Project description:In response to the issues of low denitrification efficiency and high N₂O emissions in the biological nitrogen removal process of low C/N municipal wastewater, studies typically address these challenges by adding carbon sources. In this study, the addition of microorganisms enhanced the carbon flow and electron transport for nitrate reduction, significantly improving the denitrification performance of low C/N wastewater and reducing N₂O production. Proteomic analysis was employed to explore the mechanisms underlying this effect. The results revealed that the metabolites produced by the added microorganisms, S. oneidensis MR-1 and B. subtilis, including biosurfactants, heme, and cytochromes, altered the intracellular carbon redistribution in P. denitrificans, leading to an increased carbon flow directed towards nitrate reduction, thus enhancing total nitrogen removal efficiency.
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:Municipal wastewater effluent can impact its receiving environment. In the St. Lawrence River, male fish living downstream from Montreal exhibit increased hepatic vitellogenin, intersex, delayed spermatogenesis and altered immune function. Few studies have examined genome-wide effects associated with municipal effluent exposure in fish to decipher the mechanisms of toxicity. The present objective was to identify hepatic cellular signaling pathways in fathead minnows following exposure to municipal wastewater effluent. Immature minnows were exposed for 21 days to either 0% (Control) or 20% municipal effluent, the highest concentration in the St. Lawrence River. Hepatic RNA was extracted and used to hybridize a fathead minnow oligonucleotide microarray containing approximately 15K gene sequences.
2014-08-31 | GSE52693 | GEO
Project description:Nitrogen removal from domestic wastewater by biological methods
Project description:Microarray analysis of Aspergillus niger under conditions with differing combinations of carbon source, nitrogen source, nitrogen concentration, and culture pH Fermentor cultures were grown in minimal medium (MM) at a constant temperature of 30 ± 0.5 ºC and with differing combinations of carbon source (either 277.5 mM glucose or 333.0 mM xylose), nitrogen source (NH4Cl or NaNO3) and nitrogen concentration (4x: 282.4 mM; 8x: 564.8 mM), and pH (pH4 or pH5) of the medium (M. Braaksma, A.K. Smilde, M.J. van der Werf, P.J. Punt, submitted for publication). At different time points samples were collected, quenched immediately in methanol at -45 ºC and centrifuged at -20 ºC to remove supernatant. Part of the biomass was frozen into liquid nitrogen and stored at -80 ºC for microarray analysis. For each of the 16 culture conditions one sample was selected for microarray analysis; samples were collected either around the time point carbon source depleted or a considerable time (~24 h) after carbon souce depletion. In addition some technical duplicates were included.
Project description:Anaerobic ammonium oxidizing (anammox) bacteria mediate a key step in the biogeochemical nitrogen cycle and have been applied worldwide for the energy-efficient removal of nitrogen from wastewater. However, outside their core energy metabolism, little is known about the metabolic networks driving anammox bacterial anabolism and mixotrophy beyond genome predictions. Here, we experimentally resolved the central carbon metabolism using metabolomics (LC-MS and GC-MS), metabolic flux analysis and proteomics (shot-gun proteomics).
Project description:Biological treatments to degrade cyanide are a powerful technology for cyanide removal from industrial wastewaters. It has been previously demonstrated that the alkaliphilic bacterium Pseudomonas pseudoalcaligenes CECT5344 is able to use free cyanide and several metal-cyanide complexes as the sole nitrogen source. In this work, the strain CECT5344 has been used for detoxification of the different chemical forms of cyanide that are present in alkaline wastewaters from the jewelry industry. This liquid residue also contains large concentrations of metals like iron, copper and zinc, making this wastewater even more toxic. To elucidate the molecular mechanisms involved in the bioremediation process, a quantitative sRNA sequencing analysis has been carried out in P. pseudoalcaligenes CECT5344 cells grown with the jewelry residue, free cyanide and ammonium as sole nitrogen sources.
Project description:Municipal wastewater effluent can impact its receiving environment. In the St. Lawrence River, male fish living downstream from Montreal exhibit increased hepatic vitellogenin, intersex, delayed spermatogenesis and altered immune function. Few studies have examined genome-wide effects associated with municipal effluent exposure in fish to decipher the mechanisms of toxicity. The present objective was to identify hepatic cellular signaling pathways in fathead minnows following exposure to municipal wastewater effluent. Immature minnows were exposed for 21 days to either 0% (Control) or 20% municipal effluent, the highest concentration in the St. Lawrence River. Hepatic RNA was extracted and used to hybridize a fathead minnow oligonucleotide microarray containing approximately 15K gene sequences. Sixteen samples were examined, 8 control samples and 8 exposed samples.