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Five bioassays were used to measure toxicity during bioremediation of a soil contaminated with pentachlorophenol (PCP; 335 ppm), polycyclic aromatic hydrocarbons (PAHs; 1225 ppm) and petroleum hydrocarbons (19 125 ppm). Different bioremediation treatments were tested in soilmicrocosms including amendment with phosphorus and/or PCP-degrading Pseudomonas sp. UG30, either as free cells or encapsulated in k-carrageenan. Soil toxicity was monitored using the solid-phase Microtox test, SOS-chromotest, lettuce seed germination, earthworm survival and sheep red blood cell (RBC) haemolysis assays. PCP levels were reducedin all treatments after 210 days. The RBC lysis assay, Microtox testand SOS-chromotest indicated reduced toxicity in most of the microcosms by day 210. Trends depicted by lettuce seed germination and earthworm survival LC50 values varied with each treatment. For example, insoil amended with phosphorus, both the seed germination and earthworm survival LC50 data suggested increased soil toxicity. However, for soil treated with encapsulated Pseudomonas sp. UG30 cells, the earthworm survival LC50 data indicated reduced toxicity while seed germination LC50 values showed little change from values obtained prior to bioremediation. Our results show that toxicity trends in a contaminatedsoil during bioremediation differ according to the assay used. [ABSTRACT FROM AUTHOR]

In this opinion paper, we offer our perspective on our bioremediation research along with the methods to assess its effectiveness as a safe and beneficial technology to remediate selected soil sites. The isolation and characterization of bacterial isolates from chemically contaminated soils, their survival and catabolic activity in contaminated soil, toxicity testing in chemically contaminated soils, molecular-based methods of detection such as the polymerase chain reaction (PCR) and DNA probing are discussed. By using numerous conventional microbiological, chemical techniques, and molecular based methods, bioremediation can be studied in a comprehensive manner and the technology transferred to the commercial sector. [ABSTRACT FROM AUTHOR]

Escherichia coli lacZ strains CC107-CC111, which detect specific frameshift mutations, were used to study the mutational specificities of 2-nitro-3-methylimidazo[4,5-f] quinoline (NO2-IQ) and rat hepatic S9-activated 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). New constructs were made in which UvrABC-dependent excision repair was eliminated (strains DJ3107-DJ3111), followed by introduction of plasmid pYG219 conferring acetyl CoA:arylamine N-acetyltransferase/acetyl CoA:arylhydroxylamine O-acetyltransferase (NAT/OAT) activity (strains DJ3207-DJ3211). Sensitivity to mutagens was greatly enhanced. The mutational specificity of NO2-IQ was identical to that of the corresponding amine, IQ. The most prominent mutations caused by the two compounds were -2(CGGC) and 1(CG) frameshifts. +1(AT) Frameshifts play a minor role in the pattern of mutational specificity. Induction of all three mutations was similarly influenced by NAT/OAT activation and UvrABC-dependent excision repair. These new tester strains provide an effective tool for the study of aromatic amine mutational specificity and the influences of excision repair and NAT/OAT activation.