Jamie Hestekin

The Separative Bioreactor: A Continuous Separation Process for the Simultaneous Production and Direct Capture of Organic Acids

Abstract The replacement of petrochemicals with biobased chemicals requires efficient bioprocesses, biocatalysis, and product recovery. Biocatalysis (e.g., enzyme conversion and fermentation) offers an attractive alternative to chemical processing because biocatalysts utilize renewable feedstocks under benign reaction conditions. One class of chemical products that could be produced in large volumes by biocatalysis is organic acids. However, biocatalytic reactions to produce organic acids typically result in only dilute concentrations of the product because of product inhibition and acidification that drives the reaction pH outside of the optimal range for the biocatalyst. Buffering or neutralization results in formation of the acid salt rather than the acid, which requires further processing to recover the free acid product. To address these barriers to biocatalytic organic acid production, we developed the “separative bioreactor” based on resin wafer electrodeionization, which is an electrodeionization platform that uses resin wafers fabricated from ion exchange resins. The separative bioreactor simultaneously separates the organic acid from the biocatalyst as it is produced, thus it avoids product inhibition enhancing reaction rates. In addition, the separative bioreactor recovers the product in its acid form to avoid neutralization. The instantaneous separation of acid upon formation in the separative bioreactor is one of the first truly one‐step systems for producing organic acids. The separative bioreactor was demonstrated with two systems. In the first demonstration, the enzyme glucose fructose oxidoreductase (GFOR) was immobilized in the reactor and later regenerated in situ. GFOR produced gluconic acid (in its acid form) continuously for 7 days with production rates up to 1000 mg/L/hr at >99% product recovery and GFOR reactivity >30 mg gluconic acid/mg GFOR/hour. In the second demonstration, the E. coli strain CSM1 produced lactic acid for up to 24 hours with a productivity of >200 mg/L/hr and almost 100% product recovery.

Application of Wafer-Enhanced Electrodeionization in a Continuous Fermentation Process to Produce Butyric Acid with Clostridium tyrobutyricum

Butryic acid is an organic acid which can be produced from Clostridium tyrobutyricum. This organic acid has many applications in food and perfumes as well serving as the first step in a two-step butanol production process. However, the fermentation is product inhibited as well as producing by-products of acetic acid and lactic acid. Electrodialysis and electrodeionization were explored as ways to separate butyric acid from a fermentation broth, in situ. For butyric acid system, the current resistance for ED was almost half that of EDI indicating that ED might be a better option for a pure component separation. However, in a simulated broth containing butyric, lactic, and acetic acid, the opposite trend was found to be true. These results were used to design a fermentation experiment where ED and EDI were used to separate butyric acid from an actual fermentation. It is shown that the percentage of butyric acid (compared to other organic acids) is 84%, 85%, and 92% for no separation, ED, and EDI, respectively. Further, the productivity rate is enhanced by almost 220% when comparing EDI to no separation indicating that it may make sense to use EDI for the separation of butyric acid from a Clostridium tyrobutryicum fermentation.

Synergistic Effect of Abrasive and Sonication for Release of Carbohydrate and Protein from Algae

While algae have demonstrated significant potential as a raw material due to the high intracellular concentration of carbohydrates and proteins, a primary limitation as a biofuel feedstock is due to the fact that an economically feasible method of extraction has yet to be offered. Algae samples, acquired from a local waste treatment facility, were combined with abrasive materials and subjected to ultrasonication for specific time intervals. It was found that the synergistic effect of sonication in the presence of abrasive material, such as silicon beads or sand, could extract adequate protein and carbohydrate to be utilized in fermentation processes.

Wafer Chemistry and Properties for Ion Removal by Wafer Enhanced Electrodeionization

Electrodeionization is a widely used technology to produce ultrapure water for various applications such as cooling towers, water reclamation for micro-fabrication, and pharmaceuticals. Wafer Enhanced- Electrodeionization (WE-EDI) is a technology which immobilizes resins into wafers allowing for a significant expansion in applications due to a decrease in internal and external channeling and leakage. Although WE-EDI allows for a wide variety of applications in low concentration and selective ion removal, there have been few studies on the effects of various processing variables on WE-EDI performance. This paper investigates the effects of different variables in wafer performance including porosity, capacity, permeability, and ion exchange bead type. Experimental data and predictive modeling shows that thickness and capacity have little effect on the ability of the wafer to enhance cation transport while the ratio of anion exchange to cation exchange resin, the amount of polymer used to bind the resins, and selectivity of the resin beads have a much greater effect. From the experimental and modeling results, it is recommended that the bead chemistry, especially the equilibrium constant K, should be the main consideration for specific ion removal applications.

Glucose Driven Nanobiopower Cells for Biomedical Applications

Power supply is an important aspect of micronanobiomedical devices. Implantable devices are required to stay inside of the body for longer period of time to provide continuous monitoring, detection, and therapeutics. The constricted areas of the human body, accessed by these devices, imply that the power source should not increase the payload significantly. Conventional on-board power sources are big, as compared with the device themselves, or involve wire-outs. Both provisions are liable to develop complications for sensor/actuator implant packaging. A plausible approach can be innovative solutions for sustainable bio-energy harvesting. Research studies have reported feasibility of miniature power sources, running on redox reactions. The device design, reported in this study, is a combination of nano-engineered composites and flexible thin film processing to achieve high density packaging. Of which, the end goal is production of energy for sensor applications. Both the bio-electrodes were successfully functionalized by amide bond cross-linkage between the carbon nanotube surface and the enzyme molecules: catalase and glucose oxidase for cathode and anode, respectively. The nanocomposite based biopower cell was evaluated as a steady power supply across the physiological range of glucose concentration. The power cell was able to deliver a steady power of 3.2 nW at 85 mV for glucose concentrations between 3 mM and 8 mM. Electron microscopy scanning of the functionalized electrode surface and spectroscopic evaluation of nanotube surface were used for evaluation of the biofunctionalization technique. Cyclic voltametric (CV) scans were performed on the cathodic and anodic half cells to corroborate bioactivity and qualitatively evaluate the power cell output against the redox peaks on the CV scans. The importance of these results has been discussed and conclusions have been drawn pertaining to further miniaturization (scale down) of the cell.

PEG-mimetic peptoid reduces protein fouling of polysulfone hollow fibers.

Biofouling is a persistent problem for membranes exposed to blood or other complex biological fluids, affecting surface structure and hindering performance. In this study, a peptoid with 2-methoxyethyl (NMEG5) side chains was immobilized on polysulfone hollow fiber membranes to prevent protein fouling. The successful attachment of NMEG5 to the polysulfone surface was confirmed by X-ray photoelectron spectroscopy and an increase in hydrophilicity was confirmed by contact angle analysis. The NMEG5-modified surface was found to resist fouling with bovine serum albumin, lysozyme, and adsorbed significantly less fibrinogen as compared with other published low-fouling surfaces. Due to the low fouling nature and increased biocompatibility of the NMEG5 coated membranes, they have potential applicability in numerous biomedical applications including artificial lungs and hemodialysis.

Economic comparison of pressure driven membrane processes to electrically driven processes for use in hydraulic fracturing

ABSTRACT Hydraulic fracturing has become a reliable source for oil and natural gas, yet widespread use has led to significant issues with water consumption and sustainable sourcing. Research into the reuse of produced water and flowback water have focused on mitigating water demand in this industry through membrane separation technology. In general, nanofiltration and reverse osmosis have been thought to be more economically viable for the treatment of produced and flowback water at high flowrates. However, electrodialysis and electrodeionization are generally more flexible for production of produced water and brackish water for reuse in fracturing operations when contaminant concentrations in produced water and flowback water are low. Electrodialysis and electrodeionization can also significantly reduce wastewater produced from water treatment, decreasing the amount of water that must be disposed by deep well injection. Thus, there are many cases where electrically driven processes compete well with pressure driven processes due to high water recovery and each case must be analyzed in terms of water quality variability and overall desired water treatment rate. This paper finds that at low ion concentration of inlet water, electrodialysis and electrodeionization are energy-efficient, cost-effective attractive technologies for water recovery.

Production of recombinant protein in Escherichia coli cultured in extract from waste product alga, Ulva lactuca

This study examined the potential for waste product alga, Ulva lactuca, to serve as a media component for recombinant protein production in Escherichia coli. To facilitate this investigation, U. lactuca harvested from Jamaica Bay was dried, and nutrients acid extracted for use as a growth media. The E. coli cell line BL21(DE3) was used to assess the effects on growth and production of recombinant green fluorescent protein (GFP). This study showed that media composed of acid extracts without further nutrient addition maintained E. coli growth and recombinant protein production. Extracts made from dried algae lots less than six‐months‐old were able to produce two‐fold more GFP protein than traditional Lysogeny Broth media.