Project description:Manufactured nanomaterials (MNMs) are increasingly incorporated into consumer products that are disposed into sewage. In wastewater treatment, MNMs adsorb to activated sludge biomass where they may impact biological wastewater treatment performance, including nutrient removal. Here, we studied MNM effects on bacterial polyhydroxyalkanoate (PHA), specifically polyhydroxybutyrate (PHB), biosynthesis because of its importance to enhanced biological phosphorus (P) removal (EBPR). Activated sludge was sampled from an anoxic selector of a municipal wastewater treatment plant (WWTP), and PHB-containing bacteria were concentrated by density gradient centrifugation. After starvation to decrease intracellular PHB stores, bacteria were nutritionally augmented to promote PHB biosynthesis while being exposed to either MNMs (TiO2 or Ag) or to Ag salts (each at a concentration of 5 mg L-1). Cellular PHB concentration and PhyloChip community composition were analyzed. The final bacterial community composition differed from activated sludge, demonstrating that laboratory enrichment was selective. Still, PHB was synthesized to near-activated sludge levels. Ag salts altered final bacterial communities, although MNMs did not. PHB biosynthesis was diminished with Ag (salt or MNMs), indicating the potential for Ag-MNMs to physiologically impact EBPR through the effects of dissolved Ag ions on PHB producers. 18 samples; Triplicate PHB-enriched bacterial communities recovered from activated sludge were exposed to nanoparticle (TiO2 or Ag) or AgNO3 (as a silver control) or were not exposed to an nanoparticles (control) to determine if the naoparticles affected PHB production.
Project description:Manufactured nanomaterials (MNMs) are increasingly incorporated into consumer products that are disposed into sewage. In wastewater treatment, MNMs adsorb to activated sludge biomass where they may impact biological wastewater treatment performance, including nutrient removal. Here, we studied MNM effects on bacterial polyhydroxyalkanoate (PHA), specifically polyhydroxybutyrate (PHB), biosynthesis because of its importance to enhanced biological phosphorus (P) removal (EBPR). Activated sludge was sampled from an anoxic selector of a municipal wastewater treatment plant (WWTP), and PHB-containing bacteria were concentrated by density gradient centrifugation. After starvation to decrease intracellular PHB stores, bacteria were nutritionally augmented to promote PHB biosynthesis while being exposed to either MNMs (TiO2 or Ag) or to Ag salts (each at a concentration of 5 mg L-1). Cellular PHB concentration and PhyloChip community composition were analyzed. The final bacterial community composition differed from activated sludge, demonstrating that laboratory enrichment was selective. Still, PHB was synthesized to near-activated sludge levels. Ag salts altered final bacterial communities, although MNMs did not. PHB biosynthesis was diminished with Ag (salt or MNMs), indicating the potential for Ag-MNMs to physiologically impact EBPR through the effects of dissolved Ag ions on PHB producers.
Project description:To further explore the biotoxicity mechanisms of TiO2 nanoparticles (NPs) and the recovery potentials of the impaired Nitrosomonas europaea (N. europaea, ATCC 19718) cells, a genome-sequenced model ammonia oxidizing bacterium (AOB) commonly detected in the activated sludge of biological wastewater treatment plants, the whole-genome microarray analysis was applied to retrieve the induced transcriptional responses during the long-term exposure, after the toxicity effects and the recovery potentials were assessed at both physiological and metabolic levels.
Project description:This project aimed to assess the toxicity underlying the exposure of Turbot (Scophthalmus maximus), an economically valuable fish species, to TiO2 and Ag nanoparticles (NPs). To carry out the study, juvenile fish were exposed to TiO2 and Ag NPs incorporated in the diet. After 14 days of exposure fish were euthanized and liver and kidney samples collected for proteomics. The shotgun proteomics analysis revealed quantitative changes in multiple proteins. The results suggest effects of TiO2 and Ag NPs in energy/lipid metabolism and for instance alterations in ribosome functions, protein biosynthesis and related processes. This proteomic study provided as well candidate biomarkers for NPs exposure in aquaculture species.
Project description:To further explore and differentiate the biotoxicity mechanisms of individual nanoparticles (NPs) and NP mixture on Nitrosomonas europaea (N. europaea, ATCC 19718) at genetic level, a genome-sequenced model ammonia oxidizing bacterium (AOB) commonly detected in the activated sludge of biological wastewater treatment plants, the induced whole-genome expressions were analyzed with the high throughput Microarray technique, after the dose-dependent changes of N. europaea’s physiological, metabolic and AMO enzyme activities in single and dual component NP systems was evaluated. NP stress induced gene expressions were measured after 6hr exposure to 10 ppm nano-ZnO, 50 nano-TiO2 and their mixture.Three independent experiments were performed for each experiment.
Project description:Infections associated with antimicrobial-resistant bacteria now represent a significant threat to human health using conventional therapy, necessitating the development of alternate and more effective antibacterial compounds. Silver nanoparticles (Ag NPs) have been proposed as potential antimicrobial agents to combat infections. A complete understanding of their antimicrobial activity is required before these molecules can be used in therapy. Lysozyme coated Ag NPs were synthesized and characterized by TEMEDS, XRD, UV-vis, FTIR spectroscopy, zeta potential, and oxidative potential assay. Biochemical assays and deep level transcriptional analysis using RNA sequencing were used to decipher how Ag NPs exert their antibacterial action against multi-drug resistant Klebsiella pneumoniae MGH78578. RNAseq data revealed that Ag NPs induced a triclosan-like bactericidal mechanism responsible for the inhibition of the type II fatty acid biosynthesis. Additionally, released AgC generated oxidative stress both extra and intracellularly in K. pneumoniae. The data showed that triclosan-like activity and oxidative stress cumulatively underpinned the antibacterial activity of Ag NPs. This result was confirmed by the analysis of the bactericidal effect of Ag NPs against the isogenic K. pneumoniae MGH78578 1soxS mutant, which exhibits a compromised oxidative stress response compared to the wild type. Silver nanoparticles induce a triclosan like antibacterial action mechanism in multi-drug resistant K. pneumoniae. This study extends our understanding of anti-Klebsiella mechanisms associated with exposure to Ag NPs. This allowed us to model how bacteria might develop resistance against silver nanoparticles, should the latter be used in therapy.
Project description:The nematode C. elegans was exposed to TiO2 nanoparticles (NPs) to evaluate the ecotoxicity of TiO2 nanoparticles. We used the DNA microarray method to understand changes in gene expression after the exposure to TIO2 NPs. We identified various genes involved in metal detoxification as well as in regulating worm development.
Project description:Little progress has been made in studying the toxicity of realistic 'non-pristine' forms of nanoparticles that presents in real soil environment. It is presently unkown whether the transformed nanoparticles in realistic environment exerts an adverse effect to rhizobium-legume symbiosis on molecular level. We used microarray to investigate the toxicogenomic responses of the model legume Medicago truncatula following 30 days exposure to three different types of biosolids (control biosolids (control BS), a mixture of Ag, ZnO and TiO2 manufactured nanomaterials added biosolids (Nano BS) and a corresponding bulk metals added biosolids (Bulk BS) ) amended soil that were aged for 6 months prior to exposure in pot experiment.
Project description:In the present study, we investigated the transcriptional expression patterns of the model strain E. coli exposed to titanium dioxide nanoparticles (NP-TiO2), under dark conditions by using a microarray. Expression profiles were compared to unexposed E.coli and ratio of expression were analysed. Cell exposure to NP-TiO2 was conducted in 10 mM NaCl, E. coli bacterial suspension and NP-TiO2 stock suspension (or mQ water for the control) were added to the NaCl solution to obtain final concentrations of 10E7 cells/ml and 100 mg/l of TiO2 nanoparticles. The flasks were then incubated at 20M-BM-0C on a dark rotary shaker for 5 h. Exposed NP-TiO2: 4 biological replicats. Control: 4 biological replicats.