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Creation of High-Yield Polyhydroxyalkanoates Engineered Strains by Low Energy Ion Implantation
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作者 钱时权 程郢 +1 位作者 朱苏文 程备久 《Plasma Science and Technology》 SCIE EI CAS CSCD 2008年第6期769-774,共6页
Polyhydroxyalkanoates (PHAs), as a candidate for biodegradable plastic materials, can be synthesized by numerous microorganisms. However, as its production cost is high in comparison with those of chemically synthes... Polyhydroxyalkanoates (PHAs), as a candidate for biodegradable plastic materials, can be synthesized by numerous microorganisms. However, as its production cost is high in comparison with those of chemically synthesized plastics, a lot of research has been focused on the efficient production of PHAs using different methods. In the present study, the mutation effects of PHAs production in strain pCB4 were investigated with implantation of low energy ions. It was found that under the implantation conditions of 7.8×10^14 N^+/cm^2 at 10 keV, a high-yield PHAs strain with high genetic stability was generated from many mutants. After optimizing its fermentation conditions, the biomass, PHAs concentration and PHAs content of pCBH4 reached 2.26 g/L, 1.81 g/L, and 80.08% respectively, whereas its wild type controls were about 1.24 g/L, 0.61 g/L, and 49.20%. Moreover, the main constituent of PHAs was identified as poly-3-hydroxybutyrates (PHB) in the mutant stain and the yield of this compound was increased up to 41.33% in contrast to that of 27.78% in the wild type strain. 展开更多
关键词 polyhydroxyalkanoates(PHAs) pCBH4 low energy ion implantation MUTATion
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High-Temperature Annealing Induced He Bubble Evolution in Low Energy He Ion Implanted 6H-SiC 被引量:1
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作者 刘玉柱 李炳生 张莉 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第5期40-43,共4页
Bubble evolution in low energy and high dose He-implanted 6H-SiC upon thermal annealing is studied. The (0001)-oriented 6H-SiC wafers are implanted with 15keV helium ions at a dose of 1×10^17 cm^-2 at room temp... Bubble evolution in low energy and high dose He-implanted 6H-SiC upon thermal annealing is studied. The (0001)-oriented 6H-SiC wafers are implanted with 15keV helium ions at a dose of 1×10^17 cm^-2 at room temperature. The samples with post-implantation are annealed at temperatures of 1073, 1173, 1273, and 1473K for 30rain. He bubbles in the wafers are examined via cross-sectional transmission electron microscopy (XTEM) analysis. The results present that nanoscale bubbles are almost homogeneously distributed in the damaged layer of the as-implanted sample, and no significant change is observed in the He-implanted sample after 1073 K annealing. Upon 1193 K annealing, almost full recrystallization of He-implantation-induced amorphization in 6H-SiC is observed. In addition, the diameters of He bubbles increase obviously. With continually increasing temperatures to 1273K and 1473 K, the diameters of He bubbles increase and the number density of lattice defects decreases. The growth of He bubbles after high temperature annealingabides by the Ostwald ripening mechanism. The mean diameter of He bubbles located at depths of 120-135 nm as a function of annealing temperature is fitted in terms of a thermal activated process which yields an activation energy of 1.914+0.236eV. 展开更多
关键词 High-Temperature Annealing Induced He Bubble Evolution in low energy He ion Implanted 6H-SiC HRTEM
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A Mutant of Bacillus Subtilis with High-Producing Surfactin by Ion Beam Implantation 被引量:6
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作者 刘清梅 袁航 +6 位作者 王军 贡国鸿 周伟 樊永红 王丽 姚建铭 余增亮 《Plasma Science and Technology》 SCIE EI CAS CSCD 2006年第4期491-496,共6页
In order to generate a mutant of Bacillus subtilis with enhanced surface activity through low energy nitrogen ion beam implantation, the effects of energy and dose of ions implanted were studied. The morphological cha... In order to generate a mutant of Bacillus subtilis with enhanced surface activity through low energy nitrogen ion beam implantation, the effects of energy and dose of ions implanted were studied. The morphological changes in the bacteria were observed by scanning electron microscope (SEM). The optimum condition of ions implantation, 20 keV of energy and 2.6 × 10^15N^+/cm^2 in dose, was determined. A mutant, B.s-E-8 was obtained, whose surface activity of 50-fold and 100-fold diluted cell-free Landy medium was as 5.6-fold and 17.4-fold as the wild strain. The microbial growth and biosurfactant production of both the mutant and the wild strain were compared. After purified by ultrafiltration and SOURCE 15PHE, the biosurfactant was determined to be a complex of surfactin family through analysis of electrospray ionization mass spectrum (ESI/MS) and there was an interesting finding that after the ion beam implantation the intensities of the components were different from the wild type strain. 展开更多
关键词 bacillus subtilis SURFACTIN low energy ion beam implantation mutation breeding
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A Mutant Strain of a Surfactant-Producing Bacterium with Increased Emulsification Activity 被引量:4
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作者 刘清梅 姚建铭 +1 位作者 潘仁瑞 余增亮 《Plasma Science and Technology》 SCIE EI CAS CSCD 2005年第3期2889-2892,共4页
As reported in this paper, a strain of oil-degrading bacterium Sp - 5 - 3 was determined to belong to Enterobacteriaceae, which would be useful for microbial enhanced oil recovery (MEOR). The aim of our study was to g... As reported in this paper, a strain of oil-degrading bacterium Sp - 5 - 3 was determined to belong to Enterobacteriaceae, which would be useful for microbial enhanced oil recovery (MEOR). The aim of our study was to generate a mutant using low energy N+ beam implantation. With 10 keV of energy and 5.2× 1014 N+/cm2 of dose - the optimum condition, a mutant, S-34, was obtained, which had nearly a 5-fold higher surface and a 13-fold higher of emulsifica-tion activity than the wild type. The surface activity was measured by two methods, namely, a surface tension measuring instrument and a recording of the repulsive circle of the oil film; the emulsification activity was scaled through measuring the separating time of the oil-fermentation mixture. The metabolic acid was determined as methane by means of gas chromatography. 展开更多
关键词 low energy ion beam implantation microbial enhanced oil recovery (MEOR) enterobacteriaceae sp. surface and emulsification activity gas chromatography
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