exploration of biological dehalogenation.

The biological dehalogenation of fluoroacetate carried out by fluoroacetate dehalogenase is discussed by using quantum mechanical/molecular mechanical (QM/MM) calculations for a whole-enzyme model of 10 800 atoms. Substrate fluoroacetate is anchored by a hydrogen-bonding network with water molecules and the surrounding amino acid residues of Arg105, Arg108, His149, Trp150, and Tyr212 in the active site in a similar way to haloalkane dehalogenase. Asp104 is likely to act as a nucleophile to attack the alpha-carbon of fluoroacetate, resulting in the formation of an ester intermediate, which is subsequently hydrolyzed by the nucleophilic attack of a water molecule to the carbonyl carbon atom. The cleavage of the strong C-F bond is greatly facilitated by the hydrogen-bonding interactions between the leaving fluorine atom and the three amino acid residues of His149, Trp150, and Tyr212. The hydrolysis of the ester intermediate is initiated by a proton transfer from the water molecule to His271 and by the simultaneous nucleophilic attack of the water molecule. The transition state and produced tetrahedral intermediate are stabilized by Asp128 and the oxyanion hole composed of Phe34 and Arg105.

Improvement of amidase production by a newly isolated Delftia tsuruhatensis ZJB-05174 through optimization of culture medium.

The R-amidase production by a newly isolated strain of Delftia tsuruhatensis ZJB-05174 was optimized in this paper. Effects of factors such as carbon sources, nitrogen sources, and inducers on amidase production were investigated. The medium composition was optimized using central composite designs and response surface analysis. The optimal medium components for enhanced amidase production were found to be as follows: glucose, 8.23 g/l; yeast extract, 11.59 g/l; 2,2-(R,S)-dimethylcyclopropane carboxamide, 1.76 g/l; NaCl, 1 g/l; KH2PO4, 1 g/l; and K2HPO4, 1 g/l. A maximum enzyme production of 528.21 U/l was obtained under the optimized conditions, which was 4.7 times higher than that obtained under initial conditions.

Degradation of plasticizer di-n-butylphthalate by Delftia sp. TBKNP-05.

Bacterial strain Delftia sp. TBKNP-05, isolated by para-hydroxybenzoate enrichment technique, is capable of degrading di-n-butylphthalate (DBP) as a sole source of carbon and energy. Analysis of intermediates by thin-layer chromatography and high-performance liquid chromatography indicated the presence of monobutylphthalate (MBP), phthalate (PA), and protocatechuate (PCA). The washed cells grown on DBP and PA showed appreciable oxidation of DBP, MBP, PA, and PCA. The enzyme activities in cell-free extracts of Delftia sp. TBKNP-05 exhibited the presence of DBP esterase, MBP esterase, PA-dioxygenase, and PCA 4,5-dioxygenase. The PCA is metabolized by meta-cleavage pathway, leading to further mineralization of the compound in this bacterium.

Degradation of a Plasticizer, di-n-Butylphthalate by Delftia sp. TBKNP-05.

A bacterial strain Delftia sp. TBKNP-05 isolated by para-hydroxybenzoate enrichment technique is capable of degrading di-n-butylphthalate (DBP) as a sole source of carbon and energy. Analysis of intermediates by thin layer chromatography and high performance liquid chromatography indicated the presence of monobutylphthalate (MBP), phthalate (PA), and protocatechuate (PCA). The washed cells grown on DBP and PA showed appreciable oxidation of DBP, MBP, PA, and PCA. The enzyme activities in cell free extracts of Delftia sp. TBKNP-05 exhibited the presence of DBP esterase, MBP esterase, PA-dioxygenase, and protocatechuate 4, 5-dioxygenase. The protocatechuate is metabolized by a meta-cleavage pathway leading to further mineralization of the compound in this bacterium.