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Publisher: Springer-Verlag (Total: 2353 journals)

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Showing 1 - 200 of 2353 Journals sorted alphabetically
3D Research     Hybrid Journal   (Followers: 19, SJR: 0.214, h-index: 10)
4OR: A Quarterly J. of Operations Research     Hybrid Journal   (Followers: 9, SJR: 1.073, h-index: 25)
AAPS J.     Hybrid Journal   (Followers: 20, SJR: 1.192, h-index: 74)
AAPS PharmSciTech     Hybrid Journal   (Followers: 6, SJR: 0.718, h-index: 54)
Abdominal Imaging     Hybrid Journal   (Followers: 14, SJR: 0.723, h-index: 60)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 3, SJR: 0.447, h-index: 12)
Academic Psychiatry     Full-text available via subscription   (Followers: 22, SJR: 0.492, h-index: 32)
Academic Questions     Hybrid Journal   (Followers: 7, SJR: 0.135, h-index: 6)
Accreditation and Quality Assurance: J. for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26, SJR: 0.378, h-index: 30)
Acoustical Physics     Hybrid Journal   (Followers: 11, SJR: 0.355, h-index: 20)
Acoustics Australia     Hybrid Journal  
Acta Analytica     Hybrid Journal   (Followers: 7, SJR: 0.387, h-index: 6)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1, SJR: 0.624, h-index: 34)
Acta Biotheoretica     Hybrid Journal   (Followers: 5, SJR: 0.419, h-index: 25)
Acta Diabetologica     Hybrid Journal   (Followers: 14, SJR: 1.318, h-index: 46)
Acta Endoscopica     Hybrid Journal   (Followers: 1, SJR: 0.113, h-index: 8)
acta ethologica     Hybrid Journal   (Followers: 4, SJR: 0.465, h-index: 23)
Acta Geochimica     Hybrid Journal   (Followers: 4)
Acta Geodaetica et Geophysica     Hybrid Journal   (Followers: 1, SJR: 0.294, h-index: 13)
Acta Geotechnica     Hybrid Journal   (Followers: 7, SJR: 1.818, h-index: 22)
Acta Informatica     Hybrid Journal   (Followers: 5, SJR: 0.524, h-index: 32)
Acta Mathematica     Hybrid Journal   (Followers: 11, SJR: 8.021, h-index: 47)
Acta Mathematica Hungarica     Hybrid Journal   (Followers: 2, SJR: 0.53, h-index: 29)
Acta Mathematica Sinica, English Series     Hybrid Journal   (Followers: 5, SJR: 0.406, h-index: 30)
Acta Mathematica Vietnamica     Hybrid Journal   (SJR: 0.451, h-index: 5)
Acta Mathematicae Applicatae Sinica, English Series     Hybrid Journal   (SJR: 0.22, h-index: 20)
Acta Mechanica     Hybrid Journal   (Followers: 19, SJR: 0.898, h-index: 52)
Acta Mechanica Sinica     Hybrid Journal   (Followers: 5, SJR: 0.426, h-index: 29)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5, SJR: 0.525, h-index: 18)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.524, h-index: 14)
Acta Neurochirurgica     Hybrid Journal   (Followers: 6, SJR: 0.833, h-index: 73)
Acta Neurologica Belgica     Hybrid Journal   (SJR: 0.348, h-index: 27)
Acta Neuropathologica     Hybrid Journal   (Followers: 5, SJR: 6.61, h-index: 117)
Acta Oceanologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.295, h-index: 17)
Acta Parasitologica     Hybrid Journal   (Followers: 9, SJR: 0.581, h-index: 28)
Acta Physiologiae Plantarum     Hybrid Journal   (Followers: 2, SJR: 0.551, h-index: 39)
Acta Politica     Hybrid Journal   (Followers: 13, SJR: 0.658, h-index: 20)
Activitas Nervosa Superior     Hybrid Journal  
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5, SJR: 0.103, h-index: 4)
ADHD Attention Deficit and Hyperactivity Disorders     Hybrid Journal   (Followers: 21, SJR: 0.871, h-index: 15)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 7)
Administration and Policy in Mental Health and Mental Health Services Research     Partially Free   (Followers: 15, SJR: 0.795, h-index: 40)
Adsorption     Hybrid Journal   (Followers: 4, SJR: 0.774, h-index: 52)
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 3, SJR: 0.319, h-index: 15)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 34, SJR: 0.959, h-index: 44)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 15, SJR: 1.255, h-index: 44)
Advances in Contraception     Hybrid Journal   (Followers: 3)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 53, SJR: 1.113, h-index: 14)
Advances in Gerontology     Partially Free   (Followers: 9, SJR: 0.141, h-index: 3)
Advances in Health Sciences Education     Hybrid Journal   (Followers: 22, SJR: 1.397, h-index: 42)
Advances in Manufacturing     Hybrid Journal   (Followers: 3, SJR: 0.2, h-index: 4)
Advances in Polymer Science     Hybrid Journal   (Followers: 41, SJR: 0.637, h-index: 89)
Advances in Therapy     Hybrid Journal   (Followers: 5, SJR: 0.79, h-index: 44)
Aegean Review of the Law of the Sea and Maritime Law     Hybrid Journal   (Followers: 7)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2, SJR: 0.882, h-index: 23)
Aerobiologia     Hybrid Journal   (Followers: 1, SJR: 0.511, h-index: 36)
Aesthetic Plastic Surgery     Hybrid Journal   (Followers: 9, SJR: 0.821, h-index: 49)
African Archaeological Review     Hybrid Journal   (Followers: 15, SJR: 0.612, h-index: 24)
Afrika Matematika     Hybrid Journal   (Followers: 1, SJR: 0.248, h-index: 6)
AGE     Hybrid Journal   (Followers: 7, SJR: 1.358, h-index: 33)
Ageing Intl.     Hybrid Journal   (Followers: 7, SJR: 0.337, h-index: 10)
Aggiornamenti CIO     Hybrid Journal   (Followers: 1)
Aging Clinical and Experimental Research     Hybrid Journal   (Followers: 3, SJR: 0.529, h-index: 55)
Agricultural Research     Hybrid Journal   (Followers: 3)
Agriculture and Human Values     Hybrid Journal   (Followers: 12, SJR: 1.197, h-index: 49)
Agroforestry Systems     Hybrid Journal   (Followers: 20, SJR: 0.64, h-index: 56)
Agronomy for Sustainable Development     Hybrid Journal   (Followers: 10, SJR: 1.732, h-index: 59)
AI & Society     Hybrid Journal   (Followers: 7, SJR: 0.171, h-index: 19)
AIDS and Behavior     Hybrid Journal   (Followers: 13, SJR: 2.006, h-index: 71)
Air Quality, Atmosphere & Health     Hybrid Journal   (Followers: 3, SJR: 0.706, h-index: 19)
Akupunktur & Aurikulomedizin     Full-text available via subscription   (Followers: 1)
Algebra and Logic     Hybrid Journal   (Followers: 4, SJR: 0.566, h-index: 18)
Algebra Universalis     Hybrid Journal   (Followers: 2, SJR: 0.388, h-index: 22)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1, SJR: 0.868, h-index: 20)
Algorithmica     Hybrid Journal   (Followers: 8, SJR: 0.898, h-index: 56)
Allergo J.     Full-text available via subscription   (Followers: 1, SJR: 0.183, h-index: 20)
Allergo J. Intl.     Hybrid Journal   (Followers: 2)
Alpine Botany     Hybrid Journal   (Followers: 4, SJR: 0.729, h-index: 20)
ALTEX : Alternatives to Animal Experimentation     Open Access   (Followers: 3, SJR: 1.392, h-index: 32)
AMBIO     Hybrid Journal   (Followers: 15, SJR: 1.094, h-index: 87)
American J. of Cardiovascular Drugs     Hybrid Journal   (Followers: 13, SJR: 0.864, h-index: 39)
American J. of Community Psychology     Hybrid Journal   (Followers: 23, SJR: 1.237, h-index: 83)
American J. of Criminal Justice     Hybrid Journal   (Followers: 6, SJR: 0.634, h-index: 13)
American J. of Cultural Sociology     Hybrid Journal   (Followers: 11, SJR: 0.283, h-index: 3)
American J. of Dance Therapy     Hybrid Journal   (Followers: 4, SJR: 0.175, h-index: 13)
American J. of Potato Research     Hybrid Journal   (Followers: 2, SJR: 0.558, h-index: 35)
American J. of Psychoanalysis     Hybrid Journal   (Followers: 21, SJR: 0.293, h-index: 13)
American Sociologist     Hybrid Journal   (Followers: 12, SJR: 0.18, h-index: 13)
Amino Acids     Hybrid Journal   (Followers: 8, SJR: 1.362, h-index: 83)
AMS Review     Partially Free   (Followers: 4)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 7, SJR: 0.21, h-index: 37)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 3, SJR: 0.665, h-index: 7)
Analysis in Theory and Applications     Hybrid Journal   (Followers: 1)
Analysis of Verbal Behavior     Hybrid Journal   (Followers: 5)
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 29, SJR: 1.096, h-index: 123)
Anatomical Science Intl.     Hybrid Journal   (Followers: 2, SJR: 0.301, h-index: 26)
Angewandte Schmerztherapie und Palliativmedizin     Hybrid Journal  
Angiogenesis     Hybrid Journal   (Followers: 3, SJR: 2.212, h-index: 69)
Animal Cognition     Hybrid Journal   (Followers: 16, SJR: 1.122, h-index: 55)
Annales françaises de médecine d'urgence     Hybrid Journal   (Followers: 1, SJR: 0.156, h-index: 4)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3, SJR: 1.377, h-index: 32)
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4)
Annali dell'Universita di Ferrara     Hybrid Journal   (SJR: 0.504, h-index: 14)
Annali di Matematica Pura ed Applicata     Hybrid Journal   (Followers: 1, SJR: 1.167, h-index: 26)
Annals of Behavioral Medicine     Hybrid Journal   (Followers: 11, SJR: 2.112, h-index: 98)
Annals of Biomedical Engineering     Hybrid Journal   (Followers: 18, SJR: 1.182, h-index: 94)
Annals of Combinatorics     Hybrid Journal   (Followers: 3, SJR: 0.849, h-index: 15)
Annals of Data Science     Hybrid Journal   (Followers: 9)
Annals of Dyslexia     Hybrid Journal   (Followers: 9, SJR: 0.857, h-index: 40)
Annals of Finance     Hybrid Journal   (Followers: 28, SJR: 0.686, h-index: 14)
Annals of Forest Science     Hybrid Journal   (Followers: 4, SJR: 0.929, h-index: 57)
Annals of Global Analysis and Geometry     Hybrid Journal   (Followers: 1, SJR: 1.136, h-index: 23)
Annals of Hematology     Hybrid Journal   (Followers: 14, SJR: 1.117, h-index: 62)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 6, SJR: 0.593, h-index: 42)
Annals of Microbiology     Hybrid Journal   (Followers: 10, SJR: 0.402, h-index: 26)
Annals of Nuclear Medicine     Hybrid Journal   (Followers: 5, SJR: 0.68, h-index: 45)
Annals of Operations Research     Hybrid Journal   (Followers: 8, SJR: 1.186, h-index: 78)
Annals of Ophthalmology     Hybrid Journal   (Followers: 11)
Annals of Regional Science     Hybrid Journal   (Followers: 7, SJR: 0.405, h-index: 42)
Annals of Software Engineering     Hybrid Journal   (Followers: 12)
Annals of Solid and Structural Mechanics     Hybrid Journal   (Followers: 10, SJR: 0.553, h-index: 8)
Annals of Surgical Oncology     Hybrid Journal   (Followers: 15, SJR: 1.902, h-index: 127)
Annals of Telecommunications     Hybrid Journal   (Followers: 7, SJR: 0.315, h-index: 25)
Annals of the Institute of Statistical Mathematics     Hybrid Journal   (Followers: 1, SJR: 0.931, h-index: 31)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5, SJR: 0.992, h-index: 87)
Apidologie     Hybrid Journal   (Followers: 4, SJR: 1.14, h-index: 57)
APOPTOSIS     Hybrid Journal   (Followers: 8, SJR: 1.554, h-index: 87)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2, SJR: 0.354, h-index: 27)
Applications of Mathematics     Hybrid Journal   (Followers: 1, SJR: 0.274, h-index: 20)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 44, SJR: 0.575, h-index: 80)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 17, SJR: 0.267, h-index: 26)
Applied Cancer Research     Open Access  
Applied Categorical Structures     Hybrid Journal   (Followers: 2, SJR: 0.361, h-index: 21)
Applied Composite Materials     Hybrid Journal   (Followers: 48, SJR: 0.705, h-index: 35)
Applied Entomology and Zoology     Partially Free   (Followers: 2, SJR: 0.554, h-index: 34)
Applied Geomatics     Hybrid Journal   (Followers: 3, SJR: 0.323, h-index: 9)
Applied Geophysics     Hybrid Journal   (Followers: 8, SJR: 0.541, h-index: 13)
Applied Intelligence     Hybrid Journal   (Followers: 11, SJR: 0.777, h-index: 43)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4, SJR: 0.358, h-index: 34)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 4, SJR: 0.955, h-index: 33)
Applied Mathematics - A J. of Chinese Universities     Hybrid Journal   (SJR: 0.275, h-index: 8)
Applied Mathematics and Mechanics     Hybrid Journal   (Followers: 4, SJR: 0.37, h-index: 26)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 62, SJR: 1.262, h-index: 161)
Applied Physics A     Hybrid Journal   (Followers: 7, SJR: 0.535, h-index: 121)
Applied Physics B: Lasers and Optics     Hybrid Journal   (Followers: 23, SJR: 0.983, h-index: 104)
Applied Psychophysiology and Biofeedback     Hybrid Journal   (Followers: 8, SJR: 0.677, h-index: 47)
Applied Research in Quality of Life     Hybrid Journal   (Followers: 10, SJR: 0.288, h-index: 15)
Applied Solar Energy     Hybrid Journal   (Followers: 17, SJR: 0.251, h-index: 6)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4, SJR: 0.351, h-index: 9)
Aquaculture Intl.     Hybrid Journal   (Followers: 22, SJR: 0.613, h-index: 40)
Aquarium Sciences and Conservation     Hybrid Journal   (Followers: 1)
Aquatic Ecology     Hybrid Journal   (Followers: 30, SJR: 0.646, h-index: 44)
Aquatic Geochemistry     Hybrid Journal   (Followers: 4, SJR: 0.764, h-index: 39)
Aquatic Sciences     Hybrid Journal   (Followers: 12, SJR: 1.172, h-index: 53)
Arabian J. for Science and Engineering     Hybrid Journal   (Followers: 5, SJR: 0.345, h-index: 20)
Arabian J. of Geosciences     Hybrid Journal   (Followers: 1, SJR: 0.417, h-index: 16)
Archaeological and Anthropological Sciences     Hybrid Journal   (Followers: 22, SJR: 1.056, h-index: 15)
Archaeologies     Hybrid Journal   (Followers: 12, SJR: 0.397, h-index: 13)
Archiv der Mathematik     Hybrid Journal   (Followers: 1, SJR: 0.597, h-index: 29)
Archival Science     Hybrid Journal   (Followers: 53, SJR: 0.804, h-index: 22)
Archive for History of Exact Sciences     Hybrid Journal   (Followers: 7, SJR: 0.28, h-index: 15)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 1, SJR: 0.946, h-index: 23)
Archive for Rational Mechanics and Analysis     Hybrid Journal   (SJR: 4.091, h-index: 66)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 5, SJR: 0.865, h-index: 40)
Archives and Museum Informatics     Hybrid Journal   (Followers: 124)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4, SJR: 2.841, h-index: 40)
Archives of Dermatological Research     Hybrid Journal   (Followers: 6, SJR: 0.9, h-index: 65)
Archives of Environmental Contamination and Toxicology     Hybrid Journal   (Followers: 9, SJR: 0.846, h-index: 84)
Archives of Gynecology and Obstetrics     Hybrid Journal   (Followers: 17, SJR: 0.695, h-index: 47)
Archives of Microbiology     Hybrid Journal   (Followers: 8, SJR: 0.702, h-index: 85)
Archives of Orthopaedic and Trauma Surgery     Hybrid Journal   (Followers: 8, SJR: 1.039, h-index: 56)
Archives of Osteoporosis     Hybrid Journal   (Followers: 2, SJR: 1.092, h-index: 13)
Archives of Sexual Behavior     Hybrid Journal   (Followers: 9, SJR: 1.198, h-index: 74)
Archives of Toxicology     Hybrid Journal   (Followers: 16, SJR: 1.595, h-index: 76)
Archives of Virology     Hybrid Journal   (Followers: 5, SJR: 1.086, h-index: 90)
Archives of Women's Mental Health     Hybrid Journal   (Followers: 14, SJR: 1.264, h-index: 50)
Archivio di Ortopedia e Reumatologia     Hybrid Journal  
Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2, SJR: 1.2, h-index: 42)
ArgoSpine News & J.     Hybrid Journal   (SJR: 0.102, h-index: 3)
Argumentation     Hybrid Journal   (Followers: 5, SJR: 0.295, h-index: 18)
Arid Ecosystems     Hybrid Journal   (Followers: 3)
Arkiv för Matematik     Hybrid Journal   (Followers: 1, SJR: 0.948, h-index: 22)
Arnold Mathematical J.     Hybrid Journal   (Followers: 1)
Arthropod-Plant Interactions     Hybrid Journal   (Followers: 1, SJR: 0.797, h-index: 17)
Arthroskopie     Hybrid Journal   (Followers: 1, SJR: 0.145, h-index: 8)
Artificial Intelligence and Law     Hybrid Journal   (Followers: 10, SJR: 0.288, h-index: 25)
Artificial Intelligence Review     Hybrid Journal   (Followers: 14, SJR: 0.948, h-index: 48)
Artificial Life and Robotics     Hybrid Journal   (Followers: 8, SJR: 0.231, h-index: 14)
Asia Europe J.     Hybrid Journal   (Followers: 4, SJR: 0.247, h-index: 9)
Asia Pacific Education Review     Hybrid Journal   (Followers: 9, SJR: 0.371, h-index: 17)
Asia Pacific J. of Management     Hybrid Journal   (Followers: 14, SJR: 1.676, h-index: 50)
Asia-Pacific Education Researcher     Hybrid Journal   (Followers: 11, SJR: 0.353, h-index: 13)
Asia-Pacific Financial Markets     Hybrid Journal   (Followers: 2, SJR: 0.19, h-index: 15)
Asia-Pacific J. of Atmospheric Sciences     Hybrid Journal   (Followers: 20, SJR: 1.006, h-index: 14)
Asian Business & Management     Hybrid Journal   (Followers: 7, SJR: 0.41, h-index: 10)
Asian J. of Business Ethics     Hybrid Journal   (Followers: 7)
Asian J. of Criminology     Hybrid Journal   (Followers: 5, SJR: 0.263, h-index: 8)
AStA Advances in Statistical Analysis     Hybrid Journal   (Followers: 2, SJR: 0.681, h-index: 15)
AStA Wirtschafts- und Sozialstatistisches Archiv     Hybrid Journal   (Followers: 5, SJR: 0.195, h-index: 5)
ästhetische dermatologie & kosmetologie     Full-text available via subscription  

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Journal Cover Applied Microbiology and Biotechnology
  [SJR: 1.262]   [H-I: 161]   [62 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1432-0614 - ISSN (Online) 0175-7598
   Published by Springer-Verlag Homepage  [2353 journals]
  • Therapeutic potentials of short interfering RNAs
    • Authors: Chit Tam; Jack Ho Wong; Randy Chi Fai Cheung; Tao Zuo; Tzi Bun Ng
      Pages: 7091 - 7111
      Abstract: Abstract Short interfering RNA (siRNA) is one of the members of the family of RNA interference (RNAi). Coupled with the RNA-induced silencing complex (RISC), siRNA is able to trigger the cleavage of target RNAs which serve as a defensive system against pathogens. Meanwhile, siRNA in gene silencing opens a new avenue for the treatment of various diseases. SiRNA can effectively inhibit viral infection and replication and suppress tumorigenesis and various inflammation-associated diseases and cardiovascular diseases by inactivation of viral genes and downregulation of oncogene expression. Recently, endogenous siRNAs (endo-siRNAs) were discovered in the reproductive cells of animals which may be associated with regulation of cell division. Structural modification of siRNA enhances the delivery, specificity and efficacy and bioavailability to the target cells. There are at least five categories of siRNA delivery systems including viral vectors, lipid-based nanoparticles, peptide-based nanoparticles, polymer-based nanoparticles and inorganic small molecules like metal ions, silica and carbon. Sufficient preclinical and clinical studies supported that siRNA may be a potential medicine for targeted therapy of various diseases in the near future.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8433-z
      Issue No: Vol. 101, No. 19 (2017)
       
  • The unusual cellulose utilization system of the aerobic soil bacterium
           Cytophaga hutchinsonii
    • Authors: Yongtao Zhu; Mark J. McBride
      Pages: 7113 - 7127
      Abstract: Abstract Cellulolytic microorganisms play important roles in global carbon cycling and have evolved diverse strategies to digest cellulose. Some are ‘generous,’ releasing soluble sugars from cellulose extracellularly to feed both themselves and their neighbors. The gliding soil bacterium Cytophaga hutchinsonii exhibits a more ‘selfish’ strategy. It digests crystalline cellulose using cell-associated cellulases and releases little soluble sugar outside of the cell. The mechanism of C. hutchinsonii cellulose utilization is still poorly understood. In this review, we discuss novel aspects of the C. hutchinsonii cellulolytic system. Recently developed genetic manipulation tools allowed the identification of proteins involved in C. hutchinsonii cellulose utilization. These include periplasmic and cell-surface endoglucanases and novel cellulose-binding proteins. The recently discovered type IX secretion system is needed for cellulose utilization and appears to deliver some of the cellulolytic enzymes and other proteins to the cell surface. The requirement for periplasmic endoglucanases for cellulose utilization is unusual and suggests that cello-oligomers must be imported across the outer membrane before being further digested. Cellobiohydrolases or other predicted processive cellulases that play important roles in many other cellulolytic bacteria appear to be absent in C. hutchinsonii. Cells of C. hutchinsonii attach to and glide along cellulose fibers, which may allow them to find sites most amenable to attack. A model of C. hutchinsonii cellulose utilization summarizing recent progress is proposed.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8467-2
      Issue No: Vol. 101, No. 19 (2017)
       
  • Biotransformation with cellulase, hemicellulase and Yarrowia lipolytica
           boosts health benefits of okara
    • Authors: Weng Chan Vong; Xin Ying Lim; Shao-Quan Liu
      Pages: 7129 - 7140
      Abstract: Abstract Okara (soybean residue) is a highly perishable food processing by-product from soymilk and tofu manufacture. It contains a large proportion of insoluble dietary fibre (40–60% on a dry basis), as well as digestion-resistant proteins, trypsin inhibitors and phytic acid. These factors contribute lead to the under-utilisation of okara. To improve the overall nutritional quality of okara, sequential saccharification of okara by Celluclast® 1.5L (cellulase) or Viscozyme® L (cellulase and hemicellulase) and fermentation by the yeast Yarrowia lipolytica were performed. The changes in the antioxidant capacity, amino acids, phenolic acids, isoflavones, phytic acid and dietary fibre during biotransformation were studied. Carbohydrase pre-treatment increased the amounts of monosaccharides, trans-cinnamic acid and aglycone isoflavones in okara. After fermentation, the okara had higher antioxidant activity and greater amounts of total amino acids and ferulic acid. Some positive interactions between the carbohydrase and Y. lipolytica were hypothesised: the carbohydrase and Y. lipolytica proteases could have synergised with each other to break down the okara secondary cell wall more efficiently. After 52 h, Celluclast® 1.5 L and Viscozyme® L significantly reduced the insoluble dietary fibre content from 61.9 ± 0.6 to 45.6 ± 3.0% and 24.7 ± 0.3%, respectively (all w/w, dry basis), while increasing the soluble dietary fibre content by about onefold. Both carbohydrases also increased the amounts of monosaccharides, trans-cinnamic acid, and aglycone isoflavones in okara. The addition of Y. lipolytica led to a higher antioxidant capacity and greater amounts of total amino acids and ferulic acid in okara. The overall improvements in the digestibility and potential health benefits of okara highlight the promising applicability of biotransformation in okara valorisation.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8431-1
      Issue No: Vol. 101, No. 19 (2017)
       
  • Lactococcus lactis as a safe and inexpensive source of bioactive silver
           composites
    • Authors: Railean-Plugaru Viorica; Pomastowski Pawel; Meller Kinga; Złoch Michal; Rafinska Katarzyna; Buszewski Boguslaw
      Pages: 7141 - 7153
      Abstract: Abstract This research develops a safe, inexpensive, and more accessible source for synthesis of silver nanoparticles. The bioactive silver composites synthesized by Lactococcus lactis 56 KY484989 (LCLB56-AgCs) were characterized by various physico-chemical techniques and investigated for their antimicrobial activity and cytotoxicity. The average amount of nanoparticles was 0.363 ± 0.09 mg from 50 mL of culture medium. The synthesis efficiency varied from 71 to 85%. Synthesized silver nanoparticles with spherical in shape were found to be of 5–50 nm and average diameter 19 ± 2 nm. Based on the shape of isotopic pattern of d-electrons metals, the signals of silver isotopes [107Ag]+ at m/z 106.905 and [109Ag]+ at m/z 108.910 were confirmed. Moreover, LCLB56-AgCs exerted an inhibitory effect against all tested bacterial strains (Pseudomonas aeruginosa ATCC10145, Proteus mirabilis ATCC25933, Staphylococcus epidermidis ATCC49461, MSSA ATCC29213, and Staphylococcus aureus ATCC6338). More pronounced antimicrobial effect was noticed for 15 μg/well. Minimum inhibitory concentration required to inhibite the growth of 90% organism (MIC90) of synthetized LCLB56-AgCs was in a range of 3.125–12.5 μg/mL. The concentration at which the viability of the L929 cells was reduced to 50% was above 200 μg/mL for LCLB56-AgNCs. These results open up possibilities for many applications of bioactive silver composites (BioAgCs) synthesized by L. lactis 56 in food and pharmaceutical industries.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8443-x
      Issue No: Vol. 101, No. 19 (2017)
       
  • Improvement of glycerol catabolism in Bacillus licheniformis for
           production of poly-γ-glutamic acid
    • Authors: Yangyang Zhan; Chengjun Zhu; Bojie Sheng; Dongbo Cai; Qin Wang; Zhiyou Wen; Shouwen Chen
      Pages: 7155 - 7164
      Abstract: Abstract Bacillus licheniformis WX-02 is a well-studied strain to produce poly-γ-glutamic acid (γ-PGA) with numerous applications. This study is to improve WX-02 strain’s capability of assimilating glycerol, a major byproduct of biofuels industries, through metabolic manipulation. Through gene knockout, the GlpK pathway was identified as the sole functional glycerol catabolism pathway, while the DhaK pathway was inactive for this strain under either aerobic or anaerobic conditions. The enhancement of glycerol utilization was attempted by substituting the native glpFK promoter with the constitutive promoter (P43), ytzE promoter (PytzE), and bacABC operon promoter (PbacA), respectively. The glycerol consumptions of the corresponding mutant strains WX02-P43glpFK, WX02-PytzEglpFK, and WX02-PbacAglpFK were 30.9, 26.42, and 18.8% higher than that of the WX-02 strain, respectively. The γ-PGA concentrations produced by the three mutant strains were 33.71, 23.39, and 30.05% higher than that of WX-02 strain, respectively. When biodiesel-derived crude glycerol was used as the carbon source, the mutant WX02-P43glpFK produced 16.63 g L−1 of γ-PGA, with a productivity of 0.35 g L−1 h−1. Collectively, this study demonstrated that glycerol can be used as an effective substrate for producing γ-PGA by metabolic engineering B. licheniformis strains.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8459-2
      Issue No: Vol. 101, No. 19 (2017)
       
  • Recombinant Lactococcus lactis expressing bioactive exendin-4 to promote
           insulin secretion and beta-cell proliferation in vitro
    • Authors: Zhu Zeng; Rui Yu; Fanglei Zuo; Bo Zhang; Huiqin Ma; Shangwu Chen
      Pages: 7177 - 7186
      Abstract: Abstract In recent years, therapeutic peptides have garnered great interest in the pharmaceutical industry for the treatment of diabetes. Lactic acid bacteria (LAB) are an appealing vehicle for safe and convenient oral delivery of bioactive peptide and protein drugs. Exendin-4 (Exd4) is a glucagon-like protein-1 (GLP-1) receptor agonist that is considered an excellent therapeutic peptide drug for type 2 diabetes due to its longer-lasting bioactivity, resulting from resistance to dipeptidyl peptidase 4. We explored Lactococcus lactis with the nisin-controlled gene expression (NICE) system as an oral delivery system for recombinant (r) Exd4 peptide in situ. Heterologous expression and secretion of rExd4 by L. lactis NZ9000/pNZ8048-rExd4 were successful and efficient under the NICE system. In vitro treatment with rExd4 significantly enhanced insulin secretion of INS-1 cells and activated the PI3-K/AKT signal pathway with protein levels of AKT and p-AKT increasing 1.6- to 1.8-fold compared to negative controls, similar to the positive GLP-1 controls. INS-1 cells treated with rExd4 also showed enhanced proliferation and inhibited apoptosis, corresponding with the effects of the standard Exd4 and GLP-1 treatments. Our data suggest that the rExd4 secreted by L. lactis is a bioactive insulinotropic peptide and functional GLP-1 receptor agonist that enhances glucose-dependent insulin secretion and activates the PI3-K/AKT signal pathway; furthermore, it may be involved in improving proliferation and inhibiting apoptosis of INS-1 cells in in vitro treatments. Therefore, L. lactis producing rExd4 may potentially serve as a novel strategy for oral treatment of diabetes.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8410-6
      Issue No: Vol. 101, No. 19 (2017)
       
  • 2′-Deoxyribosyltransferase from Leishmania mexicana , an efficient
           biocatalyst for one-pot, one-step synthesis of nucleosides from poorly
           soluble purine bases
    • Authors: N. Crespo; P. A. Sánchez-Murcia; F. Gago; J. Cejudo-Sanches; M. A. Galmes; Jesús Fernández-Lucas; José Miguel Mancheño
      Pages: 7187 - 7200
      Abstract: Abstract Processes catalyzed by enzymes offer numerous advantages over chemical methods although in many occasions the stability of the biocatalysts becomes a serious concern. Traditionally, synthesis of nucleosides using poorly water-soluble purine bases, such as guanine, xanthine, or hypoxanthine, requires alkaline pH and/or high temperatures in order to solubilize the substrate. In this work, we demonstrate that the 2′-deoxyribosyltransferase from Leishmania mexicana (LmPDT) exhibits an unusually high activity and stability under alkaline conditions (pH 8–10) across a broad range of temperatures (30–70 °C) and ionic strengths (0–500 mM NaCl). Conversely, analysis of the crystal structure of LmPDT together with comparisons with hexameric, bacterial homologues revealed the importance of the relationships between the oligomeric state and the active site architecture within this family of enzymes. Moreover, molecular dynamics and docking approaches provided structural insights into the substrate-binding mode. Biochemical characterization of LmPDT identifies the enzyme as a type I NDT (PDT), exhibiting excellent activity, with specific activity values 100- and 4000-fold higher than the ones reported for other PDTs. Interestingly, LmPDT remained stable during 36 h at different pH values at 40 °C. In order to explore the potential of LmPDT as an industrial biocatalyst, enzymatic production of several natural and non-natural therapeutic nucleosides, such as vidarabine (ara A), didanosine (ddI), ddG, or 2′-fluoro-2′-deoxyguanosine, was carried out using poorly water-soluble purines. Noteworthy, this is the first time that the enzymatic synthesis of 2′-fluoro-2′-deoxyguanosine, ara G, and ara H by a 2′-deoxyribosyltransferase is reported.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8450-y
      Issue No: Vol. 101, No. 19 (2017)
       
  • Recombinant expression and biochemical characterization of Mycobacterium
           tuberculosis 3Fe-4S ferredoxin Rv1786
    • Authors: Yun Lu; Feng Qiao; Yue Li; Xiao-Hong Sang; Cong-Ran Li; Jian-Dong Jiang; Xin-Yi Yang; Xue-Fu You
      Pages: 7201 - 7212
      Abstract: Abstract Ferredoxins are iron-sulfur protein that mediate electron transfer in cytochrome P450 mono-oxygenase (CYP)-related catalytic reactions in a wide variety of organisms. Rv1786 is a putative ferredoxin, encoded by a gene located downstream of the gene encoding CYP143A1 in the Mycobacterium tuberculosis genome. However, the structure and function of Rv1786 have remained unclear. Here, the recombinant Mtb Rv1786 was expressed, purified as a His-tagged form and characterized with [3Fe-4S] clusters as its cofactors using a series of measurements including SDS-PAGE, western blot, UV/Visible, MALDI-TOF/TOF-MS, and electron paramagnetic resonance spectroscopic analysis. Based on the assessments of surface plasmon resonance (SPR) and steady state kinetic assays, Rv1786 was found to be able to couple with both ferredoxin reductase A (FdrA) and flavoprotein reductase A (FprA) as redox partner, but with a stronger binding to FprA and a better coupling activity to FdrA. Preliminary structural and biochemical characterization of Mtb Rv1786 as a redox partner is presented here.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8454-7
      Issue No: Vol. 101, No. 19 (2017)
       
  • Storage lipid and polysaccharide metabolism in Yarrowia lipolytica and
           Umbelopsis isabellina
    • Authors: Marianna Dourou; Panagiotis Mizerakis; Seraphim Papanikolaou; George Aggelis
      Pages: 7213 - 7226
      Abstract: Abstract Complex biochemical mechanisms are being involved in oleaginous microorganisms during storage lipid and polysaccharide metabolism. Detailed biochemical analyses and monitoring of key enzymes involved in carbon metabolism were performed in Yarrowia lipolytica and Umbelopsis isabellina, which are often used as model oleaginous microorganisms. It was found that during the early oleaginous phase, the carbon source (glucose) was channeled to lipid accumulation, but also to polysaccharide biosynthesis. However, during transition from the early to the late oleaginous phase, glucose was exclusively converted to lipids, while in U. isabellina, but not in Y. lipolytica, an additional conversion of cellular polysaccharides into lipids was observed. After glucose depletion in the growth medium, cellular storage material was degraded either for generating maintenance energy or for supporting further microbial growth, depending on the availability of essential nutrients in the growth medium. We demonstrated that in both microorganisms, reserve lipids were exclusively used as an intra-cellular carbon source in order to generate energy for maintenance purpose. When cellular storage material degradation was related to new cell mass production, a bioconversion of lipids into new lipid-free material, consisting of polysaccharides and proteins, was observed in Y. lipolytica, while new lipid-free material in U. isabellina was richer in proteins. Lipid and polysaccharide remodeling may occur in some cases in both microorganisms. This study revealed some new biochemical features of oleaginous microorganisms that may be crucial for the design of new biotechnological processes, such as the production of bio-molecules of industrial, technological, and medical interest.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8455-6
      Issue No: Vol. 101, No. 19 (2017)
       
  • Cloning and characterization of Halomonas elongata L-asparaginase, a
           promising chemotherapeutic agent
    • Authors: Ali Ghasemi; Sedigheh Asad; Mahboubeh Kabiri; Bahareh Dabirmanesh
      Pages: 7227 - 7238
      Abstract: Abstract L-asparaginase has been used in the treatment of patients with acute lymphoblastic leukemia (ALL) for more than 30 years. Rapid clearance of the enzyme from blood stream and its L-glutaminase-dependent neurotoxicity has led to searching for new L-asparaginases with more desirable properties. In the present study, L-asparaginase coding gene of Halomonas elongata was isolated, expressed in Escherichia coli, purified, and characterized. The purified protein was found to have a molecular mass of 39.5 kDa and 1000-folds more activity towards L-asparagine than L-glutamine. Enzyme-specific activity towards L-asparagine was determined to be 1510 U/mg, which is among the highest reported values for microbial L-asparaginases. K m , Vmax, and k cat values were 5.6 mM, 2.2 μmol/min, and 1.96 × 103 1/S, respectively. Optimum temperature was found to be 37 °C while the enzyme showed maximum activity at a wide pH range (from 6 to 9). Enzyme half-life in the presence of human serum at 37 °C was 90 min which is three times higher when compared with reported values for E. coli L-asparaginase. Enzyme showed cytotoxic effects against Jurkat and U937 cell lines with an IC50 of 2 and 1 U/ml, respectively. Also, no toxic effects on human erythrocytes and Chinese hamster ovary cell lines were detected, and just minor inhibitory effects on human umbilical vein endothelial cells were observed. This is the first report describing the therapeutic potentials of a recombinant L-asparaginase isolated from a halophilic bacterium as an anticancer agent.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8456-5
      Issue No: Vol. 101, No. 19 (2017)
       
  • Activity of human beta defensin-1 and its motif against active and dormant
           Mycobacterium tuberculosis
    • Authors: Richa Sharma; Uma Nahar Saikia; Sadhna Sharma; Indu Verma
      Pages: 7239 - 7248
      Abstract: Abstract The ineffectiveness of anti-tuberculous therapy against dormant and drug-resistant mycobacteria demands scrutiny of alternative candidates like antimicrobial peptides having different mechanisms of action. The present study was designed to explore the activity of human beta defensin-1 (HBD-1) and its in silico identified short motif Pep-B against active and dormant Mycobacterium tuberculosis (M. tb) H37Rv. Activity of HBD-1 and Pep-B was determined against actively growing M. tb in vitro, inside monocyte-derived macrophages (MDMs) and dormant bacilli in in vitro potassium deficiency and human peripheral blood mononuclear cell (PBMC) granuloma models using colony-forming unit enumeration. The minimum inhibitory concentrations (MIC) of HBD-1 and Pep-B were found to be 2 and 20 μg/ml, respectively. These peptides also inhibited intracellular mycobacterial growth at concentrations lower than in vitro MICs along with increased IFN-γ levels. Although at higher concentration, HBD-1 (× 2 MIC) and Pep-B (× 2 MIC) led to decrease in in vitro dormant mycobacterial load as compared to rifampicin (× 25 MIC) and isoniazid (× 16 MIC). Similarly, both peptides showed higher killing efficacy against dormant mycobacteria inside granuloma as compared to rifampicin. Thus, the present study indicates that HBD-1 and its motif are effective antimicrobial players against both actively growing and dormant mycobacteria.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8466-3
      Issue No: Vol. 101, No. 19 (2017)
       
  • Development of the first gene expression system for Salinicoccus strains
           with potential application in bioremediation of hypersaline wastewaters
    • Authors: Dahe Zhao; Haibo Yang; Junyu Chen; Feiyue Cheng; Sumit Kumar; Jing Han; Ming Li; Jian Zhou; Hua Xiang
      Pages: 7249 - 7258
      Abstract: Abstract Salinicoccus salsiraiae IM408 (=CGMCC13032) is a novel halophilic bacterium that we isolated from the saline soil of Da Gang Oilfield. It tolerates 60 g/l sodium chloride and up to 123 g/l (1.5 M) sodium acetate and has shown a potential application in bioremediation of wastewater with high salt and high chemical oxygen demand (COD). Two plasmids, pS408-1 and pS408-2, were identified in S. salsiraiae IM408, and the sequences and copy numbers of the plasmids were determined. Based on these plasmids, two shuttle vectors containing a replicon for Escherichia coli, ampicillin, and chloramphenicol resistance genes, as well as the replicon from pS408-1 or pS408-2, were constructed and named as pTCS101 and pTCS201, respectively. A suitable host strain, named S. salsiraiae PE01, was also developed from the wild-type by plasmid elimination. Using the plasmid pTCS101 as an expression vector, l-lactate dehydrogenase from Staphylococcus aureus was expressed successfully in S. salsiraiae PE01. This is the first gene expression system for the Salinicoccus genus. It has provided the potential for expression of desired proteins or for establishment of desired pathways in Salinicoccus strains, which would make these halophiles more advantageous in future biotechnological applications.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8428-9
      Issue No: Vol. 101, No. 19 (2017)
       
  • Armored DNA in recombinant Baculoviruses as controls in molecular genetic
           assays
    • Authors: Andrea Freystetter; Christian Paar; Herbert Stekel; Jörg Berg
      Pages: 7259 - 7269
      Abstract: Abstract The widespread use of molecular PCR-based assays in analytical and clinical laboratories brings about the need for test-specific, stable, and reliable external controls (EC) as well as standards and internal amplification controls (IC), in order to arrive at consistent test results. In addition, there is also a growing need to produce and provide stable, well-characterized molecular controls for quality assurance programs. In this study, we describe a novel approach to generate armored double-stranded DNA controls, which are encapsulated in baculovirus (BV) particles of the species Autographa californica multiple nucleopolyhedrovirus. We used the well-known BacPAK™ Baculovirus Expression System (Takara-Clontech), removed the polyhedrin promoter used for protein expression, and generated recombinant BV-armored DNAs. The obtained BV-armored DNAs were readily extracted by standard clinical DNA extraction methods, showed favorable linearity and performance in our clinical PCR assays, were resistant to DNase I digestion, and exhibited marked stability in human plasma and serum. BV-armored DNA ought to be used as ECs, quantification standards, and ICs in molecular assays, with the latter application allowing for the entire monitoring of clinical molecular assays for sample adequacy. BV-armored DNA may also be used to produce double-stranded DNA reference materials for, e.g., quality assurance programs. The ease to produce BV-armored DNA should make this approach feasible for a broad spectrum of molecular applications. Finally, as BV-armored DNAs are non-infectious to mammals, they may be even more conveniently shipped than clinical specimen.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8436-9
      Issue No: Vol. 101, No. 19 (2017)
       
  • Orf6 gene encoded glyoxalase involved in mycotoxin citrinin biosynthesis
           in Monascus purpureus YY-1
    • Authors: Bin Liang; Xinjun Du; Ping Li; Hui Guo; Chanchan Sun; Jianxin Gao; Shuo Wang
      Pages: 7281 - 7292
      Abstract: Abstract As traditional edible fungi, Monascus spp. have been widely used as folk medicine, food colorants, and fermentation starters in East Asian countries for more than a thousand years. However, the presence of citrinin, which has nephrotoxic, hepatotoxic, and carcinogenic activities, raises suspicions about the safety of Monascus products. Citrinin biosynthesis in Monascus is known to occur via a polyketide pathway and a citrinin biosynthesis gene cluster, which include the characterized polyketide synthetase pksCT. A gene, orf6, encodes a protein that shows significant similarity to glyoxalase and is located between ctnE and orf1. This study analyzed orf6 function, and successfully obtained an orf6 disruption strain (Δorf6). Citrinin production was significantly greater (3.6-fold) in the Δorf6 strain than in the wild-type Monascus purpureus YY-1, and RT-PCR analysis further revealed increased expression of numerous genes of the citrinin biosynthesis gene cluster in Δorf6. Therefore, orf6 proved to be a major inhibitor, directly involved in citrinin biosynthesis. Moreover, pigment production in Δorf6 was reduced by approximately 30%, while the transcription levels of many genes involved in Monascus pigments (MPs) biosynthesis had increased. This dichotomy indicated that MPs and citrinin yields may be improved simultaneously; however, a portion of the pigments was consumed to protect the cells from oxidative damage in the Δorf6 strain. An Δorf6 revertant restored the citrinin and pigment yields to normal levels. This study makes a contribution to explore the citrinin biosynthesis pathway and provides some theoretical guidance to improving the safety of Monascus-related products.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8462-7
      Issue No: Vol. 101, No. 19 (2017)
       
  • Design and development of a workflow for microbial spray formulations
           including decision criteria
    • Authors: Ana Bejarano; Ursula Sauer; Claudia Preininger
      Pages: 7335 - 7346
      Abstract: Abstract Herein, we present a workflow for the development of talc-based microbial inoculants for foliar spray consisting of four steps. These include together with decision-making criteria (1) the selection of additives based on their capability to wet juvenile maize leaves, (2) their adhesion on the plant, (3) their interaction with the biological systems, and (4) the choice of thickener for good dispersion stability. In total, 29 additives including polysaccharides and proteins, polyols, glycosides, oils, waxes, and surfactants (e.g., chitosan, gelatin, glycerol, saponin, castor oil, polyethylene, rhamnolipid) were evaluated. Contact angle and spreading index measurements revealed that the use of 5% Geloil, 1% rhamnolipid, or suitable combinations of Geloil + rhamnolipid and Nurture Yield S 2002 + rhamnolipid enhanced wetting of hydrophobic maize leaves and adherence, similarly to the commercial wetting agents recommended for plant protection 1% Prev B2 and 1% Trifolio S Forte. Interaction of additives with biological systems was based on biocompatibility and phytotoxicity assays, and cell viability monitoring using the endophytic Gram-negative bacterium Paraburkholderia phytofirmans PsJN. Results from biocompatibility assays indicated that in contrast to rhamnolipid and Prev B2 Geloil, Nurture Yield S 2002 and Trifolio S Forte fully supported bacterial growth within a concentration range of 1 to 5%. Dose-dependent phytotoxicity was observed in plants treated with rhamnolipid. Most efficient formulation was composed of PsJN, talc, xanthan, and Geloil. Beyond that, the proposed workflow is expected to generally provide guidance for the development of spray formulations and help other researchers to optimize their choices in this area.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8447-6
      Issue No: Vol. 101, No. 19 (2017)
       
  • TCDD administered on activated carbon eliminates bioavailability and
           subsequent shifts to a key murine gut commensal
    • Authors: Robert D. Stedtfeld; J. Brett Sallach; Robert B. Crawford; Tiffany M. Stedtfeld; Maggie R. Williams; Hassan Waseem; Cliff T. Johnston; Hui Li; Brian J. Teppen; Norbert E. Kaminski; Stephen A. Boyd; James M. Tiedje; Syed A. Hashsham
      Pages: 7409 - 7415
      Abstract: Abstract Activated carbon (AC) is an increasingly attractive remediation alternative for the sequestration of dioxins at contaminated sites globally. However, the potential for AC to reduce the bioavailability of dioxins in mammals and the residing gut microbiota has received less attention. This question was partially answered in a recent study examining 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced hallmark toxic responses in mice administered with TCDD sequestered by AC or freely available in corn oil by oral gavage. Results from that study support the use of AC to significantly reduce the bioavailability of TCDD to the host. Herein, we examined the bioavailability of TCDD sequestered to AC on a key murine gut commensal and the influence of AC on the community structure of the gut microbiota. The analysis included qPCR to quantify the expression of segmented filamentous bacteria (SFB) in the mouse ileum, which has responded to TCDD-induced host toxicity in previous studies and community structure via sequencing the 16S ribosomal RNA (rRNA) gene. The expression of SFB 16S rRNA gene and functional genes significantly increased with TCDD administered with corn oil vehicle. Such a response was absent when TCDD was sequestered by AC. In addition, AC appeared to have a minimal influence on murine gut community structure and diversity, affecting only the relative abundance of Lactobacillaceae and two other groups. Results of this study further support the remedial use of AC for eliminating bioavailability of TCDD to host and subsequent influence on the gut microbiome.
      PubDate: 2017-10-01
      DOI: 10.1007/s00253-017-8460-9
      Issue No: Vol. 101, No. 19 (2017)
       
  • Influence of oxygen availability on the metabolism and morphology of
           Yarrowia lipolytica : insights into the impact of glucose levels on
           dimorphism
    • Authors: Asma Timoumi; Carine Bideaux; Stéphane E. Guillouet; Yohan Allouche; Carole Molina-Jouve; Luc Fillaudeau; Nathalie Gorret
      Abstract: Abstract Dynamic behavior of Yarrowia lipolytica W29 strain under conditions of fluctuating, low, and limited oxygen supply was characterized in batch and glucose-limited chemostat cultures. In batch cultures, transient oscillations between oxygen-rich and -deprived environments induced a slight citric acid accumulation (lower than 29 mg L−1). By contrast, no citric acid was detected in continuous fermentations for all stress conditions: full anoxia (zero pO2 value, 100% N2), limited (zero pO2 value, 75% of cell needs), and low (pO2 close to 2%) dissolved oxygen (DO) levels. The macroscopic behavior (kinetic parameters, yields, viability) of Y. lipolytica was not significantly affected by the exposure to DO fluctuations under both modes of culture. Nevertheless, conditions of oxygen limitation resulted in the destabilization of the glucose-limited growth during the continuous cultivations. Morphological responses of Y. lipolytica to DO oscillations were different between batch and chemostat runs. Indeed, a yeast-to-mycelium transition was induced and progressively intensified during the batch fermentations (filamentous subpopulation reaching 74% (v/v)). While, in chemostat bioreactors, the culture consisted mainly of yeast-like cells (mean diameter not exceeding 5.7 μm) with a normal size distribution. During the continuous cultures, growth at low DO concentration did not induce any changes in Y. lipolytica morphology. Dimorphism (up to 80.5% (v/v) of filaments) was only detected under conditions of oxygen limitation in the presence of a residual glucose excess (more than 0.75 g L−1). These data suggest an impact of glucose levels on the signaling pathways regulating dimorphic responses in Y. lipolytica.
      PubDate: 2017-09-06
      DOI: 10.1007/s00253-017-8446-7
       
  • Comparison of EMA-, PMA- and DNase qPCR for the determination of microbial
           cell viability
    • Authors: B. Reyneke; T. Ndlovu; S. Khan; W. Khan
      Abstract: Abstract Ethidium monoazide (EMA) quantitative polymerase chain reaction (qPCR), propidium monoazide (PMA)-qPCR and DNase treatment in combination with qPCR were compared for the determination of microbial cell viability. Additionally, varying EMA and PMA concentrations were analysed to determine which dye and concentration allowed for the optimal identification of viable cells. Viable, heat treated (70 °C for 15 min) and autoclaved cultures of Legionella pneumophila, Pseudomonas aeruginosa, Salmonella typhimurium, Staphylococcus aureus and Enterococcus faecalis were utilised in the respective viability assays. Analysis of the viable and heat-treated samples indicated that variable log reductions were recorded for both EMA [log reductions ranging from 0.01 to 2.71 (viable) and 0.27 to 2.85 (heat treated)], PMA [log reductions ranging from 0.06 to 1.02 (viable) and 0.62 to 2.46 (heat treated)] and DNase treatment [log reductions ranging from 0.06 to 0.82 (viable) and 0.70 to 2.91 (heat treated)], in comparison to the no viability treatment controls. Based on the results obtained, 6 μM EMA and 50 μM PMA were identified as the optimal dye concentrations as low log reductions were recorded (viable and heat-treated samples) in comparison to the no viability treatment control. In addition, the results recorded for the 6 μM EMA concentration were comparable to the results obtained for both the 50 μM PMA and the DNase treatment. The use of EMA-qPCR (6 μM) may therefore allow for the rapid identification and quantification of multiple intact opportunistic pathogens in water sources, which would benefit routine water quality monitoring following disinfection treatment.
      PubDate: 2017-09-05
      DOI: 10.1007/s00253-017-8471-6
       
  • PhzA , the shunt switch of phenazine-1,6-dicarboxylic acid biosynthesis in
           Pseudomonas chlororaphis HT66
    • Authors: Shuqi Guo; Yining Wang; Bona Dai; Wei Wang; Hongbo Hu; Xianqing Huang; Xuehong Zhang
      Abstract: Abstract Natural phenazines are versatile secondary metabolites that are mainly produced by Pseudomonas and Streptomyces. All phenazine-type metabolites originate from two precursors: phenazine-1-carboxylic acid (PCA) in Pseudomonas or phenazine-1,6-dicarboxylic acid (PDC) in Streptomyces and other bacteria. Although the biosynthesis of PCA in Pseudomonas has been extensively studied, the origin of PDC still remains unclear. Comparing the phenazine biosynthesis operons of different species, we found that the phzA gene was restricted to Pseudomonas in which PCA is produced. By generating phzA-inactivated mutant, we found a new compound obviously accumulated; it was then isolated and identified as PDC. Protein sequence alignment showed that PhzA proteins from Pseudomonas form a separate group that is recognized by H73L and S77L mutations. Generating mutations of L73 into H73 and L77 into S77 resulted in a significant increase in PDC production. These findings suggest that phzA may act as a shunt switch of PDC biosynthesis in Pseudomonas and distinguish the pathway producing only PCA from the pathway forming PCA plus PDC. Using real-time PCR analysis, we suggested that the phzA, phzB, and phzG genes either directly or indirectly regulate the production of PDC, and phzA plays the most significant regulatory role. This is the first description of phzA in the biosynthesis of PDC, and the first-time substantial PDC was obtained in Pseudomonas. Therefore, this study not only provides valuable clues to better understand the biosynthesis of PCA and PDC in Pseudomonas but also introduces a method to produce PDC derivatives by genetically engineered strains.
      PubDate: 2017-09-05
      DOI: 10.1007/s00253-017-8474-3
       
  • Preparation, characterization and toxicity evaluation of amphotericin B
           loaded MPEG-PCL micelles and its application for buccal tablets
    • Authors: Peipei Zhang; Xiaofeng Yang; Yanhao He; Zhuo Chen; Bing Liu; Cota Segura Emesto; Guangde Yang; Weirong Wang; Jiye Zhang; Rong Lin
      Abstract: Abstract Oral candidiasis or thrush is a fungal infection due to Candida albicans, causing discomfort in areas inside mouth or tongue. The clinical application of antifungal reagent amphotericin B (AMB), which is believed to offer a better treatment for oral candidiasis, is greatly compromised by its toxicities (mainly nephrotoxicity) and poor solubility. In order to overcome these issues, we characterized AMB-loaded MPEG-PCL micelles in vitro and in vivo. In addition, the antifungal activities of AMB/MPEG-PCL micelles-loaded buccal tablet were also evaluated in vitro. We found that micelles system could significantly improve the solubility of AMB yet reduce the overall toxicity, while the buccal tablet system is capable to suppress C. albicans biofilm formation. Furthermore, the toxicity of the buccal tablet system is also reduced compared with other standard preparations. Therefore, the prepared tablet with AMB-loaded MPEG-PCL micelles as oral topical preparations has the potential to improve current treatment of superficial oral C. albicans infections.
      PubDate: 2017-09-03
      DOI: 10.1007/s00253-017-8463-6
       
 
 
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