Heidi Gough - Academia.edu (original) (raw)

Papers by Heidi Gough

Resources, Environment and Sustainability

Biotechnology for Biofuels

Background: Production and use of bio-based products offer advantages over conventional petrochem... more Background: Production and use of bio-based products offer advantages over conventional petrochemicals, yet the relatively high cost of production has restricted their mainstream adoption. Optimization of wastewater treatment processes could reduce capital expenditures, lowering the barrier to market entry for lignocellulosic biorefineries. This paper characterizes wastewater associated with lignocellulosic ethanol production and evaluates potential wastewater treatment operations. Results: It is found that organic material is intrinsic to bioconversion wastewater, representing up to 260 kg of biological oxygen demand per tonne of feedstock processed. Inorganics in the wastewater largely originate from additions during pretreatment and pH adjustments, which increase the inorganic loading by 44 kg per tonne of feedstock processed. Adjusting the ethanol production process to decrease addition of inorganic material could reduce the demands and therefore cost of waste treatment. Various waste treatment technologies-including those that take advantage of ecosystem services provided by feedstock production-were compared in terms of capital and operating costs, as well as technical feasibility. Conclusions: It is concluded that wastewater treatment technologies should be better integrated with conversion process design and feedstock production. Efforts to recycle resources throughout the biofuel supply chain through application of ecosystem services provided by adjacent feedstock plantations and recovery of resources from the waste stream to reduce overall capital and operating costs of bioconversion facilities.

Environmental Science & Technology, 2015

Gemfibrozil is a widely used hypolipidemic and triglyceride lowering drug. Excess of the drug is ... more Gemfibrozil is a widely used hypolipidemic and triglyceride lowering drug. Excess of the drug is excreted and discharged into the environment primarily via wastewater treatment plant effluents. Bacillus sp. GeD10, a gemfibrozil-degrader, was previously isolated from activated sludge. It is the first identified bacterium capable of degrading gemfibrozil. Gemfibrozil degradation by Bacillus sp. GeD10 was here studied through genome sequencing, quantitative proteomics and metabolite analysis. From the bacterial proteome of Bacillus sp. GeD10 1974 proteins were quantified, of which 284 proteins were found to be overabundant by more than 2-fold (FDR corrected p-value ≤0.032, fold change (log2) ≥ 1) in response to gemfibrozil exposure. Metabolomic analysis identified two hydroxylated intermediates as well as a glucuronidated hydroxyl-metabolite of gemfibrozil. Overall, gemfibrozil exposure in Bacillus sp. GeD10 increased the abundance of several enzymes potentially involved in gemfibrozil degradation as well as resulted in the production of several gemfibrozil metabolites. The potential catabolic pathway/modification included ring-hydroxylation preparing the substrate for subsequent ring cleavage by a meta-cleaving enzyme. The identified genes may allow for monitoring of potential gemfibrozil-degrading organisms in situ and increase the understanding of microbial processing of trace level contaminants. This study represents the first omics study on a gemfibrozil-degrading bacterium.

Proceedings of the Water Environment Federation, 2014

Environmental science & technology, Jan 21, 2015

Discharge of the endocrine disrupting compound bisphenol A (BPA) with wastewater treatment plant ... more Discharge of the endocrine disrupting compound bisphenol A (BPA) with wastewater treatment plant (WWTP) effluents into surface waters result in deleterious effects on aquatic life. Sphingobium sp. BiD32 was previously isolated from activated sludge based on its ability to degrade BPA. This study investigated BPA metabolism by Sphingobium sp. BiD32 using label-free quantitative proteomics. The genome of Sphingobium sp. BiD32 was sequenced to provide a species-specific platform for optimal protein identification. The bacterial proteomes of Sphingobium sp. BiD32 in the presence and absence of BPA were identified and quantified. A total of 2155 proteins were identified, 1174 of these proteins were quantified, and 184 of these proteins had a statistically significant change in abundance in response to the presence/absence of BPA (p ≤ 0.05). Proteins encoded for by genes previously identified to be responsible for protocatechuate degradation were upregulated in the presence of BPA. The analys...

Environmental Engineering Science, 2015

ABSTRACT Biodegradation is the primary removal mechanism of the potent endocrine-disrupting estro... more ABSTRACT Biodegradation is the primary removal mechanism of the potent endocrine-disrupting estrogen 17α-ethinylestradiol (EE2) during activated sludge (AS) wastewater treatment. Analysis of AS treatment process designs to optimize EE2 removal requires knowledge of EE2 biodegradation kinetics. However, there is little information on EE2 biodegradation kinetics for different types of systems and under long-term studies. EE2 biodegradation kinetics were investigated at 20°C using laboratory-scale sequencing batch reactors simulating aerobic, anaerobic/aerobic enhanced biological phosphorus removal, and anoxic/aerobic biological nitrogen removal processes fed synthetic wastewater. Three sets of reactor experiments were conducted using different municipal AS plant seed sources and with solid retention times (SRTs) ranging from 8 to 13 days. EE2 biodegradation was described by a pseudo first-order biodegradation rate model with a rate coefficient (kb) normalized to the reactor volatile suspended solids (VSS). EE2 kb values were determined from batch degradation tests and from calibration of the model to the reactor process. Significant EE2 biodegradation occurred only under aerobic conditions. Observed EE2 kb values for aerobic, anaerobic/aerobic, and anoxic/aerobic operations ranged from 4 to 22 L/g VSS-day, 4 to 19 L/g VSS-day, and 3 to 20 L/g VSS-day, respectively. Model simulations showed that the EE2 removal efficiency could range from 72% to over 99% for these coefficients at a 10-day SRT. Predicted EE2 removal efficiency at a given kb value can be improved by operating at a higher SRT upto a limit, by having a greater number of aerobic reactor stages, and by having a higher influent biodegradable chemical oxygen demand concentration.

FEMS microbiology ecology, 2015

The ecophysiology of long-chain fatty acid-degrading syntrophic β-oxidizing bacteria has been poo... more The ecophysiology of long-chain fatty acid-degrading syntrophic β-oxidizing bacteria has been poorly understood due to a lack of quantitative abundance data. Here, TaqMan quantitative PCR (qPCR) assays targeting the 16S rRNA gene of the known mesophilic syntrophic β-oxidizing bacterial genera Syntrophomonas and Syntrophus were developed and validated. Microbial community dynamics were followed using qPCR and Illumina-based high-throughput amplicon sequencing in triplicate methanogenic bioreactors subjected to five consecutive batch feedings of oleic acid. With repeated oleic acid feeding, the initial specific methane production rate significantly increased along with the relative abundances of Syntrophomonas and methanogenic archaea in the bioreactor communities. The novel qPCR assays showed that Syntrophomonas increased from 7 to 31% of the bacterial community 16S rRNA gene concentration, whereas that of Syntrophus decreased from 0.02 to less than 0.005%. High-throughput amplicon s...

Proceedings of the Water Environment Federation, 2008

Abstract: Biodiesel fuel is an attractive renewable energy alternative that generates glycerol-ri... more Abstract: Biodiesel fuel is an attractive renewable energy alternative that generates glycerol-rich byproducts. Stable anaerobic sludge digestion with continuously-or intermittently-fed biodiesel waste was demonstrated. Two parallel completely-mixed laboratory-scale ...

Proceedings of the Water Environment Federation, 2009

... Christopher D. Muller 1* , Heidi Louis Gough 2 , Diane Nelson 2 , John Ferguson 2 , H. David ... more ... Christopher D. Muller 1* , Heidi Louis Gough 2 , Diane Nelson 2 , John Ferguson 2 , H. David Stensel 2 , Pamela Randolph 3 ... Figure 6: The change in methane generation due to co-digestion of Substrate H with sewage sludge: Gas volumes are reported at STP. ...

Bioresource Technology, 2014

Pharmaceutical and personal care products (PPCPs) discharged with wastewater treatment effluents ... more Pharmaceutical and personal care products (PPCPs) discharged with wastewater treatment effluents are a surface water quality concern. PPCPs are partially removed during wastewater treatment and biological transformation is an important removal mechanism. To investigate the potential for enhanced PPCP removal using bioaugmentation, bacteria were previously isolated from activated sludge capable of degrading PPCPs to ng/L concentrations. This study examined the degradation kinetics of triclosan and bisphenol A by five of these bacteria, both in pure culture and when augmented to activated sludge. Sorption coefficients were determined to account for the influence of partitioning during bioremoval. When the bacteria were added to activated sludge, degradation increased. Experimentally determined kinetic parameters were used to model a full-scale continuous treatment process, showing that low biomass could achieve reduced effluent PPCP concentrations. These results demonstrated that bioaugmentation may improve PPCP removal using established wastewater infrastructure under conditions of high solids partitioning.

Water Environment Research, 2013

Recent interest in carbon-neutral biofuels has revived interest in co-digestion for methane gener... more Recent interest in carbon-neutral biofuels has revived interest in co-digestion for methane generation. At wastewater treatment facilities, organic wastes may be co-digested with sludge using established anaerobic digesters. However, changes to organic loadings may induce digester instability, particularly for thermophilic digesters. To examine this problem, thermophilic (55 degrees C) co-digestion was studied for two food-industry wastes in semi-continuous laboratory digesters; in addition, the wastes' biochemical methane potentials were tested. Wastes with high chemical oxygen demand (COD) content were selected as feedstocks allowing increased input of potential energy to reactors without substantially altering volumetric loadings. Methane generation increased while reactor pH and volatile solids remained stable. Lag periods observed prior to methane stimulation suggested that acclimation of the microbial community may be critical to performance during co-digestion. Chemical oxygen demand mass balances in the experimental and control reactors indicated that all of the food industry waste COD was converted to methane.

The ISME Journal, 2011

Contamination, such as by heavy metals, has frequently been implicated in altering microbial comm... more Contamination, such as by heavy metals, has frequently been implicated in altering microbial community structure. However, this association has not been extensively studied for anaerobic communities, or in freshwater lake sediments. We investigated microbial community structure in the metal-contaminated anoxic sediments of a eutrophic lake that were impacted over the course of 80 years by nearby zinc-smelting activities. Microbial community structure was inferred for bacterial, archaeal and eukaryotic populations by evaluating terminal restriction fragment length polymorphism (TRFLP) patterns in near-surface sediments collected in triplicate from five areas of the lake that had differing levels of metal contamination. The majority of the fragments in the bacterial and eukaryotic profiles showed no evidence of variation in association with metal contamination levels, and diversity revealed by these profiles remained consistent even as metal concentrations varied from 3000 to 27 000 mg kg À1 total Zn, 0.125 to 11.2 lM pore water Zn and 0.023 to 5.40 lM pore water As. Although most archaeal fragments also showed no evidence of variation, the prevalence of a fragment associated with mesophilic Crenarchaeota showed significant positive correlation with total Zn concentrations. This Crenarchaeota fragment dominated the archaeal TRFLP profiles, representing between 35% and 79% of the total measured peak areas. Lake DePue 16S rRNA gene sequences corresponding to this TRFLP fragment clustered with anaerobic and soil mesophilic Crenarchaeota sequences. Although Crenarchaeota have been associated with metal-contaminated groundwater and soils, this is a first report (to our knowledge) documenting potential increased prevalence of Crenarchaeota associated with elevated levels of metal contamination.

PLoS ONE, 2013

The objective of this study was to characterize the morphology, size-distribution, concentration ... more The objective of this study was to characterize the morphology, size-distribution, concentration and genome size of virus-like particles (VLPs) in two acetate-fed Methanosaeta-dominated reactors to better understand the possible correlation between viruses and archaeal hosts. The study reactors were dominated by a single genus of acetoclastic methanogen, Methanosaeta, which was present at 6 to 13 times higher than the combined bacterial populations consisting of Proteobacteria, Firmicutes, and Bacteroidetes. Epifluorescent microscopy showed VLPs concentration of 7.1 ± 1.5×10 7 VLPs/ml and 8.4 ± 4.3×10 7 VLPs/ml in the two laboratory reactors. Observations of no detectable import of VLPs with the reactor feed combined long operational time since the last inocula were introduced suggests that the VLP populations were actively propagating in the reactors. Transmission electron microscopy images showed VLPs with morphology consistent with Siphoviridae in both reactors, and VLPs with morphologies consistent with Myoviridae in one of the reactors. The morphology, size-distribution and genome size of VLPs were distinct between reactors suggesting that unique viral populations inhabited each reactor, though the hosts of these VLPs remain unclear.

Journal of Microbiological Methods, 2003

This study reports a method for optimizing direct counts of bacteria in sediment, designed to red... more This study reports a method for optimizing direct counts of bacteria in sediment, designed to reduce the masking by sediment particles. The protocol was designed to determine appropriate dilution factors by incorporating counting statistics and was used to measure depth-associated changes in microbial abundance in metal-impacted freshwater sediments. We demonstrated a direct method to determine appropriate sample dilution for accurate counting by adding a known amount of cells to the sediment. For accurate counting in our sediment samples, we determined that the average number of bacteria per microscope ocular field must be between 8.5 and 10. This is well below the 30 bacteria/field previously suggested for accurate counting. These results indicate that an optimal dilution rate must be determined before accurate direct counts in sediment can be achieved.

Journal of Geophysical Research, 2008

1] Although sulfate-reducing prokaryotes have long been studied as agents of metals bioremediatio... more 1] Although sulfate-reducing prokaryotes have long been studied as agents of metals bioremediation, impacts of long-term metals exposure on biologically mediated sulfur cycling in natural systems remains poorly understood. The effects of long-term exposure to metal stress on the freshwater sulfur cycle were studied, with a focus on biologic sulfate reduction using a combination of microbial and chemical methods. To examine the effects after decades of adaptation time, a field-based experiment was conducted using multiple study sites in a natural system historically impacted by a nearby zinc smelter (Lake DePue, Illinois). Rates were highest at the most metals-contaminated sites ($35 mmol/cm 3 /day) and decreased with decreased pore water zinc and arsenic contamination levels, while other environmental characteristics (i.e., pH, nutrient concentrations and physical properties) showed little between-site variation. Correlations were established using an artificial neural network to evaluate potentially non-linear relationships between sulfate reduction rates (SRR) and measured environmental variables. SRR in Lake DePue were up to 50 times higher than rates previously reported for lake sediments and the chemical speciation of Zn was dominated by the presence of ZnS as shown by X-ray Absorption Spectroscopy (XAS). These results suggest that long-term metal stress of natural systems might alter the biogeochemical cycling of sulfur by contributing to higher rates of sulfate reduction. (2008), Elevated sulfate reduction in metal-contaminated freshwater lake sediments,

Journal of Geophysical Research, 2008

Little is known about the long-term impacts of metal contamination on the microbiota of anoxic la... more Little is known about the long-term impacts of metal contamination on the microbiota of anoxic lake sediments. In this study, we examined microbial biomass and metals (arsenic, cadmium, chromium, copper, iron, lead, manganese, and zinc) in the sediments of Lake DePue, a backwater lake located near a former zinc smelter. Sediment core samples were examined using two independent measures for microbial biomass (total microscopic counts and total phospholipidphosphate concentrations), and for various fractions of each metal (pore water extracts, sequential extractions, and total extracts of all studied metals and zinc speciation by X-ray absorption fine structure (XAFS). Zinc concentrations were up to 1000 times higher than reported for sediments in the adjacent Illinois River, and ranged from 21,400 mg/kg near the source to 1,680 mg/kg near the river. However, solid metal fractions were not well correlated with pore water concentrations, and were not good predictors of biomass concentrations. Instead, biomass, which varied among sites by as much as two-times, was inversely correlated with concentrations of pore water zinc and arsenic as established by multiple linear regression. Monitoring of other parameters known to naturally influence biomass in sediments (e.g., organic carbon concentrations, nitrogen concentrations, pH, sediment texture, and macrophytes) revealed no differences that could explain observed biomass trends. This study provides strong support for control of microbial abundance by pore water metal concentrations in contaminated freshwater sediments.

Environmental Science & Technology, 2009

Six groundwater monitoring wells from the Field Research Center of the U.S. DOE Environmental Rem... more Six groundwater monitoring wells from the Field Research Center of the U.S. DOE Environmental Remediation Science Program (ERSP) at Oak Ridge, TN, were selected to compose a gradient of pH, nitrate and heavy metal contamination. DNA from the groundwater bacterial community was analyzed with a functional gene array containing 2,006 probes for the detection of genes involved in metal-resistance, sulfate-reduction, contaminant degradation and carbon and nitrogen cycling. Diversity decreased in relation to the level of contamination within each well, and each community exhibited a different distribution of genes. Heatmaps of metal resistance genes and nirK and nirS genes indicate that highly contaminated wells had lower gene diversity, but greater signal intensity for detected genes. Wells with the highest sulfate concentrations had the greatest diversity and signal intensity for dsrAB genes. A greater number of carbon fixation genes (cbbL, cbbM) were detected than fermentation genes (FTHFS) in all wells. A variety of organic contaminant degradation genes were also detected. Results of Mantel tests and canonical correspondence analysis indicate that nitrate, sulfate, pH, uranium and technetium have a significant (p < 0.05) effect on bacterial community structure. This study provides an overall picture of bacterial community structure in contaminated environments across many different functional genes and shows that diversity can vary widely in relation to the degree of contamination.

Biodegradation, 2013

Pharmaceutical and personal care products (PPCPs) discharged with wastewater treatment plant (WWT... more Pharmaceutical and personal care products (PPCPs) discharged with wastewater treatment plant (WWTP) effluents are an emerging surface water quality concern. Biological transformation has been identified as an important removal mechanism during wastewater treatment. The aim of this research was the identification of bacteria with characteristics for potential bioaugmentation to enhance PPCP removal. We report here the cultivation and characterization of bacteria capable of degrading PPCPs to ng/L concentrations. An isolation approach was developed using serial enrichment in mineral medium containing 1 mg/L of an individual PPCP as the sole organic carbon source available to heterotrophs until the original activated sludge inocula was diluted to ~10(-8) of its initial concentration, followed by colony growth on solid R2A agar. Eleven bacteria were isolated, eight that could remove triclosan, bisphenol A, ibuprofen, or 17β-estradiol to below 10 ng/L, one that could remove gemfibrozil to below 60 ng/L, and two that could remove triclosan or E2, but not to ng/L concentrations. Most bacterial isolates degraded contaminants during early growth when grown utilizing rich carbon sources and were only able to degrade the PPCPs on which they were isolated. Seven of the bacterial isolates were sphingomonads, including all the triclosan and bisphenol A degraders and the ibuprofen degrader. The study results indicate that the isolated bacteria may have a positive influence on removal in WWTPs if present at sufficient concentrations and may be useful for bioaugmentation.

Applied and Environmental Microbiology, 2003

Diversity, habitat range, and activities of sulfate-reducing prokaryotes within hot springs in Ye... more Diversity, habitat range, and activities of sulfate-reducing prokaryotes within hot springs in Yellowstone National Park were characterized using endogenous activity measurements, molecular characterization, and enrichment. Five major phylogenetic groups were identified using PCR amplification of the dissimilatory sulfite reductase genes (dsrAB) from springs demonstrating significant sulfate reduction rates, including a warm, acidic (pH 2.5) stream and several nearly neutral hot springs with temperatures reaching 89°C. Three of these sequence groups were unrelated to named lineages, suggesting that the diversity and habitat range of sulfate-reducing prokaryotes exceeds that now represented in culture.

Environmental Science & Technology, 2014

The removal of the potent endocrine-disrupting estrogen hormone, 17α-ethinylestradiol (EE2), in m... more The removal of the potent endocrine-disrupting estrogen hormone, 17α-ethinylestradiol (EE2), in municipal wastewater treatment plant (WWTP) activated sludge (AS) processes can occur through biodegradation by heterotrophic bacteria growing on other organic wastewater substrates. Different kinetic and metabolic substrate utilization conditions created with AS bioselector processes can affect the heterotrophic population composition in AS. The primary goal of this research was to determine if these changes also affect specific EE2 biodegradation kinetics. A series of experiments were conducted with parallel bench-scale AS reactors treating municipal wastewater with estrogens at 100-300 ng/L concentrations to evaluate the effect of bioselector designs on pseudo first-order EE2 biodegradation kinetics normalized to mixed liquor volatile suspended solids (VSS). Kinetic rate coefficient (kb) values for EE2 biodegradation ranged from 5.0 to 18.9 L/g VSS/d at temperatures of 18 °C to 24 °C. EE2 kb values for aerobic biomass growth at low initial food to mass ratio feeding conditions (F/Mf) were 1.4 to 2.2 times greater than that from growth at high initial F/Mf. Anoxic/aerobic and anaerobic/aerobic metabolic bioselector reactors achieving biological nutrient removal had similar EE2 kb values, which were lower than that in aerobic AS reactors with biomass growth at low initial F/Mf. These results provide evidence that population selection with growth at low organic substrate concentrations can lead to improved EE2 biodegradation kinetics in AS treatment.

Resources, Environment and Sustainability

Biotechnology for Biofuels

Background: Production and use of bio-based products offer advantages over conventional petrochem... more Background: Production and use of bio-based products offer advantages over conventional petrochemicals, yet the relatively high cost of production has restricted their mainstream adoption. Optimization of wastewater treatment processes could reduce capital expenditures, lowering the barrier to market entry for lignocellulosic biorefineries. This paper characterizes wastewater associated with lignocellulosic ethanol production and evaluates potential wastewater treatment operations. Results: It is found that organic material is intrinsic to bioconversion wastewater, representing up to 260 kg of biological oxygen demand per tonne of feedstock processed. Inorganics in the wastewater largely originate from additions during pretreatment and pH adjustments, which increase the inorganic loading by 44 kg per tonne of feedstock processed. Adjusting the ethanol production process to decrease addition of inorganic material could reduce the demands and therefore cost of waste treatment. Various waste treatment technologies-including those that take advantage of ecosystem services provided by feedstock production-were compared in terms of capital and operating costs, as well as technical feasibility. Conclusions: It is concluded that wastewater treatment technologies should be better integrated with conversion process design and feedstock production. Efforts to recycle resources throughout the biofuel supply chain through application of ecosystem services provided by adjacent feedstock plantations and recovery of resources from the waste stream to reduce overall capital and operating costs of bioconversion facilities.

Environmental Science & Technology, 2015

Gemfibrozil is a widely used hypolipidemic and triglyceride lowering drug. Excess of the drug is ... more Gemfibrozil is a widely used hypolipidemic and triglyceride lowering drug. Excess of the drug is excreted and discharged into the environment primarily via wastewater treatment plant effluents. Bacillus sp. GeD10, a gemfibrozil-degrader, was previously isolated from activated sludge. It is the first identified bacterium capable of degrading gemfibrozil. Gemfibrozil degradation by Bacillus sp. GeD10 was here studied through genome sequencing, quantitative proteomics and metabolite analysis. From the bacterial proteome of Bacillus sp. GeD10 1974 proteins were quantified, of which 284 proteins were found to be overabundant by more than 2-fold (FDR corrected p-value ≤0.032, fold change (log2) ≥ 1) in response to gemfibrozil exposure. Metabolomic analysis identified two hydroxylated intermediates as well as a glucuronidated hydroxyl-metabolite of gemfibrozil. Overall, gemfibrozil exposure in Bacillus sp. GeD10 increased the abundance of several enzymes potentially involved in gemfibrozil degradation as well as resulted in the production of several gemfibrozil metabolites. The potential catabolic pathway/modification included ring-hydroxylation preparing the substrate for subsequent ring cleavage by a meta-cleaving enzyme. The identified genes may allow for monitoring of potential gemfibrozil-degrading organisms in situ and increase the understanding of microbial processing of trace level contaminants. This study represents the first omics study on a gemfibrozil-degrading bacterium.

Proceedings of the Water Environment Federation, 2014

Environmental science & technology, Jan 21, 2015

Discharge of the endocrine disrupting compound bisphenol A (BPA) with wastewater treatment plant ... more Discharge of the endocrine disrupting compound bisphenol A (BPA) with wastewater treatment plant (WWTP) effluents into surface waters result in deleterious effects on aquatic life. Sphingobium sp. BiD32 was previously isolated from activated sludge based on its ability to degrade BPA. This study investigated BPA metabolism by Sphingobium sp. BiD32 using label-free quantitative proteomics. The genome of Sphingobium sp. BiD32 was sequenced to provide a species-specific platform for optimal protein identification. The bacterial proteomes of Sphingobium sp. BiD32 in the presence and absence of BPA were identified and quantified. A total of 2155 proteins were identified, 1174 of these proteins were quantified, and 184 of these proteins had a statistically significant change in abundance in response to the presence/absence of BPA (p ≤ 0.05). Proteins encoded for by genes previously identified to be responsible for protocatechuate degradation were upregulated in the presence of BPA. The analys...

Environmental Engineering Science, 2015

ABSTRACT Biodegradation is the primary removal mechanism of the potent endocrine-disrupting estro... more ABSTRACT Biodegradation is the primary removal mechanism of the potent endocrine-disrupting estrogen 17α-ethinylestradiol (EE2) during activated sludge (AS) wastewater treatment. Analysis of AS treatment process designs to optimize EE2 removal requires knowledge of EE2 biodegradation kinetics. However, there is little information on EE2 biodegradation kinetics for different types of systems and under long-term studies. EE2 biodegradation kinetics were investigated at 20°C using laboratory-scale sequencing batch reactors simulating aerobic, anaerobic/aerobic enhanced biological phosphorus removal, and anoxic/aerobic biological nitrogen removal processes fed synthetic wastewater. Three sets of reactor experiments were conducted using different municipal AS plant seed sources and with solid retention times (SRTs) ranging from 8 to 13 days. EE2 biodegradation was described by a pseudo first-order biodegradation rate model with a rate coefficient (kb) normalized to the reactor volatile suspended solids (VSS). EE2 kb values were determined from batch degradation tests and from calibration of the model to the reactor process. Significant EE2 biodegradation occurred only under aerobic conditions. Observed EE2 kb values for aerobic, anaerobic/aerobic, and anoxic/aerobic operations ranged from 4 to 22 L/g VSS-day, 4 to 19 L/g VSS-day, and 3 to 20 L/g VSS-day, respectively. Model simulations showed that the EE2 removal efficiency could range from 72% to over 99% for these coefficients at a 10-day SRT. Predicted EE2 removal efficiency at a given kb value can be improved by operating at a higher SRT upto a limit, by having a greater number of aerobic reactor stages, and by having a higher influent biodegradable chemical oxygen demand concentration.

FEMS microbiology ecology, 2015

The ecophysiology of long-chain fatty acid-degrading syntrophic β-oxidizing bacteria has been poo... more The ecophysiology of long-chain fatty acid-degrading syntrophic β-oxidizing bacteria has been poorly understood due to a lack of quantitative abundance data. Here, TaqMan quantitative PCR (qPCR) assays targeting the 16S rRNA gene of the known mesophilic syntrophic β-oxidizing bacterial genera Syntrophomonas and Syntrophus were developed and validated. Microbial community dynamics were followed using qPCR and Illumina-based high-throughput amplicon sequencing in triplicate methanogenic bioreactors subjected to five consecutive batch feedings of oleic acid. With repeated oleic acid feeding, the initial specific methane production rate significantly increased along with the relative abundances of Syntrophomonas and methanogenic archaea in the bioreactor communities. The novel qPCR assays showed that Syntrophomonas increased from 7 to 31% of the bacterial community 16S rRNA gene concentration, whereas that of Syntrophus decreased from 0.02 to less than 0.005%. High-throughput amplicon s...

Proceedings of the Water Environment Federation, 2008

Abstract: Biodiesel fuel is an attractive renewable energy alternative that generates glycerol-ri... more Abstract: Biodiesel fuel is an attractive renewable energy alternative that generates glycerol-rich byproducts. Stable anaerobic sludge digestion with continuously-or intermittently-fed biodiesel waste was demonstrated. Two parallel completely-mixed laboratory-scale ...

Proceedings of the Water Environment Federation, 2009

... Christopher D. Muller 1* , Heidi Louis Gough 2 , Diane Nelson 2 , John Ferguson 2 , H. David ... more ... Christopher D. Muller 1* , Heidi Louis Gough 2 , Diane Nelson 2 , John Ferguson 2 , H. David Stensel 2 , Pamela Randolph 3 ... Figure 6: The change in methane generation due to co-digestion of Substrate H with sewage sludge: Gas volumes are reported at STP. ...

Bioresource Technology, 2014

Pharmaceutical and personal care products (PPCPs) discharged with wastewater treatment effluents ... more Pharmaceutical and personal care products (PPCPs) discharged with wastewater treatment effluents are a surface water quality concern. PPCPs are partially removed during wastewater treatment and biological transformation is an important removal mechanism. To investigate the potential for enhanced PPCP removal using bioaugmentation, bacteria were previously isolated from activated sludge capable of degrading PPCPs to ng/L concentrations. This study examined the degradation kinetics of triclosan and bisphenol A by five of these bacteria, both in pure culture and when augmented to activated sludge. Sorption coefficients were determined to account for the influence of partitioning during bioremoval. When the bacteria were added to activated sludge, degradation increased. Experimentally determined kinetic parameters were used to model a full-scale continuous treatment process, showing that low biomass could achieve reduced effluent PPCP concentrations. These results demonstrated that bioaugmentation may improve PPCP removal using established wastewater infrastructure under conditions of high solids partitioning.

Water Environment Research, 2013

Recent interest in carbon-neutral biofuels has revived interest in co-digestion for methane gener... more Recent interest in carbon-neutral biofuels has revived interest in co-digestion for methane generation. At wastewater treatment facilities, organic wastes may be co-digested with sludge using established anaerobic digesters. However, changes to organic loadings may induce digester instability, particularly for thermophilic digesters. To examine this problem, thermophilic (55 degrees C) co-digestion was studied for two food-industry wastes in semi-continuous laboratory digesters; in addition, the wastes&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; biochemical methane potentials were tested. Wastes with high chemical oxygen demand (COD) content were selected as feedstocks allowing increased input of potential energy to reactors without substantially altering volumetric loadings. Methane generation increased while reactor pH and volatile solids remained stable. Lag periods observed prior to methane stimulation suggested that acclimation of the microbial community may be critical to performance during co-digestion. Chemical oxygen demand mass balances in the experimental and control reactors indicated that all of the food industry waste COD was converted to methane.

The ISME Journal, 2011

Contamination, such as by heavy metals, has frequently been implicated in altering microbial comm... more Contamination, such as by heavy metals, has frequently been implicated in altering microbial community structure. However, this association has not been extensively studied for anaerobic communities, or in freshwater lake sediments. We investigated microbial community structure in the metal-contaminated anoxic sediments of a eutrophic lake that were impacted over the course of 80 years by nearby zinc-smelting activities. Microbial community structure was inferred for bacterial, archaeal and eukaryotic populations by evaluating terminal restriction fragment length polymorphism (TRFLP) patterns in near-surface sediments collected in triplicate from five areas of the lake that had differing levels of metal contamination. The majority of the fragments in the bacterial and eukaryotic profiles showed no evidence of variation in association with metal contamination levels, and diversity revealed by these profiles remained consistent even as metal concentrations varied from 3000 to 27 000 mg kg À1 total Zn, 0.125 to 11.2 lM pore water Zn and 0.023 to 5.40 lM pore water As. Although most archaeal fragments also showed no evidence of variation, the prevalence of a fragment associated with mesophilic Crenarchaeota showed significant positive correlation with total Zn concentrations. This Crenarchaeota fragment dominated the archaeal TRFLP profiles, representing between 35% and 79% of the total measured peak areas. Lake DePue 16S rRNA gene sequences corresponding to this TRFLP fragment clustered with anaerobic and soil mesophilic Crenarchaeota sequences. Although Crenarchaeota have been associated with metal-contaminated groundwater and soils, this is a first report (to our knowledge) documenting potential increased prevalence of Crenarchaeota associated with elevated levels of metal contamination.

PLoS ONE, 2013

The objective of this study was to characterize the morphology, size-distribution, concentration ... more The objective of this study was to characterize the morphology, size-distribution, concentration and genome size of virus-like particles (VLPs) in two acetate-fed Methanosaeta-dominated reactors to better understand the possible correlation between viruses and archaeal hosts. The study reactors were dominated by a single genus of acetoclastic methanogen, Methanosaeta, which was present at 6 to 13 times higher than the combined bacterial populations consisting of Proteobacteria, Firmicutes, and Bacteroidetes. Epifluorescent microscopy showed VLPs concentration of 7.1 ± 1.5×10 7 VLPs/ml and 8.4 ± 4.3×10 7 VLPs/ml in the two laboratory reactors. Observations of no detectable import of VLPs with the reactor feed combined long operational time since the last inocula were introduced suggests that the VLP populations were actively propagating in the reactors. Transmission electron microscopy images showed VLPs with morphology consistent with Siphoviridae in both reactors, and VLPs with morphologies consistent with Myoviridae in one of the reactors. The morphology, size-distribution and genome size of VLPs were distinct between reactors suggesting that unique viral populations inhabited each reactor, though the hosts of these VLPs remain unclear.

Journal of Microbiological Methods, 2003

This study reports a method for optimizing direct counts of bacteria in sediment, designed to red... more This study reports a method for optimizing direct counts of bacteria in sediment, designed to reduce the masking by sediment particles. The protocol was designed to determine appropriate dilution factors by incorporating counting statistics and was used to measure depth-associated changes in microbial abundance in metal-impacted freshwater sediments. We demonstrated a direct method to determine appropriate sample dilution for accurate counting by adding a known amount of cells to the sediment. For accurate counting in our sediment samples, we determined that the average number of bacteria per microscope ocular field must be between 8.5 and 10. This is well below the 30 bacteria/field previously suggested for accurate counting. These results indicate that an optimal dilution rate must be determined before accurate direct counts in sediment can be achieved.

Journal of Geophysical Research, 2008

1] Although sulfate-reducing prokaryotes have long been studied as agents of metals bioremediatio... more 1] Although sulfate-reducing prokaryotes have long been studied as agents of metals bioremediation, impacts of long-term metals exposure on biologically mediated sulfur cycling in natural systems remains poorly understood. The effects of long-term exposure to metal stress on the freshwater sulfur cycle were studied, with a focus on biologic sulfate reduction using a combination of microbial and chemical methods. To examine the effects after decades of adaptation time, a field-based experiment was conducted using multiple study sites in a natural system historically impacted by a nearby zinc smelter (Lake DePue, Illinois). Rates were highest at the most metals-contaminated sites ($35 mmol/cm 3 /day) and decreased with decreased pore water zinc and arsenic contamination levels, while other environmental characteristics (i.e., pH, nutrient concentrations and physical properties) showed little between-site variation. Correlations were established using an artificial neural network to evaluate potentially non-linear relationships between sulfate reduction rates (SRR) and measured environmental variables. SRR in Lake DePue were up to 50 times higher than rates previously reported for lake sediments and the chemical speciation of Zn was dominated by the presence of ZnS as shown by X-ray Absorption Spectroscopy (XAS). These results suggest that long-term metal stress of natural systems might alter the biogeochemical cycling of sulfur by contributing to higher rates of sulfate reduction. (2008), Elevated sulfate reduction in metal-contaminated freshwater lake sediments,

Journal of Geophysical Research, 2008

Little is known about the long-term impacts of metal contamination on the microbiota of anoxic la... more Little is known about the long-term impacts of metal contamination on the microbiota of anoxic lake sediments. In this study, we examined microbial biomass and metals (arsenic, cadmium, chromium, copper, iron, lead, manganese, and zinc) in the sediments of Lake DePue, a backwater lake located near a former zinc smelter. Sediment core samples were examined using two independent measures for microbial biomass (total microscopic counts and total phospholipidphosphate concentrations), and for various fractions of each metal (pore water extracts, sequential extractions, and total extracts of all studied metals and zinc speciation by X-ray absorption fine structure (XAFS). Zinc concentrations were up to 1000 times higher than reported for sediments in the adjacent Illinois River, and ranged from 21,400 mg/kg near the source to 1,680 mg/kg near the river. However, solid metal fractions were not well correlated with pore water concentrations, and were not good predictors of biomass concentrations. Instead, biomass, which varied among sites by as much as two-times, was inversely correlated with concentrations of pore water zinc and arsenic as established by multiple linear regression. Monitoring of other parameters known to naturally influence biomass in sediments (e.g., organic carbon concentrations, nitrogen concentrations, pH, sediment texture, and macrophytes) revealed no differences that could explain observed biomass trends. This study provides strong support for control of microbial abundance by pore water metal concentrations in contaminated freshwater sediments.

Environmental Science & Technology, 2009

Six groundwater monitoring wells from the Field Research Center of the U.S. DOE Environmental Rem... more Six groundwater monitoring wells from the Field Research Center of the U.S. DOE Environmental Remediation Science Program (ERSP) at Oak Ridge, TN, were selected to compose a gradient of pH, nitrate and heavy metal contamination. DNA from the groundwater bacterial community was analyzed with a functional gene array containing 2,006 probes for the detection of genes involved in metal-resistance, sulfate-reduction, contaminant degradation and carbon and nitrogen cycling. Diversity decreased in relation to the level of contamination within each well, and each community exhibited a different distribution of genes. Heatmaps of metal resistance genes and nirK and nirS genes indicate that highly contaminated wells had lower gene diversity, but greater signal intensity for detected genes. Wells with the highest sulfate concentrations had the greatest diversity and signal intensity for dsrAB genes. A greater number of carbon fixation genes (cbbL, cbbM) were detected than fermentation genes (FTHFS) in all wells. A variety of organic contaminant degradation genes were also detected. Results of Mantel tests and canonical correspondence analysis indicate that nitrate, sulfate, pH, uranium and technetium have a significant (p < 0.05) effect on bacterial community structure. This study provides an overall picture of bacterial community structure in contaminated environments across many different functional genes and shows that diversity can vary widely in relation to the degree of contamination.

Biodegradation, 2013

Pharmaceutical and personal care products (PPCPs) discharged with wastewater treatment plant (WWT... more Pharmaceutical and personal care products (PPCPs) discharged with wastewater treatment plant (WWTP) effluents are an emerging surface water quality concern. Biological transformation has been identified as an important removal mechanism during wastewater treatment. The aim of this research was the identification of bacteria with characteristics for potential bioaugmentation to enhance PPCP removal. We report here the cultivation and characterization of bacteria capable of degrading PPCPs to ng/L concentrations. An isolation approach was developed using serial enrichment in mineral medium containing 1 mg/L of an individual PPCP as the sole organic carbon source available to heterotrophs until the original activated sludge inocula was diluted to ~10(-8) of its initial concentration, followed by colony growth on solid R2A agar. Eleven bacteria were isolated, eight that could remove triclosan, bisphenol A, ibuprofen, or 17β-estradiol to below 10 ng/L, one that could remove gemfibrozil to below 60 ng/L, and two that could remove triclosan or E2, but not to ng/L concentrations. Most bacterial isolates degraded contaminants during early growth when grown utilizing rich carbon sources and were only able to degrade the PPCPs on which they were isolated. Seven of the bacterial isolates were sphingomonads, including all the triclosan and bisphenol A degraders and the ibuprofen degrader. The study results indicate that the isolated bacteria may have a positive influence on removal in WWTPs if present at sufficient concentrations and may be useful for bioaugmentation.

Applied and Environmental Microbiology, 2003

Diversity, habitat range, and activities of sulfate-reducing prokaryotes within hot springs in Ye... more Diversity, habitat range, and activities of sulfate-reducing prokaryotes within hot springs in Yellowstone National Park were characterized using endogenous activity measurements, molecular characterization, and enrichment. Five major phylogenetic groups were identified using PCR amplification of the dissimilatory sulfite reductase genes (dsrAB) from springs demonstrating significant sulfate reduction rates, including a warm, acidic (pH 2.5) stream and several nearly neutral hot springs with temperatures reaching 89°C. Three of these sequence groups were unrelated to named lineages, suggesting that the diversity and habitat range of sulfate-reducing prokaryotes exceeds that now represented in culture.

Environmental Science & Technology, 2014

The removal of the potent endocrine-disrupting estrogen hormone, 17α-ethinylestradiol (EE2), in m... more The removal of the potent endocrine-disrupting estrogen hormone, 17α-ethinylestradiol (EE2), in municipal wastewater treatment plant (WWTP) activated sludge (AS) processes can occur through biodegradation by heterotrophic bacteria growing on other organic wastewater substrates. Different kinetic and metabolic substrate utilization conditions created with AS bioselector processes can affect the heterotrophic population composition in AS. The primary goal of this research was to determine if these changes also affect specific EE2 biodegradation kinetics. A series of experiments were conducted with parallel bench-scale AS reactors treating municipal wastewater with estrogens at 100-300 ng/L concentrations to evaluate the effect of bioselector designs on pseudo first-order EE2 biodegradation kinetics normalized to mixed liquor volatile suspended solids (VSS). Kinetic rate coefficient (kb) values for EE2 biodegradation ranged from 5.0 to 18.9 L/g VSS/d at temperatures of 18 °C to 24 °C. EE2 kb values for aerobic biomass growth at low initial food to mass ratio feeding conditions (F/Mf) were 1.4 to 2.2 times greater than that from growth at high initial F/Mf. Anoxic/aerobic and anaerobic/aerobic metabolic bioselector reactors achieving biological nutrient removal had similar EE2 kb values, which were lower than that in aerobic AS reactors with biomass growth at low initial F/Mf. These results provide evidence that population selection with growth at low organic substrate concentrations can lead to improved EE2 biodegradation kinetics in AS treatment.