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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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Molecular structure of a linear nonylphenol and b a branched nonylphenol isomer
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Fig1: Molecular structure of a linear nonylphenol and b a branched nonylphenol isomer

Mentions: Nonylphenol (NP) is a hydrophobic compound which is widely used as intermediate in the production of nonylphenol ethoxylates (Giger et al. 1984; Liber et al. 1999). These nonylphenol ethoxylates are used in household and cleaning products as a surfactant. They are transformed in anaerobic waste water treatment plants to NP as an end product, which enters the environment via the sludges (Giger et al. 1984; Di Corcia et al. 1998). Nonylphenol exists of a mixture of isomers with a hydrophilic phenol group and a linear (4-n-NP) or a branched (tNP) carbon chain with nine carbon atoms (Fig. 1). Due to its chemical properties, it adsorbs to and accumulates in sediment (Sturm 1973; Kravetz 1983) as observed in river sediments in, e.g. Spain, Germany and Taiwan (Ding et al. 1999; Fries and Püttmann 2003; Navarro-Ortega et al. 2010). Since NP is an endocrine disruptor, degradation of NP in the sediment to non toxic compounds is of great interest (Nimrod and Benson 1996). Biodegradation under aerobic conditions is well described, as reviewed by Corvini et al. (2006). However, anaerobic degradation of NP is of greater importance since sediments are mainly anaerobic (Middeldorp et al. 2003). So far, tNP seems to be persistent under anaerobic conditions for biodegradation (Ekelund et al. 1993; Hesselsoe et al. 2001). Anaerobic biodegradation of 4-n-NP by bacteria has only been reported in sediment from the Erren River in Taiwan (Chang et al. 2004) under sulphate reducing, methanogenic and nitrate reducing conditions, respectively. Anaerobic bacterial degradation of 4-n-NP in soil and sludge from a waste water treatment plant has also been mentioned and 4-n-NP degrading strains were closely related to Bacillus niacini, Bacillus cereus and Acinetobacter baumanni (Chang et al. 2005; Chang et al. 2007).Fig. 1


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

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

Molecular structure of a linear nonylphenol and b a branched nonylphenol isomer
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3008940&req=5

Fig1: Molecular structure of a linear nonylphenol and b a branched nonylphenol isomer
Mentions: Nonylphenol (NP) is a hydrophobic compound which is widely used as intermediate in the production of nonylphenol ethoxylates (Giger et al. 1984; Liber et al. 1999). These nonylphenol ethoxylates are used in household and cleaning products as a surfactant. They are transformed in anaerobic waste water treatment plants to NP as an end product, which enters the environment via the sludges (Giger et al. 1984; Di Corcia et al. 1998). Nonylphenol exists of a mixture of isomers with a hydrophilic phenol group and a linear (4-n-NP) or a branched (tNP) carbon chain with nine carbon atoms (Fig. 1). Due to its chemical properties, it adsorbs to and accumulates in sediment (Sturm 1973; Kravetz 1983) as observed in river sediments in, e.g. Spain, Germany and Taiwan (Ding et al. 1999; Fries and Püttmann 2003; Navarro-Ortega et al. 2010). Since NP is an endocrine disruptor, degradation of NP in the sediment to non toxic compounds is of great interest (Nimrod and Benson 1996). Biodegradation under aerobic conditions is well described, as reviewed by Corvini et al. (2006). However, anaerobic degradation of NP is of greater importance since sediments are mainly anaerobic (Middeldorp et al. 2003). So far, tNP seems to be persistent under anaerobic conditions for biodegradation (Ekelund et al. 1993; Hesselsoe et al. 2001). Anaerobic biodegradation of 4-n-NP by bacteria has only been reported in sediment from the Erren River in Taiwan (Chang et al. 2004) under sulphate reducing, methanogenic and nitrate reducing conditions, respectively. Anaerobic bacterial degradation of 4-n-NP in soil and sludge from a waste water treatment plant has also been mentioned and 4-n-NP degrading strains were closely related to Bacillus niacini, Bacillus cereus and Acinetobacter baumanni (Chang et al. 2005; Chang et al. 2007).Fig. 1

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.

Show MeSH