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Janet K. Jansson – One of the best experts on this subject based on the ideXlab platform.

  • novel 4 Chlorophenol degradation gene cluster and degradation route via hydroxyquinol in arthrobacter Chlorophenolicus a6
    Applied and Environmental Microbiology, 2005
    Co-Authors: Karolina Nordin, Janet K. Jansson, Maria Unell
    Abstract:

    Arthrobacter Chlorophenolicus A6, a previously described 4Chlorophenol-degrading strain, was found to degrade 4Chlorophenol via hydroxyquinol, which is a novel route for aerobic microbial degradation of this compound. In addition, 10 open reading frames exhibiting sequence similarity to genes encoding enzymes involved in Chlorophenol degradation were cloned and designated part of a Chlorophenol degradation gene cluster (cph genes). Several of the open reading frames appeared to encode enzymes with similar functions; these open reading frames included two genes, cphA-I and cphA-II, which were shown to encode functional hydroxyquinol 1,2-dioxygenases. Disruption of the cphA-I gene yielded a mutant that exhibited negligible growth on 4Chlorophenol, thereby linking the cph gene cluster to functional catabolism of 4Chlorophenol in A. Chlorophenolicus A6. The presence of a resolvase pseudogene in the cph gene cluster together with analyses of the G+C content and codon bias of flanking genes suggested that horizontal gene transfer was involved in assembly of the gene cluster during evolution of the ability of the strain to grow on 4Chlorophenol.

  • Degradation of 4Chlorophenol at low temperature and during extreme temperature fluctuations by Arthrobacter Chlorophenolicus A6.
    Microbial ecology, 2004
    Co-Authors: Agneta Backman, Janet K. Jansson
    Abstract:

    Low average temperatures and temperature fluctuations in temperate soils challenge the efficacy of microbial strains used for clean up of pollutants. In this study, we investigated the cold tolerance of Arthrobacter Chlorophenolicus A6, a microorganism previously shown to degrade high concentrations of 4Chlorophenol at 28°C. Luciferase activity from a luc-tagged derivative of the strain (A6L) was used to monitor the metabolic status of the population during 4Chlorophenol degradation. The A6L strain could degrade 200–300 μg mL−1 4Chlorophenol in pure cultures incubated at 5°C, although rates of degradation, growth and the metabolic status of the cells were lower at 5°C compared to 28°C. When subjected to temperature fluctuations between 5 and 28°C, A6L continued to degrade 4Chlorophenol and remained active. In soil microcosm experiments, the degradation rates were significantly faster the first week at 28°C, compared to 5°C. However, this difference was no longer seen after 7 days, and equally low 4Chlorophenol concentrations were reached after 17 days at both temperatures. During 4Chlorophenol degradation in soil, CFU and luciferase activity values remained constant at both 5 and 28°C. However, once most of the 4Chlorophenol was degraded, both values decreased by 1–1.5 logarithmic values at 28°C, whereas they remained constant at 5°C, indicating a high survival of the cells at low temperatures. Because of the ability of A. Chlorophenolicus A6 to degrade high concentrations of 4Chlorophenol at 5°C, together with its tolerance to temperature fluctuations and stress conditions found in soil, this strain is a promising candidate for bioaugmentation of Chlorophenol-contaminated soil in temperate climates.

  • impact of 4 Chlorophenol contamination and or inoculation with the 4 Chlorophenol degrading strain arthrobacter Chlorophenolicus a6l on soil bacterial community structure
    FEMS Microbiology Ecology, 2002
    Co-Authors: Cecilia Jernberg, Janet K. Jansson
    Abstract:

    The 4Chlorophenol-degrading strain, Arthrobacter Chlorophenolicus A6L (chromosomally tagged with the firefly luciferase gene, luc) was inoculated into 4Chlorophenol-contaminated soil to assess the impact of bioaugmentation with a biodegrading strain on the indigenous microbiota. Simultaneously, the impact of 4Chlorophenol alone, or inoculation with A. Chlorophenolicus into non-contaminated soil, was addressed. Using terminal restriction fragment length polymorphism (T-RFLP) several significant changes were detected in community fingerprint patterns obtained from soil microcosms treated under the different conditions. The relative abundances of some populations, as judged by the relative intensity of terminal restriction fragments, were significantly impacted by either 4Chlorophenol, A. Chlorophenolicus inoculation, or by a combination of both inoculation and 4Chlorophenol contamination. Some populations were significantly stimulated and others were significantly repressed when compared to control soil with no additions. For several peaks, the positive or negative impact imposed by the treatments increased over the 13-day incubation period. Some members of the bacterial community were specifically sensitive to A. Chlorophenolicus inoculation or to 4Chlorophenol contamination, whereas other populations remained relatively unaffected by any of the treatments. The A. Chlorophenolicus inoculum was also monitored by T-RFLP and was found to have a significantly higher relative abundance in soil contaminated with 4Chlorophenol. These results were substantiated by a high correlation to luciferase activity measurements and the number of colony forming units of the inoculum. Therefore, the A. Chlorophenolicus A6L population was positively stimulated by the presence of the 4Chlorophenol substrate (180 μg g−1 soil) that it catabolized during the first 8 days of the incubation period as a carbon and energy source. Together, these results demonstrate that specific populations in the soil bacterial community rapidly fluctuated in response to specific disturbances and the resulting shifts in the community may therefore represent an adjustment in community structure favoring those populations best capable of responding to novel stress scenarios.

Cecilia Jernberg – One of the best experts on this subject based on the ideXlab platform.

  • impact of 4 Chlorophenol contamination and or inoculation with the 4 Chlorophenol degrading strain arthrobacter Chlorophenolicus a6l on soil bacterial community structure
    FEMS Microbiology Ecology, 2002
    Co-Authors: Cecilia Jernberg, Janet K. Jansson
    Abstract:

    The 4Chlorophenol-degrading strain, Arthrobacter Chlorophenolicus A6L (chromosomally tagged with the firefly luciferase gene, luc) was inoculated into 4Chlorophenol-contaminated soil to assess the impact of bioaugmentation with a biodegrading strain on the indigenous microbiota. Simultaneously, the impact of 4Chlorophenol alone, or inoculation with A. Chlorophenolicus into non-contaminated soil, was addressed. Using terminal restriction fragment length polymorphism (T-RFLP) several significant changes were detected in community fingerprint patterns obtained from soil microcosms treated under the different conditions. The relative abundances of some populations, as judged by the relative intensity of terminal restriction fragments, were significantly impacted by either 4Chlorophenol, A. Chlorophenolicus inoculation, or by a combination of both inoculation and 4Chlorophenol contamination. Some populations were significantly stimulated and others were significantly repressed when compared to control soil with no additions. For several peaks, the positive or negative impact imposed by the treatments increased over the 13-day incubation period. Some members of the bacterial community were specifically sensitive to A. Chlorophenolicus inoculation or to 4Chlorophenol contamination, whereas other populations remained relatively unaffected by any of the treatments. The A. Chlorophenolicus inoculum was also monitored by T-RFLP and was found to have a significantly higher relative abundance in soil contaminated with 4Chlorophenol. These results were substantiated by a high correlation to luciferase activity measurements and the number of colony forming units of the inoculum. Therefore, the A. Chlorophenolicus A6L population was positively stimulated by the presence of the 4Chlorophenol substrate (180 μg g−1 soil) that it catabolized during the first 8 days of the incubation period as a carbon and energy source. Together, these results demonstrate that specific populations in the soil bacterial community rapidly fluctuated in response to specific disturbances and the resulting shifts in the community may therefore represent an adjustment in community structure favoring those populations best capable of responding to novel stress scenarios.

  • Impact of 4Chlorophenol contamination and/or inoculation with the 4Chlorophenol‐degrading strain, Arthrobacter Chlorophenolicus A6L, on soil bacterial community structure
    FEMS microbiology ecology, 2002
    Co-Authors: Cecilia Jernberg, Janet K. Jansson
    Abstract:

    The 4Chlorophenol-degrading strain, Arthrobacter Chlorophenolicus A6L (chromosomally tagged with the firefly luciferase gene, luc) was inoculated into 4Chlorophenol-contaminated soil to assess the impact of bioaugmentation with a biodegrading strain on the indigenous microbiota. Simultaneously, the impact of 4Chlorophenol alone, or inoculation with A. Chlorophenolicus into non-contaminated soil, was addressed. Using terminal restriction fragment length polymorphism (T-RFLP) several significant changes were detected in community fingerprint patterns obtained from soil microcosms treated under the different conditions. The relative abundances of some populations, as judged by the relative intensity of terminal restriction fragments, were significantly impacted by either 4Chlorophenol, A. Chlorophenolicus inoculation, or by a combination of both inoculation and 4Chlorophenol contamination. Some populations were significantly stimulated and others were significantly repressed when compared to control soil with no additions. For several peaks, the positive or negative impact imposed by the treatments increased over the 13-day incubation period. Some members of the bacterial community were specifically sensitive to A. Chlorophenolicus inoculation or to 4Chlorophenol contamination, whereas other populations remained relatively unaffected by any of the treatments. The A. Chlorophenolicus inoculum was also monitored by T-RFLP and was found to have a significantly higher relative abundance in soil contaminated with 4Chlorophenol. These results were substantiated by a high correlation to luciferase activity measurements and the number of colony forming units of the inoculum. Therefore, the A. Chlorophenolicus A6L population was positively stimulated by the presence of the 4Chlorophenol substrate (180 μg g−1 soil) that it catabolized during the first 8 days of the incubation period as a carbon and energy source. Together, these results demonstrate that specific populations in the soil bacterial community rapidly fluctuated in response to specific disturbances and the resulting shifts in the community may therefore represent an adjustment in community structure favoring those populations best capable of responding to novel stress scenarios.

Ayse Kuleyin – One of the best experts on this subject based on the ideXlab platform.

  • removal of phenol and 4 Chlorophenol by surfactant modified natural zeolite
    Journal of Hazardous Materials, 2007
    Co-Authors: Ayse Kuleyin
    Abstract:

    In this study the adsorption characteristics of phenol and 4Chlorophenol by surfactant-modified zeolite was investigated. Batch studies were performed to evaluate the effects of various experimental parameters such as contact time, adsorbent dose, initial concentration, and temperature on the removal of phenol and 4Chlorophenol. The sorption kinetics was tested for intraparticle diffusion, Elovich, and pseudo-second order reaction and rate constants of kinetic models were calculated. Equilibrium isotherms for the adsorption of phenol were analyzed by Freundlich, Langmuir, and Tempkin isotherm models. Freundlich isotherm was found to best represent the data for phenol and 4Chlorophenol adsorption.