Novel approaches for the taxonomic and metabolic characterization of lactobacilli: Integration of 16S rRNA gene sequencing with MALDI-TOF MS and 1H-NMR

A Snapshot, Using a Multi-Omic Approach, of the Metabolic Cross-Talk and the Dynamics of the Resident Microbiota in Ripening Cheese Inoculated with Listeria innocua

Raw milk cheeses harbor complex microbial communities. Some of these microorganisms are technologically essential, but undesirable microorganisms can also be present. While most of the microbial dynamics and cross-talking studies involving interaction between food-derived bacteria have been carried out on agar plates in laboratory-controlled conditions, the present study evaluated the modulation of the resident microbiota and the changes of metabolite production directly in ripening raw milk cheese inoculated with Listeria innocua strains. Using a proxy of the pathogenic Listeria monocytogenes, we aimed to establish the key microbiota players and chemical signals that characterize Latteria raw milk cheese over 60 days of ripening time. The microbiota of both the control and Listeria-inoculated cheeses was analyzed using 16S rRNA targeted amplicon sequencing, while direct analysis in real time mass spectrometry (DART-HRMS) was applied to investigate the differences in the metabolic profiles of the cheeses. The diversity analysis showed the same microbial diversity trend in both the control cheese and the inoculated cheese, while the taxonomic analysis highlighted the most representative genera of bacteria in both the control and inoculated cheese: Lactobacillus and Streptococcus. On the other hand, the metabolic fingerprints revealed that the complex interactions between resident microbiota and L. innocua were governed by continuously changing chemical signals. Changes in the amounts of small organic acids, hydroxyl fatty acids, and antimicrobial compounds, including pyroglutamic acid, hydroxy-isocaproic acid, malic acid, phenyllactic acid, and lactic acid, were observed over time in the L. innocua-inoculated cheese. In cheese that was inoculated with L. innocua, Streptococcus was significantly correlated with the volatile compounds carboxylbenzaldheyde and cyclohexanecarboxylic acid, while Lactobacillus was positively correlated with some volatile and flavor compounds (cyclohexanecarboxylic acid, pyroxidal acid, aminobenzoic acid, and vanillic acid). Therefore, we determined the metabolic markers that characterize a raw milk cheese inoculated with L. innocua, the changes in these markers with the ripening time, and the positive correlation of flavor and volatile compounds with the resident microbiota. This multi-omics approach could suggest innovative food safety strategies based on the enhanced management of undesirable microorganisms by means of strain selection in raw matrices and the addition of specific antimicrobial metabolites to prevent the growth of undesirable microorganisms.

Role of D(-)-Lactic Acid in Prevention of Chlamydia trachomatis Infection in an In Vitro Model of HeLa Cells

A vaginal microbiota dominated by certain Lactobacillus species may have a protective effect against Chlamydia trachomatis infection. One of the key antimicrobial compounds produced is lactic acid, which is believed to play a central role in host defense. Lactobacillus strains producing the D(-)-lactic acid isomer are known to exert stronger protection. However, the molecular mechanisms underlying this antimicrobial action are not well understood. The aim of this study was to investigate the role of D(-)-lactic acid isomer in the prevention of C. trachomatis infection in an in vitro HeLa cell model. We selected two strains of lactobacilli belonging to different species: a vaginal isolate of Lactobacillus crispatus that releases both D(-) and L(+) isomers and a strain of Lactobacillus reuteri that produces only the L(+) isomer. Initially, we demonstrated that L. crispatus was significantly more effective than L. reuteri in reducing C. trachomatis infectivity. A different pattern of histone acetylation and lactylation was observed when HeLa cells were pretreated for 24 h with supernatants of Lactobacillus crispatus or L. reuteri, resulting in different transcription of genes such as CCND1, CDKN1A, ITAG5 and HER-1. Similarly, distinct transcription patterns were found in HeLa cells treated with 10 mM D(-)- or L(+)-lactic acid isomers. Our findings suggest that D(-) lactic acid significantly affects two non-exclusive mechanisms involved in C. trachomatis infection: regulation of the cell cycle and expression of EGFR and α5β1-integrin.

Real-Life Assessment of the Ability of an Ultraviolet C Lamp (SanificaAria 200, Beghelli) to Inactivate Airborne Microorganisms in a Healthcare Environment

Airborne-mediated microbial diseases represent one of the major challenges to public health. Ultraviolet C radiation (UVC) is among the different sanitation techniques useful to reduce the risk of infection in healthcare facilities. Previous studies about the germicidal activity of UVC were mainly performed in artificial settings or in vitro models. This study aimed to assess the sanitizing effectiveness of a UVC device (SanificaAria 200, Beghelli, Valsamoggia, Bologna, Italy) in 'real-life' conditions by evaluating its ability to reduce microbial loads in several hospital settings during routine daily activities. The efficacy of the UVC lamp in reducing the bacterial component was evaluated by microbial culture through the collection of air samples in different healthcare settings at different times (30 min-24 h) after turning on the device. To assess the anti-viral activity, air samplings were carried out in a room where a SARS-CoV-2-positive subject was present. The UVC device showed good antibacterial properties against a wide range of microbial species after 6 h of activity. It was effective against possible multi-drug resistant microorganisms (e.g., Pseudomonas spp., Acinetobacter spp.) and spore-forming bacteria (e.g., Bacillus spp.). In addition, the UVC lamp was able to inactivate SARS-CoV-2 in just one hour. Thanks to its effectiveness and safety, SanificaAria 200 could be useful to inactivate airborne pathogens and reduce health risks.

16S rRNA gene sequencing and MALDI TOF mass spectroscopy identification of Leuconostoc mesenteroides isolated from Algerian raw camel milk

BACKGROUND

Eighty-three strains of Leuconostoc mesenteroides were isolated from Algerian raw camel milk. Based on morphological, biochemical, and physiological characters tests, strains were identified as Ln. mesenteroides subsp. mesenteroides. Seven strains had a remarkable antagonistic and probiotic characterization. The present study aims at identifying these strains by means of 16 s rRNA gene sequencing and Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), extending phenotypic and genotypic studies done previously.

RESULTS

The phyloproteomic dendrograms of the studied strains based on MALDI-TOF MS provided the same identification with more intraspecific information from the 16S rRNA gene sequencing based on phylogenetic analysis. The latter were in agreement with the previous biochemical/physiological identification, the seven isolated strains were Ln. mesenteroides subsp. mesenteroides.

CONCLUSIONS

Remarkably, MALDI-TOF MS fingerprinting was found to be effective enough as 16S rRNA gene sequencing identification, allowing faster and more reliable analysis than biochemical/physiological methods.

Exopolysaccharides from vaginal lactobacilli modulate microbial biofilms

BACKGROUND

Exopolysaccharides (EPS) secreted by beneficial lactobacilli exert a plethora of positive activities, but little is known about their effects on biofilms of opportunistic vaginal pathogens and especially on biofilms of lactobacilli themselves. Here, the EPS produced by six vaginal lactobacilli, belonging to Lactobacillus crispatus (BC1, BC4, BC5) and Lactobacillus gasseri (BC9, BC12, BC14) species were isolated from cultural supernatants and lyophilized.

RESULTS

Lactobacillus EPS were chemically characterized in terms of monosaccharide composition by liquid chromatography (LC) analysis coupled to UV and mass spectrometry (MS) detection. Moreover, the ability of EPS (0.1, 0.5, 1 mg/mL) to stimulate the biofilm formation of lactobacilli and to inhibit the formation of pathogens' biofilms was evaluated by crystal violet (CV) staining and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Isolated EPS (yields 133-426 mg/L) were heteropolysaccharides mainly composed of D-mannose (40-52%) and D-glucose (11-30%). For the first time we demonstrated that Lactobacillus EPS were able to stimulate in a dose-dependent manner (p < 0.05) the formation of biofilms of ten strains belonging to L. crispatus, L. gasseri and Limosilactobacillus vaginalis species, in terms of cell viability (84-282% increase at 1 mg/mL) and especially biofilm biomass (40-195% increase at 1 mg/mL), quantified with MTT assay and CV staining, respectively. EPS released from L. crispatus and L. gasseri were found to better stimulate the biofilms of the same producer species rather than that of other species, including producing strains themselves and other strains. Conversely, the biofilm formation of bacterial (Escherichia coli, Staphylococcus spp., Enterococcus spp. and Streptococcus agalactiae) and fungal (Candida spp.) pathogens was inhibited. The anti-biofilm activity was dose-dependent and was more marked for L. gasseri-derived EPS (inhibition up to 86%, 70%, and 58% at 1 mg/mL, 0.5 mg/mL, and 0.1 mg/mL, respectively), whilst L. crispatus-derived EPS resulted overall less efficient (inhibition up to 58% at 1 mg/mL and 40% at 0.5 mg/mL) (p < 0.05).

CONCLUSIONS

Lactobacilli-derived EPS favour the biofilm formation of lactobacilli preventing, at the same time, that of opportunistic pathogens. These results support the possible employment of EPS as postbiotics in medicine as a therapeutic/preventive strategy to counteract vaginal infections.

A novel species of lactic acid bacteria, Ligilactobacillus pabuli sp. nov., isolated from alfalfa silage

In this study, we isolated a novel strain of lactic acid bacteria, AF129T, from alfalfa silage prepared locally in Morioka, Iwate, Japan. Polyphasic taxonomy was used to characterize the bacterial strain. The bacterium was rod-shaped, Gram-stain-positive, non-spore-forming and catalase-negative. The strain grew at various temperatures (15–40°C) and pH levels (4.0–8.0). The optimum growth conditions were a temperature of 30°C and a pH of 6.0. AF129T exhibited growth at salt (NaCl) concentrations of up to 6.5 % (w/v). The G+C content of the strain’s genomic DNA was 41.5 %. The major fatty acids were C16 : 0, C18 : 1ω9c, C19 : 0cyclo ω8c and summed feature 8. 16S rRNA gene sequencing revealed that AF129T represents a member of the genus Ligilactobacillus and it has higher sequence similarities with Ligilactobacillus pobuzihii (98.4 %), Ligilactobacillus acidipiscis (97.5 %) and Ligilactobacillus salitolerans (97.4 %). The digital DNA–DNA hybridization values for AF129T and phylogenetically related species of the genus Ligilactobacillus ranged from 19.8% to 24.1%. The average nucleotide identity of the strain with its closely related taxa was lower than the threshold (95 %–96 %) used for species differentiation. In the light of the above-mentioned physiological, genotypic, chemotaxonomic and phylogenetic evidence, we confirm that AF129T represents a member of the genus Ligilactobacillus and constitutes a novel species; we propose the name Ligilactobacillus pabuli sp. nov. for this species. The type strain is AF129T =MAFF 518002T =JCM 34518T=BCRC 81335T.

An Updated Review on Prebiotics: Insights on Potentials of Food Seeds Waste as Source of Potential Prebiotics

Prebiotics are a group of biological nutrients that are capable of being degraded by microflora in the gastrointestinal tract (GIT), primarily Lactobacilli and Bifidobacteria. When prebiotics are ingested, either as a food additive or as a supplement, the colonic microflora degrade them, producing short-chain fatty acids (SCFA), which are simultaneously released in the colon and absorbed into the blood circulatory system. The two major groups of prebiotics that have been extensively studied in relation to human health are fructo-oligosaccharides (FOS) and galactooligosaccharides (GOS). The candidature of a compound to be regarded as a prebiotic is a function of how much of dietary fiber it contains. The seeds of fruits such as date palms have been reported to contain dietary fiber. An increasing awareness of the consumption of fruits and seeds as part of the daily diet, as well as poor storage systems for seeds, have generated an enormous amount of seed waste, which is traditionally discarded in landfills or incinerated. This cultural practice is hazardous to the environment because seed waste is rich in organic compounds that can produce hazardous gases. Therefore, this review discusses the potential use of seed wastes in prebiotic production, consequently reducing the environmental hazards posed by these wastes.

First-Void Urine Microbiome in Women with Chlamydia trachomatis Infection

Background: Chlamydia trachomatis (CT) is the agent of the most common bacterial sexually transmitted infection worldwide. Until now, little information is available about the microbial composition of urine samples during CT urethritis. Therefore, in this study, we characterized the microbiome and metabolome profiles of first-void urines in a cohort of women with CT urethral infection attending an STI clinic. Methods: Based on CT positivity by nucleic acid amplification techniques on urine samples, the enrolled women were divided into two groups, i.e., “CT-negative” (n = 21) and “CT-positive” (n = 11). Urine samples were employed for (i) the microbiome profile analysis by means of 16s rRNA gene sequencing and (ii) the metabolome analysis by ¹H-NMR. Results: Irrespective of CT infection, the microbiome of first-void urines was mainly dominated by Lactobacillus, L. iners and L. crispatus being the most represented species. CT-positive samples were characterized by reduced microbial biodiversity compared to the controls. Moreover, a significant reduction of the Mycoplasmataceae family—in particular, of the Ureaplasma parvum species—was observed during CT infection. The Chlamydia genus was positively correlated with urine hippurate and lactulose. Conclusions: These data can help elucidate the pathogenesis of chlamydial urogenital infections, as well as to set up innovative diagnostic and therapeutic approaches.

A Deep Look at the Vaginal Environment During Pregnancy and Puerperium

A deep comprehension of the vaginal ecosystem may hold promise for unraveling the pathophysiology of pregnancy and may provide novel biomarkers to identify subjects at risk of maternal-fetal complications. In this prospective study, we assessed the characteristics of the vaginal environment in a cohort of pregnant women throughout their different gestational ages and puerperium. Both the vaginal bacterial composition and the vaginal metabolic profiles were analyzed. A total of 63 Caucasian women with a successful pregnancy and 9 subjects who had a first trimester miscarriage were enrolled. For the study, obstetric examinations were scheduled along the three trimester phases (9-13, 20-24, 32-34 gestation weeks) and puerperium (40-55 days after delivery). Two vaginal swabs were collected at each time point, to assess the vaginal microbiome profiling (by Nugent score and 16S rRNA gene sequencing) and the vaginal metabolic composition (1H-NMR spectroscopy). During pregnancy, the vaginal microbiome underwent marked changes, with a significant decrease in overall diversity, and increased stability. Over time, we found a significant increase of Lactobacillus and a decrease of several genera related to bacterial vaginosis (BV), such as Prevotella, Atopobium and Sneathia. It is worth noting that the levels of Bifidobacterium spp. tended to decrease at the end of pregnancy. At the puerperium, a significantly lower content of Lactobacillus and higher levels of Gardnerella, Prevotella, Atopobium, and Streptococcus were observed. Women receiving an intrapartum antibiotic prophylaxis for Group B Streptococcus (GBS) were characterized by a vaginal abundance of Prevotella compared to untreated women. Analysis of bacterial relative abundances highlighted an increased abundance of Fusobacterium in women suffering a first trimester abortion, at all taxonomic levels. Lactobacillus abundance was strongly correlated with higher levels of lactate, sarcosine, and many amino acids (i.e., isoleucine, leucine, phenylalanine, valine, threonine, tryptophan). Conversely, BV-associated genera, such as Gardnerella, Atopobium, and Sneathia, were related to amines (e.g., putrescine, methylamine), formate, acetate, alcohols, and short-chain fatty-acids (i.e., butyrate, propionate).

The Role of Fatty Acid Metabolites in Vaginal Health and Disease: Application to Candidiasis

Although the vast majority of women encounters at least one vaginal infection during their life, the amount of microbiome-related research performed in this area lags behind compared to alternative niches such as the intestinal tract. As a result, effective means of diagnosis and treatment, especially of recurrent infections, are limited. The role of the metabolome in vaginal health is largely elusive. It has been shown that lactate produced by the numerous lactobacilli present promotes health by limiting the chance of infection. Short chain fatty acids (SCFA) have been mainly linked to dysbiosis, although the causality of this relationship is still under debate. In this review, we aim to bring together information on the role of the vaginal metabolome and microbiome in infections caused by Candida. Vulvovaginal candidiasis affects near to 70% of all women at least once in their life with a significant proportion of women suffering from the recurrent variant. We assess the role of fatty acid metabolites, mainly SCFA and lactate, in onset of infection and virulence of the fungal pathogen. In addition, we pinpoint where lack of research limits our understanding of the molecular processes involved and restricts the possibility of developing novel treatment strategies.

Insight into phenotypic and genotypic differences between vaginal Lactobacillus crispatus BC5 and Lactobacillus gasseri BC12 to unravel nutritional and stress factors influencing their metabolic activity

The vaginal microbiota, normally characterized by lactobacilli presence, is crucial for vaginal health. Members belonging to L. crispatus and L. gasseri species exert crucial protective functions against pathogens, although a total comprehension of factors that influence their dominance in healthy women is still lacking. Here we investigated the complete genome sequence and comprehensive phenotypic profile of L. crispatus strain BC5 and L. gasseri strain BC12, two vaginal strains featured by anti-bacterial and anti-viral activities. Phenotype microarray (PM) results revealed an improved capacity of BC5 to utilize different carbon sources as compared to BC12, although some specific carbon sources that can be associated to the human diet were only metabolized by BC12, i.e. uridine, amygdalin, tagatose. Additionally, the two strains were mostly distinct in the capacity to utilize the nitrogen sources under analysis. On the other hand, BC12 showed tolerance/resistance towards twice the number of stressors (i.e. antibiotics, toxic metals etc.) with respect to BC5. The divergent phenotypes observed in PM were supported by the identification in either BC5 or BC12 of specific genetic determinants that were found to be part of the core genome of each species. The PM results in combination with comparative genome data provide insights into the possible environmental factors and genetic traits supporting the predominance of either L. crispatus BC5 or L. gasseri BC12 in the vaginal niche, giving also indications for metabolic predictions at the species level.

Vaginal metabolic profiles during pregnancy: Changes between first and second trimester

During pregnancy, the vaginal microbiome plays an important role in both maternal and neonatal health outcomes. Throughout pregnancy, the vaginal microbial composition undergoes significant changes, including a decrease in overall diversity and enrichment with Lactobacillus spp. In turn, the modifications in the microbial profiles are associated with shifts in the composition of vaginal metabolites. In this study, we characterized the vaginal metabolic profiles throughout pregnancy at two different gestational ages, correlating them with a microscopic evaluation of the vaginal bacterial composition. A total of 67 Caucasian pregnant women presenting to the Family Advisory Health Centres of Ravenna (Italy) were enrolled and a vaginal swab was collected at gestational ages 9–13 weeks (first trimester) and 20–24 weeks (second trimester). The composition of the vaginal microbiome was assessed by Nugent score and women were divided in ‘H’ (normal lactobacilli-dominated microbiota), ‘I’ (intermediate microbiota), and ‘BV’ (bacterial vaginosis) groups. Starting from the cell-free supernatants of the vaginal swabs, a metabolomic analysis was performed by means of a ¹H-NMR spectroscopy. From the first to the second trimester, a greater number of women showed a normal lactobacilli-dominated microbiota, with a reduction of cases of dysbiosis. These microbial shifts were associated with profound changes in the vaginal metabolic profiles. Over the weeks, a significant reduction in the levels of BV-associated metabolites (e.g. acetate, propionate, tyramine, methylamine, putrescine) was observed. At the same time, the vaginal metabolome was characterized by higher concentrations of lactate and of several amino acids (e.g. tryptophan, threonine, isoleucine, leucine), typically found in healthy vaginal conditions. Over time, the vaginal metabolome became less diverse and more homogeneous: in the second trimester, women with BV showed metabolic profiles more similar to the healthy/intermediate groups, compared to the first trimester. Our data could help unravel the role of vaginal metabolites in the pathophysiology of pregnancy.

Assessment of the potential use of MALDI-TOF MS for the identification of bacteria associated with chilled vacuum-packaged lamb meat

The focus of this study was to compare the effectiveness of MALDI-TOF MS and partial 16S rRNA gene sequencing for the identification of bacteria isolated from VP lamb meat stored chilled at 5 °C for 21 days, at the same time gaining insights into bacterial changes over time. The identity of bacterial isolates on non-selective and selective agars was determined by both methods and results compared. Results showed that total bacterial numbers increased over the 21 days (as expected) with Staphylococcus and Pseudomonas (day 0) being replaced by Carnobacterium, Brochothrix and members of the Enterobacteriaceae family by day 21. A high level of agreement (86-100%) for bacterial isolates' identity at genus level was observed between MALDI-TOF MS and partial 16S rRNA gene-based sequencing for isolates where identification was possible. With its cheaper cost and faster turnaround time, once optimized, MALDI-TOF MS could become a useful alternative to 16S rRNA gene-sequencing for the rapid identification of red meat bacterial isolates.

Metabolic profiling of Candida clinical isolates of different species and infection sources

Candida species are the most common cause of opportunistic fungal infections. Rapid identification and novel approaches for the characterization of these fungi are of great interest to improve the diagnosis and the knowledge about their pathogenic properties. This study aimed to characterize clinical isolates of Candida spp. by proteomics (MALDI-TOF MS) and metabolomics (1H-NMR), and to correlate their metabolic profiles with Candida species, source of infection and different virulence associated parameters. In particular, 49 Candida strains from different sources (blood, n = 15; vagina, n = 18; respiratory tract, n = 16), belonging mainly to C. albicans complex (61%), C. glabrata (20%) and C. parapsilosis (12%) species were used. Several extracellular and intracellular metabolites showed significantly different concentrations among isolates recovered from different sources of infection, as well as among different Candida species. These metabolites were mainly related to the glycolysis or gluconeogenesis, tricarboxylic acid cycle, nucleic acid synthesis and amino acid and lipid metabolism. Moreover, we found specific metabolic fingerprints associated with the ability to form biofilm, the antifungal resistance (i.e. caspofungin and fluconazole) and the production of secreted aspartyl proteinase. In conclusion, 1H-NMR-based metabolomics can be useful to deepen Candida spp. virulence and pathogenicity properties.

The mechanisms and safety of probiotics against toxigenic clostridium difficile

INTRODUCTION

Toxigenic Clostridium difficile (C. difficile) is the main cause of antibiotic-associated diarrhea and can induce pseudomembranous colitis and infrequent toxic megacolon, which are potentially fatal. The standard antibiotic therapy for C. difficile infection (CDI) is limited by antibiotics' broad spectrum and further disruptive effects on indigenous microbiota. Probiotics may offer a prospective and alternative strategy for the prevention and treatment of CDI.

AREAS COVERED

In this article, the mechanisms implying the probiotic effect against C. difficile and the safety profile highlighting the patient groups with inappropriate application of probiotics were reviewed from 2015 to 2020.

EXPERT OPINION

Although many strains with ability against C. difficile have been reported, the usage of probiotics for CDI prevention and/or treatment is scarce since the number of clinical trials is not sufficient to prove probiotics' efficacy and safety in CDI treatment, especially for premature infant and immunocompromised patient. Especially, there are few well-defined clinical studies supporting safety of probiotics for CDI. A few strains from Lactobacillus and Saccharomyces genus have been studied more extensively than other probiotic strains through clinical trials for CDI. Thus, more clinical intervention studies regarding the benefit and the comprehensive safety assessments of probiotics for CDI are needed.

Influence of High Hydrostatic Pressure on the Identification of Lactobacillus by MALDI-TOF MS- Preliminary Study

In the present study, we assessed the ability of MALDI-TOF MS (matrix-assisted laser desorption ionization time-of-flight mass spectrometry) to identify microbial strains subjected to high hydrostatic pressure (HHP) as a stress factor. Protein changes induced by HHP can affect the identification of microorganisms when the identification technique is based on the protein profile. We evaluated two methods, namely MALDI-TOF MS and 16S rDNA sequencing, as a valuable tool to identify Lactobacillus species isolated from spoiled food, juices and beers. The data obtained from the protein mass fingerprint analysis of some of the lactobacilli strains showed differences in unpressured and pressured mass spectrum profiles (MSPs), which influenced the results of the identification. Four out of 13 strains (30%) showed different MSP results for unpressured and pressured samples and these results did not overlap with the 16S rDNA identification results. The 16S rDNA sequencing method revealed that five unpressured strains (38%) and four pressured strains (40%) were identified correctly by MALDI-TOF MS. Both methods showed compatible results in 38% of unpressured strains and in 30% of pressured strains. Stress factors, cultivation methods or the natural environment from which the bacteria were derived can affect their protein profile and thus change the mass spectrum. It is necessary to expand the database with a wide range of mass spectra dedicated to a high-throughput study of the microorganisms derived from different environments.

Identification of Species and Subspecies of Lactic Acid Bacteria Present in Spanish Cheeses Type "Torta" by MALDI-TOF MS and pheS gene Analyses

Several artisanal cheeses are elaborated in European countries, being commonly curdled with rennets of animal origin. However, in some Spanish regions some cheeses of type “Torta” are elaborated using Cynara cardunculus L. rennets. Two of these cheeses, “Torta del Casar” and “Torta de Trujillo”, are elaborated in Cáceres province with ewe’s raw milk and matured over at least 60 days without starters. In this work, we identified the lactic acid bacteria present in these cheeses using MALDI-TOF MS and pheS gene analyses, which showed they belong to the species Lactobacillus curvatus, Lactobacillus diolivorans, Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus rhamnosus, Lactococcus lactis and Leuconostoc mesenteroides. The pheS gene analysis also allowed the identification of the subspecies La. plantarum subsp. plantarum, La. paracasei subsp. paracasei and Le. mesenteroides subsp. jonggajibkimchii. Low similarity values were found in this gene for some currently accepted subspecies of Lc. lactis and for the two subspecies of La. plantarum, and values near to 100% for the subspecies of Le. mesenteroides and La. paracasei. These results, which were confirmed by the calculated ANIb and dDDH values of their whole genomes, showed the need to revise the taxonomic status of these species and their subspecies.

Microbial Contamination of Medical Staff Clothing During Patient Care Activities: Performance of Decontamination of Domestic Versus Industrial Laundering Procedures

The efficacy of domestic laundering of healthcare staff clothing is still debated. This study aimed to compare the performance of decontamination of different domestic laundering with that of industrial laundering. Fourteen naturally contaminated white coats of healthcare workers (5 fabric squares from each coat) and fabric squares of artificially contaminated cotton cloth (30 fabric squares per each bacterial strain used) were included. Four domestic laundering procedures were performed; two different washing temperatures (40 °C and 90 °C) and drying (tumble dry and air dry) were used. All fabric squares were ironed. Presence of bacterial bioburden on the fabric squares after domestic and industrial laundering was investigated. None of the naturally contaminated fabric squares resulted completely decontaminated after any of the domestic washes. At 24, 48, and 72 h of incubation, bacterial growth was observed in all the laundered fabric squares. Besides environmental microorganisms, potentially pathogenic bacteria (i.e., Acinetobacter lwoffii, Micrococcus luteus, coagulase-negative staphylococci) were isolated. On the artificially contaminated fabric squares, the bioburden was reduced after the domestic laundries; nevertheless, both Gram-negative and -positive pathogenic bacteria were not completely removed. In addition, a contamination of the fabric squares by environmental Gram-negative bacteria was observed. In both the naturally and artificially contaminated fabric squares, no bacterial growth at all the time-points analyzed was observed after industrial laundering, which provided to be more effective in bacterial decontamination than domestic washes. For those areas requiring the highest level of decontamination, the use of specialized industrial laundry services should be preferred.

A Combined Proteomics, Metabolomics and In Vivo Analysis Approach for the Characterization of Probiotics in Large-Scale Production

The manufacturing processes of commercial probiotic strains may be affected in different ways in the attempt to optimize yield, costs, functionality, or stability, influencing gene expression, protein patterns, or metabolic output. Aim of this work is to compare different samples of a high concentration (450 billion bacteria) multispecies (8 strains) formulation produced at two different manufacturing sites, United States of America (US) and Italy (IT), by applying a combination of functional proteomics, metabolomics, and in vivo analyses. Several protein-profile differences were detected between IT- and US-made products, with Lactobacillus paracasei, Streptococcus thermophilus, and Bifidobacteria being the main affected probiotics/microorganisms. Performing proton nuclear magnetic spectroscopy (¹H-NMR), some discrepancies in amino acid, lactate, betaine and sucrose concentrations were also reported between the two products. Finally, we investigated the health-promoting and antiaging effects of both products in the model organism Caenorhabditis elegans. The integration of omics platforms with in vivo analysis has emerged as a powerful tool to assess manufacturing procedures.

Identification, Classification and Screening for γ-Amino-butyric Acid Production in Lactic Acid Bacteria from Cambodian Fermented Foods

Screening for various types of lactic acid bacteria (LAB) that form the biological agent γ-amino-butyric acid (GABA) is important to produce different kinds of GABA-containing fermented foods. So far, no GABA-producing LAB have been reported from Cambodian fermented foods. Most small-scale fermentations and even some industrial processes in this country still rely on indigenous LAB. The application of GABA-producing autochthonous starters would allow the production of Cambodian fermented foods with an additional nutritional value that meet the population's dietary habits and that are also more attractive for the international food market. Matrix-assisted laser desorption/ionizing time-of-flight mass spectrometry (MALDI-TOF MS) and partial 16S rDNA sequencing were used to identify 68 LAB isolates from Cambodian fermented foods. These isolates were classified and grouped with (GTG)5 rep-PCR, resulting in 50 strains. Subsequently, all strains were investigated for their ability to produce GABA by thin layer chromatography. GABA-positive strains were further analyzed by the GABase assay. Of the six GABA-positive LAB strains-one Lactobacillus futsaii, two Lactobacillus namurensis, and three Lactobacillus plantarum strains-two Lactobacillus plantarum strains produced high amounts of GABA (20.34 mM, 16.47 mM). These strains should be further investigated for their potential application as GABA-producing starter cultures in the food applications.

Diversity of vaginal microbiome and metabolome during genital infections

We characterized the vaginal ecosystem during common infections of the female genital tract, as vulvovaginal candidiasis (VVC, n = 18) and Chlamydia trachomatis infection (CT, n = 20), recruiting healthy (HC, n = 21) and bacterial vaginosis-affected (BV, n = 20) women as references of eubiosis and dysbiosis. The profiles of the vaginal microbiome and metabolome were studied in 79 reproductive-aged women, by means of next generation sequencing and proton based-nuclear magnetic resonance spectroscopy. Lactobacillus genus was profoundly depleted in all the genital infections herein considered, and species-level analysis revealed that healthy vaginal microbiome was dominated by L. crispatus. In the shift from HC to CT, VVC, and BV, L. crispatus was progressively replaced by L. iners. CT infection and VVC, as well as BV condition, were mainly characterised by anaerobe genera, e.g. Gardnerella, Prevotella, Megasphaera, Roseburia and Atopobium. The changes in the bacterial communities occurring during the genital infections resulted in significant alterations in the vaginal metabolites composition, being the decrease of lactate a common marker of all the pathological conditions. In conclusion, according to the taxonomic and metabolomics analysis, we found that each of the four conditions is characterized by a peculiar vaginal microbiome/metabolome fingerprint.

In-vitro effect of vaginal lactobacilli against group B Streptococcus

Streptococcus agalactiae(GBS) is a leading cause of infection during pregnancy, preterm birth and neonatal infection, with a significant clinical and socio-economic impact. To prevent maternal GBS vaginal colonization, new antibiotic-free approaches, based on lactobacilli probiotics, are advisable. The aim of this study was to assess the anti-GBS activity of 14 vaginal Lactobacillus strains, belonging to different species (L. crispatus, L. gasseri, L. vaginalis), isolated from healthy pre-menopausal women. In particular, we performed 'inhibition' experiments, evaluating the ability of both Lactobacillus cells and culture supernatants in reducing Streptococcus viability, after 60 min contact time. First, we demonstrated that the acidic milieu, produced by vaginal lactobacilli metabolism, is crucial in counteracting GBS growth in a pH-dependent manner. Experiments with organic/inorganic acid solutions confirmed the strict correlation between pH levels and the anti-GBS activity. GBS was more sensitive to lactic acid than to hydrochloric acid, indicating that the presence of H⁺ ions is necessary but not sufficient for the inhibitory activity. Moreover, experiments with Lactobacillus pH-adjusted supernatants led to exclude a direct role in the anti-GBS activity by other bioactive molecules. Second, we found that only a few Lactobacillus strains were able to reduce Streptococcus viability by means of cell pellets. The anti-GBS effect displayed by Lactobacillus cells was related to the their ability to interact and aggregate with Streptococcus cells. We found that the anti-GBS activity was retained after methanol/proteinase K treatment, but lost after lysozyme exposure of Lactobacillus cells. Therefore, we supposed that non-proteinaceous components of Lactobacillus cell wall could be responsible for the anti-GBS activity. In conclusion, we identified specific Lactobacillus strains able to interfere with GBS viability by multiple strategies and we elucidated some of the mechanisms of action. These strains could serve as probiotic formulations for the prevention of GBS vaginal colonization.

Metabolic Characterization of Supernatants Produced by Lactobacillus spp. With in vitro Anti-Legionella Activity

Legionella pneumophila is an organism of public health interest for its presence in water supply systems and other humid thermal habitats. In this study, ten cell-free supernatants produced by Lactobacillus strains were evaluated for their ability to inhibit L. pneumophila strains isolated from hot tap water. Production of antimicrobial substances by Lactobacillus strains were assessed by agar well diffusion test on BCYE agar plates pre-inoculated with L. pneumophila. Cell-free supernatants (CFS) showed antimicrobial activity against all Legionella strains tested: L. rhamnosus and L. salivarius showed the highest activity. By means of a proton-based nuclear magnetic resonance (¹H-NMR) spectroscopy, we detected and quantified the Lactobacillus metabolites of these CFSs, so to gain information about which metabolic pathway was likely to be connected to the observed inhibition activity. A panel of metabolites with variations in concentration were revealed, but considerable differences among inter-species were not showed as reported in a similar work by Foschi et al. (2018). More than fifty molecules belonging mainly to the groups of amino acids, organic acids, monosaccharides, ketones, and alcohols were identified in the metabolome. Significant differences were recorded comparing the metabolites found in the supernatants of strains grown in MRS with glycerol and the same strains grown in MRS without supplements. Indeed, pathway analysis revealed that glycine, serine and threonine, pyruvate, and sulfur metabolic pathways had a higher impact when strains were grown in MRS medium with a supplement such as glycerol. Among the metabolites identified, many were amino acids, suggesting the possible presence of bacteriocins which could be linked to the anti-Legionella activity shown by cell-free supernatants.

Prospecting prebiotics, innovative evaluation methods, and their health applications: a review

Prebiotics are necessary natural and synthetic food ingredients that help in the growth and development of gut microflora. There is a complex relationship between gut dysbiosis and microbes, so alteration in both probiotics and prebiotics can reduce illness of gut, which further plays a decisive role in human health. The prebiotic efficiency can be validated using various in vitro and in vivo experiments, and this gives an important insight to this field. This review focuses on these aspects including the standardized assessment of prebiotics and its metabolic products for customary applications. This review has also summarized the mechanism of their beneficial actions such as immunomodulation, nutrient absorption, pathogen inhibition, etc., and its significance in human nutrition. In addition to this, some fascinating applications of prebiotics in health-related disorders have also discussed, with current challenges in this facet.

Liposomes containing biosurfactants isolated from Lactobacillus gasseri exert antibiofilm activity against methicillin resistant Staphylococcus aureus strains

Staphylococcus aureus is the major causative agent of skin and soft tissue infections, whose prevention and treatment have become more difficult due to the emergence of antibiotic-resistant strains. In this regard, the development of an effective treatment represents a challenge that can be overcome by delivering new antibiofilm agents with appropriate nanocarriers. In this study, a biosurfactant (BS) isolated from Lactobacillus gasseri BC9 and subsequently loaded in liposomes (LP), was evaluated for its ability to prevent the development and to eradicate the biofilm of different methicillin resistant S. aureus (MRSA) strains. BS from L. gasseri BC9 was not cytotoxic and was able to prevent formation and to eradicate the biofilm of different MRSA strains. BS loaded liposomes (BS-LP) presented a mean diameter (lower than 200 nm) suitable for topical administration and a low polydispersity index (lower than 0.2) that were maintained over time for up 28 days. Notably, BS-LP showed higher ability than free BS to inhibit S. aureus biofilm formation and eradication. BS-LP were loaded in lyophilized matrices able to quickly dissolve (dissolution time lower than 5 s) upon contact with exudate, thus allowing vesicle reconstitution. In conclusion, in this work, we demonstrated the antibiofilm activity of Lactobacillus-derived BS and BS-LP against clinically relevant MRSA strains. Furthermore, the affordable production of lyophilized matrices containing BS-LP for local prevention of cutaneous infections was established.

Properties of potentially probiotic Lactobacillus isolates from poultry intestines

The most commonly used probiotic bacteria belong to the genus Lactobacillus, being regarded as beneficial for poultry health and production. However, commercial probiotics do not always ensure both expected effects. In order to improve the utility properties of new preparations, the selection of new probiotic candidates should be made on the basis of the performance of the species within the poultry digestive tract. The aim of this study was to isolate and identify lactobacilli from poultry intestines, and to select probiotic candidates for subsequent in vivo trials. Digesta from 18 poultry specimens were collected, serially diluted, plated onto Wilkins-Chalgren anaerobe agar supplemented with 30% of rumen fluid and onto De Man, Rogosa and Sharpe agar plates, and incubated at 37 °C for 48 h under anaerobic conditions. Isolated colonies were subjected to Gram staining and catalase reaction. They were then pre-identified using matrix-assisted laser desorption ionization (MALDI) time of flight (TOF) mass spectrometry (MS). Forty-four Lactobacillus strains belonging to 16 species were identified and subjected to evaluations of survival under simulated gastrointestinal conditions, autoaggregation and hydrophobicity. Most of the screened Lactobacillus reuteri strains as well as individual strains of L. acidophilus, L. salivarius, L. saerimneri, and L. vaginalis showed high survival rates under gastrointestinal tract conditions and good surface properties. The results suggest their potential for further testing as probiotic candidates in in vivo trials.

Metabolomic analysis of significant changes in Lactobacillus casei Zhang during culturing to generation 4,000 under conditions of glucose restriction

Lactic acid bacteria are being consumed more frequently as awareness of their health benefits has increased. The industrial production of lactic acid bacteria requires a comprehensive understanding of their survival stress, especially regarding changes in metabolic substances in a glucose-limited environment. In the present study, a metabolomic approach was applied to investigate Lactobacillus casei Zhang using cultures from a common ancestor that were permitted to evolve under conditions with normal or glucose-restricted media for up to 4,000 generations. Metabolomic analyses of intracellular and extracellular differential metabolites under De Man, Rogosa and Sharpe broth (2% vol/vol glucose; Oxoid Ltd., Basingstoke, UK) and glucose-restricted (0.02% vol/vol glucose in De Man, Rogosa and Sharpe broth) conditions were performed at generations 0, 2,000, and 4,000 and revealed 23 different metabolites. Myristic acid, ergothioneine, Lys-Thr, and palmitamide contents exhibited significant reductions between 0 and 4,000 generations, whereas nicotinate, histidine, palmitic acid, l-lysine, urocanate, thymine, and other substances increased. The dynamics of the pathways involved in AA metabolism, including glycine, serine, and threonine metabolism, histidine metabolism, lysine degradation, and arginine and proline metabolism, were also a focus of the present study. There were also changes in several other metabolic pathways, including vitamin B₆, thiamine, nicotinate, and nicotinamide, according to generation time. Additionally, in the present study we screened for key metabolites involved in the glucose-restricted response and provided a theoretical basis for comprehensively revealing the regulatory mechanisms associated with L. casei Zhang glucose restriction at the metabolic level. These findings also provide novel ideas and methods for analyzing the glucose-restricted stress response at the metabolic level.

Univariate Statistical Analysis as a Guide to ¹H-NMR Spectra Signal Assignment by Visual Inspection

In Proton Nuclear Magnetic Resonance (¹H-NMR) spectroscopy, the signals assignment procedure is normally conducted by visual inspection of the spectra, by taking advantage of the innate predisposition of human eye for pattern recognition. In the case of untargeted metabolomics investigations on food and body fluids, the complexity of the spectra may lead the user to overlook signals, independently from their biological relevance. Here, we describe a four steps procedure that is designed to guide signals assignment task by visual inspection. The procedure can be employed whenever an experimental plan allows for the application of a univariate statistical analysis on a point-by-point basis, which is commonly the case. By comparing, as a proof of concept, ¹H-NMR spectra of vaginal fluids of healthy and bacterial vaginosis (BV) affected women, we show that the procedure is also readily usable by non-experts in three particularly challenging cases: overlapping multiplets, poorly aligned signals, and signals with very poor signal-to-noise ratio. The paper is accompanied by the necessary codes and examples written in R computational language to allow the interested user gaining a hands-on impression of the procedure’s strengths and weaknesses.

Diet, Microbiota, and Gut Permeability-The Unknown Triad in Rheumatoid Arthritis

Growing experimental and clinical evidence suggests that a chronic inflammatory response induced by gut dysbiosis can critically contribute to the development of rheumatic diseases, including rheumatoid arthritis (RA). Of interest, an adherence to a Mediterranean diet has been linked to a reduction in mortality and morbidity in patients with inflammatory diseases. Diet and intestinal microbiota are modifying factors that may influence intestinal barrier strength, functional integrity, and permeability regulation. Intestinal microbiota may play a crucial role in RA pathogenesis, but up to now no solid data has clarified a mechanistic relationship between gut microbiota and the development of RA. Nonetheless, microbiota composition in subjects with RA differs from that of controls and this altered microbiome can be partially restored after prescribing disease modifying antirheumatic drugs. High levels of Prevotella copri and similar species are correlated with low levels of microbiota previously associated with immune regulating properties. In addition, some nutrients can alter intestinal permeability and thereby influence the immune response without a known impact on the microbiota. However, critical questions remain to be elucidated, such as the way microbiome fluctuates in relation to diet, and how disease activity may be influenced by changes in diet, microbiota or diet-intestinal microbiota equilibrium.

Impact of meropenem on Klebsiella pneumoniae metabolism

The aim of this study was to analyze the metabolome of several Klebsiella pneumoniae strains characterized by different resistance patterns. A total of 59 bacterial strains (27 carbapenemase-negative and 32 carbapenemase-positive) were included and their metabolic features were assessed in basal conditions. Moreover, 8 isolates (4 wild-type and 4 KPC-producers) were randomly selected to evaluate the impact of sub-lethal concentrations of meropenem on bacterial metabolism. The metabolomic analysis was performed by ¹H-NMR spectroscopy both on filtered supernatants and cell lysates. A total of 40 and 20 molecules were quantified in the intracellular and the extracellular metabolome, respectively. While in basal conditions only five metabolites showed significant differences between carbapenemase-positive and negative strains, the use of meropenem had a profound impact on the whole bacterial metabolism. In the intracellular compartment, a reduction of different overflow metabolites and organic acids (e.g. formate, acetate, isobutyrate) was noticed, whereas, in the extracellular metabolome, the levels of several organic acids (e.g. succinate, acetate, formate, lactate) and amino acids (aspartate, threonine, lysine, alanine) were modified by meropenem stimulation. Interestingly, carbapenemase-positive and negative strains reacted differently to meropenem in terms of number and type of perturbed metabolites. In wild-type strains, meropenem had great impact on the metabolic pathways related to methane metabolism and alanine, aspartate and glutamate metabolism, whereas in KPC-producers the effect was predominant on pyruvate metabolism. The knowledge about the bacterial metabolic profiles could help to set up innovative diagnostic methods and new antimicrobial strategies to fight the global crisis against carbapenemase-positive K. pneumoniae.

Dietary Lactobacillus acidophilus positively influences growth performance, gut morphology, and gut microbiology in rurally reared chickens

In a market undergoing constant evolution, the production of chicken meat that consumers would perceive as “natural” and “animal friendly” is crucial. The use of probiotics in rurally reared chickens could represent a major opportunity to achieve mutual benefit for both the industry and consumers. A total of 264 male Kabir chicks were randomly distributed to one of 2 dietary treatments: the L group received a commercial feed supplemented with 2.0 g/100 kg of Lactobacillus acidophilus D2/CSL, while the C group received the same basal diet without the additive. To assess the effects of probiotic supplementation in the chickens’ diet, productive performance was evaluated at d 21 and 42, whereas microbiological analyses of the intestinal content and intestinal histology and morphometry were performed at the end of the trial (d 42). At d 21 and 42, L birds showed better (P < 0.001) performance in terms of body weight, average daily gain, and feed conversion ratio. Enterococci, staphylococci, and Escherichia coli populations were not influenced by dietary treatment. On the contrary, Lactobacillus population increased (P = 0.032) in the L group. Furthermore, a tendency (P = 0.069) was observed for the coliforms to be influenced by diet, with lower values in the L group in comparison to the C group. Histological techniques revealed that the number of goblet cell containing neutral mucins was lower in the C group. Morphometric evaluations demonstrated that the probiotic supplementation increased the height of the mucosal layer by improving (P = 0.040) villus height, while crypt depth was unaffected. In conclusion, the results obtained in this study demonstrate that it is possible to use Lactobacillus acidophilus D2/CSL (CECT 4529) in rurally reared chicken breeds with positive effects on performance and gut health.

Using glycolysis enzyme sequences to inform Lactobacillus phylogeny

The genus Lactobacillus encompasses a diversity of species that occur widely in nature and encode a plethora of metabolic pathways reflecting their adaptation to various ecological niches, including humans, animals, plants and food products. Accordingly, their functional attributes have been exploited industrially and several strains are commonly formulated as probiotics or starter cultures in the food industry. Although divergent evolutionary processes have yielded the acquisition and evolution of specialized functionalities, all Lactobacillus species share a small set of core metabolic properties, including the glycolysis pathway. Thus, the sequences of glycolytic enzymes afford a means to establish phylogenetic groups with the potential to discern species that are too closely related from a 16S rRNA standpoint. Here, we identified and extracted glycolysis enzyme sequences from 52 species, and carried out individual and concatenated phylogenetic analyses. We show that a glycolysis-based phylogenetic tree can robustly segregate lactobacilli into distinct clusters and discern very closely related species. We also compare and contrast evolutionary patterns with genome-wide features and transcriptomic patterns, reflecting genomic drift trends. Overall, results suggest that glycolytic enzymes provide valuable phylogenetic insights and may constitute practical targets for evolutionary studies.

Insights Into Vaginal Bacterial Communities and Metabolic Profiles of Chlamydia trachomatis Infection: Positioning Between Eubiosis and Dysbiosis

The vaginal microbiota plays a crucial role in maintaining the health and functioning of the female genital tract, preventing the colonization of urogenital pathogens and sexually transmitted infections. In this study, we characterized the vaginal bacterial communities and the metabolome associated to Chlamydia trachomatis infection (CT: 20 women), compared to healthy condition (H: 22 women) and bacterial vaginosis (BV: 19 women). A microarray-based tool (VaginArray), implemented with a real-time PCR for Gardnerella vaginalis, was used to determine the vaginal bacterial composition, whereas the metabolic profiles were assessed by a proton-based nuclear magnetic resonance (¹H-NMR) spectroscopy. CT infection was characterized by bacterial and metabolic signatures similar to healthy condition, even though higher amounts of Lactobacillus iners, as well as depletion of some amino acids, biogenic amines, and succinate marked CT infection. Moreover, the frequency of Lactobacillus crispatus was higher in asymptomatic CT-positive patients than in women with CT-correlated symptoms. We also confirmed the marked differences in the microbiome and metabolome between healthy and BV-affected women. In conclusion, we highlighted microbial and metabolic peculiarities of the vaginal ecosystem in the case of CT infection, even though further studies are needed to understand if the observed alterations precede the infection onset or if the pathogen itself perturbs the vaginal environment.

Vaginal Lactobacilli Reduce Neisseria gonorrhoeae Viability through Multiple Strategies: An in Vitro Study

The emergence and spread of antimicrobial resistance in Neisseria gonorrhoeae (GC) underline the need of “antibiotic-free” strategies for the control of gonorrhea. The aim of this study was to assess the anti-gonococcal activity of 14 vaginal Lactobacillus strains, belonging to different species (L. crispatus, L. gasseri, L. vaginalis), isolated from healthy pre-menopausal women. In particular, we performed “inhibition” experiments, evaluating the ability of both lactobacilli cells and culture supernatants in reducing GC viability, at two different contact times (7 and 60 min). First, we found that the acidic environment, associated to lactobacilli metabolism, is extremely effective in counteracting GC growth, in a pH- and time-dependent manner. Indeed, a complete abolishment of GC viability by lactobacilli supernatants was observed only for pH values < 4.0, even at short contact times. On the contrary, for higher pH values, no 100%-reduction of GC growth was reached at any contact time. Experiments with organic/inorganic acid solutions confirmed the strict correlation between the pH levels and the anti-gonococcal effect. In this context, the presence of lactate seemed to be crucial for the anti-gonococcal activity, especially for pH values in the range 4.4–5.3, indicating that the presence of H⁺ ions is necessary but not sufficient to kill gonococci. Moreover, experiments with buffered supernatants led to exclude a direct role in the GC killing by other bioactive molecules produced by lactobacilli. Second, we noticed that lactobacilli cells are able to reduce GC viability and to co-aggregate with gonococci. In this context, we demonstrated that released-surface components with biosurfactant properties, isolated from “highly-aggregating” lactobacilli, could affect GC viability. The antimicrobial potential of biosurfactants isolated from lactobacilli against pathogens has been largely investigated, but this is the first report about a possible use of these molecules in order to counteract GC infectivity. In conclusion, we identified specific Lactobacillus strains, mainly belonging to L. crispatus species, able to counteract GC viability through multiple mechanisms. These L. crispatus strains could represent a new potential probiotic strategy for the prevention of GC infections in women.