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Microbial Cell Factories

Haisu Shi, Xue Luo, Rina Wu, Xiqing Yue
Dunaliella salina is a unicellular green alga with a high α-linolenic acid (ALA) level, but a low eicosapentaenoic acid (EPA) level. In a previous analysis of the catalytic activity of delta 6 fatty acid desaturase (FADS6) from various species, FADS6 from Thalassiosira pseudonana (TpFADS6), a marine diatom, showed the highest catalytic activity for ALA. In this study, to enhance EPA production in D. salina, FADS6 from D. salina (DsFADS6) was identified, and substrate specificities for DsFADS6 and TpFADS6 were characterized...
January 13, 2018: Microbial Cell Factories
Milica Popovic, Elisa Mazzega, Barbara Toffoletto, Ario de Marco
BACKGROUND: The thorough understanding of the physiological and pathological processes mediated by extracellular vesicles (EVs) is challenged by purification methods which are cumbersome, not reproducible, or insufficient to yield homogeneous material. Chromatography based on both ion-exchange and immune-capture can represent an effective method to improve EV purification and successive analysis. METHODS: Cell culture supernatant was used as a model sample for assessing the capacity of anion-exchange chromatography to separate distinct EV fractions and to isolate nanobodies by direct panning on whole EVs to recover binders specific for the native conformation of EV-surface epitopes and suitable to develop EV immune-capture reagents...
January 13, 2018: Microbial Cell Factories
Scott Bottoms, Quinn Dickinson, Mick McGee, Li Hinchman, Alan Higbee, Alex Hebert, Jose Serate, Dan Xie, Yaoping Zhang, Joshua J Coon, Chad L Myers, Robert Landick, Jeff S Piotrowski
BACKGROUND: Gamma valerolactone (GVL) treatment of lignocellulosic bomass is a promising technology for degradation of biomass for biofuel production; however, GVL is toxic to fermentative microbes. Using a combination of chemical genomics with the yeast (Saccharomyces cerevisiae) deletion collection to identify sensitive and resistant mutants, and chemical proteomics to monitor protein abundance in the presence of GVL, we sought to understand the mechanism toxicity and resistance to GVL with the goal of engineering a GVL-tolerant, xylose-fermenting yeast...
January 12, 2018: Microbial Cell Factories
Jaehyun Park, Hyojung Shin, Sun-Mi Lee, Youngsoon Um, Han Min Woo
BACKGROUND: The construction of microbial cell factories requires cost-effective and rapid strain development through metabolic engineering. Recently, RNA-guided CRISPR technologies have been developed for metabolic engineering of industrially-relevant host. RESULTS: To demonstrate the application of the CRISPR interference (CRISPRi), we developed two-plasmid CRISPRi vectors and applied the CRISPRi in Corynebacterium glutamicum to repress single target genes and double target genes simultaneously...
January 9, 2018: Microbial Cell Factories
Francine Piubeli, Manuel Salvador, Montserrat Argandoña, Joaquín J Nieto, Vicente Bernal, Jose M Pastor, Manuel Cánovas, Carmen Vargas
BACKGROUND: The halophilic bacterium Chromohalobacter salexigens is a natural producer of ectoines, compatible solutes with current and potential biotechnological applications. As production of ectoines is an osmoregulated process that draws away TCA intermediates, bacterial metabolism needs to be adapted to cope with salinity changes. To explore and use C. salexigens as cell factory for ectoine(s) production, a comprehensive knowledge at the systems level of its metabolism is essential...
January 9, 2018: Microbial Cell Factories
Simon Rosowski, Stefan Becker, Lars Toleikis, Bernhard Valldorf, Julius Grzeschik, Deniz Demir, Iris Willenbücher, Ramona Gaa, Harald Kolmar, Stefan Zielonka, Simon Krah
BACKGROUND: Yeast surface display (YSD) has proven to be a versatile platform technology for antibody discovery. However, the construction of antibody Fab libraries typically is a tedious three-step process that involves the generation of heavy chain as well as light chain display plasmids in different haploid yeast strains followed by yeast mating. RESULTS: Within this study, we aimed at implementing a focused Golden Gate Cloning approach for the generation of YSD libraries...
January 9, 2018: Microbial Cell Factories
Ting-Lei Tao, Feng-Jie Cui, Xiao-Xiao Chen, Wen-Jing Sun, Da-Ming Huang, Jinsong Zhang, Yan Yang, Di Wu, Wei-Min Liu
BACKGROUND: Mushroom showed pellet, clump and/or filamentous mycelial morphologies during submerged fermentation. Addition of microparticles including Talc (magnesium silicate), aluminum oxide and titanium oxide could control mycelial morphologies to improve mycelia growth and secondary metabolites production. Here, effect of microparticle Talc (45 μm) addition on the mycelial morphology, fermentation performance, monosaccharide compositions of polysaccharides and enzymes activities associated with polysaccharide synthesis in G...
January 6, 2018: Microbial Cell Factories
Mohamed Belal Hamed, Spyridoula Karamanou, Solveig Ólafsdottir, Joana Sofia Martins Basílio, Kenneth Simoens, Kostantinos C Tsolis, Lieve Van Mellaert, Eik Elísabet Guðmundsdóttir, Gudmundur Oli Hreggvidsson, Jozef Anné, Kristel Bernaerts, Olafur H Fridjonsson, Anastassios Economou
BACKGROUND: The gene encoding a thermostable cellulase of family 12 was previously isolated from a Rhodothermus marinus through functional screening. CelA is a protein of 260 aminoacyl residues with a 28-residue amino-terminal signal peptide. Mature CelA was poorly synthesized in some Escherichia coli strains and not at all in others. Here we present an alternative approach for its heterologous production as a secreted polypeptide in Streptomyces. RESULTS: CelA was successfully over-expressed as a secreted polypeptide in Streptomyces lividans TK24...
December 23, 2017: Microbial Cell Factories
Yan Ren, Yuetong Ji, Lin Teng, Heping Zhang
BACKGROUND: As microbial cultures are comprised of heterogeneous cells that differ according to their size and intracellular concentrations of DNA, proteins, and other constituents, the detailed identification and discrimination of the growth phases of bacterial populations in batch culture is challenging. Cell analysis is indispensable for quality control and cell enrichment. METHODS: In this paper, we report the results of our investigation on the use of single-cell Raman spectrometry (SCRS) for real-time analysis and prediction of cells in different growth phases during batch culture of Lactobacillus (L...
December 23, 2017: Microbial Cell Factories
Cheng Cheng, Shanshan Wu, Lupeng Cui, Yulu Wu, Tianyue Jiang, Bingfang He
BACKGROUND: The high level of excretion and rapid folding ability of β-fructofuranosidase (β-FFase) in Escherichia coli has suggested that β-FFase from Arthrobacter arilaitensis NJEM01 can be developed as a fusion partner. METHODS: Based on the modified Wilkinson and Harrison algorithm and the preliminary verification of the solubility-enhancing ability of β-FFase truncations, three β-FFase truncations (i.e., Ffu209, Ffu217, and Ffu312) with a native signal peptide were selected as novel Ffu fusion tags...
December 21, 2017: Microbial Cell Factories
Xiaozhou Zou, Guochao Wu, Stefan Stagge, Lin Chen, Leif J Jönsson, Feng F Hong
BACKGROUND: Through pretreatment and enzymatic saccharification lignocellulosic biomass has great potential as a low-cost feedstock for production of bacterial nanocellulose (BNC), a high value-added microbial product, but inhibitors formed during pretreatment remain challenging. In this study, the tolerance to lignocellulose-derived inhibitors of three new BNC-producing strains were compared to that of Komagataeibacter xylinus ATCC 23770. Inhibitors studied included furan aldehydes (furfural and 5-hydroxymethylfurfural) and phenolic compounds (coniferyl aldehyde and vanillin)...
December 21, 2017: Microbial Cell Factories
Eric Johansen
Industrial fermentations based on micro-organisms such as the lactic acid bacteria (LAB) play an important role in several industries globally and represent multi-billion Euro/dollar businesses. LAB provide a natural way to produce safe, sustainable, and environmentally friendly products for a variety of industries. Product innovation is a key requirement for these industries to survive and grow globally. However, the development of new products may be affected by two man-made constraints; the Nagoya Protocol on benefit sharing and the opposition to the use of modern biotechnology for strain improvement...
December 21, 2017: Microbial Cell Factories
Rubing Zhang, Yujin Cao, Wei Liu, Mo Xian, Huizhou Liu
BACKGROUND: Phloroglucinol is an important chemical which has been successfully produced by engineered Escherichia coli. However, the toxicity of phloroglucinol can enormously inhibit E. coli cell growth and viability, and the productivity is still too low and not economically feasible for industrial applications. Therefore, strain tolerance to toxic metabolites remains a key issue during the production of chemicals using biological processes. RESULTS: In the present work, we examined the impact of the native GroESL chaperone system with different overexpression levels on phloroglucinol tolerance and production in E...
December 19, 2017: Microbial Cell Factories
Esther Giesselmann, Björn Becker, Manfred J Schmitt
BACKGROUND: Virus infected killer strains of the baker's yeast Saccharomyces cerevisiae secrete protein toxins such as K28, K1, K2 and Klus which are lethal to sensitive yeast strains of the same or related species. K28 is somewhat unique as it represents an α/β heterodimeric protein of the A/B toxin family which, after having bound to the surface of sensitive target cells, is taken up by receptor-mediated endocytosis and transported through the secretory pathway in a retrograde manner...
December 19, 2017: Microbial Cell Factories
Grietje Kuipers, Alexandros Karyolaimos, Zhe Zhang, Nurzian Ismail, Gianluca Trinco, David Vikström, Dirk Jan Slotboom, Jan-Willem de Gier
BACKGROUND: To optimize the production of membrane and secretory proteins in Escherichia coli, it is critical to harmonize the expression rates of the genes encoding these proteins with the capacity of their biogenesis machineries. Therefore, we engineered the Lemo21(DE3) strain, which is derived from the T7 RNA polymerase-based BL21(DE3) protein production strain. In Lemo21(DE3), the T7 RNA polymerase activity can be modulated by the controlled co-production of its natural inhibitor T7 lysozyme...
December 16, 2017: Microbial Cell Factories
Till Tiso, Rabea Zauter, Hannah Tulke, Bernd Leuchtle, Wing-Jin Li, Beate Behrens, Andreas Wittgens, Frank Rosenau, Heiko Hayen, Lars Mathias Blank
BACKGROUND: Rhamnolipids are biosurfactants featuring surface-active properties that render them suitable for a broad range of industrial applications. These properties include their emulsification and foaming capacity, critical micelle concentration, and ability to lower surface tension. Further, aspects like biocompatibility and environmental friendliness are becoming increasingly important. Rhamnolipids are mainly produced by pathogenic bacteria like Pseudomonas aeruginosa. We previously designed and constructed a recombinant Pseudomonas putida KT2440, which synthesizes rhamnolipids by decoupling production from host-intrinsic regulations and cell growth...
December 14, 2017: Microbial Cell Factories
Jinny L Liu, Lisa C Shriver-Lake, George P Anderson, Dan Zabetakis, Ellen R Goldman
BACKGROUND: A key advantage of recombinant antibody technology is the ability to optimize and tailor reagents. Single domain antibodies (sdAbs), the recombinantly produced variable domains derived from camelid and shark heavy chain antibodies, provide advantages of stability and solubility and can be further engineered to enhance their properties. In this study, we generated sdAbs specific for Ebola virus envelope glycoprotein (GP) and increased their stability to expand their utility for use in austere locals...
December 12, 2017: Microbial Cell Factories
Ah-Reum Park, Jin-Sook Kim, Seung-Won Jang, Young-Gyun Park, Bong-Seong Koo, Hyeon-Cheol Lee
BACKGROUND: Lactulose, a synthetic disaccharide, has received increasing interest due to its role as a prebiotic, specifically proliferating Bifidobacilli and Lactobacilli and enhancing absorption of calcium and magnesium. The use of cellobiose 2-epimerase (CE) is considered an interesting alternative for industrial production of lactulose. CE reversibly converts D-glucose residues into D-mannose residues at the reducing end of unmodified β-1,4-linked oligosaccharides, including β-1,4-mannobiose, cellobiose, and lactose...
December 12, 2017: Microbial Cell Factories
Arthur R Gorter de Vries, Philip A de Groot, Marcel van den Broek, Jean-Marc G Daran
BACKGROUND: The ease of use of CRISPR-Cas9 reprogramming, its high efficacy, and its multiplexing capabilities have brought this technology at the forefront of genome editing techniques. Saccharomyces pastorianus is an aneuploid interspecific hybrid of Saccharomyces cerevisiae and Saccharomyces eubayanus that has been domesticated for centuries and is used for the industrial fermentation of lager beer. For yet uncharacterised reasons, this hybrid yeast is far more resilient to genetic alteration than its ancestor S...
December 5, 2017: Microbial Cell Factories
Pei Yu Lim, Lee Ling Tan, Dave Siak-Wei Ow, Fong T Wong
BACKGROUND: Lactic acid bacteria are a family of "generally regarded as safe" organisms traditionally used for food fermentation. In recent years, they have started to emerge as potential chassis for heterologous protein production. And more recently, due to their beneficial properties in the gut, they have been examined as potential candidates for mucosal delivery vectors, especially for acid-sensitive enzymes. One such application would be the delivery of gluten-digesting endopeptidases for the treatment of celiac disease...
December 5, 2017: Microbial Cell Factories
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