高产碱性果胶酶菌株的育种及其发酵条件的研究

以克劳氏芽孢杆茵(Bacillus clausii)S-4为出发菌株,经紫外诱变育种和固态发酵条件的选育,得到产碱性果胶酶较高的新茵株N-10,并研究了其固态发酵条件和部分酶学性质.结果表明,以甜菜渣为碳源和酶的诱导物以及棉粕作为氮源较适宜.较优的固态发酵条件为:甜菜渣5g,棉粕0.125 g,麦芽糖0.1 g,KH2PO40.0075 g,Na2CO30.15 g,水12.5 mL,种龄24 h,接种量2mL,发酵温度40℃,发酵时间84 h;酶产率可达4780 u/g(干甜菜渣),较菌株S-4提高108%.该酶的最适pH 10,最适温度55℃;分别在pH 7.5～9.5和30～40℃范围内较稳定;Ca2 、Mg2 、Fe2 对酶活有明显激活作用,Cu2 、Zn2 对酶活有强烈抑制活作用.     

黑曲霉GD-6纤维素酶液体发酵条件的研究

采用黑曲霉 (Aspergillusniger)GD 6液体发酵生产纤维素酶 ,研究了碳源、氮源、培养基起始 pH值、接种量、摇床转速、通气量对该菌株产纤维素酶活力的影响。结果表明 ,GD 6的最适发酵温度为 2 8～ 3 0℃ ,产酶pH为 5 .5～ 6.0 ,摇床最适转速为 1 5 0r/min ,最佳接种量为 1 0 %。在以 6.0 %稻草粉为碳源、1 %豆饼粉为氮源时产酶活力最高。在最适培养条件下 ,发酵周期为 1 2 0h,发酵液中CMC酶活为 1 88.6U/mL ,FP酶活为 2 7.0U/mL。     

酶水解菊芋糖浆发酵生产琥珀酸的初步研究

用产菊粉酶的一株黑曲霉菌株进行产酶发酵条件和水解条件研究,在30℃,pH 6.0,摇床转速200 r/min,发酵时间为3 d的最适产酶条件下,酶活可以达到45.9 U/mL.以总糖含量为85.2 g/L的菊芋粉为初始底物,最适酶水解条件为温度50℃,加黑曲霉培养液的量为10%(v/v),水解12 h后,水解率达到99.6%.用此酶解液在5 L搅拌发酵罐中进行琥珀酸发酵,初始还原糖浓度53.5 g/L,36 h发酵产琥珀酸43.8 g/L,琥珀酸产率0.83 g/g,糖利用率99.0%,琥珀酸生产强度1.22 g/(L·h).     

黑色葡萄状穗霉S607耐碱性纤维素酶发酵条件的研究

研究了耐碱性纤维素酶生产菌株黑色葡萄状穗霉S6 0 7(StachybotrysatraS6 0 7)的产酶条件。结果表明 ,S6 0 7的最适生长和产酶 pH为 7.0 ,最适产酶温度为 2 8℃ ,摇床最适转速为 180r/min。在以 2 .0 %纤维素粉和 2 .5 %的麸皮作为碳源时产酶最高 ,添加含 (NH4 ) 2 SO4 、尿素和蛋白胨的复合氮源对生长和产酶有明显的促进作用。在最适培养条件下 ,发酵周期为 4～ 5d ,发酵液中CMC酶活为 2 .12IU /mL ,FP酶活为 1.0 3IU /mL ,β 葡萄糖苷酶活为 0 .86IU /mL。     

蚀木链霉菌KX6耐热内切葡聚糖酶的产生及酶学性质研究

从堆肥中筛选到一株产耐热内切葡聚糖酶的放线菌菌株,通过形态观察和16S rRNA序列分析,鉴定为蚀木链霉菌(Streptomyces Xylophagus)。实验中对其产酶的液态发酵条件进行了研究,碳源为1%（w/v）羧甲基纤维素钠,氮源为1%（w/v）豆粕粉,250ml三角瓶30 %装液量,接种量为2%,培养基初始pH为8.0,培养温度为40℃,200r/min培养48h后,发酵液中内切葡聚糖酶活达到0.538IU/ml。该酶的最适作用温度和pH分别为50℃和7.0,50℃下酶活保持1 h不变,60℃保温1h,仍有60%的原酶活性,pH为6.0~7.0酶活稳定,该酶属于一种耐热的中性内切葡聚糖酶。     

Aspergillus sp.脂肪酶发酵条件优化及酶学性质的研究

作者为了得到一种热稳定性较好的脂肪酶新酶种,通过研究分离白极端环境的Aspergillus sp．的最佳产酶条件及其所产脂肪酶的酶学性质,得出了该菌产酶的最佳发酵条件为：以1％黄豆饼粉为氮源、0．2％玉米淀粉为碳源,1．5％橄榄油为诱导物,起始pH6．0左右。装量10mL（250mL三角瓶。摇瓶转速180r／min）、发酵时间为96h。在最佳发酵条件下可得最大发酵酶活36U/mL。Aspergillus sp．所产的脂肪酶的酶学性质是：最适pH为9．0,在pH5．0—10．0于20℃下放置24h后,残余酶活仍保持在起始酶活的90％以上;该酶的最适温度为50℃,50℃保温60min后仍保留70％以上的酶活。Aspergillus sp．所产脂肪酶的热稳定性较好。     

红树林微生物DH-2胞外蛋白酶的性质及产酶条件优化

从大亚湾红树林土壤样品中分离得到产蛋白酶菌株,鉴定所产胞外蛋白酶的酶学性质以及菌株的最佳发酵培养条件。采用平板透明圈法筛选菌株,福林酚显色法测定蛋白酶的酶活,通过单因素和正交试验确定其最佳发酵培养基以及发酵条件。从壤样品中分离得到一株产蛋白酶的枯草芽孢杆菌DH-2,该菌株分泌的蛋白酶最适反应pH和温度分别为8.0和65℃,50℃保温处理60 min后,剩余酶活仍保留80%以上。该蛋白酶对多种金属离子、有机溶剂及表面活性剂均有较好的耐受性。确定该菌株产蛋白酶的最适条件:1%(m/V,下同)可溶性淀粉,1%胰蛋白胨、1%NaCl,初始pH 5.5及7%的接种量,40℃培养36 h。在最适条件下测得其发酵液的酶活为236.30 U/mL,约为初筛时的酶活的8倍。该蛋白酶具有较为广阔的作用温度和pH范围,金属离子、有机溶剂及表面活性剂耐受性好,酶的性质比较稳定。     

白腐真菌AH28-2菌株发酵合成漆酶初步研究*

从 2 2 4个野外采集的真菌样品中筛选分离到一株产漆酶活性较高菌株AH28-2 ,经初步鉴定为白腐真菌。采用单因子相互比较法 ,研究了该菌株最适发酵产酶条件。应用添加有 1g/Lkraft木素的液体发酵培养基 ,接种量 5 %(V/V) ,初始pH8 5 ,装液量为 5 0 %,2 8℃、 1 5 0r/min摇瓶振荡培养 4～ 5d ,漆酶酶活水平达 2 0 1 84IU/L。     

产壳聚糖酶菌株的发酵条件优化

方法:通过单因子实验,对保存的1株产壳聚糖酶的菌株C001进行发酵产酶条件优化,确定了最适产酶培养基组分.结果:温度30℃,发酵时间18h,pH5.5,接种量5%优化发酵条件后,产壳聚糖酶活力增长了37.4%.     

哈茨木霉T-23产几丁质酶发酵条件的研究

拟通过研究哈茨木霉T-23的产几丁质酶的最适发酵条件,并从中找出合理的发酵条件用于几丁质酶的工业化生产。通过在不同发酵条件下单因素实验培养T-23,分别测定不同培养液中的几丁质酶活性。综合各个试验结果,T-23以2％胶体几丁质为碳源,2％蛋白胨为氮源,在250mL三角瓶中50mL装瓶量,6％接种量,初始pH为5,25℃,180r／min,培养4d时,可使发酵液中的几丁质酶活达到最高。     

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.