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Publisher: Springer-Verlag (Total: 2351 journals)

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Showing 1 - 200 of 2351 Journals sorted alphabetically
3D Printing in Medicine     Open Access   (Followers: 2)
3D Research     Hybrid Journal   (Followers: 21, SJR: 0.222, CiteScore: 1)
4OR: A Quarterly J. of Operations Research     Hybrid Journal   (Followers: 10, SJR: 0.825, CiteScore: 1)
AAPS J.     Hybrid Journal   (Followers: 25, SJR: 1.118, CiteScore: 4)
AAPS PharmSciTech     Hybrid Journal   (Followers: 7, SJR: 0.752, CiteScore: 3)
Abdominal Radiology     Hybrid Journal   (Followers: 18, SJR: 0.866, CiteScore: 2)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 4, SJR: 0.439, CiteScore: 0)
Academic Psychiatry     Full-text available via subscription   (Followers: 30, SJR: 0.53, CiteScore: 1)
Academic Questions     Hybrid Journal   (Followers: 8, SJR: 0.106, CiteScore: 0)
Accreditation and Quality Assurance: J. for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 31, SJR: 0.316, CiteScore: 1)
Acoustical Physics     Hybrid Journal   (Followers: 11, SJR: 0.359, CiteScore: 1)
Acoustics Australia     Hybrid Journal   (SJR: 0.232, CiteScore: 1)
Acta Analytica     Hybrid Journal   (Followers: 7, SJR: 0.367, CiteScore: 0)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1, SJR: 0.675, CiteScore: 1)
Acta Biotheoretica     Hybrid Journal   (Followers: 4, SJR: 0.284, CiteScore: 1)
Acta Diabetologica     Hybrid Journal   (Followers: 19, SJR: 1.587, CiteScore: 3)
Acta Endoscopica     Hybrid Journal   (Followers: 1)
acta ethologica     Hybrid Journal   (Followers: 4, SJR: 0.769, CiteScore: 1)
Acta Geochimica     Hybrid Journal   (Followers: 7, SJR: 0.24, CiteScore: 1)
Acta Geodaetica et Geophysica     Hybrid Journal   (Followers: 3, SJR: 0.305, CiteScore: 1)
Acta Geophysica     Hybrid Journal   (Followers: 11, SJR: 0.312, CiteScore: 1)
Acta Geotechnica     Hybrid Journal   (Followers: 7, SJR: 1.588, CiteScore: 3)
Acta Informatica     Hybrid Journal   (Followers: 5, SJR: 0.517, CiteScore: 1)
Acta Mathematica     Hybrid Journal   (Followers: 12, SJR: 7.066, CiteScore: 3)
Acta Mathematica Hungarica     Hybrid Journal   (Followers: 2, SJR: 0.452, CiteScore: 1)
Acta Mathematica Sinica, English Series     Hybrid Journal   (Followers: 6, SJR: 0.379, CiteScore: 1)
Acta Mathematica Vietnamica     Hybrid Journal   (SJR: 0.27, CiteScore: 0)
Acta Mathematicae Applicatae Sinica, English Series     Hybrid Journal   (SJR: 0.208, CiteScore: 0)
Acta Mechanica     Hybrid Journal   (Followers: 22, SJR: 1.04, CiteScore: 2)
Acta Mechanica Sinica     Hybrid Journal   (Followers: 5, SJR: 0.607, CiteScore: 2)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7, SJR: 0.576, CiteScore: 2)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.638, CiteScore: 1)
Acta Neurochirurgica     Hybrid Journal   (Followers: 7, SJR: 0.822, CiteScore: 2)
Acta Neurologica Belgica     Hybrid Journal   (Followers: 2, SJR: 0.376, CiteScore: 1)
Acta Neuropathologica     Hybrid Journal   (Followers: 4, SJR: 7.589, CiteScore: 12)
Acta Oceanologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.334, CiteScore: 1)
Acta Physiologiae Plantarum     Hybrid Journal   (Followers: 3, SJR: 0.574, CiteScore: 2)
Acta Politica     Hybrid Journal   (Followers: 19, SJR: 0.605, CiteScore: 1)
Activitas Nervosa Superior     Hybrid Journal   (SJR: 0.147, CiteScore: 0)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 8, SJR: 0.103, CiteScore: 0)
ADHD Attention Deficit and Hyperactivity Disorders     Hybrid Journal   (Followers: 27, SJR: 0.72, CiteScore: 2)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Administration and Policy in Mental Health and Mental Health Services Research     Partially Free   (Followers: 18, SJR: 1.005, CiteScore: 2)
Adsorption     Hybrid Journal   (Followers: 5, SJR: 0.703, CiteScore: 2)
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 4, SJR: 0.698, CiteScore: 1)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 38, SJR: 0.956, CiteScore: 2)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 20, SJR: 0.812, CiteScore: 1)
Advances in Contraception     Hybrid Journal   (Followers: 3)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 58, SJR: 1.09, CiteScore: 1)
Advances in Gerontology     Partially Free   (Followers: 8, SJR: 0.144, CiteScore: 0)
Advances in Health Sciences Education     Hybrid Journal   (Followers: 33, SJR: 1.64, CiteScore: 2)
Advances in Manufacturing     Hybrid Journal   (Followers: 3, SJR: 0.475, CiteScore: 2)
Advances in Polymer Science     Hybrid Journal   (Followers: 46, SJR: 1.04, CiteScore: 3)
Advances in Therapy     Hybrid Journal   (Followers: 5, SJR: 1.075, CiteScore: 3)
Aegean Review of the Law of the Sea and Maritime Law     Hybrid Journal   (Followers: 7)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2, SJR: 0.517, CiteScore: 1)
Aerobiologia     Hybrid Journal   (Followers: 3, SJR: 0.673, CiteScore: 2)
Aesthetic Plastic Surgery     Hybrid Journal   (Followers: 11, SJR: 0.825, CiteScore: 1)
African Archaeological Review     Hybrid Journal   (Followers: 21, SJR: 0.862, CiteScore: 1)
Afrika Matematika     Hybrid Journal   (Followers: 1, SJR: 0.235, CiteScore: 0)
AGE     Hybrid Journal   (Followers: 7)
Ageing Intl.     Hybrid Journal   (Followers: 7, SJR: 0.39, CiteScore: 1)
Aggiornamenti CIO     Hybrid Journal   (Followers: 1)
Aging Clinical and Experimental Research     Hybrid Journal   (Followers: 3, SJR: 0.67, CiteScore: 2)
Agricultural Research     Hybrid Journal   (Followers: 6, SJR: 0.276, CiteScore: 1)
Agriculture and Human Values     Open Access   (Followers: 15, SJR: 1.173, CiteScore: 3)
Agroforestry Systems     Open Access   (Followers: 20, SJR: 0.663, CiteScore: 1)
Agronomy for Sustainable Development     Open Access   (Followers: 15, SJR: 1.864, CiteScore: 6)
AI & Society     Hybrid Journal   (Followers: 9, SJR: 0.227, CiteScore: 1)
AIDS and Behavior     Hybrid Journal   (Followers: 14, SJR: 1.792, CiteScore: 3)
Air Quality, Atmosphere & Health     Hybrid Journal   (Followers: 4, SJR: 0.862, CiteScore: 3)
Akupunktur & Aurikulomedizin     Full-text available via subscription   (Followers: 1)
Algebra and Logic     Hybrid Journal   (Followers: 6, SJR: 0.531, CiteScore: 0)
Algebra Universalis     Hybrid Journal   (Followers: 2, SJR: 0.583, CiteScore: 1)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1, SJR: 1.095, CiteScore: 1)
Algorithmica     Hybrid Journal   (Followers: 9, SJR: 0.56, CiteScore: 1)
Allergo J.     Full-text available via subscription   (Followers: 1, SJR: 0.234, CiteScore: 0)
Allergo J. Intl.     Hybrid Journal   (Followers: 2)
Alpine Botany     Hybrid Journal   (Followers: 6, SJR: 1.11, CiteScore: 3)
ALTEX : Alternatives to Animal Experimentation     Open Access   (Followers: 2)
AMBIO     Hybrid Journal   (Followers: 10, SJR: 1.569, CiteScore: 4)
American J. of Cardiovascular Drugs     Hybrid Journal   (Followers: 16, SJR: 0.951, CiteScore: 3)
American J. of Community Psychology     Hybrid Journal   (Followers: 29, SJR: 1.329, CiteScore: 2)
American J. of Criminal Justice     Hybrid Journal   (Followers: 9, SJR: 0.772, CiteScore: 1)
American J. of Cultural Sociology     Hybrid Journal   (Followers: 18, SJR: 0.46, CiteScore: 1)
American J. of Dance Therapy     Hybrid Journal   (Followers: 5, SJR: 0.181, CiteScore: 0)
American J. of Potato Research     Hybrid Journal   (Followers: 2, SJR: 0.611, CiteScore: 1)
American J. of Psychoanalysis     Hybrid Journal   (Followers: 22, SJR: 0.314, CiteScore: 0)
American Sociologist     Hybrid Journal   (Followers: 16, SJR: 0.35, CiteScore: 0)
Amino Acids     Hybrid Journal   (Followers: 7, SJR: 1.135, CiteScore: 3)
AMS Review     Partially Free   (Followers: 4)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 8, SJR: 0.211, CiteScore: 1)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 6, SJR: 0.536, CiteScore: 1)
Analysis in Theory and Applications     Hybrid Journal   (Followers: 1)
Analysis of Verbal Behavior     Hybrid Journal   (Followers: 6)
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 32, SJR: 0.978, CiteScore: 3)
Anatomical Science Intl.     Hybrid Journal   (Followers: 3, SJR: 0.367, CiteScore: 1)
Angewandte Schmerztherapie und Palliativmedizin     Hybrid Journal  
Angiogenesis     Hybrid Journal   (Followers: 3, SJR: 2.177, CiteScore: 5)
Animal Cognition     Hybrid Journal   (Followers: 20, SJR: 1.389, CiteScore: 3)
Annales françaises de médecine d'urgence     Hybrid Journal   (Followers: 1, SJR: 0.192, CiteScore: 0)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3, SJR: 1.097, CiteScore: 2)
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4, SJR: 0.438, CiteScore: 0)
Annali dell'Universita di Ferrara     Hybrid Journal   (SJR: 0.429, CiteScore: 0)
Annali di Matematica Pura ed Applicata     Hybrid Journal   (Followers: 1, SJR: 1.197, CiteScore: 1)
Annals of Biomedical Engineering     Hybrid Journal   (Followers: 17, SJR: 1.042, CiteScore: 3)
Annals of Combinatorics     Hybrid Journal   (Followers: 4, SJR: 0.932, CiteScore: 1)
Annals of Data Science     Hybrid Journal   (Followers: 12)
Annals of Dyslexia     Hybrid Journal   (Followers: 10, SJR: 0.85, CiteScore: 2)
Annals of Finance     Hybrid Journal   (Followers: 34, SJR: 0.579, CiteScore: 1)
Annals of Forest Science     Hybrid Journal   (Followers: 7, SJR: 0.986, CiteScore: 2)
Annals of Global Analysis and Geometry     Hybrid Journal   (Followers: 1, SJR: 1.228, CiteScore: 1)
Annals of Hematology     Hybrid Journal   (Followers: 15, SJR: 1.043, CiteScore: 2)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 12, SJR: 0.413, CiteScore: 1)
Annals of Microbiology     Hybrid Journal   (Followers: 11, SJR: 0.479, CiteScore: 2)
Annals of Nuclear Medicine     Hybrid Journal   (Followers: 5, SJR: 0.687, CiteScore: 2)
Annals of Operations Research     Hybrid Journal   (Followers: 10, SJR: 0.943, CiteScore: 2)
Annals of Ophthalmology     Hybrid Journal   (Followers: 13)
Annals of Regional Science     Hybrid Journal   (Followers: 8, SJR: 0.614, CiteScore: 1)
Annals of Software Engineering     Hybrid Journal   (Followers: 13)
Annals of Solid and Structural Mechanics     Hybrid Journal   (Followers: 9, SJR: 0.239, CiteScore: 1)
Annals of Surgical Oncology     Hybrid Journal   (Followers: 15, SJR: 1.986, CiteScore: 4)
Annals of Telecommunications     Hybrid Journal   (Followers: 9, SJR: 0.223, CiteScore: 1)
Annals of the Institute of Statistical Mathematics     Hybrid Journal   (Followers: 1, SJR: 1.495, CiteScore: 1)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5, SJR: 0.834, CiteScore: 2)
Apidologie     Hybrid Journal   (Followers: 4, SJR: 1.22, CiteScore: 3)
APOPTOSIS     Hybrid Journal   (Followers: 9, SJR: 1.424, CiteScore: 4)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2, SJR: 0.294, CiteScore: 1)
Applications of Mathematics     Hybrid Journal   (Followers: 3, SJR: 0.602, CiteScore: 1)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 44, SJR: 0.571, CiteScore: 2)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 18, SJR: 0.21, CiteScore: 1)
Applied Categorical Structures     Hybrid Journal   (Followers: 4, SJR: 0.49, CiteScore: 0)
Applied Composite Materials     Hybrid Journal   (Followers: 53, SJR: 0.58, CiteScore: 2)
Applied Entomology and Zoology     Partially Free   (Followers: 6, SJR: 0.422, CiteScore: 1)
Applied Geomatics     Hybrid Journal   (Followers: 3, SJR: 0.733, CiteScore: 3)
Applied Geophysics     Hybrid Journal   (Followers: 9, SJR: 0.488, CiteScore: 1)
Applied Intelligence     Hybrid Journal   (Followers: 15, SJR: 0.6, CiteScore: 2)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4, SJR: 0.319, CiteScore: 1)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 9, SJR: 0.886, CiteScore: 1)
Applied Mathematics - A J. of Chinese Universities     Hybrid Journal   (Followers: 1, SJR: 0.17, CiteScore: 0)
Applied Mathematics and Mechanics     Hybrid Journal   (Followers: 5, SJR: 0.461, CiteScore: 1)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 67, SJR: 1.182, CiteScore: 4)
Applied Physics A     Hybrid Journal   (Followers: 10, SJR: 0.481, CiteScore: 2)
Applied Physics B: Lasers and Optics     Hybrid Journal   (Followers: 26, SJR: 0.74, CiteScore: 2)
Applied Psychophysiology and Biofeedback     Hybrid Journal   (Followers: 8, SJR: 0.519, CiteScore: 2)
Applied Research in Quality of Life     Hybrid Journal   (Followers: 12, SJR: 0.316, CiteScore: 1)
Applied Solar Energy     Hybrid Journal   (Followers: 22, SJR: 0.225, CiteScore: 0)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 7, SJR: 0.542, CiteScore: 1)
Aquaculture Intl.     Hybrid Journal   (Followers: 26, SJR: 0.591, CiteScore: 2)
Aquarium Sciences and Conservation     Hybrid Journal   (Followers: 2)
Aquatic Ecology     Hybrid Journal   (Followers: 37, SJR: 0.656, CiteScore: 2)
Aquatic Geochemistry     Hybrid Journal   (Followers: 4, SJR: 0.591, CiteScore: 1)
Aquatic Sciences     Hybrid Journal   (Followers: 14, SJR: 1.109, CiteScore: 3)
Arabian J. for Science and Engineering     Hybrid Journal   (Followers: 5, SJR: 0.303, CiteScore: 1)
Arabian J. of Geosciences     Hybrid Journal   (Followers: 2, SJR: 0.319, CiteScore: 1)
Archaeological and Anthropological Sciences     Hybrid Journal   (Followers: 21, SJR: 1.052, CiteScore: 2)
Archaeologies     Hybrid Journal   (Followers: 12, SJR: 0.224, CiteScore: 0)
Archiv der Mathematik     Hybrid Journal   (Followers: 1, SJR: 0.725, CiteScore: 1)
Archival Science     Hybrid Journal   (Followers: 68, SJR: 0.745, CiteScore: 2)
Archive for History of Exact Sciences     Hybrid Journal   (Followers: 7, SJR: 0.186, CiteScore: 1)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 3, SJR: 0.909, CiteScore: 1)
Archive for Rational Mechanics and Analysis     Hybrid Journal   (SJR: 3.93, CiteScore: 3)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 6, SJR: 0.79, CiteScore: 2)
Archives and Museum Informatics     Hybrid Journal   (Followers: 168, SJR: 0.101, CiteScore: 0)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 6, SJR: 1.41, CiteScore: 5)
Archives of Dermatological Research     Hybrid Journal   (Followers: 7, SJR: 1.006, CiteScore: 2)
Archives of Environmental Contamination and Toxicology     Hybrid Journal   (Followers: 14, SJR: 0.773, CiteScore: 2)
Archives of Gynecology and Obstetrics     Hybrid Journal   (Followers: 17, SJR: 0.956, CiteScore: 2)
Archives of Microbiology     Hybrid Journal   (Followers: 9, SJR: 0.644, CiteScore: 2)
Archives of Orthopaedic and Trauma Surgery     Hybrid Journal   (Followers: 9, SJR: 1.146, CiteScore: 2)
Archives of Osteoporosis     Hybrid Journal   (Followers: 2, SJR: 0.71, CiteScore: 2)
Archives of Sexual Behavior     Hybrid Journal   (Followers: 10, SJR: 1.493, CiteScore: 3)
Archives of Toxicology     Hybrid Journal   (Followers: 17, SJR: 1.541, CiteScore: 5)
Archives of Virology     Hybrid Journal   (Followers: 5, SJR: 0.973, CiteScore: 2)
Archives of Women's Mental Health     Hybrid Journal   (Followers: 17, SJR: 1.274, CiteScore: 3)
Archivio di Ortopedia e Reumatologia     Hybrid Journal  
Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2, SJR: 0.946, CiteScore: 3)
ArgoSpine News & J.     Hybrid Journal  
Argumentation     Hybrid Journal   (Followers: 6, SJR: 0.349, CiteScore: 1)
Arid Ecosystems     Hybrid Journal   (Followers: 3, SJR: 0.2, CiteScore: 0)
Arkiv för Matematik     Hybrid Journal   (Followers: 1, SJR: 0.766, CiteScore: 1)
Arnold Mathematical J.     Hybrid Journal   (Followers: 1, SJR: 0.355, CiteScore: 0)
Arthropod-Plant Interactions     Hybrid Journal   (Followers: 2, SJR: 0.839, CiteScore: 2)
Arthroskopie     Hybrid Journal   (Followers: 1, SJR: 0.131, CiteScore: 0)
Artificial Intelligence and Law     Hybrid Journal   (Followers: 11, SJR: 0.937, CiteScore: 2)
Artificial Intelligence Review     Hybrid Journal   (Followers: 18, SJR: 0.833, CiteScore: 4)
Artificial Life and Robotics     Hybrid Journal   (Followers: 10, SJR: 0.226, CiteScore: 0)
Asia Europe J.     Hybrid Journal   (Followers: 4, SJR: 0.504, CiteScore: 1)
Asia Pacific Education Review     Hybrid Journal   (Followers: 12, SJR: 0.479, CiteScore: 1)
Asia Pacific J. of Management     Hybrid Journal   (Followers: 16, SJR: 1.185, CiteScore: 2)
Asia-Pacific Education Researcher     Hybrid Journal   (Followers: 13, SJR: 0.353, CiteScore: 1)
Asia-Pacific Financial Markets     Hybrid Journal   (Followers: 3, SJR: 0.187, CiteScore: 0)
Asia-Pacific J. of Atmospheric Sciences     Hybrid Journal   (Followers: 19, SJR: 0.855, CiteScore: 1)
Asian Business & Management     Hybrid Journal   (Followers: 9, SJR: 0.378, CiteScore: 1)
Asian J. of Business Ethics     Hybrid Journal   (Followers: 11)
Asian J. of Criminology     Hybrid Journal   (Followers: 7, SJR: 0.543, CiteScore: 1)
AStA Advances in Statistical Analysis     Hybrid Journal   (Followers: 4, SJR: 0.548, CiteScore: 1)
AStA Wirtschafts- und Sozialstatistisches Archiv     Hybrid Journal   (Followers: 5, SJR: 0.183, CiteScore: 0)
ästhetische dermatologie & kosmetologie     Full-text available via subscription  
Astronomy and Astrophysics Review     Hybrid Journal   (Followers: 22, SJR: 3.385, CiteScore: 5)

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Similar Journals
Journal Cover
Applied Microbiology and Biotechnology
Journal Prestige (SJR): 1.182
Citation Impact (citeScore): 4
Number of Followers: 67  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1432-0614 - ISSN (Online) 0175-7598
Published by Springer-Verlag Homepage  [2351 journals]
  • Correction to: Cascade biocatalysis systems for bioactive naringenin
           glucosides and quercetin rhamnoside production from sucrose
    • Abstract: The name of the author “Yamaguchi Tokutaro” is incorrect for the first and last name has been interchanged. The correct presentation is “Tokutaro Yamaguchi”.
      PubDate: 2019-10-01
  • Advances in research on Cordyceps militaris degeneration
    • Abstract: Abstract As a highly valued fungus, Cordyceps militaris has been widely used all over the world. Although the wild resources of C. militaris are limited, the fruiting bodies of C. militaris have been successfully cultivated on a large-scale. However, the high-frequency degeneration of C. militaris during subculture and preservation seriously limits the development of the C. militaris industry. How to solve the degeneration of C. militaris has become an unsolved bottleneck problem throughout the whole Cordyceps industry. The aim of this review is to illustrate the phenotypic changes after the degeneration of C. militaris, focusing on the causes (including environmental factors and genetic variation) of C. militaris degeneration. Moreover, genetic variation is the root cause of the degeneration of C. militaris strains. Measures to prevent the degeneration of C. militaris are also discussed in this review. This paper will increase understanding of the degeneration mechanism of C. militaris, provide a reference for solving the degeneration problem of C. militaris, and lay a foundation for promoting the sustainable development of C. militaris.
      PubDate: 2019-10-01
  • β- N -Acetylhexosaminidases—the wizards of glycosylation
    • Abstract: Abstract β-N-Acetylhexosaminidases (EC are a unique family of glycoside hydrolases with dual substrate specificity and a particular reaction mechanism. Though hydrolytic enzymes per se, their good stability, easy recombinant production, absolute stereoselectivity, and a broad substrate specificity predestine these enzymes for challenging applications in carbohydrate synthesis. This mini-review aims to demonstrate the catalytic potential of β-N-acetylhexosaminidases in a range of unusual reactions, processing of unnatural substrates, formation of unexpected products, and demanding reaction designs. The use of unconventional media can considerably alter the progress of transglycosylation reactions. By means of site-directed mutagenesis, novel catalytic machineries can be constructed. Glycosylation of difficult substrates such as sugar nucleotides was accomplished, and the range of afforded glycosidic bonds comprises unique non-reducing sugars. Specific functional groups may be tolerated in the substrate molecule, which makes β-N-acetylhexosaminidases invaluable allies in difficult synthetic problems.
      PubDate: 2019-10-01
  • Acidithiobacillus thiooxidans and its potential application
    • Abstract: Abstract Acidithiobacillus thiooxidans (A. thiooxidans) is a widespread, mesophilic, obligately aerobic, extremely acidophilic, rod-shaped, and chemolithoautotrophic gram-negative gammaproteobacterium. It can obtain energy and electrons from the oxidation of reducible sulfur, and it can fix carbon dioxide and assimilate nitrate, nitrite, and ammonium to satisfy carbon and nitrogen requirement. This bacterium exists as different genomovars and its genome size range from 3.02 to 3.97 Mb. Here, we highlight the recent advances in the understanding of the general biological features of A. thiooxidans, as well as the genetic diversity and the sulfur oxidation pathway system. Additionally, the potential applications of A. thiooxidans were summarized including the recycling of metals from metal-bearing ores, electric wastes, and sludge, the improvement of alkali-salinity soils, and the removal of sulfur from sulfur-containing solids and gases.
      PubDate: 2019-10-01
  • Rapid assessment of viral water quality using a novel recombinase
           polymerase amplification test for human adenovirus
    • Abstract: Abstract Sensitive and rapid methods for determining viral contamination of water are critical, since illness can be caused by low numbers of viruses and bacterial indicators do not adequately predict viral loads. We developed novel rapid assays for detecting the viral water quality indicator human adenovirus (HAdV). A simple 15-min recombinase polymerase amplification step followed by a 5-min lateral flow detection is used. Species-specific assays were developed to discriminate HAdV A, B, C and F, and combined into a multiplex test (Ad-FAC). Species-specific assays enabled detection of 10–50 copies of the HAdV plasmid. Sample testing using methods optimised for wastewater analysis indicated the Ad-FAC assay showed 100% sensitivity and 100% specificity when compared with HAdV qPCR, with a detection limit as low as 50 gene copies. This is the first study to demonstrate the use of RPA for detecting enteric viruses in water samples, to assess virological water quality. The ability to rapidly detect enteric virus contamination of water could assist in more effective management of water safety and better protection of public health.
      PubDate: 2019-10-01
  • Cascade biocatalysis systems for bioactive naringenin glucosides and
           quercetin rhamnoside production from sucrose
    • Abstract: Abstract Two sustainable and cost-effective cascade enzymatic systems were developed to regenerate uridine diphosphate (UDP)-α-d-glucose and UDP-β-l-rhamnose from sucrose. The systems were coupled with the UDP generating glycosylation reactions of UDP sugar–dependent glycosyltransferase (UGT) enzymes mediated reactions. As a result, the UDP generated as a by-product of the GT-mediated reactions was recycled. In the first system, YjiC, a UGT from Bacillus licheniformis DSM 13, was used for transferring glucose from UDP-α-d-glucose to naringenin, in which AtSUS1 from Arabidopsis thaliana was used to synthesize UDP-α-d-glucose and fructose as a by-product from sucrose. In the second system, flavonol 7-O-rhamnosyltransferase (AtUGT89C1) from A. thaliana was used to transfer rhamnose from UDP-β-l-rhamnose to quercetin, in which AtSUS1 along with UDP-β-l-rhamnose synthase (AtRHM1), also from A. thaliana, were used to produce UDP-β-l-rhamnose from the same starter sucrose. The established UDP recycling system for the production of naringenin glucosides was engineered and optimized for several reaction parameters that included temperature, metal ions, NDPs, pH, substrate ratio, and enzymes ratio, to develop a highly feasible system for large-scale production of different derivatives of naringenin and other natural products glucosides, using inexpensive starting materials. The developed system showed the conversion of about 37 mM of naringenin into three different glucosides, namely naringenin, 7-O-β-d-glucoside, naringenin, 4′-O-β-d-glucoside, and naringenin, 4′,7-O-β-d-diglucoside. The UDP recycling (RCmax) was 20.10 for naringenin glucosides. Similarly, the conversion of quercetin to quercetin 7-O-α-l-rhamnoside reached a RCmax value of 10.0.
      PubDate: 2019-10-01
  • An overview of levan-degrading enzyme from microbes
    • Abstract: Abstract Functional carbohydrates are ideal substitutes for table sugar and make up a large share of the worldwide functional food market because of their numerous physiological benefits. Growing attention has been focused on levan, a β-(2,6) fructan that possesses more favorable physicochemical properties, such as lower intrinsic viscosity and greater colloidal stability, than β-(2,1) inulin. Levan can be used not only as a functional carbohydrate but also as feedstock for the production of levan-type fructooligosaccharides (L-FOSs). Three types of levan-degrading enzymes (LDEs), including levanase (EC, β-(2,6)-fructan 6-levanbiohydrolase (LF2ase, EC, and levan fructotransferase (LFTase, EC, play significant roles in the biological production of L-FOSs. These three enzymes convert levan into different L-FOSs, levanbiose, and difructose anhydride IV (DFA IV), respectively. The prebiotic properties of both L-FOSs and DFA IV have been confirmed in recent years. Although levanase, LF2ase, and LFTase belong to the same O-glycoside hydrolase 32 family (GH32), their catalytic properties and product spectra differ significantly. In this paper, recent studies on these LDEs are reviewed, including those investigating microbial source and catalytic properties. Additionally, comparisons of LDEs, including those of their differing cleavage behavior and applications for different L-FOSs, are presented in detail.
      PubDate: 2019-10-01
  • Categories and biomanufacturing methods of glucosamine
    • Abstract: Abstract Glucosamine (GlcN) is an amine sugar, in which a hydroxyl group of glucose is replaced with an amino group. It is an important part of the polysaccharides chitin and chitosan and is highly hydrophilic. It is also an important compound required for the formation of cartilage cells and represents one of the elementary units of the cartilage matrix and joint fluid. GlcN has been widely used in food, cosmetics, health care, and pharmaceutical industries. This paper fully addresses the categories and biomanufacturing methods of GlcN, including its production by fermentation with wild-type as well as engineered microorganisms and enzymatic catalysis with a series of chitinolytic enzymes. However, GlcN is usually produced from glucose by fermentation in a coupled manner with N-acetylglucosamine (GlcNAc). Enzymatic catalysis is thus a specific pathway for production of GlcN where chitin can be directly hydrolyzed to GlcN. In industry, GlcN produced with fungal mycelium as raw materials (plant GlcN) is thought as a high-end product because of vegetarian and non-transgenosis. In our opinion, more studies should be performed in order to develop a competitive enzymatic pathway using Aspergillus niger mycelium for the preparation of high-end GlcN.
      PubDate: 2019-10-01
  • Clonal variations in CHO IGF signaling investigated by SILAC-based
           phosphoproteomics and LFQ-MS
    • Abstract: Abstract Chinese hamster ovary (CHO) cells are commonly used for the production of monoclonal antibodies. Omics technologies have been used to elucidate cellular switch points which result in higher monoclonal antibody (mAb) productivity and process yields in CHO and other biopharmaceutical production cell lines such as human or mouse. Currently, investigations of the phosphoproteome in CHO cell lines are rare yet could provide further insights into cellular mechanisms related to target product expression. Therefore, we investigated CHO IGF–signaling events using a comparative expression and phosphoproteomic approach in recombinant mAb-producing XL99 cell lines and corresponding parental strain. Differences were found on the level of protein expression between producer and parental cells in the exponential growth phase, mainly in proteins related to the lysosome, oligosaccharide metabolic processes, stress response, and cellular homeostasis. Within a stable isotope labeling by amino acids in cell culture (SILAC)–based phosphoproteomic investigation of IGF signaling, expected general regulation of phosphorylation sites and cell line–specific responses were observed. Detected early phosphorylation events can be associated to observed effects of IGF on cellular growth, metabolism, and cell cycle distribution. Producer cell line–specific signaling exhibited differences to parental cells in intracellular trafficking and transcriptional processes, along with an overall lower amount of observable cross talk to other signaling pathways. By combining label-free and SILAC-based expression for phosphoproteomic analyses, cellular differences in the highly interactive levels of signaling and protein expression were detected, indicating alterations in metabolism and growth following treatment with an exogenous growth factor. The characterization of cell lines and effects of IGF addition resulted in identification of metabolic switch points. With this data, it will be possible to modulate pathways towards increased CHO process yield by targeted application of small-molecule inhibitors.
      PubDate: 2019-10-01
  • Enzymatic rhamnosylation of anticancer drugs by an α- l -rhamnosidase
           from Alternaria sp. L1 for cancer-targeting and enzyme-activated prodrug
    • Abstract: Abstract The synthesis of rhamnosylated compounds has gained great importance since these compounds have potential therapeutic applications. The enzymatic approaches for glycosylation of bioactive molecules have been well developed; however, the enzymatic rhamnosylation has been largely hindered by lacking of the glycosyl donor for rhamnosyltransferases. Here, we employed an α-l-rhamnosidase from Alternaria sp. L1 (RhaL1) to perform one-step rhamnosylation of anticancer drugs, including 2′-deoxy-5-fluorouridine (FUDR), cytosine arabinoside (Ara C), and hydroxyurea (Hydrea). The key synthesis conditions including substrate concentrations and reaction time were carefully optimized, and the maximum yields of each rhamnosylated drugs were 57.7 mmol for rhamnosylated Ara C, 68.6 mmol for rhamnosylated Hydrea, and 42.2 mmol for rhamnosylated FUDR. It is worth pointing out that these rhamnosylated drugs exhibit little cytotoxic effects on cancer cells, but could efficiently restore cytotoxic activity when incubated with exogenous α-l-rhamnosidase, suggesting their potential applications in the enzyme-activated prodrug system. To evaluate the cancer-targeting ability of rhamnose moiety, the rhamnose-conjugated fluorescence dye rhodamine B (Rha-RhB) was constructed. The fluorescence probe Rha-RhB displayed much higher cell affinity and cellular internalization rate of oral cancer cell KB and breast cancer cell MDA-MB-231 than that of the normal epithelial cells MCF 10A, suggesting that the rhamnose moiety could mediate the specific internalization of rhamnosylated compounds into cancer cells, which greatly facilitated their applications for cancer-targeting drug delivery.
      PubDate: 2019-10-01
  • Changes of porcine gut microbiota in response to dietary chlorogenic acid
    • Abstract: Abstract Chlorogenic acids (CGA), the most abundant natural polyphenol present in human diet and plants, have attracted considerable research interest because of their broad bioactivities including the antimicrobial activity. However, little is known about their influences on intestinal bacterial communities. Here, we described a response in intestinal microbiome to CGA using a porcine model. Twenty-four weaned pigs were allotted to two groups and fed with a basal diet or a basal diet containing 1000 mg/kg CGA. Results showed that CGA significantly increased the length of the small intestine (P < 0.05) and enhanced the activity of diamine oxidase (DAO) and the concentration of MHC-II in the jejunal and ileal mucosa (P < 0.05). Moreover, the acetate concentration in ileum and cecum digesta, and the propionate and butyrate concentrations in the cecum digesta, were significantly elevated by CGA (P < 0.05). Interestingly, CGA significantly increased the total 16S rRNA gene copies and bacterial alpha diversity in the cecum (P < 0.05). The relative abundance of bacteria from phyla Firmicutes and Bacteroidetes was increased in the cecum digesta (P < 0.05), whereas the abundance of bacteria from phylum Protebacteria was decreased by CGA (P < 0.05). Importantly, pigs on CGA-containing diet had higher abundance of Lactobacillus spp., Prevotella spp., Anaerovibrio spp., and Alloprevotella spp. in the cecum (P < 0.05). Not only did our study suggest a synergic response of intestinal barrier function and microbiota to the CGA, but the result will also contribute to understanding of the mechanisms behind the CGA-modulated gut health.
      PubDate: 2019-10-01
  • Multiplex flow cytometry serology to diagnosis of canine visceral
    • Abstract: Abstract An accurate diagnosis of visceral leishmaniasis is an essential tool for control of the disease. While serologic methods are very useful, these conventional methodologies still present limitations in terms of sensitivity and specificity. The use of flow cytometry is a worldwide trend in the development of high-performance diagnostic methods. Herein, we describe a new flow cytometry serology test, characterized by the employment of the Cytometric Bead Array microspheres A4 and E4 coated with the recombinant antigens rLci1A and rLci2B respectively, to improve the serodiagnosis of canine visceral leishmaniasis. The tests were conducted in a wide variety of sera groups (n = 140), where the diagnostics development would be optimized accounting not just the ability to identify infected dogs with different clinical status, but also to exclude cross-reaction and differentiate vaccinated dogs from dogs infected. Serological testing of the antigenic system A4–rLci1A showed a sensitivity of 90.0% and specificity of 75%, while the E4–rLci2B testing demonstrated a sensitivity of 95.0% and specificity of 82.5%. The use of a multiplex assay of A4–rLci1A and E4–rLci2B, resulted in a diagnostic improvement, with a sensitivity of 95.0% and specificity of 91.2%. Our results show that this novel flow cytometry serology test is a viable tool for sensitive and specific serodiagnosis. Notably, the combination of distinct antigenic systems allows us to test for antibodies to multiple recombinant antigens from a single serum sample. This benefit emphasizes the importance of this methodology as an alternative in the serological diagnosis.
      PubDate: 2019-10-01
  • Effects of multi-temperature regimes on cultivation of microalgae in
           municipal wastewater to simultaneously remove nutrients and produce
    • Abstract: Abstract Coupling algal cultivation with wastewater treatment due to their potentials to alleviate energy crisis and reduce environmental burden has attracted the increased attention in recent years. However, these microalgal-based processes are challenging since daily and seasonal temperature fluctuation may affect microalgal growth in wastewater, and the effects of the temperature regimes on microalgal biomass production and wastewater nutrient removal remain unclear. In this study, Chlorella vulgaris was continuously cultured for 15 days in municipal wastewater to investigate the effects on the algal biomass and wastewater nutrient removal in three temperature regimes: (1) low temperature (4 °C), (2) high temperature (35 °C), and (3) alternating high-low temperature (35 °C in the day: 4 °C at night). Compared with the other two temperature regimes, the high-low temperature conditions generated the most biomass (1.62 g L-1), the highest biomass production rate (99.21 mg L-1 day-1), and most efficient removal of COD, TN, NH3-N, and TP (83.0%, 96.5%, 97.8%, and 99.2%, respectively). In addition, the polysaccharides, proteins, lipid content, and fatty acid methyl ester composition analysis indicates that in alternating high-low temperature condition, biomass production increased the potential for biofuel production, and there was the highest lipid content (26.4% of total dry biomass). The results showed that the nutrients except COD were all efficiently removed in these temperature conditions, and the alternating high-low temperature condition showed great potential to generate algal biomass and alleviate the wastewater nutrients. This study provides some valuable information for large-scale algal cultivation in wastewater and microalgal-based wastewater treatments.
      PubDate: 2019-10-01
  • A cytochrome P450 monooxygenase gene required for biosynthesis of the
           trichothecene toxin harzianum A in Trichoderma
    • Abstract: Abstract Trichothecenes are sesquiterpene toxins produced by diverse fungi, including some species of Trichoderma that are potential plant disease biocontrol agents. Trichoderma arundinaceum produces the trichothecene harzianum A (HA), which consists of the core trichothecene structure (12,13-epoxytrichothec-9-ene, EPT) with a linear polyketide-derived substituent (octa-2,4,6-trienedioyl) esterified to an oxygen at carbon atom 4. The genes required for biosynthesis of EPT and the eight-carbon polyketide precursor of the octa-2,4,6-trienedioyl substituent, as well as for esterification of the substituent to EPT have been described. However, genes required for conversion of the polyketide (octa-2,4,6-trienoic acid) to octa-2,4,6-trienedioyl-CoA, the immediate precursor of the substituent, have not been described. Here, we identified 91 cytochrome P450 monooxygenase genes in the genome sequence of T. arundinaceum, and provided evidence from gene deletion, complementation, cross-culture feeding, and chemical analyses that one of them (tri23) is required for conversion of octa-2,4,6-trienoic acid to octa-2,4,6-trienedioyl-CoA. The gene was detected in other HA-producing Trichoderma species, but not in species of other fungal genera that produce trichothecenes with an octa-2,4,6-trienoic acid-derived substituent. These findings indicate that tri23 is a trichothecene biosynthetic gene unique to Trichoderma species, which in turn suggests that modification of octa-2,4,6-trienoic acid during trichothecene biosynthesis has evolved independently in some fungi.
      PubDate: 2019-10-01
  • Diversity of potentially exploitable pharmacological activities of the
           highly prized edible medicinal fungus Antrodia camphorata
    • Abstract: Abstract Antrodia camphorata, also known as A. cinnamomea, is a precious medicinal basidiomycete fungus endemic to Taiwan. This article summarizes the recent advances in research on the multifarious pharmacological effects of A. camphorata. The mushroom exhibits anticancer activity toward a large variety of cancers including breast, cervical, ovarian, prostate, bladder, colorectal, pancreatic, liver, and lung cancers; melanoma; leukemia; lymphoma; neuroblastoma; and glioblastoma. Other activities encompass antiinflammatory, antiatopic dermatitis, anticachexia, immunoregulatory, antiobesity, antidiabetic, antihyperlipidemic, antiatherosclerotic, antihypertensive, antiplatelet, antioxidative, antiphotodamaging, hepatoprotective, renoprotective, neuroprotective, testis protecting, antiasthmatic, osteogenic, osteoprotective, antiviral, antibacterial, and wound healing activities. This review aims to provide a reference for further development and utilization of this highly prized mushroom.
      PubDate: 2019-10-01
  • Development of a Cre- lox P-based genetic system in Aspergillus niger
           ATCC1015 and its application to construction of efficient organic
           acid-producing cell factories
    • Abstract: Abstract The filamentous fungus Aspergillus niger is widely used in the biotechnology industry for the production of chemicals and enzymes. Engineering of this valuable organism to improve its productivity is currently hampered by the lack of efficient genetic tools. Here, a Cre-loxP-based system for gene editing in A. niger was developed and its application in construction of A. niger cell factories to produce various organic acids was explored. Two established inducible systems, the xylanase A gene promoter Pxln and Tet-on system, were examined for driving cre expression and thus selection marker hyh deletion. Under inducing conditions, the efficiency of loxP site-specific recombination in the strain with cre driven by Pxln is about 2%, while cre driven by Tet-on system is about 34% which was used as the platform strain for further genetic engineering. As a proof of application of this system, strains containing different copies of oxaloacetate acetylhydrolase–encoding gene (oahA) were constructed, and the resultant strain S428 showed as high as 3.1-fold increase in oxalic acid production. Furthermore, an efficient malate-producing strain was generated through four-step genetic manipulation (oahA deletion, pyc, mdh3 and C4-dicarboxylate transporter gene c4t318 insertion). The resultant strain S575 achieved a titer 120.38 g/L malic acid with the flask culture, and a titer 201.24 g/L malic acid in fed-batch fermentation. These results demonstrated that this modified Cre-loxP system is a powerful tool for genetic engineering in A. niger, which has the potential to be genetically modified as a viable aciduric platform strain to produce high levels of various organic acids.
      PubDate: 2019-10-01
  • Biochemical and structural characterization of a highly active
           branched-chain amino acid aminotransferase from Pseudomonas sp. for
           efficient biosynthesis of chiral amino acids
    • Abstract: Abstract Aminotransferases (ATs) are important biocatalysts for the synthesis of chiral amines because of their capability of introducing amino group into ketones or keto acids as well as their high enantioselectivity, high regioselectivity. Among all ATs, branched-chain amino acid aminotransferase (BCAT) can use branched-chain amino acids (BCAAs) as substrate, including L-valine, L-leucine, and L-isoleucine, with α-ketoglutarate to form the corresponding α-keto acids and L-glutamate. Alternatively, BCATs have been used for the biosynthesis of unnatural amino acids, such as L-tert-leucine and L-norvaline. In the present study, the BCAT from Pseudomonas sp. (PsBCAT) was cloned and expressed in Escherichia coli for biochemical and structural analyses. The optimal reaction temperature and pH of PsBCAT were 40 °C and 8.5, respectively. PsBCAT exhibited a comparatively broader substrate spectrum and showed remarkably high activity with bulked aliphatic L-amino acids (kcat up to 220 s−1). Additionally, PsBCAT had activities with aromatic L-amino acids, L-histidine, L-lysine, and L-threonine. This substrate promiscuity is unique for the BCAT family and could prove useful in industrial applications. To analyze the catalytic mechanism of PsBCAT with the broad substrate spectrum, the crystal structure of PsBCAT was also determined. Based on the determined crystal structure, we found some differences in the organization of the substrate binding cavity, which may influence the substrate specificity of the enzyme. Finally, conjugated with the ornithine aminotransferase (OrnAT) to shift the reaction equilibrium towards the product formation, the coupled system was applied to the asymmetric synthesis of L-tert-leucine and L-norvaline. In summary, the structural and functional characteristics of PsBCAT were analyzed in detail, and this information will be conducive to industrial production of enantiopure chiral amino acids by aminotransferase.
      PubDate: 2019-09-04
  • Comprehensive genomic and transcriptomic analysis of polycyclic aromatic
           hydrocarbon degradation by a mycoremediation fungus, Dentipellis sp.
    • Abstract: Abstract The environmental accumulation of polycyclic aromatic hydrocarbons (PAHs) is of great concern due to potential carcinogenic and mutagenic risks, as well as their resistance to remediation. While many fungi have been reported to break down PAHs in environments, the details of gene-based metabolic pathways are not yet comprehensively understood. Specifically, the genome-scale transcriptional responses of fungal PAH degradation have rarely been reported. In this study, we report the genomic and transcriptomic basis of PAH bioremediation by a potent fungal degrader, Dentipellis sp. KUC8613. The genome size of this fungus was 36.71 Mbp long encoding 14,320 putative protein-coding genes. The strain efficiently removed more than 90% of 100 mg/l concentration of PAHs within 10 days. The genomic and transcriptomic analysis of this white rot fungus highlights that the strain primarily utilized non-ligninolytic enzymes to remove various PAHs, rather than typical ligninolytic enzymes known for playing important roles in PAH degradation. PAH removal by non-ligninolytic enzymes was initiated by both different PAH-specific and common upregulation of P450s, followed by downstream PAH-transforming enzymes such as epoxide hydrolases, dehydrogenases, FAD-dependent monooxygenases, dioxygenases, and glycosyl- or glutathione transferases. Among the various PAHs, phenanthrene induced a more dynamic transcriptomic response possibly due to its greater cytotoxicity, leading to highly upregulated genes involved in the translocation of PAHs, a defense system against reactive oxygen species, and ATP synthesis. Our genomic and transcriptomic data provide a foundation of understanding regarding the mycoremediation of PAHs and the application of this strain for polluted environments.
      PubDate: 2019-09-03
  • Enriched hydrogen-oxidizing microbiomes show a high diversity of
           co-existing hydrogen-oxidizing bacteria
    • Abstract: Abstract While numerous reports exist on the axenic culturing of different hydrogen-oxidizing bacteria (HOB), knowledge about the enrichment of microbial communities growing on hydrogen, oxygen, and carbon dioxide as sole carbon and energy sources remains negligible. We want to elucidate if in such enrichments, most enriched populations are HOBs or heterotrophic organisms. In the present study, bacteria enriched from a soil sample and grown over 5 transfers using a continuous supply of hydrogen, oxygen, and carbon dioxide to obtain an enriched autotrophic hydrogen-oxidizing microbiome. The success of the enrichment was evaluated by monitoring ammonium consumption and biomass concentration for 120 days. The shift in the microbial composition of the original soil inoculum and all transfers was observed based on 16S rRNA amplicon sequencing. The hydrogen-oxidizing facultative chemolithoautotroph Hydrogenophaga electricum was isolated and found to be one of the abundant species in most transfers. Moreover, Achromobacter was isolated both under heterotrophic and autotrophic conditions, which was characterized as a hydrogen-oxidizing bacterium. The HOB enrichment condition constructed in this study provided an environment for HOB to develop and conquer in all transfers. In conclusion, we showed that enrichments on hydrogen, oxygen, and carbon dioxide as sole carbon and energy sources contain a diverse mixture of HOB and heterotrophs that resulted in a collection of culturable isolates. These isolates can be useful for further investigation for industrial applications.
      PubDate: 2019-09-03
  • Discovering a novel d -xylonate-responsive promoter: the P yjhI -driven
           genetic switch towards better 1,2,4-butanetriol production
    • Abstract: Abstract The capability of Escherichia coli to catabolize d-xylonate is a crucial component for building and optimizing the Dahms pathway. It relies on the inherent dehydratase and keto-acid aldolase activities of E. coli. Although the biochemical characteristics of these enzymes are known, their inherent expression regulation remains unclear. This knowledge is vital for the optimization of d-xylonate assimilation, especially in addressing the problem of d-xylonate accumulation, which hampers both cell growth and target product formation. In this report, molecular biology techniques and synthetic biology tools were combined to build a simple genetic switch controller for d-xylonate. First, quantitative and relative expression analysis of the gene clusters involved in d-xylonate catabolism were performed, revealing two d-xylonate-inducible operons, yagEF and yjhIHG. The 5′-flanking DNA sequence of these operons were then subjected to reporter gene assays which showed PyjhI to have low background activity and wide response range to d-xylonate. A PyjhI-driven synthetic genetic switch was then constructed containing feedback control to autoregulate d-xylonate accumulation and to activate the expression of the genes for 1,2,4-butanetriol (BTO) production. The genetic switch effectively reduced d-xylonate accumulation, which led to 31% BTO molar yield, the highest for direct microbial fermentation systems thus far. This genetic switch can be further modified and employed in the production of other compounds from d-xylose through the xylose oxidative pathway.
      PubDate: 2019-09-03
School of Mathematical and Computer Sciences
Heriot-Watt University
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