Publications by authors named "Leandro Buchmann"

7 Publications

  • Page 1 of 1

Automated Online Flow Cytometry Advances Microalgal Ecosystem Management as , High-Temporal Resolution Monitoring Tool.

Front Bioeng Biotechnol 2021 23;9:642671. Epub 2021 Mar 23.

Sustainable Food Processing Laboratory, Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland.

Microalgae are emerging as a next-generation biotechnological production system in the pharmaceutical, biofuel, and food domain. The economization of microalgal biorefineries remains a main target, where culture contamination and prokaryotic upsurge are main bottlenecks to impair culture stability, reproducibility, and consequently productivity. Automated online flow cytometry (FCM) is gaining momentum as bioprocess optimization tool, as it allows for spatial and temporal landscaping, real-time investigations of rapid microbial processes, and the assessment of intrinsic cell features. So far, automated online FCM has not been applied to microalgal ecosystems but poses a powerful technology for improving the feasibility of microalgal feedstock production through , real-time, high-temporal resolution monitoring. The study lays the foundations for an application of automated online FCM implying far-reaching applications to impel and facilitate the implementation of innovations targeting at microalgal bioprocesses optimization. It shows that emissions collected on the FL1/FL3 fluorescent channels, harnessing nucleic acid staining and chlorophyll autofluorescence, enable a simultaneous assessment (quantitative and diversity-related) of prokaryotes and industrially relevant phototrophic in mixed ecosystems of different complexity over a broad concentration range (2.2-1,002.4 cells ⋅μL). Automated online FCM combined with data analysis relying on phenotypic fingerprinting poses a powerful tool for quantitative and diversity-related population dynamics monitoring. Quantitative data assessment showed that prokaryotic growth phases in engineered and natural ecosystems were characterized by different growth speeds and distinct peaks. Diversity-related population monitoring based on phenotypic fingerprinting indicated that prokaryotic upsurge in mixed cultures was governed by the dominance of single prokaryotic species. Automated online FCM is a powerful tool for microalgal bioprocess optimization owing to its adaptability to myriad phenotypic assays and its compatibility with various cultivation systems. This allows advancing bioprocesses associated with both microalgal biomass and compound production. Hence, automated online FCM poses a viable tool with applications across multiple domains within the biobased sector relying on single cell-based value chains.
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http://dx.doi.org/10.3389/fbioe.2021.642671DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8023406PMC
March 2021

Nanosecond pulsed electric field processing of microalgae based biorefineries governs growth promotion or selective inactivation based on underlying microbial ecosystems.

Bioresour Technol 2021 Jan 24;319:124173. Epub 2020 Sep 24.

Swiss Federal Institute of Technology (ETH), Zurich, Institute of Food, Nutrition and Health, Sustainable Food Processing Laboratory, Schmelzbergstrasse 9, Zurich 8092, Switzerland. Electronic address:

Nanosecond pulsed electric field treatment (nsPEF) is a technology-driven, resource-efficient approach fostering microalgae biorefineries for transforming them into economically viable scenarios. A processing window of 100 ns, 7 Hz, and 10 kV cm significantly leveraged phototrophic Chlorella vulgaris and bacterial counts up to + 50.1 ± 12.2% and + 77.0 ± 37.4%, respectively (n = 4; p < 0.05) in non-axenic cultures. Applying the same processing window decreased C. vulgaris (-17.1 ± 13.8%) and prokaryotic (-82.7 ± 14.6%) counts owing to alterations in the prokaryotic community diversity. Principle coordinate analysis of prokaryotic phenotypic fingerprints indicated that phenotype or metabolism related diversity changes in the prokaryotic community affected the treatment outcome. The study fosters the upsurge of industrial-scale nsPEF realization and the economic viability of microalgae biorefineries through improved process understanding and thus control. It perpetuates nsPEF applicability for microalgae feedstock production and several other applications within single-cell biorefineries in the bio-based domain.
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http://dx.doi.org/10.1016/j.biortech.2020.124173DOI Listing
January 2021

Perspective on Pulsed Electric Field Treatment in the Bio-based Industry.

Front Bioeng Biotechnol 2019 16;7:265. Epub 2019 Oct 16.

Laboratory of Sustainable Food Processing, Department of Health Sciences and Technology, Institute of Food Nutrition and Health, IFNH, ETH Zurich, Zurich, Switzerland.

The bio-based industry is urged to find solutions to meet the demands of a growing world population. In this context, increased resource efficiency is a major goal. Pulsed electric field (PEF) processing is a promising technological solution. Conventional PEF and the emerging area of nanosecond PEF (nsPEF) have been shown to induce various biological effects, with nsPEF inducing pronounced intracellular effects, which could provide solutions for currently faced challenges. Based on the flexibility and continuous operation of PEF and nsPEF processing, the technology can be integrated into many existing cultivation systems; its modularity provides an approach for inducing specific effects. Depending on the treatment conditions, selective inactivation, continuous extraction without impeding cell viability, as well as the stimulation of cell growth and/or cellular compound stimulation are potential applications in the bio-based industry. However, continuous treatment currently involves heterogeneous energy inputs. Increasing the homogeneity of PEF and nsPEF processing by considering the flow and electric field heterogeneity may allow for more targeted effects on biological cells, further increasing the potential of the technology for bio-based applications. We provide an overview of existing and potential applications of PEF and nsPEF and suggest that theoretical and practical analyses of flow and electric field heterogeneity may provide a basis for obtaining more targeted effects on biological cells and for further increasing the bio-based applications of the technology, which thereby could become a key technology for circular economy approaches in the future.
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http://dx.doi.org/10.3389/fbioe.2019.00265DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6805697PMC
October 2019

Continuous nanosecond pulsed electric field treatments foster the upstream performance of Chlorella vulgaris-based biorefinery concepts.

Bioresour Technol 2019 Dec 19;293:122029. Epub 2019 Aug 19.

ETH Zurich, Department of Health Sciences and Technology, Institute of Food, Nutrition and Health, Sustainable Food Processing Laboratory, Schmelzbergstrasse 9, Zurich 8092, Switzerland. Electronic address:

Nanosecond pulsed electric field treatment (nsPEF) is an innovative, technology-driven, and resource-efficient approach to foster the upstream performance of microalgae-based biorefinery concepts to transform microalgae into economic more viable raw materials for the biobased industry. A processing window applying three treatments of 100 ns, 5 Hz, and 10 kV cm to industrially relevant phototrophic Chlorella vulgaris in the early exponential growth phase significantly increased biomass yields by up to 17.53 ± 10.46% (p = 3.18 × 10). Treatments had limited effects on the carbon and pigment contents, but the protein content was decreased. The longest possible pulse width (100 ns) resulted in the highest biomass yield indicating underlying working mechanisms of enhanced cell proliferation based on intracellular and plasma membrane-related effects. The applicability to eukaryotes and prokaryotes, such as C. vulgaris and cyanobacteria highlights the possible impacts of nsPEF across multiple domains of the biobased industry relying on single-cell-based value-chains.
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http://dx.doi.org/10.1016/j.biortech.2019.122029DOI Listing
December 2019

Pulsed electric field based cyclic protein extraction of microalgae towards closed-loop biorefinery concepts.

Bioresour Technol 2019 Nov 24;291:121870. Epub 2019 Jul 24.

ETH Zurich, Department of Health Sciences and Technology, Institute of Food Nutrition and Health, IFNH, Laboratory of Sustainable Food Processing, Schmelzbergstrasse 9, Zurich 8092, Switzerland. Electronic address:

Microalgae-based biorefinery concepts can contribute to providing sufficient resources for a growing world population. However, the performance needs to be improved, which requires innovative technologies and processes. Continuous extraction from Chlorella vulgaris cultures via pulsed electric field (PEF) processing might be a viable process to increase the performance of microalgae-based biorefinery concepts. In this study, increasing protein extraction rates were observed with increasing electric field strength, up to 96.6 ± 4.8% of the free protein in the microalgae. However, increased extraction rates negatively influenced microalgae growth after PEF treatment. A free protein extraction rate up to 29.1 ± 1.1% without a significant influence on microalgal growth after 168 h was achieved (p = 0.788). Within the scope of this work, a protocol for continuous protein extraction during microalgae cultivation by PEF processing was developed. The incorporation of innovative downstream into upstream processing could be a viable future concept.
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http://dx.doi.org/10.1016/j.biortech.2019.121870DOI Listing
November 2019

Effect of nanosecond pulsed electric field treatment on cell proliferation of microalgae.

Bioresour Technol 2019 Jan 26;271:402-408. Epub 2018 Sep 26.

ETH Zurich, Department of Health Sciences and Technology, Institute of Food, Nutrition and Health, IFNH, Sustainable Food Processing Laboratory, Schmelzbergstrasse 9, Zurich 8092, Switzerland. Electronic address:

Photoautotrophic microalgae based biorefinery concepts are currently not competitive compared to other established production systems. Therefore, innovative upstream processes need to be developed to increase the competitiveness of photoautotrophic microalgae biorefinery concepts. Abiotic sub-lethal stress induction via nanosecond pulsed electric field (nsPEF) treatment might be a viable process to increase the efficiency of photoautotrophic microalgae cultivation. In this work, an increased cell growth after nsPEF treatment was observable. Application of nsPEF to highly proliferating cells in a repetitive process resulted in a statistical significant increase in cell growth (p = 0.009). The effect was most pronounced after five days wherefore cellular structures and processes were analyzed to reveal a possible mechanism. Within this work, a protocol for increased cell proliferation with a possible mechanism was derived, which improves competitiveness of photoautotrophic microalgae biorefineries in the future. However, based on the derived mechanism, the results are also relevant for other microorganisms.
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http://dx.doi.org/10.1016/j.biortech.2018.09.124DOI Listing
January 2019

Comprehensive pulsed electric field (PEF) system analysis for microalgae processing.

Bioresour Technol 2018 Oct 7;265:268-274. Epub 2018 Jun 7.

ETH Zurich, Institute of Food Nutrition and Health, Laboratory of Sustainable Food Processing, Schmelzbergstrasse 9, Zurich 8092, Switzerland. Electronic address:

Pulsed electric field (PEF) is an emerging nonthermal technique with promising applications in microalgae biorefinery concepts. In this work, the flow field in continuous PEF processing and its influencing factors were analyzed and energy input distributions in PEF treatment chambers were investigated. The results were obtained using an interdisciplinary approach that combined multiphysics simulations with ultrasonic Doppler velocity profiling (UVP) and rheological measurements of Arthrospira platensis suspensions as a case study for applications in the biobased industry. UVP enabled non-invasive validation of multiphysics simulations. A. platensis suspensions follow a non-Newtonian, shear-thinning behavior, and measurement data could be fitted with rheological functions, which were used as an input for fluid dynamics simulations. Within the present work, a comprehensive system characterization was achieved that will facilitate research in the field of PEF processing.
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http://dx.doi.org/10.1016/j.biortech.2018.06.010DOI Listing
October 2018