Production of antimicrobial substances by lactic acid bacteria I: determination of hydrogen peroxide

Overview of the Mechanistic Potential of Probiotics and Prebiotics in Cancer Chemoprevention

Despite of strides in modern cancer therapeutic strategies, there has not been a successful cure for it until now and prognostic side effects and substantial toxicity to chemotherapy and subsequent homeostatic imbalance remains a major concern for professionals in this field. The significance of the human microbiome in the pathogenesis of cancer is being recognized, documented, and established worldwide. Probiotics and prebiotics are some of the most extensively researched approaches to modulate the microbiota for therapeutic purposes, and research on their potential to prevent and treat cancer has sparked an immense amount of interest. The characteristics of probiotics and prebiotics allow for an array of efficient applications in cancer preventive measures. Probiotics can also be administered coupled with chemotherapy and surgery to alleviate their side effects and help promote the effectiveness of chemotherapeutic drugs. Besides showing promising results they are accompanied by potential risks and controversies that may eventually result in clinical repercussions. This review emphasizes the mechanistic potential and oncosuppressive effects of probiotic and prebiotics through maintenance of intestinal barrier function, modifying innate immune system, immunomodulation, intestinal microbiota metabolism, inhibition of host cell proliferation, preventing pathogen colonization, and exerting selective cytotoxicity against tumor cells.

In vitro, in vivo, and in silico analysis of synbiotics as preventive interventions for lipid metabolism in ethanol-induced adipose tissue injury

The risk of alcoholic liver disease (ALD) is increased by excessive ethanol drinking. For the prevention of ALD, the effects of ethanol on the liver, adipose tissue, and gut are crucial. Interestingly, garlic and a few probiotic strains can protect against ethanol-induced hepatotoxicity. However, the relationship between adipose tissue inflammation, Kyolic aged garlic extract (AGE), and Lactobacillus rhamnosus MTCC1423 in developing ALD is unknown. Therefore, the present study explored the effect of synbiotics (a combination of prebiotics and probiotics) on adipose tissue to prevent ALD. To investigate the efficacy of synbiotics administration on adipose tissue in preventing ALD, in vitro (3T3-L1 cells, N = 3) groups: control, control + LPS (lipopolysaccharide), ethanol, ethanol + LPS, ethanol + synbiotics, ethanol + synbiotics + LPS; in vivo (Wistar male rats, N = 6) groups: control, ethanol, pairfed, ethanol + synbiotics and in silico experiments were conducted. Lactobacillus multiplies in accordance with the growth curve when exposed to AGE. Additionally, Oil red O staining and scanning electron microscopy (SEM) demonstrated that synbiotics therapy maintained the morphology of adipocytes in the alcoholic model. In support of the morphological changes, quantitative real-time PCR demonstrated overexpression of adiponectin and downregulation of leptin, resistin, PPARγ, CYP2E1, iNOS, IL-6, and TNF-α after administration of synbiotics compared to the ethanol group. In addition, MDA estimation by high-performance liquid chromatography (HPLC) indicated that the synbiotics treatment reduced oxidative stress in rat adipose tissue. Consequently, the in-silico analysis revealed that AGE inhibited the C-D-T networks as PPARγ acting as the main target protein. The current study demonstrates that using synbiotics improves adipose tissue metabolism in ALD.

Role of Microbiota-Derived Metabolites in Alcoholic and Non-Alcoholic Fatty Liver Diseases

Chronic liver disease encompasses diseases that have various causes, such as alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD). Gut microbiota dysregulation plays a key role in the pathogenesis of ALD and NAFLD through the gut-liver axis. The gut microbiota consists of various microorganisms that play a role in maintaining the homeostasis of the host and release a wide number of metabolites, including short-chain fatty acids (SCFAs), peptides, and hormones, continually shaping the host's immunity and metabolism. The integrity of the intestinal mucosal and vascular barriers is crucial to protect liver cells from exposure to harmful metabolites and pathogen-associated molecular pattern molecules. Dysbiosis and increased intestinal permeability may allow the liver to be exposed to abundant harmful metabolites that promote liver inflammation and fibrosis. In this review, we introduce the metabolites and components derived from the gut microbiota and discuss their pathologic effect in the liver alongside recent advances in molecular-based therapeutics and novel mechanistic findings associated with the gut-liver axis in ALD and NAFLD.

Prospecting of potentially probiotic lactic acid bacteria from bovine mammary ecosystem: imminent partners from bacteriotherapy against bovine mastitis

Mastitis is one of the most important causes of loss of cattle production, burdening producers due to the increased cost of milk production and decreased herd productivity. The development of alternative methods for the treatment and prevention of mastitis other than traditional chemical antibiotic therapy needs to be implemented to meet international pressures to reduce the use of these drugs and promote the elimination of multiresistant microbial strains from the environment. Treatment with probiotic bacteria or yeast strains offers a possible strategy for the control of mastitis. The objective of this work was to isolate, identify, and characterize lactic bacteria from milk and the intramammary duct of Gyr, Guzerat, Girolando 1/2, and Holstein cattle breeds from Brazil. Samples of 115 cows were taken, a total of 192 bacteria isolates belonging to 30 species were obtained, and 81 were selected to evaluate their probiotic potential in in vitro characterization tests. In general, bacteria isolated from the mammary gland have low autoaggregation, cell surface hydrophobicity, and co-aggregation with mastitis etiological bacteria Staphylococcus aureus and Escherichia coli. Also, they have biofilm assembly capacity, inability to produce exopolysaccharides, high production of H₂O₂, and strong antagonism against mastitis pathogens. Ten lactic bacteria isolates were used in co-culture with human MDA-MB-231 breast epithelial cells to assess their adhesion capacity and impairment of the S. aureus invasion. Our results, therefore, contribute to the future production of new prevention and treatment tools for bovine mastitis.

Autochthonous Enterococcus durans PFMI565 and Lactococcus lactis subsp. lactis BGBU1-4 in Bio-Control of Listeria monocytogenes in Ultrafiltered Cheese

Nowadays, consumers are interested in cheese produced without chemical additives or high-temperature treatments, among which, protective lactic acid bacteria (LAB) cultures could play a major role. In this study, the aims were to isolate, identify and characterize antilisterial LAB from traditionally produced cheese, and utilize suitable LAB in cheese production. Among 200 isolated LAB colonies, isolate PFMI565, with the strongest antilisterial activity, was identified as Enterococcus durans. E. durans PFMI565 was sensitive to clinically important antibiotics (erytromicin, tetracycline, kanamycin, penicillin, vancomycin) and had low acidifying activity in milk. E. durans PFMI565 and the previously isolated bacteriocin producer, Lactococcus lactis subsp. lactis BGBU1–4, were tested for their capability to control Listeria monocytogenes in experimentally contaminated ultrafiltered (UF) cheeses during 35 days of storage at 4 °C. The greatest reductions of L. monocytogenes numbers were achieved in UF cheese made with L. lactis subsp. lactis BGBU1–4 or with the combination of L. lactis subsp. lactis BGBU1–4 and E. durans PFMI565. This study underlines the potential application of E. durans PFMI565 and L. lactis subsp. lactis BGBU1–4 in bio-control of L. monocytogenes in UF cheese.

In Vitro Evaluation of Probiotic Properties of Lactobacillus plantarum UBLP40 Isolated from Traditional Indigenous Fermented Food

In this study, traditional indigenous fermented food isolate Lactobacillus plantarum UBLP40 was screened for in vitro probiotic properties, antibiotic susceptibility, hemolytic activity, production of lactic acid, hydrogen peroxide, bile salt hydrolase and phytase, and antioxidative activity. Results showed that Lact. plantarum UBLP40 can survive simulated gastrointestinal conditions, adhere to mucin, possess a hydrophobic cell surface, ability to auto-aggregation, and possessed antimicrobial activity against Micrococcus luteus MTCC 106, methicillin-resistant Staphylococcus aureus subsp. aureus ATCC® BAA-1720, Pseudomonas aeruginosa MTCC 1688, and Escherichia coli MTCC 1687. Lact. plantarum UBLP40 produced 48.59 U/mg phytase and 1.78 ± 0.01 gm % lactic acid and showed the ability to produce hydrogen peroxide and bile salt hydrolase. Moreover, the usual antibiotic susceptible profile and non-hemolytic activity indicated the safety of the strain. The intracellular extract of UBLP40 showed 13.8 ± 1.4% (equivalent to ~8 µM butylated hydroxytoluene) α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging activity, reducing activity equivalent to 1 µg L-cysteine, Fe²⁺ chelation equivalent to 5 µM ethylenediaminetetraacetic acid, and exhibited 17.73 ± 4.40 µM glutathione per gram of protein. In conclusion, this study demonstrates that Lact. plantarum UBLP40 is a potential probiotic candidate.

Bacteriocinogenic Potential of Bacillus amyloliquefaciens Isolated from Kimchi, a Traditional Korean Fermented Cabbage

Bacteriocin production is considered a favorable property for various beneficial cultures. In addition to their potential as biopreservatives, bacteriocins are also promising alternatives for the control of multidrug-resistant pathogens and the inhibition of some viruses and cancer cells. The objective of this study was to screen and characterize a bacteriocin-producing strain with the aim of its future application for control of Listeria monocytogenes, an important food-borne pathogen. A total of 22 potentially bacteriocinogenic strains active against L. monocytogenes ATCC15313 were isolated from locally produced kimchi through a three-level approach. Pure cultures were obtained according to good microbiological practices and differentiated through RAPD-PCR using the primers OPL01, OPL09, and OPL11. Altogether, 5 strains were selected for further study. Specific focus was given to strain ST05DL based on its specific inhibitory activity against L. monocytogenes ATCC15313, while not affecting different strains belonging to the genera Lactobacillus, Pediococcus, Leuconostoc, and Weissella, most of which are beneficial microorganisms. The strain ST05DL was identified as Bacillus amyloliquefaciens based on its sugar fermentation profile obtained through API50CHB analysis and 16S rRNA partial sequencing. The antimicrobial compound produced by B. amyloliquefaciens ST05DL was found to be sensitive to pepsin and α-chymotrypsin, evidence of its proteinaceous nature. The presence of skim milk, NaCl, Tween 80, glycerol, and SDS did not affect the antimicrobial activity. The addition of 20% cell-free supernatant (CFS) obtained from a 24-h culture of B. amyloliquefaciens ST05DL to an exponentially growing culture of L. monocytogenes ATCC15313 successfully inhibited the test microorganisms during the monitored 10-h incubation. Optimal bacteriocin production by B. amyloliquefaciens ST05DL was observed during the stationary phase at 12 h (800 AU/mL) and remained stable for the next 15 h. The ratio between live and dead cells during this period was 74.37% and 25.66%, respectively, as determined by flow cytometry. The presence of the virulence genes hblA, hblB, hblC, nheA, nheB, and nheC was not detected in the total DNA of B. amyloliquefaciens ST05DL, and the strain was resistant only to ampicillin out of 10 tested antibiotics. Future evaluation of expressed bacteriocin/s by B. amyloliquefaciens ST05DL (amino acid sequence, molecular mass, cytotoxicity, detailed mode of action, etc.), will be the next step in the characterization and its potential application as biopreservative and/or pharmaceutical product.

The Role of Probiotics in Cancer Prevention

Simple Summary

Cancer is considered one of the leading causes of human mortality in the world and is the subject of much research. The risk of developing cancer depends on genetic factors, as well as the body’s immune status. The intestinal microbiome plays very important role in maintaining homeostasis in the human body. Probiotics have gained increasing medical significance due to the beneficial effect on the human body associated with the prevention and support of the treatment of many chronic diseases, including cancer in the absence of side effects. The aim of this review was to summarize the knowledge about the effect of probiotic microorganisms in the prevention of cancer. There is a lot of evidence that the use of probiotics can play an important role in cancer prevention and support anti-cancer therapies.

Abstract

The gut microbiome can play important role in maintaining homeostasis in the human body. An imbalance in the gut microbiome can lead to pro-inflammatory immune responses and the initiation of disease processes, including cancer. The research results prove some strains of probiotics by modulating intestinal microbiota and immune response can be used for cancer prevention or/and as adjuvant treatment during anticancer chemotherapy. This review presents the latest advances in research into the effectiveness of probiotics in the prevention and treatment support of cancer. The described issues concern to the anticancer activity of probiotic microorganisms and their metabolites. In addition, we described the potential mechanisms of probiotic chemoprevention and the advisability of using probiotics.

Evaluation of the fusion inhibitor P3 peptide as a potential microbicide to prevent HIV transmission in women

Microbicides are an important strategy for preventing the sexual transmission of HIV but, so far, the most advanced tenofovir-based microbicides have had modest efficacy. This has been related to adherence problems and high prevalence of tenofovir-resistant HIV-1 strains. P3 is a new peptide with potent activity against HIV that may be a good microbicide candidate. In this work P3 was formulated in a gel of hydroxyethyl cellulose and its activity, stability and safety profile in Balb/c mice were evaluated. HIV infection was fully blocked by a 1.5% gel containing P3 at the IC90 (366.4 nM) concentration. The antiviral activity did not change at 4°C during 4 months and at 25, 37 and 65°C for 1 week. P3 was stable and fully functional at acidic pH up to 24h, under different concentrations of hydrogen peroxide and in the presence of genital fluids up to 48h. P3 had no antibacterial activity and did not affect sperm motility and vitality. Finally, P3 didn't cause significant alterations in the vaginal epithelium of Balb/c mice at 0.06 (456.8 μM) and 0.2 mg/day (1522.7 μM) doses. These findings indicate that P3 is an excellent candidate for further development as a microbicide gel for the prevention of HIV transmission in women.

Microbiome, probiotics and neurodegenerative diseases: deciphering the gut brain axis

The gut microbiota is essential to health and has recently become a target for live bacterial cell biotherapies for various chronic diseases including metabolic syndrome, diabetes, obesity and neurodegenerative disease. Probiotic biotherapies are known to create a healthy gut environment by balancing bacterial populations and promoting their favorable metabolic action. The microbiota and its respective metabolites communicate to the host through a series of biochemical and functional links thereby affecting host homeostasis and health. In particular, the gastrointestinal tract communicates with the central nervous system through the gut-brain axis to support neuronal development and maintenance while gut dysbiosis manifests in neurological disease. There are three basic mechanisms that mediate the communication between the gut and the brain: direct neuronal communication, endocrine signaling mediators and the immune system. Together, these systems create a highly integrated molecular communication network that link systemic imbalances with the development of neurodegeneration including insulin regulation, fat metabolism, oxidative markers and immune signaling. Age is a common factor in the development of neurodegenerative disease and probiotics prevent many harmful effects of aging such as decreased neurotransmitter levels, chronic inflammation, oxidative stress and apoptosis-all factors that are proven aggravators of neurodegenerative disease. Indeed patients with Parkinson's and Alzheimer's diseases have a high rate of gastrointestinal comorbidities and it has be proposed by some the management of the gut microbiota may prevent or alleviate the symptoms of these chronic diseases.

Fighting Off Wound Pathogens in Horses with Honeybee Lactic Acid Bacteria

In the global perspective of antibiotic resistance, it is urgent to find potent topical antibiotics for the use in human and animal infection. Healing of equine wounds, particularly in the limbs, is difficult due to hydrostatic factors and exposure to environmental contaminants, which can lead to heavy bio-burden/biofilm formation and sometimes to infection. Therefore, antibiotics are often prescribed. Recent studies have shown that honeybee-specific lactic acid bacteria (LAB), involved in honey production, and inhibit human wound pathogens. The aim of this pilot study was to investigate the effects on the healing of hard-to-heal equine wounds after treatment with these LAB symbionts viable in a heather honey formulation. For this, we included ten horses with wound duration of >1 year, investigated the wound microbiota, and treated wounds with the novel honeybee LAB formulation. We identified the microbiota using MALDI-TOF mass spectrometry and DNA sequencing. In addition, the antimicrobial properties of the honeybee LAB formulation were tested against all wound isolates in vitro. Our results indicate a diverse wound microbiota including fifty-three bacterial species that showed 90 % colonization by at least one species of Staphylococcus. Treatment with the formulation promoted wound healing in all cases already after the first application and the wounds were either completely healed (n = 3) in less than 20 days or healing was in progress. Furthermore, the honeybee LAB formulation inhibited all pathogens when tested in vitro. Consequently, this new treatment option presents as a powerful candidate for the topical treatment of hard-to-heal wounds in horses.

A streptococcal NRAMP homologue is crucial for the survival of Streptococcus agalactiae under low pH conditions

Streptococcus agalactiae or Group B Streptococcus (GBS) is a commensal bacterium of the human gastrointestinal and urogenital tracts as well as a leading cause of neonatal sepsis, pneumonia and meningitis. Maternal vaginal carriage is the main source for GBS transmission and thus the most important risk factor for neonatal disease. Several studies in eukaryotes identified a group of proteins natural resistance-associated macrophage protein (NRAMP) that function as divalent cation transporters for Fe(2+) and Mn(2+) and confer on macrophages the ability to control replication of bacterial pathogens. Genome sequencing predicted potential NRAMP homologues in several prokaryotes. Here we describe for the first time, a pH-regulated NRAMP Mn(2+) /Fe(2+) transporter in GBS, designated MntH, which confers resistance to reactive oxygen species (ROS) and is crucial for bacterial growth and survival under low pH conditions. Our investigation implicates MntH as an important colonization determinant for GBS in the maternal vagina as it helps bacteria to adapt to the harsh acidic environment, facilitates bacterial adherence, contributes to the coexistence with the vaginal microbiota and plays a role in GBS intracellular survival inside macrophages.

Lactic acid bacterial symbionts in honeybees - an unknown key to honey's antimicrobial and therapeutic activities

Could honeybees' most valuable contribution to mankind besides pollination services be alternative tools against infections? Today, due to the emerging antibiotic-resistant pathogens, we are facing a new era of searching for alternative tools against infections. Natural products such as honey have been applied against human's infections for millennia without sufficient scientific evidence. A unique lactic acid bacterial (LAB) microbiota was discovered by us, which is in symbiosis with honeybees and present in large amounts in fresh honey across the world. This work investigates if the LAB symbionts are the source to the unknown factors contributing to honey's properties. Hence, we tested the LAB against severe wound pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and vancomycin-resistant Enterococcus (VRE) among others. We demonstrate a strong antimicrobial activity from each symbiont and a synergistic effect, which counteracted all the tested pathogens. The mechanisms of action are partly shown by elucidating the production of active compounds such as proteins, fatty acids, anaesthetics, organic acids, volatiles and hydrogen peroxide. We show that the symbionts produce a myriad of active compounds that remain in variable amounts in mature honey. Further studies are now required to investigate if these symbionts have a potential in clinical applications as alternative tools against topical human and animal infections.

Lactobacillus crispatus L1: high cell density cultivation and exopolysaccharide structure characterization to highlight potentially beneficial effects against vaginal pathogens

BACKGROUND

Vaginal lactic acid bacteria defend the host against pathogens through a combination of competitive exclusion, competition for nutrients, production of antimicrobial substances and through the activation of the immune system. A new human isolate named Lactobacillus crispatus L1 was characterized in this work, and a preliminary evaluation of its probiotic potential is described together with a process to obtain a high productivity of viable biomass.

RESULTS

In a simulated digestion process 1.8⋅10(10) cells∙ml(-1) survived the gastric environment with 80% viability, without being affected by small intestine juices. Experiments on six different C sources were performed to analyze growth and organic acids production and, glucose, provided the best performances. A microfiltration strategy was exploited to improve the cellular yield in 2 L-fermentation processes, reaching 27 g · l(-1) of dry biomass. Moreover, L. crispatus L1 demonstrated a greater stability to high concentrations of lactic acid, compared to other lactobacilli. The specific L. crispatus L1 exopolysaccharide was purified from the fermentation broth and characterized by NMR showing structural features and similarity to exopolysaccharides produced by pathogenic strains. Live L. crispatus L1 cells strongly reduced adhesion of a yeast pathogenic strain, Candida albicans in particular, in adherence assays. Interestingly a higher expression of the human defensin HBD-2 was also observed in vaginal cells treated with the purified exopolysaccharide, indicating a possible correlation with C. albicans growth inhibition.

CONCLUSIONS

The paper describes the evaluation of L. crispatus L1 as potential vaginal probiotic and the fermentation processes to obtain high concentrations of viable cells.

The oral mucosa immune environment and oral transmission of HIV/SIV

The global spread of human immunodeficiency virus (HIV) is dependent on the ability of this virus to efficiently cross from one host to the next by traversing a mucosal membrane. Unraveling how mucosal exposure of HIV results in systemic infection is critical for the development of effective therapeutic strategies. This review focuses on understanding the immune events associated with the oral route of transmission (via breastfeeding or sexual oral intercourse), which occurs across the oral and/or gastrointestinal mucosa. Studies in both humans and simian immunodeficiency virus (SIV) monkey models have identified viral changes and immune events associated with oral HIV/SIV exposure. This review covers our current knowledge of HIV oral transmission in both infants and adults, the use of SIV models in understanding early immune events, oral immune factors that modulate HIV/SIV susceptibility (including mucosal inflammation), and interventions that may impact oral HIV transmission rates. Understanding the factors that influence oral HIV transmission will provide the foundation for developing immune therapeutic and vaccine strategies that can protect both infants and adults from oral HIV transmission.

Role of Probiotics in health improvement, infection control and disease treatment and management

Research which concerns the usefulness of Probiotics show increasing interest based on the rise of their publications, products and the awareness of the public of their benefits. There is increasing interest concerning Probiotics from the public, researchers, governmental organizations (such as the WHO/FAO) and medicinal and food companies. Probiotics means "let good microbes work for you in different fields get their benefits and take a rest". Such work will include, food digestion, production of useful products to destroy the bad microbes, complement the functions of the missed digestive enzymes (due to missed or defective genes), and to maintain the digestive system's pH, and so on. Probiotics will augment the efficiency of our biological fermentors, the digestive system. Many authors have described the history and the progress of Probiotics and their different applications. In this review, we will focus mainly on three points, health improvement, infection control and disease management, which could be eliminated by the use of different types of direct uses of Probiotics or by the use of foods containing Probiotics.

The aetiology of bacterial vaginosis

Bacterial vaginosis (BV) is the most common vaginal infection among women of childbearing age. This condition is notorious for causing severe complications related to the reproductive health of women. Five decades of intense research established many risk factors for acquisition of BV; however, because of the complexity of BV and lack of a reliable animal model for this condition, its exact aetiology remains elusive. In this manuscript, we use a historical perspective to critically review the development of major theories on the aetiology of BV, ultimately implicating BV-related pathogens, healthy vaginal microbiota, bacteriophages and the immune response of the host. None of these theories on their own can reliably explain the epidemiological data. Instead, BV is caused by a complex interaction of multiple factors, which include the numerous components of the vaginal microbial ecosystem and their human host. Many of these factors are yet to be characterized because a clear understanding of their relative contribution to the aetiology of BV is pivotal to the formulation of an effective treatment for and prophylaxis of this condition.

A Simple Method for the Efficient Isolation of Genomic DNA from Lactobacilli Isolated from Traditional Indian Fermented Milk (dahi)

A simple, inexpensive and effective genomic DNA isolation procedure for Lactobacillus isolates from traditional Indian fermented milk (dahi) is described. A total of 269 Lactobacillus isolates from fermented milk collected from four places in North and west India were tested for lysis by an initial weakening of the Gram positive cell wall with Ampicillin followed by Lysozyme treatment. The average genomic DNA yield was ~50 μg/ml log phase culture. Quality and repeatability of the method was found to be adequate for subsequent molecular applications. The quality of the genomic DNA isolated by this method was verified by restriction digestion and polymerase chain reaction (PCR). No inhibition was observed in subsequent PCR amplification and restriction digestion. The presented method is rapid, cheap and useful for routine DNA isolation from gram positive bacteria such as Lactobacillus.

Characterization of the beneficial properties of lactobacilli isolated from bullfrog (Rana catesbeiana) hatchery

The present work addresses the isolation and partial identification of the microbial population of a R. catesbeiana hatchery in spring and summer as well as some beneficial properties of Lactobacillus strains isolated in different seasons and hatchery areas. The bacterial population was grouped into the following taxa: Lactobacillus spp., Pediococcus spp., Enterococcus faecalis and Ent. faecium, and Enterobacteriaceae (Enterobacter spp., Escherichia coli) while Pseudomonas aeruginosa and Staphylococcus epidermidis were isolated from frogs displaying red-leg syndrome. The Lactobacillus plantarum and L. curvatus strains isolated showed to inhibit the growth of red-leg syndrome associated pathogens and food-borne bacteria by organic acids. While L. plantarum CRL 1606 also inhibited red-leg syndrome related pathogens by hydrogen peroxide, meat spoilage bacteria were only inhibited by acidity. However, by using a MRS medium added with tetramethyl-benzidine and peroxidase, a high percentage of H(2)O(2)-producing lactobacilli were detected. The surface properties of Lactobacillus strains showed that a few strains were able to agglutinate ABO human erythrocytes, while the highest number of strains had a low to medium degree of hydrophobicity. This paper constitute the first study related to the beneficial properties of Lactobacillus isolated from a bullfrog hatchery, as well as the selection criteria applied to a group of strains, which could help to control or prevent bacterial infectious diseases in raniculture.

Advances in the design of probiotic products for the prevention of major diseases in dairy cattle

Probiotics are frequently used for multiple objectives and the majority of applications are performed both in human beings and in different animals. The specificity of species showed by the members of the indigenous microbiotia led us to isolate lactic acid bacteria (LAB) from their natural bovine ecosystems and to select those with probiotic potentiality. The beneficial probiotic LAB were isolated from the vaginal tract and mammary gland of adult heifers, faeces and oral cavity of newborn calves. Bacterial strains and their numbers varied in each tract under study. Their surface properties, evaluated using the MATH test, revealed that the higher number of low hydrophobic strains were isolated from vaginal tract, mammary gland or faeces. The capability of autoaggregation also differed with higher degree in those isolated from vagina, whereas those that originated in the mammary gland or faeces showed low autoaggregation characteristics. The production of antagonistic substances showed that the production of hydrogen peroxide was higher in the strains isolated from the vaginal tract, while those able to produce organic acid were isolated from all the environments. A few strains were able to produce bacteriocins and were isolated only from the mammary gland and faeces, but not from the vaginal tract. Further studies are being performed to complete the functional characterization of the strains in order to evaluate their survival in the environmental conditions of each tract. Finally, the selected strains could be combined for the design of probiotic products to be used both in adult cows and in neonates, based on the host-specificity, due to their autochthonous origin and their potential use in the tract where they were isolated.

Lactobacillus rhamnosus L60, a potential probiotic isolated from the human vagina

The vagina has been increasingly viewed as an "ecosystem" whose normal microflora help protect it from invading pathogens, including those that cause urinary tract infections and sexually transmitted diseases. We tested new strains of lactobacilli as potential probiotics for maintenance of urogenital tract health, as well as prevention and therapy of urogenital infections. A strain of lactobacilli isolated from the vagina of nonpregnant, healthy, premenopausal women was identified as Lactobacillus rhamnosus L60 by 16S rDNA sequence homology. L60 was evaluated for antimicrobial activity, in vitro antibiotic resistance, autoaggregation, surface hydrophobicity, co-aggregation with other bacterial species, hydrogen peroxide (H(2)O(2)) production, and bacterial adherence. It displayed a wide spectrum of antimicrobial activity against urogenital pathogens, and resistance to antibiotics commonly prescribed for infections caused by these pathogens. L60 produced H(2)O(2), adhered to vaginal epithelial cells, co-aggregated with Escherichia coli and Candida albicans, and displayed self-aggregation. In view of these characteristics, L60 is considered a potential probiotic, and will be further evaluated for preventive and therapeutic application locally in the vaginal tract.

Inhibition of Staphylococcus aureus by H2O2-producing Lactobacillus gasseri isolated from the vaginal tract of cattle

Infectious diseases are the major reproductive complication during postpartum. The bacteria that colonize the postpartum uterus of cattle are specific as well as opportunistic pathogens that include Staphylococcus aureus. The antibiotics and antiseptic agents used in the treatment of postpartum acute infections induce residues in foods, spread of bacterial resistance, increase in financial costs and failures in defense mechanisms of the host. Preventive treatment with probiotic products could decrease the use of antibiotics in dairy farming systems. Lactobacilli are present in the vaginal microflora of healthy cows. They can prevent pathogen colonization by mechanisms such as the production of antagonistic substances as lactic acid, H2O2, or bacteriocins. The aim of the present study was the selection of H2O2 generating lactobacilli from a group of 72 strains isolated from the vagina of cattle. Both Lactobacillus gasseri CRL1421 and Lactobacillus gasseri CRL1412, which share some probiotic properties, produce H2O2, detected by the plate colorimetric method. They were chosen to study the kinetics of H2O2 production under different culture conditions. Both microorganisms produced greater amounts of H2O2 in aerated than in static cultures. As L. gasseri CRL1421 had a greater capacity to generate H2O2, associative cultures with this strain and S. aureus were conducted. A significant decrease in the growth of the pathogen was detected after culture for 6h, this effect being greater under aerated conditions. The addition of catalase to mixed cultures partially abolished the inhibition, an effect that could be attributed to the combined action of H2O2 and other antagonistic metabolites. The simultaneous addition of catalase and NaOH to these cultures restored S. aureus growth. This observation suggests that the inhibition was produced by the combination of H2O2 and lactic acid, both released by the lactobacilli. Electron microphotographs showed the damage caused by the lactobacilli supernatant on the pathogenic cells. The treatment of S. aureus with lactic acid and hydrogen peroxide evidenced that each metabolite produced a different type of morphological damage. The number of viable cells obtained agrees with the electron microscopy observations. The results support the idea that L. gasseri CRL1421 could be successfully included in a probiotic product to prevent S. aureus infection in cows.