双肽（IIb类）细菌素的结构特点及其与功能的关系

双肽（IIb类）细菌素通常是由革兰氏阳性菌产生的热稳定小分子（＜10 kDa）双组分抗菌肽,该类肽能够依靠特定模式基序介导肽-肽互作,形成具有跨膜能力的活性二聚体蛋白。大量研究表明,双肽细菌素具有可靠的安全性和理想的抑菌效果,在耐药菌控制方面有着巨大的应用潜力。因此,双肽细菌素发挥功能的结构特征与作用机制受到研究者们的广泛关注。本文按照双肽细菌素结构形成、肽-肽互作及肽-膜互作的逻辑梳理该类抗菌肽发挥抑菌作用的机制,同时综合现有研究阐述双肽细菌素的结构规律及影响其活性的结构要点,以期为双肽细菌素的相关研究提供新的思路。     

群体感应系统在乳酸菌产细菌素中的作用

许多乳酸菌能够产生抗菌活性肽——细菌素,细菌素具有不同的结构、作用方式、抑菌谱和效价,通常认为乳酸菌和其所产的细菌素都是安全的,乳酸菌所产细菌素作为天然食品防腐剂已显示了巨大的潜能。基于群体感应的细胞间交流已成为细菌素合成的关键调控机制,群体感应作为细胞密度函数,可使细菌素产生保持同步性。群体感应需通过信号分子介导感知菌体密度,信号分子随着菌体密度增加而增加,并激活信号转导级联使菌体产生细菌素。本文通过对乳酸菌群体感应信号分子种类、信号转导机制及群体感应系统对两类细菌素合成的调控进行综述,以初步了解群体感应系统在乳酸菌产细菌素过程中的作用机制。     

植物乳杆菌素研究进展

植物乳杆菌素是植物乳杆菌产生的一类具有抑菌活性的肽类，可以抑制许多革兰氏阳性菌。作者简述了细菌素的分类、植物乳杆菌素的抑菌范围和抑菌机制，并简要介绍了几种植物乳杆菌素的性质。尽管目前植物乳杆菌素还未被批准作为防腐剂在食品中使用，但植物乳杆菌已被广泛地应用到食品工业中，相信不久的将来植物乳杆菌素作为一类理想的天然食品防腐剂，应用前景将十分广阔。     

产类细菌素乳酸菌筛选及类细菌素的特性

从泡菜中分离到一株产生类细菌素的乳酸菌,通过双层平板扩散试验测试这种类细菌素的抑菌活性,并且研究其部分生物学特性.经形态特征、生理生化特征和API试剂条鉴定,该菌为植物乳杆菌(Lactobacillus plantarum).产生的类细菌素对所试菌株具有明显的抑制作用,排除有机酸、过氧化氢和糖类的干扰后,仍有抑菌活性.这种类细菌素对热、酸碱稳定,微量的K+,Mn2+,Mg2+能增强其抑菌活性,Fe2+和Cu2+能减弱活性;可被4种蛋白酶失活,表明这种类细菌素是一种蛋白质活性物质.该类细菌素的作用方式是杀菌,抑菌谱广,可抑制多种革兰氏阳性细菌、革兰氏阴性细菌和真菌的生长.     

乳酸菌细菌素生物合成机制、抑菌机制及应用研究进展

细菌素具有抗食源性致病菌和食品腐败菌的特点,可以作为在食品中应用的天然、无毒抗菌剂。但由于细菌素的抑菌机制复杂多样,尚未完全解析,以及抑菌效果受诸多因素影响,导致在食品领域的实际应用十分有限。该文将对细菌素的筛选和鉴定方法、抑菌机制及包埋技术的最新研究进展进行综述,以促进细菌素的研究和应用。     

瑞士乳杆菌产生的细菌素的抑菌活性研究

主要通过研究对从建昌板鸭发酵过程中分离瑞士乳杆菌产生细菌素的抑菌活性,考察不同温度,不同p H,不同种类酶作用对细菌素抑菌活性的影响。结果证明:蛋白酶能一定程度抑制细菌素的抑菌活性,且胰蛋白酶的抑制程度最强;该细菌素的抑菌活性对温度的耐受力强,即使在100℃处理后仍具有抑菌活性,在-20℃条件下保存时抑菌活性最强;该细菌素p H在1.5~4.0时具有抑菌活性,在p H为1.5时抑菌活性最强。     

一株后生元菌株的抑菌特性研究及其细菌素基因簇的挖掘

本文旨在筛选一株可拮抗中国大鲵源嗜水气单胞菌的后生元菌株,并对其进行抑菌特性的研究和细菌素基因簇的挖掘。以中国大鲵病原性嗜水气单胞菌（Aeromonas hydrophila, Ah2）为指示菌,筛选一株产细菌素乳酸菌株并评估其药敏特性;采用有机溶剂萃取法初步纯化菌株产细菌素;通过pH、温度和消化酶耐受性、贮藏稳定性、抑菌谱及最小抑菌（MIC）和杀菌浓度（MBC）共六类指标评价细菌素的抑菌特性;溶血反应与细胞毒性实验测试细菌素对Ah2的抑菌效果,经扫描电子显微镜初步探究细菌素的抑菌机制;经由紫外全波长扫描定性细菌素以及Tricine-SDS-PAGE电泳测定细菌素的分子量范围;最后根据菌株的全基因组序列挖掘其潜在的细菌素基因簇（RiPPs）。结果显示,从青岛市售腐乳中筛出一株产细菌素植物乳植物杆菌M4L1（Lactiplantibacillus plantarum M4L1）。初步纯化M4L1产细菌素并命名为LP01。细菌素LP01具备良好的消化酶耐受性,且在pH2~10、?20~121 ℃和9个月贮藏期内均表现出稳定的抑菌活性,并对单增李斯特菌、弗氏柠檬酸杆菌等14株革兰氏阳性和阴性菌均有不同程度的抑制作用;另外,LP01对Ah2的MIC和MBC分别为12.94和25.88 μg/mL。经MBC浓度的LP01处理后的Ah2,溶血活性和细胞毒性均得到明显缓解;SEM观察其通过破坏Ah2的细胞壁具有抑制或杀伤作用。LP01在波长200~220 nm处的肽类特征吸收峰显著,电泳后条带显示其分子量在3.3~4.0 kDa,LP01为小分子肽类细菌素。此外,基因注释到M4L1有2个细菌素基因簇（RiPPs）,对应产物分别为Plantaricin K和Plantaricin E,均属于植物乳杆菌II类细菌素。菌株M4L1不仅含有多种抗菌物质相关基因簇,而且其细菌素LP01具备了优良的抑菌性能,能有效抑制多种水产病原菌、食物腐败菌及食源性致病菌等。产细菌素植物乳植物杆菌M4L1作为一株潜在的后生元菌株具有较好的应用前景。     

一株乳酸乳球菌所产细菌素的生物学特性

对乳酸乳球菌KLDS4.0326所产类细菌素进行分离纯化,并对细菌素的部分生物学特性进行研究。在排除酸性产物和过氧化氢的干扰后,菌株的无细胞发酵上清液对金黄色葡萄球菌和枯草芽孢杆菌等革兰氏阳性细菌以及大肠杆菌、沙门氏菌等革兰氏阴性细菌具有显著的抑制作用;经胰蛋白酶、胃蛋白酶、木瓜蛋白酶和蛋白酶K处理后,抑菌活性降低,表明抑菌成分为蛋白类物质;该细菌素具有良好的热稳定性,在酸性条件下抑菌活性稳定,并且具有较广的抑菌谱,能够抑制多种革兰氏阳性细菌和革兰氏阴性细菌。     

植物乳杆菌MXG-68所产细菌素的抑菌特性分析

研究乳酸菌细菌素的抑菌特性,为其作为生物防腐剂奠定基础。以酸马奶来源的植物乳杆菌MXG-6所产的细菌素为研究对象,对其抑菌谱、作用方式、相对分子质量及耐受性进行分析。该细菌素对革兰氏阳性菌和革兰氏阴性菌均具有抑菌活性,属于广谱细菌素,作用方式为杀菌,而不是抑菌和溶菌。变性聚丙烯酰胺凝胶电泳法(SDS-polyacrylamide gels electrophoresis,SDS-PAGE)确定植物乳杆菌MXG-6所产细菌素的分子质量约6 ku。60、80、100、121℃处理30 min及4、-20℃处理30 d对抑菌活性影响不显著(P 0. 05),在pH 1～10均表现出抑菌活性,表明细菌素具有较好的温度耐受性和酸碱耐受性。有机溶剂及表面活性剂对细菌素的抑菌活性基本无影响(P 0. 05),而EDTA有利于提高抑菌活性。细菌素的抑菌特性分析可为更好地实现细菌素的开发及应用提供一定的理论依据。     

Ⅱ类细菌素的生物合成及其在食品领域的应用

乳酸菌细菌素是乳酸菌核糖体合成的具有抑菌或杀菌活性的多肽或者蛋白质。其中,Ⅱ类细菌素具有较宽的抑菌谱和较高的抑菌活性,然而,由于其自然条件下产量低且合成调控机理的研究较少,目前尚未实现规模化生产。为了解和掌握Ⅱ类细菌素的合成及调控机理,本文分类阐释此类细菌素几个亚群的编码基因结构、多肽结构,以及杀菌、免疫和调节机理,并阐述Ⅱ类细菌素在食品防腐和保鲜等方面的应用。     

Mining,heterologous expression,purification, antibactericidal mechanism,and application of bacteriocins: A review

Bacteriocins are generally considered as low-molecular-weight ribosomal peptides or proteins synthesized by G⁺ and G⁻ bacteria that inhibit or kill other related or unrelated microorganisms. However, low yield is an important factor restricting the application of bacteriocins. This paper reviews mining methods, heterologous expression in different systems, the purification technologies applied to bacteriocins, and identification methods, as well as the antibacterial mechanism and applications in three different food systems. Bioinformatics improves the efficiency of bacteriocins mining. Bacteriocins can be heterologously expressed in different expression systems (e.g., Escherichia coli, Lactobacillus, and yeast). Ammonium sulfate precipitation, dialysis membrane, pH-mediated cell adsorption/desorption, solvent extraction, macroporous resin column, and chromatography are always used as purification methods for bacteriocins. The bacteriocins are identified through electrophoresis and mass spectrum. Cell envelope (e.g., cell permeabilization and pore formation) and inhibition of gene expression are common antibacterial mechanisms of bacteriocins. Bacteriocins can be added to protect meat products (e.g., beef and sausages), dairy products (e.g., cheese, milk, and yogurt), and vegetables and fruits (e.g., salad, apple juice, and soybean sprouts). The future research directions are also prospected.     

乳酸菌细菌素抑菌特性及在食品中的应用研究进展

乳酸菌细菌素是细菌在核糖体上合成的具有抗菌活性的多肽类物质,这些细菌素能杀灭或抑制引起食品腐败的细菌的繁殖,可作为天然的食品防腐剂在食品中应用。该文综述了乳酸菌细菌素的分类、国内外研究现状、抑菌特性及应用等方面的最新研究进展,并对乳酸菌细菌素未来研究趋势进行简要分析,对乳酸菌细菌素在食品中的应用有一定参考价值。     

Lactobacillus acidophilus: Characterization of the Species and Application in Food Production

L. acidophilus is a homofermentative, microaerophilic, short chain gram positive microorganism with rod morphology having its bacteriocins belonging to class II a. Several bacteriocins of L. acidophilus have been isolated and characterized. These are structurally similar, but their molecular weight varies as well as their spectrum of antimicrobial activity. They exhibit important technical properties, i.e., thermostability and retaining of activity at a wide pH range along with strong inhibitory actions against food spoilage and pathogenic bacteria make them an important class of biopreservatives. L. acidophilus can be added as an adjunct in many food fermentation processes contributing to unique taste, flavor, and texture. It also preserves the products by producing lactic acid and bacteriocins. A lot of new information regarding the bacteriocins of L. acidophilus has emerged during the last few years. In this review, an attempt has been made to summarize and discuss all the available information regarding the sources of bacteriocins production, their characteristics, and their antimicrobial action along with their application.     

乳链菌肽(Nisin)研究进展

乳链茵肽(Nisin)是细菌素中一种应用最广泛的高效、无毒天然食品防腐剂。本文简要介绍了Nisin的研究过程、结构特性、防腐机理、在食品防腐保鲜中的应用及今后的发展前景。     

Class IIa bacteriocins from lactic acid bacteria: antibacterial activity and food preservation

In the last decade, a variety of ribosomally synthesized antimicrobial peptides, or bacteriocins, produced by lactic acid bacteria have been identified and characterized. As a result of these studies, insight has been gained into various fundamental aspects of biology and biochemistry such as bacteriocin processing and secretion, mechanisms of cell immunity, and structure-function relationships. In parallel, there has been a growing awareness that bacteriocins may be developed into useful antimicrobial food additives. Class IIa bacteriocins can be considered as the major subgroup of bacteriocins from lactic acid bacteria, not only because of their large number, but also because of their significant biological activities and potential applications. The present review provides an overview of the knowledge available for class IIa bacteriocins and discusses common features and recent findings concerning these substances. The activity and potential food applications of class IIa bacteriocins are a major focus of this review.     

Inhibition of Cronobacter sakazakii by Heat Labile Bacteriocins Produced by Probiotic LAB Isolated from Healthy Infants

Cronobacter sakazakii is an opportunistic pathogen that can cause bacteremia, meningitis, and necrotizing enterocolitis, most often in neonates with case‐fatality rates that may reach 80%. The antimicrobial activity of lactic acid bacteria against a wide range of foodborne pathogens is well‐established in different types of food products. The objective of the current study was to investigate the antibacterial activity of Lactobacillus acidophilus and L. casei isolated from feces of healthy infants against different strains of C. sakazakii in agar and a rehydrated infant milk formula (RIMF) model. The inhibition zones of C. sakazakii around L. acidophilus or L. casei ranged from 22 to 32 mm on eMan Rogosa Sharpe (MRS) agar under aerobic conditions, while a slight reduction in antibacterial activity was noted on modified MRS (0.2% glucose) under anaerobic conditions. It was observed that pH‐neutralized cell‐free supernatant (CFS) of L. acidophilus or L. casei was inhibitory against tested C. sakazakii strains. The inhibition zones of neutralized CFS were lower than the antibacterial activities of live cultures. The antibacterial activity of CFS was abolished when CFS from L. acidophilus or L. casei was heated at 60 or 80 °C for either 10 min or 2 h, or treated with trypsin or pepsin. This was considered strong evidence that the inhibition was due to the production of bacteriocins by L. casei and L. acidophilus. Both the CFS and active growing cells of L. casei and L. acidophilus were able to reduce the viability of C. sakazakii in the RIMF model. The results may extend the use of natural antimicrobials instead of conventional preservation methods to improve the safety of RIMF.     

Ⅱa类乳酸菌细菌素的异源表达研究进展

Ⅱa类乳酸菌细菌素由于其对单核细胞增生李斯特菌的强烈抑菌活性,已成为天然食品防腐剂研究与开发的热点。但是受生物合成调控系统控制,天然细菌素的产量往往很低而且提取过程较为复杂,很难满足相关研究和实际应用的需求。为此,许多研究者进行过Ⅱa类细菌素的异源表达研究,本文对该类细菌素在大肠杆菌、乳酸菌以及酵母菌中的异源表达研究作较为全面系统的综述,并指出目前存在的主要问题及今后的研究方向。     

Bacteriocins of lactic acid bacteria: Their potentials as food biopreservative

Abstract

Numerous strains of lactic acid bacteria used in the fermentation of foods are known to produce bacteriocins. In general, bacteriocins are a group of proteinaceous antimicrobial substances that inhibit the growth of closely related bacteria. However, some bacteriocins produced by lactic acid bacteria (LAB) exhibit a relatively broad antimicrobial spectrum and are active against several food‐spoilage and health‐threatening microorganisms. Many investigators have reported on the use of bacteriocins as food preservative to extend the shelflife of various foods. This review decribes the research that has been conducted on bacteriocinogenic lactic acid bacteria— isolated from a wide variety of foods and in some instances of animal origin—and the characteristics of bacteriocins. Special emphasis is placed on their potentials for use as food preservative and on their physicochemical nature, antibacterial spectrum, and genetic behavior.     

细菌素的抑菌机制及其在食品工业中应用进展

由致病菌等微生物污染所引起的食源性疾病和食品腐败变质始终是食品工业面临的巨大难题,而传统的抗生素防腐剂所产生的细菌耐药性会对人体健康造成潜在的威胁。出于人们对于安全和绿色防腐剂的巨大需求,细菌素的研究愈发成为焦点,以期发现可有效控制食源性病原体的新型抗菌物质。细菌素是细菌分泌的多肽或前体多肽,分子量在1~100 ku之间不均匀分布,可以杀死或抑制同一生态系统中竞争营养物质的敏感细菌,少数细菌素还表现出抗病毒和抗真菌等特性。已有研究发现的细菌素具有不同的作用模式,例如：成孔、抑制细胞壁/核酸/蛋白质合成等。该研究综述了细菌素的种类与抑菌作用机制,并结合最新的细菌素在食品工业上的应用,全面概述了细菌素抑菌的特性及其对未来食品行业的应用前景与展望,为细菌素更好的应用在食品工业中提供一定的理论依据,同时对推动食品防腐保鲜技术的革新发展具有重要的意义。     

乳酸菌细菌素抗菌潜力挖掘研究进展

乳酸菌产生的主要抗菌防腐物质是有机酸,但在乳酸菌代谢产物中发现了细菌素等其它抗菌物质,其中有的细菌素甚至具有强烈的抗真菌能力。世界范围内启动的乳酸菌基因组计划创造了巨大的生物信息流。乳酸菌基因组蕴含的生物信息将对研究乳酸菌细菌素的合成代谢途径,功能基因挖掘以及新型抗菌剂的开发搭建信息平台。结合乳酸菌细菌素的最新研究进展,讨论利用乳酸菌基因组探索乳酸菌的抗菌潜力及其作为生物防腐剂在食品保藏中的应用前景。