scholarly journals The degradative pathway of the s-triazine melamine. The steps to ring cleavage

1982 ◽  
Vol 208 (3) ◽  
pp. 679-684 ◽  
Author(s):  
K Jutzi ◽  
A M Cook ◽  
R Hütter
Keyword(s):  
Enzyme Preparation ◽  
Cyanuric Acid ◽  
Deae Cellulose ◽  
Sole Source ◽  
Ring Cleavage ◽  
Pseudomonas Sp ◽  
Degradative Pathway ◽  
Degradative Enzymes ◽  
Specific Activities ◽  
Transient Intermediate

1. The degradative pathway of melamine (1,3,5-triazine-2,4,6-triamine) was examined in Pseudomonas sp. strain A. 2. The bacterium grew with melamine, ammeline, ammelide, cyanuric acid or NH+4 as sole source of nitrogen, and each substrate was entirely metabolized. Utilization of ammeline, ammelide, cyanuric acid or NH+4 was concomitant with growth. But with melamine as substrate, a transient intermediate was detected, which was identified as ammeline by three methods. 3. Enzymes from strain A were separated by chromatography on DEAE-cellulose, and four activities were examined. 4. Melamine was converted stoichiometrically into equimolar amounts of ammeline and NH+4. 5. Ammeline was converted stoichiometrically into equimolar amounts of ammelide and NH+4; ammelide was identified by four methods. 6. Ammelide was converted stoichiometrically into equimolar amounts of cyanuric acid and NH+4; cyanuric acid was identified by four methods. 7. Cyanuric acid was converted by an enzyme preparation into an unidentified product with negligible release of NH+4. 8. The specific activities of the degradative enzymes (greater than or equal to 0.3 mkat/kg of protein) were high enough to explain the growth rate of the organism. 9. The bacterium converted 0.4 mM-melamine anaerobically into 2.3 mM-NH+4. 10. Two other pseudomonads and two strains of Klebsiella pneumoniae were also examined, with similar results. 11. The degradative pathway of melamine appears to be hydrolytic, and proceeds by three successive deaminations to cyanuric acid, which is further metabolized.

scholarly journals Ring cleavage and degradative pathway of cyanuric acid in bacteria

1985 ◽  
Vol 231 (1) ◽  
pp. 25-30 ◽  
Author(s):  
A M Cook ◽  
P Beilstein ◽  
H Grossenbacher ◽  
R Hütter
Keyword(s):  
Klebsiella Pneumoniae ◽  
Cyanuric Acid ◽  
Deae Cellulose ◽  
Sole Source ◽  
Ring Cleavage ◽  
Pseudomonas Sp ◽  
Degradative Pathway ◽  
Anoxic Conditions

The degradative pathway of cyanuric acid [1,3,5-triazine-2,4,6(1H,3H,5H)-trione] was examined in Pseudomonas sp. strain D. The bacterium grew with cyanuric acid, biuret, urea or NH4+ as sole source of nitrogen, and each substrate was entirely metabolized concomitantly with growth. Enzymes from strain D were separated by chromatography on DEAE-cellulose and three reactions were examined. Cyanuric acid (1 mol) was converted stoichiometrically into 1.0 mol of CO2 and 1.1 mol of biuret, which was conclusively identified. Biuret (1 mol) was converted stoichiometrically into 1.1 mol of NH4+, about 1 mol of CO2 and 1.0 mol of urea, which was conclusively identified. Urea (1 mol) was converted into 1.9 mol of NH4+ and 1.0 mol of CO2. The reactions proceeded under aerobic or anoxic conditions and were presumed to be hydrolytic. Data indicate that the same pathway occurred in another pseudomonad and a strain of Klebsiella pneumoniae.

scholarly journals Bacterial degradation of N-cyclopropylmelamine. The steps to ring cleavage

1984 ◽  
Vol 222 (2) ◽  
pp. 315-320 ◽  
Author(s):  
A M Cook ◽  
H Grossenbacher ◽  
R Hütter
Keyword(s):  
Cyanuric Acid ◽  
Deae Cellulose ◽  
Bacterial Degradation ◽  
Ring Cleavage ◽  
Pseudomonas Spp ◽  
Deae Cellulose Column ◽  
Cell Extracts ◽  
Specific Activities ◽  
Substrate Proteins ◽  
Cellulose Column

The s-triazine cyclopropylmelamine (N-cyclopropyl-1,3,5-triazine-2,4,6-triamine) was degraded to about 6 mol of NH4+/mol of substrate by a mixture of two bacteria (strains A and D, both Pseudomonas spp.) Only strain A grew with cyclopropylmelamine as sole and limiting source of nitrogen. The organism obtained 2 mol of nitrogen/mol of substrate and excreted a product that was identified as cyclopropylammelide [6-cyclopropylamino-1,3,5-triazine-2,4(1 H,3 H)-dione]. Proteins in extracts from strain A were separated on a Sephadex G-200 column. Cyclopropylmelamine was found to be deaminated in two separable steps to cyclopropylammelide via cyclopropylammeline [4-amino-6-cyclopropylamino-1,3,5-triazine-2(1 H)-one], which was identified. Strain D could not utilize cyclopropylmelamine or cyclopropylammeline, but could utilize cyclopropylammelide (or homologue) as sole and limiting source of nitrogen and obtain about 4 mol of nitrogen/mol of substrate. Proteins in cell extracts from strain D were separated on a DEAE-cellulose column. Alkylammelides were degraded quantitatively by one enzyme fraction to 1 mol of cyanuric acid plus 1 mol of alkylamine/mol of substrate. The specific activities of enzymes in extracts of the two strains were as high as the activities observed during growth. The three activities studied in the two strains were all active under aerobic and oxygen-free conditions. The reactions appear to be hydrolytic, yielding 2 mol of NH4+ plus 1 mol of cyclopropylamine and 1 mol of cyanuric acid/mol of substrate.

The metabolism of p-fluorophenylacetic acid by a Pseudomonas sp. II. The degradative pathway

1971 ◽  
Vol 17 (5) ◽  
pp. 645-650 ◽  
Author(s):  
D. B. Harper ◽  
E. R. Blakley
Keyword(s):  
Aromatic Ring ◽  
Hydrogen Fluoride ◽  
Phenylacetic Acid ◽  
Oxidative Cleavage ◽  
Cell Suspensions ◽  
Ring Cleavage ◽  
Pseudomonas Sp ◽  
Partial Reduction ◽  
Degradative Pathway ◽  
Unstable Compound

A Pseudomonas sp. grown on p-fluorophenylacetic acid is adapted to the metabolism of phenylacetic acid, 3-fluoro-3-hexenedioic acid, monofluorosuccinic acid, monofluorofumaric acid, β-ketoadipic acid, and β-hydroxyadipic acid. Cell suspensions catalyze the lactonization of 3-fluoro-3-hexenedioic acid to give 4-carboxymethyl-4-fluorobutanolide. The results suggest that 3-fluoro-3-hexenedioic acid is an intermediate in the degradation of p-fluorophenylacetic acid, and may be metabolized by two alternate pathways, depending on the lactone formed. 4-Carboxymethyl-4-fluorobutanolide may be hydrolyzed to give 3-hydroxy-3-fluoroadipic acid, which spontaneously eliminates hydrogen fluoride to give β-ketoadipic acid. Alternatively, 3-fluoro-3-hexenedioic acid may lactonize to form 4-carboxymethyl-3-fluorobutanolide, which is then hydrolyzed to 3-keto-4-fluoroadipic and cleaved to form acetate and monofluorosuccinic acid. The latter is converted to fluorofumaric acid by fumarase to give 2-fluoromalic acid. This unstable compound decomposes to oxaloacetate and hydrogen fluoride. The mechanism of ring cleavage and the mode of formation of 3-fluoro-3-hexenedioic acid are uncertain but may involve partial reduction of the aromatic ring before oxidative cleavage.

scholarly journals A New 4-Nitrotoluene Degradation Pathway in aMycobacterium Strain

1998 ◽  
Vol 64 (2) ◽  
pp. 446-452 ◽  
Author(s):  
Tilmann Spiess ◽  
Frank Desiere ◽  
Peter Fischer ◽  
Jim C. Spain ◽  
Hans-Joachim Knackmuss ◽  
...  
Keyword(s):  
Sole Source ◽  
Degradation Pathway ◽  
Ring Cleavage ◽  
Resting Cells ◽  
Oxidative Dimerization ◽  
Anaerobic Conditions ◽  
Degradative Pathway ◽  
Cell Extracts ◽  
Acid Catalyzed ◽  
Homologous Substrate

ABSTRACT Mycobacterium sp. strain HL 4-NT-1, isolated from a mixed soil sample from the Stuttgart area, utilized 4-nitrotoluene as the sole source of nitrogen, carbon, and energy. Under aerobic conditions, resting cells of the Mycobacterium strain metabolized 4-nitrotoluene with concomitant release of small amounts of ammonia; under anaerobic conditions, 4-nitrotoluene was completely converted to 6-amino-m-cresol. 4-Hydroxylaminotoluene was converted to 6-amino-m-cresol by cell extracts and thus could be confirmed as the initial metabolite in the degradative pathway. This enzymatic equivalent to the acid-catalyzed Bamberger rearrangement requires neither cofactors nor oxygen. In the same crucial enzymatic step, the homologous substrate hydroxylaminobenzene was rearranged to 2-aminophenol. Abiotic oxidative dimerization of 6-amino-m-cresol, observed during growth of theMycobacterium strain, yielded a yellow dihydrophenoxazinone. Another yellow metabolite (λmax, 385 nm) was tentatively identified as 2-amino-5-methylmuconic semialdehyde, formed from 6-amino-m-cresol bymeta ring cleavage.

scholarly journals Purification and subunit structure of argininosuccinate lyase from Chlamydomonas reinhardi

1977 ◽  
Vol 167 (1) ◽  
pp. 71-75 ◽  
Author(s):  
R F Matagne ◽  
J P Schlösser
Keyword(s):  
Enzyme Activity ◽  
Crude Extract ◽  
Enzyme Preparation ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Activity Analysis ◽  
Disc Electrophoresis ◽  
Subunit Structure ◽  
Argininosuccinate Lyase

Argininosuccinate lyase (EC 4.3.2.1) was purified by (NH4)2SO4 fractionation, chromatography on DEAE-cellulose and gel filtration on Sephadex G-200. The final enzyme preparation was purified 46-fold compared with the crude extract. Electrophoresis of this preparation revealed three bands, the major one having the enzyme activity. Analysis of the enzyme by gel filtration and by disc electrophoresis (in two different concentrations of acrylamide) gave mol.wts. of 200000 (+/- 15000) and 190000 (+/- 20000) respectively. Treatment with sodium dodecyl sulphate and mercaptoethanol dissociated the enzyme into subunits of mol.wt. 39000 (+/-2000). The results are indicative of the multimeric structure of the enzyme, which is composed of five (perhaps four or six) identical subunits.

Differential Roles of Three Different Upper Pathway Meta Ring Cleavage Product Hydrolases in the Degradation of Dibenzo- p -dioxin and Dibenzofuran by Sphingomonas wittichii RW1

2021 ◽  
Author(s):  
Thamer Y. Mutter ◽  
Gerben J. Zylstra
Keyword(s):  
Gene Knockout ◽  
Sole Source ◽  
Cleavage Product ◽  
Ring Cleavage ◽  
Catabolic Pathway ◽  
Double Knockout ◽  
Cleavage Enzyme ◽  
Sphingomonas Wittichii ◽  
Physiological Approach

Sphingomonas wittichii RW1 grows on the two related compounds dibenzofuran (DBF) and dibenzo- p -dioxin (DXN) as the sole source of carbon. Previous work by others (P.V. Bunz, R. Falchetto, and A.M. Cook. Biodegradation 4:171-8, 1993, doi: 10.1007/BF00695119) identified two upper pathway meta cleavage product hydrolases (DxnB1 and DxnB2) active on the DBF upper pathway metabolite 2-hydroxy-6-oxo-6-(2-hydroxyphenyl)-hexa-2,4-dienoate. We took a physiological approach to determine the role of these two enzymes in the degradation of DBF and DXN by RW1. Single knockouts of either plasmid located dbfB1 or chromosome located dbfB2 had no effect on RW1 growth on either DBF or DXN. However, a double knockout lost the ability to grow on DBF but still grew normally on DXN demonstrating that DbfB1 and DbfB2 are the only hydrolases involved in the DBF upper pathway. Using a transcriptomic-guided approach we identified a constitutively expressed third hydrolase encoded by the chromosomally located SWIT0910 gene. Knockout of SWIT0910 resulted in a strain that no longer grows on DXN but still grows normally on DBF. Thus the DbfB1 and DbfB2 hydrolases function in the DBF but not the DXN catabolic pathway and the SWIT0190 hydrolase functions in the DXN but not the DBF catabolic pathway. Importance S. wittichii RW1 is one of only a few strains known to grow on DXN as the sole course of carbon. Much of the work deciphering the related RW1 DXN and DBF catabolic pathways has involved genome gazing, transcriptomics, proteomics, heterologous expression, and enzyme purification and characterization. Very little research has utilized physiological techniques to precisely dissect the genes and enzymes involved in DBF and DXN degradation. Previous work by others identified and extensively characterized two RW1 upper pathway hydrolases. Our present work demonstrates that these two enzymes are involved in DBF but not DXN degradation. In addition, our work identified a third constitutively expressed hydrolase that is involved in DXN but not DBF degradation. Combined with our previous work, this means that the RW1 DXN upper pathway involves genes from three very different locations in the genome: an initial plasmid-encoded dioxygenase and a ring cleavage enzyme and hydrolase encoded on opposite sides of the chromosome.

scholarly journals Novel Pathway for the Degradation of 2-Chloro-4-Nitrobenzoic Acid by Acinetobacter sp. Strain RKJ12

2011 ◽  
Vol 77 (18) ◽  
pp. 6606-6613 ◽  
Author(s):  
Dhan Prakash ◽  
Ravi Kumar ◽  
R. K. Jain ◽  
B. N. Tiwary
Keyword(s):  
Salicylic Acid ◽  
Tricarboxylic Acid Cycle ◽  
Sole Source ◽  
Degradation Pathway ◽  
Ring Cleavage ◽  
Muconic Acid ◽  
Content Type ◽  
Nitrobenzoic Acid ◽  
Catabolic Genes ◽  
Catechol 1,2 Dioxygenase

ABSTRACTThe organismAcinetobactersp. RKJ12 is capable of utilizing 2-chloro-4-nitrobenzoic acid (2C4NBA) as a sole source of carbon, nitrogen, and energy. In the degradation of 2C4NBA by strain RKJ12, various metabolites were isolated and identified by a combination of chromatographic, spectroscopic, and enzymatic activities, revealing a novel assimilation pathway involving both oxidative and reductive catabolic mechanisms. The metabolism of 2C4NBA was initiated by oxidativeorthodehalogenation, leading to the formation of 2-hydroxy-4-nitrobenzoic acid (2H4NBA), which subsequently was metabolized into 2,4-dihydroxybenzoic acid (2,4-DHBA) by a mono-oxygenase with the concomitant release of chloride and nitrite ions. Stoichiometric analysis indicated the consumption of 1 mol O2per conversion of 2C4NBA to 2,4-DHBA, ruling out the possibility of two oxidative reactions. Experiments with labeled H218O and18O2indicated the involvement of mono-oxygenase-catalyzed initial hydrolytic dechlorination and oxidative denitration mechanisms. The further degradation of 2,4-DHBA then proceeds via reductive dehydroxylation involving the formation of salicylic acid. In the lower pathway, the organism transformed salicylic acid into catechol, which was mineralized by theorthoring cleavage catechol-1,2-dioxygenase tocis, cis-muconic acid, ultimately forming tricarboxylic acid cycle intermediates. Furthermore, the studies carried out on a 2C4NBA−derivative and a 2C4NBA+transconjugant demonstrated that the catabolic genes for the 2C4NBA degradation pathway possibly reside on the ∼55-kb transmissible plasmid present in RKJ12.

Transformation of Alachlor by Microbial Communities

Weed Science ◽  
1990 ◽  
Vol 38 (4-5) ◽  
pp. 416-420 ◽  
Author(s):  
Hone L. Sun ◽  
Thomas J. Sheets ◽  
Frederick T. Corbin
Keyword(s):  
Carbon Source ◽  
Growth Medium ◽  
Basal Medium ◽  
Sole Source ◽  
Ring Cleavage ◽  
Side Chain ◽  
Microbial Culture ◽  
Mixed Microbial Culture ◽  
Alternative Carbon Source ◽  
Thin Layer Chromatographic Analysis

A mixed microbial culture able to transform alachlor at a concentration of 50 μg ml-1was obtained from alachlor-treated soil after an enrichment period of 84 days. The microbial community was composed of seven strains of bacteria. No single isolate was able to utilize alachlor as a sole source of carbon. There was no alachlor left in the enriched culture after a 14-day incubation, but only 12% of the14C-ring-labeled alachlor was converted to14CO2through ring cleavage during 14 days in the basal medium amended with alachlor as a sole carbon source. The presence of sucrose as an alternative carbon source decreased the mineralization potential of the enriched culture, but sucrose increased the mineralizing ability of a three-member mixed culture. Thin-layer chromatographic analysis showed that there were four unidentified metabolites of alachlor produced by the enriched culture. Sucrose decreased the amount of two of the four metabolites. The absence of a noticeable decline in radioactivity beyond the initial 12% suggested that the side chain of alachlor was utilized as carbon source by the enriched culture. Little difference in radioactivity between growth medium and cell-free supernatant of the growth medium suggested that the carbon in the ring was not incorporated into the cells of the degrading microorganisms.

Biochemical pathway and degradation of phthalate ester isomers by bacteria

2005 ◽  
Vol 52 (8) ◽  
pp. 241-248 ◽  
Author(s):  
J.-D. Gu ◽  
J. Li ◽  
Y. Wang
Keyword(s):  
Aromatic Ring ◽  
Enrichment Culture ◽  
Klebsiella Oxytoca ◽  
Sole Source ◽  
Phthalate Ester ◽  
Ring Cleavage ◽  
Mangrove Sediment ◽  
Individual Species ◽  
Dimethyl Phthalate ◽  
Dimethyl Phthalate Ester

Degradation of dimethyl isophthalate (DMI) and dimethyl phthalate ester (DMPE) was investigated using microorganisms isolated from mangrove sediment of Hong Kong Mai Po Nature Reserve. One enrichment culture was capable of utilizing DMI as the sole source of carbon and energy, but none of the bacteria in the enrichment culture was capable of degrading DMI alone. In co-culture of two bacteria, degradation was observed proceeding through monomethyl isophthalate (MMI) ester and isophthalic acid (IPA) before the aromatic ring opening. Using DMI as the sole carbon and energy source, Klebsiella oxytoca Sc and Methylobacterium mesophilicum Sr degraded DMI through the biochemical cooperation. The initial hydrolytic reaction of the ester bond was by K. oxytoca Sc and the next step of transformation was by M. mesophilicum Sr, and IPA was degraded by both of them. In another investigation, a novel bacterium, strain MPsc, was isolated for degradation of dimethyl phthalate ester (DMPE) also from the mangrove sediment. On the basis of phenotypic, biochemical and 16S rDNA gene sequence analyses, the strain MPsc should be considered as a new bacterium at the genus level (8% differences). This strain, together with a Rhodococcus zopfii isolated from the same mangrove sediment, was able to degrade DMPE aerobically. The consortium consisting of the two species degraded 450mg/l DMPE within 3 days as the sole source of carbon and energy, but none of the individual species alone was able to transform DMPE. Furthermore, the biochemical degradation pathway proceeded through monomethyl phthalate (MMP), phthalic acid (PA) and then protocatechuate before aromatic ring cleavage. Our results suggest that degradation of complex organic compounds including DMI and DMPE may be carried out by several members of microorganisms working together in the natural environments.

Sign in / Sign up

Export Citation Format

Share Document