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
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
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
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
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
针对超高温灭菌(ultra-high temperature treated,UHT)乳在货架期内出现的脂肪上浮、水乳分离、沉淀等品质劣变问题,利用高通量测序和生物信息学等技术方法,对大型乳企采集的9份在货架期内品质劣变的UHT乳和正常质量的UHT乳样品的理化...针对超高温灭菌(ultra-high temperature treated,UHT)乳在货架期内出现的脂肪上浮、水乳分离、沉淀等品质劣变问题,利用高通量测序和生物信息学等技术方法,对大型乳企采集的9份在货架期内品质劣变的UHT乳和正常质量的UHT乳样品的理化指标、酶活性、微生物菌群进行了分析比较,并通过关联分析解析UHT灭菌乳品质劣变的关联微生物。结果表明:品质劣变UHT乳在理化指标、酶活性和微生物群分布方面与正常UHT乳有明显不同,假单胞杆菌、不动杆菌为品质劣变UHT乳中核心功能微生物且均属于常见的嗜冷菌,能够产生耐热酶,这可能是导致UHT乳腐败变质的主要原因。本研究为进一步解决UHT乳品质劣变问题提供了参考。展开更多
通过传统的分离方法和室内培养实验,从Cd污染土壤中筛选和分离出一株对Cd2+吸附率高的菌株B9,并分析B9对土壤Cd形态的影响,探究其在Cd污染土壤修复中应用的可行性。16S r RNA序列分析结果表明,B9与食酸代尔福特菌(Delftia acidovorans,...通过传统的分离方法和室内培养实验,从Cd污染土壤中筛选和分离出一株对Cd2+吸附率高的菌株B9,并分析B9对土壤Cd形态的影响,探究其在Cd污染土壤修复中应用的可行性。16S r RNA序列分析结果表明,B9与食酸代尔福特菌(Delftia acidovorans,登录号NC010002)的16S r RNA序列具有99%的同源性,结合形态和生理生化指标,将其鉴定为代尔福特菌。研究结果表明,B9在pH=8、温度为35℃、培养时间为48 h时,对Cd2+的吸附效果最好,且Cd2+浓度低于10 mg·L^(-1)时,吸附率均在60%以上。接种B9可促进污染土壤中的Cd从弱酸可溶态向可还原态和残渣态转化。添加3 m L(接种量为1.44×1011cfus)和10 m L(接种量为4.8×1011cfus)B9菌悬液处理能使弱酸可溶态Cd含量分别减少22.17%和25.06%,可还原态Cd含量分别增加9.66%和12.17%,对可氧化态Cd含量无明显影响,残渣态Cd2+含量分别增加13.55%和13.61%。研究结果可为Cd污染土壤微生物修复方法及菌株B9的实际应用提供数据参考与理论支持。展开更多
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.
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.
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.
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.
文摘针对超高温灭菌(ultra-high temperature treated,UHT)乳在货架期内出现的脂肪上浮、水乳分离、沉淀等品质劣变问题,利用高通量测序和生物信息学等技术方法,对大型乳企采集的9份在货架期内品质劣变的UHT乳和正常质量的UHT乳样品的理化指标、酶活性、微生物菌群进行了分析比较,并通过关联分析解析UHT灭菌乳品质劣变的关联微生物。结果表明:品质劣变UHT乳在理化指标、酶活性和微生物群分布方面与正常UHT乳有明显不同,假单胞杆菌、不动杆菌为品质劣变UHT乳中核心功能微生物且均属于常见的嗜冷菌,能够产生耐热酶,这可能是导致UHT乳腐败变质的主要原因。本研究为进一步解决UHT乳品质劣变问题提供了参考。
文摘通过传统的分离方法和室内培养实验,从Cd污染土壤中筛选和分离出一株对Cd2+吸附率高的菌株B9,并分析B9对土壤Cd形态的影响,探究其在Cd污染土壤修复中应用的可行性。16S r RNA序列分析结果表明,B9与食酸代尔福特菌(Delftia acidovorans,登录号NC010002)的16S r RNA序列具有99%的同源性,结合形态和生理生化指标,将其鉴定为代尔福特菌。研究结果表明,B9在pH=8、温度为35℃、培养时间为48 h时,对Cd2+的吸附效果最好,且Cd2+浓度低于10 mg·L^(-1)时,吸附率均在60%以上。接种B9可促进污染土壤中的Cd从弱酸可溶态向可还原态和残渣态转化。添加3 m L(接种量为1.44×1011cfus)和10 m L(接种量为4.8×1011cfus)B9菌悬液处理能使弱酸可溶态Cd含量分别减少22.17%和25.06%,可还原态Cd含量分别增加9.66%和12.17%,对可氧化态Cd含量无明显影响,残渣态Cd2+含量分别增加13.55%和13.61%。研究结果可为Cd污染土壤微生物修复方法及菌株B9的实际应用提供数据参考与理论支持。
