DEGRADATION OF NONIONIC SURFACTANTS AND POLYCHLORINATED-BIPHENYLS BY RECOMBINANT FIELD APPLICATION VECTORS

Degradation of polychlorinated biphenyls (PCBs) in the environment is limited by their aqueous solubility and the degradative competence of indigenous populations, Field application vectors (FAVs) have been dev eloped in which surfactants are used to both increase the solubility o f the PCBs and support the growth of surfactant-degrading strains engi neered for PGB degradation. Surfactant and PCB degradation by two reco mbinant strains were investigated, Pseudomonas putida IPL5 utilizes bo th alkylethoxylate [polyoxyethylene 10 lauryl ether (POL)] and alkylph enolethoxylate [Igepal CO-720 (IGP)] surfactants as growth substrates, but only degrades the ethoxylate moiety. The resulting degradation pr oducts from the alkyl-and alkylphenolethoxylate surfactants were 2-(do decyloxy)ethanol and nonylphenoldiethoxylates, respectively. Ralstonia eutropha B30P4 grows on alkylethoxylate surfactants without the appea rance of solvent-extractable degradation products, It also degrades th e 2-(dodecyloxy)ethanol produced by strain IPL5 from the alkylethoxyla te surfactants. The extent of degradation of the alkylethoxylate surfa ctant (POL) was greater for strain IPL5 (90%) than for B30P4 (60%) as determined by the cobaltothiocyanate active substances method (CTAS), The recombinant strain B30P4::TnPCB grew on biphenyl, In contrast, the recombinant strain IPL5::TnPCB could not grow on biphenyl, and PCB de gradation was inhibited in the presence of biphenyl. The most extensiv e surfactant and PCB degradation was achieved by the use of both recom binant strains together in the absence of biphenyl, PCB (Aroclor 1242) and surfactant (POL) concentrations were reduced from 25 ppm and 2000 ppm, respectively, to 6.5 ppm and 225 ppm, without the accumulation o f surfactant degradation products, Given the inherent complexity of co mmercial surfactant preparations, the use of recombinant consortia to achieve extensive surfactant and PCB degradation appears to be an envi ronmentally acceptable and effective PCB remediation option.