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1.
We previously isolated Rhodococcus sp. 065240, which catalyzes the defluorination of benzotrifluoride (BTF). In order to investigate the mechanism of this degradation of BTF, we performed proteomic analysis of cells grown with or without BTF. Three proteins, which resemble dioxygenase pathway enzymes responsible for isopropylbenzene degradation from Rhodococcus erythropolis BD2, were induced by BTF. Genomic PCR and DNA sequence analysis revealed that the Rhodococcus sp. 065240 carries the gene cluster, btf, which is highly homologous to the ipb gene cluster from R. erythropolis BD2. A mutant strain, which could not catalyze BTF defluorination, was isolated from 065240 strain by UV mutagenesis. The mutant strain had one mutation in the btfT gene, which encodes a response regulator of the two component system. The defluorinating ability of the mutant strain was recovered by complementation of btfT. These results suggest that the btf gene cluster is responsible for degradation of BTF.  相似文献   

2.
Based on the finding of a novel berberine (BBR)-utilizing bacterium, Rhodococcus sp. strain BD7100, we investigated the degradation of BBR and its analog berberrubine (BRU). Resting cells of BD7100 demethylenated BBR and BRU, yielding benzeneacetic acid analogs. Isolation of benzeneacetic acid analogs suggested that BD7100 degraded the isoquinoline ring of the protoberberine skeleton. This work represents the first report of cleavage of protoberberine skeleton by a microorganism.  相似文献   

3.
Rhodococcus sp. strain DK17 is able to utilize a variety of monocyclic aromatic hydrocarbons, including benzene, phenol, toluene, and o-xylene, as growth substrates. Although DK17 is unable to grow on m- and p-xylene, this strain could transform these two xylene isomers to some extent after induction by o-xylene. The major accumulating compounds formed during the degradation of m- and p-xylene by DK17 were isolated by high-pressure liquid chromatography and identified by gas chromatography-mass spectrometric and (1)H nuclear magnetic resonance spectral techniques. Both xylene isomers were transformed to dihydroxylated compounds by what must be two successive hydroxylation events: m-xylene was converted to 2,4-dimethylresorcinol and p-xylene was converted to 2,5-dimethylhydroquinone. The rigorous structural identification of 2,4-dimethylresorcinol and 2,5-dimethylhydroquinone demonstrates that DK17 can perform distinct regioselective hydroxylations depending on the position of the substituent groups on the aromatic ring.  相似文献   

4.
5.
Aims:  The aim of this study is to isolate and characterize organisms capable of utilizing high concentration atrazine from the contaminated sites.
Methods and Results:  A selective enrichment was used for isolating atrazine-degrading organisms from the contaminated sites resulting in isolation of an efficient atrazine-degrading organism designated as strain MB-P1. On the basis of 16S rRNA gene sequencing, total cellular fatty acid analysis and physiological and biochemical tests, strain MB-P1 was identified as a member of genus Rhodococcus . High performance liquid chromatography was performed to identify the atrazine degradation intermediates demonstrating that the degradation proceeds via formation of 'de-ethylatrazine' and 'de-isopropylatrazine'. Further, plasmid curing by SDS method showed atrazine-degrading gene(s) to be plasmid-encoded.
Conclusions:  We have successfully isolated a Rhodococcus sp. strain MB-P1 which is capable of utilizing atrazine as sole source of carbon and energy at very high concentrations of 1000 ppm. The pathway for degradation of atrazine has also been determined. The metabolic gene(s) responsible for atrazine degradation was found to be plasmid-encoded.
Significance and Impact of the Study:  Rhodococcus sp. strain MB-P1 could be used as an ideal model system for in-situ degradation and restoration of ecological niches which are heavily contaminated with atrazine.  相似文献   

6.
红球菌DS—3脱除二苯并噻吩中有机硫的性能初探   总被引:16,自引:2,他引:16  
从孤岛油田分离到一株红球菌(Rhodococcus sp.)DS—3,能专一地切断二苯并噻吩(DBT)中的C-S键,沿4S途径代谢,生成二羟联苯。实验证明,以2%的接种量脱除50μg/mL DBT底物中的硫效果最佳。在此条件下,适宜菌株生长和脱硫的碳源为葡萄糖,氯源为硝酸铵,初始PH为8.2,生长温度为30℃,15mmol/L的硫酸根离子能使其丧失脱硫能力。在上述适宜条件下,培养72h后DBT中34.04%的硫被脱除。  相似文献   

7.
Alkyl ether-degrading Rhodococcus sp. strain DEE5151, isolated from activated sewage sludge, has an activity for the oxidation of a variety of alkyl ethers, aralkyl ethers and dibenzyl ether. The whole cell activity for diethyl ether oxidation was effectively inhibited by 2,3-dihydrofurane, ethyl vinyl ether and glutaraldehyde. Glutaraldehyde of less than 30 microM inhibited the activity by a competitive manner with the inhibition constant, K(I) of 7.07+/-1.36 microM. The inhibition type became mixed at higher glutaraldehyde concentrations >30 microM, probably due to the inactivation of the cell activity by the Schiff-base formation. Structurally analogous ethyl vinyl ether inhibited the diethyl ether oxidation activity in a mixed manner with decreasing the apparent maximum oxidation rate, v(max)(app), and increasing the apparent Michaelis-Menten constant, K(M)(app). The mixed type inhibition by ethyl vinyl ether seemed to be introduced not only by the structure similarity with diethyl ether, but also by the reactivity of the vinyl ether with cellular components in the whole cell system.  相似文献   

8.
A benzothiophene desulfurizing bacterium was isolated and identified as Rhodococcus sp. strain T09. Growth assays revealed that this strain assimilated, as the sole sulfur source, various organosulfur compounds that cannot be assimilated by the well-studied dibenzothiophene-desulfurizing Rhodococcus sp. IGTS8. The cellular growth rate of strain T09 for the alkylated benzothiophenes depended on the alkylated position and the length of the alkyl moiety.  相似文献   

9.
Biphenyl dioxygenase is the enzyme that catalyzes the stereospecific dioxygenation of the aromatic ring. This enzyme has attracted the attention of researchers due to its ability to oxidize polychlorinated biphenyls, which is one of the serious environmental contaminants. We determined the crystal structure of the terminal oxygenase component of the biphenyl dioxygenase (BphA1A2) derived from Rhodococcus strain sp. RHA1 in substrate-free and complex forms. These crystal structures revealed that the substrate-binding pocket makes significant conformational changes upon substrate binding to accommodate the substrate into the pocket. Our analysis of the crystal structures suggested that the residues in the substrate-binding pocket can be classified into three groups, which, respectively, seem to be responsible for the catalytic reaction, the orientation/conformation of the substrate, and the conformational changes of the substrate-binding pocket. The cooperative actions of residues in the three groups seem to determine the substrate specificity of the enzyme.  相似文献   

10.
The operons encoding the transformation of phthalate to protocatechuate are duplicated and present on two different megaplasmids [pDK2 (330 kb) and pDK3 (750 kb)] in Rhodococcus sp. strain DK17. RT-PCR experiments using gene-specific primers showed that both the pDK2- and the pDK3-encoded dihydroxyphthalate decarboxylase genes are simultaneously expressed during growth on phthalate. The doubling time of the pDK2-cured mutant strain DK176 in minimal liquid medium with 5mM phthalate is 52.5% of that of the wild-type strain DK17. The data indicate that both copies of the phthalate operon are equally functional in DK17, and gene dosage is the main reason for slower growth of DK176 on phthalate.  相似文献   

11.
A novel indigo-producing oxygenase gene, designated ipoA (1,197 bp) was characterized from Rhodococcus sp. strain T104. Three indigo-negative mutations (A58V, P59L, and G251D) were obtained through random mutagenesis using an E. coli mutator strain. Subsequent saturation mutagenesis resulted in the identification of nine and three amino acid substitutions that restore activity in the A58V and P59L mutants, respectively. Activity was not restored in the G251D mutation by any other amino acids. Interestingly, activity in the A58V mutant, where a methyl group is only replaced by an isopropyl side chain, is restored by a variety of amino acids, including polar ones. A molecular modeling study suggests that the residues at positions 58, 59, and 251 of the T104 IpoA enzyme are far from the active site, indicating that the mutations must alter the overall structure of the enzyme.  相似文献   

12.
The aerobic degradation of 3- N -trimethylamino-1-propanol (homocholine) as a sole source of carbon and nitrogen has been found for a Rhodococcus sp. bacterium isolated from soil. The isolate was identified as Rhodococcus sp. strain A2 based on its phenotypic features, physiological and biochemical characteristics, and results of phylogenetic analysis. The washed cells of strain A2 completely degraded homocholine within 6 h, with concomitant formation of several metabolites. Analysis of the metabolites using capillary electrophoresis, fast atom bombardment–MS, and GC–MS showed that trimethylamine was the major metabolite, in addition to β-alanine betaine (β-AB) and trimethylaminopropionaldehyde. Therefore, the possible degradation pathway of homocholine in the isolated strain is through consequent oxidation of the alcohol group (-OH) to aldehyde (-CHO) and acid (-COOH). Thereafter, the cleavage of β-AB C–N bonds yielded trimethylamine and alkyl chain.  相似文献   

13.
AIMS: Isolation of the genes relative to PCB biodegradation and identification of the bph gene function in Rhodococcus sp. R04. METHODS AND RESULTS: A 8.7-kb fragment carrying the biphenyl catabolic genes bphABCD was isolated from the gene library in Rhodococcus sp. R04. Based on the deduced amino acid sequence homology, seven bph genes, bphA1A2A3A4, bphB, bphC and bphD, were thought to be responsible for the initial four steps of biphenyl degradation. In Escherichia coli, BphA exhibited poor activity for biphenyl transformation, and BphB, BphC and BphD were found to be catalytically active towards 2,3-dihydro-2,3-dihydroxybiphenyl, 2,3-dihydroxybiphenyl and 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate, respectively (activities of 50, 8.1 and 2.4 micromol l(-1) min(-1) mg(-1)). SDS-PAGE analysis indicated that the sizes of bphA1A2A3A4, bphB, bphC and bphD gene products were 49, 19, 14, 47, 32, 30 and 31 kDa, respectively. After disruption of bph genes, the bphA1 mutants lost the ability to grow on biphenyl, the bphB and bphD mutants were able to transform a little of biphenyl, but hardly grew on biphenyl. CONCLUSION: The cloned bph genes indeed play an important role in the biphenyl catabolism in this strain. SIGNIFICANCE AND IMPACT OF THE STUDY: This bph gene organization in Rhodococcus sp. R04 differs from that of other biphenyl degraders reported previously, indicating it is a novel type of bph gene cluster. Analysis of the phylogenetic tree suggested that BphA1 and BphA2 in Rhodococcus sp. R04 had a different evolutionary relationship with those in the other PCB degraders.  相似文献   

14.
Degradation of benzene by a Rhodococcus sp. using immobilized cell systems   总被引:1,自引:0,他引:1  
The continuous degradation of benzene by a Rhodococcus sp. using free and immobilized cell systems was compared. Cell entrapment in calcium and strontium alginate beads and adhesion on support materials such as glass beads were found to be unsatisfactory. Degradation of benzene by cells immobilized in either ceramic or cellulose carriers proved to be more efficient than its non-immobilized counterpart. A retention time of 36 h was required to effect a 97% degradation of benzene using suspended free cells while cells immobilized on cellulose or ceramic carriers effected 97% degradation at 24 and 18 h, respectively. Recycling of the ceramic carriers was also possible and resulted in an even shorter retention time of 12h to effect a 97% degradation of benzene. Cell adhesion on the support materials was confirmed by scanning electron microscopy.  相似文献   

15.
以筛选得到的红球菌SDUZAWQ为对象,研究其在不同浓度的有机硫化合物二苯并噻吩(DBT)存在下的脱硫能力,以及在0.2mmolLDBT和不同浓度Na2SO4同时存在下的脱硫情况。当DBT浓度高达6mmolL时,菌株仍能生长,而且检测出产物2-羟基联苯(2-HBP)的存在,说明该菌株具有耐受较高浓度DBT的能力。当DBT和Na2SO4同时存在时,DBT为菌株SDUZAWQ所利用,并且也检测出2-HBP,并非如文献所报道的红球菌在无机硫存在下不代谢DBT,表明该菌株能够耐受一定浓度的无机硫酸盐。对相关脱硫基因的克隆和测序结果显示,完整脱硫基因dszABC、其上游调控序列和dszD的序列与模式菌株RhodococcuserythropolisIGTS8的同源性分别是99%、100%和100%。  相似文献   

16.
孙娇  杨海燕  李力 《微生物学通报》2017,44(7):1613-1621
【目的】考察一株红球菌Rhodococcus sp.strain p52中的二噁英降解质粒pDF01(170 kb)和pDF02(242 kb)的稳定性和接合转移特性。【方法】在无选择压力的条件下对菌株p52进行连续传代培养,考察质粒pDF01、pDF02的丢失;以菌株p52为供体菌,以不同种属的菌株作受体菌,通过平板接合实验探讨质粒pDF01、pDF02接合转移的受体菌范围以及接合转移频率,利用菌落杂交、Southern杂交对质粒转移结果进行确认,利用降解实验测试转移质粒降解基因的表达。【结果】质粒pDF01和pDF02在红球菌p52中均具有较高的稳定性,在LB培养基上连续传代少于47次时pDF02可保持,连续传代少于65次时pDF01可保持。质粒pDF01和pDF02具备在同属和属间接合转移的能力,可向受体菌——紫红红球菌(Rhodococcus rhodochrous)、红串红球菌(Rhodococcus erythropolis)、大地两面神菌(Terrabacter tumescens)和节杆菌(Arthrobacter sp.)转移,其中以节杆菌作受体菌时质粒pDF01和pDF02接合转移频率最高,达到3.5×10~(-6)(接合子/受体菌);对节杆菌接合子质粒进行Southern杂交进一步确认了质粒pDF01、pDF02的存在。另外获得质粒pDF01、pDF02后的节杆菌接合子可以对二苯并呋喃高效利用,且降解能力与红球菌供体菌株p52相当。【结论】红球菌菌株p52可通过降解质粒转移强化生物修复过程,在去除环境中二噁英污染中具有良好的应用前景。  相似文献   

17.
Rhodococcus sp. DS7, isolated from a polluted soil, has shown good desulfurizing activity towards dibenzothiophene (DBT) and its derivatives, but is not able to desulfurize benzothiophene (BT), the other thiophenic molecule recalcitrant to the chemical hydrodesulfurization (HDS) process, and most abundant in gasoline. To select a Rhodococcus DS7 derivative strain able to desulfurize both DBT and BT, we took advantage of the verified capacity of this strain to integrate exogenous DNA randomly, with a good efficiency. Heterologous chromosomal DNA, digested with restriction enzymes, from two BT but not DBT desulfurizing strains, Rhodococcus sp. ATCC 27778 and Gordonia sp. ATCC 19067, was electroporated into Rhodococcus DS7. Selection on minimal medium with BT as sole sulfur source allowed us to isolate several DS7 derivatives with the capacity to desulfurize both thiophenic molecules. Two strains, one derived from the integration and recombination of DNA from ATCC 27778, and the other from ATCC 19067, have been partially characterized. These recombinant microorganisms are an interesting starting point to develop new biodesulfurization processes.  相似文献   

18.
【背景】目前,微生物所产胞外多糖(exopolysaccharide,EPS)的理化性质及其在重金属吸附中的应用受到了广泛关注。【目的】研究红球菌HX-2所产胞外多糖的理化性质,并探究其对重金属的吸附情况。【方法】使用离子交换和凝胶色谱分离法对胞外多糖粗品进行纯化;利用苯酚硫酸法测胞外多糖中糖含量;用Bradford试剂盒检测胞外多糖中蛋白含量;使用甲醇萃取法检测胞外多糖中脂质含量;用高效液相色谱(high performance liquid chromatography,HPLC)法分析胞外多糖中单糖组成;用扫描电镜(scanningelectronmicroscopy,SEM)法观察多糖表面形态;通过等温吸附模型和动力学模型探究胞外多糖对重金属的吸附效果。【结果】测得胞外多糖主要成分EPS-G-1中总糖含量为78.43%,蛋白含量为8.31%,脂质含量为8.22%;纯化后胞外多糖中单糖组成为葡萄糖、甘露糖、半乳糖、葡萄糖醛酸和岩藻糖,质量比为27.31:26.67:24.83:15.85:4.80;通过等温吸附模型拟合得到HX-2所产胞外多糖对Cu~(2+)的最大吸附量为144.93 mg/g。【结论】红球菌HX-2所产胞外多糖对水体中Cu~(2+)具有良好的吸附作用,可用于工业废水中重金属离子的处理。  相似文献   

19.
Rhodococcus rhodochrous ATCC 17895 possesses an array of mono- and dioxygenases, as well as hydratases, which makes it an interesting organism for biocatalysis. R. rhodochrous is a Gram-positive aerobic bacterium with a rod-like morphology. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 6,869,887 bp long genome contains 6,609 protein-coding genes and 53 RNA genes. Based on small subunit rRNA analysis, the strain is more likely to be a strain of Rhodococcus erythropolis rather than Rhodococcus rhodochrous.  相似文献   

20.
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