安全的天然食品防腐剂细菌素

细菌素是细菌产生的可以杀死或抑制别的细菌生长的抗菌蛋白。许多乳酸菌(LAB)产生各种各样的细菌素，其中的尼生素是唯一的在食品中作为防腐剂广泛使用的细菌素。文章综述了以尼生素为重点对细菌素与抗生素的区别、活性细菌素分子的形成以及其在食品中的应用，并比较了这两种类型的分子的合成、作用模式、抵抗力和安全性。     

Bacteriocins and their Food Applications

Over the last 2 decades, a variety of bacteriocins, produced by bacteria that kill or inhibit the growth of other bacteria, have been identified and characterized biochemically and genetically. This review article focuses on the ecology of bacteriocins, determination of bacteriocin activity, biosynthesis of bacteriocins, and mode of action. Bacteriocin production and modeling are discussed in the article. Nisin is discussed in some detail in this article since it is currently the only purified bacteriocin approved for food use in the U.S. and has been successfully used for several decades as a food preservative in more than 50 countries. For activity spectra and food applications, the review article focuses primarily on class I and class IIa bacteriocins produced by lactic acid bacteria (LAB) given their development as food preservatives.     

Development of Wide-Spectrum Hybrid Bacteriocins for Food Biopreservation

The food industry demands new procedures and methods to produce minimally processed, ready to eat food with intact nutritional, taste, and flavor properties. The biopreservation and the use of both bacteriocins produced by lactic acid bacteria (LAB) and bacteriocinogenic strains as an alternative to substitute chemical antimicrobial for food preservation became increasingly important in the last two decades. When the new proposed natural preservatives techniques are applied, probiotics food can be obtained and, simultaneously, foodborne pathogens and spoilage contaminants can diminish. However, bacteriocins produced by LAB have a narrow antibacterial spectrum and are inactive against Gram-negative bacteria like Salmonella and the emergent enterohemorrhagic Escherichia coli. Knowing the mechanism of action and the structural features of microcins synthesized by Gram-negative bacteria and with potent antimicrobial activity against the mentioned microorganism, the proposal is to obtain hybrid peptides (microcin–bacteriocin) with broad antimicrobial spectrum. This review explains how the inability of bacteriocins to cross the outer membrane of Gram-negative bacteria unable them to act on the bacteria. It will also be discussed how a hybrid bacteriocin can be obtained.     

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。     

乳酸菌细菌素分类与作用机制

乳酸菌细菌素作为天然的食品防腐剂,可抑制或杀灭食品中致病微生物和腐败微生物从而保护食品的安全。文中介绍了乳酸菌细菌素传统分类方法和新提出的分类方法,并且综述了乳酸菌细菌素的作用机制。     

提高乳酸菌细菌素合成量方法的研究进展

细菌素是某些细菌通过核糖体合成机制产生的蛋白质或多肽,能够抑制与其亲源关系相同或相近的微生物,某些细菌素在食品加工和发酵过程中能抑制致病菌和腐败菌。乳酸菌被认为是一般公认安全,其细菌素具有安全性高、稳定性好、抑菌谱广等优点,作为一种新型食品防腐剂备受关注,但商品化的乳酸菌细菌素十分有限,仅限于Nisin和Pediocin PA-1等少数几种,合成量低是细菌素在食品中应用受限的主要原因之一。从不同原料中筛选高产菌株、发酵培养基和发酵条件优化、诱变育种、原生质体融合、基因工程方法、群体感应系统调控六个方面,论述了增加乳酸菌细菌素合成量的方法,以期为实现乳酸菌细菌素的工业化生产提供一定的借鉴。     

Incidence and antibiotic susceptibility of bacteriocin‐producing lactic acid bacteria from dairy products

Screening for bacteriocin production by strains of lactic acid bacteria (LAB) from local dairy products in Iran resulted in the detection of 10 bacteriocin‐producing strains. Among 105 isolated, 10 bacteriocin producers were phenotypically and genotypically identified as Enterococcus spp. The antimicrobial compounds produced by these novel strains were inactivated by trypsin, proteinase k. These bacteriocins also were active in a wide range of pH and temperature values, and inhibited not only the closely related LAB, but also Listeria monocytogenes.     

Heterologous production of bacteriocins by lactic acid bacteria

Over the last two decades, bacteriocins produced by lactic acid bacteria (LAB) have been the subject of considerable research and industrial interest due to their potential as food biopreservatives. The development of heterologous expression systems for such antimicrobial compounds may offer a number of advantages over native systems, such as facilitating the control of bacteriocin gene expression or achieving higher production levels. In addition, the heterologous production by food-grade LAB offers an attractive method for overcoming some of the adverse situations that may affect the effectiveness of some bacteriocins in food systems. Construction of multibacteriocinogenic strains or acquisition of antimicrobial properties by industrial strains are further objectives that can be achieved through the use of heterologous gene expression systems. The development of new biotechnological tools and recent advances in LAB genetics account for the escalating number of studies dealing with heterologous production of bacteriocins by such hosts. This paper reviews the literature published on the subject and compares the different experimental strategies that have been used up to the present for this purpose.     

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.     

Physical and nutritional conditions for optimized production of bacteriocins by lactic acid bacteria – A review

ABSTRACT

There has been an increasing debate about the use of synthetic chemical compounds and the consequences of their use in food preservation. In this context, the utilization of some natural compounds produced by bacteria, showing an inhibitory effect against microorganisms associated with food contamination, have gained attention as preservation technology. In order to improve the production and yield costs of bacteriocins, detailed studies are necessary to determine the conditions that allow an optimized production and extraction of bacteriocins from lactic acid bacteria (LAB). In this context, this article aims to discuss the information regarding the main factors that influence bacteriocin production by LAB. The biosynthesis of bacteriocins can be influenced by various culture conditions, such as the composition of the medium, pH, temperature and growth kinetics of the microorganisms. One of the limiting factors for the use of bacteriocins on a large scale in food preservation is the economic factor. In order for the production costs of bacteriocins to be reduced, making them attractive, it is necessary to know the optimum parameters of production, thus maximizing productivity and making costs more attractive.     

乳酸菌细菌素研究进展及其在水产养殖和加工中的应用

乳酸菌细菌素是一种由乳酸菌在核糖体内合成、具有抑菌活性的多肽或蛋白质。由于乳酸菌通常被认为是安全的微生物,因此由它产生的细菌素受到了广泛地关注。目前由于大部分乳酸菌细菌素抑菌机理研究还不够深入,在一定程度上限制了它的发展和应用。本文对现有乳酸菌细菌素研究成果进行总结,并对细菌素进行了系统分类,阐述了各类乳酸菌细菌素对革兰氏阳性菌的作用机理,最后介绍了乳酸菌细菌素在水产养殖、水产品加工贮藏过程中的应用,旨在为乳酸菌细菌素的应用提供新的探索和基础理论依据。     

Detection and preliminary characterization of a bacteriocin (plantaricin 35d) produced by a Lactobacillus plantarum strain

Lactic acid bacteria (134) from Italian sausages were tested for the production of antimicrobial substances (bacteriocins). Six percent of these showed antibacterial activity against one or several closely related microorganisms used as indicators. Lactobacillus plantarum 35d in particular produced a bacteriocin of high activity (320 AU ml(-1)) and a wide range of antimicrobial activity including S. aureus, L. monocytogenes, and A. hydrophila. The bacteriocin withstood heating at 80 degrees C for 120 min and storage at 4 degrees C for 6 months. The mode of action was identified as bactericidal. The apparent molecular weight of the bacteriocin extracted with n-butanol was estimated to be 4.5 kDa.     

Lactobacillus salivarius: Bacteriocin and probiotic activity

Lactic acid bacteria (LAB) antimicrobial peptides typically exhibit antibacterial activity against food-borne pathogens, as well as spoilage bacteria. Therefore, they have attracted the greatest attention as tools for food biopreservation. In some countries LAB are already extensively used as probiotics in food processing and preservation. LAB derived bacteriocins have been utilized as oral, topical antibiotics or disinfectants. Lactobacillus salivarius is a promising probiotic candidate commonly isolated from human, porcine, and avian gastrointestinal tracts (GIT), many of which are producers of unmodified bacteriocins of sub-classes IIa, IIb and IId. It is a well-characterized bacteriocin producer and probiotic organism. Bacteriocins may facilitate the introduction of a producer into an established niche, directly inhibit the invasion of competing strains or pathogens, or modulate the composition of the microbiota and influence the host immune system. This review gives an up-to-date overview of all L. salivarius strains, isolated from different origins, known as bacteriocin producing and/or potential probiotic.     

FUNDAMENTALS AND PERSPECTIVES FOR THE USE OF BACTERIOCINS PRODUCED BY LACTIC ACID BACTERIA IN MEAT PRODUCTS

Bacteriocins of lactic acid bacteria (LAB) are proteinaceous compounds that may present antimicrobial activity towards important foodborne pathogens and spoilage-related microflora. Due to these properties, bacteriocin-producing strains or purified bacteriocins have a great potential of use in biologically based food preservation systems. Despite the growing number of articles describing the isolation of bacteriocinogenic strains, genetic determinants for production, as well as the purification and biochemical characterization of these inhibitory substances, there are only limited reports of successful application of bacteriocins to meats.

This paper presents a critical review of the methods available for screening of bacteriocin-producing LAB strains from meats and also discusses the proposed mechanisms of action for LAB bacteriocins. Additionally, an overview of the Brazilian experience in the application of LAB bacteriocins to meats and meat products is given.     

FUNDAMENTALS AND PERSPECTIVES FOR THE USE OF BACTERIOCINS PRODUCED BY LACTIC ACID BACTERIA IN MEAT PRODUCTS

Bacteriocins of lactic acid bacteria (LAB) are proteinaceous compounds that may present antimicrobial activity towards important foodborne pathogens and spoilage-related microflora. Due to these properties, bacteriocin-producing strains or purified bacteriocins have a great potential of use in biologically based food preservation systems. Despite the growing number of articles describing the isolation of bacteriocinogenic strains, genetic determinants for production, as well as the purification and biochemical characterization of these inhibitory substances, there are only limited reports of successful application of bacteriocins to meats.

This paper presents a critical review of the methods available for screening of bacteriocin-producing LAB strains from meats and also discusses the proposed mechanisms of action for LAB bacteriocins. Additionally, an overview of the Brazilian experience in the application of LAB bacteriocins to meats and meat products is given.     

Pediocin PA-1的结构、生物合成与作用机制

乳酸菌素是乳酸菌通过核糖体合成机制产生的一类具有生物活性的蛋白质、多肽或前体多肽.最近将乳酸菌素分为三大类,其中Ⅱ a类类片球菌素是研究的热点,它的典型代表是Pediocin PA-1.Pedioein PA-1具有较强的抗单增李斯特菌特性和热稳定性,是一种具有广阔应用前景的食品添加剂.本文综述了Pediocin PA-1的结构、生物合成和作用机制,概述了国内外对Pediocin PA-1的研究进展和发展方向,以期对细菌素的深入研究和广泛应用起到抛砖引玉的作用.     

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.     

Preservation and fermentation: past,present and future

Preservation of food and beverages resulting from fermentation has been an effective form of extending the shelf-life of foods for millennia. Traditionally, foods were preserved through naturally occurring fermentations, however, modern large scale production generally now exploits the use of defined strain starter systems to ensure consistency and quality in the final product. This review will mainly focus on the use of lactic acid bacteria (LAB) for food improvement, given their extensive application in a wide range of fermented foods. These microorganisms can produce a wide variety of antagonistic primary and secondary metabolites including organic acids, diacetyl, CO2 and even antibiotics such as reuterocyclin produced by Lactobacillus reuteri. In addition, members of the group can also produce a wide range of bacteriocins, some of which have activity against food pathogens such as Listeria monocytogenes and Clostridium botulinum. Indeed, the bacteriocin nisin has been used as an effective biopreservative in some dairy products for decades, while a number of more recently discovered bacteriocins, such as lacticin 3147, demonstrate increasing potential in a number of food applications. Both of these lactococcal bacteriocins belong to the lantibiotic family of posttranslationally modified bacteriocins that contain lanthionine, beta-methyllanthionine and dehydrated amino acids. The exploitation of such naturally produced antagonists holds tremendous potential for extension of shelf-life and improvement of safety of a variety of foods.     

Characterization of semipurified enterocins produced by Enterococcus faecium strains isolated from raw camel milk

Food safety has become an issue of great interest worldwide. Listeria monocytogenes is a food-borne pathogen that causes listeriosis and is difficult to control in the dairy industry. The use of lactic acid bacteria (LAB) and their antimicrobial substances against Listeria is promising in food applications. Here, we report the isolation from raw camel milk of LAB displaying antilisterial activity. Two isolates were selected for their secretion of bacteriocin(s) and identified by 16S rRNA sequencing as Enterococcus faecium S6 and R9. The produced bacteriocins were partially purified by ammonium sulfate precipitation and then biochemically characterized. Antimicrobial activity was estimated to be 6,400 and 400 AU (arbitrary units)/mL for E. faecium S6 and R9, respectively. The proteinaceous nature of the bacteriocins was confirmed via enzymatic reactions. Moreover, lipolytic and glycolytic enzymes completely inactivated the antimicrobial effect of the bacteriocins. These bacteriocins were heat-resistant and stable over a wide range of pH (2.0 to 10.0). To confirm its inactivation by lipolytic and glycolytic enzymes, the bacteriocin of E. faecium S6 was further purified by gel filtration, which suggested the existence of carbohydrate and lipid moieties. In addition, enterocin-coding genes were identified by PCR, showing DNA fragments corresponding in size to enterocins A, B, and P for E. faecium S6 and to enterocins B and P for E. faecium R9. In conclusion, these results indicate that partially purified bacteriocins from E. faecium S6 and R9 may be beneficial in controlling Listeria in the dairy industry.