Quantification of the oxygen uptake rate in a dissolved oxygen controlled oscillating jet-driven microbioreactor

β-Sitosterol Bioconversion in Small-Scale Devices: From Microtiter Plates to Microfluidic Reactors

Small-scale devices are routinely used as low-cost miniaturized bioreactors due to the large number of experiments that can be conducted simultaneously under similar conditions and replicate all functions of bench-scale reactors at dramatically smaller volumes. Microtiter plates, due to the standard footprint, can be integrated with liquid handling systems and associated equipment, expanding considerably their application and use. However, care has to be taken to operate the microtiter plates in optimized mixing and oxygen transfer conditions, preventing medium evaporation in prolonged experiment runs. Recently, to increase data quality, microbioreactors have emerged as an alternative to shaken systems. These systems offer higher degree of control over key process variables and when combined with sensing technology increase dramatically the reliability of translational process data. In this chapter, we describe the production of 4-androstene-3,17-dione (androstenedione (AD)), a key pharmaceutical steroid intermediate, by Mycobacterium sp. NRRL B-3805 via the selective cleavage of the side-chain of β-sitosterol using 24-well microtiter plates and microfluidic microbioreactors.

The effect of sludge retention time (SRT) on the Nitrifier typical kinetics at ambient temperature under the low ammonia density

Sludge retention time (SRT) regulation is one of the essential management techniques for refined control of the main-sidestream treatment process under the low ammonia density. It is indispensable to understand the effect of SRTs changes on the Nitrifier kinetics to obtain the functional separation of the Nitrifier and the refined control of the nitrification process. In this study, Nitrifier was cultured with conditions of 35 ± 0.5 °C, pH 7.5 ± 0.2, DO 5.0 ± 0.5 mg-O/L, and SRTs were controlled for 40 d, 20 d, 10 d, and 5 d. The net growth rate (μ_m), decay rate (b), specific growth rate (μ), the yield of the Nitrifier (Y_A), temperature parameter (T_A), and inhibition coefficient (K_I) have been measured and extended with the SRT decreases. Instead, the half-saturation coefficient (K_S) decreased. In addition, the limited value of pH inhibition occurs (pH_UL), and the pH of keeping 5% maximum reaction rate (pH_LL) was in a relatively stable state. The trade of kinetics may be induced by the change of species structure of Nitrifier. The Nitrosomonas proportion was increased, and the Nitrospira was contrary with the SRT decreasing. It is a match for the functional separation of Nitrifier when SRTs was 20 d at ambient temperature under the low ammonia density. The kinetics of ammonia-oxidizing organisms (AOO) and nitrite-oxidizing organisms (NOO) in Nitrifier under different SRT conditions should be measured respectively to the refined control of the partial nitrification process in future study.

Wearable patch delivery system for artificial pancreas health diagnostic-therapeutic application: A review

The advanced stimuli-responsive approaches for on-demand drug delivery systems have received tremendous attention as they have great potential to be integrated with sensing and multi-functional electronics on a flexible and stretchable single platform (all-in-one concept) in order to develop skin-integration with close-loop sensation for personalized diagnostic and therapeutic application. The wearable patch pumps have evolved from reservoir-based to matrix patch and drug-in-adhesive (single-layer or multi-layer) type. In this review, we presented the basic requirements of an artificial pancreas, surveyed the design and technologies used in commercial patch pumps available on the market and provided general information about the latest wearable patch pump. We summarized the various advanced delivery strategies with their mechanisms that have been developed to date and representative examples. Mechanical, electrical, light, thermal, acoustic and glucose-responsive approaches on patch form have been successfully utilized in the controllable transdermal drug delivery manner. We highlighted key challenges associated with wearable transdermal delivery systems, their research direction and future development trends.

Practical and Durable Flexible Strain Sensors Based on Conductive Carbon Black and Silicone Blends for Large Scale Motion Monitoring Applications

Presented is a flexible capacitive strain sensor, based on the low cost materials silicone (PDMS) and carbon black (CB), that was fabricated by casting and curing of successive silicone layers—a central PDMS dielectric layer bounded by PDMS/CB blend electrodes and packaged by exterior PDMS films. It was effectively characterized for large flexion-angle motion wearable applications, with strain sensing properties assessed over large strains (50%) and variations in temperature and humidity. Additionally, suitability for monitoring large tissue deformation was established by integration with an in vitro digestive model. The capacitive gauge factor was approximately constant at 0.86 over these conditions for the linear strain range (3 to 47%). Durability was established from consistent relative capacitance changes over 10,000 strain cycles, with varying strain frequency and elongation up to 50%. Wearability and high flexion angle human motion detection were demonstrated by integration with an elbow band, with clear detection of motion ranges up 90°. The device’s simple structure and fabrication method, low-cost materials and robust performance, offer promise for expanding the availability of wearable sensor systems.

Difference of respiration-based approaches for quantifying heterotrophic biomass in activated sludge of biological wastewater treatment plants

Estimation of heterotrophic biomass concentration in activated sludge is essential to the design, operation and management of activated sludge process for wastewater treatment plants (WWTPs), and many methods have been developed for such a purpose. In this study, three respiration-based methods: the Exponential-growth-rate-based method (Exp-M), the Maximum-respiration-rate-based method (Max-M) and the Endogenous-respiration-rate-based method (End-M), which are frequently used for determining kinetic parameters in activated sludge models, were comparatively examined using experimental results from both full-scale municipal WWTPs and laboratory-scale reactors. Our study revealed the pros and cons of each method, which is valuable for method selection in different applications. The End-M can estimate all the fraction of biomass. However, the proper control of measuring condition is of great challenge. The Exp-M can only determine the exponential growth part of biomass as conditions employed during measuring may make a considerable part of biomass in a nongrowth status, resulting underestimation or even failure of calculation. The Max-M can determine the viable biomass including the nongrowth part, and it is recommended for rapid assessment of biomass. The Max-M was modified after the introduction of a coefficient SOUR_SRT=0 (the specific oxygen utilization rate when the sludge retention time was assumed zero) and was validated by using the experimental results reported in previous studies. Because of its simplicity and much improved accuracy, the modified Max-M method is able to provide more useful information about activated sludge compositions and has a promising application potential in wastewater treatment plants.

Application of a multiphase microreactor chemostat for the determination of reaction kinetics of Staphylococcus carnosus

Bioreactors at the microliter scale offer a promising approach to accelerate bioprocess development. Advantages of such microbioreactors include a reduction in the use of expensive reagents. In this study, a chemostat operation mode of a cuvette-based microbubble column bioreactor made of polystyrene (working volume of 550 µL) was demonstrated. Aeration occurs through a nozzle (Ø ≤ 100 µm) and supports submerged whole-cell cultivation of Staphylococcus carnosus. Stationary concentrations of biomass and glucose were determined in the dilution rate regime ranging from 0.12 to 0.80 1/h with a glucose feed concentration of 1 g/L. For the first time, reaction kinetics of S. carnosus were estimated from data obtained from continuous cultivation. The maximal specific growth rate (µ_max = 0.824 1/h), Monod constant (K_S = 34 × 10^{- 3}g_S/L), substrate-related biomass yield coefficient (Y_X/S = 0.315 g_CDW/g_S), and maintenance coefficient (m_S = 0.0035 g_S/(g_CDW·h)) were determined. These parameters are now available for further studies in the field of synthetic biology.

Bioprocess microfluidics: applying microfluidic devices for bioprocessing

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Microfluidic devices as novel bioprocess development tools.

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Processes with stem cells, microbes and enzymes are viable in microfluidic devices.

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Microfluidic devices with integrated sensors provide high quality data.

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Laminar flow enables spatial and temporal control over transport phenomena.

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Standardization of devices required for automation and industrial uptake.

Scale-down approaches have long been applied in bioprocessing to resolve scale-up problems. Miniaturized bioreactors have thrived as a tool to obtain process relevant data during early-stage process development. Microfluidic devices are an attractive alternative in bioprocessing development due to the high degree of control over process variables afforded by the laminar flow, and the possibility to reduce time and cost factors. Data quality obtained with these devices is high when integrated with sensing technology and is invaluable for scale-translation and to assess the economical viability of bioprocesses. Microfluidic devices as upstream process development tools have been developed in the area of small molecules, therapeutic proteins, and cellular therapies. More recently, they have also been applied to mimic downstream unit operations.