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:Wastewater treatment plants use a variety of bioreactor types and configurations to remove organic matter and nutrients. Little is known regarding the effects of different configurations and within-plant immigration on microbial community dynamics. Previously, we found that the structure of ammonia-oxidizing bacterial (AOB) communities in a full-scale dispersed growth activated sludge bioreactor correlated strongly with levels of NO2- entering the reactor from an upstream trickling filter (Wells et al 2009). Here, to further examine this puzzling association, we profile within-plant microbial biogeography (spatial variation) and test the hypothesis that substantial microbial immigration occurs along a transect (raw influent, trickling filter biofilm, trickling filter effluent, and activated sludge) at the same full-scale wastewater treatment plant. AOB amoA gene abundance increased >30-fold between influent and trickling filter effluent concomitant with NO2- production, indicating unexpected growth and activity of AOB within the trickling filter. Nitrosomonas europaea was the dominant AOB phylotype in trickling filter biofilm and effluent, while a distinct ‘Nitrosomonas-like’ lineage dominated in activated sludge. Prior time series indicated that this ‘Nitrosomonas-like’ lineage was dominant when NO2- levels in the trickling filter effluent (i.e., activated sludge influent) were low, while N. europaea became dominant in the activated sludge when NO2- levels were high. This is consistent with the hypothesis that NO2- production may co-occur with biofilm sloughing, releasing N. europaea from the trickling filter into the activated sludge bioreactor. Phylogenetic microarray (PhyloChip) analyses revealed significant spatial variation in taxonomic diversity, including a large excess of methanogens in the trickling filter relative to activated sludge and attenuation of Enterobacteriaceae across the transect, and demonstrated transport of a highly diverse microbial community via the trickling filter effluent to the activated sludge bioreactor. Our results provide compelling evidence that substantial immigration between coupled process units occurs and may exert significant influence over microbial community dynamics within staged bioreactors.
Project description:In this study, two multiantibiotic-resistant bacteria, Ochrobactrum intermedium (N1) and Stenotrophomonas acidaminiphila (N2), were isolated from the sludge of a PWWTP in Guangzhou, China. Whole-genome sequencing revealed that N1 and N2 had genome sizes of 0.52 Mb and 0.37 Mb, respectively, and harbored 33 and 24 ARGs, respectively. The main resistance mechanism in the identified ARGs included efflux pumps, enzymatic degradation, and target bypass, with the N1 strain possessing more multidrug-resistant efflux pumps than the N2 strain (22 vs 12). This also accounts for the broader resistance spectrum of N1 than of N2 in antimicrobial susceptibility tests. Additionally, both genomes contain numerous mobile genetic elements (89 and 21 genes, respectively) and virulence factors (276 and 250 factors, respectively), suggesting their potential for horizontal transfer and pathogenicity.
Project description:The aim of the study is to identify and verify one or more gut bacteria of which the abundance in feces may help to early diagnosis colorectal cancer.
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.
Project description:Incomplete antibiotic removal in pharmaceutical wastewater treatment plants (PWWTPs) could lead to the development and spread of antibiotic-resistant bacteria (ARBs) and genes (ARGs) in the environment, posing a growing public health threat. In this study, two multiantibiotic-resistant bacteria, Ochrobactrum intermedium (N1) and Stenotrophomonas acidaminiphila (N2), were isolated from the sludge of a PWWTP in Guangzhou, China. The N1 strain was highly resistant to ampicillin, cefazolin, chloramphenicol, tetracycline, and norfloxacin, while the N2 strain exhibited high resistance to ampicillin, chloramphenicol, and cefazolin. Whole-genome sequencing revealed that N1 and N2 had genome sizes of 0.52 Mb and 0.37 Mb, respectively, and harbored 33 and 24 ARGs, respectively. The main resistance mechanism in the identified ARGs included efflux pumps, enzymatic degradation, and target bypass, with the N1 strain possessing more multidrug-resistant efflux pumps than the N2 strain (22 vs 12). This also accounts for the broader resistance spectrum of N1 than of N2 in antimicrobial susceptibility tests. Additionally, both genomes contain numerous mobile genetic elements (89 and 21 genes, respectively) and virulence factors (276 and 250 factors, respectively), suggesting their potential for horizontal transfer and pathogenicity. Overall, this research provides insights into the potential risks posed by ARBs in pharmaceutical wastewater and emphasizes the need for further studies on their impact and mitigation strategies.