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Biotechnology and Bioengineering

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https://www.readbyqxmd.com/read/28802003/recombinant-lactococcus-lactis-for-efficient-conversion-of-cellodextrins-into-l-lactic-acid
#1
Chiara Gandini, Loredana Tarraran, Denis Kalemasi, Enrica Pessione, Roberto Mazzoli
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, i.e., polylactides, have high potential as biodegradable substitutes of fossil-derived plastics...
August 12, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28782813/incorporating-lsrk-ai-2-quorum-quenching-capability-in-a-functionalized-biopolymer-capsule
#2
Melissa K Rhoads, Pricila Hauk, Jessica Terrell, Chen-Yu Tsao, Hyuntaek Oh, Srinivasa R Raghavan, Sheref S Mansy, Gregory F Payne, William E Bentley
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. Intercepting and modulating communication networks provide a means to attenuate virulence without directly interacting with the bacteria of interest...
August 7, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28782796/combination-of-traditional-mutation-and-metabolic-engineering-to-enhance-ansamitocin-p-3-production-in-actinosynnema-pretiosum
#3
Zhi-Qiang Du, Yuan Zhang, Zhi-Gang Qian, Han Xiao, Jian-Jiang Zhong
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. Firstly, a mutant strain M was isolated by N-methyl-N'-nitro-N-nitrosoguanidine mutation, which could produce AP-3 almost 3-fold that of wild type in 48 deep-well plates. Then, by overexpressing key biosynthetic genes asmUdpg and asm13-17 in the M strain, a further 60% increase of AP-3 production in 250-mL shake flasks was achieved in the engineered strain M-asmUdpg:asm13-17 compared to the M strain, and its maximum AP-3 production reached 582...
August 7, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28782795/mechanisms-of-nitrous-oxide-n2-o-formation-and-reduction-in-denitrifying-biofilms
#4
Fabrizio Sabba, Cristian Picioreanu, Robert Nerenberg
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. The kinetic model included formation and consumption of key denitrification species, including nitrate (NO3(-) ), nitrite (NO2(-) ), nitric oxide (NO), and N2 O...
August 7, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28782794/overproduction-of-l-tryptophan-via-simultaneous-feed-of-glucose-and-anthranilic-acid-from-recombinant-e-coli-w3110-kinetic-modelling-and-process-scale-up
#5
Keju Jing, Yuanwei Tang, Chuanyi Yao, Ehecatl Antonio Del Rio-Chanona, Xueping Ling, Dongda Zhang
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. To achieve this, a novel dynamic control strategy which incorporates an optimised anthranilic acid feeding into a dissolved oxygen-stat (DO-stat) glucose feeding framework was proposed for the first time...
August 7, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28782793/alginate-gelatin-encapsulation-of-human-endothelial-cells-promoted-angiogenesis-in-in-vivo-and-in-vitro-milieu
#6
Sorour Nemati, Aysa Rezabakhsh, Ali Baradar Khoshfetrat, Alireza Nourazarian, Çığır Biray Avci, Bakiye Goker Bagca, Hamed Alizadeh Sardroud, Majid Khaksar, Mahdi Ahmadi, Aref Delkhosh, Emel Sokullu, Reza Rahbarghazi
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. Human umbilical vein endothelial cells were encapsulated by alginate-gelatin substrate and incubated for 5 days...
August 7, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28755500/bidirectional-reporter-assay-using-hal-promoter-and-topflash-improves-specificity-in-high-throughput-screening-of-wnt-inhibitors
#7
Kiyoshi Yamaguchi, Chi Zhu, Tomoyuki Ohsugi, Yuko Yamaguchi, Tsuneo Ikenoue, Yoichi Furukawa
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. Integrated transcriptome analysis identified a histidine ammonia-lyase gene (HAL) that was negatively regulated by β-catenin/TCF-dependent transcriptional activity...
July 29, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28755490/metabolic-engineering-of-isopropyl-alcohol-producing-escherichia-coli-strains-with-13-c-metabolic-flux-analysis
#8
Nobuyuki Okahashi, Fumio Matsuda, Katsunori Yoshikawa, Tomokazu Shirai, Yoshiko Matsumoto, Mitsufumi Wada, Hiroshi Shimizu
Metabolic engineering of isopropyl alcohol (IPA)-producing E. 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. beijerinckii did not produce IPA during its exponential growth phase in the aerobic batch culture. (13) C-MFA was carried out, and revealed a deficiency in NADPH regeneration for IPA production in growth phase. Based on these findings, we used nitrogen-starved culture conditions to reduce NADPH consumption for biomass synthesis...
July 29, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28755486/nmr-investigation-of-water-diffusion-in-different-biofilm-structures
#9
Maria P Herrling, Jessica Weisbrodt, Catherine M Kirkland, Nathan H Williamson, Susanne Lackner, Sarah L Codd, Joseph D Seymour, Gisela Guthausen, Harald Horn
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...
July 29, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28755474/controlling-localization-of-e-coli-populations-using-a-two-part-synthetic-motility-circuit-an-accelerator-and-brake
#10
Ryan McKay, Pricila Hauk, Hsuan-Chen Wu, Alex Eli Pottash, Wu Shang, Jessica Terrell, Gregory F Payne, William E Bentley
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. Probiotics that serve as drug delivery vehicles pose several challenges, one being targeting (similar to nanoparticle approaches)...
July 29, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28734066/a-review-on-comparative-mechanistic-studies-of-antimicrobial-peptides-against-archaea
#11
REVIEW
Kyriakos G Varnava, Ron S Ronimus, Vijayalekshmi Sarojini
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...
July 22, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28734049/development-of-aptamers-against-unpurified-proteins
#12
Shinichi Goto, Kaori Tsukakoshi, Kazunori Ikebukuro
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 labour 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...
July 22, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28734047/preselection-of-recombinant-gene-integration-sites-enabling-high-transcription-rates-in-cho-cells-using-alternate-start-codons-and-recombinase-mediated-cassette-exchange
#13
Martina Baumann, Elisabeth Gludovacz, Natalie Sealover, Scott Bahr, Henry George, Nan Lin, Kevin Kayser, Nicole Borth
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...
July 22, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28710860/coupling-the-pretreatment-and-hydrolysis-of-lignocellulosic-biomass-by-the-expression-of-beta-xylosidases
#14
Lucía Martín Pérez, Laura Benítez Casanova, Antonio Javier Moreno Pérez, Dolores Pérez Gómez, Sandra Gavaldá Martín, Laura Ledesma-García, Noelia Valbuena, Bruno Díez García, Francisco Manuel Reyes-Sosa
Thermochemical pretreatment and enzymatic hydrolysis are the areas contributing most to the operational costs of second generation ethanol in lignocellulosic biorefineries. The improvement of lignocellulosic enzyme cocktails has been significant in the recent years. Although the needs for the reduction of the energy intensity and chemical consumption in the pretreatment step are well known, the reduction of the severity of the process strongly affects the enzymatic hydrolysis yield. To explore the formulation requirements of the well known cellulolytic cocktail from Myceliophthora thermophila on mild pretreated raw materials, this cocktail was tested on steam exploded corn stover without acid impregnation...
July 15, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28710857/ros-mediated-selection-for-increased-nadph-availability-in-escherichia-coli
#15
REVIEW
T Steele Reynolds, Colleen M Courtney, Keesha E Erickson, Lisa M Wolfe, Anushree Chatterjee, Prashant Nagpal, Ryan T Gill
The economical production of chemicals and fuels by microbial processes remains an intense area of interest in biotechnology. A key limitation in such efforts concerns the availability of key co-factors, in this case NADPH, required for target pathways. Many of the strategies pursued for increasing NADPH availability in Escherichia coli involve manipulations to the central metabolism, which can create redox imbalances and overall growth defects. In this study we used a reactive oxygen species based selection to search for novel methods of increasing NADPH availability...
July 15, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28710856/quantitative-intracellular-flux-modeling-and-applications-in-biotherapeutic-development-and-production-using-cho-cell-cultures
#16
REVIEW
Zhuangrong Huang, Dong-Yup Lee, Seongkyu Yoon
Chinese hamster ovary (CHO) cells have been widely used for producing many recombinant therapeutic proteins. Constraint-based modeling, such as flux balance analysis (FBA) and metabolic flux analysis (MFA), has been developing rapidly for the quantification of intracellular metabolic flux distribution at a systematic level. Such methods would produce detailed maps of flows through metabolic networks, which contribute significantly to better understanding of metabolism in cells. Although these approaches have been extensively established in microbial systems, their application to mammalian cells is sparse...
July 15, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28710854/opportunities-and-challenges-of-real-time-release-testing-in-biopharmaceutical-manufacturing
#17
REVIEW
Mo Jiang, Kristen Severson, J Christopher Love, Helena Madden, Patrick Swann, Li Zang, Richard D Braatz
Real-time release testing (RTRT) is defined as "the ability to evaluate and ensure the quality of in-process and/or final drug product based on process data, which typically includes a valid combination of measured material attributes and process controls" (ICH Q8(R2)). This article discusses sensors (process analytical technology, PAT) and control strategies that enable RTRT for the spectrum of critical quality attributes (CQAs) in biopharmaceutical manufacturing. Case studies from the small-molecule and biologic pharmaceutical industry are described to demonstrate how RTRT can be facilitated by integrated manufacturing and multivariable control strategies to ensure the quality of products...
July 15, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28710851/generation-of-apoptosis-resistant-hek293-cells-with-crispr-cas-mediated-quadruple-gene-knockout-for-improved-protein-and-virus-production
#18
Weifeng Zhang, Dan Xiao, Linlin Shan, Junli Zhao, Qinwen Mao, Haibin Xia
Apoptosis has important functions during pathophysiologic processes. However, from a biopharmaceutical point of view, active apoptosis of host cells is undesirable during viral packaging or protein expression, because it decreases the efficiency of viral or protein production. Here we used the CRISPR/Cas technique to knock out four pro-apoptotic genes, Caspase3, Caspase6, Caspase7 and AIF1, in HEK293 cells, and successfully produced an apoptosis-resistant cell line. Furthermore, this cell line showed higher expression levels of pro-apoptotic proteins and higher packaging efficiency for the virus carrying these proteins than control HEK293 cells...
July 15, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28695999/to-be-certain-about-the-uncertainty-bayesian-statistics-for-13-c-metabolic-flux-analysis
#19
Axel Theorell, Samuel Leweke, Wolfgang Wiechert, Katharina Nöh
(13) C Metabolic Fluxes Analysis ((13) C MFA) remains to be the most powerful approach to determine intracellular metabolic reaction rates. Decisions on strain engineering and experimentation heavily rely upon the certainty with which these fluxes are estimated. For uncertainty quantification, the vast majority of (13) C MFA studies relies on confidence intervals from the paradigm of Frequentist statistics. However, it is well known that the confidence intervals for a given experimental outcome are not uniquely defined...
July 11, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28691262/metabolic-modeling-to-identify-engineering-targets-for-komagataella-phaffii-the-effect-of-biomass-composition-on-gene-target-identification
#20
Ayca Cankorur-Cetinkaya, Duygu Dikicioglu, Stephen G Oliver
Genome-scale metabolic models are valuable tools for the design of novel strains of industrial microorganisms, such as Komagataella phaffii (syn. Pichia pastoris). However, as is the case for many industrial microbes, there is no executable metabolic model for K. phaffiii that confirms to current standards by providing the metabolite and reactions IDs, to facilitate model extension and reuse, and gene-reaction associations to enable identification of targets for genetic manipulation. In order to remedy this deficiency, we decided to reconstruct the genome-scale metabolic model of K...
July 10, 2017: Biotechnology and Bioengineering
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