Charakterisierung einiger Bacteriocine im Hinblick auf mögliche Anwendungen im Lebensmittelbereich. 1. Mitt. Stammauswahl

Characterization of some bacteriocins with regard to possible applications in food industry. Part 1. Selection of strains. The ability to produce bacteriocins is common in all genera of lactic acid bacteria. Thirty-four out of 223 strains of lactic acid bacteria from the culture collection of the University Potsdam produced bacteriocins active against one or more indicator strains. Seventeen Gram-positive and Gram-negative strains, frequent occur as spoilage bacteria in food industry, were chosen as indicator strains, and 11 of them were inhibited by one or several bacteriocin producers. Most of the bacteriocin producers belong to the genera Enterococcus or Lactobacillus. Bacteriocins derived from Enterococcus faecium and Pediococcus acidilactici exhibited the widest inhibitory spectrum. The properties of Enterococcus faecium 10.051 and Enterococcus faecium 10.211 bacteriocins were further investigated to evaluate their potential use as natural food preservatives. The bacteriocin produced by Enterococcus faecium 10.211 exhibited a very wide inhibitory spectrum against food-spoiling strains. It was heat stable (100 °C for 60 min) and stable in a wide range of pH (1.2–10.0). The bacteriocin produced by Enterococcus faecium 10.051 showed a smaller inhibitory spectrum, and it was less stable against temperature and pH as the bacteriocin from strain 10.211. Both bacteriocins were inactivated by proteinase K. pronase E, and α-chymotrypsin. Bacteriocin from strain 10.211 will be the object of further investigations for application of bacteriocins in food industry.     

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。     

Potential of lactic acid bacteria isolated from specific natural niches in food production and preservation

Autochthonous strains of lactic acid bacteria (LAB) have been isolated from traditionally homemade cheeses collected from specific ecological localities across Serbia and Montenegro. Genetic and biochemical analysis of this LAB revealed that they produce bacteriocins, proteinases and exopolysaccharides. LAB produces a variety of antimicrobial substances with potential importance for food fermentation and preservation. Apart from the metabolic end products, some strains also secrete antimicrobial substances known as bacteriocins. Among the natural isolates of LAB from homemade cheeses, bacteriocin producers were found in both lactococci and lactobacilli. Lactococcus lactis subsp. lactis BGMN1-5 was found to produce three narrow spectrum class II heat-stable bacteriocins. In addition to bacteriocin production, BGMN1-5 synthesized a cell envelope-associated proteinase (CEP) and shows an aggregation phenotype. Another isolate, L. lactis subsp. lactis BGSM1-19 produces low molecular mass (7 kDa) bacteriocin SM19 that showed antimicrobial activity against Staphylococcus aureus, Micrococcus flavus and partially against Salmonella paratyphi. Production of bacteriocin reaches a plateau after 8 h of BGSM1-19 growth. Bacteriocin SM19 retained activity within the wide pH range from 1 to 12 and after the treatment at 100 degrees C for 15 min. Among collection of lactobacilli, the isolate Lactobacillus paracasei subsp. paracasei BGSJ2-8 produces heat-stable bacteriocin SJ (approx. 5 kDa) polypeptide. It retained activity after treatment for 1 h at 100 degrees C, and in the pH range from 2 to 11. In addition to isolates from cheeses, bacteriocin-producing human oral lactobacilli were detected. Most of them showed antimicrobial activity against streptococci, staphylococci and micrococci, but not against Candida. Isolate BGHO1 that showed the highest antimicrobial activity was determined as L. paracasei. Interestingly, Lactobacillus helveticus BGRA43, which was isolated from the human intestine showed strong activity against Clostridium sporogenes, but it was not possible to detect any bacteriocin production in this isolate by using standard procedures. Further analysis of antimicrobial activity revealed that BGRA43 has a relatively broad spectrum. Lactobacilli resistant to nisin were also detected among natural isolates. They produce bacteriocins, which have no activity against nisin producing lactococci.     

ISOLATION AND PARTIAL CHARACTERIZATION OF A NOVEL BACTERIOCIN PRODUCED BY LACTOCOCCUS LACTIS SSP. LACTIS MC38

This work presents the isolation and partial characterization of a new lactococcal bacteriocin produced by Lactococcus lactis ssp. lactis MC38. The bacteriocin demonstrated broad spectrum of inhibition activity against both pathogenic and food spoilage organisms, and various lactic acid bacteria. This antimicrobial substance appeared to be proteinaceous because its activity was completely inactivated by proteinase K and α‐chymotrypsin. It was heat and pH stable. The apparent molecular mass of the purified bacteriocin, determined by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, was 8.0 kDa. The amino acid composition of the studied bacteriocin was found to be quite different from known lactococcal bacteriocins. The calculation of the number of amino acid residues in the bacteriocin molecule revealed that it contained 62 amino acids.     

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.     

Probiotics and Its Functionally Valuable Products—A Review

During the past two decades probiotic bacteria have been increasingly proposed as health promoting bacteria in variety of food system, because of its safety, functional, and technological characteristics. Commonly, Lactobacillus spp., Bifidobacterium spp., Saccharomyces boulardii, and some other microorganisms have been considered as probiotic strains. Possibly these bacterial strains exerted several beneficial effects into gastrointestinal tract of host while administered with variety of food system. Lactic acid bacteria (LAB) usually produce antimicrobial substances like bacteriocin which have broad spectrum of antagonist effect against closely related Gram positive and Gram negative pathogens. LAB strains often produce polymeric substances such as exopolysaccharides (EPS) which increase the colonization of probiotic bacteria by cell–cell interactions in gastrointestinal tract. LAB also produces biosurfactant which showed that the wide range of antimicrobial activity against bacterial pathogen as well as its antiadhesive properties reduces the adhesion of pathogens into gastric wall membrane. Furthermore, LAB strains have also been reported for production of antioxidants which are ability to scavenge the free radicals such as superoxide anions and hydroxyl radicals. For this sense, this review article is mainly focused on the ecology, biosynthesis, genetics, target sites, and applications of bacteriocins and EPS from LAB strains. Moreover, this review discusses about the production and functions of nutritive essential element folate and iron chelating agent such as siderophores from LAB.     

Bacteriocins: safe, natural antimicrobials for food preservation.

Bacteriocins are antibacterial proteins produced by bacteria that kill or inhibit the growth of other bacteria. Many lactic acid bacteria (LAB) produce a high diversity of different bacteriocins. Though these bacteriocins are produced by LAB found in numerous fermented and non-fermented foods, nisin is currently the only bacteriocin widely used as a food preservative. Many bacteriocins have been characterized biochemically and genetically, and though there is a basic understanding of their structure-function, biosynthesis, and mode of action, many aspects of these compounds are still unknown. This article gives an overview of bacteriocin applications, and differentiates bacteriocins from antibiotics. A comparison of the synthesis. mode of action, resistance and safety of the two types of molecules is covered. Toxicity data exist for only a few bacteriocins, but research and their long-time intentional use strongly suggest that bacteriocins can be safely used.     

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.     

Preliminary characterization of bacteriocin-like substances from lactic acid bacteria isolated from organic leafy vegetables

This study presents the characterization of new strains of lactic acid bacteria (LAB) from organic vegetables. Forty-five strains of LAB isolated from vegetables were investigated by its antimicrobial activity against taxonomically related microorganisms. Genetic identification of selected LAB was performed by means of PCR method. These strains were Enterococcus faecium, Lactococcus lactis, Enterococcus hirae and Enterococcus canis. Bacteriocin-like substances were active against Gram-positive bacteria and Gram-negative foodborne pathogens (Listeria monocytogenes and Escherichia coli, respectively). The antimicrobial activity of LAB strains was inactivated by the addition of proteases, thus confirming the proteinaceous nature of the inhibition. In all four strains the bacteriocin activity was stable after extended refrigerated storage and freezing-thawing cycles. This fact suggests that bacteriocin produced by the four LAB strains may find application as biopreservatives in minimally processed vegetables.     

Combating biofilms of foodborne pathogens with bacteriocins by lactic acid bacteria in the food industry

Most foodborne pathogens have biofilm-forming capacity and prefer to grow in the form of biofilms. Presence of biofilms on food contact surfaces can lead to persistence of pathogens and the recurrent cross-contamination of food products, resulting in serious problems associated with food safety and economic losses. Resistance of biofilm cells to conventional sanitizers urges the development of natural alternatives to effectively inhibit biofilm formation and eradicate preformed biofilms. Lactic acid bacteria (LAB) produce bacteriocins which are ribosomally synthesized antimicrobial peptides, providing a great source of nature antimicrobials with the advantages of green and safe properties. Studies on biofilm control by newly identified bacteriocins are increasing, targeting primarily onListeria monocytogenes, Staphylococcus aureus, Salmonella, and Escherichia coli. This review systematically complies and assesses the antibiofilm property of LAB bacteriocins in controlling foodborne bacterial-biofilms on food contact surfaces. The bacteriocin-producing LAB genera/species, test method (inhibition and eradication), activity spectrum and surfaces are discussed, and the antibiofilm mechanisms are also argued. The findings indicate that bacteriocins can effectively inhibit biofilm formation in a dose-dependent manner, but are difficult to disrupt preformed biofilms. Synergistic combination with other antimicrobials, incorporation in nanoconjugates and implementation of bioengineering can help to strengthen their antibiofilm activity. This review provides an overview of the potential and application of LAB bacteriocins in combating bacterial biofilms in food processing environments, assisting in the development and widespread use of bacteriocin as a promising antibiofilm-agent in food industries.     

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.     

Potential of bacteriocinogenic Lactococcus lactis subsp. lactis inhabiting low pH vegetables to produce nisin variants

Antimicrobial behavior of lactic acid bacteria (LAB) has been explored since many years to assess their ability to produce bacteriocin, a natural preservative, to increase the shelf life of food. This study aims to characterize bacteriocin producing strains of lactic acid bacteria isolated from acidic to slightly acidic raw vegetables including tomato, bell pepper and green chili and to investigate their potential to inhibit food related bacteria. Among twenty nine LAB screened for antimicrobial activity, three exhibited antagonism against closely related bacterial isolates which was influenced by varying temperature and pH. They were identified up to strain level as Lactococcus lactis subsp. lactis TI-4, L. lactis subsp. lactis CE-2 and L. lactis subsp. lactis PI-2 based on 16S rRNA gene sequence. Their spectrum of inhibition was observed against food associated strains of Bacillus subtilis and Staphylococcus aureus. Moreover, L. lactis subsp. lactis PI-2 selected on the basis of higher antimicrobial activity was further evaluated for bacteriocin production which was detected as nisin A and nisin Z. These findings suggest the possible use of L. lactis strains of vegetable origin as protective cultures in slightly acidic as well as slightly alkaline food by the bio-preservative action of bacteriocins.     

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。     

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。     

Purification and partial characterization of antilisterial bacteriocin produced by Pediococcus pentosaceus KJBC11 from Idli batter fermented with Piper betle leaves

Bacteriocins are natural antimicrobial agents mainly act against closely related bacteria and at times unrelated organisms including various food spoilage and pathogenic organisms. Bacteriocins from Lactic Acid Bacteria (LAB) have been widely used for food preservation because of their safety nature. In this study, bacteriocin from Pediococcus pentosaceus KJBC11 was purified with the recovery of 15%, using cell adsorption‐desorption technique, gel permeation chromatography, hydrophobic interaction chromatography, and reversed phase HPLC successively. Molecular weight of bacteriocin KJBC11 was determined to be 4.5 kDa using Tricine SDS‐PAGE. The bacteriocin KJBC11 showed strong inhibitory activity against various Gram‐positive and Gram‐negative pathogens. Bacteriocin KJBC11 activity was not altered when treated with amylase, lipase, and trypsin but inactivated by protease and proteinase enzyme treatment. It was heat stable (100°C, 1 hr) and exhibited strong antimicrobial activity within the pH 3–7. Its mode of action was bactericidal in nature as revealed against Listeria monocytogenes showing leakage of internal contents out of the cell. Bacteriocin KJBC11 could belong to Class IIa‐pediocin like bacteriocins based on its characteristics as well as the presence of pediocin gene in the genome of the isolate KJBC11.

Practical applications

Studies on Lactic Acid Bacteria and bacteriocin have attracted increasing attention for a long time, due to their established role in food fermentation and preservation. The antimicrobial properties of bacteriocin became a trademark approach to achieve food safety and to counter the menace of antibiotic resistant pathogens. This study revealed a potent bacteriocin with wide range of antibacterial activity against various foodborne and clinically important pathogens to have potential application in food preservation and biomedicine.     

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。     

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.     

Comparative antimicrobial activity of enterocin L50, pediocin PA-1, nisin A and lactocin S against spoilage and foodborne pathogenic bacteria

The present work compares, under the same stated experimental conditions, the antimicrobial activity of crude and purified enterocin L50, pediocin PA-1, nisin A and lactocin S, produced by lactic acid bacteria (LAB) isolated from Spanish dry-fermented sausages. The bacteriocins were purified to homogeneity by ammonium sulphate precipitation, gel filtration (for lactocin S), and cation-exchange, hydrophobic-interaction, and reverse-phase-chromatography; high yields of pure bacteriocins were obtained. Minimal inhibitory concentration (MIC) of pure enterocin L50, pediocin PA-1, nisin A and lactocin S was determined against a broad spectrum of Gram-positive bacteria, including spoilage and foodborne pathogenic bacteria. The purified bacteriocins showed a broad antimicrobial spectrum similar to that exerted by crude bacteriocins. Enterocin L50 and pediocin PA-1 were very active againstListeria monocytogenes, which was quite resistant to nisin A and lactocin S. Enterocin L50 also displayed antimicrobial activity againstStaphylococcus aureus,Clostridium perfringensandClostridium botulinum. However, these pathogens were weakly inhibited, or not at all, by the other pure bacteriocins.