Enhancing single-cell bioconversion efficiency by harnessing nanosecond pulsed electric field processing

Nanosecond pulsed electric field (nsPEF) processing is gaining momentum as a physical means for single-cell bioconversion efficiency enhancement. The technology allows biomass yields per substrate (YX/S) to be leveraged and poses a viable option for stimulating intracellular compound production. NsPEF processing thus resonates with myriad domains spanning the pharmaceutical and medical sectors, as well as food and feed production. The exact working mechanisms underlying nsPEF-based enhancement of bioconversion efficiency, however, remain elusive, and a better understanding would be pivotal for leveraging process control to broaden the application of nsPEF and scale-up industrial implementation. To bridge this gap, the study provides the electrotechnological and metabolic fundamentals of nsPEF processing in the bio-based domain to enable a critical evaluation of pathways underlying the enhancement of single-cell bioconversion efficiency. Evidence suggests that treating cells during the rapid proliferating and thus the early to mid-exponential state of cellular growth is critical to promoting bioconversion efficiency. A combined effect of transient intracellular and sublethal stress induction and effects caused on the plasma membrane level result in an enhancement of cellular bioconversion efficiency. Congruency exists regarding the involvement of transient cytosolic Ca2+ hubs in nsPEF treatment responses, as well as that of reactive oxygen species formation culminating in the onset of cellular response pathways. A distinct assignment of single effects and their contributions to enhancing bioconversion efficiency, however, remains challenging. Current applications of nsPEF processing comprise microalgae, bacteria, and yeast biorefineries, but these endeavors are in their infancies with limitations associated with a lack of understanding of the underlying treatment mechanisms, an incomplete reporting, insufficient characterization, and control of processing parameters. The study aids in fostering the upsurge of nsPEF applications in the bio-based domain by providing a basis to gain a better understanding of cellular mechanisms underlying an nsPEF-based enhancement of cellular bioconversion efficiency and suggests best practice guidelines for nsPEF documentation for improved knowledge transfer. Better understanding and reporting of processes parameters and consequently improved process control could foster industrial-scale nsPEF realization and ultimately aid in perpetuating nsPEF applicability within the bio-based domain

Chlorella vulgaris in a heterotrophic bioprocess : study of the lipid bioaccessibility and oxidative stability

Microalgal biomass is an emerging source of several health-related compounds, including polyunsaturated fatty acids. Herein, Chlorella vulgaris was cultivated heterotrophically in a 16-L stirred tank bioreactor. The lipid oxidative stability and lipid bioaccessibility of the biomass harvested during the exponential and stationary phases were evaluated. The biomass harvested during the stationary phase showed lower lipid oxidation than that harvested during the exponential phase, likely due to the higher content of antioxidants in the former. In both biomasses, the hexanal and propanal profiles showed only moderate increase over 12 weeks of storage at 40 °C, indicating good oxidative stability. Lipid bioaccessibility measured in an infant in vitro model was 0.66% ± 0.16% and 2.41% ± 0.61% for the biomass harvested during the exponential and late stationary phases, respectively. This study indicates that C. vulgaris biomass can be considered as a stable and nutritious (optimal ω3:ω6 profile) source of essential fatty acids. Our results suggested that regarding lipid stability and bioaccessibility, harvesting during stationary phase could be preferred choice. In general, treatment of the biomass to increase lipid bioaccessibility should be investigated

Digitalization in Processes: FH-HES Universities of Applied Sciences

Digitalization is having an increasing impact on all industrial sectors, including the chemical and biotechnological industries. Aiming for innovative research and development, the Swiss Universities of Applied Sciences play a pivotal role in transferring academic knowledge and know-how to industrial practice. We review selected examples of projects related to the digitalization of processes and bioprocesses at four different institutions across Switzerland. These developments cover the whole spectrum of digital technologies, including big data, connectivity, analytics and automation. They are conducted in close collaboration with industrial partners and aim to support the growth of this important industrial sector

Productivity, amino acid profile, and protein bioaccessibility in heterotrophic batch cultivation of Galdieria sulphuraria

The polyextremophilic Galdieria sulphuraria is emerging as a promising microalgal species for food applications. This work explores the potential of heterotrophically cultivated G. sulphuraria as a protein producer for human consumption. To this end, the performances of four G. sulphuraria strains grown under the same conditions were compared. Amino acid profiles varied among strains and growth phases, but all samples met FAO dietary requirements for adults. The specific growth rates were between 1.01 and 1.48 day−1. After glucose depletion, all strains showed an increase of 38–49 % in nitrogen content within 48 h, reaching 7.8–12.0 % w/w. An opposite trend was observed in protein bioaccessibility, which decreased on average from 69 % during the exponential phase to a minimum of 32 % 48 h after stationary phase, with significant differences among the strains. Therefore, selecting the appropriate strain and harvesting time is crucial for successful single-cell protein production.ISSN:1873-2976ISSN:0960-852

Bioprocess monitoring: minimizing sample matrix effects for total protein quantification with bicinchoninic acid assay

Determining total protein content is a routine operation in many laboratories. Despite substantial work on assay optimization interferences, the widely used bicinchoninic acid (BCA) assay remains widely recognized for its robustness. Especially in the field of bioprocess engineering the inaccuracy caused by interfering substances remains hardly predictable and not well understood. Since the introduction of the assay, sample pre-treatment by trichloroacetic acid (TCA) precipitation has been indicated as necessary and sufficient to minimize interferences. However, the sample matrix in cultivation media is not only highly complex but also dynamically changing over process time in terms of qualitative and quantitative composition. A significant misestimation of the total protein concentration of bioprocess samples is often observed when following standard work-up schemes such as TCA precipitation, indicating that this step alone is not an adequate means to avoid measurement bias. Here, we propose a modification of the BCA assay, which is less influenced by sample complexity. The dynamically changing sample matrix composition of bioprocessing samples impairs the conventional approach of compensating for interfering substances via a static offset. Hence, we evaluated the use of a correction factor based on an internal spike measurement for the respective samples. Using protein spikes, the accuracy of the BCA protein quantification could be improved fivefold, taking the BCA protein quantification to a level of accuracy comparable to other, more expensive methods. This will allow reducing expensive iterations in bioprocess development to due inaccurate total protein analytics

Charakterisierung und Optimierung eines Laborbioreaktors durch numerische Strömungsmechanik und Rapid Prototyping von Rührwerken

Am Beispiel des Minifors 2 wird die Entwicklung und Optimierung eines Benchtop Reaktors für mikrobielle Anwendungen dargestellt. Zunächst wurde der Reaktor verfahrenstechnisch charakterisiert, indem experimentell die Mischzeit, die Sauerstofftransferrate und der Leistungseintrag bestimmt sowie Kennwerte wie die Bewehrungszahl berechnet wurden. Zur Optimierung wurden mittels computer aided design (CAD) alternative Rührer und Einbauten wie Strombrecher erstellt und durch computational fluid dynamics (CFD) Simulationen geprüft und bewertet. Erfolgsversprechende Anpassungen wurden anschließend durch 3D-Druck hergestellt. Für die biologische Charakterisierung wurde der Reaktor in mikrobiellen Hochzelldichte-Prozessen schrittweise an die physiologischen Systemgrenzen (Sauerstoffbedarf, Wärmeableitung u.a.) herangeführt. Auf Basis der verfahrenstechnischen Charakterisierung wurden optimierte Bereiche für Begasungsraten und Rührerdrehzahlen definiert, und die Eignung des Systems für Batch, Fedbatch und kontinuierliche Verfahren evaluiert. Durch den kombinierten Einsatz von klassischen verfahrenstechnischen Methoden mit modernen Verfahren wie CFD und 3D-Druck wurde die Optimierung des Reaktors schneller und effizienter realisiert. In der biologischen Charakterisierung konnte die Gültigkeit der verfahrenstechnisch und modellbasiert ermittelten Kennwerte und Grenzen bestätigt werden

Digitalization in processes

Digitalization is having an increasing impact on all industrial sectors, including the chemical and biotechnological industries. Aiming for innovative research and development, the Swiss Universities of Applied Sciences play a pivotal role in transferring academic knowledge and know-how to industrial practice. We review selected examples of projects related to the digitalization of processes and bioprocesses at four different institutions across Switzerland. These developments cover the whole spectrum of digital technologies, including big data, connectivity, analytics and automation. They are conducted in close collaboration with industrial partners and aim to support the growth of this important industrial sector

Charakterisierung und Optimierung eines Laborbioreaktors durch numerische Strömungsmechanik und Rapid Prototyping von Rührwerken

Am Beispiel des Minifors 2 wird die Entwicklung und Optimierung eines Benchtop Reaktors für mikrobielle Anwendungen dargestellt. Zunächst wurde der Reaktor verfahrenstechnisch charakterisiert, indem experimentell die Mischzeit, die Sauerstofftransferrate und der Leistungseintrag bestimmt sowie Kennwerte wie die Bewehrungszahl berechnet wurden. Zur Optimierung wurden mittels computer aided design (CAD) alternative Rührer und Einbauten wie Strombrecher erstellt und durch computational fluid dynamics (CFD) Simulationen geprüft und bewertet. Erfolgsversprechende Anpassungen wurden anschließend durch 3D-Druck hergestellt. Für die biologische Charakterisierung wurde der Reaktor in mikrobiellen Hochzelldichte-Prozessen schrittweise an die physiologischen Systemgrenzen (Sauerstoffbedarf, Wärmeableitung u.a.) herangeführt. Auf Basis der verfahrenstechnischen Charakterisierung wurden optimierte Bereiche für Begasungsraten und Rührerdrehzahlen definiert, und die Eignung des Systems für Batch, Fedbatch und kontinuierliche Verfahren evaluiert. Durch den kombinierten Einsatz von klassischen verfahrenstechnischen Methoden mit modernen Verfahren wie CFD und 3D-Druck wurde die Optimierung des Reaktors schneller und effizienter realisiert. In der biologischen Charakterisierung konnte die Gültigkeit der verfahrenstechnisch und modellbasiert ermittelten Kennwerte und Grenzen bestätigt werden

Enhancing single-cell bioconversion efficiency by harnessing nanosecond pulsed electric field processing

Nanosecond pulsed electric field (nsPEF) processing is gaining momentum as a physical means for single-cell bioconversion efficiency enhancement. The technology allows biomass yields per substrate (YX/S) to be leveraged and poses a viable option for stimulating intracellular compound production. NsPEF processing thus resonates with myriad domains spanning the pharmaceutical and medical sectors, as well as food and feed production. The exact working mechanisms underlying nsPEF-based enhancement of bioconversion efficiency, however, remain elusive, and a better understanding would be pivotal for leveraging process control to broaden the application of nsPEF and scale-up industrial implementation. To bridge this gap, the study provides the electrotechnological and metabolic fundamentals of nsPEF processing in the bio-based domain to enable a critical evaluation of pathways underlying the enhancement of single-cell bioconversion efficiency. Evidence suggests that treating cells during the rapid proliferating and thus the early to mid-exponential state of cellular growth is critical to promoting bioconversion efficiency. A combined effect of transient intracellular and sublethal stress induction and effects caused on the plasma membrane level result in an enhancement of cellular bioconversion efficiency. Congruency exists regarding the involvement of transient cytosolic Ca2+ hubs in nsPEF treatment responses, as well as that of reactive oxygen species formation culminating in the onset of cellular response pathways. A distinct assignment of single effects and their contributions to enhancing bioconversion efficiency, however, remains challenging. Current applications of nsPEF processing comprise microalgae, bacteria, and yeast biorefineries, but these endeavors are in their infancies with limitations associated with a lack of understanding of the underlying treatment mechanisms, an incomplete reporting, insufficient characterization, and control of processing parameters. The study aids in fostering the upsurge of nsPEF applications in the bio-based domain by providing a basis to gain a better understanding of cellular mechanisms underlying an nsPEF-based enhancement of cellular bioconversion efficiency and suggests best practice guidelines for nsPEF documentation for improved knowledge transfer. Better understanding and reporting of processes parameters and consequently improved process control could foster industrial-scale nsPEF realization and ultimately aid in perpetuating nsPEF applicability within the bio-based domain.ISSN:0734-9750ISSN:1873-189