title: Inhibition of p-cresol on aerobic biodegradation of carbazole, and sodium salicylate by Pseudomonas putida.
abstract: A PAH- and phenol-degrading microorganism, Pseudomonas putida (ATCC 17484), was used to study the substrate interactions during cell growth on carbazole-containing mixtures with p-cresol and sodium salicylate. Both p-cresol and sodium salicylate could be utilised by the bacteria as the sole carbon and energy sources. When cells grew on the mixture of carbazole, p-cresol and sodium salicylate, strong substrate interactions were observed. Carbazole degradation started only after p-cresol was significantly or completely removed, and the removal of carbazole was incomplete when the initial p-cresol concentration was higher than 20 mg/l. No carbazole was removed at all when the initial p-cresol concentration in the system was higher than 120 mg/l. When cells grew on the ternary substrates, the specific growth rate was found to increase with p-cresol concentration up to 50 mg/l (from 0.33 to 0.45 h(-1)) but decreased monotonically with higher concentrations. At 120 mg/l p-cresol, specific growth rate fell to 0.33 h(-1). The inhibitory effect of p-cresol was demonstrated where carbazole degradation was immediately halted when 50 mg/l p-cresol was spiked to a system containing carbazole and sodium salicylate. Besides, the addition of p-cresol was also found to inhibit the degradation of sodium salicylate. With p-cresol, an increase in lag time was observed and the utilisation of sodium salicylate as carbon source was severely retarded.
authors.affiliation: Department of Chemical and Environmental Engineering, The National University of Singapore, Singapore.
authors.forename: Yue-Gen
authors.initials: YG
authors.lastname: Yu
authors.forename: Kai-Chee
authors.initials: KC
authors.lastname: Loh
mesh_terms: D001420:Bacteria, Aerobic / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D001673:Biodegradation, Environmental / Q000187:drug effects; D002227:Carbazoles / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D003408:Cresols / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D016958:Pseudomonas putida / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D012980:Sodium Salicylate / Q000378:metabolism*; D013997:Time Factors; D018508:Water Purification
chemical_list: D002227:Carbazoles; D003408:Cresols; C041514:carbazole; C032538:4-cresol; D012980:Sodium Salicylate