LCMS-Metabolomic Profiling and Genome Mining of Delftia lacustris DSM 21246 Revealed Lipophilic Delftibactin Metallophores.

Bacteria have evolved various strategies to combat heavy metal stress, including the secretion of small molecules, known as metallophores. These molecules hold a potential role in the mitigation of toxic metal contamination from the environment (bioremediation). Herein, we employed combined comparative metabolomic and genomic analyses to study the metallophores excreted by Delftia lacustris DSM 21246. LCMS-metabolomic analysis of this bacterium cultured under iron limitation led to a suite of lipophilic metallophores exclusively secreted in response to iron starvation. Additionally, we conducted genome sequencing of the DSM 21246 strain using nanopore sequencing technology and employed antiSMASH to mine the genome, leading to the identification of a biosynthetic gene cluster (BGC) matching the known BGC responsible for delftibactin A production. The isolated suite of amphiphilic metallophores, termed delftibactins C-F (1-4), was characterized using various chromatographic, spectroscopic, and bioinformatic techniques. The planar structure of these compounds was elucidated through 1D and 2D NMR analyses, as well as LCMS/MS-based fragmentation studies. Notably, their structures differed from previously known delftibactins due to the presence of a lipid tail. Marfey's and bioinformatic analyses were employed to determine the absolute configuration of the peptide scaffold. Delftibactin A, a previously identified metallophore, has exhibited a gold biomineralizing property; compound 1 was tested for and also demonstrated this property.

Characterization and Genome Analysis of the Delftia lacustris Strain LzhVag01 Isolated from Vaginal Discharge.

Delftia has been separated from freshwater, sludge, and soil and has emerged as a novel opportunistic pathogen in the female vagina. However, the genomic characteristics, pathogenicity, and biotechnological properties still need to be comprehensively investigated. In this study, a Delftia strain was isolated from the vaginal discharge of a 43-year-old female with histologically confirmed cervical intraepithelial neoplasm (CIN III), followed by whole-genome sequencing. Phylogenetic analysis and average nucleotide identity (ANI) analysis demonstrated that it belongs to Delftia lacustris, named D. lacustris strain LzhVag01. LzhVag01 was sensitive to ß-lactams, macrolides, and tetracyclines but exhibited resistance to lincoamines, nitroimidazoles, aminoglycosides, and fluoroquinolones. Its genome is a single, circular chromosome of 6,740,460 bp with an average GC content of 66.59%. Whole-genome analysis identified 16 antibiotic resistance-related genes, which match the antimicrobial susceptibility profile of this strain, and 11 potential virulence genes. These pathogenic factors may contribute to its colonization in the vaginal environment and its adaptation and accelerate the progression of cervical cancer. This study sequenced and characterized the whole-genome of Delftia lacustris isolated from vaginal discharge, which provides investigators and clinicians with valuable insights into this uncommon species.

Delftia tsuruhatensis, an Emergent Opportunistic Healthcare-Associated Pathogen.

Delftia tsuruhatensis, which was first isolated in environmental samples, was rarely associated with human infections. We report on pneumonia caused by D. tsuruhatensis in an infant who underwent cardiac surgery. Retrospective analyses detected 9 other isolates from 8 patients. D. tsuruhatensis is an emergent pathogen, at least for immunocompromised patients.

Delftia sp. LCW, a strain isolated from a constructed wetland shows novel properties for dimethylphenol isomers degradation.

BACKGROUND: Dimethylphenols (DMP) are toxic compounds with high environmental mobility in water and one of the main constituents of effluents from petro- and carbochemical industry. Over the last few decades, the use of constructed wetlands (CW) has been extended from domestic to industrial wastewater treatments, including petro-carbochemical effluents. In these systems, the main role during the transformation and mineralization of organic pollutants is played by microorganisms. Therefore, understanding the bacterial degradation processes of isolated strains from CWs is an important approach to further improvements of biodegradation processes in these treatment systems. RESULTS: In this study, bacterial isolation from a pilot scale constructed wetland fed with phenols led to the identification of Delftia sp. LCW as a DMP degrading strain. The strain was able to use the o-xylenols 3,4-DMP and 2,3-DMP as sole carbon and energy sources. In addition, 3,4-DMP provided as a co-substrate had an effect on the transformation of other four DMP isomers. Based on the detection of the genes, proteins, and the inferred phylogenetic relationships of the detected genes with other reported functional proteins, we found that the phenol hydroxylase of Delftia sp. LCW is induced by 3,4-DMP and it is responsible for the first oxidation of the aromatic ring of 3,4-, 2,3-, 2,4-, 2,5- and 3,5-DMP. The enzyme may also catalyze both monooxygenation reactions during the degradation of benzene. Proteome data led to the identification of catechol meta cleavage pathway enzymes during the growth on ortho DMP, and validated that cleavage of the aromatic rings of 2,5- and 3,5-DMPs does not result in mineralization. In addition, the tolerance of the strain to high concentrations of DMP, especially to 3,4-DMP was higher than that of other reported microorganisms from activated sludge treating phenols. CONCLUSIONS: LCW strain was able to degraded complex aromatics compounds. DMPs and benzene are reported for the first time to be degraded by a member of Delftia genus. In addition, LCW degraded DMPs with a first oxidation of the aromatic rings by a phenol hydroxylase, followed by a further meta cleavage pathway. The higher resistance to DMP toxicity, the ability to degrade and transform DMP isomers and the origin as a rhizosphere bacterium from wastewater systems, make LCW a suitable candidate to be used in bioremediation of complex DMP mixtures in CWs systems.

Biodegradation of diethyl terephthalate and polyethylene terephthalate by a novel identified degrader Delftia sp. WL-3 and its proposed metabolic pathway.

Polyethylene terephthalate (PET), a synthetic polyester material made of diethyl terephthalate (DET) monomers, is widely used in plastic products of daily life and caused serious pollution to the global environment. Microbial metabolism is the major degradation pathway responsible for DET degradation in natural soil; however, the microbial DET degradation mechanism remains unclear. In this study, the newly isolated strain WL-3, identified as belonging to the genus Delftia, was found to be able to degrade 94% of 5 g l-1 of DET and utilize it as the sole carbon source for growth within 7 days. Furthermore, strain WL-3 was capable of stable DET degradation under a wide range of pH values (6·0-9·0) and temperatures (20-42°C) with the optimal pH and temperature of 7·0 and 30°C respectively. Furthermore, the biochemical pathway of DET degradation by strain WL-3 was proposed based on the identified degradation intermediates. DET is first transformed into terephthalic acid (TPA) by the hydrolysis of two ester bonds, which is subsequently converted to protocatechuic acid (PCA) and further mineralized. SEM observations revealed obvious cracks on the surface of PET film after inoculation of 2 months with strain WL-3, indicating the strain's potential for the bioremediation of PET-contaminated environments. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates that Delftia sp. WL-3 can mineralize completely diethyl terephthalate by biochemical processes. The study reveals the metabolic mechanism of diethyl terephthalate biodegradation. Furthermore, the cracks on the surface of Polyethylene terephthalate film that form upon inoculation with strain WL-3 were observed using SEM. These results highlight the potential of the strain WL-3 in the bioremediation of environments contaminated with Polyethylene terephthalate or diethyl terephthalate.

Delftia rhizosphaerae sp. nov. isolated from the rhizosphere of Cistus ladanifer.

A bacterial strain, designated RA6T, was isolated from the rhizosphere of Cistus ladanifer. Phylogenetic analyses based on 16S rRNA gene sequence placed the isolate into the genus Delftia within a cluster encompassing the type strains of Delftia lacustris, Delftia tsuruhatensis, Delftia acidovorans and Delftia litopenaei, which presented greater than 97 % sequence similarity with respect to strain RA6T. DNA-DNA hybridization studies showed average relatedness ranging from of 11 to 18 % between these species of the genus Delftia and strain RA6T. Catalase and oxidase were positive. Casein was hydrolysed but gelatin and starch were not. Ubiquinone 8 was the major respiratory quinone detected in strain RA6T together with low amounts of ubiquinones 7 and 9. The major fatty acids were those from summed feature 3 (C16 : 1ω7c/C16 : 1 ω6c) and C16 : 0. The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Phylogenetic, chemotaxonomic and phenotypic analyses showed that strain RA6T should be considered as a representative of a novel species of genus Delftia, for which the name Delftia rhizosphaerae sp. nov. is proposed. The type strain is RA6T (=LMG 29737T= CECT 9171T).

Genome sequencing reveals mechanisms for heavy metal resistance and polycyclic aromatic hydrocarbon degradation in Delftia lacustris strain LZ-C.

Strain LZ-C, isolated from a petrochemical wastewater discharge site, was found to be resistant to heavy metals and to degrade various aromatic compounds, including naphenol, naphthalene, 2-methylnaphthalene and toluene. Data obtained from 16S rRNA gene sequencing showed that this strain was closely related to Delftia lacustris. The 5,889,360 bp genome of strain LZ-C was assembled into 239 contigs and 197 scaffolds containing 5855 predicted open reading frames (ORFs). Among these predicted ORFs, 464 were different from the type strain of Delftia. The minimal inhibitory concentrations were 4 mM, 30 µM, 2 mM and 1 mM for Cr(VI), Hg(II), Cd(II) and Pb(II), respectively. Both genome sequencing and quantitative real-time PCR data revealed that genes related to Chr, Czc and Mer family genes play important roles in heavy metal resistance in strain LZ-C. In addition, the Na(+)/H(+) antiporter NhaA is important for adaptation to high salinity resistance (2.5 M NaCl). The complete pathways of benzene and benzoate degradation were identified through KEGG analysis. Interestingly, strain LZ-C also degrades naphthalene but lacks the key naphthalene degradation gene NahA. Thus, we propose that strain LZ-C exhibits a novel protein with a function similar to NahA. This study is the first to reveal the mechanisms of heavy metal resistance and salinity tolerance in D. lacustris and to identify a potential 2-methylnaphthalene degradation protein in this strain. Through whole-genome sequencing analysis, strain LZ-C might be a good candidate for the bioremediation of heavy metals and polycyclic aromatic hydrocarbons.

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.

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.

Delftia deserti sp. nov., isolated from a desert soil sample.

A Gram-staining negative, short rod, motile, light brownish-pigmented bacterial strain, designated YIM Y792(T), was isolated from a soil sample taken from Turpan desert in Xinjiang Uyghur Autonomous Region, north-western China. Phylogenetic analysis indicated that strain YIM Y792(T) belongs to the genus Delftia. Strain YIM Y792(T) shared highest 16S rRNA gene sequence similarities with Delftia lacustris DSM 21246(T) (93.96 %), Delftia tsuruhatensis NBRC 16741(T) (93.74 %), and Delftia acidovorans NBRC 14950(T) (93.62 %). Growth of the strain YIM Y792(T) was found to occur at 20-45 °C (optimum at 30 °C), pH 6.0-9.0 (optimum at pH 7.0), and salinities of 0-3.0 % NaCl (optimum at 1.0 %). The new bacterium exhibits typical chemotaxonomic features of the genus Delftia with ubiqinone-8 (Q-8) as the predominant quinone and C16:0, Summed feature 3, Summed Feature 8 as major fatty acids (>10 %). The polar lipids were found to consist of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, glycolipid, two unidentified phospholipids and one unidentified lipid. The G+C content of the genomic DNA of strain YIM Y792(T) was found to be 70.3 mol%. The DNA-DNA relatedness values between strain YIM Y792(T) and D. lacustris DSM 21246(T), D. tsuruhatensis NBRC16741(T), D. acidovorans NBRC14950(T) were 35.5 ± 2.0, 17.1 ± 1.8, 26.2 ± 2.0 %. Based on the phylogenetic, chemotaxonomic and phenotypic data presented here, we propose a novel species with the name Delftia desertisoli sp. nov. The type strain is YIM Y792(T) (=KCTC 42377(T) = JCM 30639(T)).

Characterization and Genomic Analysis of Quinolone-Resistant Delftia sp. 670 Isolated from a Patient Who Died from Severe Pneumonia.

Antibiotic-resistant opportunistic pathogens have become a serious concern in recent decades, as they are increasingly responsible for hospital-acquired infections. Here, we describe quinolone-resistant Delftia sp. strain 670, isolated from the sputum of a patient who died from severe pulmonary infection. The draft genome sequence of this strain was obtained by whole-genome shotgun sequencing, and was subjected to comparative genome analysis. Genome analysis revealed that one critical mutation (Ser83Ile in gyrA) might play a decisive role in quinolone resistance. The genome of Delftia sp. strain 670 contains both type II and type VI secretion systems, which were predicted to contribute to the virulence of the strain. Phylogenetic analysis, assimilation tests, and comparative genome analysis indicated that strain 670 differed from the four known Delftia species, suggesting this strain could represent a novel species. Although the study could not determine the strain 670 as the pathogen led to mortality, our findings also presented the pathogenic potential of Delftia species, and the increasing severity of antibiotic resistance among emerging opportunistic pathogens. The whole genome sequencing and comparative analysis improved our understanding of genome evolution in the genus Delftia, and provides the foundation for further study on drug resistance and virulence of Delftia strains.

Delftia tsuruhatensis WGR-UOM-BT1, a novel rhizobacterium with PGPR properties from Rauwolfia serpentina (L.) Benth. ex Kurz also suppresses fungal phytopathogens by producing a new antibiotic-AMTM.

UNLABELLED: The bacterial strain designated as WGR-UOM-BT1 isolated from rhizosphere of Rauwolfia serpentina exhibited broad-spectrum antifungal activity and also improved early plant growth. Based on morphological, biochemical and 16S rRNA gene sequence analyses, the strain BT1 was identified as Delftia tsuruhatensis (KF727978). Under in vitro conditions, the strain BT1 suppressed the growth of wide range of fungal phytopathogens. Purified antimicrobial metabolite from the strain BT1 was identified as nitrogen-containing heterocyclic compound, 'amino(5-(4-methoxyphenyl)-2-methyl-2-(thiophen-2-yl)-2,3-dihydrofuran-3-yl)methanol' (AMTM), with molecular mass of 340•40 and molecular formula of C17 H19 NO3 S. The strain BT1 was positive for rhizosphere colonization (tomato), IAA production, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity and phosphate solubilization. Under laboratory and greenhouse conditions, the strain BT1 promoted plant growth and suppressed foliar and root fungal pathogens of tomato. Therefore, antimicrobial and disease protection properties of strain BT1 could serve as an effective biological control candidate against devastating fungal pathogens of vegetable plants. Besides, the production of IAA, P solubilization and ACC deaminase activity enhance its potential as a biofertilizer and may stabilize the plant performance under fluctuating environmental conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, we reported that Delftia tsuruhatensis WGR-UOM-BT1 strain has the plant growth promotion activities such as rhizosphere colonization (tomato), IAA production, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity and phosphate solubilization. This bacterial strain was found producing an antimicrobial nitrogen-containing heterocyclic compound identified as 'amino(5-(4-methoxyphenyl)-2-methyl-2-(thiophen-2-yl)-2,3-dihydrofuran-3-yl)methanol' [C17 H19 NO3 S] (AMTM), which is new to the bacterial world.

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.

Complete biodegradation of fungicide carboxin and its metabolite aniline by Delftia sp. HFL-1.

Fungicide carboxin was commonly used in the form of seed coating for the prevention of smut, wheat rust and cotton damping-off, leading carboxin and its probable carcinogenic metabolite aniline to directly enter the soil with the seeds, causing residual pollution. In this study, a novel carboxin degrading strain, Delftia sp. HFL-1, was isolated. Strain HFL-1 could use carboxin as the carbon source for growth and completely degrade 50 mg/L carboxin and its metabolite aniline within 24 h. The optimal temperatures and pH for carboxin degrading by strain HFL-1 were 30 to 42 °C and 5 to 9, respectively. Furthermore, the complete mineralization pathway of carboxin by strain HFL-1 was revealed by High Resolution Mass Spectrometer (HRMS). Carboxin was firstly hydrolyzed into aniline and further metabolized into catechol through multiple oxidation processes, and finally converted into 4-hydroxy-2-oxopentanoate, a precursor of the tricarboxylic acid cycle. Genome sequencing revealed the corresponding degradation genes and cluster of carboxin. Among them, amidohydrolase and dioxygenase were key enzymes involved in the degradation of carboxin and aniline. The discovery of transposons indicated that the aniline degradation gene cluster in strain HFL-1 was obtained via horizontal transfer. Furthermore, the degradation genes were cloned and overexpressed. The in vitro test showed that the expressed degrading enzyme could efficiently degrade aniline. This study provides an efficient strain resource for the bioremediation of carboxin and aniline in contaminated soil, and further revealing the molecular mechanism of biodegradation of carboxin and aniline.

Port-related Delftia tsuruhatensis bacteremia in a patient with breast cancer.

Delftia tsuruhatensis is a non-glucose fermenting, oxidase positive, motile, gram-negative bacillus first isolated from activated sludge collected from a domestic wastewater treatment plant in Japan. To the best of our knowledge only one case of infection with Delftia tsuruhatensis exists in the medical literature. This is the second case report of human infection having Delftia tsuruhatensis as a causative agent.

IncP-1ß plasmids of Comamonas sp. and Delftia sp. strains isolated from a wastewater treatment plant mediate resistance to and decolorization of the triphenylmethane dye crystal violet.

The application of toxic triphenylmethane dyes such as crystal violet (CV) in various industrial processes leads to large amounts of dye-contaminated sludges that need to be detoxified. Specific bacteria residing in wastewater treatment plants (WWTPs) are able to degrade triphenylmethane dyes. The objective of this work was to gain insights into the genetic background of bacterial strains capable of CV degradation. Three bacterial strains isolated from a municipal WWTP harboured IncP-1ß plasmids mediating resistance to and decolorization of CV. These isolates were assigned to the genera Comamonas and Delftia. The CV-resistance plasmid pKV29 from Delftia sp. KV29 was completely sequenced. In addition, nucleotide sequences of the accessory regions involved in conferring CV resistance were determined for plasmids pKV11 and pKV36 from the other two isolates. Plasmid pKV29 contains typical IncP-1ß backbone modules that are highly similar to those of previously sequenced IncP-1ß plasmids that confer antibiotic resistance, degradative capabilities or mercury resistance. The accessory regions located between the conjugative transfer (tra) and mating pair formation modules (trb) of all three plasmids analysed share common modules and include a triphenylmethane reductase gene, tmr, that is responsible for decolorization of CV. Moreover, these accessory regions encode other enzymes that are dispensable for CV degradation and hence are involved in so-far-unknown metabolic pathways. Analysis of plasmid-mediated degradation of CV in Escherichia coli by ultra-high-performance liquid chromatography-electrospray ionization-quadrupole-time-of-flight MS revealed that leuco crystal violet was the first degradation product. Michler's ketone and 4-dimethylaminobenzaldehyde appeared as secondary degradation metabolites. Enzymes encoded in the E. coli chromosome seem to be responsible for cleavage of leuco crystal violet. Plasmid-mediated degradation of triphenylmethane dyes such as CV is an option for the biotechnological treatment of sludges contaminated with these dyes.

Delftia litopenaei sp. nov., a poly-ß-hydroxybutyrate-accumulating bacterium isolated from a freshwater shrimp culture pond.

A Gram-negative, short-rod-shaped, motile, non-spore-forming and poly-ß-hydroxybutyrate-accumulating bacterial strain, designated wsw-7(T), was isolated from a freshwater shrimp culture pond in Taiwan and was characterized using a polyphasic taxonomic approach. Phylogenetic analyses based on 16S rRNA gene sequences showed that the closest relatives of strain wsw-7(T) were Delftia lacustris 332(T), Delftia tsuruhatensis T7(T) and Delftia acidovorans ATCC 15668(T), with sequence similarities of 98.5, 98.4 and 97.9%, respectively. Phylogenetic trees obtained with 16S rRNA gene sequences or the polyhydroxyalkanoate synthase (phaC) gene sequences revealed that strain wsw-7(T) and these three closest relatives formed an independent phylogenetic clade within the order Burkholderiales. Strain wsw-7(T) contained summed feature 3 (comprising C(16:1)ω7c and/or C(16:1)ω6c), C(18:0) and C(18:1)ω7c as predominant fatty acids. The major isoprenoid quinone was Q-8 and the DNA G+C content was 67.6 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, an uncharacterized aminolipid and several uncharacterized phospholipids. On the basis of the genotypic, chemotaxonomic and phenotypic data, strain wsw-7(T) represents a novel species in the genus Delftia, for which the name Delftia litopenaei sp. nov. is proposed; the type strain is wsw-7(T) ( = BCRC 80212(T) = LMG 25724(T)).

Four cases of possible human infections with Delftia lacustris.

We report four cases of possible human infections with Delftia lacustris. D. lacustris isolates, which were isolated from blood cultures and bile fluid of patients with underlying diseases such as empyema, renal injury, hepatocellular carcinoma, and renal infarction, were identified using 16S rRNA gene sequencing and biochemical tests. Four D. lacustris isolates did not show the same antimicrobial susceptibility profiles and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) patterns, indicating their non-clonality.

The versatility of Delftia sp. isolates as tools for bioremediation and biofertilization technologies.

Two Pb(II)-resistant bacteria isolated from a soil containing 2,500 mg/kg of Pb were identified by 16S rRNA sequencing analysis as Delftia sp. and designated as 3C and 6C. Both isolates grew at a Pb(II) concentration of 62 mg/L and at the stationary phase showed a Pb(II)-sorption capability of 10 ± 1.5 (3C) and 5 ± 0.8 (6C) mg/g of biomass. Biochemical properties related to heavy metal resistance and plant growth promotion were analyzed and compared with the Cr(VI)-resistant plant growth-promoting Delftia sp. JD2, previously reported by our group. Both isolates and JD2 were resistant to Cr(VI), Pb(II) and many antibiotics, produced siderophores and the phytohormone indole-3-acetic, and showed clover growth-promoting activity in greenhouse conditions. Interestingly, the occurrence of integron class 1 was shown in all isolates. Our results add to previous reports and suggest that bacteria of the genus Delftia could be consider as good candidates for the design of technologies for cleaning up contaminated environments and/or the production of biofertilizers.

Phylogenomic analysis of the genus Delftia reveals distinct major lineages with ecological specializations.

Delftia is a diverse betaproteobacterial genus with many strains having agricultural and industrial relevance, including plant-growth promotion, bioremediation of hydrocarbon-contaminated soils, and heavy metal immobilization. Delftia spp. are broadly distributed in the environment, and have been isolated from plant hosts as well as healthy and diseased animal hosts, yet the genetic basis of this ecological versatility has not been characterized. Here, we present a phylogenomic comparison of published Delftia genomes and show that the genus is divided into two well-supported clades: one 'Delftia acidovorans' clade with isolates from soils and plant rhizospheres, and a second 'Delftia lacustris and Delftia tsuruhatensis' clade with isolates from humans and sludge. The pan-genome inferred from 61 Delftia genomes contained over 28 000 genes, of which only 884 were found in all genomes. Analysis of industrially relevant functions highlighted the ecological versatility of Delftia and supported their role as generalists.