氮离子束注入诱变选育胞外多糖高产菌株

采用氮离子束注入胞外多糖产生菌进行诱变处理来获得胞外多糖高产菌株。氮离子注入过程采用的能量为10 keV,剂量为60×1014–140×1014cm-2。根据其存活率及突变率确定最佳的注入剂量。结果表明:菌株存活率曲线遵循氮离子注入生物效应的"马鞍型曲线",当注入剂量为120×1014cm-2时,获得了最佳的诱变效果。通过筛选和连续5次传代,获得具有良好稳定性的突变株,其多糖产量达到3.29 g/L,较出发菌株提高了19.20%,且发酵周期缩短了6 h。     

氮离子注入柠檬酸生产菌的诱变选育

用15keV氮离子注入对柠檬酸生产菌进行诱变选育,对该低能离子与微生物间的作用规律进行了初步探索,并获得三株高产突变菌株。其中,以木薯为底物的突变菌株的柠檬酸产率提高14．2％,以玉米粉为底物的两株突变菌株的柠檬酸产率分别提高15．9％和17．0％,经多次传代实验表明,这三种突变菌株均有较好遗传稳定性。     

离子注入诱变选育肌苷高产菌株

以肌苷产生菌——枯草芽孢杆菌（Bacillus subtilis HSD06）为出发菌株,经不同剂量的旷离子束注入处理,定向选育磺胺胍抗性提高的突变株。获得磺胺胍突变株的最佳照射剂量为3×10^15cm^2。从528个抗性提高的菌落中筛选获得B11和B13肌苷高产菌株,其摇瓶发酵水平肌苷产量为14．83g／L和14．38gm,分别比出发菌株提高了16．3％和12．8％。     

重离子束辐照选育高产植物乳酸菌

采用重离子束~(12)C~(6+)对乳酸菌出发菌株JTL进行辐照选育。确定吸收剂量300 Gy时最优,在该吸收剂量下,出发菌种的正突变率和致死率均达到最高,分别为34.4%、80%。通过酸斑法初筛和发酵复筛法,选育出高产酸的3株突变菌株(JTL2、JTL3、JTL5),其发酵液中乳酸含量比出发菌株JTL提高了41.29%~49.64%。同时,经过传代实验证实,3株菌株具有良好的遗传稳定性。研究表明,利用重离子束~(12)C~(6+)辐照处理乳酸菌可以得到高产酸的突变菌株,诱变效果显著。     

重离子辐照育种对西蓝花幼苗生长及生理特性的影响

西蓝花（Brassica oleracea var. italica）是我国重要的蔬菜作物之一,其种子主要源于进口,亟需开发属于我国的创新型品种。为探究高能重离子束对西蓝花的当代生物学效应,本研究采用碳离子束辐照西蓝花种子,检测其幼苗期的生长指标、抗氧化酶活性、光合指标和叶绿素荧光等参数。结果表明：100～500 Gy的辐照对种子的萌发没有显著影响,600 Gy显著抑制其萌发。100～600 Gy辐照后根长、芽长、苗高、叶面积总体上随剂量增加而降低。碳离子束辐照西蓝花的半致死剂量（Median lethal dose, LD50）为415.89 Gy,使根长减半的剂量为495.12 Gy。辐照后幼苗的超氧化物歧化酶（Superoxide dismutase, SOD）和过氧化物酶（Peroxidase, POD）活性均高于对照,过氧化氢酶（Catalase,CAT）的活性低于对照,400 Gy辐照后丙二醛（Malondialdehyde,MDA）含量显著升高。随吸收剂量的增加光合色素（叶绿素a、叶绿素b和类胡萝卜素）呈现先升高再降低的趋势,最高值出现在300 Gy处。净光合作用、蒸腾速...     

重离子辐照冬小麦诱变效应的研究

利用3.2—75MeV/u4个能量、2×108—12×108cm–24个剂量的O和C重离子处理3个冬小麦品种,1612研究其诱变效应。结果表明,M1代的生物损伤随剂量的增加而加大;8MeV/u能量的损伤要比高能75MeV/u时大;8MeV/u较易出现在高能75MeV/u离子和γ辐射中未见的条状叶绿素缺失损伤,此结果未见相关报导。M2代诱变效果显著,突变谱宽,有益突变(早熟、矮杆、穗形)频率明显高于γ射线,且较易诱发早抽穗性状变异。     

重离子辐照对红酵母的诱变作用

应用重离子加速器的50MeV／u^12C^6 重离子对胡萝卜素生产菌-红酵母(Rhodotorula RY Strain)进行辐照处理,经酵母发酵实验,发现50MeV／u^12C^6 重离子对胡萝卜素生产菌-红酵母具有诱变作用。初步筛选到了胡萝卜素产量有变化的辐照变异菌株,并对这些辐照变异菌株进行了RFLP(限制性片段长度多态性)和RAPD(随机扩增DNA多态性)分析,这些工作为工业上利用重离子对胡萝卜素生产菌进行诱变育种展现了新的前景。     

重离子活化分析

我所曾采用重离子活化法测定空气中的铅,灵敏度达10~(-9)克。应用重离子束的特点是对某一靶核能产生更多的核反应和获得较高的产率来探测更低含量的元素,从而提高了方法的灵敏度,如测定氮,采用10MeV质子,通过核反应~(14)N(P,α)~(11)C,探测极限为0.001ppm,而采用13.5MeV ~9Be,通过核反应~(14)(~9Be,αn)~(13)F,探测极限即可提高到0.0005ppm。轻粒子活     

离子束辐照结合组织培养在植物诱变中的研究进展

简述了植物组织培养方法与离子束辐射相结合这一新诱变技术的研究进展,从原理、操作步骤、分子机理等诸方面对该方法进行了阐释.该诱变技术具备传统辐射诱变技术所不具备的优势,从而能够为利用无性繁殖技术进行后代繁衍的植物提供新的育种思路.与此同时,使用该方法还能够开展植物组织细胞的传能线密度(Linear energy transfer,LET)生物学效应的研究,从理论上及实践上进一步优化该技术.     

A high-throughput screening method for breeding Aspergillus niger with 12C6+ ion beam-improved cellulase

In this study,a high-throughput screening method was established through the 24-square deep-well microliter plate(MTP) fermentation and micro-plate detection for large-scale screening of the mutants.It was suitable for screening a large number of mutants and improving the breeding efficiency after heavy-ion beam irradiation.Seventeen strains showed higher cellulase activity compared with the initial strain after the screening of plate and MTP fermentation.The filter paper activity and β-glucosidase activity of Aspergillus niger H11201 had increased 38.74 and 63.23%separately compared with A.niger H11 by shaking flask fermentation,and it was genetically stable after being passaged to nine generations.The results indicate that the high-throughput screening method can be used for the quick breeding of A.niger with high cellulase activity.     

重离子束对牧草的改良

采用80MeV／u^20Ne^10 离子束贯穿处理豆科与禾本科牧草种子,大田和根尖细胞观测的结果表明,随着贯穿剂量的增加,幼苗生长明显减弱,呈负相关性。而染色体畸变率和微核率随剂量的增加而显著增加,呈正相关性。同时,从大田长势来看,禾本科牧草比豆科牧草对重离子辐射敏感性强,禾本科牧草适宜剂量为20-30Gy,豆科牧草为150Gy。     

重离子束辐照细胞研究的文献计量学分析

应用文献计量学方法和相应的应用软件,借助Web of Science平台对重离子束辐照细胞这一研究主题的相关文献、作者、期刊、机构以及关键词进行定量和系统考察。结果显示,重离子束辐照细胞研究在1990年之后日益活跃并深入;不同品质的重离子束辐照诱导不同类型细胞会产生不同的生物学效应、旁观者效应及其机制、重离子束辐照细胞生物学效应评估模型、重离子束治疗癌症过程中辐照品质选择与控制模型以及相应的计算机程序是该研究主题的重要内容;引入特定指数推测所得该研究主题重要学术期刊与Nature,Proceedings of the National Academy of Sciences of the United States of America,Cancer Research等期刊之间有较高的共被引频次,表明更多科学前沿的突破性成果和思路应用于该主题研究中;此外,该研究主要集中于少数国家、少数机构、少数作者,并且合作相对较少。     

Mutant breeding of Aspergillus niger irradiated by ~(12)C~(6+) for hyper citric acid

In this study,strains of Aspergillus niger 4# for hyper citric acid were irradiated to different doses by80 MeV/u ~(12)C~(6+) ion beams.Seven mutant strains showed marked citric acid over-production records and faster productivity than initial Aspergillus niger 4# by shaking flash fermentation.The maximum product yield was 132.8 gL~(-1)(the H4002 strain) being a 8.8%increase to the initial strain.The scale-up experiment was carried out in a 100 L bioreactor.The mutant H4002 can accumulate 187gL~(-1) product yield of citric acid from starch liquefying supernatant.The productivity of citric acid was 2.75gL~(-1) h~(-1).So,the mutant H4002possesses rapid sugar katabolism for producing citric acid.Meanwhile,the pellet morphology kept compact and round during the whole submerged fermentation,which was suited to produce citric acid.The results indicate that mutant H4002 has potential ability to produce citric acid rapidly.     

Development of function-graded proton exchange membrane for PEFC using heavy ion beam irradiation

The graded energy deposition of heavy ion beam irradiation to polymeric materials was utilized to synthesize a novel proton exchange membrane (PEM) with the graded density of sulfonic acid groups toward the thickness direction. Stacked Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) films were irradiated by Xe⁵⁴⁺ ion beam with the energy of 6 MeV/u under a vacuum condition. The induced trapped radicals by the irradiation were measured by electron spin resonance (ESR) spectroscopy. Irradiated films were grafted with styrene monomer and then sulfonated. X-ray photo-electron spectroscopy (XPS) spectra showed that the densities of sulfonic acid groups were controlled for injection “Surface” and transmit “Back” sides of the fabricated PEM. The membrane electrode assembly (MEA) fabricated by the function-graded PEM showed improved fuel cell performance in terms of voltage stability. It was expected that the function-graded PEM could control the graded concentration of sulfonic acid groups in PEM.     

重离子束的Bragg峰定位于麦粒的自由基探针技术

为了实现定点定位诱变，提出了一种利用ＥＳＲ波谱术对离子束Ｂｒａｇｇ峰在麦粒中的定位方法，即自由基探针技术，采用该技术有效地测定出２１ＭｅＶ／ｕ氮离子束的Ｂｒａｇｇ峰位于小麦胚部，注入深度不超过１．０±０．２ｍｍ，而４８ＭｅＶ／ｕ氮离子束贯穿全麦粒，不能实现定点定位诱变。     

~(12)C离子束辐照对酵母发酵能力的影响

利用100MeV/u的12C6+离子束辐照酵母Saccharomyces cerevsiea YY,选育出一株高产突变菌株C03A,考察C03A发酵过程中不同温度、pH、糖汁浓度对发酵的影响。通过正交实验确定最佳发酵条件为:糖汁浓度24%、温度35℃、pH5.0。在10L发酵罐实验中,C03A发酵速率相对原始菌株高,36h发酵完全,比原始菌株缩短12h;发酵产酒率达到13.2%(V/V),比原始菌株高1.6%(V/V)。     

Studies on Mutation Breeding of High-Yielding Xylanase Strains by Low-Energy Ion Beam Implantation

As a new mutagenetic method, low-energy ion implantation has been used widely in many research areas in recent years. In order to obtain some industrial strains with high xylanase yield, the wild type strain Aspergillus niger A3 was mutated by means of nitrogen ions implantation （10 keV, 2.6× 10^14 ～ 1.56 × 10^15 ions/cm^2） and a mutant N212 was isolated subsequently. However, it was found that the initial screening means of the high-yielding xylanase strains such as transparent halos was unfit for first screening. Compared with that of the wild type strain, xylanase production of the mutant N212 was increased from 320 IU/ml to 610 IU/ml, and the optimum fermentation temperature was increased from 28 ℃ to 30 ℃.