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Liu G.-L.,Ocean University of China | Wang K.,Marine Chemical Research Institute | Hua M.-X.,Ocean University of China | Buzdar M.A.,Ocean University of China | Chi Z.-M.,Ocean University of China
Process Biochemistry | Year: 2012

The psychrotolerant yeast Mrakia frigida 2E00797 isolated from sea sediments in Antarctica was found to be able to produce killer toxin against Metschnikowia bicuspidata, Candida tropicalis and Candida albicans. In the present study, the killer toxin was purified and characterized. The molecular weight of the purified killer toxin was estimated to be 55.6 kDa and the purified killer toxin shared 35.1% sequence homology with a protein kinase. The purified killer toxin's optimal temperature and pH for killing activity were 16 °C and 4.5, respectively, and it was stable in the temperature range from 10 to 25 °C at pH 4.5. The toxin's highest killing activity was observed in the presence of 3.0 g/100 ml NaCl. The purified killer toxin was able to actively kill whole cells of M. bicuspidata but could not kill the protoplast of the sensitive yeast. Of the eight yeast species tested in this study, the killer toxin was able to kill C. tropicalis and C. albicans in addition to M. bicuspidata. © 2012 Elsevier Ltd. All rights reserved. Source


Sun H.-Y.,Ocean University of China | Wang K.,Marine Chemical Research Institute | Chi Z.,Ocean University of China | Xu H.-M.,Ocean University of China | Chi Z.-M.,Ocean University of China
Process Biochemistry | Year: 2012

The yeast Wickerhamomyces anomalus (the previous name was Pichia anomala) HN1-2 isolated from the mangrove ecosystem was found to be able to produce high level of both killer toxin and single cell protein. When the killer yeast cells were grown by batch cultivation in 5-l fermentor, crude protein in the cells, cell mass, reducing sugar, and diameter of the inhibition zone reached 56.0 g per 100 g of cell dry weight, 7.3 g per liter, 9.5 g per liter, and 19.0 mm, respectively within 12 h and this yeast synthesized a large amount of the essential amino acids, such as lysine (7.8%), methionine (1.8%), and leucine (9.0%). The crude killer toxin produced by the killer yeast isolate HN1-2 could kill the cells of Lodderomyces elongisporus, Candida albicans, Metschnikowia bicuspidata, Pichia guilliermondii, Saccharomyces cerevisiae, Yarrowia lipolytica, and Kluyveromyces aestuarii, which were widely distributed in natural marine environments. The results also showed that the undesirable yeast could be avoided during cell growth of the killer yeast. © 2011 Elsevier Ltd. All rights reserved. Source


Jiao C.,Qingdao University of Science and Technology | Zhuo J.,Qingdao University of Science and Technology | Chen X.,Qingdao University of Science and Technology | Li S.,Qingdao University of Science and Technology | Wang H.,Marine Chemical Research Institute
Journal of Thermal Analysis and Calorimetry | Year: 2013

Flame retardant epoxy resin (FREP) were synthesized from phosphoric acid and bisphenol A epoxy resin (BAEP). The structure of the FREP was characterized using FTIR and 31P NMR. Then, several FREP/BAEP mass ratios were used to obtain materials with different phosphorus contents. The properties of the thermosetting materials were evaluated by limiting oxygen index, UL 94, cone calorimeter test, and thermogravimetric analysis. The results showed that the heat release rates and smoke production rates decreased greatly, and char residue increased with the increasing of FREP. It indicates that good flame retardant properties are related to the formation of a protective phosphorus-rich char layer. © 2012 Akadémiai Kiadó, Budapest, Hungary. Source


Wang Z.,Hubei University | Wang Z.,Marine Chemical Research Institute | Qi Y.,Hubei University | Qi H.,Qingdao University | And 2 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2010

Hollow and hierarchical Bi 3.15Nd 0.85Ti 3O 12 (BNdT) microspheres of 0.5-1.2 lm in diameter were synthesized through a hydrothermal process. Each hollow microsphere is constructed across by many single-crystalline BNdT nanoplates with in-plane dimension of ∼400 nm. The BNdT nanoplates are of layered perovskites. The UV-visible absorption characteristics demonstrated that the band gap of the BNdT microspheres is 3.33 eV. The hierarchical microspheres exhibit significant photocatalytic activity. Up to 75% methyl orange was decolorized after UV irradiation for 210 min, whereas lower than 10% methyl orange decolorized using BNdT powders prepared from single crystals as catalyst. The photocatalytic decolorization of methyl orange solution is a pseudo-first-order reaction and its kinetics can be expressed as ln(C/C 0) = kt. © Springer Science+Business Media, LLC 2010. Source


Li Y.,Ocean University of China | Liu G.-L.,Ocean University of China | Wang K.,Marine Chemical Research Institute | Chi Z.-M.,Ocean University of China | Madzak C.,Ocean University of China
Journal of Molecular Catalysis B: Enzymatic | Year: 2012

The endo-inulinase gene (EnIA) from Arthrobacter sp. S37 was ligated into the expression vector pINA1317 and over-expressed in Yarrowia lipolytica Po1h. It was found that the endo-inulinase activity and specific endo-inulinase activity produced by the transformant 1317-EnIA were 16.7 U/mL and 93.4 U/mg, respectively. The recombinant EnIA was purified and characterized. The molecular weight of the purified rEnIA was 78.9 kDa. The optimal pH and temperature of the purified rEnIA were 4 and 50 °C, respectively. The purified rEnIA was stable in the temperature range of 4-40 °C and in the pH range of 2-8. The activity of rEnIA was greatly stimulated in the presence of Li+. The purified rEnIA could actively convert inulin into disaccharides. .© 2011 Elsevier B.V. All rights reserved. Source

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