酪酸梭菌与双歧杆菌对肠道致病菌的体外生物拮抗作用

目的：探讨酪酸梭菌和婴儿型双歧杆菌对某些肠道致病菌的拮抗作用,方法：将酪酸梭菌和婴和型双歧杆菌单株菌及两株菌混合后分别与几株肠道致病菌混合接种于GAM液体培养其中进行厌氧培养,通过平板菌落计数法计算肠道致病菌的菌数,结果：经混合培养后肠道致病菌的菌数明显下降,结论：酪酸梭菌LCL166株和婴儿型双歧杆菌LCL172株在体外能明显抑制几株肠道致病菌的生长繁殖。     

水貂粪便中双歧杆菌的分离与鉴定

目的运用TPY培养基,从健康水貂的粪便中分离培养、筛选出2个肠道菌株。方法细菌培养、菌落形态观察、染色镜检、分离纯化、生化试验和药敏试验。结果分离培养出的2株菌株为双歧杆菌,其中1株为长双歧杆菌,另1株为青春双歧杆菌;双歧杆菌对氯霉素极其敏感,对阿米卡星耐药。结论本实验为毛皮特种经济动物微生态制剂的研究工作奠定了基础。     

一株抑制单增李斯特菌感染的S.epidermidis G26菌株的分离筛选

本研究从BALB/c小鼠粪便中分离筛选得到一株具有抑制单增李斯特菌(Listeria monocytogenes,Lm)感染的G26菌株。通过16S rDNA鉴定分离株G26为表皮葡萄球菌(Staphylococcus epidermidis G26)。体外试验证明G26能够显著抑制Lm生长;动物实验表明,分离株G26能够降低单增李斯特菌感染小鼠的死亡率,减少单增李斯特菌在小鼠肠道内的含量和粪便检出量。结果表明,分离株G26可以作为一种具有治疗单增李斯特菌感染作用的潜在的益生菌。     

筛选鸡嗉囊降解胆固醇的内源益生菌

目的:益生菌具有降低胆固醇作用,从鸡嗉囊内利用选择性培养基筛选和复选具有降低胆固醇作用的内源益生菌.方法:利用MRS培养基和以胆固醇为碳源的复选培养基分别进行好氧、兼性、厌氧培养,逐层倒平板划线分离,最终分离和筛选出纯的益生菌,观察描述其菌落形态特征和油镜下观察菌株的特征,并进行一系列生化实验,结合伯杰氏细菌鉴定手册初步确定益生菌种类.结果:筛选分离出1株好氧菌、1株兼性菌、1株厌氧菌,分别命名为DG-1、DG-2、DG-3;初步鉴定为乳酸菌属、乳杆菌属、消化链球菌属.结论:该试验方法简单易行,能够有效地从鸡嗉囊中筛选出生长良好的益生菌,为进一步研究内源益生菌降解胆固醇的特性及机理提供帮助.     

酪酸梭状芽胞杆菌研究进展

酪酸梭状芽胞杆菌（Clostridium butyricum）是属于硬壁菌门（Firmicutes）梭菌纲（Clostridia）梭菌目（Clostridiales）梭菌科（Clostridiaceae）梭菌属（Clostridium）的一种革兰阳性菌（以下简称酪酸梭菌）。早在1877年就开始了对酪酸梭菌的研究。近130年以来,不同国别的不同研究者曾经先后用了10来种不同的名称记录或描述这个菌种（表1）,1980年学术界规范地将其统一命名。尽管早已有文献报道酪酸梭菌是人的正常肠道菌,但是在i999年2月由联合国粮农组织（FAO）和世界卫生组织（WHO）联合在罗马召开的第52次食品添加剂专家委员会的会议文件中还是再次指出了酪酸梭菌是人的正常肠道菌这一事实。酪酸梭菌是严格的厌氧菌,产生丁酸,所以也有人将其称为丁酸梭菌。它们不仅存在于人的肠道中,也存在于动物肠道和土壤中。在一定条件下形成孢子。     

一株产γ-氨基丁酸的戊糖片球菌分离鉴定及药敏分析

目的 从健康人肠道微生物群中分离功能菌株。方法 从健康人粪便中分离肠道菌株,进行形态学观察、生理生化鉴定和16S rDNA测序分析,并对分离的菌株进行耐药特性评估,利用ELISA试剂盒测定发酵液中γ-氨基丁酸的含量。结果 本研究分离得到菌株为革兰阳性球菌,生理生化反应初步判断为片球菌属,16S rDNA测序鉴定为戊糖片球菌（Pediococcus pentosaceus）,该菌株命名为P. pentosaceus WMU002。该菌株对氨苄西林、亚胺培南、头孢曲松、头孢噻肟、大环内酯类红霉素、克林霉素和哌拉西林敏感,对丁胺卡那、新生霉素、头孢西丁和甲氧嘧啶耐药。24 h发酵液γ-氨基丁酸含量为4.12μmol/L。结论 从健康人肠道中分离获得的1株产γ-氨基丁酸的P. pentosaceus WMU002菌株可作为人体益生菌制剂候选菌株。     

不同饲喂下棉铃虫肠道内生菌的分离鉴定及脱毒效果研究

【目的】本研究对比饲喂正常饲料和棉粕饲料下棉铃虫(Helicoverpa armigera)肠道中可培养微生物的异同,并对筛选菌株进行棉酚耐受及降解作用的研究,为棉铃虫肠道微生物在棉源饲料中的脱毒作用提供理论和实验支持。【方法】通过饲喂不同饲料、醋酸棉酚单一碳源微生物选择性培养,分离饲喂正常饲料和棉粕饲料下棉铃虫肠道可培养棉酚耐受性内生菌,并进行16S rRNA基因序列分析鉴定;在一定浓度的醋酸棉酚液体中培养,对菌株进行脱毒作用分析,复合配比后,研究棉铃虫肠道复合菌在棉酚降解中的效果。【结果】共计分离得到的32株菌株,其中17株细菌可能是新分类单元,其中14株为潜在新种,3株为可能的新属。饲喂正常饲料组棉铃虫肠道中分离出17株分属于3个门、10个属,饲喂棉粕饲料组棉酚虫肠道中分离出15株属于2个门、8个属。随着选择性培养基醋酸棉酚浓度的升高,饲喂棉粕饲料组肠道菌耐受100、300、500、1 000 mg/kg醋酸棉酚的菌株数均比饲喂正常饲料组高。在所有的耐受菌株中棉酚降解率达到50%以上的有15株,对棉酚最高降解率达90.83%。在肠道菌复合降解棉酚实验中,棉铃虫肠道内生菌实验组对棉...     

酪酸梭菌和婴儿型双歧杆菌对霍乱弧菌的拮抗试验

了解酪酸梭菌和婴儿型双歧杆菌单独及混合培养时对霍乱弧菌的拮抗作用。将酪酸梭菌ＬＣＬ１６６和婴儿型双歧杆菌ＬＣＬ１７２分别与霍乱弧菌Ｏ１、Ｏ１３９单独和混合培养,定时对霍乱弧菌计数,并对菌数的对数进行在检验。两株菌混合培养时对霍乱弧菌的抑制效果基本相同,单独和混合培养时对霍乱弧菌的拮抗作用主要由酪酸梭菌引起,酪酸梭菌具有抑制霍乱弧菌的作用。     

斑节对虾(非洲群体)肠道中哈维氏弧菌拮抗菌的筛选、鉴定及生理特性分析

基于斑节对虾(非洲群体)(Penaeus monodon)肠道菌的生理生化特性, 为解决斑节对虾急性肝胰腺坏死综合征(AHPND)提供新思路, 文章分离纯化健康斑节对虾肠道中的优势菌株; 以致病性哈维氏弧菌为指示菌, 用牛津杯法从纯化菌株中筛选拮抗菌; 通过生理生化特征、Biolog系统鉴定及16S rDNA技术综合方法对菌株进行鉴定; 通过药敏实验, 评价拮抗菌株的安全性; 绘制高敏拮抗菌株的生长曲线, 得出其生长特性; 通过测定其产酶活性, 形成对其益生机制的初步推断。从斑节对虾肠道中共分离得到14株的优势土著菌, 分别标记为P.m-1、P.m-2······P.m-14, 经过拮抗实验得到了3株拮抗菌(P.m-1、P.m-9和P.m-13)。经鉴定P.m-1、P.m-9和P.m-13分别为枯草芽孢杆菌(Bacillus subtilis)、屎肠球菌(Enterococcus faecium)和溶藻弧菌(Vibrio alginolyticus)。药敏实验结果表明, 3株拮抗菌均不属于耐药菌, P.m-1对药物高度敏感。生长特征实验表明: P.m-1在2h进入对数期, 10h达到生长高峰, 菌体密度可达1.14×109 cfu/mL, 表现出了强劲的生命力。经过蛋白酶活性测定, P.m-1具有较强的产酶能力。优势菌P.m-1具有成为益生菌的潜力, 后续将作为功能性饲料添加剂或水质调节剂进行应用, 为AHPND进行生物防治提供新思路。     

24株鸡源丁酸梭菌的分离鉴定及耐药基因与毒力基因携带情况

【目的】旨在对鸡源丁酸梭菌进行分离鉴定与安全性评估。【方法】利用厌氧培养方法对源自汶上芦花鸡与SPF鸡粪便样品进行丁酸梭菌的分离与纯化,挑选可疑菌落进行微生物质谱鉴定,进一步通过16S rRNA基因测序进行鉴定,16S rRNA测序结果与NCBI核苷酸数据库中丁酸梭菌的16S rRNA序列进行同源性分析;同时,进行所有分离株对氧氟沙星、头孢吡肟等9种药物的药敏试验,利用PCR方法进行mefA等23种耐药基因扩增,基于益生菌安全要求对样品进行alpha等4种梭菌毒素基因以及typeA等4种肉毒毒素基因的测定。【结果】共分离鉴定了24株丁酸梭菌。24株均对氧氟沙星等7种抗生素表现为敏感,L-1、L-6、L-12仅对新霉素表现为中介,L-19仅对头孢吡肟表现为中介。全部菌株的mefA等16种耐药基因结果全部为阴性,sul2、flor、blaTEM 3种耐药基因全部呈阳性,tetC携带率为79.2%,cmlA携带率为45.8%,blaOXA携带率为37.5%,aadB携带率为12.5%,qnrA携带率为4.2%。PCR结果显示所有分离菌株的alpha、beta、epsilon、iota等4种梭菌毒素基因携带率0%。全部分离菌株均未携带typeA、typeB、typeE、typeF 4种肉毒毒素基因。【结论】结果表明,从未饲喂抗生素和丁酸梭菌的汶上芦花鸡与SPF鸡群中获得的24株丁酸梭菌分离株达到预期的安全性要求,可作为益生添加菌的筛选参考株。     

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.