乳酸菌食品级筛选标记研究进展

构建食品级载体是开发乳酸菌潜在应用价值的关键。筛选标记是载体的重要组成部分,也是目前乳酸菌遗传学研究领域的一个热点。本文对国内外已构建的食品级筛选标记系统,包括抗性筛选标记系统、互补型筛选标记系统进行了综述,以期对食品级筛选标记系统的进一步研究提供有价值的参考。     

基于pyrF的乳酸乳球菌食品级表达载体的构建

基于pyrF筛选标记和来源于乳酸乳球菌(Lactococcus lactis,L. lactis)的基因组DNA为表达元件,构建L. lactis食品级表达载体,用于食品和药用多肽的表达和生产。首先,利用NZ3900 pyrF基因列构建同源重组突变盒,构建NZ3900ΔpyrF突变株;然后,分别以来源于L. lactis的repA和repC基因为复制元件、pyrF基因为筛选标记、P₃₂和P₈为启动子、以及Tusp₄₅和TpepN为终止子,构建食品级表达质粒pLD;最后以绿色荧光蛋白ZsGreen为报告基因,验证ZsGreen在NZ3900ΔpyrF突变株的表达及pLD-ZsG的遗传稳定性。实验结果表明,原养型ZsGreen阳性转化子可在普通Elliker培养基中正常生长,在荧光显微镜下观察到明显的绿色荧光信号;此外,PCR和Western blotting也证实ZsGreen能在NZ3900中表达且能稳定传代至30代,说明pLD食品级表达载体构建成功且使得外源蛋白在L. lactis中稳定表达。综上所述,基于pyrF营养...     

食品级微乳液的研究进展

微乳液(microemulsion,简称ME)是由两种互不相溶的溶剂形成的热力学稳定体系,在医药、化妆品以及采油等领域都有广泛的应用,但在食品领域的研究还比较少。研究表明微乳液能够提高亲水性或亲脂性物质的溶解度,并能作为化学或酶法反应的有效介质,引起了广大食品领域科学工作者的关注。本文对食品级微乳液的制备、增溶作用以及作为微反应器等进行了综述。     

乳酸菌食品级表达系统的研究进展

乳酸菌是一类广泛使用的工业菌.近几十年来,乳酸菌作为同源和异源蛋白表达的宿主菌的潜在应用已得到深入研究,在此基础上建立和发展了乳酸菌食品级基因表达系统.首先介绍了乳酸菌食品级表达系统的一些基本条件,表达和标记系统的适用原则,然后追踪其前沿应用进展情况,对乳酸菌食品级基因表达系统的最新应用进行了归纳,根据此表达系统在当前食品经济中的位置,对其在食品工业、医药和保健品等领域的应用前景进行了展望.     

食品级Pickering乳状液稳定剂研究进展

该文阐述Pickering乳状液的质构构建及稳定性影响因素,重点论述生物大分子固体颗粒的种类及其稳定Pickering乳状液的机理。高分子生物聚合物因具有低细胞毒性、易被降解、生物兼容性和利用率高的优点,成为食品领域制备Pickering乳状液固体颗粒的良好材料。蛋白质具有亲水-亲油的双亲结构特性,可以吸附在油-水界面上,降低界面的自由能,同时也能够在界面上形成一层厚的立体阻隔层,防止乳状液液滴的聚结从而稳定乳状液。多糖类包括淀粉、甲壳素以及一些纤维素及其衍生体,也可以用来制备固体颗粒稳定剂,但多糖类偏亲水,因此可以通过一定的改性,如接入疏水基团,使多糖在油-水界面上达到亲水-亲油平衡。另外多糖由于其带电性质,可以通过静电排斥作用,防止液滴的聚集,从而稳定乳状液。蛋白与小分子乳化剂、多糖与小分子乳化剂、蛋白质与多糖在一定的pH值、离子强度、温度等条件下产生协同增效作用,形成聚合体颗粒,也可有效地稳定Pickering乳状液。     

一种新型食品级表达载体pLEB590表达小鼠mCu/ZnSOD的初步研究

采用RT-PCR技术从小鼠肝脏总RNA扩增0.46kb的小鼠铜锌超氧化物歧化酶基因的cDNA序列,首先T-A克隆至大肠杆菌表达质粒pUC19,进行序列测定。再将mCu/ZnSOD cDNA亚克隆至以nisⅠ为食品级选择标记的乳酸乳球菌表达载体pLEB590中,用电穿孔法将重组质粒pLEB590-mCu/ZnSOD转化到乳酸乳球菌MG1614中,经SDS-PAGE和Westernblotting检测,获得了mCu/ZnSOD的组成型表达,并通过SOD酶活测定表明该重组菌表达的mCu/ZnSOD具有较好的生物活性。     

乳酸菌食品级质粒及应用的研究进展

乳酸菌是食品发酵工业中重要的益生菌,利用分子生物学技术构建的菌种对食品产业发展及人类健康具有重要影响。本文主要通过介绍乳酸菌食品级系统的基本要求、食品级质粒的元件组成、食品级质粒构建策略及其应用的研究进展,展示了乳酸菌食品级分子操作系统的建立对乳酸菌的深层次开发利用所具有的重要意义。     

食品级乳酸菌基因表达系统的研究进展

本文从乳酸基因工程菌、载体选择标记和表达系统的构建方面介绍食品级乳酸菌表达系统,以及乳酸菌基因表达系统的应用前景。     

食品级乳酸工程菌的研究进展

简要概述了乳酸菌控制表达体系的研究现状,总结了食品级乳酸工程菌的研究进展,提出了今后的研究方向及其应用前景。     

乳酸菌两组分食品级选择标记复制子缺失质粒的构建

乳酸菌NICE系统的两组分食品级选择标记具有显性和互补选择标记的优点。含红霉素抗性选择标记的复制子缺失的伴生型质粒是依赖复制子完全且无选择标记的食品级克隆载体而复制的。构建的伴生型质粒的Emr和rep分别来源于pMG36e和pRAF800,经酶切、缺刻、补平和连接得到只能在红霉素选择压力下与θ型复制子的克隆载体共存的复制子缺失伴生型质粒。     

Expression Cassettes for Formaldehyde and Fluoroacetate Resistance,Two Dominant Markers in Saccharomyces cerevisiae

We employed two genes in constructing yeast expression cassettes for dominant, selectable markers. The Saccharomyces cerevisiae gene SFA1, encoding formaldehyde dehydrogenase, was placed under the control of the GPD1 promoter and CYC1 terminator. The Moraxella sp. strain B gene dehH1, encoding fluoroacetate dehalogenase, was placed under the control of both the GPD1 and CYC1 promoters. With these constructs it was possible to select directly for yeast strains resistant to either formaldehyde or fluoroacetate. Both selective agents are completely metabolized and inexpensive, making them very useful in the pursuit of yeast gene functions and for industrial applications. An additional advantage of the formaldehyde dehydrogenase marker is that it is an S. cerevisiae gene, thus allowing ‘all yeast’ constructs. © 1997 John Wiley & Sons, Ltd.     

Food-grade carrageenans and their implications in health and disease

Food additives, often used to guarantee the texture, shelf-life, taste, and appearance of processed foods, have gained widespread attention due to their increased link to the growing incidence of chronic diseases. As one of the most common additives, carrageenans have been used in human diets for hundreds of years. While classified as generally recognized as safe (GRAS) for human consumption, numerous studies since the 1980s have suggested that carrageenans, particularly those with random coil conformations, may have adverse effects on gastrointestinal health, including aggravating intestinal inflammation. While these studies have provided some evidence of adverse effects, the topic is still controversial. Some have suggested that the negative consequence of the consumption of carrageenans may be structure dependent. Furthermore, pre-existing conditions may predispose individuals to varied outcomes of carrageenan intake. In this review, structure–function relationships of various carrageenans in the context of food safety are discussed. We reviewed the molecular mechanisms by which carrageenans exert their biological effects. We summarized the findings associated with carrageenan intake in animal models and clinical trials. Moreover, we examined the interactions between carrageenans and the gut microbiome in the pathogenesis of gastrointestinal disorders. This review argues for personalized guidance on carrageenan intake based on individuals’ health status. Future research efforts that aim to close the knowledge gap on the effect of low-dose and chronic carrageenan intake as well as interactions among food additives should be conducive to the improved safety profile of carrageenans in processed food products.     

Simple Sequence Repeat Markers in Genetic Divergence and Marker-Assisted Selection of Rice Cultivars: A Review

Sequencing of rice genome has facilitated the understanding of rice evolution and has been utilized extensively for mining of DNA markers to facilitate marker-assisted breeding. Simple sequence repeat (SSR) markers that are tandemly repeated nucleotide sequence motifs flanked by unique sequences are presently the maker of choice in rice improvement due to their abundance, co-dominant inheritance, high levels of allelic diversity, and simple reproducible assay. The current level of genome coverage by SSR markers in rice is sufficient to employ them for genotype identification and marker-assisted selection in breeding for mapping of genes and quantitative trait loci analysis. This review provides comprehensive information on the mapping and applications of SSR markers in investigation of rice cultivars to study their genetic divergence and marker-assisted selection of important agronomic traits.     

食品纳米技术与纳米食品研究进展

纳米微粒在常态下能表现出普通物质不具有的特性,这使纳米材料和纳米技术极具潜力、倍受瞩目。在食品领域,纳米食品加工技术、纳米营养素制备技术、纳米食品包装、纳米检测技术成为研究热点。本文综述了食品纳米技术与纳米食品最新研究进展与成果,提出了食品纳米技术与纳米食品今后研究的前沿科学问题与需要突破的关键技术。     

分子标记及其在甘蔗育种中的应用

本文综述了几种分子标记在甘蔗育种上的应用，以及对提高甘蔗育种的研究水平和促进甘蔗生产所具有的重要意义。     

Dominant marker vectors for selecting yeast mating products

We have developed plasmid vectors to enable selection of diploids from mating reactions between haploid strains that lack compatible recessive genetic markers. The plasmids bear one of five different dominant selectable markers, kanMX4, hphMX4, natMX4, patMX3 or ZEO, a yeast origin of replication, and the URA3 gene. Diploids can be selected from mating reactions between haploids transformed with plasmids expressing different dominant markers, by using a combination of drugs that select for both markers. Following non-selective growth, diploids that subsequently become cured of the plasmids can be directly selected on 5-FOA, for ura3 auxotrophs, or identified by replica-plating onto appropriate selective media.     

共显性RAPD标记的检测及应用

将４２个ＲＡＰＤ标记应用于杂交稻组合的Ｆ２群体的１０８个单株进行检测,结果表明：在２个座位分别有２对标记呈共显性分离。这种共显性的ＲＡＰＤ标记可以快速、准确地确定Ｆ２代植株的基因型。     

食品的微生物保鲜技术

在人们对食品卫生要求越来越高的今天，食品的保鲜技术正悄然发生着一场革命性的变化。传统的食品保鲜技术将逐步被一种全新、无毒、高效的保鲜技术-微生物保鲜技术所取代。本文综述了常用于食品保鲜的微生物种类，微生物处理方法及保鲜机理，对目前国内外食品的微生物保鲜研究作了简单的概述。     

食源性致病菌RPA检测技术研究进展

食源性致病菌是食品安全的重要隐患,开发针对食源性致病菌快速、有效的检测技术迫在眉睫。在诸多食源性致病菌检测手段中,重组酶聚合酶扩增技术(RPA),因具有比传统分子及免疫学检测技术如聚合酶链式反应(PCR)、实时荧光定量PCR、酶联免疫吸附技术(ELISA)等更快速、灵敏、特异、简便以及实用性强等方面优势,现已在一定程度上得到应用。本文将对RPA技术原理及其衍生技术包括直接重组酶聚合酶扩增技术(Direct-RPA)、重组酶聚合酶扩增侧流层析技术(RPA-LFD)、重组酶聚合酶扩增酶联免疫吸附技术(RPA-ELISA)、实时重组酶聚合酶扩增技术(Real-time RPA)、RPA微流体等技术进行简要综述。