Microbial Degradation Rates of Natural Bitumen

Phytotoxicity of five substituted urea herbicides 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron), 3-(p-chlorophenyl)-1,1-dimethylurea (monuron), 3-phenyl-1,1-dimethylurea (fenuron), 3-hexahydro-4,7-methanoindan-5-yl) −1,1-dimethylurea (norea), and 3-(m-trifluoromethylphenyl)-1,1-dimethylurea (fluometuron) at 0, 10, 100, and 1000 ppm were determined in factorial combination at four urea nitrogen levels of 0, 45, 450, and 900 ppm with three Aspergilli: A. niger, A. sydowi, and A. tamarii. Response interactions were apparent, with all three fungi most tolerant for fenuron and least for diuron. Apparent tolerance order of the three intermediates were: A. niger, norea > fluometuron > monuron; A. sydowi, fluometuron > monuron > norea; and A. tamarii, fluometuron > norea > monuron. Oat (Avena sativa L.) bioassay for residual herbicide toxicity indicated significant differences in herbicide degradation rates between these three fungi at 5, 10, and 20 ppm in Eufaula sand. Diuron was more rapidly degraded than monuron at these levels with fluometuron and norea somewhat intermediate. A. niger was most effective in degradation of these herbicides with A. tamarii greater than A. sydowi. High nitrogen levels in soil organic matter amendment generally favored increased rates of urea herbicide degradation.

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Microbial degradation of [14C]polystyrene and 1,3-diphenylbutane

Canadian Journal of Microbiology ◽

10.1139/m78-134 ◽

1978 ◽

Vol 24 (7) ◽

pp. 798-803 ◽

Cited By ~ 24

Author(s):

M. Sielicki ◽

D. D. Focht ◽

J. P. Martin

Keyword(s):

Microbial Degradation ◽

Soil Microorganisms ◽

Phenylacetic Acid ◽

Side Chain ◽

Microbial Oxidation ◽

Initial Examination ◽

Enrichment Cultures ◽

Oxidative Reactions ◽

Degradation Rates ◽

Carbon Fragment

Microbial degradation of [β-14C]polystyrene and 1,3-diphenylbutane, a compound structurally representing the smallest repeating unit of styrene (dimer), was investigated in soil and liquid enrichment cultures. Degradation rates in soil, as determined by 14CO2 evolution from applied [14C]polystyrene, varied from 1.5 to 3.0% for a 4-month period. Although relatively low, these percentages were 15 to 30 times greater than values previously reported. Enrichment cultures, containing 1,3-diphenylbutane as the only carbon source, were used to determine the mechanisms of microbial oxidation of the polymer chain ends. Metabolism of 1,3-diphenylbutane appeared to involve the attack by a monooxygenase to form 2-phenyl-4-hydroxyphenylbutane followed by a further oxidation and subsequent fission of the benzene ring to yield 4-phenylvaleric acid and an unidentified 5-carbon fragment via the classic meta-fission pathway. Phenylacetic acid was probably formed from 4-phenylvaleric acid by subsequent β-oxidation of the side chain, methyl-oxidation, and decarboxylation. An initial examination of the population of microorganisms in the diphenylbutane enrichment cultures indicated that these oxidative reactions are carried out by common soil microorganisms of the genera Bacillus, Pseudomonas, Micrococcus, and Nocardia.

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Factors Influencing Microbial Degradation of14C-Glyphosate to14CO2in Soil

Weed Science ◽

10.1017/s0043174500064833 ◽

1978 ◽

Vol 26 (6) ◽

pp. 686-691 ◽

Cited By ~ 30

Author(s):

Loren J. Moshier ◽

Donald Penner

Keyword(s):

Microbial Degradation ◽

Sandy Loam ◽

Loamy Sand ◽

Carbon Substrate ◽

Silt Loam ◽

Limited Extent ◽

Factors Influencing ◽

Degradation Rates ◽

Glyphosate Degradation

14C-glyphosate [N-(phosphonomethyl)glycine] degradation to14CO2was examined in a Spinks sandy loam, Collamer silt loam, and a Norfolk loamy sand. After 32 days, 40, 9.5, and 3% of the14C-glyphosate was recovered as14CO2in the three soils, respectively. The degradation was primarily microbial. Phosphate additions stimulated14C-glyphosate degradation to a limited extent in the Collamer silt loam but not in the Norfolk loamy sand. Additions of Fe+++and Al+++ions reduced degradation in the Spinks sandy loam. It is postulated that formation of colloidal Fe and Al precipitates in modified soils with concomitant adsorption of14C-glyphosate is responsible for decreased availability of14C-glyphosate to microorganisms. Mn++additions were found to increase degradation. Spinks soil and carbon substrate amendments failed to substantially increase degradation rates in both soils with low degradation rates.

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Microbial degradation rates of small peptides and amino acids in the oxygen minimum zone of Chilean coastal waters

Deep Sea Research Part II Topical Studies in Oceanography ◽

10.1016/j.dsr2.2008.09.007 ◽

2009 ◽

Vol 56 (16) ◽

pp. 1055-1062 ◽

Cited By ~ 29

Author(s):

Silvio Pantoja ◽

Pamela Rossel ◽

Rodrigo Castro ◽

L. Antonio Cuevas ◽

Giovanni Daneri ◽

...

Keyword(s):

Amino Acids ◽

Microbial Degradation ◽

Coastal Waters ◽

Oxygen Minimum Zone ◽

Small Peptides ◽

Degradation Rates ◽

Minimum Zone ◽

Oxygen Minimum

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The stimulating role of syringic acid, a plant secondary metabolite, in the microbial degradation of structurally-related herbicide, MCPA

PeerJ ◽

10.7717/peerj.6745 ◽

2019 ◽

Vol 7 ◽

pp. e6745 ◽

Cited By ~ 3

Author(s):

Magdalena Urbaniak ◽

Elżbieta Mierzejewska ◽

Maciej Tankiewicz

Keyword(s):

Secondary Metabolite ◽

Microbial Degradation ◽

Microbial Community Composition ◽

Syringic Acid ◽

Bacterial Degradation ◽

Plant Secondary Metabolite ◽

Rrna Gene ◽

Plant Metabolites ◽

Chemical Structures ◽

Degradation Rates

The ability of microorganisms to degrade xenobiotics can be exploited to develop cost-effective and eco-friendly bioremediation technologies. Microorganisms can degrade almost all organic pollutants, but this process might be very slow in some cases. A promising way to enhance removal of recalcitrant xenobiotics from the environment lies in the interactions between plant exudates such as plant secondary metabolites (PSMs) and microorganisms. Although there is a considerable body of evidence that PSMs can alter the microbial community composition and stimulate the microbial degradation of xenobiotics, their mechanisms of action remain poorly understood. With this in mind, our aim was to demonstrate that similarity between the chemical structures of PSMs and xenobiotics results in higher micropollutant degradation rates, and the occurrence of corresponding bacterial degradative genes. To verify this, the present study analyses the influence of syringic acid, a plant secondary metabolite, on the bacterial degradation of an herbicide, 4-chloro-2-methylphenoxyacetic acid (MCPA). In particular, the presence of appropriate MCPA degradative genes, MCPA removal efficiency and changes in samples phytotoxicity have been analyzed. Significant MCPA depletion was achieved in samples enriched with syringic acid. The results confirmed not only greater MCPA removal from the samples upon spiking with syringic acid, and thus decreased phytotoxicity, but also the presence of a greater number of genes responsible for MCPA biodegradation. 16S rRNA gene sequence analysis revealed ubiquitous enrichment of the β-proteobacteriaRhodoferax, Achromobacter, BurkholderiaandCupriavidus. The obtained results provide further confirmation that plant metabolites released into the rhizosphere can stimulate biodegradation of xenobiotics, including MCPA.

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Degradation of Acetanilide Herbicides in History and Nonhistory Soils from Eastern Virginia

Weed Technology ◽

10.1017/s0890037x00045188 ◽

1997 ◽

Vol 11 (3) ◽

pp. 403-409 ◽

Cited By ~ 9

Author(s):

Eleni Kotoula-Syka ◽

Kriton K. Hatzios ◽

Duane F. Berry ◽

Henry P. Wilson

Keyword(s):

Thin Layer ◽

Ethyl Acetate ◽

Sodium Hydroxide ◽

Thin Layer Chromatography ◽

Microbial Degradation ◽

Degradation Rate ◽

Soil Sterilization ◽

Degradation Rates ◽

Cross Adaptation ◽

Layer Chromatography

The degradation of14C-labeled metolachlor, acetochlor, and pretilachlor in control and soils with 10-yr metolachlor- history or 3-yr butylate history was studied by monitoring the evolution of14CO2in soil biometer flasks. The degradation rate of14C-phenyl-labeled metolachlor was similar in soils with 0- and 10-yr metolachlor history over 52 d.14C was released from carbonyl-labeled metolachlor about 40% faster than from phenyl-labeled metolachlor in both soils. Soil sterilization by autoclaving reduced significantly the metolachlor degradation rate in both soils. Degradation of14C-labeled EPTC in soils with 3-yr butylate history was much faster than in soils with no history. Soil sterilization reduced the EPTC degradation rate, confirming microbial degradation. The degradation rates of acetochlor, metolachlor, and pretilachlor were similar in soils with and without butylate history. Most of the14C that remained in history and nonhistory soils was extractable with ethyl acetate or sodium hydroxide. Three major metabolites of metolachlor and EPTC were detected by thin-layer chromatography (TLC) of extracts from both soils. In contrast to the situation with carbamothioate herbicides, soils exposed repeatedly to metolachlor or other acetanilides are not prone to become adapted to these herbicides. Soils with carbamothioate history did not exhibit any apparent cross-adaptation toward acetanilide herbicides.

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