谷氨酸棒状杆菌发酵生产L-瓜氨酸及发酵条件优化

以代谢控制发酵理论为指导,重点对C.glutamicum 366菌株进行摇瓶发酵条件的优化。应用响应面法优化发酵培养基的配比,优化后的发酵培养基:葡萄糖63.33 g/L、精氨酸196.96 mg/L、(NH4)2SO445.79 g/L、生物素35.72μg/L、K2HPO4·3H2O 1.0 g/L、KH2PO41.0 g/L、Mg SO4·7H2O、0.25 g/L、Mn SO4·H2O 0.02 g/L、Fe SO4·7H2O 0.02g/L、Zn Cl21 mg/L、Cu SO40.2 mg/L、VB1200μg/L、Ca CO330 g/L。摇瓶发酵培养条件:温度30℃、摇床转速200r/min、初始p H 7.0。在此发酵条件下,菌株进行摇瓶发酵72 h,产L-瓜氨酸14.96 g/L,相比优化之前提高了75.8%。     

发酵生产S-腺苷-L-蛋氨酸培养条件的优化研究

考察了摇瓶发酵生产S-腺苷-L-蛋氨酸过程中碳源、氮源、无机盐和生长因子以及培养过程中补加L-蛋氨酸时间对S-腺苷-L-蛋氨酸的产量、含量及生物量的影响。并通过均匀实验设计对培养基配方进行优化,在30℃、180 r/m in的培养条件下,得到最后的培养基配方为:葡萄糖30g,酵母粉11g,(NH4)2SO412g,K2HPO4.3H2O 5g,KH2PO410g,MnSO4.H2O 0.09g,ZnSO4.7H2O 0.14g,MgC l20.5g,CaC l20.3g,CuSO40.005g,自来水定容至1L。摇瓶中优化后的S-腺苷-L-蛋氨酸产量可以达到0.9g/L,比优化前产量提高了30%。采用优化后的培养基和培养条件在5L发酵罐中间歇培养,24h后一次性补加24g/L葡萄糖和1.0g/L L-蛋氨酸,继续培养24h后产量可达2.66g/L,生物量23.4g/L。     

响应面法优化短短芽胞杆菌ch2-22的发酵工艺

在摇瓶发酵条件下,优化提高短短芽胞杆菌ch2-22芽胞浓度和抑菌活性的发酵培养基和培养条件。首先在单因素试验基础上进行响应面设计对ch2-22的发酵培养基进行优化,然后使用单因素试验方法确定最佳发酵条件,得到优化发酵培养基为淀粉35.05 g/L,豆饼粉26.08 g/L,蔗糖10 g/L,鱼粉5 g/L,Na Cl 1 g/L,Mg SO40.3 g/L,(NH4)2SO43 g/L,Mn SO40.1 g/L,K2HPO43 g/L,酵母膏1 g/L,Ca CO32 g/L。培养条件为温度32℃,转速180 r/min,装液量100 m L/500 m L,接种量4%,初始pH为7.0,发酵时间45 h。优化后的芽胞数量达到8.1×109cfu/m L,与优化前的芽胞数量(1.6×109cfu/m L)相比,提高了3.7倍,优化后发酵液效价达到3 350 IU/m L,提高了109%,高于同类菌株的2 000 IU/m L。     

L-缬氨酸发酵条件的研究

报道了L 缬氨酸高产菌XQ 6(Leu1AHVrα ABhr2 TAhr)摇瓶发酵条件的研究结果。试验结果表明 ,当发酵培养基中葡萄糖、(NH4 ) 2 SO4 、KH2 PO4 、MgSO4 ·H2 O、玉米浆和生物素的最适用量分别为 1 4 %、5 %、0 .1 %、0 .0 5 %、0 .5 %和2 5 μg/L时 ,经发酵培养 72h ,L 缬氨酸积累可达 5 8g/L ,最高为 62g/L。     

高山被孢霉产花生四烯酸发酵条件的研究

通过一株高山被孢霉M_(20)(Mortierella alpina)产花生四烯酸的摇瓶发酵研究,确定了其最佳发酵培养基组成及最适摇瓶发酵工艺条件。摇瓶实验确定的最佳培养基组成为(g/L):玉米粉水解液葡萄糖150,酵母粉15,KH_2PO_4 3.0,NaNO_3 3.0,MgSO_4·7H_2O 0.5。最佳发酵工艺条件为:初始pH6.5,装液量为50ml/500ml摇瓶,摇床转速150r/min,温度在菌体生长前三天控制在25℃培养,以后调至20℃培养。在此条件下,发酵培养被孢霉的生物量、菌体总油脂及花生四烯酸分别高达35.5g/L、13.2g/L及2.2g/L,在15L及1000L自动机械搅拌罐进行发酵试验,AA产量分别高达1.86g/L及1.70g/L。     

氮源对重组大肠杆菌发酵产L-精氨酸的影响

考察有机氮源种类、蛋白胨用量以及(NH4)2SO4用量对重组E.coli发酵产L-精氨酸的影响.结果表明:以蛋白胨作为有机氮源且用量在10 g/L,( NH4 )2SO4用量在15 g/L时,摇瓶发酵产L-精氨酸产量最高,达到9.4g/L.在5L发酵罐进行补料分批培养,通过补加(NH4)2 SO4,L-精氨酸产量可以达到18.8 g/L,比未补加提高了108.9％.     

麦芽糖诱导软化芽孢杆菌α-环糊精葡萄糖基转移酶在枯草杆菌中的表达

通过PCR扩增软化芽孢杆菌α-环糊精葡萄糖基转移酶基因,将基因片段克隆到大肠杆菌-枯草杆菌穿梭载体pGJ103中,转化枯草杆菌WB600得基因工程菌进行外源表达。在1.5%的麦芽糖初始发酵培养基上摇瓶培养,48 h后重组枯草杆菌产酶活性为6.1U/ml。通过单因素分析和响应面分析对重组枯草杆菌产CGT酶摇瓶发酵条件进行优化。分析得到培养基关键组分麦芽糖,玉米淀粉和酵母粉三者最佳浓度分别为:15.5g/L,13g/L和20g/L。在此条件下,摇瓶培养36h后α-CGT酶活性为17.6U/ml,5L罐分批发酵30h后酶活达到20U/ml (水解活性为1.4×10⁴ IU/ml)。     

高产类胡萝卜素酵母菌株LRY-01发酵条件的优化研究

通过单因子实验研究了不同碳源、氮源、生长因子及通气量对菌株LRY-01生产类胡萝卜素的影响。实验表明,碳源、氮源、生长因子对类胡萝卜素产量的影响较大。进一步对上述因子进行了L9(34)正交实验,得到了最佳培养基配方及发酵条件:葡萄糖40g/L,(NH4)2SO41.0g/L,核黄素0.5mL/L,酵母膏0.5g/L,初始pH 4.5,摇瓶装液量为10%。菌株LRY-01在此条件下摇瓶培养72h的生物量和类胡萝卜素的产量分别可达16.19g/L和1000.06μg/g。     

L-谷氨酰胺高产菌的选育和发酵条件

以嗜乙酰乙酸棒杆菌(Corynebacterium acetoacidophilum)LG-3为出发菌株,经紫外线(UV)和硫酸二乙酯(DES)诱变处理,磺胺胍(SG)、高浓度(NH4)2SO4定向筛选,获得1株谷氨酰胺高产菌株LG-65,在未经优化的条件下摇瓶发酵72 h可产谷氨酰胺43.5 g/L,比出发菌株的产量32.4 g/L提高了34.3%.在此基础上,对其发酵条件进行优化,经72 h摇瓶发酵产量可达47～48 g/L,7 L发酵罐补料分批发酵40 h可达55 g/L.     

一株苝产醌类光敏剂丝状真菌AL18的液体发酵工艺研究

为研究一株丝状真菌AL18产苝醌类光敏剂的液体发酵工艺.以马铃薯综合培养基为发酵培养基,采用单次单因素实验法,研究了液体摇瓶培养条件对苝醌类光敏剂产量的影响.实验结果表明液体摇瓶最适培养条件为250ml三角瓶装液量40ml,接种量7.5%,接种种龄40h,初始pH5.75,摇床转数180r/min,30℃振荡培养48h.在此培养条件下,采用单因素法筛选了发酵培养基中的碳源、氮源和无机离子,选用L9(34)对筛选到的绵白糖(A)、蛋白胨(B)、蚕蛹粉(C)、CuSO4·5H2O(D)进行了正交试验.经优化后的发酵培养基配方为马铃薯200g/L,绵白糖30g/L,蛋白胨3g/L,蚕蛹粉12.5g/L,磷酸二氢钾1g/L,硫酸镁0.5g/L,硫酸铜0.05g/L,VB1 100mg/L.对此发酵培养基配方进行了5次验证实验,苝醌类光敏剂的平均产量为1.21g/L.     

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).     

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.