Taxonomic and strain-specific identification of the probiotic strain Lactobacillus rhamnosus 35 within the Lactobacillus casei group. Appl Environ Microbiol. 2008;74:2679-2689. [PMID: 18326671 DOI: 10.1128/aem.02286-07]

Investigating Safety and Technological Traits of a Leading Probiotic Species: Lacticaseibacillus paracasei

Lacticaseibacillus spp. are genetically close lactic acid bacteria species widely used in fermented products for their technological properties as well as their proven beneficial effects on human and animal health. This study, the first to include such a large collection of heterogeneous isolates (121) obtained from international collections belonging to Lacticaseibacillus paracasei, aimed to characterize the safety traits and technological properties of this important probiotic species, also making comparisons with other genetically related species, such as Lacticaseibacillus casei and Lacticaseibacillus zeae. These strains were isolated from a variety of heterogeneous sources, including dairy products, sourdoughs, wine, must, and human body excreta. After a preliminary molecular characterization using repetitive element palindromic PCR (Rep-PCR), Random Amplification of Polymorphic DNA (RAPD), and Sau-PCR, particular attention was paid to safety traits, evaluating antibiotic resistance profiles, biogenic amine (BA) production, the presence of genes related to the production of ethyl carbamate and diaminobenzidine (DAB), and multicopper oxidase activity (MCO). The technological characteristics of the strains, such as the capability to grow at different NaCl and ethanol concentrations and different pH values, were also investigated, as well as the production of bacteriocins. From the obtained results, it was observed that strains isolated from the same type of matrix often shared similar genetic characteristics. However, phenotypic traits were strain-specific. This underscored the vast potential of the different strains to be used for various purposes, from probiotics to bioprotective and starter cultures for food and feed production, highlighting the importance of conducting comprehensive evaluations to identify the most suitable strain for each purpose with the final aim of promoting human health.

Black Goji Berry (Lycium ruthenicum) Juice Fermented with Lactobacillus rhamnosus GG Enhances Inhibitory Activity against Dipeptidyl Peptidase-IV and Key Steps of Lipid Digestion and Absorption

With the global increase in hyperglycemia and hyperlipidemia, there is an urgent need to explore dietary interventions targeting the inhibition of dipeptidyl peptidase-IV (DPP-IV) and lipid digestion and absorption. This study investigated how Lactobacillus rhamnosus GG (LGG) affects various aspects of black goji berry (BGB) (Lycium ruthenicum Murr.) juice, including changes in physicochemical and functional properties, as well as microbiological and sensory attributes. Throughout the fermentation process with 2.5-10% (w/v) BGB, significantly improved probiotic viability, lactic acid production, and decreased sugar content. While total flavonoids increase, anthocyanins decrease, with no discernible change in antioxidant activities. Metabolite profiling reveals elevated phenolic compounds post-fermentation. Regarding the inhibition of lipid digestion and absorption, fermented BGB exhibits improved bile acid binding, and disrupted cholesterol micellization by approximately threefold compared to non-fermented BGB, while also increasing pancreatic lipase inhibitory activity. Furthermore, a decrease in cholesterol uptake was observed in Caco-2 cells treated with fermented BGB (0.5 mg/mL), with a maximum reduction of 16.94%. Fermented BGB also shows more potent DPP-IV inhibition. Sensory attributes are significantly improved in fermented BGB samples. These findings highlight the potential of BGB as a bioactive resource and a promising non-dairy carrier for LGG, enhancing its anti-hyperglycemic and anti-hyperlipidemic properties.

Elemental sulfur enhances the anti-fungal effect of Lacticaseibacillus rhamnosus Lcr35

Lacticaseibacillus rhamnosus Lcr35 is a well-known bacterial strain whose efficiency in preventing recurrent vulvovaginal candidiasis has been largely demonstrated in clinical trials. The presence of sodium thiosulfate (STS) has been shown to enhance its ability to inhibit the growth of Candida albicans strains. In this study, we confirmed that Lcr35 has a fungicidal effect not only on the planktonic form of C. albicans but also on other life forms such as hypha and biofilm. Transcriptomic analysis showed that the presence of C. albicans induced a metabolic adaptation of Lcr35 potentially associated with a competitive advantage over yeast cells. However, STS alone had no impact on the global gene expression of Lcr35, which is not in favor of the involvement of an enzymatic transformation of STS. Comparative HPLC and gas chromatography-mass spectrometry analysis of the organic phase from cell-free supernatant (CFS) fractions obtained from Lcr35 cultures performed in the presence and absence of STS identified elemental sulfur (S0) in the samples initially containing STS. In addition, the anti-Candida activity of CFS from STS-containing cultures was shown to be pH-dependent and occurred at acidic pH lower than 5. We next investigated the antifungal activity of lactic acid and acetic acid, the two main organic acids produced by lactobacilli. The two molecules affected the viability of C. albicans but only at pH 3.5 and in a dose-dependent manner, an antifungal effect that was enhanced in samples containing STS in which the thiosulfate was decomposed into S0. In conclusion, the use of STS as an excipient in the manufacturing process of Lcr35 exerted a dual action since the production of organic acids by Lcr35 facilitates the decomposition of thiosulfate into S0, thereby enhancing the bacteria's own anti-fungal effect.

Lacticaseibacillus rhamnosus CA15 (DSM 33960) as a Candidate Probiotic Strain for Human Health

Lactobacilli with probiotic properties have emerged as promising tools for both the prevention and treatment of vaginal dysbiosis. The present study aimed to study the in vitro probiotic potential of the Lacticaseibacillus rhamnosus CA15 (DSM 33960) strain isolated from a healthy vaginal ecosystem. The strain was evaluated for both functional (antagonistic activity against pathogens; H₂O₂, organic acid, and lactic acid production; antioxidant and anti-inflammatory activities; ability to adhere to intestinal mucus and to both CaCo-2 and VK7/E6E7 cell lines; exopolysaccharide production; surface properties; and ability to survive during gastrointestinal transit) and safety (hemolytic, DNase, and gelatinase activities; mucin degradation ability; production of biogenic amines; and resistance to antimicrobials) characteristics. Data revealed that the tested strain was able to antagonize a broad spectrum of vaginal pathogens. In addition, the adhesion capacity to both vaginal and intestinal cell lines, as well as anti-inflammatory and antioxidant activities, was detected. The ability of the Lacticaseibacillus rhamnosus CA15 (DSM 33960) strain to survive under harsh environmental conditions occurring during the gastrointestinal passage suggests its possible oral delivery. Thus, in vitro data highlighted interesting probiotic properties of the CA15 (DSM 33960) strain, which could represent a valuable candidate for in vivo vaginal infections treatment.

Evaluation of the Probiotic In Vitro Potential of Lactic Acid-Producing Bacteria from Canine Vagina: Possible Role in Vaginal Health

Simple Summary

The use of microorganisms with probiotic capacity, obtained from the natural microbiota itself, is an alternative tool for the treatment and prevention of some animal pathologies. In this study, a total of 94 bitches were sampled in order to identify the lactic acid-producing microbiota of the vagina. Following the general isolation of the vaginal microbiota, 100 strains of lactic acid-producing bacteria (LAB) were identified. Through Gram staining and basic biochemical tests (catalase, oxidase and haemolysis), 13 LAB strains with possible probiotic capacity were selected to undergo an evaluation of resistance to gastrointestinal conditions (pH, lysozyme, bile salts and hydrogen peroxide) and safety and efficacy in vitro (resistance to antibiotics and antimicrobial capacity by disk diffusion). After the selection, only 3 of 100 strains showed in vitro probiotic potential.

Abstract

Lactic acid-producing bacteria (LAB) are being widely studied due to their probiotic potential. The aim of the present study was to determine and identify the presence of LAB from canine vaginal samples, as well as to evaluate their probiotic in vitro potential. Ninety-four bitches were included in the study. Vaginal samples were obtained by means of a sterile swab and streaked on Man Rogosa Sharpe agar plates. A total of 100 LAB strains were obtained and submitted to Gram stains and basic biochemical tests, which included catalase, oxidase and haemolysis tests. Thirteen strains belonging to the genera Lactobacillus (n = 10), Lactococcus (n = 2) and Pediococcus (n = 1) were selected as potential probiotics and further subjected to evaluation of resistance to gastrointestinal conditions (pH, lysozyme, bile salts and hydrogen peroxide) and safety and efficacy in vitro (resistance to antibiotics and antimicrobial capacity). Only three strains, one Lactobacillus lactis and two Lactobacillus plantarum, accomplished the requirements for being considered as potential in vitro probiotics.

Probiotics: Should All Patients Take Them?

The usefulness of probiotics in the treatment as well as prevention of many infections and disorders has been confirmed by previous clinical studies. They can protect not only against gastrointestinal diseases such as diarrhea or enteritis but they have proven efficacy against pneumonia, urogenital infection, depression/anxiety, cancer metastasis, obesity, and others. However, it should be mentioned that not all clinical trials have shown improvement of health in patients undergoing probiotic treatment, and very rarely have even reported that probiotic strains may be the causative agents of opportunistic infections. Studies have documented cases of sepsis/bacteremia, endocarditis, liver abscess, pneumonia, and fungemia caused by probiotic strains, mainly in high-risk groups. This review summarizes the cases of infections caused by probiotic strains and the potential hazard associated with the supplementation of probiotics in seriously ill and hospitalized patients.

Perspectives from the Society for Pediatric Research: Probiotic use in urinary tract infections, atopic dermatitis, and antibiotic-associated diarrhea: an overview

Probiotics have received significant attention within both the scientific and lay communities for their potential health-promoting properties, including the treatment or prevention of various conditions in children. In this article, we review the published data on use of specific probiotic strains for three common pediatric conditions: the prevention of urinary tract infections and antibiotic-associated diarrhea and the treatment of atopic dermatitis. Research into the utility of specific probiotic strains is of varying quality, and data are often derived from small studies and case series. We discuss the scientific merit of these studies, their overall findings regarding the utility of probiotics for these indications, issues in reporting of methods, and results from these clinical trials, as well as future areas of investigation.

Identification of sulfur components enhancing the anti-Candida effect of Lactobacillus rhamnosus Lcr35

GYNOPHILUS (Lcr REGENERANS) is a live biotherapeutic product (LBP) aimed at restoring the vaginal microbiome and contains the live biotherapeutic microorganism Lactobacillus rhamnosus Lcr35. In this study, the LBP formulation and manufacturing process significantly enhanced the anti-Candida activity of L. rhamnosus Lcr35, with a complete loss of viability of the yeast after 48 h of coincubation. Sodium thiosulfate (STS), one excipient of the product, was used as a potentiator of the anti-Candida spp. activity of Lactobacilli. This contact-independent phenomenon induced fungal cell disturbances, as observed by electron microscopy observations. Nonverbal sensory experiments showed clear odor dissimilarities between cocultures of L. rhamnosus Lcr35 and C. albicans in the presence and absence of STS, suggesting an impact of odor-active metabolites. A volatolomic approach allowed the identification of six odor-active compounds, including one sulfur compound that was identified as S-methyl thioacetate (MTA). MTA was associated with the antifungal effect of Lcr35, and its functional link was established in vitro. We show for the first time that the LBP GYNOPHILUS, which is a highly active product in the reduction of vulvovaginal candidiasis, requires the presence of a sulfur compound to fully achieve its antifungal effect.

Probiotic Cocktail Identified by Microbial Network Analysis Inhibits Growth, Virulence Gene Expression, and Host Cell Colonization of Vancomycin-Resistant Enterococci

The prevalence of vancomycin resistant enterococcus (VRE) carrier-state has been increasing in patients of intensive care unit and it would be a public health threat. Different research groups conducted decolonizing VRE with probiotic and the results were controversial. Therefore, a systemic approach to search for the probiotic species capable of decolonizing VRE is necessary. Thus, VRE was co-cultured with ten probiotic species. The fluctuations of each bacterial population were analyzed by 16S rRNA sequencing. Microbial network analysis (MNA) was exploited to identify the most critical species in inhibiting the VRE population. The MNA-selected probiotic cocktail was then validated for its efficacy in inhibiting VRE, decolonizing VRE from Caco-2 cells via three approaches: exclusion, competition, and displacement. Finally, the expression of VRE virulence genes after co-incubation with the probiotic cocktail were analyzed with quantitative real-time PCR (qRT-PCR). The MNA-selected probiotic cocktail includes Bacillus coagulans, Lactobacillus rhamnosus GG, Lactobacillus reuteri, and Lactobacillus acidophilus. This probiotic combination significantly reduces the population of co-cultured VRE and prevents VRE from binding to Caco-2 cells by down-regulating several host-adhesion genes of VRE. Our results suggested the potential of this four-strain probiotic cocktail in clinical application for the decolonization of VRE in human gut.

Screening and Identification of New Types of Exopolysaccharides-Producing Lactic Acid in the Inner Mongolia Dairy Products

Exopolysaccharides (EPS) is a type of polysaccharide produced by lactic acid bacteria (LAB) that can be directly used in foods to make the products more excellent. Therefore, batch studies were performed to explore the effect of different LAB on the production of EPS and antioxidant activity. Five strains with high EPS yield and antioxidant activity were screened out from 66 strains isolated from Tibetan dairy products. The results show that EPS produntion of the five strains (B55, B62, B30, 7830 and K2) were 110.66, 145.48, 132.78, 122.11 and 111.72 mg·L−1, respectively, and they have a higher DPPH free radical scavenging activity (56.29, 66.43, 62.94, 68.71, 61.87%). Five LAB strains were identified and classified based on screening, purification and 16S rDNA sequences. Molecular characterization based on partial sequence 16S rDNA homology confirmed the initial identification as Lactobacillus fermentum (B55, B62), Lactobacillus plantarum (7830), Pediococcus acidilactici (B30) and Lactobacillus helveticus (K2).

Lactobacillus rhamnosus Lcr35 as an effective treatment for preventing Candida albicans infection in the invertebrate model Caenorhabditis elegans: First mechanistic insights

The increased recurrence of Candida albicans infections is associated with greater resistance to antifungal drugs. This involves the establishment of alternative therapeutic protocols, such as probiotic microorganisms whose antifungal potential has already been demonstrated using preclinical models (cell cultures, laboratory animals). Understanding the mechanisms of action of probiotic microorganisms has become a strategic need for the development of new therapeutics for humans. In this study, we investigated the prophylactic anti-C. albicans properties of Lactobacillus rhamnosus Lcr35® using the in vitro Caco-2 cell model and the in vivo Caenorhabditis elegans model. In Caco-2 cells, we showed that the strain Lcr35® significantly inhibited the growth (~2 log CFU.mL-1) and adhesion (150 to 6,300 times less) of the pathogen. Moreover, in addition to having a pro-longevity activity in the nematode (+42.9%, p = 3.56.10-6), Lcr35® protects the animal from the fungal infection (+267% of survival, p < 2.10-16) even if the yeast is still detectable in its intestine. At the mechanistic level, we noticed the repression of genes of the p38 MAPK signalling pathway and genes involved in the antifungal response induced by Lcr35®, suggesting that the pathogen no longer appears to be detected by the worm immune system. However, the DAF-16/FOXO transcription factor, implicated in the longevity and antipathogenic response of C. elegans, is activated by Lcr35®. These results suggest that the probiotic strain acts by stimulating its host via DAF-16 but also by suppressing the virulence of the pathogen.

Critical insights into antibiotic resistance transferability in probiotic Lactobacillus

Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, with respect to metabolism, immune function, and nutrition. Any perturbation of these beneficial microbes leads to gut dysbiosis, which triggers the development of various disorders in the gastrointestinal system. Probiotics play a key role in resolving the dysbiosis posed by external factors such as antibiotics, other substances, or interventions. Supplementing probiotics with antibiotics is favorable in reducing the harmful effects of antibiotics on gut flora. These microbes also possess specific intrinsic drug resistance mechanisms that aid their survival in the internal environment. According to US Food and Drug Administration reports, species belonging to Lactobacillus and Bifidobacterium genera are the most common probiotics consumed by humans through commercial products. However, various studies have reported the tendency of microbes to acquire specific drug resistance, in recent years, through various mechanisms. The reports on transferable resistance among probiotics are of major concern, of which minimal information is available to date. The aim of this review was to describe the pros and cons of drug resistance among these beneficial microorganisms with emphasis on the recommended selection criteria for specific probiotics, devoid of transferable drug resistance genes, suitable for human consumption.

Comparative phase I randomized open-label pilot clinical trial of Gynophilus® (Lcr regenerans®) immediate release capsules versus slow release muco-adhesive tablets

Gynophilus^® (Lcr regenerans^®) is a live biotherapeutic product (LBP) that contains the live biotherapeutic microorganism Lactobacillus rhamnosus Lcr35^®, which is indicated to restore vaginal health. The aim of the study was to compare the safety, ease of use, and compliance of two formulations (immediate release: IR capsule and slow release: SR muco-adhesive tablets) as well as the colonization of Lcr35^® in healthy women. This phase I study (Comprigel) is a parallel, randomized, 4-arm, and open-label clinical trial evaluating an IR daily capsule formulation vs. a SR tablet administered every 3, 4, or 5 days for 21 days. Self-collected vaginal swabs were used to quantify Lcr35^® and characterize the composition and structure of the vaginal microbiota. Both LBPs were well-tolerated, and no severe adverse effects were reported. All groups had Lcr35^® vaginal concentrations over 10⁷ colony forming unit per milliliter of vaginal secretion on each day in the study. The new Gynophilus^® slow release tablets administered either every 3, 4, or 5 days provided vaginal concentrations that were not significantly different from those of classic Gynophilus^® (capsule) once-a-day regimen. The LBPs and the different regimens did not adversely influence the abundance of native Lactobacillus spp. and indeed tended to favor their growth and reduce colonization by non-Lactobacillus spp. This study illustrates that the SR muco-adhesive LBP tablet (Gynophilus^® SR) administered every 3 or 4 days as a safe, well-tolerated, and efficacious alternative to a more demanding IR daily capsule and could protect women's healthy vaginal microbiome by promoting endogenous Lactobacillus spp.

Monitoring Viable Cells of the Biological Control Agent Lactobacillus plantarum PM411 in Aerial Plant Surfaces by Means of a Strain-Specific Viability Quantitative PCR Method

A viability quantitative PCR (v-qPCR) assay was developed for the unambiguous detection and quantification of Lactobacillus plantarum PM411 viable cells in aerial plant surfaces. A 972-bp region of a PM411 predicted prophage with mosaic architecture enabled the identification of a PM411 strain-specific molecular marker. Three primer sets with different amplicon lengths (92, 188, and 317 bp) and one TaqMan probe were designed. All the qPCR assays showed good linearity over a 4-log range and good efficiencies but differed in sensitivity. The nucleic acid-binding dye PEMAX was used to selectively detect and enumerate viable bacteria by v-qPCR. The primer set amplifying a 188-bp DNA fragment was selected as the most suitable for v-qPCR. The performance of the method was assessed on apple blossoms, pear, strawberry, and kiwifruit leaves in potted plants under controlled environmental conditions, as well as pear and apple blossoms under field conditions, by comparing v-qPCR population estimations to those obtained by qPCR and specific plate counting on de Man-Rogosa-Sharpe (MRS)-rifampin. The population estimation did not differ significantly between methods when conditions were conducive to bacterial survival. However, under stressful conditions, differences between methods were observed due to cell death or viable-but-nonculturable state induction. While qPCR overestimated the population level, plate counting underestimated this value in comparison to v-qPCR. PM411 attained stable population levels of viable cells on the flower environment under high relative humidity. However, the unfavorable conditions on the leaf surface and the relatively dryness in the field caused an important decrease in the viable population.

IMPORTANCE The v-qPCR method in combination with plate counting and qPCR is a powerful tool for studies of colonization and survival under field conditions, to improve formulations and delivery strategies of PM411, and to optimize the dose and timing of spray schedules. It is expected that PEMAX v-qPCR could also be developed for monitoring other strains on plant surfaces not only as biological control agents but also beneficial bacteria useful in the sustainable management of crop production.

Molecular typing of Lactobacillus brevis isolates from Korean food using repetitive element-polymerase chain reaction

Lactobacillus brevis is a part of a large family of lactic acid bacteria that are present in cheese, sauerkraut, sourdough, silage, cow manure, feces, and the intestinal tract of humans and rats. It finds its use in food fermentation, and so is considered a "generally regarded as safe" organism. L. brevis strains are extensively used as probiotics and hence, there is a need for identifying and characterizing these strains. For identification and discrimination of the bacterial species at the subspecific level, repetitive element-polymerase chain reaction method is a reliable genomic fingerprinting tool. The objective of the present study was to characterize 13 strains of L. brevis isolated from various fermented foods using repetitive element-polymerase chain reaction. Repetitive element-polymerase chain reaction was performed using three primer sets, REP, Enterobacterial Repetitive Intergenic Consensus (ERIC), and (GTG)₅, which produced different fingerprinting patterns that enable us to distinguish between the closely related strains. Fingerprinting patterns generated band range in between 150 and 5000 bp with REP, 200-7500 bp with ERIC, and 250-2000 bp with (GTG)₅ primers, respectively. The Jaccard's dissimilarity matrices were used to obtain dendrograms by the unweighted neighbor-joining method using genetic dissimilarities based on repetitive element-polymerase chain reaction fingerprinting data. Repetitive element-polymerase chain reaction proved to be a rapid and easy method that can produce reliable results in L. brevis species.

Probiotic strains and mechanistic insights for the treatment of type 2 diabetes

INTRODUCTION

The intestinal microbial composition appears to differ between healthy controls and individuals with Type 2 diabetes (T2D). This observation has led to the hypothesis that perturbations of the intestinal microbiota may contribute to the development of T2D. Manipulations of the intestinal microbiota may therefore provide a novel approach in the prevention and treatment of T2D. Indeed, fecal transplants have shown promising results in both animal models for obesity and T2D and in human clinical trials. To avoid possible complications associated with fecal transplants, probiotics are considered as a viable alternative therapy. An important, however often underappreciated, characteristic of probiotics is that individual strains may have different, even opposing, effects on the host. This strain specificity exists also within the same species. A comprehensive understanding of the underlying mechanisms at the strain level is therefore crucial for the selection of suitable probiotic strains.

PURPOSE

The aim of this review is to discuss the mechanisms employed by specific probiotic strains of the Lactobacillus and the Bifidobacterium genuses, which showed efficacy in the treatment of obesity and T2D. Some probiotic strains employ recurring beneficial effects, including the production of anti-microbial lactic acid, while other strains display highly unique features, such as hydrolysis of tannins.

CONCLUSION

A major obstacle in the evaluation of probiotic strains lays in the great number of strains, differences in detection methodology and measured outcome parameters. The understanding of further research should be directed towards the development of standardized evaluation methods to facilitate the comparison of different studies.

Lactobacillus rhamnosus GG: An Overview to Explore the Rationale of Its Use in Cancer

Cancer is the second leading cause of death in the western world. In the era of precision medicine, a significant number of cancer patients can be cured with several anti-cancer therapeutic regimens. However, therapy failure may be caused by treatment side effects, such as diarrhea, especially occurring in patients with gastrointestinal or pelvic malignancies. In particular, diarrhea is one of the most frequent gastrointestinal toxicity during cancer treatment and it can result from nearly bot chemo- and radio-therapeutic strategies currently used. Diarrhea has a serious impact on patients’ quality of life and treatment dosing and schedule modification due to its severity can negatively influence treatment outcomes. In this context, probiotics may play an interesting role in several human diseases with an inflammatory bowel involvement and, among these, Lactobacillus rhamnosus GG (LGG) is one of the most characterized and utilized. In particular, LGG is able to reverse intestinal dysbiosis and moderate diarrhea. Moreover, preclinical studies have documented its effects in reducing chronic inflammation associated with cancer development. This review summarizes the preclinical results of LGG on cancer cells proliferation and tumor invasion as well as the potential role of LGG use in cancer patients for the prevention and management of diarrhea associated with cancer treatment. Overall, these encouraging data support further investigation on the use of LGG in stratified patients undergoing specific therapeutic protocols, including chemotherapy and pelvic radiotherapy, in order to reduce the development of severe diarrhea and thus improve the adherence to the therapy and patients’ quality of life.

Comprehensive analysis of the fecal microbiota of healthy Japanese adults reveals a new bacterial lineage associated with a phenotype characterized by a high frequency of bowel movements and a lean body type

Background

In Japan, a variety of traditional dietary habits and daily routines have developed in many regions. The effects of these behaviors, and the regional differences in the composition of the gut microbiota, are yet to be sufficiently studied. To characterize the Japanese gut microbiota and identify the factors shaping its composition, we conducted 16S metagenomics analysis of fecal samples collected from healthy Japanese adults residing in various regions of Japan. Each participant also completed a 94-question lifestyle questionnaire.

Results

We collected fecal samples from 516 healthy Japanese adults (325 females, 191 males; age, 21–88). Heatmap and biplot analyses based on the bacterial family composition of the fecal microbiota showed that subjects’ region of residence or gender were not strongly correlated with the general composition of the fecal microbiota. Although clustering analysis for the whole cohort did not reveal any distinct clusters, two enterotype-like clusters were observed in the male, but not the female, subjects.

In the whole subject population, the scores for bowel movement frequency were significantly correlated with the abundances of Christensenellaceae, Mogibacteriaceae, and Rikenellaceae in the fecal microbiota (P < 0.001). These three bacterial families were also significantly more abundant (P < 0.05 or 0.01) in lean subjects (body mass index (BMI) < 25) than in obese subjects (BMI > 30), which is consistent with previously published results. However, a previously reported correlation between BMI and bowel movement frequency was not observed. In addition, the abundances of these three families were positively correlated with each other and comprised a correlative network with 14 other bacterial families.

Conclusions

The present study showed that the composition of the fecal microbiota of healthy Japanese adults at the national level was not strongly correlated with subjects’ area of residence or gender. In addition, enterotype partitioning was ambiguous in this cohort of healthy Japanese adults. Finally, the results implied that the abundances of Christensenellaceae, Mogibacteriaceae, and Rikenellaceae, along with several other bacterial components that together comprised a correlative network, contributed to a phenotype characterized by a high frequency of bowel movements and a lean body type.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0898-x) contains supplementary material, which is available to authorized users.

Vaginal Microbiota

The knowledge about the normal and abnormal vaginal microbiome has changed over the last years. Culturing techniques are not suitable any more for determination of a normal or abnormal vaginal microbiota. Non culture-based modern technologies revealed a complex and dynamic system mainly dominated by lactobacilli.The normal and the abnormal vaginal microbiota are complex ecosystems of more than 200 bacterial species influenced by genes, ethnic background and environmental and behavioral factors. Several species of lactobacilli per individuum dominate the healthy vagina. They support a defense system together with antibacterial substances, cytokines, defensins and others against dysbiosis, infections and care for an normal pregnancy without preterm birth.The numbers of Lactobacillus (L.) iners increase in the case of dysbiosis.Bacterial vaginosis (BV) - associated bacteria (BVAB), Atopobium vaginae and Clostridiales and one or two of four Gardnerella vaginalis - strains develop in different mixtures and numbers polymicrobial biofilms on the vaginal epithelium, which are not dissolved by antibiotic therapies according to guidelines and, thus, provoke recurrences.Aerobic vaginitis seems to be an immunological disorder of the vagina with influence on the microbiota, which is here dominated by aerobic bacteria (Streptococcus agalactiae, Escherichia coli). Their role in AV is unknown.Vaginal or oral application of lactobacilli is obviously able to improve therapeutic results of BV and dysbiosis.

Biodegradation of Ochratoxin A by Bacterial Strains Isolated from Vineyard Soils

Ochratoxin A (OTA) is a mycotoxin with a main nephrotoxic activity contaminating several foodstuffs. In the present report, five soil samples collected from OTA-contaminated vineyards were screened to isolate microorganisms able to biodegrade OTA. When cultivated in OTA-supplemented medium, OTA was converted in OTα by 225 bacterial isolates. To reveal clonal relationships between isolates, molecular typing by using an automated rep-PCR system was carried out, thus showing the presence of 27 different strains (rep-PCR profiles). The 16S-rRNA gene sequence analysis of an isolate representative of each rep-PCR profiles indicated that they belonged to five bacterial genera, namely Pseudomonas, Leclercia, Pantoea, Enterobacter, and Acinetobacter. However, further evaluation of OTA-degrading activity by the 27 strains revealed that only Acinetobacter calcoaceticus strain 396.1 and Acinetobacter sp. strain neg1, consistently conserved the above property; their further characterization showed that they were able to convert 82% and 91% OTA into OTα in six days at 24 °C, respectively. The presence of OTα, as the unique OTA-degradation product was confirmed by LC-HRMS. This is the first report on OTA biodegradation by bacterial strains isolated from agricultural soils and carried out under aerobic conditions and moderate temperatures. These microorganisms might be used to detoxify OTA-contaminated feed and could be a new source of gene(s) for the development of a novel enzymatic detoxification system.

Lactobacillus rhamnosus GG suspected infection in a newborn with intrauterine growth restriction

A disseminated Lactobacillus rhamnosus GG ATCC 53103 infection was suspected in a 6 day-old newborn with intrauterine growth restriction (IUGR) symptoms, treated empirically with antibiotics and given L. rhamnosus GG with the aim of preventing antibiotic-associated gastrointestinal complications. The level of C-reactive protein on day 5 compared with day 2 was increased in spite of negative urine and cerebrospinal fluid cultures. The blood sampled on day 6 was found to be positive for lactobacilli, and the isolate was pre-identified as L. rhamnosus or Lactobacillus casei on day 11. The strain identity was then verified as L. rhamnosus GG through PCR and 16S rRNA sequencing. Genotyping with the rep-PCR and AFLP methods confirmed the 100% genetic similarity for both the strain isolated from patient blood and the probiotic product. The newborn became touch-sensitive, cried a lot, had worsening laboratory test results, and increased inflammation parameters, but no fever was observed. After a further 9 days of antibiotic therapy, blood cultures became negative, and laboratory tests improved on day 25. The patient was discharged from the hospital after 27 days. IUGR with a possible link to L. rhamnosus GG bacteraemia might be a new potential risk group, beside patients with organ failure, immunocompromised status and dysfunctional gut barrier mechanisms, for which safe use of probiotics needs careful attention. Universally accepted or improved guidelines for the safer administration of probiotics in risk groups are urgently needed. This report should not discourage the use of probiotics, but should highlight the need for their careful use in IUGR patients.

Strategies to develop strain-specific PCR based assays for probiotics

Since health benefits conferred by probiotics are strain-specific, identification to the strain level is mandatory to allow the monitoring of the presence and the abundance of specific probiotic in a product or in a gastrointestinal tract. Compared to standard plate counts, the reduced duration of the assays and higher specificity makes PCR-based methods (standard PCR and quantitative PCR) very appropriate for detection or quantification of probiotics. Development of strain-specific assay consists of 4 main stages: (1) strain-specific marker identification; (2) construction of potential strain-specific primers; (3) validation on DNA from pure cultures of target and related strains; and (4) validation on spiked samples. The most important and also the most challenging step is the identification of strain-specific sequences, which can be subsequently targeted by specific primers or probes. Such regions can be identified on sequences derived from 16S-23S internally transcribed spacers, randomly amplified polymorphic DNA, representational difference analysis and suppression subtractive hybridisation. Already known phenotypic or genotypic characteristics of the target strain can also be used to develop the strain-specific assay. However, the initial stage of strain-specific assay development can be replaced by comparative genomics analysis of target genome with related genomes in public databases. Advances in whole genome sequencing (WGS) have resulted in a cost reduction for bacterial genome sequencing and consequently have made this approach available to most laboratories. In the present paper I reviewed the available literature on PCR and qPCR assays developed for detection of a specific probiotic strain and discussed future WGS and comparative genomics-based approaches.

Probiotic features of Lactobacillus strains isolated from Ragusano and Pecorino Siciliano cheeses

In the present study 177 Lactobacillus spp. strains, isolated from Ragusano and Pecorino Siciliano cheeses, were in vitro screened for probiotic traits, and their characteristics were compared to those of Lactobacillus rhamnosus GG, commercial strain. Based on acidic and bile salt resistance, thirteen Lactobacillus strains were selected. The multiplex-PCR application revealed that nine strains belonged to L. rhamnosus species and four to Lactobacillus paracasei species. All selected strains were further investigated for transit tolerance in simulated upper gastrointestinal tract (GI), for adhesion capacity to human intestinal cell lines, for hydrophobicity, for co-aggregation and auto-aggregation and for antimicrobial activities. Moreover, antibiotic resistance, hemolytic and bile salt hydrolase activities were investigated for safety assessment. Viable counts after simulated gastric and duodenal transit revealed that overall the selected lactobacilli tolerated better pancreatic juice and bile salts than acidic juice. In particular, three L. rhamnosus strains (FS10, FS2, and PS11) and one L. paracasei strain (PM8) increased their cell density after the simulated GI transit. The same strains showed also high percentage of auto-aggregation and co-aggregation with Escherichia coli. All strains were effective against both Staphylococcus aureus and E. coli and variability was achieved versus Listeria monocytogenes and Enterococcus faecalis used as pathogenic indicator strains. Different behavior was revealed by strains for adhesion ability and hydrophobicity, which are not always linked each other and are strongly strain-dependent. From the safety point of view, no isolate showed hemolytic and bile salt hydrolase activities, except one, and most of the strains were sensitive to a broad range of clinical antibiotics. This work showed that the L. rhamnosus FS10 and the L. paracasei PM8 are good promising probiotic candidates for further in vivo investigations.

Influence of manufacturing processes on cell surface properties of probiotic strain Lactobacillus rhamnosus Lcr35®

The influence of the industrial process on the properties of probiotics, administered as complex manufactured products, has been poorly investigated. In the present study, we comparatively assessed the cell wall characteristics of the probiotic strain Lactobacillus rhamnosus Lcr35® together with three of its commercial formulations with intestinal applications. Putative secreted and transmembrane-protein-encoding genes were initially searched in silico in the genome of L. rhamnosus Lcr35®. A total of 369 candidate genes were identified which expressions were followed using a custom Lactobacillus DNA chip. Among them, 60 or 67 genes had their expression either upregulated or downregulated in the Lcr Restituo® packet or capsule formulations, compared to the native Lcr35® strain. Moreover, our data showed that the probiotic formulations (Lcr Lenio®, Lcr restituo® capsule and packet) showed a better capacity to adhere to intestinal epithelial Caco-2 cells than the native Lcr35® strain. Microbial (MATS) tests showed that the probiotic was an electron donor and that they were more hydrophilic than the native strain. The enhanced adhesion capacity of the active pharmaceutical ingredients (APIs) to epithelial Caco-2 cells and their antipathogen effect could be due to this greater surface hydrophilic character. These findings suggest that the manufacturing process influences the protein composition and the chemical properties of the cell wall. It is therefore likely that the antipathogen effect of the formulation is modulated by the industrial process. Screening of the manufactured products' properties would therefore represent an essential step in evaluating the effects of probiotic strains.

Severe oral infection due to Lactobacillus rhamnosus during induction chemotherapy for acute myeloid leukemia

We report a case of severe oral infection with a high fever due to Lactobacillus rhamnosus during induction chemotherapy for acute myeloid leukemia. The patient did not improve on treatment with meropenem, clindamycin, or vancomycin until neutrophil recovery. Since L. rhamnosus GG is used in dairy products, and the patient ingested dairy products daily before starting chemotherapy, we suspected an association between the ingestion of dairy products and the development of infection. Pulsed-field gel electrophoresis using two different restriction enzymes showed that the strain isolated from the patient was identical to the L. rhamnosus GG strain isolated from dairy products and ATCC #53103. This was confirmed by a PCR assay with species-specific L. rhamnosus GG primers. Since Lactobacillus infection, particularly L. rhamnosus infection, can be fatal in immunocompromised hosts, we should consider Lactobacillus as a causative organism when Gram-positive rods are detected during treatment with broad-spectrum antibiotics and vancomycin. The causal association between the ingestion of dairy products containing Lactobacillus and Lactobacillus infection in immunocompromised hosts warrants further study.

Mechanistic approach to stability studies as a tool for the optimization and development of new products based on L. rhamnosus Lcr35® in compliance with current regulations

Probiotics are of great current interest in the pharmaceutical industry because of their multiple effects on human health. To beneficially affect the host, an adequate dosage of the probiotic bacteria in the product must be guaranteed from the time of manufacturing to expiration date. Stability test guidelines as laid down by the ICH-Q1A stipulate a minimum testing period of 12 months. The challenge for producers is to reduce this time. In this paper, a mechanistic approach using the Arrhenius model is proposed to predict stability. Applied for the first time to laboratory and industrial probiotic powders, the model was able to provide a reliable mathematical representation of the effects of temperature on bacterial death (R²>0.9). The destruction rate (k) was determined according to the manufacturing process, strain and storage conditions. The marketed product demonstrated a better stability (k = 0.08 months⁻¹) than the laboratory sample (k = 0.80 months⁻¹). With industrial batches, k obtained at 6 months of studies was comparable to that obtained at 12 months, evidence of the model’s robustness. In addition, predicted values at 12 months were greatly similar (±30%) to those obtained by real-time assessing the model’s reliability. This method could be an interesting approach to predict the probiotic stability and could reduce to 6 months the length of stability studies as against 12 (ICH guideline) or 24 months (expiration date).

Development of a tiered multilocus sequence typing scheme for members of the Lactobacillus acidophilus complex

Members of the Lactobacillus acidophilus complex are associated with functional foods and dietary supplements because of purported health benefits they impart to the consumer. Many characteristics of these microorganisms are reported to be strain specific. Therefore, proper strain typing is essential for safety assessment and product labeling, and also for monitoring strain integrity for industrial production purposes. Fifty-two strains of the L. acidophilus complex (L. acidophilus, L. amylovorus, L. crispatus, L. gallinarum, L. gasseri, and L. johnsonii) were genotyped using two established methods and compared to a novel multilocus sequence typing (MLST) scheme. PCR restriction fragment length polymorphism (PCR-RFLP) analysis of the hsp60 gene with AluI and TaqI successfully clustered 51 of the 52 strains into the six species examined, but it lacked strain-level discrimination. Random amplified polymorphic DNA PCR (RAPD-PCR) targeting the M13 sequence resulted in highly discriminatory profiles but lacked reproducibility. In this study, an MLST scheme was developed using the conserved housekeeping genes fusA, gpmA, gyrA, gyrB, lepA, pyrG, and recA, which identified 40 sequence types that successfully clustered all of the strains into the six species. Analysis of the observed alleles suggests that nucleotide substitutions within five of the seven MLST loci have reached saturation, a finding that emphasizes the highly diverse nature of the L. acidophilus complex and our unconventional application of a typically intraspecies molecular typing tool. Our MLST results indicate that this method could be useful for characterization and strain discrimination of a multispecies complex, with the potential for taxonomic expansion to a broader collection of Lactobacillus species.

Microbial characterization of probiotics--advisory report of the Working Group "8651 Probiotics" of the Belgian Superior Health Council (SHC)

When ingested in sufficient numbers, probiotics are expected to confer one or more proven health benefits on the consumer. Theoretically, the effectiveness of a probiotic food product is the sum of its microbial quality and its functional potential. Whereas the latter may vary much with the body (target) site, delivery mode, human target population, and health benefit envisaged microbial assessment of the probiotic product quality is more straightforward. The range of stakeholders that need to be informed on probiotic quality assessments is extremely broad, including academics, food and biotherapeutic industries, healthcare professionals, competent authorities, consumers, and professional press. In view of the rapidly expanding knowledge on this subject, the Belgian Superior Health Council installed Working Group "8651 Probiotics" to review the state of knowledge regarding the methodologies that make it possible to characterize strains and products with purported probiotic activity. This advisory report covers three main steps in the microbial quality assessment process, i.e. (i) correct species identification and strain-specific typing of bacterial and yeast strains used in probiotic applications, (ii) safety assessment of probiotic strains used for human consumption, and (iii) quality of the final probiotic product in terms of its microbial composition, concentration, stability, authenticity, and labeling.

Phenotyping and genotyping are both essential to identify and classify a probiotic microorganism

The use of probiotic products, especially for humans, requires an unequivocal taxonomical definition of their microbial content, in order to assign the probiotic effects to well identified and characterized microbial strains. In the absence of this, the labeling of some marketed probiotics may be misleading, both in terms of microbiological contents and possible beneficial effects. Currently, the ‘polyphasic taxonomy’ based on the integration of phenotypic and genotypic data seems to be the most appropriate approach. In fact, even if phenotypic characters often overlap among genetically different species, the molecular methods alone are frequently not able to establish distinct boundaries among phylogenetically related species. Thus, a valid scheme for the identification of a probiotic strain should be currently based on its morphological, physiological, and biochemical features as well as on aspects of its genetic profile. It is important that the identity of specific probiotic strains appearing on the product label is the result of a carefully selected combination of suitable phenotypic and genotypic analytical methods. Only adoption of such a policy could give the right emphasis to the significance of strain-specificity and thus provide health authorities with accurate tools to better evaluate the health benefits claimed by each probiotic-based product. The most common phenotypic and genotypic methods are briefly reviewed here with the aim of highlighting the suitable techniques which can be used to differentiate among microorganisms of probiotic interest, particularly those claiming beneficial health effects for humans.

Evaluation of strain-specific primers for identification of Lactobacillus rhamnosus GG

Lactobacillus rhamnosus strain GG (ATCC 53103) is one of the most widely studied and commercialized probiotic strains, and thus strain-specific identification for the strain is highly valuable. In this study, two published PCR-based identification methods for strain GG, a transposase gene-targeting system and a phage-related gene-targeting system, were evaluated. The former produced amplicons from eight of the 41 strains tested and the phage-related system from five of the tested strains, including the strain GG. Fingerprinting analysis indicated that the strains LMG 18025, LMG 18030, and LMG 18038, which had an amplicon by the former system but none by the latter, were genetically distinguishable from L. rhamnosus GG at strain level. Strains LMG 23320, LMG 23325, LMG 23534, and LMG 25859 showed profiles very similar to that of the strain GG, suggesting that these strains might be identical to GG or derivative strains of it. The results here indicated that the phage-related gene-targeting system is a good tool for accurate identification of L. rhamnosus GG. This system would be able to detect both the original L. rhamnosus GG and its derivative strains.

Probiotics reduce gut microbial translocation and improve adult atopic dermatitis

BACKGROUND

It has been suggested that probiotics modulate atopic dermatitis (AD) progression, but no data are actually available on their mechanisms of action and on their ability to act as immunomodulators in this pathology.

OBJECTIVE

The aim of this randomized double-blinded active treatment versus placebo study was to evaluate clinical efficacy of an intake of a combination of 2 probiotics (Lactobacillus salivarius LS01 and Bifidobacterium breve BR03) for the treatment of adult AD patients.

METHODS

Forty-eight patients were enrolled in the study (randomization ratio 2:1) and treated with a combination (LS01 and BR03) or placebo (maltodextrin) for 12 weeks. Clinical efficacy was assessed from baseline by changes in the SCORAD index and DLQ index improvement. Analysis on the gut permeability barrier, immunologic parameters, and changes in fecal microbiota and recovery of probiotics were performed at baseline, at the end of therapy, and 2 months later.

RESULTS

Patients receiving probiotics showed a significant improvement in clinical parameters (SCORAD, P<0.0001 and DLQ index, P=0.021) from baseline. The probiotics reduced microbial translocation (P=0.050), immune activation (P<0.001), improved T-helper cell (Th)17/regulatory T cell (Treg) (P=0.029) and Th1/Th2 (P=0.028) ratios. None of these changes were observed in the placebo group.

CONCLUSIONS

Our results suggest that this specific mixture of probiotics (LS01 and BR03 strains) may induce beneficial effects for clinical and immunologic alterations in adult AD. This combination could be considered as adjuvant therapy for the treatment of AD in adult patients.

Vaginal impact of the oral administration of total freeze-dried culture of LCR 35 in healthy women

The use of probiotics in the prevention or treatment of some vaginal infections has been the subject of numerous studies. To assess the presence of Lactobacillus casei rhamnosus (LCR35) in the vagina after an oral administration, an open randomised pilot study was conducted on 20 healthy women of child-bearing age. Materials and Methods. 2 groups of 10 women were given a 28-day oral course, that is, at least 108 CFU/day (group 1) or 2 × 108 CFU/day (group 2) of LCR35. Nugent score and vaginal screening for LCR35 were undertaken before and after 28 days of treatment. Results. The mean Nugent score decreased in group 1 (−0,2) as well as in group 2 (−0,3). 10% of women in group 1 versus 40% of women in group 2 were carrying LCR35 at the end of the trial. Conclusion. LCR35, at the minimal dose of 2 × 108 CFU/day, can return the Nugent score to normal in healthy women of child-bearing age, by means of a well-tolerated vaginal temporary presence. Phase III clinical trials will specify the preventive or curative impact of this orally administered strain on a range of vaginal disorders such as bacterial vaginosis or vulvovaginal candidiasis.

Efficacy and safety profile of LCR35 complete freeze-dried culture in irritable bowel syndrome: A randomized, double-blind study

AIM: To assess the effects and safety of Lactobacillus casei rhamnosus LCR35 complete freeze-dried culture (LCR35) in patients suffering from irritable bowel syndrome (IBS).

METHODS: A randomized, double-blind pilot study was performed in 50 patients complaining of IBS symptoms complying with Rome III criteria. Patients were allocated to receive either LCR35 (n = 25) at a minimum daily dose of 6 × 10⁸ colony forming units or placebo (n = 25) for 4 wk. At inclusion, after treatment and 2 wk later, patients completed the IBS severity scale. Change from baseline in the IBS severity score at the end of treatment was the primary efficacy criterion. Changes were compared between groups in the whole population and in IBS subtypes (IBS with predominance of constipation, IBS with predominance of diarrhoea, mixed IBS, unsubtyped IBS). The presence of lactobacillus casei rhamnosus in stools was investigated at inclusion and at the end of treatment. The gastrointestinal quality of life questionnaire and the hospital anxiety and depression (HAD) scale were also completed.

RESULTS: Both groups were balanced for baseline characteristics. In 85% of patients, stool analyses showed that lactobacillus casei rhamnosus able to survive in the digestive tract. In the whole population, improvements in the IBS severity score did not differ significantly between treatments with a 25% decrease after 4-wk treatment, and a 15% decrease from baseline 2 wk later in both groups. In IBS subgroups, statistical analysis could not be performed due to small sample size, but a clinical response in favour of LCR35 was observed in IBS patients with predominance of diarrhoea: no change in the symptom severity score was seen with the placebo after 4 wk treatment, whereas a clinically relevant decrease occurred with LCR35 (-37% vs -3%). Furthermore, in spite of an increase in symptom intensity, the IBS severity score was maintained below the baseline value 2 wk later with LCR35 (-19% from baseline), whilst a slight 5% increase from baseline was observed with placebo. In the IBS subgroup with predominance of diarrhoea only, a clinically relevant decrease in abdominal pain severity score (-36%) was observed with LCR35, whereas no change occurred with placebo. In mixed IBS patients, the 20% and 30% decreases in the IBS severity score observed after treatment with LCR35 and placebo, respectively, were maintained 2 wk later in both groups. A clinical response slightly in favour of placebo was observed at the end of the treatment period in IBS patients with predominance of constipation (-41% vs -20%) and unsubtyped IBS patients (-47% vs -17%), with the same value maintained 2 wk later. In both groups, no clinically relevant changes were observed either for the gastrointestinal quality of life index or HAD score. Thus, these results suggest that sub-grouping of IBS patients may be important for optimizing treatment responses by the physician.

CONCLUSION: This pilot study suggests that LCR35 could have some efficacy in IBS patients complaining of diarrhoea. These preliminary results need to be confirmed in larger studies.

Diversity of spore-forming bacteria and identification of Bacillus amyloliquefaciens as a species frequently associated with the ropy spoilage of bread

This study examines the diversity of spore-forming bacteria isolated from raw materials/bread using molecular methods along with a rapid and innovative technology, the FT-NIR spectroscopy. Microbiological analysis showed that 23% of semolina and 42% of other raw materials (including grain, brewer yeast, improvers) contained more than 100 spores/g and more than 50% of each kind of sample was contaminated at a level ranging from 1 to 100 spores/g. A high bacterial diversity characterized raw materials. In total 176 isolates were collected and characterized: 13 bacterial species belonging to Bacillus (10) and Paenibacillus (3) genera were identified by sequencing of 16S rRNA, gyrA or gyrB genes. The two closely related species Bacillus amyloliquefaciens (strain N45.1) and Bacillus subtilis (strain S63) were also analyzed by the spectroscopic technique FT-NIR. This analysis gave clear discrimination between the strains in the score plot obtained by the PCA and allowed to identify the spectral region 5600-4000 cm(-1) as the information-rich region for discrimination. B. amyloliquefaciens, possibly misidentified as B. subtilis in previous studies, was recognized as the most frequent species, found also in ropy bread. Moreover, the screening test for rope production indicated that mainly B. amyloliquefaciens, together with B. subtilis and Bacillus pumilus, could cause spoilage in bread, even if the last two species were represented by a low number of isolates. The Bacillus cereus group and Bacillus megaterium showed a lower percentage (30-70%) of isolates potentially able to cause the rope, but considering the high number of B. cereus group isolates detected in this study, this bacterial group should also be considered important in rope spoilage. In conclusion, results demonstrate that raw materials used to produce bread represent a rich source of spore-forming bacteria, therefore their microbiological quality should be monitored before use. Moreover, this study highlights for the first time the importance of the species B. amyloliquefaciens in rope spoilage and indicates that other species may also cause this alteration although strains of the same species may behave differently.

Discrimination of probiotic Lactobacillus strains for poultry by repetitive sequenced-based PCR fingerprinting

BACKGROUND

Four repetitive element sequence-based polymerase chain reaction (rep-PCR) methods, namely repetitive extragenic palindromic PCR (REP-PCR), enterobacterial repetitive intergenic consensus PCR (ERIC-PCR), polytrinucleotide (GTG)₅ -PCR and BOX-PCR, were evaluated for the molecular differentiation of 12 probiotic Lactobacillus strains previously isolated from the gastrointestinal tract of chickens and used as a multistrain probiotic. This study represents the first analysis of the comparative efficacy of these four rep-PCR methods and their combination (composite rep-PCR) in the molecular typing of Lactobacillus strains based on a discriminatory index (D).

RESULTS

Species-specific and strain-specific profiles were observed from rep-PCR. From the numerical analysis of composite rep-PCR, BOX-PCR, (GTG)₅ -PCR, REP-PCR and ERIC-PCR, D values of 0.9118, 0.9044, 0.8897, 0.8750 and 0.8529 respectively were obtained. Composite rep-PCR analysis was the most discriminative method, with eight Lactobacillus strains, namely L. brevis ATCC 14869(T) , L. reuteri C 10, L. reuteri ATCC 23272(T) , L. gallinarum ATCC 33199(T) , L. salivarius ATCC 11741(T) , L. salivarius I 24, L. panis JCM 11053(T) and L. panis C 17, being differentiated at the strain level.

CONCLUSION

Composite rep-PCR analysis is potentially a useful fingerprinting method to discriminate probiotic Lactobacillus strains isolated from the gastrointestinal tract of chickens.

Antimicrobial susceptibility of Lactobacillus rhamnosus

We aimed to determine the minimum inhibitory concentrations (MICs) of Lactobacillus rhamnosus (n=75) strains, to study their antibiotic resistance genes with microarray, and to assess the microbiological cut-off values of tested antimicrobial agents. L. rhamnosus strains were tested with agar dilution, broth microdilution and Etest methods for ampicillin, clindamycin, erythromycin, gentamicin, streptomycin, and tetracycline using specific LSM medium. Most of the L. rhamnosus strains were found phenotypically susceptible to all six antibiotics tested. Four of the strains were phenotypically multiresistant, three strains to clindamycin, erythromycin and streptomycin and one strain to streptomycin and tetracycline. Some of the resistant (n=8) and susceptible (n=5) strains were further studied with a microarray method to reveal the antibiotic resistance genes behind the phenotypic resistances. From our experience, we recommend that microbiological cut-off values should be proposed according to the method used.

Dose-dependent immunomodulation of human dendritic cells by the probiotic Lactobacillus rhamnosus Lcr35

The response of the immune system to probiotics remains controversial. Some strains modulate the cytokine production of dendritic cells (DCs) in vitro and induce a regulatory response, while others induce conversely a pro-inflammatory response. These strain-dependent effects are thought to be linked to specific interactions between bacteria and pattern recognition receptors. We investigated the effects of a well characterized probiotic strain, Lactobacillus rhamnosus Lcr35, on human monocyte-derived immature DCs, using a wide range of bacterial concentrations (multiplicity of infection, MOI, from 0.01 to 100). DNA microarray and qRT-PCR analysis showed that the probiotic induced a large-scale change in gene expression (nearly 1,700 modulated genes, with 3-fold changes), but only with high doses (MOI, 100). The upregulated genes were mainly involved in immune response and identified a molecular signature of inflammation according to the model of Torri. Flow cytometry analysis also revealed a dose-dependent maturation of the DC membrane phenotype, until DCs reached a semi-mature state, with an upregulation of the membrane expression of CD86, CD83, HLA-DR and TLR4, associated with a down-regulation of DC-SIGN, MR and CD14. Measurement of the DC-secreted cytokines showed that Lcr35 induced a strong dose-dependent increase of the pro-Th1/Th17 cytokine levels (TNFα, IL-1β, IL-12p70, IL-12p40 and IL-23), but only a low increase in IL-10 concentration. The probiotic L. rhamnosus Lcr35 therefore induce a dose-dependent immunomodulation of human DCs leading, at high doses, to the semi-maturation of the cells and to a strong pro-inflammatory effect. These results contribute to a fuller understanding of the mechanism of action of this probiotic, and thus of its potential clinical indications in the treatment of either infectious or IgE-dependent allergic diseases.

Quantification of Propionibacterium acidipropionici P169 bacteria in environmental samples by use of strain-specific primers derived by suppressive subtractive hybridization

A quantitative PCR (qPCR) assay targeting a gene identified by suppressive subtractive hybridization (SSH) was developed to detect Propionibacterium acidipropionici P169, with a threshold of 10(4) CFU/U of dairy feed or rumen fluid. The report is the first using a molecular marker generated by SSH to quantify a bacterial strain in environmental samples.