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Biofilm, a microbial community formed by especially pathogenic and spoilage bacterial species, is a critical problem in the food industries. It is an important cause of continued contamination by foodborne pathogenic bacteria. Therefore, removing biofilm is the key to solving the high pollution caused by foodborne pathogenic bacteria in the food industry. Lactobacillus, a commonly recognized probiotic that is healthy for consumer, have been proven useful for isolating the potential biofilm inhibitors. However, the addition of surface components and metabolites of Lactobacillus is not a current widely adopted biofilm control strategy at present. This review focuses on the effects and preliminary mechanism of action on biofilm inhibition of Lactobacillus-derived components including lipoteichoic acid, exopolysaccharides, bacteriocins, secreted protein, organic acids and some new identified molecules. Further, the review discusses several modern biofilm identification techniques and particularly interesting new technology of biofilm inhibition molecules. These molecules exhibit stronger inhibition of biofilm formation, playing a pivotal role in food preservation and storage. Overall, this review article discusses the application of biofilm inhibitors produced by Lactobacillus, which would greatly aid efforts to eradicate undesirable bacteria from environment in the food industries., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Lactic acid bacteria (LAB) are Gram-positive and catalase-negative microorganisms used to produce fermented foods. They appear morphologically as cocci or rods and they do not form spores. LAB used in food fermentation are from the Lactobacillus and Bifidobacterium genera and are useful in controlling spoilage and pathogenic microbes, due to the bacteriocins and acids that they produce. Consequently, LAB and their bacteriocins have emerged as viable alternatives to chemical food preservatives, curtesy of their qualified presumption of safety (QPS) status. There is growing interest regarding updated literature on the applications of LAB and their products in food safety, inhibition of the proliferation of food spoilage microbes and foodborne pathogens, and the mitigation of viral infections associated with food, as well as in the development of creative food packaging materials. Therefore, this review explores empirical studies, documenting applications and the extent to which LAB isolates and their bacteriocins have been used in the food industry against food spoilage microorganisms and foodborne pathogens including viruses; as well as to highlight the prospects of their numerous novel applications as components of hurdle technology to provide safe and quality food products.

Lactobacillus paragasseri was identified as a novel sister taxon of L. gasseri in 2018. Since the reclassification of L. paragasseri, there has been hardly any report describing the probiotic properties of this species. In this study, an L. paragasseri strain UBLG-36 was sequenced and analyzed to determine the molecular basis that may confer the bacteria with probiotic potential. UBLG-36 was previously documented as an L. gasseri strain. Average nucleotide identity and phylogenomic analysis allowed accurate taxonomic identification of UBLG-36 as an L. paragasseri strain. Analysis of the draft genome (~1.94 Mb) showed that UBLG-36 contains 5 contigs with an average G+C content of 34.85%. Genes essential for the biosynthesis of bacteriocins, adhesion to host epithelium, stress resistance, host immunomodulation, defense, and carbohydrate metabolism were identified in the genome. Interestingly, L. paragasseri UBLG-36 also harbored genes that code for enzymes involved in oxalate catabolism, such as formyl coenzyme A transferase (frc) and oxalyl coenzyme A decarboxylase (oxc). In vitro oxalate degradation assay showed that UBLG-36 is highly effective in degrading oxalate (averaging more than 45% degradation), a feature that has not been reported before. As a recently identified bacterium, there are limited genomic reports on L. paragasseri, and our draft genome sequence analysis is the first to describe and emphasize the probiotic potential and oxalate degrading ability of this species. With results supporting the probiotic functionalities and oxalate catabolism of UBLG-36, we propose that this strain is likely to have immense biotechnological applications upon appropriate characterization., Competing Interests: The authors have declared that no competing interests exist.

The human skin microbiota forms a key barrier against skin pathogens and is important in modulating immune responses. Recent studies identify lactobacilli as endogenous inhabitants of healthy skin, while inflammatory skin conditions are often associated with a disturbed skin microbiome. Consequently, lactobacilli-based probiotics are explored as a novel treatment of inflammatory skin conditions through their topical skin application. This review focuses on the potential beneficial role of lactobacilli (family Lactobacillaceae) in the skin habitat, where they can exert multifactorial local mechanisms of action against pathogens and inflammation. On one hand, lactobacilli have been shown to directly compete with skin pathogens through adhesion inhibition, production of antimicrobial metabolites, and by influencing pathogen metabolism. The competitive anti-pathogenic action of lactobacilli has already been described mechanistically for common different skin pathogens, such as Staphylococcus aureus, Cutibacterium acnes, and Candida albicans. On the other hand, lactobacilli also have an immunomodulatory capacity associated with a reduction in excessive skin inflammation. Their influence on the immune system is mediated by bacterial metabolites and cell wall-associated or excreted microbe-associated molecular patterns (MAMPs). In addition, lactobacilli can also enhance the skin barrier function, which is often disrupted as a result of infection or in inflammatory skin diseases. Some clinical trials have already translated these mechanistic insights into beneficial clinical outcomes, showing that topically applied lactobacilli can temporarily colonize the skin and promote skin health, but more and larger clinical trials are required to generate in vivo mechanistic insights and in-depth skin microbiome analysis., (© 2021 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

The study aimed to evaluate qualitatively and quantitatively the antimicrobial capacity of 10 potential probiotic Lactobacillus strains against model enteropathogens and spoilage microorganisms. The probiotic strains (live and heat-killed forms) were also assessed for their ability to inhibit adhesion of selected pathogens to Caco-2 cells. The largest inhibition zones (the diffusion method) were connected with the usage of whole bacteria cultures (WBC), also high and moderate with cell-free supernatant (CFS) and the lowest with cell-free neutralized supernatant (CNS). The highest antagonistic activity of Lactobacillus strains was observed against L. monocytogenes strains, moderate activity against Salmonella, Shigella, Escherichia coli, Pseudomonas and, the lowest against S.aureus, Bacillus and Enterococcus. The inhibition of adhesion to Caco-2 cells was very high in the case of E. coli, Salmonella and L. monocytogenes, and moderate in the case of S.aureus. On average, the inhibition effect was higher when pathogenic bacteria were treated by WBC, than heat-killed Lactobacillus. Although, in most samples, the effect was not significantly different (P> 0.05). The strains Lb. brevis O24 and Lb. rhamnosus K3 showed the biggest overall antimicrobial properties, and were most effective in adherence inhibition of investigated indicator strains. These bacteria or their metabolites can be used for the production of various foods or pharmaceutical products., (© The Author(s) 2021. Published by Oxford University Press on behalf of FEMS.)

Lactobacillus (L.) curvatus and L. sakei contain strains, which are assertive in sausage fermentation. Previous work has demonstrated differences in assertiveness at strain level within one species, and revealed either exclusion of competitors by complementary partner strains or their inhibition by single strains. This work addresses interspecies differences in the assertiveness of L. curvatus and L. sakei. Strain sets of L. curvatus and L. sakei were employed as starters in a fermented sausage model and their abundancy upon fermentation was determined by strain-specific MALDI-TOF MS identification. Generally, single or groups of L. sakei strains outcompeted L. curvatus strains. In multiple growth tests employing mMRS and mMSM it could be shown that assertive L. sakei strains can be predicted along their μ max in mMSM. Still, L. curvatus TMW 1.624 could suppress all L. curvatus and most L. sakei strains in competitive settings. This could be referred to its expression of several bacteriocins, which are active against all of the L. curvatus strains. Strain specific differences could be demonstrated in the susceptibility of L. sakei to bacteriocins, and in oxidative stress tolerance, which is higher in co-existing L. sakei strains than in the bacteriocin producer. This suggests that tolerance to bacteriocins and oxidative stress represent additional determinants for assertiveness, above previously reported bacteriocin production versus metabolic complementarism of partner strains., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Bacteriocins are functionally diverse toxins produced by most microbes and are potent antimicrobial peptides (AMPs) for bacterial ghosts as next generation vaccines. Here, we first report that the AMPs secreted from Lactobacillus taiwanensis effectively form ghosts of pathogenic bacteria and are identified as diverse bacteriocins, including novel ones. In detail, a cell-free supernatant from L. taiwanensis exhibited antimicrobial activities against pathogenic bacteria and was observed to effectively cause cellular lysis through pore formation in the bacterial membrane using scanning electron microscopy (SEM). The treatment of the cell-free supernatant with proteinase K or EDTA proved that the antimicrobial activity is mediated by AMPs, and the purification of AMPs using Sep-Pak columns indicated that the cell-free supernatant includes various amphipathic peptides responsible for the antimicrobial activity. Furthermore, the whole-genome sequencing of L. taiwanensis revealed that the strain has diverse bacteriocins, confirmed experimentally to function as AMPs, and among them are three novel bacteriocins, designated as Tan 1, Tan 2, and Tan 3. We also confirmed, using SEM, that Tan 2 effectively produces bacterial ghosts. Therefore, our data suggest that the bacteriocins from L. taiwanensis are potentially useful as a critical component for the preparation of bacterial ghosts.

The consumption of probiotics in the prevention and treatment of diarrhea have been clinically justified, comprehensive studied and explored in many products around the world. In Pakistan, recommendation of probiotic formulations is being emerged to control the increased mortality and morbidity from diarrhea under 5 years of age children. The objective of the study was to evaluate the antimicrobial potential of isolated Lactobacillus strains against diarrheagenic Escherichia coli. Twelve strains were isolated from different probiotic pharmaceutical formulations available in Pakistan. Physiological and biochemical characteristics of isolates were analyzed. Selective media was used for the growth of probiotic isolates and E. coli. Agar spot and well diffusion methods were employed to evaluate the antimicrobial activity of isolates and measured as a zone of inhibition (mm). Changes in cell morphology was observed by Scanning Electron Microscopy. Statistical analysis was adopted with a level of significance p<0.05. L. reuteri (28 mm) and L.plantarum (26 mm) showed significant inhibitory actions against E. coli due to increased organic acids and bacteriocins formations. Rest of isolates exhibited mild to moderate activity with an average inhibition (20 mm). L. sporogenes demonstrated weak antagonistic behavior. Use of multiple strains of Lactobacillus along with L. reuteri or L.plantarum as a therapeutic agent or in nutritional supplements could be a novel approach for the prevention and treatment of pediatric diarrhea.

Bacteriocins are defined as ribosomally synthesized antibacterial peptides/proteins that either kill or inhibit the growth of other bacteria. In the present study, the physicochemical properties, mode of action, and potential use in food preservation of a novel bacteriocin BM1122 from Lactobacillus crustorum MN047 were studied. It exhibited a broad inhibitory spectrum against selected Gram-positive and Gram-negative bacteria. Kinetic curves revealed efficient time-dependent bactericidal activity. Moreover, BM1122 possessed low hemolytic activity and good thermal stability between 60 and 120 °C. It was resistant to a wide range of pH (2 to 11) and proteinases. The scanning and transmission electron microscopy showed that BM1122 led to plasmolysis of Staphylococcus aureus and pore formation in Escherichia coli. Flow cytometric analysis demonstrated that BM1122 destroyed cell membrane integrity. Additionally, BM1122 could also inhibit biofilm formation and disturb the normal cell cycles of S. aureus and E. coli. Finally, BM1122 may enhance the inhibition of S. aureus and E. coli on beef meat stored at 4 °C for a duration of 10 days. These findings indicated that BM1122 had the potential for use as a natural preservative in the food industry. PRACTICAL APPLICATION: Fresh raw meats are highly perishable products. Bacteriocin BM1122 with a broad antibacterial spectrum can inhibit the growth of microorganisms in beef meat during refrigerated storage., (© 2020 Institute of Food Technologists®.)

Fresh meat harbors autochthonous microbiota with unknown risk potential, which is introduced in raw fermented sausages. Their growth can be limited by the use of safe, competitive starter strains. In the lack of time and cost-effective methods to track those starters at strain level, their assertiveness upon meat fermentation is widely unknown. Lactobacillus (L.) sakei and L. curvatus, which can be isolated from a variety of habitats, are frequently used as starter cultures. We monitored the assertiveness of 9 L. sakei and 9 L. curvatus strains in a model fermentation using MALDI-TOF-MS. An "in-house" MALDI-TOF-MS database with sub-proteome spectra of L. sakei and L. curvatus strains, as well as members of the autochthonous, spontaneously growing meat microbiota was established, validated and recognition rates were determined for each L. curvatus and L. sakei strain used. Competition studies were performed with standardized sausage batter, which was inoculated with a total of 10 6 cells of sets of 4-5 strains each of L. sakei and L. curvatus and 10 6 Staphylococcus carnosus ssp. carnosus cells. The pH and redox potential were monitored continuously. On days 0, 2 and 5 samples were taken to determine the CfU/g and a total of 96 isolates per sample were identified via MALDI-TOF-MS. MALDI-TOF-MS generally proved suitable for identification of isolates on strain level within the starter sets employed, but the recognition rate varied depending on the strain. Competition studies revealed dominance or co-dominance of strains within each set. However, their assertiveness significantly depended on the composition of the strain sets. Still, co-dominance or cooperation appeared effective to outgrow other members of the autochthonous meat microbiota, rather than dominance of single strains. For the latter, the ability to produce bacteriocins suggested itself for a crucial role in the assertiveness of starter strains., (Copyright © 2018 Elsevier B.V. All rights reserved.)

High Pressure Processing (HPP) and biopreservation can contribute to food safety by inactivation of bacterial contaminants. However these treatments are inefficient against bacterial endospores. Moreover, HPP can induce spore germination. The objective of this study was to select lactic acid bacteria strains to be used as bioprotective cultures, to control vegetative cells of spore-forming bacteria in ham after application of HPP. A collection of 63 strains of various origins was screened for their antagonistic activity against spore-forming Bacillus and Clostridium species and their ability to resist to HPP. Some safety requirements should also be considered prior to their introduction into the food chain. Hence, the selection steps included the assessment of biogenic amine production and antibiotic resistance. No strain produced histamine above the threshold detection level of 50 ppm. From the assessment of antibiotic resistance against nine antibiotics, 14 susceptible strains were kept. Antagonistic action of the 14 strains was then assessed by the well diffusion method against pathogenic or spoilage spore-forming species as Bacillus cereus, Clostridium sp. like botulinum, Clostridium frigidicarnis, and Clostridium algidicarnis. One Lactobacillus curvatus strain and one Lactococcus lactis strain were ultimately selected for their widest inhibitory spectrum and their potential production of bacteriocin. A Lactobacillus plantarum strain was included as control. Their resistance to HPP and ability to regrow during chilled storage was then assessed in model ham liquid medium. Treatments of pressure intensities of 400, 500, and 600 MPa, and durations of 1, 3, 6, and 10 min were applied. After treatment, cultures were incubated at 8 °C during 30 days. Inactivation curves were then fitted by using a reparameterized Weibull model whereas growth curves were modelled with a logistic model. Although the two Lactobacillus strains were more resistant than L. lactis to HPP, the latter was the only strain able to regrow following HPP. The absence of biogenic amine production of this strain after growth on diced cube cooked ham was also shown. In conclusion this L. lactis strain could be selected as representing the best candidate for a promising preservative treatment combining biopreservation and HPP to control spore-forming bacteria in cooked ham., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Lactobacillus curvatus 54M16 produced bacteriocins sak X, sak T α , sak T β and sak P. The aim of this study was to investigate the anti-listerial activity of the bacteriocins-producing strain against Listeria monocytogenes in vitro co-culture experiments and during the manufacture of fermented sausages. In MRS broth, Lb. curvatus 54M16 was able to inhibit L. monocytogenes to undetectable levels after 48 h at 20 °C or 5 days at 15 °C. Anti-listerial activity was lower during the production of fermented sausages with pathogen inoculation at levels of approximately 4 Log CFU g -1 . However, total inhibition of L. monocytogenes native to the raw ingredients was achieved over the course of the fermentation. Moreover, 16S rRNA-based analysis revealed the ability of Lb. curvatus 54M16 to dominate and affect the bacterial ecosystem, whereas spoilage-associated bacterial genera, such as Brochothrix, Psychrobacter, Pseudomonas and some Enterobacteriaceae, were found until the end of ripening in sausages without Lb. curvatus 54M16. The use of the bacteriocins-producing Lb. curvatus 54M16 in fermented sausages could be an important contribution to product safety, provided that eco-physiological factors and other preservation methods are maintained at levels required for the inhibition of pathogens in controlled conditions., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Escherichia coli is one of the main causes of uncomplicated urinary tract infections and responsible of vaginal infections. Lactobacilli can inhibit this pathogen by the production of antimicrobial substances as organic acids, hydrogen peroxide and/or bacteriocins. The aim of this work was to study the effects of beneficial vaginal lactobacilli on E. coli through in vitro experiments. The inhibitory activity of three vaginal Lactobacillus strains against E. coli was assessed using the agar plate diffusion. Moreover, the effect of Lactobacillus reuteri CRL (Centro de Referencia para Lactobacilos Culture Collection) 1324 on the adhesion and internalization capabilities of E. coli was studied on HeLa cells. Two Lactobacillus strains inhibited the growth of the pathogens by production of organic acids. L. reuteri CRL 1324 reduced the adhesion and internalization of E. coli 275 into HeLa cells. The results obtained suggest that L. reuteri CRL 1324 can be considered as a probiotic candidate for further in vivo studies for the prevention or treatment of urinary tract infections caused by E. coli.

Background: Lactobacillus gasseri is one of the dominant Lactobacillus species in the vaginal ecosystem. Some strains of this species have a high potential for being used as probiotics in order to maintain vaginal homeostasis, since they may confer colonization resistance against pathogens in the vagina by direct inhibition through production of antimicrobial compounds, as bacteriocins. In this work we have studied bacteriocin production of gassericin E (GasE), a novel bacteriocin produced by L. gasseri EV1461, a strain isolated from the vagina of a healthy woman, and whose production was shown to be promoted by the presence of certain specific bacteria in co-culture. Biochemical and genetic characterization of this novel bacteriocin are addressed., Results: We found that the inhibitory spectrum of L. gasseri EV1461 was broad, being directed to species both related and non-related to the producing strain. Interestingly, L. gasseri EV1461 inhibited the grown of pathogens usually associated with bacterial vaginosis (BV). The antimicrobial activity was due to the production of a novel bacteriocin, gassericin E (GasE). Production of this bacteriocin in broth medium only was achieved at high cell densities. At low cell densities, bacteriocin production ceased and only was restored after the addition of a supernatant from a previous bacteriocin-producing EV1461 culture (autoinduction), or through co-cultivation with several other Gram-positive strains (inducing bacteria). DNA sequence of the GasE locus revealed the presence of two putative operons which could be involved in biosynthesis and immunity of this bacteriocin (gaeAXI), and in regulation, transport and processing (gaePKRTC). The gaePKR encodes a putative three-component regulatory system, involving an autoinducer peptide (GaeP), a histidine protein kinase (GaeK) and a response regulator (GaeR), while the gaeTC encodes for an ABC transporter (GaeT) and their accessory protein (GaeC), involved in transport and processing of the bacteriocin. The gaeAXI, encodes for the bacteriocin gassericin E (GasE), a putative peptide bacteriocin (GaeX), and their immunity protein (GaeI)., Conclusions: The origin of the strain (vagina of healthy woman) and its ability to produce bacteriocins with inhibitory activity against vaginal pathogens may be an advantage for using L. gasseri EV1461 as a probiotic strain to fight and/or prevent bacterial infections as bacterial vaginosis (BV), since it could be better adapted to live and compete into the vaginal environment.

Lactic acid bacteria (LAB) are very important in converting of agricultural products into safe, delicious and shelf stable foods for human consumption. The preservative activity of LAB in foods is mainly attributed to the production of anti-microbial metabolites such as organic acids and bacteriocins which enables them to grow and control the growth of pathogens and spoilage microorganisms. Besides ensuring safety, bacteriocin-producing LAB with their probiotic potentials could also be emerging as a means to develop functional meat products with desirable health benefits. Nevertheless, to be qualified as a candidate probiotic culture, other prerequisite probiotic properties of bacteriocin-producing LAB have to be assessed according to regulatory guidelines for probiotics. Nham is an indigenous fermented sausage of Thailand that has gained popularity and acceptance among Thais. Since Nham is made from raw meat and is usually consumed without cooking, risks due to undesirable microorganisms such as Salmonella spp., Staphylococcus aureus, and Listeria monocytogenes, are frequently observed. With an ultimate goal to produce safer and healthier product, our research attempts on the development of a variety of new Nham products are discussed., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: Bacteriocins produced by lactic acid bacteria (LAB) attract considerable interest as natural and nontoxic food preservatives and as therapeutics whereas the bacteriocin-producing LAB are considered potential probiotics for food, human and veterinary applications, and in the animal production field. Within LAB the lactobacilli are increasingly used as starter cultures for food preservation and as probiotics. The lactobacilli are also natural inhabitants of the gastrointestinal (GI) tract and attractive vectors for delivery of therapeutic peptides and proteins, and for production of bioactive peptides. Research efforts for production of bacteriocins in heterologous hosts should be performed if the use of bacteriocins and the LAB bacteriocin-producers is ever to meet the high expectations deposited in these antimicrobial peptides. The recombinant production and functional expression of bacteriocins by lactobacilli would have an additive effect on their probiotic functionality., Results: The heterologous production of the bacteriocin enterocin A (EntA) was evaluated in different Lactobacillus spp. after fusion of the versatile Sec-dependent signal peptide (SP usp45 ) to mature EntA plus the EntA immunity gene (entA + entiA) (fragment UAI), and their cloning into plasmid vectors that permitted their inducible (pSIP409 and pSIP411) or constitutive (pMG36c) production. The amount, antimicrobial activity (AA) and specific antimicrobial activity (SAA) of the EntA produced by Lactobacillus sakei Lb790, Lb. plantarum NC8 and Lb. casei CECT475 transformed with the recombinant plasmids pSIP409UAI, pSIP411UAI and pMGUAI varied depending of the expression vector and the host strain. The Lb. casei CECT475 recombinant strains produced the largest amounts of EntA, with the highest AA and SAA. Supernatants from Lb. casei CECT (pSIP411UAI) showed a 4.9-fold higher production of EntA with a 22.8-fold higher AA and 4.7-fold higher SAA than those from Enterococcus faecium T136, the natural producer of EntA. Moreover, supernatants from Lb. casei CECT475 (pSIP411UAI) showed a 15.7- to 59.2-fold higher AA against Listeria spp. than those from E. faecium T136., Conclusion: Lb. casei CECT457 (pSIP411UAI) may be considered a promising recombinant host and cell factory for the production and functional expression of the antilisterial bacteriocin EntA.

Lactobacillus sakei subsp. sakei 2a is a bacteriocinogenic lactic acid bacterium isolated from Brazilian pork sausage, capable of inhibiting the growth of microbial pathogens, mainly Listeria monocytogenes. In order to optimize bacteriocin production for industrial applications, this study evaluated the effect of supplementation of MRS broth with glucose, Tween 20, Tween 80, sodium citrate, potassium chloride and cysteine, and effect of the initial pH and temperature of incubation of the medium on production of bacteriocins by L. sakei 2a. Adding glucose and Tween 20 to the medium, an initial pH of 5.0 or 5.5, and incubation temperatures of 25 °C or 30 °C resulted to the highest bacteriocin yields. Thus, a 2(4) factorial design with the four variables was performed, and statistical analysis showed that it was an adequate model (R (2) = 0.8296). In the studied range, the four parameters significantly influenced bacteriocin production, with the maximum yield produced at an initial pH between 5.5 and 7.0, a temperature between 25 and 30 °C and supplementation of the MRS broth with glucose from 3.25 to 6.0 g L(-1) and Tween 20 from 0.575 to 1.15% (v/v). Response Surface Methodology analysis indicated that the highest bacteriocin production (12800 AU mL(-1)) occurred in the MRS broth supplemented with 5.5 g L(-1) glucose and 1.05% Tween 20 at an initial pH of 6.28 and an incubation temperature of 25 °C. The amount of bacteriocin produced in commercial MRS broths under the same conditions was only 5600AU mL(-1).

Survival, bacteriocin(s) production, and antilisterial effect of Lactobacillus sakei subsp. sakei 2a were evaluated in a potentially synbiotic cheese spread, throughout storage at 4 °C and 15 °C for up to 28 days, using culture-dependent (plate count) and culture-independent (qPCR) methods. Bacteriocin(s) production in the food product was monitored by phenotypic and molecular (RT-qPCR) techniques. Three cheese spread trials (T) containing the prebiotic fiber inulin were produced in duplicates and studied: T1 (control - without inoculation of lactic acid bacteria); T2 (inoculated with the non-bacteriocinogenic Lb. sakei ATCC 15521 strain), and T3 (inoculated with the bacteriocinogenic Lb. sakei 2a strain). The cheese spreads were challenged with Listeria monocytogenes serotypes 4b and 1/2a, individually added to the food product. The counts of Lb. sakei 2a in the cheese spread T3 remained high during storage and the growth of L. monocytogenes was inhibited at both temperatures, especially L. monocytogenes 4b in the food product kept at 15 °C due to the production of bacteriocins (up to 6,400 AU/mL). Expression of the genes sakP and sakQ encoding for bacteriocins production during the cheese spread storage was demonstrated. Lb. sakei 2a can be used for production of potentially synbiotic cheese spreads with increased safety., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Bacteriocins are antimicrobial peptides which are ribosomally synthesized by mainly all bacterial species. LABs (lactic acid bacteria) are a diverse group of bacteria that include around 20 genera of various species. Though LABs have a tremendous potential for production of anti-microbial peptides, this group of bacteria is still underexplored for bacteriocins. To study the diversity among bacteriocin encoding clusters and the putative bacteriocin precursors, genome mining was performed on 20 different species of LAB not reported to be bacteriocin producers. The phylogenetic tree of gyrB, rpoB, and 16S rRNA were constructed using MEGA6 software to analyze the diversity among strains. Putative bacteriocins operons identified were found to be diverse and were further characterized on the basis of physiochemical properties and the secondary structure. The presence of at least two cysteine residues in most of the observed putative bacteriocins leads to disulphide bond formation and provide stability. Our data suggests that LABs are prolific source of low molecular weight non modified peptides., (Copyright © 2015. Published by Elsevier Ltd.)

Propionicin PLG-1 is a bacteriocin produced by Propionibacterium thoenii P127. Such bacteriocin inhibits wide range of food-borne pathogens such as pathogenic Escherichia coli, Pseudomonas aeruginosa, Vibrio parahaemolyticus, Yersinia enterocolitica and a strain of Corynebacterium sp. In the present study, plg-1 gene expressing propionicin PLG-1 was isolated, sequenced for the first time and the resulting sequence was analysed using several web-based bioinformatics programs. The PCR product containing plg-1 gene was transferred to different lactic acid bacterial (LAB) strains using pLEB590 as a cloning vector to give the modified vector pLEBPLG-1. LAB transformants showed an antimicrobial activity against Esch. coli DH5α (most affected strain), Listeria monocytogenes 18116, and Salmonella enterica 25566 as model pathogenic strains. Such LAB transformants can be used in dairy industry to control the food-borne pathogens that are largely distributed worldwide and to feed schoolchildren in the poor countries where dangerous epidemic diseases and diarrhoea prevail.

In the search of new antimicrobial agents against Neisseria gonorrhoeae, the bacteriocins-producing probiotic lactobacilli deserve special attention. The inhibitory effects of biosubstances such as organic acids, hydrogen peroxide and each bacteriocin-like inhibitory substance (BLIS) L23 and L60 on the growth of different gonococcal strains were investigated. Different non-treated and treated cell-free supernatants of two probiotic lactobacilli containing these metabolites were used. The aims of this work were (i) to evaluate the antimicrobial activity of the biosubstances produced by two probiotic lactobacilli, estimating the proportion in which each of them is responsible for the inhibitory effect, (ii) to define their minimum inhibitory concentrations (MICs) and, (iii) to determine the potential interactions between these biosubstances against N. gonorrhoeae. The main antimicrobial metabolites were the BLIS-es L23 and L60 in comparison with other biosubstances. Proportionally, their contributions to the inhibition on the gonococcal growth were 87.28% and 80.66%, respectively. The MIC values of bacteriocins were promising since these substances, when diluted, showed considerable inhibitory activity for all gonococci. In the interaction between bacteriocins, 100% of synergism was found on the gonococcal growth. In summary, this study indicates that both L23 and L60 could potentially serve to design new bioproducts against N. gonorrhoeae., (© FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The aims of this study were to isolate LAB with anti-Listeria activity from salami samples, characterize the bacteriocin/s produced by selected isolates, semi-purify them and evaluate their effectiveness for the control of Listeria monocytogenes during manufacturing of salami in a pilot scale. Two isolates (differentiated by RAPD-PCR) presented activity against 22 out of 23 L. monocytogenes strains for bacteriocin MBSa2, while the bacteriocin MBSa3 inhibited all 23 strains in addition to several other Gram-positive bacteria for both antimicrobials and were identified as Lactobacillus curvatus based on 16S rRNA sequencing. A three-step purification procedure indicated that both strains produced the same two active peptides (4457.9 Da and 4360.1 Da), homlogous to sakacins P and X, respectively. Addition of the semi-purified bacteriocins produced by Lb. curvatus MBSa2 to the batter for production of salami, experimentally contaminated with L. monocytogenes (10(4)-10(5) CFU/g), caused 2 log and 1.5 log reductions in the counts of the pathogen in the product after 10 and 20 days respectively, highlighting the interest for application of these bacteriocins to improve safety of salami during its manufacture., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Bacillus cereus is an endospore-forming, Gram-positive bacterium able to cause foodborne diseases. Lactic acid bacteria (LAB) are known for their ability to synthesize organic acids and bacteriocins, but the potential of these compounds against B. cereus has been scarcely documented in food models. The present study has examined the effect of the metabolites produced by Lactobacillus johnsonii CRL1647 and Enterococcus faecium SM21 on the viability of select B. cereus strains. Furthermore, the effect of E. faecium SM21 metabolites against B. cereus strains has also been investigated on a rice food model. L. johnsonii CRL1647 produced 128 mmol/L of lactic acid, 38 mmol/L of acetic acid and 0.3 mmol/L of phenyl-lactic acid. These organic acids reduced the number of vegetative cells and spores of the B. cereus strains tested. However, the antagonistic effect disappeared at pH 6.5. On the other hand, E. faecium SM21 produced only lactic and acetic acid (24.5 and 12.2 mmol/L, respectively) and was able to inhibit both vegetative cells and spores of the B. cereus strains, at a final fermentation pH of 5.0 and at pH 6.5. This would indicate the action of other metabolites, different from organic acids, present in the cell-free supernatant. On cooked rice grains, the E. faecium SM21 bacteriocin(s) were tested against two B. cereus strains. Both of them were significantly affected within the first 4 h of contact; whereas B. cereus BAC1 cells recovered after 24 h, the effect on B. cereus 1 remained up to the end of the assay. The LAB studied may thus be considered to define future strategies for biological control of B. cereus.

The human vagina is a complex and dynamic ecosystem containing an abundance of microorganisms. In women of childbearing age, this system is dominated by Lactobacillus spp. In the present work, seventeen newly isolated vaginal strains were identified by 16S rDNA sequencing and were investigated for their antimicrobial properties. Twelve of the isolated Lactobacillus strains showed activity against one or more microorganisms. Six and five of them produced substances that inhibited the growth of two different Klebsiella strains and Staphylococcus aureus, respectively. Two lactobacilli strains were active against an Escherichia coli strain, one isolate was active against an Enterococus faecalis strain and another lactobacilli strain showed antimicrobial activity against a Candida parapsilosis strain. The nature of the active compounds was additionally studied, and the presence of bacteriocin-like substances was proved. The genes related to the bacteriocin production in three of the newly isolated strains were identified and sequenced. The presence of gassericin A operon in the genome of the species Lactobacillus crispatus was described for the first time. The presence of antimicrobial activity contributes to their possible use as potential probiotic strains after further research.

Bacteriocin B231 produced by Lactobacillus pentosus, isolated from an artisanal raw cow's milk protected designation of origin Portuguese cheese, is a small protein with an apparent relative mass of about 5 kDa and active against a large number of Listeria monocytogenes wild-type strains, Listeria ivanovii and Listeria innocua. Bacteriocin B231 production is highly dependent on the type of the culture media used for growth of Lact. pentosus B231. Replacement of glucose with maltose yielded the highest bacteriocin production from eight different carbon sources. Similar results were recorded in the presence of combination of glucose and maltose or galactose. Production of bacteriocin B231 reached maximal levels of 800 AU/ml during the stationary phase of growth of Lact. pentosus B231 in MRS broth at 30 °C. Bacteriocin B231 (in cell-free supernatant) was sensitive to treatment with trypsin and proteinase K, but not affected by the thermal treatment in range of 55-121 °C, or freezing (-20 °C). Bacteriocin production and inhibitory spectrum were evaluated. Gene encoding plantaricin S has been detected in the genomic DNA. Virulence potential and safety of Lact. pentosus B231 were assessed by PCR targeted the genes gelE, hyl, asa1, esp, cylA, efaA, ace, vanA, vanB, hdc1, hdc2, tdc and odc. The Lact. pentosus B231 strains harbored plantaricin S gene, while the occurrence of virulence, antibiotic resistance and biogenic amine genes was limited to cytolysin, hyaluronidase, aggregation substance, adhesion of collagen protein, gelatinase, tyrosine decarboxylase and vancomycin B genes.

Lactic acid bacteria are non pathogenic organism widely distributed in nature typically involved in a large number of spontaneous food fermentation. The purpose of this study was to characterize the bacteriocinogenic lactobacilli from fermented idli batter which can find application in biopreservation and biomedicine. Eight most promising lactobacilli were chosen from twenty two isolates based on their spectrum of activity against other lactic acid bacteria and pathogens. The eight lactobacilli were characterized based on the various classical phenotypic tests, physiological tests and biochemical tests including various carbohydrate utilization profiles. All isolates were homo fermentative, catalase, and gelatin negative. Molecular characterization was performed by RAPD, 16S rRNA analysis, 16S ARDRA, and Multiplex PCR for species identification. RAPD was carried out using the primer R2 and M13. Five different clusters were obtained based on RAPD indicating strain level variation. 16S rRNA analysis showed 99 to 100% homology towards Lactobacillus plantarum. The restriction digestion pattern was similar for all the isolates with the restriction enzyme AluI. The subspecies were identified by performing Multiplex PCR using species specific primer. Among the five clusters, three clusters were clearly identified as Lactobacillus plantarum subsp. plantarum, Lactobacillus pentosus, and Lactobacillus plantarum subsp. argentoratensis.

Success in creating a synbiotic depends on compatibility between the chosen components--prebiotic and probiotic. In this work the interactions between Lactobacillus sp. strains isolated from yogurts and type strains of Lactobacillus sp. and Lactococcus sp., and the dependence of their growth and antibacterial activity on three oligosaccharides (OS)--palatinose, inulin and alpha-cyclodextrin were investigated. All isolated lactobacilli produce antibacterial compounds, which possibly are the bacteriocins of Lactobacillus casei ATCC334 strain. Results of growth analysis with different OS revealed that part of lactobacilli isolated from yogurts can effectively ferment inulin and may be used for the development of synbiotics. Palatinose and Lactobacillus acidophilus could be used as symbiotics with effective antibacterial activity. One of the types of Lactococcus sp. strains can assimilate palatinose and alpha-cyclodextrin, so they both can be used as components of synbiotics with the investigated lactococci. Results of this analysis suggest that the investigated isolated and type strains of Lactobacillus sp. and Lactoccocus sp. can be useful as probiotics in the development of synbiotics. Together with prebiotics--palatinose, inulin and alpha-cyclodextrin, the synbiotics, which could regulate not only the growth of beneficial bacteria in the gastrointestinal tract, but also their antibacterial activity, can be created.

The human gut represents a highly complex ecosystem, which is densely colonized by a myriad of microorganisms that influence the physiology, immune function and health status of the host. Among the many members of the human gut microbiota, there are microorganisms that have co-evolved with their host and that are believed to exert health-promoting or probiotic effects. Probiotic bacteria isolated from the gut and other environments are commercially exploited, and although there is a growing list of health benefits provided by the consumption of such probiotics, their precise mechanisms of action have essentially remained elusive. Genomics approaches have provided exciting new opportunities for the identification of probiotic effector molecules that elicit specific responses to influence the physiology and immune function of their human host. In this review, we describe the current understanding of the intriguing relationships that exist between the human gut and key members of the gut microbiota such as bifidobacteria and lactobacilli, discussed here as prototypical groups of probiotic microorganisms.

Antimicrobial wheat gluten film was obtained at pilot scale by Lactobacillus curvatus CRL705 bacteriocins inclusion in the film-forming solution. Bacteriocins' minimum inhibitory concentration for the film activation was 2133 AU cm(-3) (lactocin AL705) and 267 AU cm(-3) (lactocin 705). Mechanical and barrier properties as well as film ageing kinetics were not significantly affected by the addition of bacteriocins. The antimicrobial film performance during ageing was assessed. Film activity against Listeria innocua 7 and Lactobacillus plantarum CRL691 was observed over 50 days of ageing. Even when the release of bacteriocins from the film upon water contact was observed for both bacteriocins at the beginning of the ageing period, and anti-Listeria activity was delivered to the simulant up to the 15th day of ageing, film residual activity for both bacteriocins was observed over 50 days. The results confirm the potential of a gluten film doped with L. curvatus CRL705 bacteriocins as a carrier of bacteriocins to avoid Listeria and lactic acid bacterial growth, thus enhancing quality and safety in foods.

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., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

During the recent years extensive efforts have been made to find out bacteriocins from lactic acid bacteria (LAB) active against various food spoilage and pathogenic bacteria, and superior stabilities against heat treatments and pH variations. Bacteriocins isolated from LAB have been grouped into four classes. Circular bacteriocins which were earlier grouped among the four groups of bacteriocins, have recently been proposed to be classified into a different class, making it class V bacteriocins. Circular bacteriocins are special molecules, whose precursors must be post translationally modified to join the N to C termini with a head-to-tail peptide bond. Cyclization appears to make them less susceptible to proteolytic cleavage, high temperature and pH, and, therefore, provides enhanced stability as compared to linear bacteriocins. The advantages of circularization are also reflected by the fact that a significant number of macrocyclic natural products have found pharmaceutical applications. Circular bacteriocins were unknown two decades ago, and even to date, only a few circular bacteriocins from a diverse group of Gram positive organisms have been reported. The first example of a circular bacteriocin was enterocin AS-48, produced by Enterococcus faecalis AS-48. Gassereccin A, produced by Lactobacillus gasseri LA39, Reutericin 6 produced by Lactobacillus reuteri LA6 and Circularin A, produced by Clostridium beijerinickii ATCC 25,752, are further examples of this group of antimicrobial peptides. In the present scenario, Gassericin A can be an important tool in the food preservation owing to its properties of high pH and temperature tolerance and the fact that it is produced by LAB L. gasseri, whose many strains are proven probiotic.

Certain lactic acid bacteria (LAB) have the capacity to occupy mucosal niches of humans, including the oral cavity, gastrointestinal tract, and vagina. Among commensal, LAB are species of the acidophilus complex, which have proven to be a substantial reservoir for microorganisms with probiotic attributes. Specifically, Lactobacillus gasseri is an autochthonous microorganism which has been evaluated for probiotic activity based on the availability of genome sequence and species-specific adaptation to the human mucosa. Niche-related characteristics of L. gasseri contributing to indigenous colonization include tolerance of low pH environments, resistance to bile salts, and adhesion to the host epithelium. In humans, L. gasseri elicits various health benefits through its antimicrobial activity, bacteriocin production, and immunomodulation of the innate and adaptive systems. The genomic and empirical evidence supporting use of L. gasseri in probiotic applications is substantiated by clinical trial data displaying maintenance of vaginal homeostasis, mitigation of Helicobacter pylori infection, and amelioration of diarrhea., (© 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.)

Data on antimicrobial peptides (AMP) of lactobacilli, mechanism of their damagin effect, chemical nature and genetic control are presented. Regardless of the source of isolation AMP of lactobacilli except reuterin are peptides with low molecular weight (4 - 6 kDa), differ from each other by chemical structure, sensitivity to temperature, effect of various enzymes, active at neutral or more frequently low pH. Especially important are mechanisms ensuring fine regulation of phenotypic expression of bacteriocin synthesis and formation of immunity against their effect. Activity and most importantly the level of their production depend on the conditions in which these bacteria are present and are controlled by a three-component regulation system. This system includes signal peptide (pheromone), sensory histidine kinase, regulator protein activating transcription. Resistance of the producer to the effect of its own bacteriocin is ensured by the so called immunity protein. AMP of lactobacilli are able to influence septoformation, peptidoglycan and protein synthesis, affect cytoplasmic membranes causing their destabilization. Stages of this damaging effect are described: interaction of effector peptides with the membrane of the sensitive cell, positioning of the peptide in the region of connection with protein receptor, submerging into the core of the spiral structure membranes with the formation of a pore and exhaustion of ATP pool leading to cell death. Protection from AMP is determined by specific proteins blocking pore formation in the membrane by direct binding of damaging molecules or their receptors. Perspectives of further studies of the role of antimicrobial peptides of lactobacilli are discussed.

Lactic acid bacteria (LAB) produce a wide variety of antimicrobial peptides (bacteriocins) which contribute to the safety and preservation of fermented foods. This review discusses strategies that have been or could be employed to further enhance the commercial application of bacteriocins and/or bacteriocin-producing LAB for food use., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Bacteria play a significant role in water contamination. Chemicals are mostly used for the treatment of bacteriologically contaminated water. The use of bacterial interactions is a new approach to limit the pathogens' growth. Detection of antimicrobial substances produced by lactic acid bacteria against the waterborne pathogens is the objective of this work. Microbiological and biochemical methods were used to identify lactic acid bacteria having an antimicrobial activity. Evaluation of antimicrobial activity with growth kinetic measurements was performed. Four isolates of lactic acid bacteria obtained from whey and curd were identified. The predominant species belonging to the Lactobacillus genera are: Lactobacillus rhamnosus, Lactobacillus sakei, Lactobacillus paracasei, and Lactobacillus paraplantarum. The present study revealed that the Lactobacillus consortium is able to inhibit Staphylococcus aureus's growth along with Escherichia coli and Vibrio species. In mixed culture, after 24 h, the Lactobacillus consortium reduces the growth of S. aureus by 2.03 log; moreover, the growth of the latter bacteria totally ceased after 72 h of incubation. The protein produced by the Lactobacillus consortium was responsible for arresting the growth of S. aureus.

Strain SMXD51, isolated from chicken ceca and identified as Lactobacillus salivarius, produced a component that inhibits the growth of Gram-positive and Gram-negative bacteria and especially Campylobacter jejuni. The active peptide from the cell-free supernatant of Lb. salivarius SMXD51 was purified in three steps: (i) precipitation with 80% saturated ammonium sulfate, (ii) elution on a reversed phase SPE UPTI-CLEAN cartridge using different concentrations of acetonitrile, (iii) final purification by reversed phase HPLC on a C(18) column. The mode of action of this peptide of 5383.2 Da was identified as bactericidal, and its amino acid composition was established. This new bacteriocin SMXD51 appears potentially very useful to reduce Campylobacter in poultry prior to processing., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Fructo- (FOS) and galacto-oligosaccharides have been used to promote the growth of probiotics, mainly those from Lactobacillus genus. However, only few reports have evaluated the effect of prebiotics on bacteriocins activity and production. In this work, we characterized the effect of FOS supplementation on the growth, lactic and acetic acids production, and antimicrobial activity of crude extracts obtained from Lactobacillus strains isolated from ensiled corn and molasses. Seven out of 28 isolated Lactobacillus, belonging to Lactobacillus casei, Lactobacillus plantarum, and Lactobacillus brevis, showed antimicrobial activity against Listeria innocua. Among them, the strain L. plantarum LE5 showed antimicrobial activity against Listeria monocytogenes and Enteroccocus faecalis; while the L. plantarum LE27 strain showed antimicrobial effect against L. monocytogenes, E. faecalis, Escherichia coli and Salmonella enteritidis. This antimicrobial activity in most of the cases was obtained only after FOS supplementation. In summary, these results show the feasibility to increase the antimicrobial activity of Lactobacillus bacteriocins by supplementing the growth medium with FOS., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A strain of Lactobacillus paracasei subsp. paracasei BMK2005 isolated from healthy infant faeces has shown a remarkable antibacterial activity against 32 bacterial pathogenic strains of human clinical isolates. Among them, 13 strains belonging to species of Escherichia coli, Citrobacter freundii, Citrobacter diversus, Klebsiella oxytoca, Enterobacter cloacae and Pseudomonas aeruginosa were resistant to Cefotaxime (CTX) and Ceftazidime (CAZ), and 4 strains of Staphylococcus aureus were resistant to Methicillin (MRSA). This antibacterial activity was attributed to a bacteriocin designated as Paracaseicin A. It was heat-stable up to 120°C for 5 min and active within the pH range of 2-5. Its activity was lost when treated with proteases, which reveals its proteinaceous nature. This bacteriocin was successfully purified only by two steps of reversed phase chromatography. Its molecular mass, determined by mass spectrometry analysis, was 2,462.5 Da. To our knowledge, the present study is the first report on characterization and purification of a bacteriocin, produced by a L. paracasei subsp. paracasei strain exhibiting an antibacterial activity against various multidrug-resistant species of Gram-positive and Gram-negative bacteria, which reveals its potential for use in prevention or treatment of infections caused by multidrug-resistant species especially in cases of antibiotics-associated diarrhea (AAD).

The mechanisms by which intestinal bacteria achieve their associated health benefits can be complex and multifaceted. In this respect, the diverse microbial composition of the human gastrointestinal tract (GIT) provides an almost unlimited potential source of bioactive substances (pharmabiotics) which can directly or indirectly affect human health. Bacteriocins and fatty acids are just two examples of pharmabiotic substances which may contribute to probiotic functionality within the mammalian GIT. Bacteriocin production is believed to confer producing strains with a competitive advantage within complex microbial environments as a consequence of their associated antimicrobial activity. This has the potential to enable the establishment and prevalence of producing strains as well as directly inhibiting pathogens within the GIT. Consequently, these antimicrobial peptides and the associated intestinal producing strains may be exploited to beneficially influence microbial populations. Intestinal bacteria are also known to produce a diverse array of health-promoting fatty acids. Indeed, certain strains of intestinal bifidobacteria have been shown to produce conjugated linoleic acid (CLA), a fatty acid which has been associated with a variety of systemic health-promoting effects. Recently, the ability to modulate the fatty acid composition of the liver and adipose tissue of the host upon oral administration of CLA-producing bifidobacteria and lactobacilli was demonstrated in a murine model. Importantly, this implies a potential therapeutic role for probiotics in the treatment of certain metabolic and immunoinflammatory disorders. Such examples serve to highlight the potential contribution of pharmabiotic production to probiotic functionality in relation to human health maintenance., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Objectives: To evaluate the production of inhibitory substances against several urogenital pathogens and to determine the compatibility between selected vaginal lactobacilli to be considered as probiotic candidates., Study Design: The inhibitory activity of 38 vaginal Lactobacillus strains against urogenital pathogens was assessed using the agar plate diffusion., Method: The production of hydrogen peroxide was determined by the semi-qualitative tetramethyl-benzidine-peroxidase assay and that of lactic acid by high performance liquid chromatography. Pre-selected lactobacilli were genetically identified by ribosomal 16S-DNA sequencing and used to determine the compatibility of strains. Correlation values between some inhibitory properties were calculated., Results: 45% of the lactobacilli assayed inhibited the growth of various urogenital pathogens, except Candida albicans, mainly by the effect of organic acids. Even though 71% of the Lactobacillus strains produced hydrogen peroxide in the semi-qualitative test, the antimicrobial effect of the oxidative metabolite on pathogens was not detected under the experimental conditions assayed. On the other hand, the inhibition spectrum of salivaricin CRL 1328 was widened with respect to the one previously reported by our research team. With respect to the degree of interaction between the pre-selected lactobacilli, most of them showed inhibition of at least one strain, mainly due to the effects of both organic acids and hydrogen peroxide., Conclusion: Several lactobacilli that showed inhibitory activity against urogenital pathogens or produced hydrogen peroxide are compatible between them. Therefore, different potential combinations of strains are proposed for their inclusion in the design of probiotic products to be vaginally administered for the prevention of urogenital infections in women., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Near one hundred isolates of Lactobacillus paraplantarum, Lactobacillus pentosus and Lactobacillus plantarum from table olives were studied. Strains were genotyped by rep-PCR. Although the technique failed to differentiate some isolates at the species level, it proved a robust and easy procedure that could be useful for distinguishing between related strains of L. paraplantarum, L. pentosus and L. plantarum from a large pool of unrelated strains of these species. A PCR-based screening revealed the presence of the plantaricin encoding genes plnA, plnB, plnC, plnD, plnE/F, plnF, plnI, plnJ, plnK, plnG and plnN in most isolates of the three species. Sequences of bacteriocin genes present in L. paraplantarum and L. pentosus were homologous to L. plantarum genes. Through a discriminating analysis of the bacteriocin gene profiles, it was possible to establish a relationship between the origin of isolation and the LAB isolates, regardless of species., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Objective: Paracin 1.7 was a bacteriocin extracted from Lactobacillus paracasei HD1.7. In this study, we investigated quorum-sensing mechanism that regulates the metabolism of Paracin 1.7 in strain HD1.7., Methods: The antibacterial activity of strain HD1.7 under different growth conditions was analyzed using an agar-well diffusion method, and the cell density was controlled by adjusting nutrient levels in the culture medium., Results: The antibacterial activity of strain HD1.7 depended on cell density. Strain HD1.7 exhibited the antibacterial activity when the cell density reached a threshold (OD600 of 0.8 and cell dried weight of 0.3311 g/L). Addition of different concentrations of a signaling molecule in the supernatant of the fermentation broth affected the antibacterial activity. After removing the signal molecule, the antibacterial activity was significantly decreased., Conclusion: Paracin1.7 was the quorum-sensing signaling molecule in the HD1.7 fermentation broth and it could be auto-induced. The antibacterial activity of Paracin1.7 was regulated by the quorum-sensing system in HD1.7.

The purpose of the present study was to determine the inhibitory activities of two bacteriocins, produced by lactobacilli, against genital mycoplasmas. In this study, infections produced by genital mycoplasmas were studied; of these, 1.3% were caused by Mycoplasma hominis, 10.7% by Ureaplasma urealyticum and 5.6% by U. urealyticum + M. hominis. U. urealyticum was isolated from 75 out of 123 patients with genital mycoplasmas, while M. hominis was isolated from 9 patients (7.3%) and both U. urealyticum and M. hominis from 39 patients (31.7%). Bacteriocins, L23 and L60, produced by Lactobacillus fermentum and L. rhamnosus, respectively, appear to be two novel inhibitors of bacterial infection with potential antibacterial activity. Both bacteriocins proved to be active against 100% of strains tested; MICs of bacteriocin L23 ranged between 320 and 160 UA ml(-1) for 78% of the M. hominis strains and between 320 and 80 UA ml(-1) for 95% of the U. urealyticum strains. In addition, bacteriocin L60 was still active at 160 UA ml(-1) for a high percentage (56%) of M. hominis strains, and at 80 UA ml(-1) for 53% of the U. urealyticum strains. Interestingly, these antimicrobial substances produced by lactobacilli showed an inhibitory activity against genital mycoplasmas even when diluted. Altogether, our study indicates that the bacteriocins, L23 and L60, are good candidates for the treatment or prevention of genital infections in women.

The draft genome sequence of Lactobacillus salivarius GJ-24 isolated from the feces of healthy adults was determined. Its properties, including milk fermentation activity and bacteriocin production, suggest its potential uses as a probiotic lactic acid bacterium and start culture for dairy products., (Copyright © 2011, American Society for Microbiology. All Rights Reserved.)

Strain R1333, isolated from commercially available smoked salmon, was identified as Lactobacillus sakei based on biochemical tests, sugar fermentation reactions (API 50 CHL), PCR with species-specific primers and sequencing of the 16S rRNA gene. Strain R1333 produces a 3811 kDa class IIa bacteriocin, active against Streptococcus caprinus, Streptococcus macedonicus, Streptococcus spp., L. sakei, Lactococcus lactis subsp. lactis, Listeria innocua, Listeria ivanovii subsp. ivanovii and Listeria monocytogenes. The mode of activity against L. innocua 2030C and L. ivanovii subsp. ivanovii ATCC 19119 was bactericidal, resulting in cell lysis and enzyme- and DNA-leakage. The highest level of activity (1600 AU/mL) was recorded when cells were grown at 30°C in MRS broth (initial pH 6.5). Only 800 AU/mL was recorded when strain R1333 was grown in MRS without Tween 80. Lower levels of bacteriocin production were recorded when strain R1333 was grown in MRS at 20°C. Peptide R1333 adsorbs at low levels (200 AU/mL) to producer cells. Purification of bacteriocin R1333 was performed by 60% ammonium sulfate precipitation, followed by separation on a SepPak C(18) column and reverse-phase HPLC on a Nucleosil C(18) column with a linear gradient from 0.1% TFA to 90% acetonitryl. A molecular mass of 3811 kDa was determined by mass spectrometry. Based on mass spectrometry and sequencing of the PCR amplified fragment targeting the sakG gene, L. sakei R1333 is a potential producer of sakacin G. This is the first report of the identification of sakacin G produced by L. sakei isolated from smoked salmon., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

A new shuttle-cloning vector, pA13, was constructed and successfully introduced into Escherichia coli, Lactobacillus and Lactococcus strains. It showed high segregational and structural stability in all three hosts. The natural plasmid pSJ2-8 from L. paracasei subsp. paracasei BGSJ2-8 was cloned into pA13 using BamHI to obtain the construct, pB5. Sequencing and in silico analysis of pB5 revealed fifteen open reading frames (ORF). Plasmid pSJ2-8 harbours genes encoding the production of two bacteriocins, BacSJ and acidocin 8912. Combined N-terminal amino acid sequencing of BacSJ in combination with DNA sequencing of the bacSJ2-8 gene enabled determination of the primary structure of bacteriocin BacSJ. The bacSJ2-8 gene encodes 68-amino-acid peptide with a double-glycine leader peptide consisting of 18 amino acids, followed by the orf2 (bacSJ2-8i) which encodes the immunity protein of BacSJ. The production and functional expression of BacSJ in homologous and heterologous hosts suggest that bacSJ2-8 and bacSJ2-8i together with the genes encoding the ABC transporter and accessory protein are the minimal requirements for production of BacSJ. Biochemical and genetic analyses showed that BacSJ belongs to class II bacteriocins., (Copyright 2010 Elsevier B.V. All rights reserved.)

Lactobacilli have been shown to inhibit in vitro growth of many pathogens and have been used as probiotics to treat a broad range of gastrointestinal and/or vaginal disorders. We sought to determine the in vitro inhibitory potential of lactobacilli of vaginal origin to some bacteria associated with bacterial vaginosis (BV), to characterize the inhibitory substances produced by these lactobacilli and to assess H2O2 production. Vaginal specimens were obtained by swabbing the lateral vaginal walls from 107 women two months following BV treatment. One hundred and fifty eight Lactobacillus spp. were isolated in 82 of the 107 women. Lactobacillus jensenii was the predominant strain isolated among these women (29/158; 18.4%). Among 158 culture supernatants tested for antibacterial activity against BV-associated bacteria, none inhibited the growth of Bacteroides fragilis while 23% (37/158), 28% (45/158) and 29% (46/158) inhibited the growth of Prevotella bivia, Gardnerella vaginalis and Mobiluncus spp. respectively. The lactobacilli produced supernatants with a pH range between 2.62 and 6.71; the highly acidic (pH 2-3.99) supernatants were more inhibitory to the indicator strains. There was significant reduction in the mean zones of inhibition following chemical and physical treatment of the supernatants (p = 0.0025). Acid, bacteriocins and H2O2 demonstrated potential for antagonism of the bacterial pathogens. These substances may augment each other rather that each working independently on the pathogens., (2009 Elsevier Ltd. All rights reserved.)

The bacteriocins produced by Lactococcus lactis subsp. lactis C101910 (C101910) and NBRC 12007 (NBRC 12007) were used to prevent the growth of sake spoiling hiochi bacteria (Lactobacillus hilgardii, Lactobacillus fructivorans, and Lactobacillus paracasei) in namazake, which is raw (unpasteurized) sake. The bacteriocin concentrations required for decreasing the viable cell concentrations of L. hilgardii and L. fructivorans below the detection limit (1.0 x 10(2) cells/ml) in 24 h from the initial concentration of 4.0-9.5 x 10(5) cells/ml in the namazake at pH 4.5 and at 4 degrees C, were 18-35 U/ml and 5.6 U/ml for the bacteriocin from C101910 and NBRC 12007, respectively. To decrease the viable cell concentration of L. paracasei from the initial concentration of 7.5 x 10(5) cells/ml to below the detection limit (1.0 x 10(2) cells/ml) in 24 h, 350 U/ml bacteriocin from C101910 and 140 U/ml bacteriocin from NBRC 12007 were required. In experiments using McIlvaine buffer (pH 4.5) with 15% ethanol instead of namazake as the medium, the viable cell concentrations of L. hilgardii and L. paracasei decreased to less than 1.0 x 10(2) cells/ml, whereas those of L. fructivorans decreased to less than 1.0 x 10(3) cells/ml, when bacteriocins were added at the concentrations that had proven effective in namazake. The membrane depolarization assay using a fluorescent probe showed that the presence of ethanol stimulated the collapse of the membrane potential induced by bacteriocins. The ethanol induced collapse of the membrane potential suggests that the application of bacteriocins at the storage stage of namazake is more beneficial than when used in other stages of the sake brewing process., ((c) 2009 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.)

This review discusses methods of Helicobacter pylori (HP) eradication, causes and consequences of its steadily growing resistance to therapy recommended by Maastricht Consensus (2005) and alternative treatment schemes including "reserved" antibacterial preparations. Different approaches to the solution of this problem are recommended, such as the use of phenomenon of microbial antagonism between endosymbiotic microorgnisms (bifido- and lactobacteria) and opportunistic and pathogenic microflora, e.g. cytotoxic HP strains. The data are presented on the mechanisms of antimicrobial action of bifido- and lactobacteria, pathogenic activity of different HP cytotoxic strains, normal and pathological microbiocenosis of the stomach. Prospects for the use of antibiotics containing bifido- and lactobacteria for the treatment of HP-related conditions are discussed.

Although the physiological and nutritional properties of many probiotic strains are well understood, the study of their antiprotozoal potential is only at the beginning. This study describes the in vitro effect of four probiotic/bacteriocin-producing strains towards poultry Eimeria sp. oocysts. The oocyst reduction (P < 0.05) was detected from 4 h and/or 6 h of the cultivation in broth till the end of the experiment (32 h) without species or origin dependence. No differences in the reductive effect of bacteriocin-producing and non-producing strains were found. The character of substances with anticoccidial effect remains to be determined.