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    Formic acid as a secondary substrate for succinic acid production by metabolically engineered Mannheimia succiniciproducens.
    Biotechnol Bioeng 2017 Sep 19. Epub 2017 Sep 19.
    Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Plus program), BioProcess Engineering Research Center, Institute for the BioCentury, Yuseong-gu, Daejeon, Republic of Korea.
    There has been much effort exerted to reduce one carbon (C1) gas emission to address climate change. As one promising way to more conveniently utilize C1 gas, several technologies have been developed to convert C1 gas into useful chemicals such as formic acid (FA). In this study, systems metabolic engineering was utilized to engineer Mannheimia succiniciproducens to efficiently utilize FA. Read More

    Combinatorial genome and protein engineering yields monoclonal antibodies with hypergalactosylation from CHO cells.
    Biotechnol Bioeng 2017 Jul 7. Epub 2017 Jul 7.
    Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland.
    One of the key quality attributes of monoclonal antibodies is the glycan pattern and distribution. Two terminal galactose residues typically represent a small fraction of the total glycans from antibodies. However, antibodies with defined glycosylation properties including enhanced galactosylation have been shown to exhibit altered properties for these important biomedical modalities. Read More

    One pot synthesis of GDP-mannose by a multi-enzyme cascade for enzymatic assembly of lipid-linked oligosaccharides.
    Biotechnol Bioeng 2017 Sep 18. Epub 2017 Sep 18.
    Max Planck Institute for Dynamics of Complex Technical Systems, Bioprocess Engineering, Sandtorstr. 1, 39106 Magdeburg, Germany.
    Glycosylation of proteins is a key function of the biosynthetic-secretory pathway in the endoplasmic reticulum (ER) and Golgi apparatus. Glycosylated proteins play a crucial role in cell trafficking and signaling, cell-cell adhesion, blood-group antigenicity, and immune response. In addition, the glycosylation of proteins is an important parameter in the optimization of many glycoprotein-based drugs such as monoclonal antibodies. Read More

    Improved performance of Pseudomonas putida in a bioelectrochemical system through overexpression of periplasmic glucose dehydrogenase.
    Biotechnol Bioeng 2017 Sep 18. Epub 2017 Sep 18.
    Centre for Microbial Electrochemical Systems (CEMES), The University of Queensland, St Lucia 4072, Brisbane, Australia.
    It was recently demonstrated that a bioelectrochemical system (BES) with a redox mediator allowed Pseudomonas putida to perform anoxic metabolism, converting sugar to sugar acids with high yield. However, the low productivity currently limits the application of this technology. To improve productivity the strain was optimized through improved expression of glucose dehydrogenase (GCD) and gluconate dehydrogenase (GAD). Read More

    ΔFlucs: Brighter Photinus pyralis firefly luciferases identified by surveying consecutive single amino acid deletion mutations in a thermostable variant.
    Biotechnol Bioeng 2017 Sep 16. Epub 2017 Sep 16.
    School of Biosciences, University of Cardiff, Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX, UK.
    The bright bioluminescence catalysed by Photinus pyralis firefly luciferase (Fluc) enables a vast array of life science research such as bioimaging in live animals and sensitive in vitro diagnostics. The effectiveness of such applications is improved using engineered enzymes that to date have been constructed using amino acid substitutions. We describe ΔFlucs: consecutive single amino acid deletion mutants within 6 loop structures of the bright and thermostable x11 Fluc. Read More

    Imaging stem cell distribution, growth, migration, and differentiation in 3-D scaffolds for bone tissue engineering using mesoscopic fluorescence tomography.
    Biotechnol Bioeng 2017 Sep 16. Epub 2017 Sep 16.
    University of Maryland, Fischell Department of Bioengineering, 2218 Jeong H. Kim Engineering Building, College Park, Maryland 20742, USA.
    Regenerative medicine has emerged as an important discipline that aims to repair injury or replace damaged tissues or organs by introducing living cells or functioning tissues. Successful regenerative medicine strategies will likely depend upon a simultaneous optimization strategy for the design of biomaterials, cell-seeding methods, cell-biomaterial interactions and molecular signaling within the engineered tissues. It remains a challenge to image three-dimensional (3-D) structures and functions of the cell-seeded scaffold in mesoscopic scale (>2∼3 mm). Read More

    Exploring cellular behaviour under transient gene expression and its impact on mAb productivity and Fc-glycosylation.
    Biotechnol Bioeng 2017 Sep 16. Epub 2017 Sep 16.
    Centre for Process Systems Engineering, Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK.
    Transient gene expression (TGE) is a methodology employed in bioprocessing for the fast provision of recombinant protein material. Mild hypothermia is often introduced to overcome the low yield typically achieved with TGE and improve specific protein productivity. It is therefore of interest to examine the impact of mild hypothermic temperatures on both the yield and quality of transiently-expressed proteins and the relationship to changes in cellular processes and metabolism. Read More

    Karyotype variation of CHO host cell lines over time in culture characterized by chromosome counting and chromosome painting.
    Biotechnol Bioeng 2017 Sep 16. Epub 2017 Sep 16.
    Austrian Centre of Industrial Biotechnology, Graz, Austria.
    Genomic rearrangements are a common phenomenon in rapidly growing cell lines such as Chinese hamster ovary (CHO) cells, a feature that in the context of production of biologics may lead to cell line and product instability. Few methods exist to assess such genome wide instability. Here we use the population distribution of chromosome numbers per cell as well as chromosome painting to quantify the karyotypic variation in several CHO host cell lines. Read More

    Development of a Formaldehyde Biosensor with Application to Synthetic Methylotrophy.
    Biotechnol Bioeng 2017 Sep 16. Epub 2017 Sep 16.
    Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames Street, MIT 56-469C Cambridge, Massachusetts 02139.
    Formaldehyde is a prevalent environmental toxin and a key intermediate in single carbon metabolism. The ability to monitor formaldehyde concentration is therefore of interest for both environmental monitoring and for metabolic engineering of native and synthetic methylotrophs, but current methods suffer from low sensitivity, complex workflows, or require expensive analytical equipment. Here we develop a formaldehyde biosensor based on the FrmR repressor protein and cognate promoter of E. Read More

    Recoding of synonymous genes to expand evolutionary landscapes requires control of secondary structure affecting translation.
    Biotechnol Bioeng 2017 Sep 12. Epub 2017 Sep 12.
    Institut Pasteur, Unité de Plasticité du Génome Bactérien, Département Génomes et Génétique, Paris, France.
    Synthetic DNA design needs to harness the many information layers embedded in a DNA string. We previously developed the Evolutionary Landscape Painter (ELP), an algorithm that exploits the degeneracy of the code to increase protein evolvability. Here, we have used ELP to recode the integron integrase gene (intI1) in two alternative alleles. Read More

    Inhibition analysis of inhibitors derived from lignocellulose pretreatment on the metabolic activity of Zymomonas mobilis biofilm and planktonic cells and the proteomic responses.
    Biotechnol Bioeng 2017 Sep 11. Epub 2017 Sep 11.
    National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathumthani, 12120, Thailand.
    Lignocellulose pretreatment produces various toxic inhibitors that affect microbial growth, metabolism and fermentation. Zymomonas mobilis is an ethanologenic microbe that has been demonstrated to have potential to be used in lignocellulose biorefineries for bioethanol production. Z. Read More

    Systematic Optimization of L-Tryptophan Riboswitches for Efficient Monitoring of the Metabolite in Escherichia coli.
    Biotechnol Bioeng 2017 Sep 11. Epub 2017 Sep 11.
    Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk, 37673, Korea.
    Riboswitches form a class of genetically-encoded sensor-regulators and are considered as promising tools for monitoring various metabolites. Functional parameters of a riboswitch, like dynamic or operational range, should be optimized before it is implemented in a specific application for monitoring the target molecule efficiently. However, optimization of a riboswitch was not straightforward and required detailed studies owing to its complex sequence-function relationship. Read More

    Fabricating PLGA microparticles with high loads of the small molecule antioxidant N-acetylcysteine that rescue oligodendrocyte progenitor cells from oxidative stress.
    Biotechnol Bioeng 2017 Sep 5. Epub 2017 Sep 5.
    University of Virginia, Charlottesville, VA, Department of Chemical Engineering.
    Reactive oxygen species (ROS), encompassing all oxygen radical or non-radical oxidizing agents, play key roles in disease progression. Controlled delivery of antioxidants is therapeutically relevant in such oxidant-stressed environments. Encapsulating small hydrophilic molecules into hydrophobic polymer microparticles via traditional emulsion methods has long been a challenge due to rapid mass transport of small molecules out of particle pores. Read More

    Constructing arabinofuranosidases for dual arabinoxylan debranching activity.
    Biotechnol Bioeng 2017 Sep 4. Epub 2017 Sep 4.
    Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada.
    Enzymatic conversion of arabinoxylan requires α-L-arabinofuranosidases able to remove α-L-arabinofuranosyl residues (α-L-Araf) from both mono- and double-substituted D-xylopyranosyl residues (Xylp) in xylan (i.e., AXH-m and AXH-d activity). Read More

    Temperature-dependent dynamic control of the TCA cycle increases volumetric productivity of itaconic acid production by Escherichia coli.
    Biotechnol Bioeng 2017 Sep 2. Epub 2017 Sep 2.
    Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106 Magdeburg, Germany.
    Based on the recently constructed E. coli itaconic acid production strain ita23, we aimed to improve the productivity by applying a two-stage process strategy with decoupled production of biomass and itaconic acid. We constructed a strain ita32 (MG1655 ▵aceA ▵pta ▵pykF ▵pykA pCadCs), which, in contrast to ita23, has an active tricarboxylic acid (TCA) cycle and a fast growth rate of 0. Read More

    Countercurrent Staged Diafiltration for Formulation of High Value Proteins.
    Biotechnol Bioeng 2017 Sep 2. Epub 2017 Sep 2.
    Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802.
    A number of groups have studied the application of continuous bioreactors and continuous chromatographic systems as part of efforts to develop an integrated continuous biomanufacturing process. The objective of this study was to examine the feasibility of using a countercurrent staged diafiltration process for continuous protein formulation with reduced buffer requirements. Experiments were performed using a polyclonal immunoglobulin (IgG) with Cadence(TM) Inline Concentrators. Read More

    Dry biorefining maximizes the potentials of simultaneous saccharification and co-fermentation for cellulosic ethanol production.
    Biotechnol Bioeng 2017 Sep 2. Epub 2017 Sep 2.
    State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China.
    Despite the well-recognized merits of simultaneous saccharification and co-fermentation (SSCF) on relieving sugar product inhibition on cellulase activity, a practical concomitance difficulty of xylose with inhibitors in the pretreated lignocellulose feedstock prohibits the essential application of SSCF for cellulosic ethanol fermentation. To maximize the SSCF potentials for cellulosic ethanol production, a dry biorefining approach was proposed starting from dry acid pretreatment, disk milling and biodetoxification of lignocellulose feedstock. The successful SSCF of the inhibitor free and xylose conserved lignocellulose feedstock after dry biorefining reached a record high ethanol titer at moderate cellulase usage and minimum wastewater generation. Read More

    Glucose-stimulated insulin release: Parallel perifusion studies of free and hydrogel encapsulated human pancreatic islets.
    Biotechnol Bioeng 2017 Sep 2. Epub 2017 Sep 2.
    Department of Biomedical Engineering, University of Florida, Gainesville, Florida.
    To explore the effects immune-isolating encapsulation has on the insulin secretion of pancreatic islets and to improve our ability to quantitatively describe the glucose-stimulated insulin release (GSIR) of pancreatic islets, we conducted dynamic perifusion experiments with isolated human islets. Free (unencapsulated) and hydrogel encapsulated islets were perifused, in parallel, using an automated multi-channel system that allows sample collection with high temporal resolution. Results indicated that free human islets secrete less insulin per unit mass or islet equivalent (IEQ) than murine islets and with a less pronounced first-phase peak. Read More

    Development of a general defined medium for Pichia pastoris.
    Biotechnol Bioeng 2017 Sep 2. Epub 2017 Sep 2.
    Department of Chemical Engineering, Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 500 Main Street, Cambridge MA 02139, USA.
    Pichia pastoris is widely used as a host for recombinant protein production. More than 500 proteins have been expressed in the organism at a variety of cultivation scales, from small shake flasks to large bioreactors. Large-scale fermentation strategies typically employ chemically-defined growth medium because of its greater batch-to-batch consistency and in many cases, lower costs compared to complex medium. Read More

    Power Input Effects on Degeneration in Prolonged Penicillin Chemostat Cultures: A Systems Analysis at Flux, Residual Glucose, Metabolite and Transcript Levels.
    Biotechnol Bioeng 2017 Sep 2. Epub 2017 Sep 2.
    DSM Biotechnology Center, Delft, The Netherlands.
    In the present work, by performing chemostat experiments at 400 and 600 RPM, two typical power inputs representative of industrial penicillin fermentation (P/V, 1.00 kW/m(3) in more remote zones and 3.83 kW/m(3) in the vicinity of the impellers, respectively) were scaled-down to bench-scale bioreactors. Read More

    Cover Image, Volume 114, Number 10, October 2017.
    Biotechnol Bioeng 2017 Oct;114(10)
    Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan.
    Cover Legend: The cover image, by Yuta Kurashina et al., is based on the Article Enzyme-free cell detachment mediated by resonance vibration with temperature modulation, DOI 10.1002/bit. Read More

    A dynamic metabolic flux analysis of ABE (acetone-butanol-ethanol) fermentation by Clostridium acetobutylicum ATCC 824, with riboflavin as a by-product.
    Biotechnol Bioeng 2017 Aug 29. Epub 2017 Aug 29.
    Research Laboratory in Applied Metabolic Engineering, Department of Chemical Engineering, École Polytechnique de Montréal, Montréal, Québec, Canada.
    The present study reveals that supplementing sodium acetate (NaAc) strongly stimulates riboflavin production in acetone-butanol-ethanol (ABE) fermentation by Clostridium acetobutylicum ATCC 824 with xylose as carbon source. Riboflavin production increased from undetectable concentrations to ∼0.2 g L(-1) (0. Read More

    Cell-Free Production of a Therapeutic Protein: Expression, Purification, and Characterization of Recombinant Streptokinase Using a CHO Lysate.
    Biotechnol Bioeng 2017 Aug 26. Epub 2017 Aug 26.
    Center for Advanced Sensor Technology, University of Maryland Baltimore County, Baltimore, Maryland, USA.
    The use of cell-free systems to produce recombinant proteins has grown rapidly over the past decade. In particular, cell-free protein synthesis (CFPS) systems based on mammalian cells provide alternative methods for the production of many proteins, including those that contain disulfide bonds, glycosylation and complex structures such as monoclonal antibodies. In the present study, we show robust production of turbo green fluorescent protein (tGFPi and streptokinase in a cell-free system using instrumented mini-bioreactors for highly reproducible protein production. Read More

    Cascading effect in bioprocessing-The impact of mild hypothermia on CHO cell behavior and host cell protein composition.
    Biotechnol Bioeng 2017 Aug 26. Epub 2017 Aug 26.
    Department of Chemical Engineering, Centre for Process Systems Engineering, Imperial College London, London, U.K.
    A major challenge in downstream purification of monoclonal antibodies (mAb) is the removal of host cell proteins (HCPs). Previous studies have shown that cell culture conditions significantly impact the HCP content at harvest. However, it is currently unclear how process conditions affect physiological changes in the host cell population, and how these changes, in turn, cascade down to change the HCP profile. Read More

    Recombinant RNA Polymerase from Geobacillus sp. GHH01 as tool for rapid generation of metagenomic RNAs using in vitro technologies.
    Biotechnol Bioeng 2017 Aug 26. Epub 2017 Aug 26.
    Microbiology and Biotechnology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststr, Hamburg, Germany.
    The exciting promises of functional metagenomics for the efficient discovery of novel biomolecules from nature are often hindered by factors associated with expression hosts. Aiming to shift functional metagenomics to a host independent innovative system, we here report on the cloning, heterologous expression, and reconstitution of an RNA polymerase (RNAP) from the thermophilic Geobacillus sp. GHH01 and in vitro transcription thereafter. Read More

    Biosimilars: Key regulatory considerations and similarity assessment tools.
    Biotechnol Bioeng 2017 Aug 26. Epub 2017 Aug 26.
    Pfizer Inc, BioTherapeutics Pharmaceutical Sciences, Groton, Connecticut.
    A biosimilar drug is defined in the US Food and Drug Administration (FDA) guidance document as a biopharmaceutical that is highly similar to an already licensed biologic product (referred to as the reference product) notwithstanding minor differences in clinically inactive components and for which there are no clinically meaningful differences in purity, potency, and safety between the two products. The development of biosimilars is a challenging, multistep process. Typically, the assessment of similarity involves comprehensive structural and functional characterization throughout the development of the biosimilar in an iterative manner and, if required by the local regulatory authority, an in vivo nonclinical evaluation, all conducted with direct comparison to the reference product. Read More

    Escherichia coli 'TatExpress' strains super-secrete human growth hormone into the bacterial periplasm by the Tat pathway.
    Biotechnol Bioeng 2017 Aug 26. Epub 2017 Aug 26.
    School of Biosciences, University of Kent, Ingram Building, Canterbury CT2 7NJ, UK.
    Numerous high-value proteins are secreted into the Escherichia coli periplasm by the General Secretory (Sec) pathway, but Sec-based production chassis cannot handle many potential target proteins. The Tat pathway offers a promising alternative because it transports fully folded proteins; however, yields have been too low for commercial use. To facilitate Tat export, we have engineered the TatExpress series of super-secreting strains by introducing the strong inducible bacterial promoter, ptac, upstream of the chromosomal tatABCD operon, to drive its expression in E. Read More

    Impact of Growth Mode, Phase and Rate on the Metabolic State of the Extremely Thermophilic Archaeon Pyrococcus furiosus.
    Biotechnol Bioeng 2017 Aug 25. Epub 2017 Aug 25.
    Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC.
    The archaeon Pyrococcus furiosus is emerging as a metabolic engineering platform for production of fuels and chemicals, such that more must be known about this organism's characteristics in bioprocessing contexts. Its ability to grow at temperatures from 70 to greater than 100°C and thereby avoid contamination, offers the opportunity for long duration, continuous bioprocesses as an alternative to batch systems. Towards that end, we analyzed the transcriptome of P. Read More

    Dynamic Monitoring of p53 Translocation to Mitochondria for the Analysis of Specific Inhibitors Using Luciferase-fragment Complementation.
    Biotechnol Bioeng 2017 Aug 19. Epub 2017 Aug 19.
    Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
    Intracellular protein translocation plays a pivotal role in regulating complex biological processes, including cell death. The tumor suppressor p53 is a transcription factor activated by DNA damage and oxidative stress that also translocates from the cytosol into the mitochondrial matrix to facilitate necrotic cell death. However, specific inhibitors of p53 mitochondrial translocation are largely unknown. Read More

    Comparative analysis of plant-produced, recombinant dimeric IgA against cell wall β-glucan of pathogenic fungi.
    Biotechnol Bioeng 2017 Aug 19. Epub 2017 Aug 19.
    Laboratory of Biotechnology, Agenzia Nazionale per le Nuove Tecnologie, l'Energia e lo Sviluppo Economico Sostenibile (ENEA), Research Center Casaccia, Rome, Italy.
    Immunoglobulins A (IgA) are crucially involved in protection of human mucosal surfaces from microbial pathogens. In this work, we devised and expressed in plants recombinant chimeric antifungal antibodies (Abs) of isotype A (IgA1, IgA2, and scFvFcA1), derived from a murine mAb directed to the fungal cell wall polysaccharide β-glucan which had proven able to confer protection against multiple pathogenic fungi. All recombinant IgA (rIgA) were expressed and correctly assembled in dimeric form in plants and evaluated for yield, antigen-binding efficiency and antifungal properties in vitro, in comparison with a chimeric IgG1 version. Read More

    A metabolic engineering strategy for producing free fatty acids by the Yarrowia lipolytica yeast based on impairment of glycerol metabolism.
    Biotechnol Bioeng 2017 Aug 19. Epub 2017 Aug 19.
    Bioresource Center Russian National Collection of Industrial Microorganisms (BRC VKPM), State Research Institute of Genetics and Selection of Industrial Microorganisms (GosNIIgenetika), 1-st Dorozhny pr., 1, Moscow 117545, Russia.
    In recent years, bio-based production of free fatty acids from renewable resources has attracted attention for their potential as precursors for the production of biofuels and biochemicals. In this study, the oleaginous yeast Yarrowia lipolytica was engineered to produce free fatty acids by eliminating glycerol metabolism. Free fatty acid production was monitored under lipogenic conditions with glycerol as a limiting factor. Read More

    Codelivery of anti-cancer agents via double-walled polymeric microparticles/injectable hydrogel: A promising approach for treatment of triple negative breast cancer.
    Biotechnol Bioeng 2017 Aug 19. Epub 2017 Aug 19.
    Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore.
    Triple negative breast cancer (TNBC) is an aggressive sub-type of breast cancer that rarely responds to conventional chemotherapy. Therefore, novel agents or new routes need to be developed to improve treatment efficacy and diminish severe side-effects of anti-cancer agents in TNBC patients. This study explores a novel localized co-delivery platform with potential application against TNBC. Read More

    CRISPRi repression of nonhomologous end-joining for enhanced genome engineering via homologous recombination in Yarrowia lipolytica.
    Biotechnol Bioeng 2017 Aug 19. Epub 2017 Aug 19.
    Chemical and Environmental Engineering, University of California Riverside, Riverside, California.
    In many organisms of biotechnological importance precise genome editing is limited by inherently low homologous recombination (HR) efficiencies. A number of strategies exist to increase the effectiveness of this native DNA repair pathway; however, most strategies rely on permanently disabling competing repair pathways, thus reducing an organism's capacity to repair naturally occurring double strand breaks. Here, we describe a CRISPR interference (CRISPRi) system for gene repression in the oleochemical-producing yeast Yarrowia lipolytica. Read More

    Kinetics based reaction optimization of enzyme catalyzed reduction of formaldehyde to methanol with synchronous cofactor regeneration.
    Biotechnol Bioeng 2017 Aug 23. Epub 2017 Aug 23.
    Department of Chemical and Biochemical Engineering, Center for BioProcess Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark.
    Enzymatic reduction of carbon dioxide (CO2 ) to methanol (CH3 OH) can be accomplished using a designed set-up of three oxidoreductases utilizing reduced pyridine nucleotide (NADH) as cofactor for the reducing equivalents electron supply. For this enzyme system to function efficiently a balanced regeneration of the reducing equivalents during reaction is required. Herein, we report the optimization of the enzymatic conversion of formaldehyde (CHOH) to CH3 OH by alcohol dehydrogenase, the final step of the enzymatic redox reaction of CO2 to CH3 OH, with kinetically synchronous enzymatic cofactor regeneration using either glucose dehydrogenase (System I) or xylose dehydrogenase (System II). Read More

    Recombinant Lactococcus lactis for efficient conversion of cellodextrins into L-lactic acid.
    Biotechnol Bioeng 2017 Aug 12. Epub 2017 Aug 12.
    Department of Life Sciences and Systems Biology, Structural and Functional Biochemistry, Laboratory of Proteomics and Metabolic Engineering of Prokaryotes, University of Turin, Torino, Italy.
    Lactic acid bacteria (LAB) are among the most interesting organisms for industrial processes with a long history of application as food starters and biocontrol agents, and an underexploited potential for biorefineries converting biomass into high-value compounds. Lactic acid (LA), their main fermentation product, is among the most requested chemicals owing to its broad range of applications. Notably, LA polymers, that is, polylactides, have high potential as biodegradable substitutes of fossil-derived plastics. Read More

    Incorporating LsrK AI-2 Quorum Quenching Capability in a Functionalized Biopolymer Capsule.
    Biotechnol Bioeng 2017 Aug 7. Epub 2017 Aug 7.
    Institute for Bioscience and Biotechnology Research (IBBR), University of Maryland, College Park, Maryland 2074.
    Antibacterial resistance is an issue of increasing severity as current antibiotics are losing their effectiveness and fewer antibiotics are being developed. New methods for combating bacterial virulence are required. Modulating molecular communication among bacteria can alter phenotype, including attachment to epithelia, biofilm formation and even toxin production. Read More

    Combination of traditional mutation and metabolic engineering to enhance ansamitocin P-3 production in Actinosynnema pretiosum.
    Biotechnol Bioeng 2017 Aug 7. Epub 2017 Aug 7.
    State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and Laboratory of Molecular Biochemical Engineering and Advanced Fermentation Technology, Department of Bioengineering, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
    Ansamitocin P-3 (AP-3) is a maytansinoid with its most compelling antitumor activity, however, the low production titer of AP-3 greatly restricts its wide commercial application. In this work, a combinatorial approach including random mutation and metabolic engineering was conducted to enhance AP-3 biosynthesis in Actinosynnema pretiosum. First, a mutant strain M was isolated by N-methyl-N'-nitro-N-nitrosoguanidine mutation, which could produce AP-3 almost threefold that of wild type (WT) in 48 deep-well plates. Read More

    Mechanisms of nitrous oxide (N2 O) formation and reduction in denitrifying biofilms.
    Biotechnol Bioeng 2017 Aug 7. Epub 2017 Aug 7.
    Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana.
    Nitrous oxide (N2 O) is a potent greenhouse gas that can be formed in wastewater treatment processes by ammonium oxidizing and denitrifying microorganisms. While N2 O emissions from suspended growth systems have been extensively studied, and some recent studies have addressed emissions from nitrifying biofilms, much less is known about N2 O emissions from denitrifying biofilm processes. This research used modeling to evaluate the mechanisms of N2 O formation and reduction in denitrifying biofilms. Read More

    Overproduction of L-tryptophan via simultaneous feed of glucose and anthranilic acid from recombinant E.coli W3110: kinetic modelling and process scale-up.
    Biotechnol Bioeng 2017 Aug 7. Epub 2017 Aug 7.
    Centre for Process Systems Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
    L-tryptophan is an essential amino acid widely used in food and pharmaceutical industries. However, its production via Escherichia coli fermentation suffers severely from both low glucose conversion efficiency and acetic acid inhibition, and to date effective process control methods have rarely been explored to facilitate its industrial scale production. To resolve these challenges, in the current research an engineered strain of Escherichia coli was used to overproduce L-tryptophan. Read More

    Alginate-gelatin encapsulation of human endothelial cells promoted angiogenesis in in vivo and in vitro milieu.
    Biotechnol Bioeng 2017 Aug 7. Epub 2017 Aug 7.
    Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
    Up to present, many advantages have been achieved in the field of cell-based therapies by applying sophisticated methodologies and delivery approaches. Microcapsules are capable to provide safe microenvironment for cells during transplantation in a simulated physiological 3D milieu. Here, we aimed to investigate the effect of alginate-gelatin encapsulation on angiogenic behavior of human endothelial cells over a period of 5 days. Read More

    Bidirectional reporter assay using HAL promoter and TOPFLASH improves specificity in high-throughput screening of Wnt inhibitors.
    Biotechnol Bioeng 2017 Jul 29. Epub 2017 Jul 29.
    Division of Clinical Genome Research, Advanced Clinical Research Center, Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
    Constitutive activation of Wnt signaling plays an important role in colorectal and liver tumorigenesis. Cell-based assays using synthetic TCF/LEF (T-cell factor/lymphoid enhancer factor) reporters, as readouts of β-catenin/TCF-dependent transcriptional activity, have contributed greatly to the discovery of small molecules that modulate Wnt signaling. In the present study, we report a novel screening method, called a bidirectional dual reporter assay. Read More

    Metabolic engineering of isopropyl alcohol-producing Escherichia coli strains with (13) C-metabolic flux analysis.
    Biotechnol Bioeng 2017 Jul 29. Epub 2017 Jul 29.
    Department of Bioinfomatic Engineering, Graduate School of Information Science and Technology, Osaka University, Osaka, Japan.
    Metabolic engineering of isopropyl alcohol (IPA)-producing Escherichia coli strains was conducted along with (13) C-metabolic flux analysis (MFA). A metabolically engineered E. coli strain expressing the adc gene derived from Clostridium acetobutylicum and the IPADH gene from C. Read More

    NMR investigation of water diffusion in different biofilm structures.
    Biotechnol Bioeng 2017 Jul 29. Epub 2017 Jul 29.
    Department of Water Chemistry and Water Technology, Engler-Bunte-Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany.
    Mass transfer in biofilms is determined by diffusion. Different mostly invasive approaches have been used to measure diffusion coefficients in biofilms, however, data on heterogeneous biomass under realistic conditions is still missing. To non-invasively elucidate fluid-structure interactions in complex multispecies biofilms pulsed field gradient-nuclear magnetic resonance (PFG-NMR) was applied to measure the water diffusion in five different types of biomass aggregates: one type of sludge flocs, two types of biofilm, and two types of granules. Read More

    Controlling localization of Escherichia coli populations using a two-part synthetic motility circuit: An accelerator and brake.
    Biotechnol Bioeng 2017 Jul 29. Epub 2017 Jul 29.
    Fischell Department of Bioengineering, University of Maryland, College Park, Maryland.
    Probiotics, whether taken as capsules or consumed in foods, have been regarded as safe for human use by regulatory agencies. Being living cells, they serve as "tunable" factories for the synthesis of a vast array of beneficial molecules. The idea of reprogramming probiotics to act as controllable factories, producing potential therapeutic molecules under user-specified conditions, represents a new and powerful concept in drug synthesis and delivery. Read More

    A review on comparative mechanistic studies of antimicrobial peptides against archaea.
    Biotechnol Bioeng 2017 Jul 22. Epub 2017 Jul 22.
    School of Chemical Sciences, University of Auckland, Auckland, New Zealand.
    Archaea was until recently considered as a third domain of life in addition to bacteria and eukarya but recent studies support the existence of only two superphyla (bacteria and archaea). The fundamental differences between archaeal, bacterial, and eukaryal cells are probably the main reasons for the comparatively lower susceptibility of archaeal strains to current antimicrobial agents. The possible emerging pathogenicity of archaea and the role of archaeal methanogens in methane emissions, a potent greenhouse gas, has led many researchers to examine the sensitivity patterns of archaea and make attempts to find agents that have significant anti-archaeal activity. Read More

    Development of aptamers against unpurified proteins.
    Biotechnol Bioeng 2017 Jul 22. Epub 2017 Jul 22.
    Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan.
    SELEX (Systematic Evolution of Ligands by EXponential enrichment) has been widely used for the generation of aptamers against target proteins. However, its requirement for pure target proteins remains a major problem in aptamer selection, as procedures for protein purification from crude bio-samples are not only complicated but also time and labor consuming. This is because native proteins can be found in a large number of diverse forms because of posttranslational modifications and their complicated molecular conformations. Read More

    Preselection of recombinant gene integration sites enabling high transcription rates in CHO cells using alternate start codons and recombinase mediated cassette exchange.
    Biotechnol Bioeng 2017 Jul 22. Epub 2017 Jul 22.
    Austrian Centre of Industrial Biotechnology (ACIB), Graz, Austria.
    Site-specific recombinase mediated cassette exchange (RMCE) enables the transfer of the gene of interest (GOI) into pre-selected genomic locations with defined expression properties. For the generation of recombinant production cell lines, this has the advantage that screening for high transcription rates at the genome integration site would be required only once, with the possibility to reuse the selected site for new products. Here, we describe a strategy that aims at the selection of transcriptionally active genome integration sites in Chinese Hamster Ovary (CHO) cells by using alternate start codons in the surface reporter protein CD4, in combination with FACS sorting for high expressers. Read More

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