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1.
以thyA基因为选择压力非抗性质粒载体的构建   总被引:8,自引:0,他引:8  
以干酷乳杆菌L.casei34103染色体DNA为模板,利用PCR技术扩增胸苷酸合成酶(Thymidylatesynthase,thyA)基因,回收纯化,选择以红霉素抗性为选择压力的可以在大肠杆菌和乳酸菌中穿梭表达的质粒pW425e为基本质粒,以thyA基因取代红霉素基因,获得重组载体并鉴定,此重组载体可以对thyA基因缺陷的大肠杆菌E.coli X51和嗜酸乳杆菌DOMLaS 107进行功能弥补,进而构建了以thyA基因为地选择压力的非抗生素抗性穿梭表达载体,其大小为3716bp,并命名为pW425t。  相似文献   

2.
作为宿主系统的几株乳酸菌的表型特征   总被引:4,自引:0,他引:4  
目的:研究乳酸菌载体-宿主系统。方法:采用涂片染色和形态特征观察,用鉴别生化实验如过氧化氢酶实验,碳水化合物发酵产酸实验,精氨酸水解实验及抗生素抗性实验等对含有pMG36e质粒的乳酸菌MG1363,乳球菌IL1403和乳杆菌ATCC4356进行研究鉴定。结果:乳酸乳球菌乳脂亚种MG1363,乳酸乳球菌乳酸亚种IL1403含有质粒pMG36e的MG1363致及嗜酸乳杆菌ATCC4356其表型特征分别与伯杰氏手册中相应细菌特征一致,质粒pMG36e含有红霉素抗性基因,结论:此乳酸菌宿主一载体系统可用载体来源的红霉素抗性进行筛选,用于外源基因在乳酸菌中克隆和表达的研究。  相似文献   

3.
以猪A组轮状病毒mRNA为模板,应用反转录聚合酶链式反应(RT-PCR)技术,扩增了1194bp的Vp6基因,通过T-A克隆技术,将PCR产物克隆至克隆载体pGEM-TVector中,构建克隆质粒pGEM-T-Vp6。用SacⅠ和KpnⅠ双酶切pGEM-T-Vp6和以胸苷酸合成酶基因(thymidylate synthase,thyA)为选择压力的非抗生素抗性的穿梭表达载体pW425t,并将纯化的Vp6基因亚克隆至表达载体pW425t中,构建出可以在乳酸菌与大肠杆菌之间穿梭表达的原核表达重组质粒pW425t-Vp6。将pW425t-Vp6转化至thyA基因缺陷型的大肠杆菌感受态E.coliX13中,经生长功能弥补筛选阳性克隆,通过SDS-PAGE分析,可见约44.88kD的融合蛋白。由Western blot分析,表明该蛋白具有与轮状病毒多克隆抗体的反应原性,从而为pW425t-Vp6在乳酸菌受体菌株中表达提供理论基础和实验依据。  相似文献   

4.
乳酸菌食品级nisin控制的基因表达系统NICE   总被引:3,自引:0,他引:3  
乳酸菌安全应用于人们的生产和生活已有上千年的历史,是一种食品级的微生物。在过去二十年里,其生理及遗传学特性已被彻底研究。由于其遗传可行且操作简单,乳酸菌除了其传统应用外已被广泛用于表达异源基因,在食品、农业及医药工程领域具有重要的应用前景。人们已开发了一系列乳酸菌食品级基因表达系统。本文主要介绍了乳酸菌,重点是其模式菌Lactococcus lactis最常见的食品级诱导表达系统--nisin控制的基因表达系统NIC E及其食品级诱导物nisin、食品级的宿主及表达载体系统,以及NICE系统在表达异源基因方面的应用。  相似文献   

5.
[目的]构建并筛选重组gRNA(向导RNA)表达质粒p SJCR-LDH和p SJCR-C9PX,并对gRNA在乳酸菌中的表达进行鉴定。[方法]通过PCR技术扩增复制子SH71、氯霉素抗性基因CM和gRNA表达盒片段。将CM片段分别与gRNA表达盒进行融合,再与SH71复制子进行无缝克隆。通过转化,构建重组质粒p SJCR-LDH和p SJCR-C9PX。应用PCR、RT-PCR、Real-Time PCR对重组质粒进行鉴定,gRNA表达验证及拷贝数检测。[结果]PCR及RT-PCR结果显示获得169 bp大小目的条带,表明获得重组质粒载体且该gRNA表达载体在植物乳杆菌WCFS1株、CGMCC1.557株、乳酸乳球菌MG1363株中均成功表达,绝对荧光定量PCR检测获得LDH-gRNA标准曲线为y=-3.480log X+45.34,扩增效率为93.8%;C9PX-gRNA标准曲线为y=-3.327log X+37.07,扩增效率为99.8%。[结论]为利用CRISPR基因编辑技术在乳酸菌中进行基因操作奠定基础,为乳酸菌载体构建提供方法。  相似文献   

6.
目的克隆猪白细胞介素18(pIL-18)成熟蛋白基因,并在植物乳杆菌(Lb.plantarum)NC8中进行表达。方法通过RT-PCR方法从猪脾脏细胞中扩增出pIL-18成熟蛋白基因,克隆到T载体pMD18-T后测序;将阳性基因片段克隆至大肠埃希菌-乳酸菌穿梭表达载体pSIP-409构建重组表达载体pSIP-409-IL-18,进行酶切和PCR鉴定;应用电穿孔技术将其转化至Lb.plantarum NC8中,经SppIP诱导表达后,进行SDS-PAGE及Western-blot分析。结果经测序,pIL-18成熟蛋白基因核苷酸长度为579 bp,编码193个核苷酸;酶切和PCR鉴定证明成功构建了重组表达载体pSIP-409-IL-18;SDS-PAGE及Western-blot分析表明重组菌表达了18 kD的融合蛋白,该重组蛋白可以与鼠抗猪IL-18多克隆抗体反应。结论成功克隆了pIL-18成熟蛋白基因,并获得有生物活性的pIL-18重组乳酸菌,为研制开发IL-18重组乳酸菌制剂奠定基础。  相似文献   

7.
[目的]构建并筛选重组gRNA(向导RNA)表达质粒p SJCR-LDH和p SJCR-C9PX,并对gRNA在乳酸菌中的表达进行鉴定。[方法]通过PCR技术扩增复制子SH71、氯霉素抗性基因CM和gRNA表达盒片段。将CM片段分别与gRNA表达盒进行融合,再与SH71复制子进行无缝克隆。通过转化,构建重组质粒p SJCR-LDH和p SJCR-C9PX。应用PCR、RT-PCR、Real-Time PCR对重组质粒进行鉴定,gRNA表达验证及拷贝数检测。[结果]PCR及RT-PCR结果显示获得169 bp大小目的条带,表明获得重组质粒载体且该gRNA表达载体在植物乳杆菌WCFS1株、CGMCC1.557株、乳酸乳球菌MG1363株中均成功表达,绝对荧光定量PCR检测获得LDH-gRNA标准曲线为y=-3.480log X+45.34,扩增效率为93.8%;C9PX-gRNA标准曲线为y=-3.327log X+37.07,扩增效率为99.8%。[结论]为利用CRISPR基因编辑技术在乳酸菌中进行基因操作奠定基础,为乳酸菌载体构建提供方法。  相似文献   

8.
构建抗菌肽Bactenecin7分泌表达载体,鉴定表达产物及检测其生物活性。采用重叠延伸PCR方法拼接合成Bactenecin7基因及其相关调控元件,将目的基因克隆到穿梭载体 pMG36e中,经鉴定后电击转化乳酸菌。通过RT PCR,Western blot检测目的基因表达情况,采用琼脂扩散法对表达产物的生物活性进行初步检测。结果显示成功构建了携Bactenecin7基因的重组质粒,将重组质粒转化至乳酸菌后,该乳酸菌能有效分泌表达Bactenecin7,经体外抑菌实验证实表达产物Bactenecin7具有抑菌活性。实验表明携Bactenecin7基因的乳酸菌能有效分泌表达具有生物活性的抗菌肽Bactenecin7,为进一步研究口服重组乳酸菌进行肠道细菌感染的治疗奠定了基础。  相似文献   

9.
克隆了大肠杆菌和霍乱弧菌胸腺嘧啶合成酶基因thyA ,并以pcDNA3质粒为基础 ,分别用两种来源的thyA基因替代其氨苄抗性基因Amp,构建了不含抗性基因 ,且可在thyA营养缺陷型大肠杆菌中基于染色体 质粒平衡致死系统稳定传代的真核表达载体。该载体可有效表达红色荧光蛋白报告基因。为核酸疫苗的制备提供一个无抗性的表达载体系统  相似文献   

10.
本文报道了链霉菌和大肠杆菌穿梭质粒载体pSE-3的构建;把具有双启动子的大肠杆菌的质粒pGEM-3与新霉素抗性基因启动子缺失的链霉菌的探针质粒pIJ486分别用BamHI和BglⅡ酶切,T4 DNA连接酶连接后转化到E.coli HB101(Amp(?),Neo(?)),所得重组质粒能强启动pIJ486质粒上的氨基糖苷磷酸转移酶基因(aph),并使新霉素抗性基因在大肠杆菌中得到强表达。此重组质粒被命名为pSE-3,当其转化到变青链霉菌TK54(Tsr(?),Neo(?))的原生质体前,新霉素抗性基因亦能得到强表达。酶切结果表明,构建的具有两个启动子的穿梭质粒载体pSE-3上有HindⅢ和EcoRI的单酶位点,拷贝数约为39。经再转化和传代50代等研究表明,穿梭质粒载体pSE-3在链霉菌和大肠杆菌中均是稳定的。为某些有应用价值的目的基因在大肠杆菌和链霉菌中的克隆与表达提供了一个有价值的穿梭质粒载体。  相似文献   

11.
Lactic acid bacteria (LAB) have a long history of use in fermented foods and as probiotics. Genetic manipulation of these microorganisms has great potential for new applications in food safety, as well as in the development of improved food products and in health. While genetic engineering of LAB could have a major positive impact on the food and pharmaceutical industries, progress could be prevented by legal issues related to the controversy surrounding this technology. The safe use of genetically modified LAB requires the development of food-grade cloning systems containing only the DNA from homologous hosts or generally considered as safe organisms, and not dependent antibiotic markers. The rationale for the development of cloning vectors derived from cryptic LAB plasmids is the need for new genetic engineering tools, therefore a vision from cryptic plasmids to applications in food-grade vectors for LAB plasmids is shown in this review. Replicative and integrative vectors for the construction of food-grade vectors, and the relationship between resistance mechanism and expression systems, will be treated in depth in this paper. Finally, we will discuss the limited use of these vectors, and the problems arising from their use.  相似文献   

12.
食品级乳酸菌表达系统研究进展   总被引:2,自引:0,他引:2  
乳酸菌表达系统是近几年发展起来的食品级高效表达系统。乳酸菌具有益生菌特征,因此该表达系统与其他细菌表达系统相比有很多优点。介绍了糖诱导表达系统、噬菌体Φ31爆发式诱导的表达系统、乳链球菌素调控表达系统、温控表达系统等的研究进展,以及这些系统的应用前景。  相似文献   

13.
应用于乳酸菌的非抗生素抗性选择标记系统   总被引:3,自引:0,他引:3  
 乳酸菌是一类重要的安全型微生物,在免疫载体疫苗开发及食品菌株改良等医疗、食品领域均有广泛的应用.非抗生素抗性选择标记是乳酸菌基因工程菌株构建中必不可少的关键组成部分,也是目前乳酸菌研究的前沿和热点.根据筛选时质粒和受体菌之间的表型关系及特征,主要分为显性选择标记、互补型选择标记、显性/互补型选择标记、双质粒选择标记4大类.其中显性选择标记中的细菌素抗性/免疫性选择标记及互补型选择标记中的糖类选择标记均有较大的发展潜力及应用空间;双质粒选择标记系统构建的筛选过程新颖独特,为整个选择标记系统的发展开辟了新的途径及思路.  相似文献   

14.
Acquired antibiotic resistance in lactic acid bacteria from food   总被引:17,自引:0,他引:17  
Acquired antibiotic resistance, i.e. resistance genes located on conjugative or mobilizable plasmids and transposons can be found in species living in habitats (e.g. human and animal intestines) which are regularly challenged with antibiotics. Most data are available for enterococci and enteric lactobacilli. Raw material from animals (milk and meat) which are inadvertantly contaminated with fecal matters during production will carry antibiotic resistant lactic acid bacteria into the final fermented products such as raw milk cheeses and raw sausages. The discovered conjugative genetic elements of LAB isolated from animals and food are very similar to elements studied previously in pathogenic streptococci and enterococci, e.g. -type replicating plasmids of the pAM1, pIP501-family, and transposons of the Tn916-type. Observed resistance genes include known genes like tetM, ermAM, cat, sat and vanA. A composite 29'871 bp resistance plasmid detected in Lactococcus lacti s subsp. lactis isolated from a raw milk soft cheese contains tetS previously described in Listeria monocytogenes, cat and str from Staphylococcus aureus. Three out of five IS elements on the plasmid are almost or completely identical to IS1216 present in the vanA resistance transposon Tn1546. These data support the view that in antibiotic challenged habitats lactic acid bacteria like other bacteria participate in the communication systems which transfer resistance traits over species and genus borders. The prevalence of such bacteria with acquired resistances like enterococci is high in animals (and humans) which are regularly treated with antibiotics. The transfer of antibiotic resistant bacteria from animals into fermented and other food can be avoided if the raw substrate milk or meat is pasteurized or heat treated. Antibiotic resistance traits as selectable markers in genetic modification of lactic acid bacteria for different purposes are presently being replaced, e.g. by metabo lic traits to generate food-grade vectors.  相似文献   

15.
乳酸菌的安全性研究   总被引:1,自引:0,他引:1  
乳酸菌通常被认为是安全的,但在机体免疫抑制、肠道发育未成熟、肠上皮受损等情况下,可以导致心内膜炎、菌血症、局部性感染等临床症状.本文综述了国外有关乳酸菌的致病性、抗药性基因转移方面研究的一些新进展,以期引起国内对乳酸菌安全性问题的重视.  相似文献   

16.
曾珠 《生物工程学报》2021,37(7):2272-2282
乳酸菌是被公认为安全的食品级微生物,广泛地应用于食品生产、保存以及作为益生菌促进人类健康.鉴于发展有效的投递药物分子策略的需要,乳酸菌成为了极有吸引力的用于口服、鼻饲及阴道进行粘膜投递药物分子的活载体.用乳酸菌作为药物分子的投递载体,安全性好,且可直接合成并投递目标蛋白,显著降低药物生产成本.到目前为止,乳酸菌作为粘膜...  相似文献   

17.
食源性致病菌严重威胁人类的生命健康。服用抗生素是目前最有效的治疗手段。但不规范使用抗生素,导致耐药性细菌日趋普遍。乳酸菌是公认的食品级安全微生物,因其具有拮抗致病菌、增强免疫功能、加强肠道屏障、平衡肠道菌群等功能而具有良好的应用前景,有望成为下一代安全、稳定、经济的生物抗菌剂,以减少甚至替代抗生素的使用。本文通过阐述乳酸菌抗菌物质、抗菌机制及抗菌功能特性等,以促进乳酸菌的研究和应用。  相似文献   

18.
Engineering metabolic highways in Lactococci and other lactic acid bacteria   总被引:13,自引:0,他引:13  
Lactic acid bacteria (LAB) are widely used in industrial food fermentations and are receiving increased attention for use as cell factories for the production of food and pharmaceutical products. Glycolytic conversion of sugars into lactic acid is the main metabolic highway in these Gram-positive bacteria and Lactococcus lactis has become the model organism because of its small genome, genetic accessibility and simple metabolism. Here we discuss the metabolic engineering of L. lactis and the value of metabolic models compared with other LAB, with a particular focus on the food-grade production of metabolites involved in flavour, texture and health.  相似文献   

19.
Progress and potential in the biotechnology of lactic acid bacteria   总被引:2,自引:0,他引:2  
Abstract: Current activities and future prospects for the biotechnology of lactic acid bacteria are reviewed. Genetic engineering technology, including advances and limitations of plasmid vectors and chromosomal integration strategies are discussed together with the status of gene expression and the importance of in vivo gene transfer systems and transposition. Areas of biotechnological application considered include proteolysis and flavour generation, bacteriophage resistance, antimicrobials, metabolic engineering and the possible uses of lactic acid bacteria in relation to health.  相似文献   

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