Abstract:
Acetaminophen (APAP) is the active ingredient of commonly used antipyretic and analgesic drugs; therefore it is one of the most frequently detected emerging micropollutant in the environment. In this study, four bacterial species capable of degrading APAP were isolated from soil microbial community developed by selective enrichment. Predominant APAP degrader in the community was a strain of Rhodococcus erythropolis. Other APAP degraders included strains of Pseudomonas nitroreducens, Flavobacterium sp., and Sphingobium sp. Among them the strains of Flavobacterium sp. and Sphingobium sp. are novel APAP-degraders, which have not been reported in the literature to date. A series of kinetic experiments in shake-flasks with Rhodococcus erythropolis BIOMIG-P19 were performed to evaluate the effect of APAP concentration, cell density and temperature on APAP biotransformation and to elucidate the APAP biotransformation pathway. The maximum cell specific APAP utilization rate and half-saturation APAP concentration constants were calculated as 133 ± 7 x 10-11 mg/cell.hr and 211 ± 28 mg/L, respectively. Optimum APAP biotransformation temperature was calculated as 28°C. p-aminophenol was identified as the major biotransformation by-product using tandem mass spectroscopy. Complete utilization of APAP by immobilized enzymes of BIOMIG-P19 at 1.5 mg protein and 10 mg/L APAP concentration lasted 12 days.
