Project description:Landfill leachate water is often treated in a biological processing step. In most cases a stable operation of the industrial scale plants is controlled by sum parameters such as process relevant ion concentrations, dry matter concentration and dissolved oxygen concentration. A deeper understanding of the current status of the individual cell or the biocoenosis would help to understand malfunctions or the reason for inefficient plant performance. In a simple batch experimental setup, samples of two different conditions have been generated to unravel bacterial proteome changes in response to medium term lack of oxygen supply and landfill leachate addition. The first condition was an activated sludge sample condition from an industrial scale landfill leachate treatment plant with the process stages of nitrification and denitrification. After 45 days without aeration and with addition of leachate and carbon sources as fed batch, the second sample (condition 2) was taken. A comprehensive LC-MS/MS based protemic screen was performed aiming for the identification and quantification of waste water specific bacteria proteomes. To this end, a novel combination of two protein extraction methods has been established meeting the requirements for LC-MS/MS anaylsis. Around 600 proteins were identified of which 90 % were quantified in at least 3 replicates. Numerous essential proteins to maintain the cell redox homeostasis are overexpressed in the condition 1 which was aerated with oxygen and stressed by the ultrafiltration compared to condition 2, which was not aerated in a lab experiment. In addition, heat and cold shock proteins and two proteins related to the apoptosis of organisms (spermidine/putrescine transport system and apoptosis-inducing factor) were identified.
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: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:Here we report a metatranscriptomic analysis of gene expression and regulation of “Candidatus Accumulibacter”-enriched lab-scale sludge during enhanced biological phosphorus removal (EBPR). Medium density oligonucleotide microarrays were generated with probes targeting most predicted genes hypothesized to be important for the EBPR phenotype. The objectives were to investigate which genes were expressed during EBPR and which genes were differentially expressed between the early stage of anaerobic and aerobic phases (defined as 15 min after acetate addition and 15 min after switching to aeration respectively).
Project description:The performance of a lab-scale wastewater treatment plant during the start-up phase was investigated. A period of varying pH resulted in the loss of ammonium removal efficiency together with a decrease in the specific autotrophic oxygen uptake rate (OUR). From the OUR, it was inferred that the ammonium oxidizing bacteria (AOB) were inhibited by the fluctuation in the pH values. However, OUR alone could not provide the information as to how the AOB were affected at the molecular level. To gain a better insight, shotgun proteomic method was used in this work to quantify the total proteins in the system. Label-free quantification (LFQ) showed that during the time of poor ammonium removal, the marker enzyme hydroxylamine oxidase found in Nitrosomonas sp. was at the lowest LFQ intensity. Based on these results, proteomics has the potential to be used as a monitoring tool. Nevertheless, there are still some restrictions when measuring activated sludge using proteomic method such as the availability of a suitable proteomic database. In this paper, we describe our experience of using publicly available database for identification of activated sludge proteins.