The effect of structure and a secondary carbon source on the microbial degradation of chlorophenoxy acids

• Published in: Chemosphere (Oxford) Vol. 79; no. 11; pp. 1084 - 1088
• Main Authors: Evangelista, S., Cooper, D.G., Yargeau, V.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-05-2010; Elsevier
• Subjects: 2,4-Dichlorophenoxyacetic Acid - analogs & derivatives; 2,4-Dichlorophenoxyacetic Acid - metabolism; 2-Methyl-4-chlorophenoxyacetic Acid - analogs & derivatives; 2-Methyl-4-chlorophenoxyacetic Acid - chemistry; 2-Methyl-4-chlorophenoxyacetic Acid - metabolism; Applied sciences; Aspergillus niger; Aspergillus niger - metabolism; Bacillus subtilis - metabolism; Biodegradation, Environmental; Bonding; Carbon; Carbon - chemistry; Carbon source; Chlorophenoxy acids; Clofibric acid; Clofibric Acid - chemistry; Clofibric Acid - metabolism; Cresols - chemistry; Degradation; Exact sciences and technology; Glucose; Glucose - metabolism; Metabolites; Microbial degradation; Microorganisms; Pollution; Pseudomonas; Pseudomonas - metabolism; Rhodococcus - metabolism; Ring opening; Sphingomonas - metabolism; Niger; Africa; Carbon source; Clofibric acid; Chlorophenoxy acids; Microbial degradation; Pseudomonadales; Biodegradation; Bacillus subtilis; Pollutant behavior; Metabolite; Steric hindrance; Bacillaceae; Pseudomonas; Fungi; Aspergillus; Bacillales; Bacteria; Pseudomonadaceae; Fungi Imperfecti; Degradation product
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2010.03.018

Pseudomonas putida, Aspergillus niger, Bacillus subtilis, Pseudomonas flourescens, Sphingomonas herbicidovorans and Rhodococcus rhodochrous growing on glucose in a medium containing one of three chlorophenoxy acids at a concentration of 0.1
g
L
−1 (clofibric acid, (
R)-2-(4-chloro-2-methylphenoxy)propionic acid (mecoprop or MCPP) and 4-chloro-2-methylphenoxyacetic acid (MCPA)) degraded these compounds to varying degrees; from nonmeasurable to almost complete removal. These results with the addition of glucose (2.5
g
L
−1) as an easy to use carbon source indicated the formation of metabolites different from results reported in the literature for growth studies in which the chlorophenoxy acid was the sole carbon source. The metabolite, 4-chloro-2-methylphenol, which had been reported previously, was only observed in trace amounts for MCPP and MCPA in the presence of
S. herbicidovorans and glucose. In addition, three other compounds (M1, M3 and M4) were observed. It is suggested that these unidentified metabolites resulted from ring opening of the metabolite 4-choloro-2-methylphenol (M2).
The rate of biodegradation of the chlorophenoxy acids was influenced by the degree of steric hindrance adjacent to the internal oxygen bond common to all three compounds. The most hindered compound, clofibric acid, was converted to ethyl clofibrate by
R. rhodochrous but was not degraded by any microorganisms studied. The more accessible internal oxygen bonds of the other two chlorophenoxy acids, MCPP and MCPA, were readily broken by
S. herbicidovorans.