A recombinant strain, Escherichia coli JM109-AN1, was obtained by constructing of a genomic library of the total DNA of Delftia sp. AN3 in E. coli JM109 and screening for catechol 2,3-dioxygenase activity. This recomb...A recombinant strain, Escherichia coli JM109-AN1, was obtained by constructing of a genomic library of the total DNA of Delftia sp. AN3 in E. coli JM109 and screening for catechol 2,3-dioxygenase activity. This recombinant strain could grow on aniline as sole carbon, nitrogen and energy source. Enzymatic assays revealed that the exogenous genes including aniline dioxygenase （AD） and catechol 2,3-dioxygenase （C230） genes could well express in the recombinant strain with the activities of AD and C230 up to 0.31 U/mg wet cell and 1.92 U/mg crude proteins, respectively. The AD or C23O of strain AN3 could only catalyze aniline or catechol but not any other substituted substrates. This recombinant strain contained a recombinant plasmid, pKC505-AN1, in which a 29.7-kb DNA fragment from Delftia sp. AN3 was inserted. Sequencing and open reading frame （orfs） analysis of this 29.7 kb fragment revealed that it contained at least 27 orfs, among them a gene cluster （consisting of at least 16 genes, named danQTA1A2BRDCEFG1HIJKG2） was responsible for the complete metabolism of aniline to TCA-cycle intermediates. This gene cluster could be divided into two main parts, the upper sequences consisted of 7 genes （danQTA1A2BRD） were predicted to encode a multi-component aniline dioxygenase and a LysR-type regulator, and the central genes （danCEFG1HIJKG2） were expected to encode meta-cleavage pathway enzymes for catechol degradation to TCA-cycle intermediates. Unlike clusters tad from Delftia tsuruhatensis AD9 and tdn from Pseudomonas putida UCC22, in this gene cluster, all the genes were in the same transcriptional direction. There was only one set of C230 gene （danC） and ferredoxin-like protein gene （danD）. The presence of only one set of these two genes and specificity of AD and C230 might be the reason for strain AN3 could only degrade aniline. The products of danQTA1A2BRDC showed 99%-100% identity to those from Delftia acidovorans 7N, and 50%-85% identity to those of tad cluster from D. tsuruhatensis AD9 in amino acid residues. Besides this dan cluster, the 29.7 kb fragment also contained genes encoding the trans-membrane transporter and transposases which might be needed for transposition of the gene cluster. Pulsed-field gel electrophoresis （PFGE） and plasmid curing experiments suggested that the dan cluster might be encoded on the chromosome of strain AN3. The GenBank accession number for the dan cluster of Delftia sp. AN3 is DQ661649.展开更多
Delftia acidovorans(earlier known as Comamonas acidovorans) is an aerobic,non-fermentative, Cram negative rod,classified in the Pseudomonas rRNA homology Group 111.Reports of isolation of the organism from serious inf...Delftia acidovorans(earlier known as Comamonas acidovorans) is an aerobic,non-fermentative, Cram negative rod,classified in the Pseudomonas rRNA homology Group 111.Reports of isolation of the organism from serious infections like central venoug catheter associated bacleremia. corneal ulcers,otitis media exist.The microbiologists can identify this organism based on an orange indole reaction.This reaction demonstrates the organism's ability to produce anthranilic acid from tryptophan on addition of Kovac's reagent;which gives the media its characteristic "pumpkin orange" colour.Here we report the isolation of this organism from the Endotracheal tube aspirate of a 4 year old child.With the increasing use of invasive devices,it has become important to recognize these non fermentative gram negative bacilli as emerging source of infection even in immunocompetent individuals.展开更多
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 i...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.展开更多
A bacterial strain capable of Zinc and Lead biosorption was isolated from mine tailings. This strain showed the highest minimum inhibitory concentrations (MIC) of metals among other isolates in metal-resistance tests....A bacterial strain capable of Zinc and Lead biosorption was isolated from mine tailings. This strain showed the highest minimum inhibitory concentrations (MIC) of metals among other isolates in metal-resistance tests. Sorption tests were conducted placing 0.015 g of dry biomass in 10 ml of metallic solution at fixed pH. Contact was analyzed at different times (kinetics) and different initial concentrations (isotherm). The biomass was separated by centrifugation and the concentration of non-absorbed metal was determined using atomic absorption spectroscopy. The strain was identified by 16S sequencing as Delftia tsuruhatensis. The order of toxicity of the metals to the bacterium was Zn > Pb > Se > Ni > Cu = Al. Zinc and Lead absorption kinetics were adjusted to the pseudo second order equation (r2 = 0.99), showing that equilibrium was reached at 40 and 20 min, respectively. Maximal absorption of Pb and Zn was 0.216 and 0.207 mmol?g–1, respectively;which can be considered a median magnitude capacity when compared to other biosorbents described in the literature.展开更多
A promising gram-negative bacterial strain for the biodegradation of aniline as the sole carbon, nitrogen and energy sources was successfully isolated and identified as Delftia sp. XYJ6. The optimal temperature and pH...A promising gram-negative bacterial strain for the biodegradation of aniline as the sole carbon, nitrogen and energy sources was successfully isolated and identified as Delftia sp. XYJ6. The optimal temperature and pH for both the growth of Delftia sp. XYJ6 and the biodegradation of aniline were 30°C and 7.0, respectively. Initial aniline of 2000 mg·L-1 could be completely removed by the strain at 22 h, which showed that Delftia sp. XYJ6 had a strong ability in the biodegradation of aniline. It indicated that aniline was firstly converted to catechol catalyzed by aniline dioxygenase as a first product, which was then further biodegraded to cis,cis-muconic acid catalyzed by the catechol 1,2-dioxygenase of Delftia sp. XYJ6 as a second product. Cis,cis-muconic acid could also be further biodegraded to other small compound again. The pathway for the biodegradation of aniline by Delftia sp. XYJ6 was not previously reported.展开更多
Per-and Polyfluorinated alkyl substances(PFAS)are a broad class of synthetic compounds that have fluorine substituted for hydrogen in several or all locations and are globally categorized as PFCs(perfluorochemicals;co...Per-and Polyfluorinated alkyl substances(PFAS)are a broad class of synthetic compounds that have fluorine substituted for hydrogen in several or all locations and are globally categorized as PFCs(perfluorochemicals;commonly called fluorinated chemicals).These compounds have unique chemical and physical properties that enable their use in non-stick surfaces,fire-fighting efforts,and as slick coatings.However,recent concerns over the health effects of such compounds,specifically perfluorooctanoic acid and perfluorooctane sulfonic acid(PFOA,PFOS;PFOA/S),have led to increased attention and research by the global community into degradation methods.In this study,soil samples from PFAS-contamination sites were cultured and screened for microbes with PFOA/S degradation potential,which led to the identification of Delftia acidovorans.It was found that D.acidovorans isolated from PFAS-contaminated soils was capable of growth in minimal media with PFOA as a sole carbon resource,and an observable fluoride concentration increase was observed when cells were exposed to PFOA.This suggests potential activity of a dehalogenase enzyme that may be of use in PFOA or PFAS microbial remediation efforts.Several associated haloacid dehalogenases have been identified in the D.acidovorans genome and have been engineered for expression in Escherichia coli for rapid production and purification.These enzymes have shown potential for enzymatic defluorination,a significant step in biological degradation and removal of PFOA/S from the environment.We hypothesize that bioremediation of PFAS using naturally occurring microbial degradation pathways may represent a novel approach to remove PFAS contamination.展开更多
Salinity is a major environmental stress affecting crop growth and productivity globally.The application of halotolerant plant growth-promoting bacteria(HT-PGPB)has been widely recognized to promote crop growth and re...Salinity is a major environmental stress affecting crop growth and productivity globally.The application of halotolerant plant growth-promoting bacteria(HT-PGPB)has been widely recognized to promote crop growth and reduce the adverse effects of salt stress.In this study,key endophytic bacteria that can respond to salinity changes were identified by analyzing the microbial community in propagules of Kandelia obovata.Delftia tsuruhatensis DYX29,a strain that can grow normally under high salinity conditions with a sodium chloride(NaCl)concentration of 5%(w/v),was obtained by pure culture.DYX29 can produce siderophores with a siderophore unit value of 87.6%and 1-aminocyclopropane-1-carboxylate(ACC)deaminase with 29 UL^(-1),and its synthesis of intracellular amino acids and auxin can be induced by high salinity.Inoculation with DYX29 can remarkably promote the salt tolerance of rice.Under salt stress,the addition of DYX29 was shown to effectively promote the growth of rice seedlings through a variety of approaches.It increased the biomass of rice seedlings by 32.9%(dry weight)and promoted the accumulation of soluble sugars by 23.1%.It also increased catalase(CAT)and peroxidase(POD)activities in rice leaves by 37.8 and 88.2%,respectively.Moreover,it maintained the ionic homeostasis in rice roots and leaves.In addition,it upregulated the expression of growth-promoting hormones,such as indole-3-acetic acid(IAA),brassinolide(BL),abscisic acid(ABA),and salicylic acid(SA),in rice roots by 27.8,69.5,123.7 and 28.6%,respectively.This study provides inspiration for screening valuable salt-tolerant pro-biotic bacteria from mangrove ecosystems and their use for crop growth promotion under salt stress.It can also provide useful references for the development of new salt-tolerant and pro-biotic biofertilizers,as well as the investigation of the related mechanisms.展开更多
文摘A recombinant strain, Escherichia coli JM109-AN1, was obtained by constructing of a genomic library of the total DNA of Delftia sp. AN3 in E. coli JM109 and screening for catechol 2,3-dioxygenase activity. This recombinant strain could grow on aniline as sole carbon, nitrogen and energy source. Enzymatic assays revealed that the exogenous genes including aniline dioxygenase （AD） and catechol 2,3-dioxygenase （C230） genes could well express in the recombinant strain with the activities of AD and C230 up to 0.31 U/mg wet cell and 1.92 U/mg crude proteins, respectively. The AD or C23O of strain AN3 could only catalyze aniline or catechol but not any other substituted substrates. This recombinant strain contained a recombinant plasmid, pKC505-AN1, in which a 29.7-kb DNA fragment from Delftia sp. AN3 was inserted. Sequencing and open reading frame （orfs） analysis of this 29.7 kb fragment revealed that it contained at least 27 orfs, among them a gene cluster （consisting of at least 16 genes, named danQTA1A2BRDCEFG1HIJKG2） was responsible for the complete metabolism of aniline to TCA-cycle intermediates. This gene cluster could be divided into two main parts, the upper sequences consisted of 7 genes （danQTA1A2BRD） were predicted to encode a multi-component aniline dioxygenase and a LysR-type regulator, and the central genes （danCEFG1HIJKG2） were expected to encode meta-cleavage pathway enzymes for catechol degradation to TCA-cycle intermediates. Unlike clusters tad from Delftia tsuruhatensis AD9 and tdn from Pseudomonas putida UCC22, in this gene cluster, all the genes were in the same transcriptional direction. There was only one set of C230 gene （danC） and ferredoxin-like protein gene （danD）. The presence of only one set of these two genes and specificity of AD and C230 might be the reason for strain AN3 could only degrade aniline. The products of danQTA1A2BRDC showed 99%-100% identity to those from Delftia acidovorans 7N, and 50%-85% identity to those of tad cluster from D. tsuruhatensis AD9 in amino acid residues. Besides this dan cluster, the 29.7 kb fragment also contained genes encoding the trans-membrane transporter and transposases which might be needed for transposition of the gene cluster. Pulsed-field gel electrophoresis （PFGE） and plasmid curing experiments suggested that the dan cluster might be encoded on the chromosome of strain AN3. The GenBank accession number for the dan cluster of Delftia sp. AN3 is DQ661649.
文摘Delftia acidovorans(earlier known as Comamonas acidovorans) is an aerobic,non-fermentative, Cram negative rod,classified in the Pseudomonas rRNA homology Group 111.Reports of isolation of the organism from serious infections like central venoug catheter associated bacleremia. corneal ulcers,otitis media exist.The microbiologists can identify this organism based on an orange indole reaction.This reaction demonstrates the organism's ability to produce anthranilic acid from tryptophan on addition of Kovac's reagent;which gives the media its characteristic "pumpkin orange" colour.Here we report the isolation of this organism from the Endotracheal tube aspirate of a 4 year old child.With the increasing use of invasive devices,it has become important to recognize these non fermentative gram negative bacilli as emerging source of infection even in immunocompetent individuals.
基金supported by the National Natural Science Foundation of China (No. 203777008)the State Key Joint Laboratory of Environment Simulation and Pollution Control (No. 09K08ESPCT)the Fundamental Research Funds for the Central Universities (FRF-AS-10-001B)
文摘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.
文摘A bacterial strain capable of Zinc and Lead biosorption was isolated from mine tailings. This strain showed the highest minimum inhibitory concentrations (MIC) of metals among other isolates in metal-resistance tests. Sorption tests were conducted placing 0.015 g of dry biomass in 10 ml of metallic solution at fixed pH. Contact was analyzed at different times (kinetics) and different initial concentrations (isotherm). The biomass was separated by centrifugation and the concentration of non-absorbed metal was determined using atomic absorption spectroscopy. The strain was identified by 16S sequencing as Delftia tsuruhatensis. The order of toxicity of the metals to the bacterium was Zn > Pb > Se > Ni > Cu = Al. Zinc and Lead absorption kinetics were adjusted to the pseudo second order equation (r2 = 0.99), showing that equilibrium was reached at 40 and 20 min, respectively. Maximal absorption of Pb and Zn was 0.216 and 0.207 mmol?g–1, respectively;which can be considered a median magnitude capacity when compared to other biosorbents described in the literature.
基金Supported by the National Natural Science Foundation of China (20777008)the Education Committee of Beijing
文摘A promising gram-negative bacterial strain for the biodegradation of aniline as the sole carbon, nitrogen and energy sources was successfully isolated and identified as Delftia sp. XYJ6. The optimal temperature and pH for both the growth of Delftia sp. XYJ6 and the biodegradation of aniline were 30°C and 7.0, respectively. Initial aniline of 2000 mg·L-1 could be completely removed by the strain at 22 h, which showed that Delftia sp. XYJ6 had a strong ability in the biodegradation of aniline. It indicated that aniline was firstly converted to catechol catalyzed by aniline dioxygenase as a first product, which was then further biodegraded to cis,cis-muconic acid catalyzed by the catechol 1,2-dioxygenase of Delftia sp. XYJ6 as a second product. Cis,cis-muconic acid could also be further biodegraded to other small compound again. The pathway for the biodegradation of aniline by Delftia sp. XYJ6 was not previously reported.
文摘Per-and Polyfluorinated alkyl substances(PFAS)are a broad class of synthetic compounds that have fluorine substituted for hydrogen in several or all locations and are globally categorized as PFCs(perfluorochemicals;commonly called fluorinated chemicals).These compounds have unique chemical and physical properties that enable their use in non-stick surfaces,fire-fighting efforts,and as slick coatings.However,recent concerns over the health effects of such compounds,specifically perfluorooctanoic acid and perfluorooctane sulfonic acid(PFOA,PFOS;PFOA/S),have led to increased attention and research by the global community into degradation methods.In this study,soil samples from PFAS-contamination sites were cultured and screened for microbes with PFOA/S degradation potential,which led to the identification of Delftia acidovorans.It was found that D.acidovorans isolated from PFAS-contaminated soils was capable of growth in minimal media with PFOA as a sole carbon resource,and an observable fluoride concentration increase was observed when cells were exposed to PFOA.This suggests potential activity of a dehalogenase enzyme that may be of use in PFOA or PFAS microbial remediation efforts.Several associated haloacid dehalogenases have been identified in the D.acidovorans genome and have been engineered for expression in Escherichia coli for rapid production and purification.These enzymes have shown potential for enzymatic defluorination,a significant step in biological degradation and removal of PFOA/S from the environment.We hypothesize that bioremediation of PFAS using naturally occurring microbial degradation pathways may represent a novel approach to remove PFAS contamination.
基金supported by funds from the National Natural Science Foundation of China(32270296)the Natural Science Foundation of Guangdong Province,China(2024A1515010498)+1 种基金the Shenzhen Postdoctoral Scientific Research,China(77000-42100004)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University,China。
文摘Salinity is a major environmental stress affecting crop growth and productivity globally.The application of halotolerant plant growth-promoting bacteria(HT-PGPB)has been widely recognized to promote crop growth and reduce the adverse effects of salt stress.In this study,key endophytic bacteria that can respond to salinity changes were identified by analyzing the microbial community in propagules of Kandelia obovata.Delftia tsuruhatensis DYX29,a strain that can grow normally under high salinity conditions with a sodium chloride(NaCl)concentration of 5%(w/v),was obtained by pure culture.DYX29 can produce siderophores with a siderophore unit value of 87.6%and 1-aminocyclopropane-1-carboxylate(ACC)deaminase with 29 UL^(-1),and its synthesis of intracellular amino acids and auxin can be induced by high salinity.Inoculation with DYX29 can remarkably promote the salt tolerance of rice.Under salt stress,the addition of DYX29 was shown to effectively promote the growth of rice seedlings through a variety of approaches.It increased the biomass of rice seedlings by 32.9%(dry weight)and promoted the accumulation of soluble sugars by 23.1%.It also increased catalase(CAT)and peroxidase(POD)activities in rice leaves by 37.8 and 88.2%,respectively.Moreover,it maintained the ionic homeostasis in rice roots and leaves.In addition,it upregulated the expression of growth-promoting hormones,such as indole-3-acetic acid(IAA),brassinolide(BL),abscisic acid(ABA),and salicylic acid(SA),in rice roots by 27.8,69.5,123.7 and 28.6%,respectively.This study provides inspiration for screening valuable salt-tolerant pro-biotic bacteria from mangrove ecosystems and their use for crop growth promotion under salt stress.It can also provide useful references for the development of new salt-tolerant and pro-biotic biofertilizers,as well as the investigation of the related mechanisms.
