保加利亚乳杆菌微胶囊化工艺研究

目的制备保加利亚乳杆菌微胶囊,提高菌株的酸、热耐受性及降低菌体的分离成本。方法以保加利亚乳杆菌(Lactobacillus bulgaricus)为研究对象,海藻酸钠(SA)为壳材、CaCl2为固化剂,制备保加利亚乳杆菌微胶囊;包埋率、颗粒平均化程度、机械强度等为考核指标,研究保加利亚乳杆菌微胶囊化的工艺。结果当海藻酸钠浓度为0.75%、CaCl2浓度为3%、电压为600V、泵速为1.96mL/min、震动频率为80Hz时,微胶囊化包埋效果最佳,经固定化后的菌微胶囊保持了良好的保加利亚乳杆菌的活性,微囊化保加利亚乳杆菌经过2次连续发酵后的产酸量分别达到59.4g/L和55.8g/L。结论本研究为工业化生产乳酸提供了一条具有经济价值的途径。     

增强微胶囊在血液中稳定性的研究

目的:通过改进成膜工艺,减少血液中HCO3-对海藻酸钠-ε-聚赖氨酸(ε-AP)微胶囊稳定性的影响,从而增强ε-AP微胶囊在血液中的稳定性,使其能够应用于生物人工肝血浆/血液灌注。方法:改进成膜工艺:在成膜液中添加10 mmol/L的Na HCO3并增加ε-聚赖氨酸反应浓度来制备ε-AP微胶囊,用膨胀度表征其机械强度,荧光标记的牛血清白蛋白(FITC-BSA)检测其通透性能,并以微胶囊的膨胀度变化作为衡量指标,考察微胶囊在Na HCO3溶液和血清中的稳定性。结果:改进成膜工艺制备的ε-AP微胶囊与常规条件制备的微胶囊具有接近的机械强度和通透性;改进成膜工艺能够增强的ε-AP微胶囊在Na HCO3溶液和血清中的稳定性;常规条件制备的ε-AP微胶囊在血清中膨胀度增加了约560%,而改进成膜工艺制备的微胶囊膨胀度仅增加160%,其稳定性显著增强。结论:改进成膜工艺能够增强ε-AP微胶囊在血液中的稳定性。     

海藻酸钙凝胶包埋法制备固定化小球藻

采用海藻酸钙凝胶包埋法对普通小球藻进行固定化,考察了海藻酸钠浓度、Ca Cl2浓度、胶球直径和胶球培养密度对固定化小球藻生长的影响,比较了游离和固定化小球藻细胞的生长特性,并测试了固定化小球藻的连续培养性能。结果表明,小球藻适宜的固定化条件为:海藻酸钠浓度2%(W/V)、Ca Cl2浓度1.5%(W/V)、凝胶球直径3 mm、凝胶球培养密度200粒/100 m L;与游离态小球藻相比,固定化小球藻的生长周期较长,在对数期后期和稳定期的生长态势优于游离态细胞,并可实现重复循环利用;连续培养实验显示,在优化条件下制备的固定化小球藻可连续使用200 h左右,有望用于生物催化和生物转化中的连续反应体系。     

SA/NaCS-PDMDAAC微胶囊固定化酵母细胞合成胞苷三磷酸

通过海藻酸钠/纤维素硫酸钠-聚二甲基二烯丙基氯化铵(SA/NaCS-PDMDAAC)微胶囊固定化酵母细胞将胞苷一磷酸(CMP)转化为胞苷三磷酸(CTP),考察了各种因素条件对CTP转化率的影响,以提高CTP的转化率.通过考察分批补料添加葡萄糖,固定化酵母量,CMP浓度等以达到提高CTP转化率的要求.结果在250 mL锥...     

酪氨酸酚裂解酶的固定化与转化条件的优化

以欧文氏菌(Erwinia herbicola)来源的酪氨酸酚裂解酶的重组大肠埃希菌Escherichia coli BL21为研究对象,研究固定化大肠埃希菌生产L-酪氨酸的条件。以海藻酸钠为载体,采用单因素实验分别考察了载体材料、明胶浓度、反应时间、苯酚浓度和辅助剂(二氧化硅、硅藻土和碳酸钙)等因素对L-酪氨酸生产的影响,发现明胶浓度、反应时间、苯酚和碳酸钙等因素的影响较为显著,进而通过正交实验探索最优条件。结果表明,生产L-酪氨酸的最优条件:载体为4%海藻酸钠与6%明胶的混合载体,苯酚浓度0.08 mol/L,反应时间8 h,于载体中添加0.6%碳酸钙。此条件下,连续反应9次后L-酪氨酸的产量达到64.5 g/L,比优化前提高了451.3%。     

乙二醇缩水甘油醚交联海藻酸钠-羧甲基纤维素钠固定化脂肪酶

以海藻酸钠、羧甲基纤维素钠(CMC)为载体,分别以乙二醇缩水甘油醚(EGDE)和戊二醛为交联剂,采用包埋交联法对脂肪酶进行固定化,结果显示EGDE的交联效果要优于戊二醛,添加EGDE的固定化酶酶活最好。得到制备固定化酶的最优方案为海藻酸钠2.5%,CMC浓度1.5%,给酶量800U/ml复配载体,氯化钙5%,以0.02%的EGDE交联固定30min,由此制备得到酶活约为380 U/g的固定化酶,酶活收率约为50.09%。固定化酶的最适反应p H为8.5,比游离酶增大0.5个单位;最适反应温度是45℃,比游离酶提高5℃;耐热性能变好,且重复使用7次后仍能保持60%左右的相对酶酶活。     

果胶酶固定化方法的研究

用海藻酸钠、二醋酸纤维、明胶分别作为固定化果胶酶的载体,研究比较载体的用量、交联剂的浓度、用酶量、制备的ｐＨ。结果表明,选择１５％浓度的明胶为载体,５％浓度的戊二醛为交联剂,用酶量５％,在ｐＨ３．５条件下制备固定化果胶酶,其酶活力回收率可达６７．７４％,重复回收使用１０次后,酶活力还可保留８０％以上,是果胶酶固定化的一种较好的方法。     

固定化葡萄糖异构酶的研究

采用明胶包埋经热固定处理的链霉菌细胞,再用戊二醛交联的复合法制备固定化葡酶糠异构酶。选择了合适的包埋配比和戊二醛交联的最适条件。确定了制备固定化酶的工艺条件。对固定化酶的若干性质进行了试验研究,选择了一个较理想的转化条件,在此基础上进行了多次固定床反应器的连续转化试验(干固定化酶重量为1 kg),以40—44%(w/w)的双酶法液体葡萄糖为底物,在5 ×10~-3MgSO_4,5×10~-3Na_2SO_8,pH7.2.64℃±1℃的条件下,固定化葡萄糖异构酶的半衰期为30天以上,56—60天酶活保留原来的25%。每公斤干固定化酶可转化绝干葡萄糖2吨左右(转化率     

基于海藻酸钠羟基改性的MPEG原位共价修饰微胶囊及抗蛋白性能

目的:通过对海藻酸钠链段羟基位点改性制备甲氧基聚乙二醇(MPEG)原位共价修饰的海藻酸钠/壳聚糖(AC)微胶囊,在保证MPEG修饰微胶囊机械强度不受影响的基础上,有效提高表面MPEG修饰密度,实现兼具良好机械稳定性及抗蛋白性能的微胶囊制备方法。方法:利用溴化氰对海藻酸钠羟基进行活化并将末端氨基的点击化学linker(BAT)接枝在主链上进而制备MPEG原位共价修饰微囊A_(B(OH))CP_N,用球磨法表征微囊机械强度,用Ig G和Fgn为模型考察微囊表面抗蛋白吸附性能,以L929细胞在其二维模拟平板膜上的黏附情况作为衡量指标,考察MPEG修饰微胶囊表面细胞粘附情况,并最终通过体内移植考察MPEG修饰微囊的生物相容性。结果:基于海藻酸钠羟基位点的MPEG原位共价修饰微胶囊能够实现与常规条件制备的微胶囊接近的机械强度;同时与对照组相比Ig G吸附量降低87.4%,Fgn吸附量降低75.5%,实现了良好的抗蛋白吸附性能;二维模拟平板膜表面L929细胞粘附情况显著改善,细胞粘附数与对照组相比降低了76.9%;体内移植结果证明MPEG修饰微囊细胞粘附极少,微囊与纤维层分离明显。结论:基于海藻酸钠羟基位点的MPEG原位修饰能够实现兼具良好机械稳定性及抗蛋白吸附性能的微胶囊。     

果胶酶固定化方法的研究

用海藻酸钠、二醋酸纤维、明胶分别作为固定化果胶酶的载体,研究比较载体的用量、交联剂的浓度、用酶量、制备的ｐＨ。结果表明,选择１５％浓度的明胶为载体,５％浓度的戊二醛为交联剂,用酶量５％,在ｐＨ３．５条件下制备固定化果胶酶,其酶活力回收率可达６７．７４％,重复回收使用１０次后,酶活力还可保留８０％以上,是果胶酶固定化的一种较好的方法。     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).