Kenneth F Reardon

Kenneth F Reardon
Colorado State University | CSU · Department of Chemical & Biological Engineering

PhD

About

186
Publications
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Publications

Publications (186)
Article
Anaerobic digesters produce renewable energy from organic wastes, including animal wastes. However, ammonia toxicity stemming from the nitrogen content of animal wastes reduces the feasibility of the process. Approaches for stripping ammonia and recovering it via the use of strong mineral acids have disadvantages. Here, we evaluate a process that i...
Article
Full-text available
Microalgae are promising sources of fuels and other chemicals. To operate microalgal cultivations efficiently, process control based on monitoring of process variables is needed. On-line sensing has important advantages over off-line and other analytical and sensing methods in minimizing the measurement delay. Consequently, on-line, in-situ sensors...
Article
Full-text available
The conversion of carbohydrates in biomass via fermentation is an important component of an overall strategy to decarbonize the production of fuels and chemicals. Owing to the cost and resources required to produce biomass hydrolysates, the economic and environmental sustainability of these fermentation processes requires that they operate with hig...
Article
One strategy to increase the yield of desired fermentation products is to redirect substrate carbon from biomass synthesis. Non-genetic approaches to alter metabolism may have advantages of general applicability and simple control. The goal of this study was to identify and evaluate chemicals for their ability to inhibit the growth of Saccharomyces...
Article
Polyacrylonitrile (PAN) based carbon nanofiber (CNF) papers have unique physicochemical properties including flexibility, good electrical conductivities, and excellent mechanical properties for supercapacitor electrodes. However, their surface-to-weight ratios and density of active sites on the surface are much poorer than those of other active car...
Article
Precise control over bioreactor operation is desired for optimal productivity and product quality, and there is an increased drive to automation in biomanufacturing. All of these goals require sensors, not only of the basic parameters of temperature, pH, and dissolved oxygen, but of the biomass and substrate concentrations, which directly determine...
Article
High emissions of particulate matter from diesel engines presents a serious risk to human health and the environment. The addition of oxygenated molecules to diesel fuels has been shown to reduce soot formation during combustion. Polyoxymethylene ethers (POMEs) are a novel class of oxygenated molecules that can be produced from biomass and that hav...
Article
Methyl-terminated polyoxymethylene ethers (MM-POMEs), having the formula CH3O−(CH2O)n−CH3 (n = 3−5), are a high-cetane, low-sooting group of oxygenates that have recently attracted attention as potential diesel blendstocks. Despite these attractive fuel properties, MM-POMEs have shortcomings due to their low energy density and high water solubility...
Article
Conversion of organic wastes to fatty acids rather than methane through anaerobic digestion-based technologies has considerable promise. However, the relationships between microbiome structure and fatty acids produced from cellulosic feedstocks are not well understood. This study investigated the nature of those relationships for anaerobic digester...
Chapter
The production of pharmaceuticals, industrial chemicals, and food ingredients from biotechnological processes is a vast and rapidly growing industry. While advances in synthetic biology and metabolic engineering have made it possible to produce thousands of new molecules from cells, few of these molecules have reached the market. The traditional me...
Article
Current methods of sampling pore water from soil columns to determine solute concentrations are slow and require relatively large volumes. Accordingly, an electromagnetically-vibrated (EMV) solid phase microextraction (SPME) device with negligible mass loss and flow disturbance was evaluated to determine temporal and spatial distributions of solute...
Article
Full-text available
Alcohols are attractive fuel blendstocks for spark ignition engines due to their high octane values and potentially positive influence on performance and emission. Although methanol, ethanol, and butanol have been widely studied, other biomass-derived alcohols may have similar or better properties. However, it is not feasible to experimentally inve...
Article
Supplementing petroleum fuels with sustainable and renewable alternatives is a good option for increasing the sustainability of transportation fuels. Alcohols are particularly attractive blendstocks for spark ignition engines, mainly due to their desirable fuel properties including high octane, evaporative cooling, and reduced sooting propensity. A...
Chapter
This chapter provides an overview on the available and future sensor technology for single‐use bioreactors. A bioreactor can be considered to be a three‐phase system, consisting of a liquid, gas, and solid phase (cells). Sensors for monitoring each of these phases exist. However, because of their relevance for disposable bioreactors, the chapter is...
Article
Biofuels can contribute to reducing greenhouse gas emissions from the transportation sector. Ethanol is the main additive for gasoline in the United States, and gasoline containing 10 vol% ethanol is the most commonly used transportation fuel. However, the vapor pressure of these blends is significantly higher than gasoline, which contributes to ev...
Article
Lactic acid is a valuable organic acid that can be produced by fermentation of renewable sugar. Lactate productivity can be increased by retaining cells within the reactor, enabling continuous operation with higher cell concentrations. Biofilms are an inexpensive cell immobilization method. While much is known about the differences in physiology an...
Article
After fermentation, the concentration of bioethanol is only 8–12 wt%. To produce anhydrous ethanol fuel, a significant amount of energy is required for separation and dehydration. Once the azeotrope composition is reached, distillation can no longer be exploited for purification and more expensive methods must be used. Replacing anhydrous ethanol f...
Article
Water removal during the production of bio-ethanol is highly energy intensive. At the azeotropic point, the mixture can no longer be separated via fractional distillation, thus expensive and energy intensive methods are required for further purification. Hence, there is an interest in using hydrous ethanol at the azeotropic point to improve the ene...
Article
Full-text available
Background Bioelectrochemical systems (BESs) harness electrons from microbial respiration to generate power or chemical products from a variety of organic feedstocks, including lignocellulosic biomass, fermentation byproducts, and wastewater sludge. In some BESs, such as microbial fuel cells (MFCs), bacteria living in a biofilm use the anode as an...
Article
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Interactions among members of microbial consortia drive the complex dynamics in soil, gut, and biotechnology microbiomes. Proteomic analysis of defined co-cultures of well-characterized species provides valuable information about microbial interactions. We used a label-free approach to quantify the responses to co-culture of two model bacterial spe...
Article
While microalgae are a promising feedstock for production of fuels and other chemicals, a challenge for the algal bioproducts industry is obtaining consistent, robust algae growth. Algal cultures include complex bacterial communities and can be difficult to manage because specific bacteria can promote or reduce algae growth. To overcome bacterial c...
Conference Paper
Biofuels can contribute to reducing greenhouse gas emissions from the transportation sector. While the use of a neat alcohol as a fuel for spark-ignition engines would displace large amounts of petroleum, neat alcohols cannot provide the distillation temperature range required for smooth driveability and often exhibit high enthalpies of vaporizatio...
Article
Full-text available
Background and aims Some rhizosphere microbes, such as plant growth-promoting rhizobacteria (PGPR), can alleviate plant drought stress and improve water use efficiency and productivity under drought conditions. The aims of this study are: 1) isolation and characterization of PGPRs from the rhizosphere of Arabidopsis plants that could improve drough...
Article
Modern bioprocess monitoring demands sensors that provide on-line information about the process state. In particular, sensors for monitoring bioprocesses carried out in single-use bioreactors are needed because disposable systems are becoming increasingly important for biotechnological applications. Requirements for the sensors used in these single...
Article
Grain sorghum is an important staple food crop grown globally while sweet sorghum is increasingly considered as a promising biofuel feedstock. Biofuels are the major economic products from the processing of large quantities of biomass, which is currently being utilized to make value-added products in the biorefinery approach. To date, these value-a...
Article
Consistent cultivation of robust algae cultures is a major challenge at large scales due to pests that can severely detract from algae productivity. To optimize algae productivity, understanding algae culture ecology will need significant advancement of pest management practices. To date, there is limited knowledge about bacterial pests that affect...
Article
The use of spectroscopic sensors for bioprocess monitoring is a powerful tool within the process analytical technology (PAT) initiative of the US Food and Drug Administration. Spectroscopic sensors enable the simultaneous real-time bioprocess monitoring of various critical process parameters including biological, chemical, and physical variables du...
Article
Full-text available
Although it is well known that diet is one of the major modulators of the gut microbiome, how the major components of diet shape the gut microbial community is not well understood. Here, we developed a simple system that allows the investigation of the impact of given compounds as supplements of the diet on the termite gut microbiome. The 16S rRNA...
Article
We examine the effect of diel light:dark cycles (12:12 LD) on the production of free fatty acids (FFAs) in Synechocystis sp. PCC 6803. Our results show that FFA titers in FFA producing strains of Synechocystis were significantly reduced in 12:12 LD compared to continuous light. On the transcriptional level, we saw no significant changes of the fatt...
Article
: Process monitoring, which can be defined as the measurement of process variables with the smallest possible delay, is combined with process models to form the basis for successful process control. Minimizing the measurement delay leads inevitably to employing online, in situ sensors where possible, preferably using noninvasive measurement methods...
Article
The ability to measure all process variables is of great importance in the field of bioprocess monitoring and control, and continuous, real-time measurements are highly desired. The more complete and real-time the measurements are, the more stable, reproducible, and efficient the process can be, leading to reproducibly high quality products. This a...
Article
The primary focus of research and development toward algal biofuels has been the production of fuel from the lipid fraction, with the non-lipid biomass used for production of biogas, electricity, animal feed, or fertilizer. Since the non-lipid fraction comprises approximately half of the algal biomass, the development of processes to produce additi...
Article
Aims: The aim of this study was to evaluate effects of PGPR (plant growth-promoting rhizobacteria) isolated from rainforest soil on different plants under limited nitrogen conditions. Methods and results: Bacterial isolates from a Peruvian rainforest soil were screened for plant growth-promoting effects on Arabidopsis (Col-0). Four selected isol...
Article
Full-text available
The study of the interactions between plants and their microbial communities in the rhizosphere is important for developing sustainable management practices and agricultural products such as biofertilizers and biopesticides. Plant roots release a broad variety of chemical compounds to attract and select microorganisms in the rhizosphere. In turn, t...
Chapter
To date, research, development, and commercialization within the bioenergy industry has focused on the production of biofuels, with any unconverted biomass used for production of electricity, biogas, animal feed, or fertilizer. However, both the economics and the environmental impacts of biofuel production could be improved by developing processes...
Article
A total internal reflection photoluminescence (TIRPh) device employing an easily fabricated PMMA/PDMS waveguide system provides a detection limit comparable to the best reported results but without using an excitation filter. The optical mechanism is similar to total-internal-reflection-fluorescence (TIRF) but uses a ruthenium-based phosphorescent...
Article
Full-text available
We evaluated a sequential elution protocol from immobilized metal affinity chromatography (SIMAC) employing gallium-based immobilized metal affinity chromatography (IMAC) in conjunction with titanium-dioxide-based metal oxide affinity chromatography (MOAC). The quantitative performanceof this SIMAC enrichment approach, assessed in terms of repeatab...
Article
Microalgal cultivations present challenges for monitoring and process control posed by their large scale and the likelihood that they will be composed of multiple species. Cell concentration is a fundamental parameter in any cultivation but is typically measured using off-line methods that may be time-consuming, laborious, or subject to interferenc...
Article
Full-text available
Sulfate-reducing permeable reactive zones (SR-PRZs) are microbially-driven anaerobic systems designed for the removal of heavy metals and sulfate in mine drainage. Environmental perturbations, such as oxygen exposure, may adversely affect system stability and long-term performance. The objective of this study was to examine the effect of two succes...
Article
The deconstruction of lignin to enhance the release of fermentable sugars from plant cell walls presents a challenge for biofuels production from lignocellulosic biomass. The discovery of novel lignin-degrading enzymes from bacteria could provide advantages over fungal enzymes in terms of their production and relative ease of protein engineering. I...
Article
Large cultivations of microalgae will benefit from on-line monitoring to achieve process control and improved productivity. This monitoring requires reliable sensors for on-line, in situ measurement of both physicochemical and biological process variables. Although standard industrial sensors can be used for many physicochemical variables, monitori...
Article
Full-text available
The feasibility of the ideal adsorbed solution theory (IAST) in reducing the complexity associated with predicting the sorption behaviors of 12 neutral organic compounds (NOCs) contained in complex mixtures as a fewer number (four to six) of pseudocompounds (groups of compounds) to simulated aquifer sorbents was investigated. All sorption isotherms...
Article
Diets shape the animal gut microbiota, although the relationships between diets and the structure of the gut microbial community are not yet well understood. The gut bacterial communities of Reticulitermes flavipes termites fed on four individual plant biomasses with different degrees of recalcitrance to biodegradation were investigated by 16S rRNA...
Article
Full-text available
Background Inorganic phosphate (Pi) is a critical nutrient for all life and is periodically limiting in marine and freshwater provinces, yet little is understood how organisms acclimate to fluctuations in Pi within their environment. To investigate whole cell adaptation, we grew Synechocystis sp. PCC6803, a model freshwater cyanobacterium, in 3%, a...
Data
Growth curves for Synechocystis PCC6803 grown in Pi replete medium (green circles), 3% Pi medium (red triangles), and 0.3% Pi medium (purple diamonds). All cultures were in early stationary phase upon harvesting. Figure S2. Representation of the broad functional categories associated with Synechocystis PCC6803 proteins identified in this study. Fig...
Article
Protein phosphorylation has been widely documented as a key regulatory and signaling mechanism associated with many cardiac diseases. Recent advances in phosphoproteomic technologies such as phosphopeptide enrichment, novel mass spectrometry applications, and bioinformatic tools have resulted in high-throughput identification and quantitation of pr...
Article
Guidelines for submitting commentsPolicy: Comments that contribute to the discussion of the article will be posted within approximately three business days. We do not accept anonymous comments. Please include your email address; the address will not be displayed in the posted comment. Cell Press Editors will screen the comments to ensure that they...
Article
Sulfate-reducing permeable reactive zones (SR-PRZs) depend upon a complex microbial community to utilize a lignocellulosic substrate and produce sulfides, which remediate mine drainage by binding heavy metals. To gain insight into the impact of the microbial community composition on the startup time and pseudo-steady-state performance, functional g...
Article
Full-text available
The concept of using lumping analysis to reduce the complexity associated with the sorption of 12 neutral organic compounds (NOCs) comprising complex mixtures to simulated aquifer sorbents was evaluated. The sorbates covered a wide range of octanol–water partitioning coefficients, K ow (i.e., À0:24 ≤ log K ow ≤ 4:23), and the sorbents included diff...
Article
The soy-derived phytoestrogen genistein (GEN) has received attention for its potential benefits on the cardiovascular system by providing direct protection to cardiomyocytes against pathophysiological stresses. Here, we employed a proteomic approach to study the concentration-dependent effects of GEN treatments on cardiomyocytes. Cultured HL-1 card...
Article
An optical fiber enzymatic biosensor was formed by immobilizing cells containing atrazine chlorohydrolase to the surface of a pH-sensitive optode. This enzyme catalyzes the dechlorination of atrazine, releasing hydrochloric acid and creating a signal response from the optode that was proportional to the atrazine concentration. Biosensors capable of...
Chapter
Full-text available
Carbon storage in terrestrial ecosystems is contingent upon the natural resistance of plant cell wall polymers to rapid biological degradation. Nevertheless, certain microorganisms have evolved remarkable means to overcome this natural resistance. Lignocellulose decomposition by microorganisms comprises an essential step in closing the loop of the...
Article
Full-text available
Pentachlorophenol (PCP) was studied as a model recalcitrant compound for a sequential chemical oxidation and biodegradation treatment, in a continuous laboratory-scale system that combined a Fenton's chemical reactor and a packed-bed bioreactor. PCP degradation and dechlorination were observed in the Fenton's reactor at a residence time of 1.5 h, a...
Article
Environmental releases and fate of steroid sex hormones from livestock and wastewater treatment plants are of increasing regulatory concern. Despite the detection of these hormones in manures, biosolids, and the environment, little attention has been paid to characterization of fecal bacteria capable of hormone degradation. The enrichments of (swin...
Article
Passive biological systems such as sulfate-reducing biochemical reactors have shown promise for treatment of mine drainage because of their low cost, minimal maintenance, and constructability in remote locations. However, few criteria exist for their design and operation. In particular, the impact of the choice of carbon substrate is poorly underst...
Article
Full-text available
The sorption of 12 neutral organic compounds (NOCs) contained in mixtures to both hydrophilic mineral surfaces [uncoated, iron (hydr)oxide-coated, and aluminum (hydr)oxide-coated sands] and humic acid-mineral complexes with different fractions of organic carbon, f oc (¼ 0:051, 0.119, and 0.221%) was evaluated using batch equilibrium sorption tests....
Article
Laccases are a class of multi-copper oxidases (MCOs) that catalyze the one-electron oxidation of four equivalents of a reducing substrate, with the concomitant four-electron reduction of dioxygen to water. They can catalyze a multitude of reactions, including the degradation of polymers and oxidative coupling of phenolic compounds, positioning them...
Article
Full-text available
There is increasing interest in using microalgae as a lipid feedstock for the production of biofuels. Lipids used for these purposes are triacylglycerols that can be converted to fatty acid methyl esters (biodiesel) or decarboxylated to "green diesel." Lipid accumulation in most microalgal species is dependent on environmental stress and culturing...
Chapter
Introduction Disposable Sampling Systems for Ex Situ Analysis Direct Optical Sensing Optical Chemosensors In Situ Microscopy Other Optical Sensors Electrochemical Sensors Conductivity and Capacitance Sensors Sensors Based on Ultrasound Disposable Pressure Sensors Conclusions
Conference Paper
Full-text available
The commercialization of cellulosic biofuels requires the cost-effective release of fermentable sugars from plant biomass. Since cellulose in plant cell walls is intricately interlinked with hemicellulose and lignin, access to the fermentable sugars can only be achieved by the removal of lignin. Current physicochemical pretreatment technologies inv...
Article
Here, we report the validation and advancement of a high-throughput method for fingerprinting the active members of a microbial community. This method, termed active community profiling (ACP), provides information about both the composition and the activity of mixed microbial cultures via comparative measurements of amplified 16S rRNA (RNA) and 16S...
Article
Measurements of pollutants such as toluene are critical for the characterization of contaminated sites and for the monitoring of remediation processes and wastewater treatment effluents. Fiber optic enzymatic biosensors have the potential to provide cost-effective, real time, continuous, in situ measurements. In this study, a fiber optic enzymatic...
Article
One of the major aims of bioprocess engineering is the real-time monitoring of important process variables. This is the basis of precise process control and is essential for high productivity as well as the exact documentation of the overall production process. Infrared spectroscopy is a powerful analytical technique to analyze a wide variety of or...
Article
Full-text available
A newly developed electromagnetically vibrated Solid-Phase Microextraction (SPME) device for extracting 1, 4-dichlorobenzene and toluene from aqueous matrices was evaluated in terms of sorption equilibrium time, precision, and detection level relative to three other more conventional extraction techniques involving SPME, viz., static, magnetic stir...
Article
A multi-channel fiber optic photoluminescence system was developed for real time, in situ and continuous quantitative monitoring of chemical parameters in analytes, with the advantages of ease of use and low cost in manufacturing. The system sequentially excites 8 optodes and measures the resulting photoluminescence with a single photomultiplier. T...
Article
Full-text available
Cellulose degradation, fermentation, sulfate reduction, and methanogenesis are microbial processes that coexist in a variety of natural and engineered anaerobic environments. Compared to the study of 16S rRNA genes, the study of the genes encoding the enzymes responsible for these phylogenetically diverse functions is advantageous because it provid...
Conference Paper
Halogenated hydrocarbons are among the most common environmental contaminants in groundwater, due to their widespread use and their recalcitrance to natural attenuation. Halogenated alkanes (1,2-dichloroethane, 1,2-dibromoethane) could cause health problems and could be found in most environmental groundwater monitoring sites. Traditional laborator...