Study On Cometabolic Degradation Of Chlorophenols By Pseudomonas Aeruginosa TBPY

Chlorophenols have been widely used as preservatives, disinfectants, pesticides and herbicides. These toxic chemicals are quite recalcitrant to degradation and can accumulate in the environment. In treatments for chlorophenols, the biological method has attracted more attention than physical and chemical methods because of relative inexpensive cost and less secondary pollution. However, the natural degradation of them is very difficult because of the stability of their structures. Co-metabolism is one of the most important methods for refractory organic compounds degradation. In this work, the degradation characters of chlorophenol with ethanol as growth substrate by a newly isolated strain Pseudomonas aeruginosa TBPY were reported.Firstly, the growth of Pseudomonas aeruginosa TBPY and the degradation performance of 4-chlorophenol were studied with the help of Vis-UV spectrophotometer and high performance liquid chromatography (HPLC). Results showed that the 4-chlorophenol-degrading capability of TBPY had increased greatly through acclimation. The highest endurance capability of TBPY was about 150mg·l-1 4-chlorophenol. The 4-chlorophenol degradation rate was over 99% in 1 day when 4-chlorophenol concentration was 100mg/l, the temperature was 30℃, degradation of cell was in the logarithmic phase, the start culture medium was 100ml the initial medium pH value was 8.0, the inoculation volume was 1.0～2.0%.Secondly, the degradation pathway of 4-CP was studied.The major metabolites of 4-chlorphenol were identified as with spectrophotometer, high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS).The study showed that the degradation of 4-CP led to formation of acyl-malay acetic acid and 4-alkenyl carbocisteine-2-butene-4-lactone, which were further metabolized, indicating complete degradation of 4-CP via a ortho-cleavage pathway.Moreover, enzyme tests revealed that the degradation of 4-CP occurred via an inducible ortho-cleavage pathway.Moreover, the mechanism of 4-CP concentration reply was also studied.Thirdly, the shape of TBPY before and after acclimation had changed greatly. TBPY before acclimation was neat, straight or slightly curved, blunt at both ends of a uniform circular rod-shaped. TBPY after acclimation was uneven, short rod and straight rod-shaped. Most of the bacterial after acclimation were peanut shell-like. Bacterial periphery was translucent .They had a good self-protection ability. In addition, TBPY showed bacterial aggregation behavior of self-protection in adverse enviroments.Fourthly, The highest endurance and degradation capability of TBPY about 2,4-DCP and 2,4,6-TCP were studied.The highest endurance capability of TBPY about 2,4-DCP and 2,4,6-TCP were 75mg/l and 175mg/l,respectively.Under the optimum 4-CP degradation conditions, the initial concentration of 2, 4-DCP was from 50mg/l to 20.96mg/l in 19 days, the degradation rate of 2, 4-DCP was 58.08%. And the initial concentration of 2, 4, 6-TCP was from 100mg/l to 0.36mg/l in 4days, the degradation rate of 2, 4, 6-TCP was above 99%.