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Biotechnology and Bioengineering | Page 2

Yun Bai, Murray Moo-Young, William A Anderson
Rocking disposable bioreactors are a newer approach to smaller-scale cell growth that use a cyclic rocking motion to induce mixing and oxygen transfer from the headspace gas into the liquid. Compared to traditional stirred-tank and pneumatic bioreactors, rocking bioreactors operate in a very different physical mode and in this work the oxygen transfer pathways are re-assessed to develop a fundamental mass transfer (kL a) model that is compared to experimental data. The model combines two mechanisms, namely surface aeration and oxygenation via a breaking wave with air entrainment, borrowing concepts from ocean wave models...
April 30, 2019: Biotechnology and Bioengineering
J Carl Schultz, Mingfeng Cao, Huimin Zhao
The oleaginous yeast Rhodosporidium toruloides is considered a promising candidate for production of chemicals and biofuels thanks to its ability to grow on lignocellulosic biomass, and its high production of lipids and carotenoids. However, efforts to engineer this organism are hindered by a lack of suitable genetic tools. Here we report the development of a CRISPR/Cas9 system for genome editing in R. toruloides based on a fusion 5S rRNA-tRNA promoter for gRNA expression, capable of greater than 95% gene knockout for various genetic targets...
April 30, 2019: Biotechnology and Bioengineering
Vanessa M Vasconcellos, Cristiane S Farinas, Eduardo Ximenes, Patricia Slininger, Michael Ladisch
Adaptive laboratory evolution through 12 rounds of culturing experiments of the nanocellulose producing bacterium Komagataeibacter hansenii ATCC 23769 in liquid fraction from hydrothermal pretreatment of corn stover resulted in a strain that resists inhibition by phenolics. The original strain generated nanocellulose from glucose in standard Hestrin and Schramm (HS) medium, but not from the glucose in pretreatment liquid. K. hansenii cultured in pretreatment liquid treated with activated charcoal to remove inhibitors also converted glucose to bacterial nanocellulose and used xylose as carbon source for growth...
April 30, 2019: Biotechnology and Bioengineering
Gavin Kurgan, Christian Sievert, Andrew Flores, Aidan Schneider, Thomas Billings, Larry Panyon, Chandler Morris, Eric Taylor, Logan Kurgan, Reed Cartwright, Xuan Wang
Efficient xylose utilization will facilitate microbial conversion of lignocellulosic sugar mixtures into valuable products. In Escherichia coli, xylose catabolism is controlled by carbon catabolite repression. However, in E. coli such as the succinate-producing strain KJ122 with disrupted carbon catabolite repression, xylose utilization is still inhibited under fermentative conditions. To probe the underlying genetic mechanisms inhibiting xylose utilization, we evolved KJ122 to enhance its xylose fermentation abilities in parallel and characterized the potential convergent genetic changes shared by multiple independently evolved strains...
April 30, 2019: Biotechnology and Bioengineering
Moritz K F Wolf, Andrea Müller, Jonathan Souquet, Hervé Broly, Massimo Morbidelli
The development of mammalian cell perfusion cultures is still laborious and complex to perform due to the limited availability of scale-down models and limited knowledge on time- and cost-effective procedures. The maximum achievable viable cell density (VCDmax ), minimum cell specific perfusion rate (CSPRmin ), cellular growth characteristics and resulting bleed rate at steady-state operation are key variables for the effective development of perfusion cultures. In this work, we developed a stepwise procedure to use shake-tube (ST) in combination with benchtop (BR) bioreactors for the design of a mammalian cell perfusion culture at high productivity (23 pg/cell/day) and low product loss in the bleed (around 10%) for a given expression system...
April 30, 2019: Biotechnology and Bioengineering
Jeanette M Caronia, Daniel W Sorensen, Hope M Leslie, Jop H van Berlo, Samira M Azarin
Local delivery of viral vectors can enhance the efficacy of therapies by selectively affecting necessary tissues and reducing the required vector dose. Pluronic F127 is a thermosensitive polymer that undergoes a solution-gelation (sol-gel) transition as temperature increases and can deliver vectors without damaging them. While pluronics can be spread over large areas, such as the surface of an organ, prior to gelation, they lack sufficient adhesivity to remain attached to some tissues, such as the surface of the heart or mucosal surfaces...
April 30, 2019: Biotechnology and Bioengineering
Romina Lasry Testa, Claudio Delpino, Vanina Estrada, M Soledad Diaz
Cyanobacteria have been considered as promising candidates for sustainable bioproduction from inexpensive raw materials, as they grow on light, carbon dioxide and minimal inorganic nutrients. In this work, we present a genome-scale metabolic network model for Synechocystis sp. PCC 6803 and study the optimal design of the strain for ethanol production by using a Mixed Integer Linear Problem (MILP) reformulation of a bilevel programming problem that identifies gene knock-outs which lead to coupling between growth and product synthesis...
April 29, 2019: Biotechnology and Bioengineering
Vania Bertrand, Daniel J Karst, Alessia Bachmann, Katia Cantalupo, Miroslav Soos, Massimo Morbidelli
Long-term continuous protein production can be reached by perfusion operation. Through the continuous removal of waste metabolites and supply of nutrients, steady-state (SS) conditions are achieved after a certain transient period, where the conditions inside the reactor are not only uniform in space but also constant in time. Such stable conditions may have beneficial influences on the reduction of product heterogeneities. In this study, we investigated the impact of a perfusion cultivation on the intracellular physiological state of a CHO cell line producing a monoclonal antibody (mAb) by global transcriptomics and proteomics...
April 18, 2019: Biotechnology and Bioengineering
Leizhen Zhao, Bin Ye, Qi Zhang, Dan Cheng, Chaoyang Zhou, Shan Cheng, Xin Yan
Although one of the major factors limiting the application of Bacillus subtilis as an expression host has been its production of at least eight extracellular proteases, researchers have also noticed that some proteases benefited the secretion of foreign proteins at times. Therefore, to maximize the yield of a foreign protein, the proteases should be selectively inactivated. This raises a new question that how to identify the favorable and unfavorable proteases for a target protein. Here, an evaluation system containing nine mutant strains of B...
April 16, 2019: Biotechnology and Bioengineering
Jie Dong, Yan Chen, Veronica Teixeira Benites, Edward E K Baidoo, Christopher J Petzold, Harry R Beller, Aymerick Eudes, Henrik V Scheller, Paul D Adams, Aindrila Mukhopadhyay, Blake A Simmons, Steven W Singer
Plants are an attractive source of renewable carbon for conversion to biofuels and bio-based chemicals. Conversion strategies often use a fraction of the biomass, focusing on sugars from cellulose and hemicellulose. Strategies that use plant components such as aromatics and amino acids may improve the efficiency of biomass conversion. Pseudomonas putida is a promising host for its ability to metabolize a wide variety of organic compounds. P. putida was engineered to produce methyl ketones, which are promising diesel blendstocks and potential platform chemicals, from glucose and lignin-related aromatics...
April 14, 2019: Biotechnology and Bioengineering
Samuel D Stimple, Sibel Kalyoncu, Alec A Desai, Jesper E Mogensen, Lotte T Spang, Désirée J Asgreen, Arne Staby, Peter M Tessier
Sensitive detection of protein aggregates is important for evaluating the quality of biopharmaceuticals and detecting misfolded proteins in several neurodegenerative diseases. However, it is challenging to detect extremely low concentrations (<10 ppm) of aggregated protein in the presence of high concentrations of natively-folded (soluble) protein. Glucagon, a peptide hormone used in the treatment of extreme hypoglycemia, is aggregation-prone and forms amyloid fibrils. Detection of glucagon fibrils using conformation-specific antibodies is an attractive approach for identifying such aggregates during process and formulation development...
April 14, 2019: Biotechnology and Bioengineering
Christopher T Straub, Piyum A Khatibi, Jonathan K Otten, Michael W W Adams, Robert M Kelly
The extreme thermophile Caldicellulosiruptor bescii solubilizes and metabolizes the carbohydrate content of lignocellulose, a process that ultimately ceases because of biomass recalcitrance, accumulation of fermentation products, inhibition by lignin moieties, and reduction of metabolic activity. Deconstruction of low loadings of lignocellulose (5 g/l), either natural or transgenic, whether unpretreated or subjected to hydrothermal processing, by C. bescii typically results in less than 40% carbohydrate solubilization...
April 14, 2019: Biotechnology and Bioengineering
Hadi Nazem-Bokaee, Dayue Chen, Sean Michael O'Donnell, Andrew L Zydney
Virus filtration remains a critical step in the downstream process for the production of monoclonal antibodies and other mammalian cell-derived biotherapeutics. Recent studies have shown large differences in virus capture behavior of different virus filters, although the origin of these differences is still unclear. The objective of this study was to use confocal and scanning electron microscopy to directly evaluate the capture of virus-size nanoparticles in Planova 20N and BioEX hollow fiber virus filters...
April 14, 2019: Biotechnology and Bioengineering
Lina Apitius, Kristin Rübsam, Christina Jakesch, Felix Jakob, Ulrich Schwaneberg
Accumulation of plastics in the environment became a geological indicator of the Anthropocene era. An effective reduction of long-lasting plastics requires a treatment with microorganisms that release polymer-degrading enzymes. Polymer binding peptides function as adhesion promoters and enable a targeted binding of whole cells to polymer surfaces. An esterase A-based E. coli cell surface display screening system was developed, that enabled directed evolution of polymer binding peptides for improved binding strength to polymers...
April 14, 2019: Biotechnology and Bioengineering
Ghislaine Béhar, Axelle Renodon-Cornière, Stanimir Kambarev, Petar Vukojicic, Nathalie Caroff, Stéphane Corvec, Barbara Mouratou, Frédéric Pecorari
Detection and capture methods using antibodies have been developed to ensure identification of pathogens in biological samples. Though antibodies have many attractive properties, they also have limitations and there are needs to expand the panel of available affinity proteins with different properties. Affitins, that we developed from the Sul7d proteins, are a solid class of affinity proteins which can be used as substitutes to antibodies or to complement them. We report the generation and characterization of anti-bacterial Affitins with high specificity for Staphylococcus aureus...
April 14, 2019: Biotechnology and Bioengineering
Salvatore Petralia, Daniele Motta, Sabrina Conoci
In this paper, a miniaturized biosensor containing 96 silicon micro-chambers electro-loaded with nano-volumes of liquid (EW-Chip) is presented. The liquid electro-loading is achieved by the appropriate modulation of interface properties. The surface chemistries have been studied to guarantee effective interface properties for both ElectroWetting on Dielectric (EWoD) actuaction and biocompatibility versus biochemical reactions. The silicon micro-chambers are 200 nl in volume and are connected to a specific system of electrodes able to deliver liquid sample on each wells...
April 9, 2019: Biotechnology and Bioengineering
Shyam Sundhar Bale, Andrea Manoppo, Rebecca Thompson, Alex Markoski, Jonathan Coppeta, Hesham Azizgolshani, Mingjian Lu, James Gosset, Philip Keegan, Joe Charest
Hepatic in vitro platforms ranging from multi-well cultures to bioreactors and microscale systems have been developed as tools to recapitulate cellular function and responses to aid in drug screening and disease model development. Recent developments in microfabrication techniques and cellular materials enabled fabrication of next-generation, advanced microphysiological systems (MPSs) that aim to capture the cellular complexity and dynamic nature of the organ presenting highly controlled extracellular cues to cells in a physiologically relevant context...
April 9, 2019: Biotechnology and Bioengineering
Nico Betterle, Anastasios Melis
The work aims to convert the secondary slow metabolism of the terpenoid biosynthetic pathway into a primary activity in cyanobacteria, and to generate heterologous products using these photosynthetic microorganisms as cell factories. Case study is the production of the 10-carbon monoterpene β-phellandrene (PHL) in Synechocystis sp. PCC 6803 (Synechocystis). Barriers to this objective include the slow catalytic activity of the terpenoid metabolism enzymes that limits rates and yield of product synthesis and accumulation...
April 9, 2019: Biotechnology and Bioengineering
Matthew Gagnon, Shashikant Nagre, Wenge Wang, Jon Coffman, Gregory W Hiller
A novel, alternative intensified cell culture process comprised of a linked bioreactor system is presented. An N-1 perfusion bioreactor maintained cells in a highly proliferative state and provided a continuous inoculum source to a second bioreactor operating as a continuous-flow stirred-tank reactor (CSTR). An initial study evaluated multiple system steady-states by varying N-1 steady-state viable cell densities, N-1 to CSTR working volume ratios, and CSTR dilution rates. After identifying near optimum system steady-state parameters yielding a relatively high volumetric productivity while efficiently consuming media, a subsequent lab scale experiment demonstrated the start-up and long-term operation of the envisioned manufacturing process for 83 days...
April 5, 2019: Biotechnology and Bioengineering
Chae Rin Park, Won Jong Rhee, Kyu Won Kim, Byeong Hee Hwang
On-site genetic detection needs to develop a sensitive and straightforward biosensor without special equipment which can detect various genetic biomarkers. Hybridization chain reaction amplifying signal isothermally could be considered as a good candidate for on-site detection. Here, we developed a novel genetic biosensor based on enzyme-free dual-amplification of universal hybridization chain reaction (uHCR) and hemin/G-quadruplex horseradish peroxidase (HRP)-mimicking DNAzyme. The uHCR is the strategy which enables simple design for multiple target detection by the introduction of target-specific trigger hairpin without changing the whole system according to a target change...
April 1, 2019: Biotechnology and Bioengineering
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