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.

奶牛源鼠李糖乳杆菌的^(12)C^(6+)重离子束诱变选育

本研究利用中科院重离子加速器释放的^(12)C^(6+)重离子束作为辐射诱变源,以酸斑值(H^(12)C^(6+))和抑菌圈值为指标,对鼠李糖乳杆菌JF12-1进行功能性诱变。通过致死率和正负突变率确定诱变的最佳辐照剂量;对最佳辐照剂量下的突变菌株利用酸斑法进行初筛,抑菌圈法复筛,而后通过连续传代之后检测乳酸含量变化来测定遗传稳定性,并对遗传稳定菌株进行16S rDNA测序,定位其突变位点。结果显示辐照剂量为300 Gy时,致死率为79.86%,正突变率为30.33%,负突变率为5.38%,确定为最佳诱变剂量;酸斑法初筛最佳诱变剂量下的突变菌株,得到20株H^(12)C^(6+)值较原始野生菌株提高25%以上的突变株;抑菌法复筛得到8株体外抑菌性较原始野生菌株提高15%以上的菌株;遗传稳定性测定发现这8株突变乳酸菌株产乳酸稳定性良好;16S rDNA测序发现原始野生型菌株JF12-1的可能突变位点不在16S rRNA基因上,促使其产酸和抑菌性能增强的突变位点可能发生在其他基因区段。利用^(12)C^(6+)重离子束成功诱变选育出了高产乳酸及体外抑菌性优良的功能性鼠李糖乳杆菌稳定株,为下一步深入开发该菌株提供了较好的理论基础和应用依据。

^(12)C^(6+)离子束放射治疗脑胶质瘤的有效性

目的探究不同剂量^(12)C^(6+)离子束辐照大鼠C6脑胶质瘤的肿瘤局部控制效果,为^(12)C^(6+)离子束治疗脑胶质瘤提供试验依据。方法建立42只雄性SD大鼠C6脑胶质瘤模型,辐照前随机选取3只荷瘤鼠作为对照,其余随机分为0 Gy组(n=15)、1.0 Gy组(n=12)及2.0 Gy组(n=12),每组前期预试验随机选取6只进行生存分析。不同剂量^(12)C^(6+)离子束辐照前及辐照后第7、14天进行CT能谱成像增强扫描,每组于辐照后各时间点随机选取3只荷瘤鼠心脏灌流采集脑组织苏木精-伊红染色和Ki-67、CD34免疫组织化学染色。结果0 Gy组与2.0 Gy组荷瘤鼠生存期差异有显著统计学意义(P<0.05)。2.0 Gy组辐照第7、14天肿瘤实体65 keV单能量CT值、碘浓度逐渐降低,1.0 Gy组辐照第14天明显降低,且均与0 Gy组差异有显著统计学意义(P<0.05)。2.0 Gy组辐照第7、14天肿瘤实体Ki-67增殖指数及CD34阳性细胞表达量逐渐降低,1.0 Gy组辐照第14天显著降低,且各组Ki-67增殖指数及CD34阳性细胞表达量与65 keV单能量CT值、碘浓度具有良好的相关性(r>0.7,P<0.05)。结论^(12)C^(6+)离子束辐照大鼠C6脑胶质瘤能够明显抑制肿瘤生长和侵袭。

^(12)C^(6+)重离子突变藻株混合处理黑臭水性能研究

微藻混合培养可以在高效去除水质污染物的同时,积累更多生物量及油脂,促进微藻生物质资源化利用。然而存在菌种间相互竞争导致处理效果不佳的问题,故找出微藻藻种间最佳协同组合至关重要。该文通过将一株可在黑臭水中快速生长的原壳藻Auxenochlorella protothecoides,分别与污水处理中常用的普通小球藻Chlorella vulgaris、蛋白核小球藻Chlorella pyrenoidosa和斜生栅藻Scenedesmus bliquus进行不同比例混合培养,结果显示4种微藻1∶1∶1∶1混合培养为最佳组合。为进一步提升水中污染物去除效率,促进资源化利用水平,将经C重离子辐照诱变后的4种藻株按相同比例混合培养进行性能强化,结果表明:相比初始藻株组合,^(12)C^(6+)重离子突变藻株组合COD、NH_(4)^(+)-N及TP最大去除率分别提高了12.12%、11.01%及22.12%,其最大比生长速率和油脂增长率分别提高了63.03%和79.71%。

Influence of ^(12)C^(6+) ion irradiation on mutant avermitilis

The effects of 12C＋6 ion irradiation on colony morphology and mycelia morphology, as well as on mutation rate have been studied in the B1a high-product strains （ZJAV-Y1-203） mutated by heavy ion irradiation and compared with that in the original strain （ZJAV-A-1）. After irradiating the rate of a straw hat colony type having a high ability of producing B1a in ZJAV-Y1-203 strains was higher than that found in ZJAV-A-1 strains. When strains were cultured in a liquid medium for 24 hours, the mycelium becoming thinner could be observed in all of the irradiated ZJAV- Y1-203 groups, but only in the ZJAV-A-1 groups irradiated at the dose of 50 Gy or more. The early growth of mycelium was inhibited in the ZJAV- Y1-203 group irradiated with a high dose. The highest positive mutation rate （23.5%） of ZJAV - Y1 - 203 was reached at the lower dose of 30 Gy while the highest positive mutation rate of 34.2% in ZJAV-A-1 appeared at 50 Gy. These results indicate that the effects of heavy ion irradiation still exist even in the mutated Streptomyces avermitilis, and only the dose is lower and the effects not so strong compared with the one that is first irradiated with optimized heavy ion doses. This is evidence of the one directional mutation being controlled by many more factors in a organism.

重离子束^(12)C^(6+)照射人离体血建立淋巴细胞微核的剂量-效应曲线

目的 研究建立重离子束1 2 C6 + 照射人离体血诱发淋巴细胞微核的剂量 效应曲线。方法 用地面加速器产生的重离子1 2 C6 + (平均LET为 36 70keV μm) ,不同吸收剂量、不同吸收剂量率照射离体人血 ,用CB微核法观察双核淋巴细胞中的微核。结果 在 0～ 6Gy吸收剂量范围内 ,淋巴细胞微核率随吸收剂量的增加而增加 ,拟合的最佳方程为Y =6 6 5 0 9×D0 .85。结论 1 2 C6 + 照射人离体血诱发淋巴细胞微核在 0～ 6Gy吸收剂量范围内呈幂函数关系。