MENVM / Department of Ecology and Resource Management / Polychlorinated biphenyls (PCBs) are worldwide environmental pollutants which contaminate the environment through careless disposal practices and accidental spills or leakages from electrical transformers. These organic compounds are lipophilic chemicals soluble in fats, slightly soluble in water and readily bioaccumulated in the fatty tissues of fish, birds, animals and humans. The main objective of this study was to isolate and identify PCB degrading bacteria from PCB contaminated soils and test them for their degradation ability of PCBs in natural habitat conditions. Three bacteria species which comprise of Gram negative and Gram positive microorganisms were isolated and identified through biochemical tests, catalase tests, oxidase tests and morphological study and included Burkholderia cepacia, Pasteurella pneumotropica and Enterococcus faecalis. The results indicated that, there was an overall decrease of PCB concentration level and the readings ranged between -1.51 and -1.79 respectively for all the microorganisms. Enterococcus faecalis remove as much as 32% of PCBs in the contaminated soil samples. Whereas Pasteurella pneumotropica could remove 24% of PCBs, Burkholderia cepacia 21% of PCBs and the mixed culture removed 23%. Data showed that the 3 bacterial strains could tolerate high concentration of PCBs. The results provided the evidence that naturally occurring bacteria in soil contaminated with PCBs have the potential to degrade PCBs. Statistical analysis showed that there was a significant positive correlation between bacteria growth and treatment with a coefficient of (r) =0.1459 and p value <0.001.

Steroid hormones in testis play an important role in spermatogenesis, maintenance of the male reproductive tract, production of semen and the maintenance of secondary sex characteristics and libido. They are also discussed as a target for substances called endocrine disruptors (EDs). No complex study was conducted on evaluation of relationships between EDs and steroid spectrum in 2 biological fluids; seminal plasma and plasma. The aim of the PhD. thesis was to develop and validate a method for determination of bisphenol A (BPA) and steroid spectrum in plasma and seminal plasma and to shed more light into mechanisms of ED action and effects of BPA and polychlorinated biphenyls (PCBs) on human spermatogenesis and steroidogenesis. Two new liquid-chromatography mass spectrometry methods for determination of BPA and 11 steroids in plasma and seminal plasma were developed and validated. The methods were used for estimation of analyte concentrations in 191 men with a different degree of fertility. Concurrently, the levels of six congeners of PCBs, gonadotropins, selenium and zinc in plasma were estimated. Partial correlations adjusted for age and BMI were calculated to evaluate relationships between these analytes. Seminal BPA, but not plasma BPA, was negatively associated with sperm concentration...

Polychlorinated Biphenyls (PCB's) are organochlorine molecules which find various industrial and product applications. PCB's are of concern to biologists because they are toxic substances which have become global contaminants. They are also of concern to biologists and analytical chemists because they interfere with the determination of some organochlorine pesticide residues. PCB's were discovered to be environmental contaminants after they showed up as unidentified peaks in pesticide analysis using gas-liquid chromatography with an electron capture detector (GLC-EC). In the present experiment standard GLC-EC techniques were used to assay PCB's in Daphnia experimentally contaminated in the laboratory and in crayfish from the Willamette River. Daphnia were placed in water containing 0.1, 4, 50 or 100 parts per billion (ppb) PCB for 4 to 72 hours. There was no mortality in any of the experiments. The individual PCB compounds were apparently taken up equally, since relative peak heights were similar in the standard and the residues extracted from Daphnia. Final concentrations of PCB's in Daphnis ranged from 1200 times that of the water (at water concentrations of 100 ppb) to 104,000 times that of water (at water concentrations of 0.1 ppb). The lower concentrations used here approximate environmental PCB levels found in some areas of the U.S. and elsewhere. Assuming that chronic exposure to these lower concentrations would not strongly inhibit growth or reproduction of Daphnia,, the high biological magnification found here would suggest that Daphnia and related organisms may play an important role in the accumulation of PCB's in fresh water food webs. Digestive glands of crayfish taken from the Willamette River were analyzed for PCB's. Statistically significant regional differences were found in the concentrations of PCB's in these organisms in the lower Willamette Valley. Crayfish from the center of Portland have the highest residues (7 to 9 parts per million). A similar distribution has been previously reported for other urban areas. In the present investigation, however, the highest residues occurred in crayfish from the river at a point approximately in the center of the city itself, but two miles upstream from the major industrial areas. Thus, in this case, the major source of environmental contamination may have been released from manufactured goods (e.g., automobile tires, paints, etc.) rather than from industrial sewerage. I

PCBs are recalcitrant compounds of no known natural origin that persist in the environment despite their ban by the United States Environmental Protection Agency in 1979 due to negative health effects. Transport of PCBs from elastic sealants into concrete, brick, and granite structures has resulted in the need for a technology capable of removing these PCBs from the materials. This research investigated the use of a nonmetal treatment system (NMTS) and an activated metal treatment system (AMTS) for the remediation and degradation of PCBs from concrete, brick, and granite affixed with PCB-laden caulking. The adsorption of PCBs onto the components of concrete and the feasibility of ethanol washing were also investigated. NMTS is a sorbent paste containing ethanol, acetic acid, and fillers that was developed at the University of Central Florida Environmental Chemistry Laboratory for the in situ remediation of PCBs. Combining NMTS with magnesium results in an activated treatment system used for reductive dechlorination of PCBs. NMTS was applied to laboratory-prepared concrete as well as field samples by direct contact as well as by a novel sock-type delivery. The remediation of PCBs from field samples using NMTS and AMTS resulted in a 33-98% reduction for concrete, a 65-70% reduction for brick, and an 89% reduction in PCB concentration for granite. The limit of NMTS for absorption of Aroclor 1254 was found to be roughly 22,000 mg Aroclor 1254 per kg of treatment system or greater. The activated treatment system resulted in a 94% or greater degradation of PCBs after seven days with the majority of degradation occurring in the first 24 hours. The adsorption of PCBs to individual concrete components (hydrated cement, sand, crushed limestone, and crushed granite) was found to follow the Freundlich isotherm model with greater adsorption to crushed limestone and crushed granite compared to hydrated cement and iv sand. Ethanol washing was shown to decrease the concentration of laboratory-prepared concrete by 68% and the concentration of PCBs in the ethanol wash were reduced by 77% via degradation with an activated magnesium system.

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are common contaminants of sediment, soils and biological tissues. These compounds pose a significant risk to biological and ecosystem health and functioning due to these compounds being mutagenic, carcinogenic and are known to disrupt the endocrine system. The bioaccumulation and biomagnification potential that these compounds possess mean that they are capable of affecting the entire food chain and are not limited to the organisms that are directly in contact with the compounds Even though there has been an increase in the attention on identifying the presence and impacts that these compounds may have in South Africa, the level of attention is lower than what it is in other countries around the world. Although South Africa has guidelines in place for other pollutants, such as metals, there are no such guidelines in place to monitor PAHs and PCBs.. Industries are known to release both PAHs and PCBs, mainly from incomplete burning processes and the release of oils and fuels in the case of PAHs, and from heat transfer fluids in the case of PCBs. Durban Bay and surrounding areas of eThekwini, KwaZulu-Natal are highly industrialised with many aquatic systems, in which these contaminants are likely to deposit. The aim of this research was to determine the concentrations of these compounds by means of chemical analysis and additionally biological analysis, using the H4IIE-luc bioassay and compare these levels to international guideline levels. It was found that the concentrations of the 23 analysed PAHs were 6.5–3 235.6 ng.g-1 and the concentration of the PCBs analysed were 0–113.83 ng.g-1. Many sites were found to be in exceedance of the guideline limits, particularly in the harbour. Toxic equivalency factors (TEF) were used to gauge the toxic equivalency (TEQ) of the PAHs and PCBs that were found. The TEQs were generally low, and were below any guideline levels. The assay revealed the extract containing the PCBs had a bioassay equivalence (BEQ) of 0–93.54 pgTCDDeq. g-1 and the extract containing the PAHs of 0–776.08 pgTCDD-eq.g-1. With a proportion of the sites exceeding guideline limits. The BEQ results were two to three orders of magnitude greater than the TEQs calculated from the concentrations determined by the instrumental analysis, however, followed a similar trend. Additionally chemical analysis was not performed on a full suite of compounds that are able to elicit a response from the cells, which could be a reason why the BEQ and TEQ did not follow a similar trend among some of the samples. It would have been more beneficial to have performed chemical analysis on the 16 priority PAHs (as determined by the United States Environmental Protection Agency), the dioxin-like PCBs and polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDFs) which are all capable of eliciting a response from the cells and have TEF values. The areas that were most affected by contamination of these compounds was the harbour and surrounding canals, and there was point source contamination along the Umhlatuzana, Umbilo, and Amanzimnyana Rivers. All dl-PCBs should be chemically analysed at all the sample areas, as these cause adverse effects to biota. In addition to this, biota should be sampled to determine concentrations of the compounds to determine bioavailability and the degree of bioaccumulation in the food chain. Utilising biomarkers it would be possible to determine stresses of fish. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are common contaminants of sediment, soils and biological tissues. These compounds pose a significant risk to biological and ecosystem health and functioning due to these compounds being mutagenic, carcinogenic and are known to disrupt the endocrine system. The bioaccumulation and biomagnification potential that these compounds possess mean that they are capable of affecting the entire food chain and are not limited to the organisms that are directly in contact with the compounds Even though there has been an increase in the attention on identifying the presence and impacts that these compounds may have in South Africa, the level of attention is lower than what it is in other countries around the world. Although South Africa has guidelines in place for other pollutants, such as metals, there are no such guidelines in place to monitor PAHs and PCBs.. Industries are known to release both PAHs and PCBs, mainly from incomplete burning processes and the release of oils and fuels in the case of PAHs, and from heat transfer fluids in the case of PCBs. Durban Bay and surrounding areas of eThekwini, KwaZulu-Natal are highly industrialised with many aquatic systems, in which these contaminants are likely to deposit. The aim of this research was to determine the concentrations of these compounds by means of chemical analysis and additionally biological analysis, using the H4IIE-luc bioassay and compare these levels to international guideline levels. It was found that the concentrations of the 23 analysed PAHs were 6.5–3 235.6 ng.g-1 and the concentration of the PCBs analysed were 0–113.83 ng.g-1. Many sites were found to be in exceedance of the guideline limits, particularly in the harbour. Toxic equivalency factors (TEF) were used to gauge the toxic equivalency (TEQ) of the PAHs and PCBs that were found. The TEQs were generally low, and were below any guideline levels. The assay revealed the extract containing the PCBs had a bioassay equivalence (BEQ) of 0–93.54 pgTCDDeq. g-1 and the extract containing the PAHs of 0–776.08 pgTCDD-eq.g-1. With a proportion of the sites exceeding guideline limits. The BEQ results were two to three orders of magnitude greater than the TEQs calculated from the concentrations determined by the instrumental analysis, however, followed a similar trend. Additionally chemical analysis was not performed on a full suite of compounds that are able to elicit a response from the cells, which could be a reason why the BEQ and TEQ did not follow a similar trend among some of the samples. It would have been more beneficial to have performed chemical analysis on the 16 priority PAHs (as determined by the United States Environmental Protection Agency), the dioxin-like PCBs and polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDFs) which are all capable of eliciting a response from the cells and have TEF values. The areas that were most affected by contamination of these compounds was the harbour and surrounding canals, and there was point source contamination along the Umhlatuzana, Umbilo, and Amanzimnyana Rivers. All dl-PCBs should be chemically analysed at all the sample areas, as these cause adverse effects to biota. In addition to this, biota should be sampled to determine concentrations of the compounds to determine bioavailability and the degree of bioaccumulation in the food chain. Utilising biomarkers it would be possible to determine stresses of fish. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Après avoir pu développer une nouvelle méthode de déracémisation de biphényles iodés permettant, pour la première fois, d’influencer la diastéréosélectivité de la réaction de piégeage du réactif d’Andersen par dédoublement cinétique, nous avons obtenu de nombreuses informations et développé des méthodes permettant de lever différents verrous synthétiques pour accéder à des paires de Lewis frustrées basées sur le squelette biphénylique et portant simultanément ou non un groupement acide de Lewis et une base de Lewis. Par la fonctionnalisation de ces biphényles, nous avons pu accéder à de nouvelles biphénylphosphines énantiopures pouvant jouer le rôle de base de Lewis dans le domaine des paires de Lewis frustrées (FLP) mais aussi d'organocatalyseur nucléophile ou de ligand pour la catalyse organométallique. Différentes méthodes ont ensuite été (re)développées, pour accéder à des acides de Lewis : d'une part la synthèse de boranes par fonctionnalisation de sels d'organotrifluoroborate de potassium comme précurseurs polyvalents d’acides de Lewis chiraux et énantiopurs et d'autre part l’utilisation de silanes électrophiles. L’ensemble des informations et méthodes découlant de ce travail pourront être appliquées à la synthèse de molécules ambiphiles, nouvelles paires de Lewis atropo-frustrées. / After having developed a new method of deracemization of iodinated biphenyls allowing us, for the first time, to influence the diastereoselectivity of the trapping by the Andersen reagent, we have turned our attention to the use of this molecular scaffold in the design of new frustrated Lewis pairs bearing either a Lewis acidic group, a Lewis basic group or simultaneously both groups. We first accessed a new series of enantiopure biphenylphosphines that can find applications as Lewis base (including the field of frustrated Lewis pairs), as nucleophilic organocatalyst or as ligand in organometallic catalysis. Then, various methods were (re)developed to access chiral biphenyl-based Lewis acids: firstly, the functionalization of biphenyltrifluoroborate salts as chiral and enantiopure borane precursors and secondly the use of electrophilic silanes. The whole information and methodologies developed herein may be applied to the synthesis of new ambiphilic compounds as new atropo-frustrated Lewis pairs.

O grupo de organoclorados, Bifenilas Policloradas (PCBs) é de difícil degradação e persistente no meio ambiente, tendo sido associado a diversos problemas nos organismos devido ao potencial toxicológico. Biodegradação constitui uma ferramenta eficaz e barata para remoção destes contaminantes do ambiente. O isolado RHA1 (fcb) de Rhodococcus sp. foi geneticamente construído com a introdução do operon de degradação hidrolítica de 4-clorobenzoato (fcb) para evitar a formação de produtos tóxicos durante a degradação de ácidos clorobenzóicos. Com o intuito de se obter informações sobre o processo adaptativo do recombinante Rhodococcus sp. isolado RHA1 (fcb) em substratos contendo PCBs, foram feitos dois ensaios avaliando-se a sobrevivência e o crescimento deste isolado. Rhodococcus sp. isolado RHA1 (fcb) foi inoculado (104 células.g-1) em substrato turfoso previamente irradiado a 50 KGy, contendo ou não 200 mg.Kg-1 de bifenilo. Em outro ensaio, além do recombinante, as bactérias Escherichia coli e Arthrobacter sp. foram inoculados em sedimento coletado na região do Estuário de Santos, contendo PHAs e PCBs, também irradiado (50 KGy). O crescimento das bactérias em ambos os substratos foi monitorado através de contagem de Unidades Formadoras de Colônias (UFCs). Algumas colônias eram selecionadas aleatoriamente para extração de DNA, detecção do operon fcb através de amplificação por PCR e sequenciamento do gene 16S rRNA. Aumento no número de UFCs nos tratamentos inoculados com o recombinante foi observado até 150 dias no ensaio com substrato turfoso e 70 dias na amostra ambiental. Entretanto, houve queda no número de UFCs após os 10 dias nos tratamentos inoculados com E. coli e Arthrobacter sp. Os genes fcbA e fcbB do operon fcb foram detectados nas colônias isoladas dos tratamentos inoculados com o isolado RHA1 (fcb) em ambos os substratos. A análise das seqüências pertencentes às colônias isoladas do tratamento inoculado com o isolado RHA1 (fcb) feita através de BLAST nos sites do NCBI e Ribossomal Database Project, apresentou 99% de identidade com a seqüência do gene ribossomal 16S de Rhodococcus sp. isolado ZC–3 (AM076672.1). Somente as seqüências referentes ao tratamento inoculado com E. coli foram analisadas, as quais apresentaram 99% de identidade com a seqüência do gene ribossomal 16S de E. coli isolado K-12 MG 1655 (U00096.2). Estes resultados sugerem que Rhodococcus sp. isolado RHA1 (fcb) cresce na turfa irradiada (até 150 dias) na presença e ausência de PCB e nesta amostra de sedimento irradiada (até 70 dias), com aparente estabilidade do operon fcb durante este período e nestas condições. A possível presença dos genes fcbB e fcbA em bactérias nativas crescidas em meio K1 com ácido 4- clorobenzóico isoladas do sedimento antes da irradiação, sugere a presença de bactérias do local com potencial biodegradador deste composto. / The group of organochlorates Biphenyl Polychlorates (PCBs) is of difficult degradation and persistent in the environment, being associated to several problems in the organisms due to its toxicological potential. The isolate RHA1 (fcb) from Rhodococcus sp. was genetically built with the introduction of the operon of hydrolytic degradation 4-chlorobenzoate (fcb) to avoid the formation of toxic products during the degradation of chlorobenzoic acids. In order to obtain information about the adaptative process of the recombinant Rhodococcus sp. isolate RHA1 (fcb) in substrates containing PCBs, two essays were made evaluating the survival and growth of this isolate. Rhodococcus sp. isolate RHA1 (fcb) was inoculated (104 cells.g-1) in peat substrate previously irradiated with 50 kGy, with and without 200 mg.kg-1 of biphenyl. In another essay, besides of the recombinant, the bacteria Escherichia coli and Arthrobacter sp. were inoculated in soil, also irradiated (50 kGy), from the Estuário de Santos region containing PHAs and PCBs. The growth of the bacteria in both substrates was monitorated counting the Colony Forming Units (CFUs). Some colonies were selected randomly for DNA extraction, fcb operon detection through PCR, and sequencing of the 16S rRNA gene. Rising in the number of CFUs in the recombinant inoculated treatments was observed until 150 days in the essay with peat substrate, and until 70 days in the environmental sample. Nonetheless, there was a reduction in the number of CFUs after 10 days in the treatment inoculated with E. coli and Arthrobacter sp. The genes fcbA and fcbB from the operon fcb were detected in the isolated colonies of the treatments inoculated with the isolate RHA1 (fcb) in both substrates. The analysis of the sequences belonging to the colonies isolated from the treatment inoculated with the isolate RHA1 (fcb) through BLAST in the NCBI and Ribosomal Database Project sites showed 99% identity with the sequence of the gene 16S ribosomal from Rhodococcus sp. isolate ZC-3 (AM076672.1). Only the sequences referring to the treatment inoculated with E. coli were analyzed, which showed 99% identity with the sequence of the 16S ribosomal gene from E. coli isolate K-12 MG 1655 (U00096.2). These results suggest that Rhodococcus sp. isolate RHA1 (fcb) grows in the peat irradiated (until 150 days), in the presence and absence of PCB and in this irradiated sediment sample (until 70 days), with apparent stability of the fcb operon during this period and in these conditions. The possible presence of the fcbA and fcbB genes in native bacteria grown in K1 medium with 4-chlorobenzoate acid isolated from sediment before irradiation suggests the presence of native bacteria with biodegradation potential of this compound.

O grupo de organoclorados, Bifenilas Policloradas (PCBs) é de difícil degradação e persistente no meio ambiente, tendo sido associado a diversos problemas nos organismos devido ao potencial toxicológico. Biodegradação constitui uma ferramenta eficaz e barata para remoção destes contaminantes do ambiente. O isolado RHA1 (fcb) de Rhodococcus sp. foi geneticamente construído com a introdução do operon de degradação hidrolítica de 4-clorobenzoato (fcb) para evitar a formação de produtos tóxicos durante a degradação de ácidos clorobenzóicos. Com o intuito de se obter informações sobre o processo adaptativo do recombinante Rhodococcus sp. isolado RHA1 (fcb) em substratos contendo PCBs, foram feitos dois ensaios avaliando-se a sobrevivência e o crescimento deste isolado. Rhodococcus sp. isolado RHA1 (fcb) foi inoculado (104 células.g-1) em substrato turfoso previamente irradiado a 50 KGy, contendo ou não 200 mg.Kg-1 de bifenilo. Em outro ensaio, além do recombinante, as bactérias Escherichia coli e Arthrobacter sp. foram inoculados em sedimento coletado na região do Estuário de Santos, contendo PHAs e PCBs, também irradiado (50 KGy). O crescimento das bactérias em ambos os substratos foi monitorado através de contagem de Unidades Formadoras de Colônias (UFCs). Algumas colônias eram selecionadas aleatoriamente para extração de DNA, detecção do operon fcb através de amplificação por PCR e sequenciamento do gene 16S rRNA. Aumento no número de UFCs nos tratamentos inoculados com o recombinante foi observado até 150 dias no ensaio com substrato turfoso e 70 dias na amostra ambiental. Entretanto, houve queda no número de UFCs após os 10 dias nos tratamentos inoculados com E. coli e Arthrobacter sp. Os genes fcbA e fcbB do operon fcb foram detectados nas colônias isoladas dos tratamentos inoculados com o isolado RHA1 (fcb) em ambos os substratos. A análise das seqüências pertencentes às colônias isoladas do tratamento inoculado com o isolado RHA1 (fcb) feita através de BLAST nos sites do NCBI e Ribossomal Database Project, apresentou 99% de identidade com a seqüência do gene ribossomal 16S de Rhodococcus sp. isolado ZC–3 (AM076672.1). Somente as seqüências referentes ao tratamento inoculado com E. coli foram analisadas, as quais apresentaram 99% de identidade com a seqüência do gene ribossomal 16S de E. coli isolado K-12 MG 1655 (U00096.2). Estes resultados sugerem que Rhodococcus sp. isolado RHA1 (fcb) cresce na turfa irradiada (até 150 dias) na presença e ausência de PCB e nesta amostra de sedimento irradiada (até 70 dias), com aparente estabilidade do operon fcb durante este período e nestas condições. A possível presença dos genes fcbB e fcbA em bactérias nativas crescidas em meio K1 com ácido 4- clorobenzóico isoladas do sedimento antes da irradiação, sugere a presença de bactérias do local com potencial biodegradador deste composto. / The group of organochlorates Biphenyl Polychlorates (PCBs) is of difficult degradation and persistent in the environment, being associated to several problems in the organisms due to its toxicological potential. The isolate RHA1 (fcb) from Rhodococcus sp. was genetically built with the introduction of the operon of hydrolytic degradation 4-chlorobenzoate (fcb) to avoid the formation of toxic products during the degradation of chlorobenzoic acids. In order to obtain information about the adaptative process of the recombinant Rhodococcus sp. isolate RHA1 (fcb) in substrates containing PCBs, two essays were made evaluating the survival and growth of this isolate. Rhodococcus sp. isolate RHA1 (fcb) was inoculated (104 cells.g-1) in peat substrate previously irradiated with 50 kGy, with and without 200 mg.kg-1 of biphenyl. In another essay, besides of the recombinant, the bacteria Escherichia coli and Arthrobacter sp. were inoculated in soil, also irradiated (50 kGy), from the Estuário de Santos region containing PHAs and PCBs. The growth of the bacteria in both substrates was monitorated counting the Colony Forming Units (CFUs). Some colonies were selected randomly for DNA extraction, fcb operon detection through PCR, and sequencing of the 16S rRNA gene. Rising in the number of CFUs in the recombinant inoculated treatments was observed until 150 days in the essay with peat substrate, and until 70 days in the environmental sample. Nonetheless, there was a reduction in the number of CFUs after 10 days in the treatment inoculated with E. coli and Arthrobacter sp. The genes fcbA and fcbB from the operon fcb were detected in the isolated colonies of the treatments inoculated with the isolate RHA1 (fcb) in both substrates. The analysis of the sequences belonging to the colonies isolated from the treatment inoculated with the isolate RHA1 (fcb) through BLAST in the NCBI and Ribosomal Database Project sites showed 99% identity with the sequence of the gene 16S ribosomal from Rhodococcus sp. isolate ZC-3 (AM076672.1). Only the sequences referring to the treatment inoculated with E. coli were analyzed, which showed 99% identity with the sequence of the 16S ribosomal gene from E. coli isolate K-12 MG 1655 (U00096.2). These results suggest that Rhodococcus sp. isolate RHA1 (fcb) grows in the peat irradiated (until 150 days), in the presence and absence of PCB and in this irradiated sediment sample (until 70 days), with apparent stability of the fcb operon during this period and in these conditions. The possible presence of the fcbA and fcbB genes in native bacteria grown in K1 medium with 4-chlorobenzoate acid isolated from sediment before irradiation suggests the presence of native bacteria with biodegradation potential of this compound.

No description available.