Project description:Mycobacterium dioxanotrophicus PH-06 can degrade 1,4-dioxane (dioxane), which is a groundwater contaminant of emerging concern. In order to find the genes involved in dioxane degradation. RNA sequencing was first used to investigate gene expression levels of PH-06 during growth on two different carbon sources (dioxane and glucose). The sequencing shows that a monooxygenase gene cluster was upregulated when treated with dioxane relative to glucose.
Project description:Membrane bioreactor (MBR) systems are typically known different from conventional activated sludge (CAS) systems in operational parameters, while current knowledge of their microbial differentiations is barely sufficient. To this end, the current study was launched to address the differences of the overall functional genes of an oxidation ditch (OD) and an MBR running parallelly at full-scale using a functional gene array-GeoChip 4.2. Two full-scale wastewater treatment systems applying the processes of oxidation ditch (OD) and membrane bioreactor (MBR) were investigated. They treated identical wastewater at the same scale. 12 mixed-liquor suspended sludge (MLSS) samples collected daily on 12 consecutive days from each system were analyzed by GeoChip 4.2.
Project description:We evaluated liver tissues of B6D2F1/Crl mice exposed to 0, 40, 200, 600, 2000, or 6000 ppm 1,4-dioxane in drinking water for 7, 28, or 90 days in support of an investigation of the mode of action for 1,4-dioxane-induced murine liver tumors. TempO-Seq technology was used to measure global hepatic gene expression. Exposure-induced transcriptional responses increased by dose and exposure duration, with few differentially expressed genes at 40 and 200 ppm regardless of exposure duration. Pathway enrichment analysis identified significant perturbations in pathways associated with xenobiotic metabolism, complement and coagulation cascades and fatty acid metabolism in 600, 2000, and 6000 ppm groups at all timepoints compared to time-matched control groups. A significant transcriptomic proliferative response was only observed in 6000 ppm exposed mice at 90 days. Differential gene expression and pathway enrichment analysis results suggest 600 ppm as a potential threshold concentration for hepatic transcriptomic response to 1,4-dioxane in female mice.
Project description:Bio-augmentation could be a promising strategy to improve processes for treatment and resource recovery from wastewater. In this study, the Gram-positive bacterium Bacillus subtilis was co-cultured with the microbial communities present in wastewater samples with high concentrations of nitrate or ammonium. Glucose supplementation (1%) was used to boost biomass growth in all wastewater samples. In anaerobic conditions, the indigenous microbial community bio-augmented with B. subtilis was able to rapidly remove nitrate from wastewater. In these conditions, B. subtilis overexpressed nitrogen assimilatory and respiratory genes including NasD, NasE, NarG, NarH, and NarI, which arguably accounted for the observed boost in denitrification. Next, we attempted to use the the ammonium- and nitrate-enriched wastewater samples bio-augmented with B. subtilis in the cathodic compartment of bioelectrochemical systems (BES) operated in anaerobic condition. B. subtilis only had low relative abundance in the microbial community, but bio-augmentation promoted the growth of Clostridium butyricum and C. beijerinckii, which became the dominant species. Both bio-augmentation with B. subtilis and electrical current from the cathode in the BES promoted butyrate production during fermentation of glucose. A concentration of 3.4 g/L butyrate was reached with a combination of cathodic current and bio-augmentation in ammonium-enriched wastewater. With nitrate-enriched wastewater, the BES effectively removed nitrate reaching 3.2 mg/L after 48 h. In addition, 3.9 g/L butyrate was produced. We propose that bio-augmentation of wastewater with B. subtilis in combination with bioelectrochemical processes could both boost denitrification in nitrate-containing wastewater and enable commercial production of butyrate from carbohydrate- containing wastewater, e.g. dairy industry discharges. These results suggest that B. subtilis bio-augmentation in our BES promotes simultaneous wastewater treatment and butyrate production.
Project description:To understand microbial community functional structures of activated sludge in wastewater treatment plants (WWTPs) and the effects of environmental factors on their structure, 12 activated sludge samples were collected from four WWTPs in Beijing. GeoChip 4.2 was used to determine the microbial functional genes involved in a variety of biogeochemical processes. The results showed that, for each gene category, such as egl, amyA, nir, ppx, dsrA sox and benAB, there were a number of microorganisms shared by all 12 samples, suggestive of the presence of a core microbial community in the activated sludge of four WWTPs. Variance partitioning analyses (VPA) showed that a total of 53% of microbial community variation can be explained by wastewater characteristics (25%) and operational parameters (23%), respectively. This study provided an overall picture of microbial community functional structures of activated sludge in WWTPs and discerned the linkages between microbial communities and environmental variables in WWTPs. Four full-scale wastewater treatment systems located in Beijing were investigated. Triplicate samples were collected in each site.
Project description:Over activation of the aryl hydrocarbon receptor (AhR) by TCDD results ampng other phenotypes in severe thymic atrophy accompanied by immunosuppression. The link between thymic atrophy, skewed thymocyte differntiation and immunosuppression is still not fully resolved. This study investigates the TCDD elicted exprssion changes in the ET, cortical thymus epithelial cell line. Keywords: TCDD, AhR, thymic epithelial cells, thymic involution, thymus atrophy ET cells were grown to 80-90% confluence and treated with 5nM TCDD or solvent control (1,4-Dioxane, 0,05%V). 2h,4h and 6h after treatment, RNA was isolated using TRIzol and gene expression measured. All experiments wer done in biological duplicates.