Metabolite Profiles of Lactic Acid Bacteria in Grass Silage

The metabolite production of lactic acid bacteria (LAB) on silage was investigated. The aim was to compare the production of antifungal metabolites in silage with the production in liquid cultures previously studied in our laboratory. The following metabolites were found to be present at elevated concentrations in silos inoculated with LAB strains: 3-hydroxydecanoic acid, 2-hydroxy-4-methylpentanoic acid, benzoic acid, catechol, hydrocinnamic acid, salicylic acid, 3-phenyllactic acid, 4-hydroxybenzoic acid, (trans, trans)-3,4-dihydroxycyclohexane-1-carboxylic acid, p-hydrocoumaric acid, vanillic acid, azelaic acid, hydroferulic acid, p-coumaric acid, hydrocaffeic acid, ferulic acid, and caffeic acid. Among these metabolites, the antifungal compounds 3-phenyllactic acid and 3-hydroxydecanoic acid were previously isolated in our laboratory from liquid cultures of the same LAB strains by bioassay-guided fractionation. It was concluded that other metabolites, e.g., p-hydrocoumaric acid, hydroferulic acid, and p-coumaric acid, were released from the grass by the added LAB strains. The antifungal activities of the identified metabolites in 100 mM lactic acid were investigated. The MICs against Pichia anomala, Penicillium roqueforti, and Aspergillus fumigatus were determined, and 3-hydroxydecanoic acid showed the lowest MIC (0.1 mg ml⁻¹ for two of the three test organisms).     

Growth and survival of lactic acid bacteria in lucerne silage

A rifampicin-resistant variant of two strains of Lactobacillus plantarum, one strain of Pediococcus acidilactici, and one strain of Enterococcus faecium were used for the experimental production of lucerne silage. Laboratory silage without inoculants served as a control. Counts of total anaerobes, total lactic acid bacteria (LAB), lactobacilli, pediococci, and enterococci were determined on days 14, 21, 30, 49, and 60 of lucerne fermentation. LAB dominated in silage microflora, reaching a percentage between 59 and 95 % of total anaerobes. Lactobacilli were found as a predominant group of LAB during the whole study. Lactobacilli reached numbers 8.74 log CFU/g in treated silage and 8.89 log CFU/g in the control at the first observation. Their counts decreased to 4.23 and 4.92 log CFU/g in treated silage and the control, respectively, on day 63 of fermentation. Similar decreases were observed in all bacterial groups. The treated silage samples possessed lower pH (4.2 vs. 4.5 in control samples) and contained more lactic acid compared to control silage. The identity of re-isolated rifampicin-resistant bacteria with those inoculated to the lucerne was evaluated by fingerprinting techniques. The fingerprint profiles of re-isolated bacteria corresponded to the profiles of strains used for the treatment. It could be concluded that supplemented LAB dominated in laboratory silage and overgrew naturally occurring LAB.     

Bacteriocins from lactic acid bacteria: production, purification, and food applications

In fermented foods, lactic acid bacteria (LAB) display numerous antimicrobial activities. This is mainly due to the production of organic acids, but also of other compounds, such as bacteriocins and antifungal peptides. Several bacteriocins with industrial potential have been purified and characterized. The kinetics of bacteriocin production by LAB in relation to process factors have been studied in detail through mathematical modeling and positive predictive microbiology. Application of bacteriocin-producing starter cultures in sourdough (to increase competitiveness), in fermented sausage (anti-listerial effect), and in cheese (anti-listerial and anti-clostridial effects), have been studied during in vitro laboratory fermentations as well as on pilot-scale level. The highly promising results of these studies underline the important role that functional, bacteriocinogenic LAB strains may play in the food industry as starter cultures, co-cultures, or bioprotective cultures, to improve food quality and safety. In addition, antimicrobial production by probiotic LAB might play a role during in vivo interactions occurring in the human gastrointestinal tract, hence contributing to gut health.     

Control of spoilage fungi by lactic acid bacteria

The evaluation of the potentiality of lactic acid bacteria (LAB) strains isolated from different origins to inhibit mould growth and to identify and characterize the antifungal metabolites were the aims of this study. From a total of ninety-one LAB strains tested, ten were selected due to their high inhibitory effect (>80%). The antifungal activity of the majority of the selected LAB strains was lost after the neutralization treatment determining the acidic nature of the antifungal metabolites. Lactic, acetic and phenyllactic (PLA) acids were identified as being responsible for antifungal effect in the 10 cell-free supernatants (CFS) evaluated. Amongst the strains evaluated, only Lactobacillus fermentum CRL 251 produced fungus inhibitory peptide/s, smaller than 10 kDa, thermostable, active in the pH range of 4–7 and sensitive to trypsin. This is the first report on antifungal peptide/s produced by a L. fermentum strain.     

Lactic acid bacteria diversity in corn silage produced in Minas Gerais (Brazil)

The diversity of lactic acid bacteria (LAB) in silages produced in warm climate countries is not well known. This study aimed to identify and characterise the metabolic and genotypic aspects of autochthonous LAB isolated from corn silage produced in the state of Minas Gerais, Brazil. Eighty-eight LAB were isolated. To evaluate their performance at the strain level, all isolates were distinguished among strains using random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) and repetitive extragenic palindromic PCR (REP-PCR) techniques. The organic acid and ethanol production were determined by high-performance liquid chromatography (HPLC). The fingerprints obtained by RAPD-PCR with a M13 primer were more discriminatory than those obtained with the REP-PCR technique using a (GACA)4 primer. Moreover, 28 representative isolates were identified as Lactobacillus acidophilus, L. buchneri, L. casei, L. diolivorans, L. hilgardii, L. paracasei, L. parafarraginis, L. plantarum, L. rhamnosus, L. zeae and Pediococcus acidilactici. Different fingerprinting profiles between isolates within the same species were observed. However, some strains isolated from different silages showed the same band profile, thus suggesting the presence of clusters with high similar fingerprints in silages from various regions. A variation in LAB diversity was observed in the silages of the evaluated regions, with L. rhamnosus and L. buchneri showing the highest distribution. Differences in organic acid production were observed among the strains belonging to the same species. This research contributes to a better understanding of the LAB community present in corn silage produced in warm climates. These strains will be studied as potential silage starters.     

Effect of NaCl-tolerant lactic acid bacteria and NaCl on the fermentation characteristics and aerobic stability of silage

NaCl-tolerant lactic acid bacteria (LAB) strains LC-10 ( Lactobacillus casei ) and LP-15 ( Lact. plantarum ) and NaCl were used as additives to sorghun ( Sorghum bicolor ). Numbers of LAB were significantly ( P < 0·05) higher in all the additive-treated silages than in the control silage at an early stage of ensiling. During the fermentation process, addition of NaCl or LAB effectively inhibited the growth of aerobic bacteria and clostridia, but not yeasts. All the additive-treated silages had significantly ( P < 0·05) lower pH, ammonia nitrogen content, dry matter loss and gas production but significantly ( P < 0·05) higher lactic acid content and residual water soluble carbohydrates compared with the control silage. The improvement in silage quality was in the order : LAB > NaCl > control. Yeast counts were high in all additive-based silages and they increased during the exposure of the silages to air. As a result, these silages suffered aerobic deterioration, whereas the control silage was stable. The results confirmed that the NaCl or LAB improved fermentation quality but did not prevent aerobic deterioration of the silage.     

Current approaches on the roles of lactic acid bacteria in crop silage

Lactic acid bacteria (LAB) play pivotal roles in the preservation and fermentation of forage crops in spontaneous or inoculated silages. Highlights of silage LAB over the past decades include the discovery of the roles of LAB in silage bacterial communities and metabolism and the exploration of functional properties. The present article reviews published literature on the effects of LAB on the succession, structure, and functions of silage microbial communities involved in fermentation. Furthermore, the utility of functional LAB in silage preparation including feruloyl esterase-producing LAB, antimicrobial LAB, lactic acid bacteria with high antioxidant potential, pesticide-degrading LAB, lactic acid bacteria producing 1,2-propanediol, and low-temperature-tolerant LAB have been described. Compared with conventional LAB, functional LAB produce different effects; specifically, they positively affect animal performance, health, and product quality, among others. In addition, the metabolic profiles of ensiled forages show that plentiful probiotic metabolites with but not limited to antimicrobial, antioxidant, aromatic, and anti-inflammatory properties are observed in silage. Collectively, the current knowledge on the roles of LAB in crop silage indicates there are great opportunities to develop silage not only as a fermented feed but also as a vehicle of delivery of probiotic substances for animal health and welfare in the future.     

Screening and selection of lactic acid bacteria strains suitable for ensiling grass

AIM: Lactic acid bacteria (LAB) strains shown to have broad-spectrum antimicrobial activity were screened for potential as grass silage inoculants. The strains capable of rapidly lowering the pH of the grass matrix and with low proteolytic activity were assessed in laboratory-scale silos in a grass matrix containing natural microbial flora. METHODS AND RESULTS: Screening of nine candidate strains was performed first in a grass extract medium. The four most promising strains were selected on the basis of growth rate in the medium, capacity to reduce pH and ability to limit the formation of ammonia-N. The efficiency of the selected strains was further assessed in a laboratory-scale ensiling experiment. Untreated (no additive) and formic acid served as controls. All tested inoculants improved silage quality compared with untreated. With one exception (Pediococcus parvulus E315) the fermentation losses in the inoculated silages were even lower than in the acid-treated control silage. Pure lactic acid fermentation was obtained in the timothy-meadow fescue silage with all inoculants. The results obtained in the ensiling experiments were consistent with those of the screening procedure, which appeared to predict correctly the potential of LAB as silage inoculants. The strains with a low ammonia production rate in the grass extract medium behaved similarly in the silage. Especially in this respect the strain Lactobacillus plantarum E76 was superior to the other candidates. CONCLUSIONS: The screening method using grass extract proved to be useful in strain selection. SIGNIFICANCE AND IMPACT OF THE STUDY: The rapid screening method developed for the LAB strains provides a useful tool for more systematic product development of commercial inoculant preparations. Time consuming and laborious ensiling experiments can be limited only to the most promising strains.     

Robusta coffee beans post-harvest microflora: Lactobacillus plantarum sp. as potential antagonist of Aspergillus carbonarius

Coffee contamination by ochratoxigenic fungi affects both coffee quality as well as coffee price with harmful consequences on the economy of the coffee exporting countries for whom which is their main source of income. Fungal strains were isolated from coffee beans and identified as black Aspergilli. Ochratoxigenic moulds like Aspergillus carbonarius were screened and selected for detailed studies. Also lactic acid bacteria (LAB) were isolated from silage coffee pulp and their antifungal activity was tested on dual-culture agar plate. Ten of the isolated LAB demonstrated antifungal effect against A. carbonarius. API 50 CH and APIZYM were used to perform phenotypic identification. 16S rDNA sequencing was made to confirm the results.     

New trends and opportunities in the development and use of inoculants for silage

Abstract: Inoculants are used as silage additives to improve preservation efficiency and to enhance animal performance. In most commercially available inoculants, homofermentative lactic acid bacteria (LAB) have been used because they are fast and efficient producers of lactic acid, improving natural silage fermentation. Specific LAB inuculants may also have beneficial effects on animal performance even if there is no effect on fermentation. However, these types of inoculants are not always advantageous. They do not necessarily prevent sermentation by clostridia in moist silages, and they sometimes impair the aerobic stability of grass and small grain silages. Therefore, new criteria for silage inoculants should be established which consider the specific needs of the crop being ensiled. New approaches which are being taken to develop improved inoculants for silage include the following: (1) using LAB isolates which are more specific to the target crops; (2) inclusion of heterofermentative LAB to produce volatile fatty acids to inhibit yeasts and moulds upon aerobic exposure; (3) inclusion of organisms other than LAB in inoculants to inhibit detrimental microorganisms; (4) selection or engineering of LAB strains to inhibit specific microorganisms; and (5) cloning and expression of genes which would enable selected LAB strains to utilize polysaccharides in crops which are low in soluble carbohydrates. Many of these new strategies for formulating inoculants are being tested, but further research is needed to determine the most successful approaches.     

Characterization,Identification and Application of Lactic Acid Bacteria Isolated from Forage Paddy Rice Silage

There has been growing interest to develop forage rice as a new feed resource for livestock. This study was to characterize the natural population of lactic acid bacteria (LAB) and select potentially excellent strains for paddy rice silage preparation in China. One hundred and twenty-six strains were isolated and screened from paddy rice silage prepared using a small-scale fermentation system, and ninety-nine of these isolates were considered to be LAB based on their Gram-positive and catalase-negative morphology and the production of most of their metabolic products as lactic acid. These isolates were divided into eight groups (A-H) on the basis of their morphological and biochemical characteristics. The Group A to H strains were identified as Lactobacillus (L.) plantarum subsp. plantarum (species ratio: 8.1%), L. casei (5.1%), Leuconostoc (Ln.) pseudomesenteroides (11.1%), Pediococcus (P.) pentosaceus (24.2%), Enterococcus (E.) mundtii (12.1%), Lactococcus (Lc.) garvieae (15.2%), E. faecium (9.1%) and Lc. lactis subsp. lactis (15.2%) based on sequence analyses of their 16S rRNA and recA genes. P. pentosaceus was the most abundant member of the LAB population in the paddy rice silage. A selected strain, namely L. casei R 465, was found to be able to grow under low pH conditions and to improve the silage quality with low pH and a relatively high content of lactic acid. This study demonstrated that forage paddy rice silage contains abundant LAB species and its silage can be well preserved by inoculation with LAB, and that strain R 465 can be a potentially excellent inoculant for paddy rice silage.     

Effects of <Emphasis Type="Italic">Lactobacillus buchneri</Emphasis> and <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> on fermentation,aerobic stability,bacteria diversity and ruminal degradability of alfalfa silage

Silages are important feedstuffs. Homofermentative lactic acid bacterial inoculants are often used to control silage fermentation. However, some research pointed out those homofermentative lactic acid bacteria (LAB) impaired the aerobic stability of wheat, sorghum, and corn silages. Adding heterofermentative LAB can produce more acetic acid, thereby stabilizing silages during aerobic exposure. Alfalfa is difficult to ensile. The present work was to study the effects of L. buchneri (heterofermentative LAB), alone or in combination with L. plantarum (homofermentative LAB) on the fermentation, aerobic stability, bacteria diversity and ruminal degradability of alfalfa silage. After 90 days ensiling, the pH, NH₃-N/TN, butyric acid content and molds counts of control were the highest. The inoculated silages had more lactic acid, acetic acid content and more lactic acid bacteria than the control. Inoculating LAB inhibited harmful microorganisms, such as Enterobacterium and Klebsiella pneumoniae. The L. buchneri + L. plantarum-inoculated silage had more acetic acid and less yeasts than other three treatments (P < 0.05), and lower NH₃-N/TN than control (P < 0.05). The CO₂ production of L. buchneri + L. plantarum-inoculated silage was less than that of L. plantarum-inoculated silage (P < 0.05). Inoculating LAB in alfalfa silages can decrease pH, increase the production of lactic and acetic acids, reduce the number of yeasts and molds, and inhibit Enterobacterium and K. pneumoniae. Inoculating with L. buchneri or L. buchneri + L. plantarum can improve aerobic stability of alfalfa silages. A combination of L. buchneri and L. plantarum is preferable because it enhanced alfalfa silage quality and aerobic stability.     

Potential of selected lactic acid bacteria to produce food compatible antifungal metabolites

The aim of this study was to assess the potential of lactic acid bacteria to inhibit the outgrowth of some common food-spoiling fungi. Culture supernatants of 17 lactic acid bacterial strains as well as of three commercial probiotic cultures were evaluated for antifungal activity using an agar-diffusion method. The method parameters were chosen in order to reveal compounds for potential use in food (bio)preservation. Thirteen strains showed antifungal activity of which five strains were very promising: Lactobacillus acidophilus LMG 9433, L. amylovorus DSM 20532, L. brevis LMG 6906, L. coryniformis subsp. coryniformis LMG 9196 and L. plantarum LMG 6907. Four of these five strains were further examined; it was found that the produced antifungal metabolites were pH-dependent. The exact chemical nature of these substances has not been revealed yet.     

苜蓿青贮用乳酸菌复合系Al2的组成多样性

苜蓿是高蛋白的饲料作物,青贮是保存青草过冬的主要手段,但苜蓿是难青贮的作物,添加乳酸菌制剂是解决苜蓿青贮难的有效措施。本研究室通过连续的限制性培养筛选到苜蓿青贮用乳酸菌复合系Al2,用变性梯度凝胶电泳(DGGE)、平板分离及建立16S rDNA克隆文库3种手段相结合分析Al2的组成多样性,确认Al2复合菌系由7株菌组成,全部属于Lactobacillus。其中3株菌Al2-1i,Al2-2i,Al2-3i通过平板分离得到,分别属于L.plantarum(99.9%)、L.kimchii(99.4%)、L.farciminis(100%)。在Al2复合菌系的16S rDNA克隆文库中,上述7种菌的组成比例分别为55.21%、19.79%、14.58%、3.13%、3.13%、3.13%、1.03%。     

Production of phenyllactic acid by lactic acid bacteria: an approach to the selection of strains contributing to food quality and preservation

The ability of lactic acid bacteria (LAB) to produce phenyllactic (PLA) and 4-hydroxy-phenyllactic (OH-PLA) acids, metabolites involved in food quality and preservation, has been evaluated by HPLC analysis in 29 LAB strains belonging to 12 species widely used in the production of fermented foods. Metabolite production was demonstrated for all strains of the species Lactobacillus plantarum, Lactobacillus alimentarius, Lactobacillus rhamnosus, Lactobacillus sanfranciscensis, Lactobacillus hilgardii, Leuconostoc citreum, and for some strains of Lactobacillus brevis, Lactobacillus acidophilus and Leuconostoc mesenteroides subsp. mesenteroides. Strains were distinguished by analysis of variance in three groups including 15 strains that produced both metabolites (0.16-0.46 mM PLA and 0.07-0.29 mM OH-PLA), five strains accumulating in culture only PLA (0.17-0.57 mM) and nine non-producer strains (< or = 0.10 mM PLA and < or = 0.02 mM OH-PLA). Improvement of phenyllactic acid production was obtained in a selected L. plantarum strain by increasing the concentration of phenylalanine in culture and using low amounts of tyrosine.     

青藏高原垂穗披碱草青贮饲料中乳酸菌的多样性及低温发酵菌株的筛选

【目的】探究青藏高原垂穗披碱草青贮饲料中乳酸菌的多样性,筛选在低温条件下(10、15和25°C)生长性能较好的优良菌株。【方法】将垂穗披碱草青贮饲料中分离纯化的乳酸菌进行形态特征观察及16S r RNA基因测序鉴定;用MRS液体培养基在10、15和25°C条件下分离、初筛乳酸菌,选取高吸光度值的菌株作为优势菌株。用绿汁发酵液在10、15和25°C条件下培养测定其p H值,选取低p H值菌株作为优势菌株,并综合MRS培养基筛选结果确定优良菌株。【结果】从不同温度和发酵阶段的垂穗披碱草青贮饲料中共分离得到108个乳酸菌菌株,它们分属于6个属、18个种。其中,清酒乳杆菌LS-24在15°C条件下发酵液p H值显著降低(P0.05),戊糖片球菌PP-63在发酵初期生长速度较快,植物乳杆菌LP-21在15°C条件下发酵液p H值降至3.9且有最大活菌数。【结论】在青藏高原垂穗披碱草青贮饲料中发现的乳酸菌属基本涵盖了前人在常温青贮饲料中发现的所有属,但种数略少;在108株菌中,清酒乳杆菌LS-24、戊糖片球菌PP-63和植物乳杆菌LP-21在低温条件下均表现出较好的繁殖和发酵特性,可作为青贮饲料低温发酵的备选菌株。     

Effects of ensilage on storage and enzymatic degradability of sugar beet pulp

Ensiling was investigated for the long-term storage of Sugar Beet Pulp (SBP). Eight strains of lactic acid bacteria (LAB) and a non-inoculated control were screened based on their ability to rapidly reduce pH, produce a large amount of lactic acid and inhibit undesirable fermentations. Lactobacillus brevis B-1836 (LAB #120), Lactobacillus fermentum NRRL B-4524 (LAB #137) and a non-inoculated control were selected for further research to determine the effects of LAB inoculation level and packing density on SBP silage quality and sugar yield upon enzymatic hydrolysis. Both SBP preservation and prevention of cellulose and hemicellulose loss were better when SBP was treated with LAB #137 compared to LAB #120 and the non-inoculated control. Additionally, the ensiling process was found to significantly improve the enzymatic digestibility of SBP by as much as 35%. The results suggest that ensiling may be a promising technology for SBP stabilization and pretreatment for bioconversion to products.     

Lactobacillus plantarum MiLAB 393 produces the antifungal cyclic dipeptides cyclo(L-Phe-L-Pro) and cyclo(L-Phe-trans-4-OH-L-Pro) and 3-phenyllactic acid

We have isolated a Lactobacillus plantarum strain (MiLAB 393) from grass silage that produces broad-spectrum antifungal compounds, active against food- and feed-borne filamentous fungi and yeasts in a dual-culture agar plate assay. Fusarium sporotrichioides and Aspergillus fumigatus were the most sensitive among the molds, and Kluyveromyces marxianus was the most sensitive yeast species. No inhibitory activity could be detected against the mold Penicillium roqueforti or the yeast Zygosaccharomyces bailii. An isolation procedure, employing a microtiter well spore germination bioassay, was devised to isolate active compounds from culture filtrate. Cell-free supernatant was fractionated on a C(18) SPE column, and the 95% aqueous acetonitrile fraction was further separated on a preparative HPLC C(18) column. Fractions active in the bioassay were then fractionated on a porous graphitic carbon column. The structures of the antifungal compounds cyclo(L-Phe-L-Pro), cyclo(L-Phe-trans-4-OH-L-Pro) and 3-phenyllactic acid (L/D isomer ratio, 9:1), were determined by nuclear magnetic resonance spectroscopy, mass spectrometry, and gas chromatography. MIC values against A. fumigatus and P. roqueforti were 20 mg ml(-1) for cyclo(L-Phe-L-Pro) and 7.5 mg ml(-1) for phenyllactic acid. Combinations of the antifungal compounds revealed weak synergistic effects. The production of the antifungal cyclic dipeptides cyclo(L-Phe-L-Pro) and cyclo(L-Phe-trans-4-OH-L-Pro) by lactic acid bacteria is reported here for the first time.     

Production of Propionibacterium shermanii biomass and vitamin B12 on spent media

AIMS: The propionibacteria are commercially important due to their use in the cheese industry, and there is a growing interest for their probiotic effects. Stimulatory effects of lactic acid bacteria (LAB) on propionic acid bacteria have been observed. This study was designed to examine the possibility of using spent media previously used to grow LAB for the production of biomass and metabolites of Propionibacterium freudenreichii subsp. shermanii. METHODS AND RESULTS: Seventeen MRS and vegetable juice media were prefermented by various LAB and evaluated for their ability to subsequently support the growth of Propionibacterium, using automated spectrophotometry (AS). Growth of Propionibacterium in spent media was strongly affected by the LAB strain used to produce the spent medium. The native MRS medium (not prefermented) yielded the highest optical density values followed by prefermented media by Lactobacillus acidophilus, Bifidobacterium longum and Lactococcus lactis. Prefermented cabbage juice enabled good growth of Propionibacterium. For the production of organic acids and vitamin B12, cells of Propionibacterium were concentrated and immobilized in alginate beads in the aim of accelerating the bioconversions. More propionic acid was obtained in spent media than in native MRS. The concentration of vitamin B12 was higher in media fermented with free cells than those with immobilized cultures; with the free cells, its concentration varied from 900 to 1800 ng ml(-1) of media. CONCLUSIONS: It was demonstrated that spent media could be recycled for the production of Propionibacterium and metabolites, depending on the LAB strain that was previously grown. Media remediation is needed to improve the production of vitamin B12, especially with immobilized cells. SIGNIFICANCE AND IMPACT OF THE STUDY: This study presents an option for recycling of spent media generated by producers of LAB or producers of fermented vegetables. The propionic fermentation may result in three commercial products: biomass, vitamin B12 or organic acids, which may be used as starters, supplements or food preservatives. It is an attractive process from economical and environmental standpoints.     

Antibacterial metabolites of lactic acid bacteria: their diversity and properties

The review is devoted to literature data on antimicrobial metabolites produced by lactic acid bacteria (LAB), which have long been used for the preparation of cultured dairy products. This paper summarizes data on low-molecular-weight antimicrobial substances, which are primary products or by-products of lactic fermentation. Individual sections are devoted to a variety of antifungal agents and bacteriocins produced by LAB; their potential use as food preservatives has been discussed. The characteristics and classification of bacteriocins are presented in a greater detail; their synthesis and mechanism of action are described using the example of nisin A, which belongs to class I lantibiotics synthesized by the bacterium Lactococcus lactis subsp. lactis. The mechanism of action of class II bacteriocins has been demonstrated with lacticin. Prospective directions for using LAB antimicrobial metabolites in industry and medicine are discussed in the Conclusion.