Metabolism of 2-chloro-4-methylphenoxyacetate by Alcaligenes eutrophus JMP 134

2-Chloro-4-methylphenoxyacetate is not a growth substrate for Alcaligenes eutrophus JMP 134 and JMP 1341. It is, however, being transformed by enzymes of 2,4-dichlorophenoxyacetic acid metabolism to 2-chloro-4-methyl-cis, cis-muconate, which is converted by enzymatic 1,4-cycloisomerization to 4-carboxymethyl-2-chloro-4-methylmuconolactone as a dead end metabolite. Chemically, only 3,6-cycloisomerization occurs, giving rise to both diastereomers of 4-carboxychloromethyl-3-methylbut-2-en-4-olide. Those lactones harbonring a chlorosubstituent on the 4-carboxymethyl side chain were surprisingly stable under physiological as well as acidic conditions.     

Degradation of chlorosubstituted aromatic compounds by Pseudomonas sp. strain B13: fate of 3,5-dichlorocatechol

The degradation of 3,5-dichlorocatechol by enzymes of 3-chlorobenzoate-grown cells of Pseudomonas sp. strain B13 was studied. The following compounds were formed from 3,5-dichlorocatechol: trans-2-chloro-4-carboxymethylenebut-2-en-4-olide, cis-2-chloro-4-carboxymethylenebut-2-en-4-olide, and chloroacetylacrylate as the decarboxylation product of 2-chloromaleylacetate. They were identified by chromatographic and spectroscopic methods (UV, MS, PMR). An enzyme activity converting trans-2-chloro-4-carboxymethylenebut-2-en-4-olide into the cis-isomer was observed.Abbreviations 3CB 3-chlorobenzoate - 4CB 4-chlorobenzoate - 3,5DCB 3,5-dichlorobenzoate - 2,4D 2,4-dichlorophenoxyacetate - NOE Nuclear-Overhauser-Effect     

DN2菌降解烟碱的动力学及其应用研究

研究了菌株DN2降解烟碱的特性和对烟草废弃物中烟碱的降解情况。结果表明,该菌降解烟碱的最适条件为接种量为5 %,温度30 ℃,初始pH值为6.5。在该条件下,对初始烟碱浓度为500 mg/L的降解过程进行考察。结果表明,未经烟碱诱导的降解曲线呈倒S曲线,半衰期为17.43 h;经烟碱诱导的降解曲线符合Eckenfelder动力学模型,半衰期为4.10 h。添加0.1 %(质量分数)葡萄糖,可提高菌株DN2的烟碱耐受浓度,达5000 mg/L。菌株DN2能够降解烟草废弃物水提液中的烟碱（烟碱含量约为2220 mg/L）,60 h时烟碱的降解率为95.22 %,表明该菌在治理烟碱污染环境方面具有应用价值。     

Selective and reversible inhibition of the ATPase of Micrococcus denitrificans by 7-chloro-4-nitrobenzo-2-oxa-1,3 diazole

The covalent inhibitor of the beef heart mitochondrial ATPase 7-chloro-4-nitrobenzo-2-oxa-1,3 diazole inhibits the ATPase of phosphorylating particles prepared from Micrococcus denitrificans. Inhibition of both ATP synthesis and ATP hydrolysis occurs at similar rates, with a similar pH dependence, and in each case the inhibition is relieved by treatment with dithiothreitol. These results are compared with those previously obtained with the mitochondrial ATPase.     

聚丙烯二氧化钛负载膜固定化活性污泥对污水处理的研究

利用聚丙烯二氧化钛负载膜为载体,吸附固定活性污泥微生物,处理有机废水,考察了聚丙烯膜的组成、吸咐固定时间以及聚丙烯二氧化钛活性污泥负载膜对污水有机物的降解。由全有机碳分析仪对降解过程的有机物进行检测;结果表明;活性污泥负载膜处理废水8小时后,废水中的有机物含量下降达50％-60％,对所处理的废水的降解效果明显。     

Catabolism of 2,7-dichloro- and 2,4,8-trichlorodibenzofuran by Sphingomonas sp strain RW1

Due to their physicochemical and toxicological properties, polychlorinated dibenzofurans are regarded as a class of compounds providing reason for serious environmental concern. While the nonhalogenated basic structure dibenzofuran is effectively mineralized by appropriate bacterial strains, its polychlorinated derivatives are not. To elucidate the ability of the strain Sphingomonas sp RW1 to metabolize some of these chlorinated derivatives, we performed turnover experiments using 2,7-dichloro- and 2,4,8-trichlorodibenzofuran. As indicated by the oxygen-uptake rates determined for these two chlorinated dibenzofurans, Sphingomonassp RW1 can catabolize these chlorinated dibenzofurans yielding small quantities of oxidation products, which we isolated and subsequently characterized employing GC/MS and ¹H- as well as ¹³C-NMR spectroscopy. In the case of 2,7-dichlorodibenzofuran, two metabolites accumulated, which we identified as 6-chloro- and 7-chloro-2-methyl-4H-chromen-4-one. The single metabolite isolated from the turnover experiments performed with 2,4,8-trichlorodibenzofuran was unequivocally identified as 6,8-dichloro-2-methyl-4H-chromen-4-one. Received 26 April 1999/ Accepted in revised form 23 July 1999     

Isolation and identification of two novel butenolides as products of dimethylbenzoate metabolism by Rhodococcus rhodochrous N75

Abstract 3,4-Dimethylbenzoic acid and 3,5-dimethylbenzoic acid were both oxidised by 4-methylbenzoate ( p -toluate)-grown cells of Rhodococcus rhodochrous N75 via the ortho -pathway through the intermediates 3,4- and 3,5-dimethylcatechol, respectively. Owing to the formation of the two novel dead-end metabolites, 4-carboxymethyl-2,3-dimethylbut-2-en-1,4-olide and 4-carboxymethyl-2,4-dimethylbut-2-en-1,4-olide from these substrates, 3,4- and 3,5-dimethylbenzoate did not serve as growth substrates for the strain.     

(+)-4-Carboxymethyl-2,4-dimethylbut-2-en-4-olide as dead-end metabolite of 2,4-dimethylphenoxyacetic acid or 2,4-dimethylphenol by Alcaligenes eutrophus JMP 134

2,4-Dimethylphenoxyacetic acid and 2,4-dimethylphenol are not growth substrates for Alcaligenes eutrophus JMP 134 although being cooxidized by 2,4-dichlorophenoxyacetate grown cells. None of the relevant catabolic pathways were induced by the dimethylphenoxyacetate. 3,5-Dimethylcatechol is not subject to metacleavage. The alternative ortho-eleavage is also unproductive and gives rise to (+)-4-carboxymethyl-2,4-dimethylbut-2-en-4-olide as a dead-end metabolite. High yields of this metabolite were obtained with the mutant Alcaligenes eutrophys JMP 134-1 which constitutively expresses the genes of 2,4-dichlorophenoxyacetic acid metabolism.     

Determination of microbial respiratory and redox activity in activated sludge

The tetrazolium salt 5-cyano-2,3-ditolyltetrazolium chloride (CTC) was used for the determination of metabolically active bacteria in active sludge. The method was adapted and optimized to the conditions of activated sludge. The colorless and nonfluorescent tetrazolium salt is readily reduced to a water-insoluble fluorescent formazan product via the microbial electron transport system and indicates mainly dehydrogenase activity. After more than 2 h incubation, no further formation of new formazan crystals was observed, although the existing crystals in active cells continued to grow at the optimal CTC-concentration of 4 mM. The dehydrogenase activity determined by direct epifluorescence microscopic enumeration did not correlate with cumulative measured activity as determined by formazan extraction. The addition of nutrients did not lead to an increase of CTC-active cells. Sample storage conditions such as low temperature or aeration resulted in a significant decrease in dehydrogenase activity within 30 min. The rapid and sensitive method is well suited for the detection and enumeration of metabolically active microorganisms in activated sludge. Extracellular redox activity was measured with the tetrazolium salt 3′-{1-[phenylamino-) carbonyl]-3,4-tetrazolium}-bis(4-methoxy-6-nitro)benzene-sulfonic acid hydrate (XTT), which remains soluble in its reduced state, after extraction of extracellular polymeric substances (EPS) with a cation exchange resin. Received 12 August 1996/ Accepted in revised form 29 May 1997     

Synthesis, characterization and antiproliferative activity of metal complexes with the Schiff base derived from the condensation 1:2 of 2,6-diformyl-4-methylphenol and 5,6-diamino-1,3-dimethyluracil

A series of mononuclear complexes with Co(II), Ni(II), Cu(II), Zn(II), Hg(II), Mo(VI) and Pd(II) containing the ligand derived from the 1:2 condensation of 2,6-diformyl-4-methylphenol and 5,6-diamino-1,3-dimethyluracil (hereafter denoted as BDFDAAU) were synthesized. The complexes were characterized by elemental analysis, thermogravimetry (TG) and differential scanning calorimetry (DSC), IR, (1)H, (13)C and (15)N NMR, UV-visible-near IR (UV-VIS-NIR), EPR and magnetic measurements. The deprotonated ligand in the phenolic oxygen shows a symmetric tridentate coordination mode through the two azomethine nitrogen atoms and the phenolic oxygen atom whereas the coordination of the neutral ligand takes place through the phenolic oxygen atom and one azomethine nitrogen atom. In the Mo(VI) complex, the ligand is bideprotonated in the phenolic oxygen and an amino group from one uracil unit; so, the coordination mode changes again into an asymmetric way: phenolic oxygen atom, one azomethine nitrogen atom and the nitrogen atom from the deprotonated amino group. The antiproliferative behaviour against the five human tumor cell lines (human neuroblastoma NB69, human breast cancer MCF-7 and EVSA-T, human glioma H4 and human bladder carcinoma cell line ECV) suggested a modulator behaviour, according to the concentration, of cell growth due to their estrogen-like characteristics.     

Metabolization of 3,5-dichlorocatechol by Alcaligenes eutrophus JMP 134

2,4-Dichloro-cis,cis-muconate is established as ringcleavage product in the degradation of 3,5-dichlorocatechol by Alcaligenes eutrophus JMP 134. The formerly described isomerization of 2-chloro-trans- to 2-chlorocis-4-carboxymethylenebut-2-en-4-olide as an essential catabolic step could not be certified.     

Transport of 2-methyl-4-amino-5-hydroxymethylpyrimidine by Salmonella typhimurium

The transport of 2-methyl-4-amino-5-hydroxymethylpyrimidine (MAHMP) by Salmonella typhimurium was studied using synthetic [methyl-³H₃]MAHMP. It was found that an active transport system existed for MAHMP, having K_m of 0.07 μM and V_max 45 nmol·min^?1·(g dry wt. cells)^?1, that required glucose as a source of energy and was pH and temperature dependent. Uptake was inhibited by cyanide, azide, N-ethylmaleimide, 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone. Uptake was also weakly inhibited by oxythiamine, but not by thiamine, 2-methyl-4-amino-5-aminomethylpyrimidine, or 4-amino-5-hydroxymethylpyrimidine, indicating that the transport system is specific for MAHMP.     

Degradation of dibenzothiophene and its metabolite 3-hydroxy-2-formylbenzothiophene by an environmental isolate

Microbial degradation of dibenzothiophene (DBT) beyond 3-hydroxy-2-formylbenzothiophene (HFBT), a commonly detected metabolite of the Kodama pathway for DBT metabolism, and the catabolic intermediates leading to its mineralization are not fully understood. The enrichment cultures cultivated from crude oil contaminated soil led to isolation of ERI-11; a natural mixed culture, selected for its ability to deplete DBT in basal salt medium (BSM). A bacterial strain isolated from ERI-11, and tentatively named A₁₁, degraded more than 90 % of the initial DBT (270 µM), present as the sole carbon and sulfur source, in 72 h. Gas chromatography–mass spectrophotometry (GC–MS) analyses of the DBT degrading A₁₁ culture medium extracts led to detection of HFBT. The metabolite HFBT, produced using A₁₁, was used in degradation assays to evaluate its metabolism by the bacteria isolated in this study. Ultra violet–visible spectrophotometry and high-performance liquid chromatography analyses established the ability of the strain A₁₁ to deplete HFBT, present as the sole sulfur and carbon source in BSM. GC–MS analyses showed the presence of 2-mercaptobenzoic acid in the HFBT degrading A₁₁ culture extracts. The findings in this study establish that the environmental isolate A₁₁ possesses the metabolic capacity to degrade DBT beyond the metabolite HFBT. The compound 2-mercaptobenzoic acid is an intermediate formed on HFBT degradation by A₁₁.     

Degradation of 2-bromo-, 2-chloro- and 2-fluorobenzoate by Pseudomonas putida CLB 250

Abstract Pseudomonas putida strain CLB 250 (DSM 5232) utilized 2-bromo-, 2-chloro- and 2-fluorobenzoate as sole source of carbon and energy. Degradation is suggested to be initiated by a dioxygenase liberating halide in the first catabolic step. After decarboxylation and rearomatization catechol is produced as a central metabolite which is degraded via the ortho-pathway. After inhibition of ring cleavage activities with 3-chlorocatechol, 2-chlorobenzoate was transformed to catechol in nearly stoichiometric amounts. Other ortho -substituted benzoates like anthranilate and 2-methoxybenzoate seem to be metabolized via the same route.     

假单胞菌ZWL73降解4-氯硝基苯的代谢途径研究

氯代硝基芳香烃是一类环境中难以降解的有毒污染物。一株高效分解4-氯硝基苯的假单胞菌分离于4-氯硝基苯污染土壤, 可以完全降解4-氯硝基苯, 并以之为C源、N源生长。为阐明其降解4-氯硝基苯的代谢途径, 通过对以底物生长的降解菌的酶学分析, 检测到其还原降解的两个关键酶即初始酶硝基还原酶和苯环开环酶2-氨基-5-氯酚1, 6-双加氧酶的活性; 结合其它检测如培养液中降解产物分析、相关底物生长实验结果, 确定了其降解途径是通过部分还原途径。     

假单胞菌ZWL73降解4-氯硝基苯的代谢途径研究

氯代硝基芳香烃是一类环境中难以降解的有毒污染物.一株高效分解4-氯硝基苯的假单胞菌分离于4-氯硝基苯污染土壤,可以完全降解4-氯硝基苯,并以之为C源、N源生长.为阐明其降解4-氯硝基苯的代谢途径,通过对以底物生长的降解茵的酶学分析,检测到其还原降解的两个关键酶即初始酶硝基还原酶和苯环开环酶2-氨基-5-氯酚1,6-双加氧酶的活性:结合其它检测如培养液中降解产物分析、相关底物生长实验结果,确定了其降解途径是通过部分还原途径.     

Degradation of glyceraldehyde-3-phosphate dehydrogenase triggered by 4-hydroxy-2-nonenal and 4-hydroxy-2-hexenal

Lipid peroxidation products such as 4-hydroxy-2-nonenal (HNE) may be responsible for various pathophysiological events under oxidative stress, since they injure cellular components such as proteins and DNA. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which is a key enzyme of glycolysis and has been reported to be a multifunctional enzyme, is one of the enzymes inhibited by HNE. Previous studies showed that GAPDH is degraded when incubated with acetylleucine chloromethyl ketone (ALCK), resulting in the liberation of a 23-kDa fragment. In this study, we examined whether GAPDH incubated with HNE or other aldehydes of lipid peroxidation products are degraded similarly to that with ALCK. The U937 cell extract was incubated with these aldehydes at 37 degrees C and analyzed by Western blotting using anti-GAPDH antibodies. Incubation with HNE or 4-hydroxy-2-hexenal (HHE) decreased GAPDH activity and GAPDH protein level, and increased the 23-kDa fragment, in time- and dose-dependent manners, but that with other aldehydes did not. Gel filtration using the Superose 6 showed that the GAPDH-degrading activity was eluted in higher molecular fractions than proteasome activity. The enzyme activity was detected at the basic range of pH and inhibited by serine protease inhibitors, diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride, but not by other protease inhibitors including a proteasome inhibitor, MG-132, and a tripeptidyl peptidase II (TPP II) inhibitor, AAF-CMK. These results suggest that GAPDH modified by HNE and HHE is degraded by a giant serine protease, releasing the 23-kDa fragment, not by proteasome or TPP II.     

磷酸三(1-氯-2-丙基)酯降解菌筛选及其降解特性

【背景】磷酸三(1-氯-2-丙基)酯[tris-(1-chloro-2-propyl)phosphate,TCIPP]作为全球广泛关注的新兴有机污染物,具有环境赋存含量高、不易生物降解等特点,亟须开发TCIPP的高效去除技术。【目的】获得具有较高TCIPP降解效率并可用于TCIPP污染修复的新菌株。【方法】利用梯度提高无机盐培养基中TCIPP浓度的方法,从TCIPP污染土壤中筛选出1株能够降解液体中高浓度TCIPP (100 mg/L)的菌株,根据16S rRNA基因序列分析对其进行鉴定,并首次对其降解液体中TCIPP的特性进行研究。【结果】所筛选的TCIPP降解菌株DT-6为苍白杆菌(Ochrobactrum sp.),它能够利用TCIPP作为唯一碳源和能源;当TCIPP初始浓度为50 mg/L、培养时间为7 d时DT-6的生物量最大,对TCIPP的降解率也达到最高,为34.6%;蔗糖的加入能够显著促进DT-6的生长,但却抑制了其对TCIPP的降解。【结论】本研究报道了一株TCIPP高效降解菌Ochrobactrum sp. DT-6,能够为环境中TCIPP污染的生物修复提供新的种质...     

Syntrophic interactions during degradation of 4-aminobenzenesulfonic acid by a two species bacterial culture

During synthrophic growth of Hydrogenophaga palleronii (strain S1) and Agrobacterium radiobacter (strain S2) with 4-aminobenzene sulfonate (4ABS) only strain S1 desaminates 4ABS by regioselective 3,4-dioxygenation. The major part of the metabolite catechol-4-sulfonate (4CS) is excreted and further metabolized by strain S2. Although both organisms harbour activities of protocatechuate pathways assimilation of the structural analog 4CS requires first of all enzyme activities with broader substrate specificity: protocatechuate 3,4-dioxygenase and carboxymuconate cycloisomerase activities were identified which in addition to the natural substrates also convert 4CS requires first of all enzyme activities with Carboxymethyl-4-sulfobut-2-en-4-olide (4SL) was identifed as a metabolite. Its further metabolism requires a desulfonating enzyme which eliminates sulfite from (4SL) and generates maleylacetate. Convergence with the 3-oxoadipate pathway is catalyzed by a maleyl acetate reductase, which was identified in cell-free extracts of both organisms S1 and S2. Characteristically, only strain S1 can oxidize sulfite and thus contributes to the interdependence of the two bacteria during growth with 4ABS.