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Degradation of 4-n-nonylphenol under nitrate reducing conditions.

De Weert JP, Viñas M, Grotenhuis T, Rijnaarts HH, Langenhoff AA - Biodegradation (2010)

Bottom Line: Biodegradation of NP can reduce its toxicological risk.The largest change in diversity was observed between the enrichments of the third and fourth generation, and further enrichment did not affect the diversity.Phenol was degraded in all cases, but did not affect the linear NP degradation under denitrifying conditions and did not initiate the degradation of tNP and linear NP under the other tested conditions.

View Article: PubMed Central - PubMed

Affiliation: Deltares, Utrecht, The Netherlands. jasperien.deweert@deltares.nl

ABSTRACT
Nonylphenol (NP) is an endocrine disruptor present as a pollutant in river sediment. Biodegradation of NP can reduce its toxicological risk. As sediments are mainly anaerobic, degradation of linear (4-n-NP) and branched nonylphenol (tNP) was studied under methanogenic, sulphate reducing and denitrifying conditions in NP polluted river sediment. Anaerobic bioconversion was observed only for linear NP under denitrifying conditions. The microbial population involved herein was further studied by enrichment and molecular characterization. The largest change in diversity was observed between the enrichments of the third and fourth generation, and further enrichment did not affect the diversity. This implies that different microorganisms are involved in the degradation of 4-n-NP in the sediment. The major degrading bacteria were most closely related to denitrifying hexadecane degraders and linear alkyl benzene sulphonate (LAS) degraders. The molecular structures of alkanes and LAS are similar to the linear chain of 4-n-NP, this might indicate that the biodegradation of linear NP under denitrifying conditions starts at the nonyl chain. Initiation of anaerobic NP degradation was further tested using phenol as a structure analogue. Phenol was chosen instead of an aliphatic analogue, because phenol is the common structure present in all NP isomers while the structure of the aliphatic chain differs per isomer. Phenol was degraded in all cases, but did not affect the linear NP degradation under denitrifying conditions and did not initiate the degradation of tNP and linear NP under the other tested conditions.

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Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments of 4-n-NP degrading enrichments of various generations and dilutions originating from samples with 4-n-NP, and with 4-n-NP and phenol. The marker is equal to fourth generation 109 sample originating with phenol. A1–A4 and B1–B5 are excised bands, and the number below the lanes is the Shannon–Weaver diversity index
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Fig4: Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments of 4-n-NP degrading enrichments of various generations and dilutions originating from samples with 4-n-NP, and with 4-n-NP and phenol. The marker is equal to fourth generation 109 sample originating with phenol. A1–A4 and B1–B5 are excised bands, and the number below the lanes is the Shannon–Weaver diversity index

Mentions: DGGE profiles were made of the third generation, the 1010 dilution fourth generation, and the 101, 103 and 105 dilution fifth generation of the NP enrichment and the third generation, the 109 dilution fourth generation, and the 101 and 103 dilution fifth generation of the NP + P enrichment (Fig. 4). Band quantity and Shannon–Weaver diversity index (H′) of the NP enrichments (originating with 4-n-NP), as analyzed by DGGE (Fig. 4), varied between 12 and 14 bands and 1.01 to 1.09, respectively. This small variety in diversity index indicates that transferring and diluting the cultures did not affect the microbial diversity in these enrichments. The population remained stable. The amount of bands in the DGGE of the NP + P enrichments (originating with 4-n-NP and phenol) varied between 12 and 16, and the H′ index between 0.99 and 1.15. The lower the H′ index the less diverse the pattern is. The largest shift in diversity was observed between the third generation and fourth generation enrichment, as this enrichment step lowered the diversity from 1.15 to 1.05. However, this difference in H′ index is relatively for DGGE. Further enrichment did not affect the population because the H′ index only changed from 0.99 to 1.02 in the fifth generation enrichments.Fig. 4


Degradation of 4-n-nonylphenol under nitrate reducing conditions.

De Weert JP, Viñas M, Grotenhuis T, Rijnaarts HH, Langenhoff AA - Biodegradation (2010)

Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments of 4-n-NP degrading enrichments of various generations and dilutions originating from samples with 4-n-NP, and with 4-n-NP and phenol. The marker is equal to fourth generation 109 sample originating with phenol. A1–A4 and B1–B5 are excised bands, and the number below the lanes is the Shannon–Weaver diversity index
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3008940&req=5

Fig4: Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments of 4-n-NP degrading enrichments of various generations and dilutions originating from samples with 4-n-NP, and with 4-n-NP and phenol. The marker is equal to fourth generation 109 sample originating with phenol. A1–A4 and B1–B5 are excised bands, and the number below the lanes is the Shannon–Weaver diversity index
Mentions: DGGE profiles were made of the third generation, the 1010 dilution fourth generation, and the 101, 103 and 105 dilution fifth generation of the NP enrichment and the third generation, the 109 dilution fourth generation, and the 101 and 103 dilution fifth generation of the NP + P enrichment (Fig. 4). Band quantity and Shannon–Weaver diversity index (H′) of the NP enrichments (originating with 4-n-NP), as analyzed by DGGE (Fig. 4), varied between 12 and 14 bands and 1.01 to 1.09, respectively. This small variety in diversity index indicates that transferring and diluting the cultures did not affect the microbial diversity in these enrichments. The population remained stable. The amount of bands in the DGGE of the NP + P enrichments (originating with 4-n-NP and phenol) varied between 12 and 16, and the H′ index between 0.99 and 1.15. The lower the H′ index the less diverse the pattern is. The largest shift in diversity was observed between the third generation and fourth generation enrichment, as this enrichment step lowered the diversity from 1.15 to 1.05. However, this difference in H′ index is relatively for DGGE. Further enrichment did not affect the population because the H′ index only changed from 0.99 to 1.02 in the fifth generation enrichments.Fig. 4

Bottom Line: Biodegradation of NP can reduce its toxicological risk.The largest change in diversity was observed between the enrichments of the third and fourth generation, and further enrichment did not affect the diversity.Phenol was degraded in all cases, but did not affect the linear NP degradation under denitrifying conditions and did not initiate the degradation of tNP and linear NP under the other tested conditions.

View Article: PubMed Central - PubMed

Affiliation: Deltares, Utrecht, The Netherlands. jasperien.deweert@deltares.nl

ABSTRACT
Nonylphenol (NP) is an endocrine disruptor present as a pollutant in river sediment. Biodegradation of NP can reduce its toxicological risk. As sediments are mainly anaerobic, degradation of linear (4-n-NP) and branched nonylphenol (tNP) was studied under methanogenic, sulphate reducing and denitrifying conditions in NP polluted river sediment. Anaerobic bioconversion was observed only for linear NP under denitrifying conditions. The microbial population involved herein was further studied by enrichment and molecular characterization. The largest change in diversity was observed between the enrichments of the third and fourth generation, and further enrichment did not affect the diversity. This implies that different microorganisms are involved in the degradation of 4-n-NP in the sediment. The major degrading bacteria were most closely related to denitrifying hexadecane degraders and linear alkyl benzene sulphonate (LAS) degraders. The molecular structures of alkanes and LAS are similar to the linear chain of 4-n-NP, this might indicate that the biodegradation of linear NP under denitrifying conditions starts at the nonyl chain. Initiation of anaerobic NP degradation was further tested using phenol as a structure analogue. Phenol was chosen instead of an aliphatic analogue, because phenol is the common structure present in all NP isomers while the structure of the aliphatic chain differs per isomer. Phenol was degraded in all cases, but did not affect the linear NP degradation under denitrifying conditions and did not initiate the degradation of tNP and linear NP under the other tested conditions.

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