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1
Enzymatic Production of High Molecular Weight Chitooligosaccharides Using Recombinant Chitosanase from Bacillus thuringiensis BMB171

( Lixin Kang ),( Sijing Jiang ),( Lixin Ma ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 한국미생물·생명공학회지 Vol.46 No.1
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The chitosanase gene (btbchito) of Bacillus thuringiensis BMB171 was cloned and heterologously expressed in the yeast Pichia pastoris. After purification, about 300 mg of recombinant chitosanase was obtained from the 1-1 culture medium with a specific activity of 240 units/mg. Results determined by the combined use of thin layer chromatography (TLC) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) showed that the chitooligosaccharides (COSs) obtained by chitosan (N-deacetylated by 70%, 80%, and 90%) hydrolysis by rBTBCHITO were comprised of oligomers, with degrees of polymerization (DP) mainly ranging from trimers to heptamers; high molecular weight chitopentaose, chitohexaose, and chitoheptaose were also produced. Hydrolysis products was also deduced using MS since the COSs (n) are complex oligosaccharides with various acetyl groups from one to two, so the non-acetyl COSs (GlcN)n and COSs with more acetyls (> 2) were not detected. The employment of this method in the production of high molecular weight COSs may be useful for various industrial and biological applications, and the activity of chitosanase has great significance in research and other applications.
2
Enzymatic Production of High Molecular Weight Chitooligosaccharides Using Recombinant Chitosanase from Bacillus thuringiensis BMB171

Kang, Lixin,Jiang, Sijing,Ma, Lixin The Korean Society for Microbiology and Biotechnol 2018 한국미생물·생명공학회지 Vol.46 No.1
- 원문보기
The chitosanase gene (btbchito) of Bacillus thuringiensis BMB171 was cloned and heterologously expressed in the yeast Pichia pastoris. After purification, about 300 mg of recombinant chitosanase was obtained from the 1-1 culture medium with a specific activity of 240 units/mg. Results determined by the combined use of thin layer chromatography (TLC) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) showed that the chitooligosaccharides (COSs) obtained by chitosan (N-deacetylated by 70%, 80%, and 90%) hydrolysis by rBTBCHITO were comprised of oligomers, with degrees of polymerization (DP) mainly ranging from trimers to heptamers; high molecular weight chitopentaose, chitohexaose, and chitoheptaose were also produced. Hydrolysis products was also deduced using MS since the COSs (n) are complex oligosaccharides with various acetyl groups from one to two, so the non-acetyl COSs (GlcN)n and COSs with more acetyls (> 2) were not detected. The employment of this method in the production of high molecular weight COSs may be useful for various industrial and biological applications, and the activity of chitosanase has great significance in research and other applications.
3
Pyramid-like CdS nanoparticles grown on porous TiO2 monolith: An advanced photocatalyst for H2 production

Du, Jimin,Wang, Huiming,Yang, Mengke,Li, Kaidi,Zhao, Lixin,Zhao, Guoyan,Li, Sujuan,Gu, Xiaolei,Zhou, Yalan,Wang, Le,Gao, Yating,Wang, Weimin,Kang, Dae Joon Pergamon Press 2017 Electrochimica Acta Vol. No.
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Abstract Efficient production of H2 via solar-light-driven water splitting by a semiconductor-based photocatalyst without noble metals is crucial owing to increasingly severe global energy and environmental issues. However, many challenges, including the low efficiency of H2 evolution, low solar light absorption, excited electron–hole pair recombination, and slow transport of photoexcited carriers, must be resolved to enhance the H2 photoproduction efficiency and photocatalyst stability. Here, a two-step method is used to synthesize advanced H2-generating photocatalysts consisting of pyramid-like CdS nanoparticles grown on a porous TiO2 monolith, which show promising photocatalytic activity for the hydrogen evolution reaction. Furthermore, the stability of the photocatalysts is examined through long-term tests to verify their good durability. Without noble metals as cocatalysts, the photocatalyst can reach a high H2 production rate of 1048.7μmolh−1 g−1 under UV–vis irradiation when the ratio of the CdS nanoparticles to TiO2 is 5mol%. This unusual photocatalytic activity arises from the wide-region light adsorption due to the narrow band gap of CdS, effective separation of electrons and holes due to conduction band alignment at the CdS–TiO2 interface, and favorable reaction sites resulting from the porous structure.