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.

RESPIRATION OF INTACT CELLS OF A LOW-TEMPERATURE BASIDIOMYCETE

1966 ◽  
Vol 44 (8) ◽  
pp. 1077-1086 ◽  
Author(s):  
E. W. B. Ward
Keyword(s):  
Carbon Dioxide ◽  
Low Temperature ◽  
Oxygen Uptake ◽  
Respiratory Quotient ◽  
Tricarboxylic Acid Cycle ◽  
Carbon Sources ◽  
Endogenous Respiration ◽  
Starvation Period ◽  
Intact Cells ◽  
Exogenous Glucose

Conventional manometric procedures were used to measure oxygen uptake and carbon dioxide evolution by cells of a low-temperature basidiomycete. Total respiration was lowest and, relatively, endogenous respiration was highest in old cells. During starvation, endogenous respiration decreased but did so most rapidly in young cells. Maximum response to exogenous glucose was obtained from young cells after starvation. The respiratory quotient of endogenous respiration fell from 1.0 to approximately 0.7 during starvation, indicating a change in endogenous substrate. Conversely the respiratory quotient for exogenous respiration of added glucose increased with the starvation period. The level of oxidative assimilation of glucose was shown to be high (80-90%) and evidence was obtained that exogenous glucose did not suppress endogenous respiration.The optimum temperature for oxygen uptake was 25 °C, below which the Q10 was approximately 2. At 30 °C the rate, while initially highest, decreased during the 6-hour incubation period.The fungus utilized various compounds as carbon sources, but not sucrose in short-term experiments. Glucose, but not xylose was fermented, although the ratio of carbon dioxide to ethanol was not 1:1. Inhibition by fluoride, arsenite, iodoacetate, fluoroacetate, and malonate suggested that both glucose and xylose are respired at least in part by the Embden-Meyerof pathway and the tricarboxylic acid cycle. Endogenous respiration was only slightly affected by these inhibitors.

scholarly journals Cloning, Sequencing, and Characterization of the Hexahydro-1,3,5-Trinitro-1,3,5-Triazine Degradation Gene Cluster from Rhodococcus rhodochrous

2002 ◽  
Vol 68 (10) ◽  
pp. 4764-4771 ◽  
Author(s):  
Helena M. B. Seth-Smith ◽  
Susan J. Rosser ◽  
Amrik Basran ◽  
Emma R. Travis ◽  
Eric R. Dabbs ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Gene Cluster ◽  
High Explosive ◽  
Sole Source ◽  
Ring Cleavage ◽  
Rhodococcus Rhodochrous ◽  
Resting Cell ◽  
Dead End ◽  
Adrenodoxin Reductase

ABSTRACT Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a high explosive which presents an environmental hazard as a major land and groundwater contaminant. Rhodococcus rhodochrous strain 11Y was isolated from explosive contaminated land and is capable of degrading RDX when provided as the sole source of nitrogen for growth. Products of RDX degradation in resting-cell incubations were analyzed and found to include nitrite, formaldehyde, and formate. No ammonium was excreted into the medium, and no dead-end metabolites were observed. The gene responsible for the degradation of RDX in strain 11Y is a constitutively expressed cytochrome P450-like gene, xplA, which is found in a gene cluster with an adrenodoxin reductase homologue, xplB. The cytochrome P450 also has a flavodoxin domain at the N terminus. This study is the first to present a gene which has been identified as being responsible for RDX biodegradation. The mechanism of action of XplA on RDX is thought to involve initial denitration followed by spontaneous ring cleavage and mineralization.

scholarly journals Identification and Characterization of Genes Involved in the Downstream Degradation Pathway of γ-Hexachlorocyclohexane in Sphingomonas paucimobilis UT26

2005 ◽  
Vol 187 (3) ◽  
pp. 847-853 ◽  
Author(s):  
Ryo Endo ◽  
Mayuko Kamakura ◽  
Keisuke Miyauchi ◽  
Masao Fukuda ◽  
Yoshiyuki Ohtsubo ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Gene Clusters ◽  
Sole Source ◽  
Degradation Pathway ◽  
Ring Cleavage ◽  
Sphingomonas Paucimobilis ◽  
Reductase Gene ◽  
Chlorinated Aromatic Compounds ◽  
Identification And Characterization

ABSTRACT Sphingomonas paucimobilis UT26 utilizes γ-hexachlorocyclohexane (γ-HCH) as a sole source of carbon and energy. In our previous study, we cloned and characterized genes that are involved in the conversion of γ-HCH to maleylacetate (MA) via chlorohydroquinone (CHQ) in UT26. In this study, we identified and characterized an MA reductase gene, designated linF, that is essential for the utilization of γ-HCH in UT26. A gene named linEb, whose deduced product showed significant identity to LinE (53%), was located close to linF. LinE is a novel type of ring cleavage dioxygenase that catalyzes the conversion of CHQ to MA. LinEb expressed in Escherichia coli transformed CHQ and 2,6-dichlorohydroquinone to MA and 2-chloromaleylacetate, respectively. Our previous and present results indicate that UT26 (i) has two gene clusters for degradation of chlorinated aromatic compounds via hydroquinone-type intermediates and (ii) uses at least parts of both clusters for γ-HCH utilization.

scholarly journals Elucidation of the ipso-Substitution Mechanism for Side-Chain Cleavage of α-Quaternary 4-Nonylphenols and 4-t-Butoxyphenol in Sphingobium xenophagum Bayram

2007 ◽  
Vol 73 (10) ◽  
pp. 3320-3326 ◽  
Author(s):  
Frédéric L. P. Gabriel ◽  
Maike Cyris ◽  
Niels Jonkers ◽  
Walter Giger ◽  
Klaus Guenther ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Hydroxy Group ◽  
Ring Cleavage ◽  
Resting Cells ◽  
Major Pathway ◽  
Cell Extracts ◽  
Ipso Substitution ◽  
Chain Cleavage ◽  
Substitution Mechanism ◽  
Alkyl Moiety

ABSTRACT Recently we showed that degradation of several nonylphenol isomers with α-quaternary carbon atoms is initiated by ipso-hydroxylation in Sphingobium xenophagum Bayram (F. L. P. Gabriel, A. Heidlberger, D. Rentsch, W. Giger, K. Guenther, and H.-P. E. Kohler, J. Biol. Chem. 280:15526-15533, 2005). Here, we demonstrate with 18O-labeling experiments that the ipso-hydroxy group was derived from molecular oxygen and that, in the major pathway for cleavage of the alkyl moiety, the resulting nonanol metabolite contained an oxygen atom originating from water and not from the ipso-hydroxy group, as was previously assumed. Our results clearly show that the alkyl cation derived from the α-quaternary nonylphenol 4-(1-ethyl-1,4-dimethyl-pentyl)-phenol through ipso-hydroxylation and subsequent dissociation of the 4-alkyl-4-hydroxy-cyclohexadienone intermediate preferentially combines with a molecule of water to yield the corresponding alcohol and hydroquinone. However, the metabolism of certain α,α-dimethyl-substituted nonylphenols appears to also involve a reaction of the cation with the ipso-hydroxy group to form the corresponding 4-alkoxyphenols. Growth, oxygen uptake, and 18O-labeling experiments clearly indicate that strain Bayram metabolized 4-t-butoxyphenol by ipso-hydroxylation to a hemiketal followed by spontaneous dissociation to the corresponding alcohol and p-quinone. Hydroquinone effected high oxygen uptake in assays with induced resting cells as well as in assays with cell extracts. This further corroborates the role of hydroquinone as the ring cleavage intermediate during degradation of 4-nonylphenols and 4-alkoxyphenols.

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.

Ultrastructure of Melosira resting cell rejuvenation

1984 ◽  
Vol 42 ◽  
pp. 734-735
Author(s):  
C. E. M. Bourne ◽  
L. Sicko-Goad
Keyword(s):  
Electron Microscopy ◽  
Lake Michigan ◽  
Light And Electron Microscopy ◽  
Resting Cells ◽  
Planktonic Diatoms ◽  
Resting Cell ◽  
Vegetative Survival ◽  
Cytological Changes ◽  
Recent Attention ◽  
Freshwater Diatom

Much recent attention has been focused on vegetative survival forms of planktonic diatoms and other algae. There are several reports of extended vegetative survival of the freshwater diatom Melosira in lake sediments. In contrast to those diatoms which form a morphologically distinct resistant spore, Melosira is known to produce physiological resting cells that are indistinguishable in outward morphology from actively growing cells.We used both light and electron microscopy to document and elucidate the sequence of cytological changes during the transition from resting cells to actively growing cells in a population of Melosira granulata from Douglas Lake, Michigan sediments collected in mid-July of 1983.

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.

Breathing in brief exercise

1960 ◽  
Vol 15 (4) ◽  
pp. 583-588 ◽  
Author(s):  
F. N. Craig ◽  
E. G. Cummings
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Uptake ◽  
Respiratory Exchange Ratio ◽  
Metabolic Cost ◽  
Carbon Dioxide Tension ◽  
Minute Volume ◽  
Carbon Dioxide Output ◽  
Respiratory Minute Volume ◽  
Before And After

Two men ran for 20 or 60 seconds while inhaling air, oxygen or 4% carbon dioxide. Inspired respiratory minute volume was determined for each breath. Ventilation increased suddenly in the first breath with minimal changes in end-expiratory carbon dioxide tension and respiratory exchange ratio to a rate that remained constant for 20 seconds before increasing further. The rate of carbon dioxide output was uniform during the first 20 seconds. A 12% grade did not increase ventilation or oxygen uptake during runs of 20 seconds, but in the first minute of recovery, ventilation was 64% greater than after level runs. Inhalation of oxygen inhibited ventilation by 24% in the 20-second periods before and after the end of a 60-second run. Inhalation of carbon dioxide begun at rest produced increments in ventilation and end-expiratory carbon dioxide tension that varied little during running and recovery. In the 20-second runs ventilation varied with speed but appeared independent of ultimate metabolic cost. Submitted on January 21, 1960

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