Characterization of Wastewater Treatment Plant Microbial Communities and the Effects of Carbon Sources on Diversity in Laboratory Models

Abstract

We are developing a laboratory-scale model to improve our understanding and capacity to assess the biological risks of genetically engineered bacteria and their genetic elements in the natural environment. Our hypothetical scenario concerns an industrial bioreactor failure resulting in the introduction of genetically engineered bacteria to a downstream municipal wastewater treatment plant (MWWTP). As the first step towards developing a model for this scenario, we sampled microbial communities from the aeration basin of a MWWTP at three seasonal time points. Having established a baseline for community composition, we investigated how the community changed when propagated in the laboratory, including cell culture media conditions that could provide selective pressure in future studies. Specifically, using PhyloChip 16S-rRNA-gene targeting microarrays, we compared the compositions of sampled communities to those of inocula propagated in the laboratory in simulated wastewater conditionally amended with various carbon sources (glucose, chloroacetate, D-threonine) or the ionic liquid 1-ethyl-3-methylimidazolium chloride ([C2mim]Cl). Proteobacteria, Bacteroidetes, and Actinobacteria were predominant in both aeration basin and laboratory-cultured communities. Laboratory-cultured communities were enriched in γ-Proteobacteria. Enterobacteriaceae, and Aeromonadaceae were enriched by glucose, Pseudomonadaceae by chloroacetate and D-threonine, and Burkholderiacea by high (50 mM) concentrations of chloroacetate. Microbial communities cultured with chloroacetate and D-threonine were more similar to sampled field communities than those cultured with glucose or [C2mim]Cl. Although observed relative richness in operational taxonomic units (OTUs) was lower for laboratory cultures than for field communities, both flask and reactor systems supported phylogenetically diverse communities. These results importantly provide a foundation for laboratory models of industrial bioreactor failure scenarios.

Comparative diversity of microbiomes and Resistomes in beef feedlots, downstream environments and urban sewage influent

“…Proteobacteria (83.5%), Bacteroidetes (10.4%) and Firmicutes (3.8%) represented the majority of sewage microbes with Acinetobacter (29%) and Aeromonas (16%) being the most abundant of the Proteobacteria. Others have found Proteobacteria to be among the most abundant bacteria in urban wastewater followed by Bacteroidetes and Firmicutes [34]. Acinetobacter johnsii and Acinetobacter baumannii accounted for the majority of the Acinetobacter identified.…”

Effect of hydraulic retention time on microbial community structure in wastewater treatment electro‐bioreactors

“…Additionally, Enterobacteriaceae , Verrucomicrobiaceae , Neisseriaceae , Pseudomonadaceae and Sphingomonadaceae were present in electro‐bioreactors operated at HRT of 6 hr with higher relative abundance (26.1, 2.1, 1.1, 0.9 and 0.5%, respectively) than in the control bioreactors (13.8, 1.3, 0.8, 0.4 and 0.2%, respectively). Therefore, these bacterial families favored electro‐bioreactors subjected to an electric current density of 3 Am −2 operated at HRT of 6 hr were affiliated with better biological nutrient removal (Cydzik‐Kwiatkowska & Zielińska, ; Lee et al., ; Nielsen et al., ; Valentín‐Vargas, Toro‐Labrador, & Massol‐Deyá, ) (Figure a, b, c and d).…”

“…Pseudomonas and Flavobacterium have been previously reported that they can remove sCOD (Abdel‐Raouf, Al‐Homaidan, & Ibraheem, ; Nasr, ). Additionally, there was an observed high removal of sCOD in electro‐bioreactors operated at HRT of 6 hr which could be due to the electric current impact resulting in stimulating the growth of bacterial communities associated with sCOD reduction such as Lactococcus, Pseudomonas and Flavobacterium (Lee et al., ; Nielsen, Nguyen, Meyer, & Nielsen, ; Park et al., ). Our results showed that there was a higher relative abundance of those genera in electro‐bioreactors operated at HRT of 6 hr (5.8, 4.3 and 3.7%, respectively) than in control bioreactors (0.1, 1.1, and 2.1%, respectively).…”

Metagenomic analysis of an ecological wastewater treatment plant’s microbial communities and their potential to metabolize pharmaceuticals

“…However, metagenomic analyses of the microbial ecology of conventional (activated sludge) wastewater systems have been described elsewhere 59– 62 .…”

“…There is limited ability to relate the results of our analysis of the microbial communities of this ecological WWTP to that of other systems serving different populations and geographic locations as this appears to be the first published findings on the topic. However, metagenomic analyses of the microbial ecology of conventional (activated sludge) wastewater systems have been described elsewhere 59 – 62 .…”