.2,4 - Dichlorophenol Microbial Degradation And Related Genes

Two 2,4-dichlorophenol degrading bacteria strains, designated as GT24 1-1 and GT 141-2 respectively, were isolated from the soil around drainage area of several factories which produced 2,4-dichlorophenol . They were identified as Pseudomonas sp. At 25~300C, strain GT241-1 can decompose 2,4-dichlorophenol from 60-400 mg/L to 8-42 mgIL within 48 hours, and strain GT141-2 can decompose 2,4- dichlorophenol from 60-400 mg/L to 25--30 mg/L within 36 hours. GC/MS analysis revealed that they can degrade 2,4-dichlorophenol completely, without accumulation of intermediate metabolite. Heat treatment at 380C made 1.9% of strain GT241-1 lose its 2,4-dichlorophenol degrading ability. Besides 2,4-dichlorophenol, strain GT241-l can also utilize 2,4-D and benzoate as sole carbon and energy source, and strain GT141-2 can also utilize benzoate as sole carbon and energy source, but they cannot utilize salicylate, 2-chlorobenzoate, 4-chlorobenzoate, 2,4,6-trichlorophenol and pentachlorophenol as as sole carbon and energy source. Strain GT241-1 and GT141-2 have two and three big plasmids respectively. Southern blot showed that the 3,5- dichlorocatechol 1,2-dioxygenase gene of strain GT141-2 locates on its smallest plasmid. The active sludge from a pesticide plant adapted to 2,4-dichlorophenol and gained the 2,4-dichlorophenol degrading ability after three months acclimation. The acclimated sludge were used to treated imitate waste water of 60 mg/L 2,4- dichlorophenol and 1500 mgIL COD after being added 0.59% or 1.18% of strain GT241-1. The result showed that they have the same ability for degrading 2,4- dichlorophenol, and can decompose 2,4-dichlorophenol to the lowest value of 9 mg/L within 20 hours while the active sludge without adding strain GT241-1 need 30 hours. So compared with the active sludge without adding strain GT24 1-1, the active sludge with strain 0T241-1 can decompose 2,4-dichlorophenol more rapidly. The active sludge with or without adding strain GT241-1 can decompose 2,4-dichlorophenol from 60-.~70 mg/L to 9-43 mg/L within 20 hours and 30 hours respectively in the batch treatment. Upto the fifth round, the decomposition effect of strain GT241-1 can be seen. When provided dissolved oxygen within 5.6?.4 mg/L by pump, the active sludge with or without adding strain GT241-1 didn抰 show different degrading ability. When added strain GT241-1, the active sludge bioreactor can start up more rapidly. When loaded imitate waste water of 60 mg/L 2,4-dichlorophenol and 1500 mg/L COD with HRT 63h or 32h, the 2,4-dichlorophenol concentration in the effluent water of the bioreactor with or without strain GT24 1-1 is the same, 11.0 mg/L. Later when loaded the same imitate waste water with HRT 20h, the effluent water showed 102 difference, the 2,4-dichlorophenol concentration in the effluent water of the bioreactor with or without strain GT24 1-1 is 11.2 mg/L and 16.7 mg/L respectively. When loaded imitate waste water of 100 mgIL 2,4-dichlorophenol and 1500 mg/L COD with HRT 32h, the 2,4-dichlorophenol concentration in the effluent water of the bioreactor with or without strain GT241-1 is 19.4 mgIL and 30.6 mgIL respectively, and the effluent water are all turbid. 87%?0% COD can be removed during the treatment. Southern blot showed that 2,4-dichlorophenol hydroxylase gene(dcpA) of strain GT241-1 locates on the about 10kb EcoRI/XbaI fragment. This fragment was recovered, linked to the vecter pUC 19 and transformed into the E. coil DH5ct~. A aim transforman...