Xianghui Qi

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The main purpose of this study was to develop a pure culture starter for producing kefir. In order to accomplish starter recycling, yeasts (Kluyveromyces marxianus strain, Pichia kudriavzevii clone), lactic acid bacteria (Lactobacillus kefiri strain F4Aa, Lactobacillus kefiri strain NM131-7, Lactobacillus kefiri strain NM132-3, Lactobacillus kefiri strain(More)
Glycerol dehydratase (GDHt) is a key and rate-limiting enzyme in the pathway of 1,3-propanediol (1,3-PD) synthesis. The improvement of GDHt’s stability and enzymatic activity is desirable for the biosynthesis of 1,3-PD. The gldABC gene encoding GDHt of Klebsiella pneumoniae was cloned and expressed in Escherichia coli XL10-Gold, and the mutation sites of(More)
Understanding of the molecular mechanism and biological implication underlying the difference in binding of substrate peptides and small-molecule inhibitors to multidrug-resistant mutants of HIV-1 protease would help to develop new anti-HIV agents combating drug resistance. Here, an integration of rigorous quantum mechanics/molecular mechanics (QM/MM)(More)
We present a novel method to phase lock two lasers with a controllable frequency difference. A microwave frequency-modulated vertical-cavity surface-emitting laser is used to phase connect two diode lasers by a two-step injection locking. The phase fluctuations of the two lasers are measured to be 6.4 x 10(-4) rad2, corresponding to 99.94% phase coherence.(More)
Synthesis of 1,3-propanediol (1,3-PD) from glycerol through the biotransformation process requires two steps, catalyzed by glycerol dehydratase (GDHt) and 1,3-PD oxidoreductase. GDHt is the rate-limiting enzyme in this process. All recombinant microorganisms for production of 1,3-PD so far utilized the natural genes that may not have been optimized. Two(More)
1,3-Propanediol (1,3-PD), an important material for chemical industry, is biologically synthesized by glycerol dehydratase (GDHt) and 1,3-propanediol dehydrogenase (PDOR). In present study, the dhaBCE and dhaT genes encoding glycerol dehydratase and 1,3-propanediol dehydrogenase respectively were cloned from Citrobacter freundii and co-expressed in E. coli.(More)
Multidrug resistance (MDR) occurs when a tumor develops resistance to multiple chemotherapeutic drugs, which may include antitumor drugs with different chemical structures and mechanisms. MDR limits the treatment effects of antitumor drugs, and is the main cause of chemotherapy failure. MDR is caused by numerous factors including changes in ABC(More)
We present an unconventional experimental approach for detecting saturated absorption spectroscopy. Using this approach, crossover peaks are displaced, leaving out peaks corresponding to an atom's natural resonant frequencies. Sensitivity of detection can also be enhanced. Consequently, the spectrum could reflect the energy structure of atoms more(More)
The Clostridium acetobutylicum gene Ca-SacB encoding levansucrase was cloned and expressed in Escherichia coli. Ca-SacB is composed of 1287 bp and encodes 428 amino acid residues, which could convert 150 mmol/L sucrose to levan with the liberation of glucose. The optimum pH and temperature of this enzyme for levan formation were pH 6 and 60 °C,(More)
Aerobic granules for sulphide and ammonium removal were cultivated in a sequencing batch reactor, and the microbial community of the aerobic granules was investigated by denaturing gradient gel electrophoresis. The loading rate increased from 0.15 to 0.9 kg S2− m−3 d−1, and the removal efficiencies of sulphide, chemical oxygen demand, and NH4 +-N were(More)