Degradation of Triclosan under Aerobic, Anoxic, and Anaerobic Conditions

Abstract

Triclosan (2, 4, 4'-trichloro-2'-hydroxyl diphenyl ether) is a broad-spectrum antimicrobial agent present in a number of house hold consumables. Aerobic and anaerobic enrichment cultures tolerating triclosan were developed and 77 bacterial strains tolerating triclosan at different levels were isolated from different inoculum sources. Biodegradation of triclosan under aerobic, anoxic (denitrifying and sulphate reducing conditions), and anaerobic conditions was studied in batch cultures with isolated pure strains and enrichment consortium developed. Under aerobic conditions, the isolated strains tolerated triclosan up to 1 g/L and degraded the compound in inorganic-mineral-broth and agar media. At 10 mg/L level triclosan, 95 ± 1.2% was degraded in 5 days, producing phenol, catechol and 2, 4-dichlorophenol as the degradation products. The strains were able to metabolize triclosan and its degradation products in the presence of monooxygenase inhibitor 1-pentyne. Under anoxic/anaerobic conditions highest degradation (87%) was observed in methanogenic system with acetate as co-substrate and phenol, catechol, and 2, 4-dichlorophenol were among the products. Three of the isolated strains tolerating 1 g/L triclosan were identified as Pseudomonas sp. (BDC 1, 2, and 3).

Removal of Pharmaceuticals and Personal Care Products during Water Recycling: Microbial Community Structure and Effects of Substrate Concentration

“…denitrificans TR1 (51), Pseudomonas putida TriRY (52), Nitrosomonas europaea (53), and Pseudomonas sp. BDC1, -2, and -3 (GQ456128, GQ456129, and GQ456130, respectively) (54).…”

Identification of triclosan-degrading bacteria using stable isotope probing, fluorescence in situ hybridization and microautoradiography

“…Previous studies have shown the ability of a few isolates to degrade triclosan (Gangadharan Puthiya Veetil et al, 2012;Hay et al, 2001;Kim et al, 2011;Meade et al, 2001). However, as these studies rely on the use of culture-dependent methods and do not necessarily reflect the identity of the active members involved in the biodegradation of triclosan in situ, the focus of this study was to apply SIP to identify bacteria capable of utilizing triclosan in an enrichment culture.…”

“…Metabolic pathway analyses have shown that Methylobacillus contains unique clusters of genes encoding the degradation of chlorocatechol, a major intermediate product in the biodegradation of chloroaromatic compounds (Caspi et al, 2012;Spokes & Walker, 1974). Little information is available regarding the biodegradation products of triclosan, although catechol and 3,5-dichlorocatechol were detected when triclosan was degraded by pure cultures of Pseudomonas-like strains (Gangadharan Puthiya Veetil et al, 2012) and Sphingomonas sp. PH-07 incubated with diphenyl ether (Kim et al, 2011).…”

“…Biodegradation of triclosan has been shown by mixed bacterial cultures from activated sludge (Gangadharan Puthiya Veetil et al, 2012;Hay et al, 2001;Stasinakis et al, 2010) and in wastewater treatment plants (WWTPs) (Bester, 2003;Chen et al, 2011;Singer et al, 2002). Due to insufficient removal during wastewater treatment, triclosan has been found in WWTP effluents in concentrations ranging from 1 to 10 mg l 21 (Adolfsson-Erici et al, 2002;Bester, 2003Bester, , 2005Lindström et al, 2002;Singer et al, 2002).…”

“…Meade et al (2001) showed that two soil bacteria, Pseudomonas putida and Alcaligenes xylosoxidans, have a high resistance to triclosan and can utilize it as their sole carbon source, and the nitrifying Nitrosomonas europea has also been shown to biodegrade triclosan (Roh et al, 2009). Recently, several triclosan-degrading strains belonging to the genus Pseudomonas were isolated from aerobic and anaerobic enrichment cultures of activated sludge (Gangadharan Puthiya Veetil et al, 2012). Biodegradation of triclosan has also been reported in fungi (Hundt et al, 2000).…”