黑曲霉FS25产β-葡聚糖酶发酵特性的研究*

黑曲霉 (Aspergillusniger) FS2 5产β 葡聚糖酶最适碳源为大麦粉 ,氮源为玉米浆 ;最佳摇瓶发酵配方为大麦粉 6g ,玉米浆 2g ,(NH₄)₂SO₄0.4g ,FeSO₄·7H₂ O 0.01g ,Na₂ HPO₄·3H₂ O 0.1g,CaCO₃0.5g ,MgSO相似文献   

E.aero高产13-丙二醇菌株选育及发酵培养基研究(Ⅰ)

以淡水湖泊泥土中分离出的 30 0多株肠杆菌 (Enterobacter)为出发菌株 ,利用常规筛选方法选出 2株 1 3 丙二醇产生菌 (Enterobacteraerogenes)。经UV、DES、NTG、EMS、LiCl单独及复合诱变 ,选育出一株 (E aero N 56) 1 3 PD高产突变株。通过单因素实验 ,确定了E aero N 56菌株 1 3 PD发酵培养基为 :甘油 90g L ,NH4Cl₁ 50g L     

绿色木霉MJ1产内切β-葡聚糖苷酶的分离纯化及酶学性质

利用KTAUPC-900快速蛋白液相色谱系统(FPLC)从绿色木霉MJ1固体发酵产物中分离纯化出内切β-葡聚糖苷酶。分离纯化后酶的比活力提高了28.6倍,回收率为19.7%。SDS-PAGE后经BIO-RAD凝胶成像系统分析该内切酶的分子量为64.7kD。酶学试验研究表明:该酶的最适反应温度53℃,最适pH为4.2,Lineweaver-Burk法求得动力学参数,K_m和V_max分别为1.230×10^{-2相似文献}   

海枣曲霉β-葡萄糖苷酶的提纯与性质

通过聚乙二醇6000一磷酸钾缓冲液双相分离,Sephadex G—100凝胶过滤、DEAE-Sephadcx A-50及SE-Se phadex C-50离子交换柱层析等提纯步骤,从海枣曲霉(Aspe rgillutphoenlcis)麦麸培养物抽提液中提纯到凝胶电泳均一的β-葡萄糖苷酶。该酶的最适pH5．0,最适温度60℃,在pH 4．0--7．5之间及55℃以下稳定。Ag+及Hg2+对该酶有强烈的抑制作用。用SDS-凝胶电泳法及梯度凝胶电泳法测得该酶均分子量分别为118000及195000薄层凝胶等电聚焦法测得其等电点为pH 3.95。     

产氨短杆菌B1-15-15分段合成法制造5’-肌苷酸及其它核苷酸类物质

产氨短杆菌(Brevibacterium ammoniagenes)B_1-15-15,为野生型,需生物素,对Mn++不敏感菌株,它具有“分段合成”核苷酸的能力,将外源核酸碱基转变为相应的核苷酸类物质。在30℃摇床培养3天后,加入0.3—0.5％的次黄嘌呤继续培养2天,可产生5'-IMP12一16克／升。发酵的适宜条件为：培养基分别灭菌前的pH,糖镁液为5．7(自然pH),磷氮液为7.0;发酵过程中补加尿素控制pH6.7—7.0,尿素总量0.7％左右;玉米浆用量3—4％;Mn++ 50一100微克／升。在30℃培养2天,补加0．4％尿素和0．4%次黄嘌呤,提高温度至37℃培养,可缩短发酵周期至2.5天,5'-IMP产量为9．54克／升。     

金针菇FV088菌株液体培养工艺的研究

通过单因子试验统计分析,优化筛选了适于金针菇（Flammulinavelutipes）FV088的适宜培养基和摇瓶培养条件,结果表明,其适宜的液体培养基组成为：5.0％玉米粉,2．0％鼓皮,0．L％KH₂PO₄,0．05％MgSO₄·7H₂O,10μgVB₁／100ml,50μgVB₂／100ml;适宜的摇瓶培养条件为：培养基的起始pH6．0～7．0,500ml     

变异株B．S．796生产σ淀粉酶工艺条件的研究

从枯草杆菌Bacillus subtilis209出发,选育出B．S．796变异株。该菌在麦芽糖6％,豆粕水解液6—7％, Na₂HPO₄·12H₂OO．8％, (NH₄)₂SO₄ O．4％, CaCl₂ O．2％,NH₄Cl0．15％,pH6．5—7．O的培养基(麦芽糖培养基)中可获得较高的a-淀粉酶活性,在1．5m3发酵罐中试验a-淀粉酶活性平均可达477u／ml(比原菌提高40．6%)。按上法所得发酵液能快速通过板框压滤机,过滤回收率高达95％,提取总收率约为78％。     

微生物发酵稻草生产饲料蛋白培养条件的研究

研究了糙皮侧耳 (Pleurotusostreatus)和康氏木霉 (TrichodermaKoningii)发酵稻草生产饲料蛋白的培养条件。在实验室条件下 ,培养基的基本组成为稻草 80g ,麸皮 2 0g ,(NH₄)₂SO₄2g ,葡萄糖 2g,KH₂ PO₄1g。原料 :水为 1∶3 ,pH5.5～6.0 ,接种量 10%,培养温度28℃～30℃ ,培养周期10d。产物分析结     

微生物发酵生产十一烷1，1 1二羧酸的研究

从热带假丝酵母(Candiada tropicalis)T25—14经过紫外线和亚硝酸的多次诱变,获得4株产十一烷l,11二羧酸(DC₁₃)较多的突变株,其中最优的NP-159株以20％(V／V)正十三烷(nC₁₃)为碳源摇瓶发酵4天,DC₁₃达80g／L左右。在16L罐上,以30％(V／V)nC₁₃发酵6天,DC₁₃高达139g／L,回收残烃后,对nC₁₃的转化率为80％以上。后处理收率为78．9％,DC₁₃的纯度为95．3％。     

海藻酸盐固定化北京丙酸杆菌丙酸发酵的研究

本文报道利用海藻酸钠固定化北京丙酸杆菌,及其丙酸发酵的最适条件。最适海藻酸钠和菌体的起始浓度分别为2％和I00％(w／v)。菌体和海藻酸盐混合滴入CaCl₂：溶液中得到直径为3—4 mm球形颗粒。将固定化细胞放入25ml厌氧管中5 g颗粒/15ml培养基。其成分为(％)：葡萄糖1,酵母膏0．5,CaCI₂0.1。30℃静置培养产生大量的挥发酸,丙酸对乙酸的比例接近10：1。固定化细胞重复利用发酵30次,保持稳定活性65天。     

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.