Journal of Industrial Microbiology & Biotechnology (1997) 19 , 252–262  1997 Society for Industrial Microbiology 1367-5435/97/$12.00 Degradation of nonionic surfactants and polychlorinated biphenyls by recombinant field application vectors CA Lajoie, AC Layton, JP Easter, F-M Menn and GS Sayler Department of Microbiology and Department of Ecology and Evolutionary Biology, Center for Environmental Biotechnology, University of Tennessee, 676 Dabney Hall, Knoxville, Tennessee 37996-1605, USA 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 developed in which surfactants are used to both increase the solubility of the PCBs and support the growth of surfactant-degrading strains engineered for PCB degradation. Surfactant and PCB degradation by two recombinant strains were investi- gated. Pseudomonas putida IPL5 utilizes both alkylethoxylate [polyoxyethylene 10 lauryl ether (POL)] and alkylphenolethoxylate [Igepal CO-720 (IGP)] surfactants as growth substrates, but only degrades the ethoxylate moi- ety. The resulting degradation products from the alkyl- and alkylphenolethoxylate surfactants were 2- (dodecyloxy)ethanol and nonylphenoldiethoxylates, respectively. Ralstonia eutropha B30P4 grows on alkylethoxy- late surfactants without the appearance of solvent-extractable degradation products. It also degrades the 2- (dodecyloxy)ethanol produced by strain IPL5 from the alkylethoxylate surfactants. The extent of degradation of the alkylethoxylate surfactant (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 degradation was inhibited in the presence of biphenyl. The most extensive surfactant and PCB degradation was achieved by the use of both recombinant 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 of surfac- tant degradation products. Given the inherent complexity of commercial surfactant preparations, the use of recombi- nant consortia to achieve extensive surfactant and PCB degradation appears to be an environmentally acceptable and effective PCB remediation option. Keywords: alkylethoxylate; alkylphenolethoxylate; nonylphenoldiethoxylate; Pseudomonas putida; Ralstonia eutropha; gen- etically engineered microorganisms Introduction Considerable research has been conducted on the metab- olism and genetics of PCB degradation by naturally occur- Although surfactant degradation and the genetics of polych- ring microorganisms [2,5,6,11,15,16,18,19,28,36]. In many lorinated biphenyl (PCB) biodegradation may appear to be aerobic PCB-degrading bacteria, PCB degradation is co- disparate topics, potential technologies for soil remediation metabolic, and inducible by biphenyl. Although the genes have been proposed which employ soil washing and PCB for biphenyl/PCB degradation have been cloned, the regu- contaminant biodegradation. Surfactants can be used to lation of the biphenyl operon in potential recombinant increase the solubility of hydrophobic environmental con- strains and the compatibility of the biphenyl degradation taminants including PCBs [1,10,38] and have been applied pathway with existing pathways cannot always be predicted to soil washing or soil flushing technologies for soil reme- a priori [28]. diation [37]. Enhanced water solubility may result in the Field application vectors (FAVs), which are genetically enhanced bioavailability of contaminants to micro- engineered microorganisms capable of utilizing a selective organisms, although contradictory evidence has been carbon source and expressing foreign genes, have been con- reported [20]. Nonionic surfactants may be the most logical structed for use in the bioremediation of soils contaminated possibility for enhancing contaminant bioavailability as with PCBs [21–23]. Treatment approaches utilizing FAVs they are both effective at solubilizing contaminants and are use surfactants to both solubilize PCBs and support the generally less toxic to microorganisms than anionic or cat- growth of surfactant-degrading bacterial strains bioengin- ionic surfactants [35]. Since surfactants may be applied in eered for PCB degradation. Previous research with PCB- solutions of 0.5% and higher in soil-flushing technologies degrading FAVs focused on PCB degradation and did not [1,38], the surfactant-degradative activities of microbes examine the extent of surfactant degradation or the pro- may have important environmental consequences. duction of surfactant metabolites [22,23]. Whereas information is available from other studies on surfactant degradation in the environment and the genetics Correspondence: Dr CA Lajoie, Dept of Microbiology and Dept of Ecol- of PCB degradation, successful integration of these disci- ogy and Evolutionary Biology, Center for Environmental Biotechnology, plines into an effective and environmentally acceptable site University of Tennessee, 676 Dabney Hall, Knoxville, TN 37996-1605, remediation technology has not been achieved. The specific USA Received 4 October 1996; accepted 4 August 1997 objective of the work reported here was to further an