scholarly journals Microbial degradation of alkylbenzenesulphonates. Metabolism of homologues of short alkyl-chain length by an Alcaligenes sp

1974 ◽  
Vol 140 (2) ◽  
pp. 121-134 ◽  
Author(s):  
J. Anthony Bird ◽  
Ronald B. Cain
Keyword(s):  
Alkyl Chain ◽  
Sole Source ◽  
Oxidation Products ◽  
Ring Cleavage ◽  
Growth Substrate ◽  
First Order ◽  
Heat Treated ◽  
Catechol 1,2 Dioxygenase ◽  
Benzene Toluene ◽  
Ortho Pathway

1. An organism isolated from sewage and identified as an Alcaligenes sp. utilized benzenesulphonate, toluene-p-sulphonate or phenylethane-p-sulphonate as sole source of carbon and energy for growth. Higher alkylbenzenesulphonate homologues and the hydrocarbons, benzene, toluene, phenylethane and 1-phenyldodecane were not utilized. 2. 2-Phenylpropanesulphonate was metabolized to 4-isopropylcatechol. 3. 1-Phenylpropanesulphonate was metabolized to an ortho-diol, which was tentatively identified, in the absence of an authentic specimen, as 4-n-propylcatechol. 4. In the presence of 4-isopropylcatechol, which inhibited catechol 2,3-dioxygenase, 4-ethylcatechol accumulated in cultures growing on phenylethane-p-sulphonate. 5. Authentic samples of catechol, 3-methylcatechol, 4-methylcatechol, 4-ethylcatechol and 3-isopropylcatechol were oxidized by heat-treated extracts to the corresponding 2-hydroxyalkylmuconic semialdehydes. Ring cleavage occurred between C-2 and C-3. 6. The catechol derived from 1-phenylpropanesulphonate was oxygenated by catechol 2,3-dioxygenase to a compound with all the properties of a 2-hydroxyalkylmuconic semialdehyde, but it was not rigorously identified. 7. The catechol 2,3-dioxygenase induced by growth on benzenesulphonate, toluene-p-sulphonate or phenylethane-p-sulphonate showed a constant ratio of specific activities with catechol, 3-methylcatechol, 4-methylcatechol and 4-ethylcatechol that was independent of the growth substrate. At 60°C, activity towards these substrates declined at an identical first-order rate. 8. Enzymes of the ‘ortho’ pathway of catechol metabolism were present in small amounts in cells grown on benzenesulphonate, toluene-p-sulphonate or phenylethane-p-sulphonate. 9. The catechol 1,2-dioxygenase oxidized the alkylcatechols, but the rates and the total extents of oxidation were less than for catechol itself. The oxidation products of these alkylcatechols were not further metabolized.

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.

scholarly journals Microbial metabolism of the pyridine ring. Metabolism of 2- and 3-hydroxypyridines by the maleamate pathway in Achromobacter sp

1974 ◽  
Vol 140 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Ronald B. Cain ◽  
Charles Houghton ◽  
Keith A. Wright
Keyword(s):  
Pyridine Ring ◽  
Chelating Agents ◽  
Cleavage Product ◽  
Ring Cleavage ◽  
Growth Substrate ◽  
Specific Requirement ◽  
Heat Treated ◽  
C And N ◽  
Achromobacter Sp ◽  
Do So

1. Washed suspensions of two Achromobacter species (G2 and 2L), capable of growth upon 2- and 3-hydroxypyridine respectively as sources of C and N, rapidly oxidized their growth substrate pyridine-2,5-diol (2,5-dihydroxypyridine) and the putative ring-cleavage product maleamate without a lag. Suspensions derived from fumarate plus (NH4)2SO4 cultures were unable to do so. 2. Extracts of both bacteria oxidized pyridine-2,5-diol with the stoicheiometry of an oxygenase forming 1mol of NH3/mol of substrate. 3. Heat-treated extracts, however, formed maleamate and formate with little free NH3. 4. The conversion of maleamate into maleate plus NH3 by extracts of strain 2L, fractionated with (NH4)2SO4, and the metabolism of maleamate and maleate to fumarate by extracts of both strains demonstrated the existence of the enzymes catalysing each reaction of the maleamate pathway in these bacteria. 5. The pyridine-2,5-diol dioxygenase (mol.wt. approx. 340000) in extracts of these Achromobacter species required Fe2+ (1.7μm) to restore full activity after dialysis or treatment with chelating agents; the enzyme from strain 2L also had a specific requirement for l-cysteine (6.7mm), which could not be replaced by GSH or dithiothreitol. 6. The oxygenase was strongly inhibited in a competitive manner by the isomeric pyridine-2,3- and -3,4-diols.

scholarly journals Aromatic Hydroxylation of Indan by o-Xylene-Degrading Rhodococcus sp. Strain DK17

2009 ◽  
Vol 76 (1) ◽  
pp. 375-377 ◽  
Author(s):  
Dockyu Kim ◽  
Choong Hwan Lee ◽  
Jung Nam Choi ◽  
Ki Young Choi ◽  
Gerben J. Zylstra ◽  
...  
Keyword(s):  
Reverse Transcription ◽  
Ring Cleavage ◽  
Growth Substrate ◽  
Aromatic Moiety ◽  
Reverse Transcription Pcr ◽  
Aromatic Hydroxylation ◽  
Rhodococcus Sp

ABSTRACT The metabolically versatile Rhodococcus sp. strain DK17 utilizes indan as a growth substrate via the o-xylene pathway. Metabolite and reverse transcription-PCR analyses indicate that o-xylene dioxygenase hydroxylates indan at the 4,5 position of the aromatic moiety to form cis-indan-4,5-dihydrodiol, which is dehydrogenated to 4,5-indandiol by a dehydrogenase. 4,5-Indandiol undergoes ring cleavage by a meta-cleavage dioxygenase.

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.

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.

scholarly journals Influence of Oxygen-Containing Sulfur Flavor Molecules on the Stability of β-Carotene under UVA Irradiation

Molecules ◽  
2019 ◽  
Vol 24 (2) ◽  
pp. 318 ◽  
Author(s):  
Gong-Liang Zhang ◽  
Hong-Yan Wu ◽  
Ying Liang ◽  
Jie Song ◽  
Wei-Qi Gan ◽  
...  
Keyword(s):  
Sulfur Atom ◽  
Critical Role ◽  
Oxidation Products ◽  
First Order ◽  
Uva Irradiation ◽  
First Order Kinetics ◽  
Dynamic Degradation ◽  
The Stability ◽  
Ethanol System ◽  
Β Carotene

The influence of 11 kinds of oxygen-containing sulfur flavor molecules was examined on β-carotene stability under UVA irradiation in ethanol system. Both the effects of sulfides on dynamic degradation of β-carotene and the relation between structure and effect were investigated. The oxidation products of β-carotene accelerated by sulfides under UVA irradiation were also identified. The results indicated that the disulfides had more obvious accelerative effects on the photodegradation of β-carotene than mono sulfides. The degradation of β-carotene after methyl (2-methyl-3-furyl) disulfide (MMFDS), methyl furfuryl disulfide (MFDS) and bis(2-methyl-3-furyl) disulfide (BMFDS) exposure followed first-order kinetics. Furan-containing sulfides such as MMFDS and BMFDS showed more pronounced accelerative effects than their corresponding isomers. The oxidation products were identified as 13-cis-β-carotene, 9,13-di-cis-β-carotene and all-trans-5,6-epoxy-β-carotene. These results suggest that both the sulfur atom numbers and the furan group in oxygen-containing sulfides play a critical role in the photooxidation of β-carotene.

The degradation of p-toluenesulfonate by a Pseudomonas

1970 ◽  
Vol 16 (5) ◽  
pp. 309-316 ◽  
Author(s):  
D. D. Focht ◽  
F. D. Williams
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Uptake ◽  
Aromatic Compounds ◽  
Carbon Sources ◽  
Sole Source ◽  
Carbon Chain ◽  
Ring Cleavage ◽  
Resting Cells ◽  
Resting Cell ◽  
Complete Mineralization

A Pseudomonas isolated from sewage was adapted to use p-toluenesulfonate as the sole source of both carbon and sulfur. Very few of over 30 aromatic compounds tested were used for growth as sole carbon sources. Significantly, sulfobenzoate, phenolsulfonates, and isomers of cresolsulfonates did not support growth. Respirometry studies with washed, resting cells showed similar results. In both studies, benzenesulfonate was always used more rapidly than p-toluenesulfonate. The degradation of p-toluenesulfonate was shown to be over 90% of the theoretical value required for complete mineralization to carbon dioxide, water, and sulfate. When resting cells were incubated with 35S-p-toluenesulfonate, the ratio of oxygen uptake to 35S-sulfate liberation remained constant during the complete degradation period. Radiochromatographic analysis showed no 35S-aromatic intermediates in resting-cell supernatants at any time. Resting cells previously incubated with 35S-p-toluenesulfonate liberated two 35S-labeled aromatic intermediates upon disruption. Resting cells incubated with 1-14C-p-toluenesulfonate produced labeled 3-methylcatechol, labeled acetate, and unlabeled pyruvate. The labeled intermediate, 3-methylcatechol, was degraded by cell-free extracts to labeled acetate. Hydroxylation, desulfonation, ring cleavage, and subsequent fissions of the carbon chain occurred in that order; all steps but the first were catalyzed by cell-free extracts.

Photolysis of 2,5- and 2,4-Dimethylpyrrole Vapors at Room Temperature

1972 ◽  
Vol 50 (11) ◽  
pp. 1678-1689 ◽  
Author(s):  
E. Chung Wu ◽  
Julian Heicklen
Keyword(s):  
Excited State ◽  
Free Radical ◽  
Room Temperature ◽  
Low Pressure ◽  
Incident Radiation ◽  
Ring Cleavage ◽  
Incident Wavelength ◽  
First Order ◽  
Electronically Excited State ◽  
Electronically Excited

Both 2,5- and 2,4-dimethylpyrrole vapors at pressures from 0.05 to 0.70 Torr were irradiated at 2139 and 2288 Å at room temperature. The products were H2, CH4, C2H6, and polymer. No ring cleavage products were found. Φ{H2} and Φ{CH4} were remarkably insensitive to which pyrrole was used, its pressure,Ia, or the wavelength of the incident radiation. They were ~0.10–0.15 and ~0.01–0.02, respectively. Φ{C2H6} was comparable to Φ{CH4} and was also invariant to which substrate was used or the incident wavelength. However Φ{C2H6} did increase at low pressure or as Ia was reduced.The effect of scavengers showed that the products were produced mainly from free radical precursors. The main primary steps are:[Formula: see text]where DMP* is an electronically excited state of the dimethylpyrrole and Fa and Fb are radical fragments. Experiments with quenching gases showed that DMP* could be quenched, but that this reaction was less important than the first-order steps below 1 Torr.

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