1,3-丙二醇发酵液的絮凝预处理研究*

研究了天然澄清剂Ⅱ型B组份对1-3-丙二醇发酵液的絮凝预处理效果。首先通过单因素实验和正交实验,确定了影响絮凝的主要因素及其最佳工艺条件:即在pH6.0、用量为0.01g/L、NaCl盐浓为0g/L时,絮凝率可以达到95.97％。然后考察了絮凝预处理对发酵液过滤以及电渗析脱盐的影响,实验结果表明:絮凝预处理能显著加快发酵液中固体微粒的沉降,提高过滤速度,其中絮凝样的滤饼湿基、干基重量分别比对照样增加41.13％、51.88％;絮凝预处理还能加快电渗析脱盐速度,与过滤相结合可以代替离心预处理。     

双极膜电渗析分离发酵液中L-乳酸

采用三室型双极膜电渗析装置将发酵液中的L-乳酸钠转化为L-乳酸。探讨操作电压、流速、进料L-乳酸钠质量浓度等工艺参数对转化过程的影响,考察电渗析过程参数对转化率、物料损失率、电流效率和能耗等技术指标的影响。在最优操作条件下（流速40L／h,电压15V）对2L的100．25g／L乳酸钠发酵液进行分批重复电渗析处理。结果表明：整个过程的转化率为81．22％,损失率为1．5％,能耗为0．81kW·h／kg,电流效率为91．8％,得到的L-乳酸质量浓度可达144．31g／L．电渗析残液补糖后可回到发酵罐中用于发酵生产L-乳酸.     

青霉素酶发酵液的预处理和酶学特性

研究了在发酵液中添加絮凝剂对发酵液进行预处理,对蜡状芽孢杆菌（Bacillus cereus）产生青霉素酶的影响与酶学特性。实验结果表明,发酵液膜处理的难易程度与芽孢释放程度成正相关,在发酵液中添加0．02g／mL自制絮凝剂进行预处理,过滤效率提高10倍,而酶活损失仅5％;酶学特性研究结果表明,该酶最佳反应温度55℃时,酶的最适反应pH值7．0,金属离子锌、锰、镁对酶有激活作用,其浓度为0．25moL／L;酶热稳定性研究结果表明,在75℃下保温30min时,酶活损失85％。该酶在过量青霉素底物下,酶促反应为0级反应。     

赤霉素发酵液的絮凝预处理研究

通过过滤滤饼常数的测定,分析、讨论了用絮凝法预处理赤霉素发酵液的合理性。实践证明,絮凝不仅可以大大改善发酵液的固液分离效果,同时使滤液浓缩后的沉淀量减少了２／３,萃取过程中的乳化现象也得到了明显的改善。     

壳聚糖对嘧啶核苷类新型抗真菌抗生素发酵液絮凝除菌作用的研究

利用天然高分子聚合物壳聚糖为絮凝剂去除抗生素发酵液中的菌体,结果表明:发酵液pH值、絮凝剂用量是影响絮凝效果的主要因素。最佳絮凝条件为pH7.0,絮凝剂用量0.4g/L,温度30℃,此时菌体絮凝率(FR%)可达70%以上。经絮凝预处理后,滤速为处理前的2.5倍,发酵液的效价由700 U/mL提高到860 U/mL。     

红曲多糖液态发酵工艺条件的优化

实验研究红曲多糖的液态发酵条件,得出优化后红曲菌ZKOA发酵工艺条件：蔗糖40g/L,酵母粉4．5g／L,KH2PO4·3H2O3．5∥L．MgSO40．4g／L,植物油2mL／L,接种量8％,种龄30h,发酵液起始pH5．0,发酵时间90h,在此条件下,摇瓶和中试发酵罐中的粗多糖质量浓度分别为7．6g／L和7．34g/L。     

酿酒酵母培养基中主要因素对海藻糖积累的影响

在对实验室保藏菌种Saccharomyces cerevisiae HY01优化前的摇瓶发酵观察的基础上,采用单因子与响应曲面相结合的实验设计方法研究了酿酒酵母培养基中的初始葡萄糖浓度、无机氮源硫酸铵浓度、酵母浸出粉浓度、碳源与无饥氮源的交互作用以及无机盐和微量元素浓度对海藻糖积累的影响。实验证明碳氮源交互作用明显,并得到了以上各因素的最优值,即初始葡萄糖浓度为20g／L,(NH4)2SO4浓度为4．5g／L,酵母浸出粉浓度为5g／L,微量元素溶液5．0ml／L;硫酸镁0．3g／L;磷酸氢二钠3．67g／L;磷酸二氢钾0．76g／L时,酿酒酵母中海藻糖的干重含量可以达到14．74％,比优化前海藻糖的干重含量12．24％提高了20．41％．     

疏水作用层析纯化脂肪酶

报道了以对β-硫酸酯己砜基苯胺（SESA）为活化剂制备疏水作用层析剂方法及其柱层析纯化脂肪酶的工艺条件。实验结果表明：活化剂对-β-硫酸酯己砜基苯胺（SESA）最适用量为1．0g／g湿纸纤维素。笨胺：丙酮比为1：4．以0．2mol／L磷酸缓冲液（pH8.0）=1mol／LNaCl为淋洗剂,以0．2mol／L磷酸缓冲液（pH8．0）＋8％吐温80为洗脱刘纯化脂肪酶具有较好的分辨率,酶活回收率64．0％,比活提高6．70倍。     

粘杆菌素发酵液微滤膜分离处理过程研究

粘杆菌素由于其药性强、残留低、对人畜无害被认为是最安全的畜禽抗生素之一。利用微滤对粘杆菌素发酵液进行预处理,根据发酵液的特性,选择孔径为0．2μm、膜面积为0．06M。的管式陶瓷膜为微滤膜,研究了操作参数的适宜值：压力为0．2MPa,流量为20L／min,在浓缩倍数达到3．5倍时连续两次加入与浓缩液体等量的水,得率为96％。经微滤处理后,滤液的吸光度Abs（470nm）为0．394,N-NH,含量为115mg／100mL,有效地去除了菌体、胶体蛋白及部分色素等,效果优于工业生产中板框过滤滤液的质量标准。     

江西虫草发酵液脱色及其多糖提取分离的优化工艺

通过单因素和正交试验法,优化了江西虫草发酵液脱色的工艺条件。即在提取多糖前,调节发酵液pH值至5,活性炭用量为3g／100mL,在25℃恒温条件下吸附5min后,发酵液脱色率可达到89．6％,发酵液多糖的耗损率仅为10．7％。在此基础上,采用正交试验法。对发酵液多糖提取工艺进行了优化。利用优化后的工艺,即经脱色和去蛋白后发酵液滤液浓缩至其总体积的1／7,加入乙醇,终浓度为80％,醇析16h,发酵液多糖的得率可达到0．38g／L。     

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     

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.     

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.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

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).     

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.