L-天冬酰胺酶工程菌株培养条件及稳定性

L-天冬酰胺酶工程菌株的酶活和表达水平受菌体生物量和诱导时间的影响。在生物量Ａ６００03×１０左右,热诱导4h酶活力和表达水平可达到较高水平。葡萄糖对酶的生成有阻遏作用,当葡萄糖浓度大于025%时,对工程菌酶的合成造成阻遏。确定了工程菌培养的培养基、pH值、接种量等因素。重组质粒pASN在\%E.coli\% JM105,TG1和AS1357等宿主菌中具有很好的稳定性,工程菌培养50代以上重组质粒保留90%以上,在LB和M\|3培养基中也较稳定。     

剩余活性污泥完全资源化利用微生物集成技术

剩余活性污泥完全资源化利用微生物集成技术包括: 使用土著PHA合成菌回注法驯化并发酵活性污泥, 生产生物降解材料聚羟基脂肪酸酯(PHA); 采用土著嗜酸性氧化亚铁硫杆菌和氧化硫硫杆菌进行生物淋滤, 去除重金属; 以解磷菌和解钾菌为菌种, 进行固态发酵, 生产生物菌肥。结果表明, 500 L中试PHA占挥发性悬浮固体的20%以上; 重金属含量达到国家排放要求; 生物菌肥中活菌数大于1×108 个/g以上。实现了剩余活性污泥的近零排放。     

Nanoparticle self-assembly by a highly stable recombinant spider wrapping silk protein subunit

Artificial spider silk proteins may form fibers with exceptional strength and elasticity. Wrapping silk, or aciniform silk, is the toughest of the spider silks, and has a very different protein composition than other spider silks. Here, we present the characterization of an aciniform protein (AcSp1) subunit named W₁, consisting of one AcSp1 199 residue repeat unit from Argiope trifasciata. The structural integrity of recombinant W₁ is demonstrated in a variety of buffer conditions and time points. Furthermore, we show that W₁ has a high thermal stability with reversible denaturation at ∼71 °C and forms self-assembled nanoparticle in near-physiological conditions. W₁ therefore represents a highly stable and structurally robust module for protein-based nanoparticle formation.     

禽致病性大肠杆菌毒力基因多重PCR方法的建立和应用

【目的】建立禽致病性大肠杆菌(Avian pathogenic Escherichia coli,APEC)黏附相关基因、侵袭及毒素相关基因、抗血清存活相关基因及铁转运相关基因的多重PCR方法,实现禽致病性大肠杆菌毒力基因的简便、快速检测。【方法】根据GenBank公布的基因序列,设计合成18对特异性引物,通过条件优化,建立四组多重PCR体系,并通过模板倍比稀释检测各组多重PCR的灵敏性。利用多重PCR检测100株APEC毒力基因的分布,验证多重PCR方法的可行性。【结果】根据PCR扩增片段大小判定,上述四组多重PCR体系均能同时扩增出该组中的各个毒力基因,且灵敏度分别为:103CFU、103CFU、105CFU、105CFU细菌和1ng、1ng、10ng、10ng DNA。100株APEC的毒力因子检测结果显示,多重PCR和单基因PCR结果一致。【结论】建立的四组多重PCR方法能够简便、快速地检测禽致病性大肠杆菌的毒力基因,可用于毒力基因的鉴定以及流行病学调查。     

脂肪酶产生菌的筛选及鉴定研究

为寻找合适的产脂肪酶野生菌,以期能高效的催化合成生物柴油。通过添加橄榄油作为惟一碳源进行富集培养,然后以透明圈平板筛选法从油污土壤样品中成功地筛选到了一株酶活力值为10.12U/ml产脂肪酶菌株。通过对该菌株表型、生理生化特征分析及16S rRNA部分序列的系统进化发育分析鉴定该菌为芽胞杆菌属,定名为BacilluspumilusB2。     

用核酸斑点杂交法比较油桐尺蠖核型多角体病毒与某些昆虫杆状病毒的同源性

有关核型多角体病毒基因同源性的研究报道不多,结果也不甚一致。目前,国内外普遍用SDS-PAGE法分析昆虫杆状病毒结构多肽,以限制性内切酶谱法测定基因组大小,借此区分来自不同宿主的病毒株,和基因组密切相关     

MD Simulations and first principles to evaluate the role of binary Fe–V alloys layer on the radiation resistance in the alpha-iron

Radiation damage in reactor materials caused by the collision of the fast neutrons has a great impact on the reliability and safety of nuclear reactors. The element vanadium has attracted interest in many fields due to its advantageous properties in alloys. Thus, molecular dynamics simulation (MD) and first-principles calculation have been executed here to explore the radiation-resistant properties of five materials adding a layer in the bulk (pure iron and four types of Fe–V alloys containing 10%-40% V). The following results were inferred from these simulations. Firstly, the number of Frenkel pairs (FPs) at the stable quenching stage in the bulk decreases when the Fe–V alloy is added as an anti-radiation layer to the bulk. These benefits are evident for the Fe₈₀V₂₀ and alloy layers with more vanadium. The main reason is that the Fe–V binding energy is greater than the Fe-Fe binding energy, which can make the Primary Knock-On atom (PKA) lose more energy at the Fe–V alloy layer. Secondly, the average value of point-defect, cluster and defect clustered fractions in the bulk of Fe–V alloy is smaller than that in the pure iron at the stable quenching stage, especially for the Fe₈₀V₂₀ alloy.