Antimicrobial activity of Lactobacillus fermentum TcUESC01 against Streptococcus mutans UA159

Antagonistic activity of Lactobacillus spp. and Bifidobacterium spp. against cariogenic Streptococcus mutans in vitro and viability when added to chewing gum during storage

The aim of the work was to evaluate antagonistic activity of Lactobacillus spp. and Bifidobacterium spp. in vitro against cariogenic Streptococcus mutans UA 159 and viability in chewing gum, during storage. Antagonistic activity was evaluated in vitro by the "spot on the lawn" test. Two bacteria were chosen and subjected to lyophilization and microencapsulation using the atomization method, containing polyvinylpyrrolidone polymer and lactose as encapsulating agents. For application in food matrices, four treatments were elaborated: chewing gum containing lyophilized B. lactis B94 (BLL), microencapsulated B. lactis B94 (BLE), lyophilized L. brevis (LBL), and microencapsulated L. brevis (LBE). Both microorganisms demonstrated a high capacity for inhibition against S. mutans, when compared to oral antiseptic chlorhexidine 0.2% in vitro, and according to the test of sensitivity profile to proteolytic enzymes, all the bacteria tested are producers of antimicrobial peptides, resulting in the inhibitory activity of the cariogenic bacterium. Furthermore, the viability of B. lactis B94 and L. brevis was maintained after microencapsulation, indicating that the process was efficient, with no significant difference (p < 0.05) between the results. And, in the chewing gum containing the bacteria during the storage period (33 days), it was found that cell immobilization did not significantly influence (p < 0.05) the counts of L. brevis but benefited the viability of B. lactis B94. Therefore, both probiotic bacteria are producers of antimicrobial substances with the ability to inhibit S. mutans, in vitro. The microencapsulation was considered efficient since it influenced the viability of B. lactis B94 (> 8 log CFU/g); however, the microencapsulation did not influence the viability of L. brevis since in both lyophilized and encapsulated form; the concentration of the bacteria remained above 8 log CFU/g during the storage period of the chewing gum.

Glycogen availability and pH variation in a medium simulating vaginal fluid influence the growth of vaginal Lactobacillus species and Gardnerella vaginalis

BACKGROUND

Glycogen metabolism by Lactobacillus spp. that dominate the healthy vaginal microbiome contributes to a low vaginal pH (3.5-4.5). During bacterial vaginosis (BV), strict and facultative anaerobes including Gardnerella vaginalis become predominant, leading to an increase in the vaginal pH (> 4.5). BV enhances the risk of obstetrical complications, acquisition of sexually transmitted infections, and cervical cancer. Factors critical for the maintenance of the healthy vaginal microbiome or the transition to the BV microbiome are not well defined. Vaginal pH may affect glycogen metabolism by the vaginal microflora, thus influencing the shift in the vaginal microbiome.

RESULTS

The medium simulating vaginal fluid (MSVF) supported growth of L. jensenii 62G, L. gasseri 63 AM, and L. crispatus JV-V01, and G. vaginalis JCP8151A at specific initial pH conditions for 30 d. L. jensenii at all three starting pH levels (pH 4.0, 4.5, and 5.0), G. vaginalis at pH 4.5 and 5.0, and L. gasseri at pH 5.0 exhibited the long-term stationary phase when grown in MSVF. L. gasseri at pH 4.5 and L. crispatus at pH 5.0 displayed an extended lag phase over 30 d suggesting inefficient glycogen metabolism. Glycogen was essential for the growth of L. jensenii, L. crispatus, and G. vaginalis; only L. gasseri was able to survive in MSVF without glycogen, and only at pH 5.0, where it used glucose. All four species were able to survive for 15 d in MSVF with half the glycogen content but only at specific starting pH levels - pH 4.5 and 5.0 for L. jensenii, L. gasseri, and G. vaginalis and pH 5.0 for L. crispatus.

CONCLUSIONS

These results suggest that variations in the vaginal pH critically influence the colonization of the vaginal tract by lactobacilli and G. vaginalis JCP8151A by affecting their ability to metabolize glycogen. Further, we found that L. jensenii 62G is capable of glycogen metabolism over a broader pH range (4.0-5.0) while L. crispatus JV-V01 glycogen utilization is pH sensitive (only functional at pH 5.0). Finally, our results showed that G. vaginalis JCP8151A can colonize the vaginal tract for an extended period as long as the pH remains at 4.5 or above.

In Vitro Selection of Lactobacillus and Bifidobacterium Probiotic Strains for the Management of Oral Pathobiont Infections Associated to Systemic Diseases

The human oral pathobionts Aggregatibacter actinomycetemcomitans, Streptococcus mitis and Streptococcus mutans, in dysbiosis-promoting conditions, lead to oral infections, which also represent a threat to human systemic health. This scenario may be worsened by antibiotic misuse, which favours multi-drug resistance, making the research on pathogen containment strategies more than crucial. Therefore, we aimed to in vitro select the most promising probiotic strains against oral pathogen growth, viability, biofilm formation, and co-aggregation capacity, employing both the viable probiotics and their cell-free supernatants (CFSs). Interestingly, we also assessed probiotic efficacy against the three-pathogen co-culture, mimicking an environment similar to that in vivo. Overall, the results showed that Lactobacillus CFSs performed better than the Bifidobacterium, highlighting Limosilactobacillus reuteri LRE11, Lacticaseibacillus rhamnosus LR04, Lacticaseibacillus casei LC04, and Limosilactobacillus fermentum LF26 as the most effective strains, opening the chance to deeper investigation of their action and CFS composition. Altogether, the methodologies presented in this study can be used for probiotic efficacy screenings, in order to better focus the research on a viable probiotic, or on its postbiotics, suitable in case of infections.

Assessing the cytotoxic effect and antimicrobial activity of Moringa oleifera aqueous and ethanolic extract against oral pathogens extracted from periodontal and orthodontic patients

Background: Periodontitis is the result of inflammation caused due to the activity of microorganisms. The prevalence of anaerobic organisms is more when it comes to periodontal pockets and orthodontic patients. Plants with phytochemicals that could exert antimicrobial effects could aid in host modulation for management of periodontitis caused by these bacteria in periodontal and orthodontic patients Aim: To assess the antimicrobial effect of aqueous extract of Moringa oleifera Lam (MOL) and cytotoxic effect of aqueous and ethanol extracts of MOL. Materials and methods: Moringa oleifera Lam. extracts were prepared by maceration. Subgingival plaque samples were collected and microorganisms were cultured in anaerobic environment. The microorganisms were treated with the extracts and minimum inhibitory concentration and minimum bactericidal concentration was assessed. The cytotoxic effects were assessed by brine shrimp assay. Results: Aqueous extract showed antimicrobial effect in dose and time dependent manner and both extracts exhibited cytotoxic effects in a dose and time dependent manner Summary and Conclusion: The antimicrobial effect of MOL could be utilized to develop a nature derived local drug delivery system for treating plaque induced periodontitis in different clinical situations.

Chitosan-Sodium Caseinate Composite Edible Film Incorporated with Probiotic Limosilactobacillus fermentum: Physical Properties, Viability, and Antibacterial Properties

Single-use synthetic plastics that are used as food packaging is one of the major contributors to environmental pollution. Hence, this study aimed to develop a biodegradable edible film incorporated with Limosilactobacillus fermentum. Investigation of the physical and mechanical properties of chitosan (CS), sodium caseinate (NaCas), and chitosan/sodium caseinate (CS/NaCas) composite films allowed us to determine that CS/NaCas composite films displayed higher opacity (7.40 A/mm), lower water solubility (27.6%), and higher Young's modulus (0.27 MPa) compared with pure CS and NaCas films. Therefore, Lb. fermentum bacteria were only incorporated in CS/NaCas composite films. Comparison of the physical and mechanical properties of CS/NaCas composite films incorporated with bacteria with those of control CS/NaCas composite films allowed us to observe that they were not affected by the addition of probiotics, except for the flexibility of films, which was improved. The Lb. fermentum incorporated composite films had a 0.11 mm thickness, 17.9% moisture content, 30.8% water solubility, 8.69 A/mm opacity, 25 MPa tensile strength, and 88.80% elongation at break. The viability of Lb. fermentum after drying the films and the antibacterial properties of films against Escherichia coli O157:H7 and Staphylococcus aureus ATCC 29213 were also evaluated after the addition of Lb. fermentum in the composite films. Dried Lb. fermentum composite films with 6.65 log₁₀ CFU/g showed an inhibitory effect against E. coli and S. aureus (0.67 mm and 0.80 mm inhibition zone diameters, respectively). This shows that the Lb.-fermentum-incorporated CS/NaCas composite film is a potential bioactive packaging material for perishable food product preservation.

Characterization, High-Density Fermentation, and the Production of a Directed Vat Set Starter of Lactobacilli Used in the Food Industry: A Review

Lactobacilli have been widely concerned for decades. Bacteria of the genus Lactobacillus have been commonly employed in fermented food to improve the appearance, smell, and taste of food or prolong its shelf-life. They comprise 261 species (by March 2020) that are highly diverse at the phenotypic, ecological, and genotypic levels. Some Lactobacilli strains have been documented to be essential probiotics, which are defined as a group of living microorganisms that are beneficial to the health of the host when ingested in sufficiency. However, the characterization, high-density fermentation, and the production of a directed vat set (DVS) starter of Lactobacilli strains used in the food industry have not been systematically reported. This paper mainly focuses on reviewing Lactobacilli as functional starter cultures in the food industry, including different molecular techniques for identification at the species and strain levels, methods for evaluating Lactobacilli properties, enhancing their performance and improving the cell density of Lactobacilli, and the production techniques of DVS starter of Lactobacilli strains. Moreover, this review further discussed the existing problems and future development prospects of Lactobacilli in the food industry. The viability and stability of Lactobacilli in the food industry and gastrointestinal environment are critical challenges at the industrial scale. The new production equipment and technology of DVS starter of Lactobacilli strains will have the potential for large-scale application, for example, developing low-temperature spray drying, freezing granulation drying, and spray freeze-drying.

Cervicovaginal microbiota isolated from healthy women exhibit probiotic properties and antimicrobial activity against pathogens isolated from cervical cancer patients

Abnormal cervicovaginal microbiota play an important role in HPV persistence and progression to cervical cancer. The present study aimed at isolating and identifying potential probiotics from vaginal swabs of healthy women and evaluating their activity against vaginal pathogens isolated from cervical cancer patients. Based on probiotic, acid-bile tolerance and antimicrobial properties, 13 lactic acid bacteria (LAB) from the healthy group were identified by MALDI TOF MS (Matrix Assisted Laser Desorption and Ionisation, Time Of Flight Mass Spectrometry). Among these, four strains, Lactobacillus gasseri P36Mops, Limosilactobacillus fermentum P37Mws, Lactobacillus delbrueckii P31Mcs and Enterococcus faecium P26Mcm, exhibited significant antimicrobial activity against 8 vaginal pathogens (Staphylococcus haemolyticus P41Tcs, Escherichia coli P30Tcs, E. coli P79Bcm, Enterococus faecalis P29Mops, E. faecalis P50Tws, E. faecalis P68Tcb, S. haemolyticus P48Bcb and S. haemolyticus P58Bcb) isolated from precancerous and cervical cancer patients. 16S rRNA sequencing of four potential probiotics revealed congruency with the MALDI-TOF MS identification and phylogenetic analysis showed genetic relationship with previously reported LAB strains. The selected LAB showed strain specific hydrophobicity (35.88-56.70%), auto-aggregation (35.26-61.39%) and antibiotic susceptibility. Interestingly, L. gasseri P36Mops was resistant to five standard antibiotics routinely used against urogenital or vaginal infections. LCMS (Liquid Chromatography Mass Spectrometry) analyses of the CFS (cell-free supernatant) of the four potential probiotics revealed the presence of metabolites such as N-(1-deoxy-1-fructosyl)valine, hygroline, acetoxy-2-hydroxy-16-heptadecen-4-one, avocadyne 4-acetate, avocadyne 2-acetate, taraxinic acid glucosyl ester, 6-hydroxypentadecanedioic acid, with reported antimicrobial activity. The overall data suggest the bio-therapeutic potential of the identified vaginal probiotics against cervical cancer-associated pathogens.

Limosilactobacillus fermentum from buffalo milk is suitable for potential biotechnological process development and inhibits Helicobacter pylori in a gastric epithelial cell model

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L.fermentum from buffalo milk grows efficiently without animal-derived medium components.

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Highest viable biomass titers can be reached after only 8h improving productivity.

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L. fermentum is suitable for large scale production: complete biotech approach.

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L. fermentum demonstrates 60% cell survival after spray drying.

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L. fermentum from buffalo milk displaces H. pylori in a gastric epithelial cell model.

Probiotics are living microorganisms that give beneficial health effects while consumed, and each strain possesses diverse and unique properties and also different technological characteristics that affect its ability to be produced at large scale. Limosilactobacillus fermentum is a widely studied member of probiotics, however, few data are available on the development of fermentation and downstream processes for the production of viable biomasses for potential industrial applications.

In the present study a novel L. fermentum strain was isolated from buffalo milk and used as test example for biotechnological process development. The strain was able to produce up to 10⁹ CFU/mL on a (glucose based) semi-defined medium deprived of animal-derived raw materials up to the pilot scale (150 L), demonstrating improved results compared to commonly used, although industrially not suitable, media rich of casein and beef extract. The study of strain behavior in batch experiments indicated that the highest concentration of viable cells was reached after only 8 h of growth, greatly shortening the process. Moreover, initial concentrations of glucose in the medium above 30 g/L, if not supported by higher nitrogen concentrations, reduced the yield of biomass and increased production of heterolactic fermentation by-products. Biomass concentration via microfiltration on hollow fibers, and subsequent spray-drying allowed to recover about 5.7 × 10¹⁰CFU/g_powder of viable cells, indicating strain resistance to harsh processing conditions.

Overall, these data demonstrate the possibility to obtain and maintain adequate levels of viable L. fermentum cells by using a simple approach that is potentially suitable for industrial development. Moreover, since often exopolysaccharides produced by lactobacilli contribute to the strain's functionality, a partial characterization of the EPS produced by the newly identified L. fermentum strain was carried out.

Finally, the effect of L. fermentum versus H. pylori in a gastric epithelial cell model was evaluated demonstrating its ability to stimulate the response of the immune system and displace the infective agent.

New dimer and trimer of chalcone derivatives from anti-inflammatory and antinociceptive extracts of Schinopsis brasiliensis roots

ETHNOPHARMACOLOGY RELEVANCE

Schinopsis brasiliensis Engl. is an endemic tree of the Brazilian semi-arid regions belonging to the Anacardiaceae family. It is the main representative of the genus Schinopsis, mostly native to Brazil and popularly known as "braúna" or "baraúna". Different parts of this plant are employed in Brazilian folk medicines to treat inflammation in general, sexual impotence, cough, and influenza.

AIM OF THE STUDY

This work describes the antinociceptive (acetic acid-induced writhing and formalin-induced nociception) and anti-inflammatory (paw edema and neutrophil migration) activities of the extract of the root of S. brasiliensis. Besides, the evaluation of total phenolic compounds and antioxidant, antimicrobial (including MRSA bacteria), and acetylcholinesterase inhibition activities were also determined.

MATERIAL AND METHODS

The pure compounds were isolated by different chromatographic techniques and their chemical structures have been unambiguously elucidated based on extensive spectroscopic methods, including 1D (¹H, ¹³C, DEPT, and NOEdiff) and 2D (HSQC, HMBC, and NOESY) NMR experiments, MS data, and comparison with the literature data of similar compounds. The antinociceptive and anti-inflammatory activities were evaluated by acid acetic writhing test, formalin paw edema, and by the investigation of neutrophil migration to the peritoneal cavities of mice. For antimicrobial evaluation were determined MIC and MBC, antioxidant activities were obtained by TPC and DPPH tests, and AChE inhibition by Elmann's methodology.

RESULTS

The extracts showed antinociceptive and anti-inflammatory activities and two unusual new compounds, a cyclobutanyl chalcone trimer (schinopsone A) and a cyclohexene-containing chalcone dimer (schinopsone B), with six known compounds were isolated from the active extracts. Additionally, the acetylcholinesterase inhibitory activity for isolated compounds was reported for the first time in this study. Molecular docking studies indicated that the isolated compounds are responsible for the interaction with anti-inflammatory targets (COX 1 and 2 and LOX) with variable binding affinities, indicating a possible mechanism of action of these compounds.

CONCLUSIONS

These findings indicate for the first time the correlation between the anti-inflammatory activity different enriched polyphenol-organic soluble fractions of S. brasiliensis, and it contributes to the understanding of the anti-inflammatory potential of S. brasiliensis.

Assessing the drug resistance profiles of oral probiotic lozenges

Background

Probiotic lozenges have been developed to harvest the benefits of probiotics for oral health, but their long-term consumption may encourage the transfer of resistance genes from probiotics to commensals, and eventually to disease-causing bacteria.

Aim

To screen commercial probiotic lozenges for resistance to antibiotics, characterize the resistance determinants, and examine their transferability in vitro.

Results

Probiotics of all lozenges were resistant to glycopeptide, sulfonamide, and penicillin antibiotics, while some were resistant to aminoglycosides and cephalosporins. High minimum inhibitory concentrations (MICs) were detected for streptomycin (>128 µg/mL) and chloramphenicol (> 512 µg/mL) for all probiotics but only one was resistant to piperacillin (MIC = 32 µg/mL). PCR analysis detected erythromycin (erm(T), ermB or mefA) and fluoroquinolone (parC or gyr(A)) resistance genes in some lozenges although there were no resistant phenotypes. The dfrD, cat-TC, vatE, aadE, vanX, and aph(3")-III or ant(2")-I genes conferring resistance to trimethoprim, chloramphenicol, quinupristin/dalfopristin, vancomycin, and streptomycin, respectively, were detected in resistant probiotics. The rifampicin resistance gene rpoB was also present. We found no conjugal transfer of streptomycin resistance genes in our co-incubation experiments.

Conclusion

Our study represents the first antibiotic resistance profiling of probiotics from oral lozenges, thus highlighting the health risk especially in the prevailing threat of drug resistance globally.

Different Concentrations of Lactobacillus acidophilus Cell Free Filtrate Have Differing Anti-Biofilm and Immunomodulatory Effects

Probiotics such as various strains of Lactobacillaceae have been shown to have antimicrobial and immunomodulatory activity. In vitro studies have shown that Lactobacilli can decrease bacterial biofilm formation. Effects on immune cells have been unclear with most studies showing anti-inflammatory activity. The mechanism of effects has not been clearly elucidated. In these studies, we used different concentrations of live Lactobacillus acidophilus as well as cell free filtrate (CFF) derived from different concentrations of bacteria. Use of CFF is advantageous as a therapeutic because in vivo it can directly contact immune cells and its concentration is fixed. Both live cells and CFF inhibited Pseudomonas aeruginosa biofilm formation. Importantly, we show that high concentration CFF destroyed mature biofilm. This activity was not due to a lowered pH per se, as pH matched HCl did not remove mature biofilm. High concentration CFF totally inhibited P. aeruginosa growth and was bactericidal (>99.99%), but low concentration CFF was not bactericidal. To examine the immunomodulatory effects of L. acidophilus, we incubated THP-1 monocytes and derived macrophages with CFF and measured TNFα production. CFF did not significantly increase TNFα production in THP-1 monocytes. When cells were prestimulated with LPS, high concentration CFF increased TNFα production even further. In macrophages, high concentration CFF alone increased TNFα production but did not affect LPS prestimulated cells. In contrast, low concentration CFF decreased TNFα production in LPS prestimulated cells. To elucidate the possible mechanisms for these effects, we repeated the experiments using a NF-κB reporter THP-1 cell line. High concentration CFF increased NF-κB activity in monocytes and macrophages. In LPS prestimulated macrophages, only low concentration CFF reduced NF-κB activity. These results suggest that high concentration CFF alone induced NF-κB expression which could account partially for an increase in TNFα production. On the other hand, in macrophages, the lower non-bactericidal concentration of CFF reduced NF-κB expression and decreased TNFα production after LPS prestimulation. Taken together, the results provide evidence that different concentrations of L. acidophilus CFF possess varying bactericidal, anti-biofilm and immunomodulatory effects. This is important in vivo to evaluate the possible use of L. acidophilus CFF in different conditions.

Effect of Novel Bacteriocinogenic Lactobacillus fermentum BZ532 on Microbiological Shelf-Life and Physicochemical and Organoleptic Properties of Fresh Home-Made Bozai

Bacteriocinogenic Lactobacillus fermentum BZ532 with novel bacteriocin LF-BZ532 was originally isolated from Chinese cereal fermented drink, showing an antimicrobial characteristic during fermentation. This study aimed to explore the in situ antimicrobial activities of L. fermentum BZ532 and co-culturing investigation against key food pathogens, i.e., Staphylococcus aureus and Escherichia coli K-12, was conducted during fresh bozai production. The growth of spoilage bacteria was suppressed and bacterial count was reduced to a significantly low level during 48 h of co-cultures. In situ production of antimicrobial compounds expressed positive activity against S. aureus and E. coli K-12, but negative acitivity against Salmonella sp. D104. The total viable count of bozai BZ-Lf (bozai fermented with BZ532 strain) had a comparatively lower viable count than bozai BZ-C (bozai as an experimental control without BZ532) during storage of 7 days. Titratable acidity of bozai treatments (BZ-C, BZ-Lf) was increased, while pH declined accordingly during storage of 7 days. The organoleptic quality of bozai BZ-C had low sensorial scores as compared with BZ-Lf during storage. In comparison with naturally fermented bozai (BZ-C), L. fermentum BZ532 (BZ-Lf) could significantly reduce the microbial spoilage and extend the shelf-life based on microbiological examination. Conclusively, L. fermentum BZ532 can be used as a bio-protective culture for improving the safety of bozai.

Lactobacillus plantarum Lp62 exerts probiotic effects against Gardnerella vaginalis ATCC 49154 in bacterial vaginosis

The severe side-effects elicited by conventional antibiotic therapy and the recurrence of Bacterial vaginosis-associated bacteria and bacterial resistance have led to the development of novel alternative therapies, among which genital probiotics are widely used. In this study, we aimed to evaluate the antimicrobial activities of Lactobacillus plantarum Lp62 and its supernatant against Gardnerella vaginalis, using both in vitro and in vivo approaches. In vitro assays were used to evaluate the viability of the strain and the antimicrobial activities of the supernatant in different pH ranges. An in vivo assay was performed on female BALB/c mice, wherein the animals were divided into eight groups: four control groups and four treated groups (for curative and preventive therapies). After infecting and treating the mice, the animals were killed to quantify the bacterial load using qPCR, evaluate leucocyte cellular response, determine vaginal cytokine levels and perform cytokine tissue gene expression. Our analyses revealed significant activity of the strain and its supernatant against G. vaginalis. Preliminary in vitro tests showed that the strain grew with equal efficiency in different pH ranges. Meanwhile, the presence of halo and inhibition of pathogen growth established the significant activity of the supernatant against G. vaginalis. We observed that both micro-organisms are resident bacteria of mouse microbiota and that the lactobacilli population growth was affected by G. vaginalis and vice versa. We also observed that the treated groups, with their low bacterial load, absence of leucocyte recruitment, reduced cytokine levels in the vaginal lavage and normalized cytokine gene expression, successfully controlled the infection.

Lactiplantibacillus plantarum strains isolated from spontaneously fermented cocoa exhibit potential probiotic properties against Gardnerella vaginalis and Neisseria gonorrhoeae

Background

Probiotics are important tools in therapies against vaginal infections and can assist traditional antibiotic therapies in restoring healthy microbiota. Recent research has shown that microorganisms belonging to the genus Lactobacillus have probiotic potential. Thus, this study evaluated the potential in vitro probiotic properties of three strains of Lactiplantibacillus plantarum, isolated during the fermentation of high-quality cocoa, against Gardnerella vaginalis and Neisseria gonorrhoeae. Strains were evaluated for their physiological, safety, and antimicrobial characteristics.

Results

The hydrophobicity of L. plantarum strains varied from 26.67 to 91.67%, and their autoaggregation varied from 18.10 to 30.64%. The co-aggregation of L. plantarum strains with G. vaginalis ranged from 14.73 to 16.31%, and from 29.14 to 45.76% with N. gonorrhoeae. All L. plantarum strains could moderately or strongly produce biofilms. L. plantarum strains did not show haemolytic activity and were generally sensitive to the tested antimicrobials. All lactobacillus strains were tolerant to heat and pH resistance tests. All three strains of L. plantarum showed antimicrobial activity against the tested pathogens. The coincubation of L. plantarum strains with pathogens showed that the culture pH remained below 4.5 after 24 h. All cell-free culture supernatants (CFCS) demonstrated activity against the two pathogens tested, and all L. plantarum strains produced hydrogen peroxide. CFCS characterisation in conjunction with gas chromatography revealed that organic acids, especially lactic acid, were responsible for the antimicrobial activity against the pathogens evaluated.

Conclusion

The three strains of L. plantarum presented significant probiotic characteristics against the two pathogens of clinical importance. In vitro screening identified strong probiotic candidates for in vivo studies for the treatment of vaginal infections.

Anticariogenic activities of Libidibia ferrea, gallic acid and ethyl gallate against Streptococcus mutans in biofilm model

ETHNOPHARMACOLOGICAL RELEVANCE

In Brazil, ethnopharmacological studies show that Libidibia ferrea (Mart. ex Tul.) L. P. Queiroz is commonly used in folk medicine as an antifungal, antimicrobial and anti-inflammatory. In the Amazon region, the dried fruit powder of L. ferrea are widely used empirically by the population in an alcoholic tincture as an antimicrobial mouthwash in oral infections and the infusion is also recommended for healing oral wounds. However, there are few articles that have evaluated the antimicrobial activity against oral pathogens in a biofilm model, identifying active compounds and mechanisms of action.

AIM OF THE STUDY

The aim of this study was to evaluate the antimicrobial and anti-adherence activities of the ethanolic extract, fractions and isolated compounds (gallic acid and ethyl gallate) of the fruit and seed of L. ferrea against Streptococcus mutans. The inhibition of acidicity/acidogenicity and the expression of the S. mutans GTF genes in biofilms were also evaluated.

MATERIALS AND METHODS

Minimal Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Minimum Inhibitory Concentration of Cell Adhesion (MICA) were evaluated with ethanolic extract (EELF), fractions, gallic acid (GA) and ethyl gallate (EG) against S. mutans. Inhibition of biofilm formation, pH drop and proton permeability tests were conducted with EELF, GA and EG, and also evaluated the expression of the GTF genes in biofilms. The compounds of dichloromethane fraction were identified by GC-MS.

RESULTS

This is the first report of shikimic, pyroglutamic, malic and protocatechuic acids identified in L. ferrea. EELF, GA and EG showed MIC at 250 μg/mL, and MBC at 1000 μg/mL by EELF. EELF biofilms showed reduced dry weight and acidogenicity of S. mutans in biofilms. GA and EG reduced viable cells, glucans soluble in alkali, acidogenicity, aciduricity and downregulated expression of gtfB, gtfC and gtfD genes in biofilms. SEM images of GA and EG biofilms showed a reduction of biomass, exopolysaccharide and microcolonies of S. mutans.

CONCLUSIONS

The ethanolic extract of fruit and seed of L. ferrea, gallic acid and ethyl gallate showed great antimicrobial activity and inhibition of adhesion, reduction of acidogenicity and aciduricity in S. mutans biofilms. The results obtained in vitro validate the use of this plant in ethnopharmacology, and open opportunities for the development of new oral anticariogenic agents, originated by plants that can inhibit pathogenic biofilm that leads to the development of caries.

High Counts and Anthracene Degradation Ability of Streptococcus mutans and Veillonella parvula Isolated From the Oral Cavity of Cigarette Smokers and Non-smokers

The composition and metabolic functions of oral microbiota are affected by many factors including smoking leading to several health problems. Cigarette smoking is associated with changes in oral microbiota composition and function. However, it is not known if the depletion of certain bacterial genera and species is due to specific toxins in cigarette smoke, or indirectly due to competition for colonization with smoking-enriched bacteria. Therefore, the aim of this study was to determine the effect of cigarette smoking on the microbial prevalence and polycyclic aromatic hydrocarbons (PAHs) biodegradation of selected enriched and depleted oral bacteria from oral microbiota of smokers compared to that in non-smokers. Samples of oral rinse from smokers and non-smokers were collected (n = 23, 12 smokers and 11 non-smokers) and screened for oral bacterial strains of Streptococcus mutans, Lactobacillus spp., and Veillonella spp. Comparing counts, S. mutans, V. tobetsuensis, and V. dispar showed higher counts in smokers compared to non-smokers while the Lactobacillus spp. were higher in non-smokers. Lactobacillus fermentum was prevalent in smokers, representing 91.67% of the total Lactobacillus spp. isolates. The biodegradation potential of anthracene; a representative of PAHs of collected isolates, in single and mixed cultures, was assayed with anthracene as the sole source of carbon using 2,6-dichlorophenol indophenol (2,6-DCPIP) as indicator. S. mutans isolates recovered from smokers showed higher degradation of anthracene compared to those recovered from non-smokers. The anaerobic anthracene biodegradation activity of V. parvula isolates from non-smokers was the highest among all isolates of the three recovered genera from the same subject. The anthracene biodegradation potential of Lactobacillus spp. was variable. Combinations of isolated bacteria in co-cultures showed that Lactobacillus spp. interfered with anthracene biodegradation ability along with the viable counts of S. mutans and Veillonella spp. In conclusion, oral dysbiosis due to cigarette smoking was observed not only due to changes in oral bacterial relative abundance but also extended to bacterial functions such as anthracene biodegradation tested in this study. Microbe-microbe interactions changed the anthracene biodegradation potential and growth of the microbial mixture compared to their corresponding single isolates, and these changes differ according to the constituting bacteria.

Gardnerella vaginalis and Neisseria gonorrhoeae Are Effectively Inhibited by Lactobacilli with Probiotic Properties Isolated from Brazilian Cupuaçu (Theobroma grandiflorum) Fruit

In recent years, certain Lactobacillus sp. have emerged in health care as an alternative therapy for various diseases. Based on this, this study is aimed at evaluating in vitro the potential probiotics of five lactobacilli strains isolated from pulp of cupuaçu fruit fermentation against Gardnerella vaginalis and Neisseria gonorrhoeae. Our lactobacilli strains were classified as safe for use in humans, and they were tolerant to heat and pH. Our strains were biofilm producers, while hydrophobicity and autoaggregation varied from 13% to 86% and 13% to 25%, respectively. The coaggregation of lactobacilli used in this study with G. vaginalis and N. gonorrhoeae ranged from 15% to 36% and 32% to 52%, respectively. Antimicrobial activity was present in all tested Lactobacillus strains against both pathogens, and the growth of pathogens in coculture was reduced by the presence of our lactobacilli. Also, all tested lactobacilli reduced the pH of the culture, even in incubation with pathogens after 24 hours. The cell-free culture supernatants (CFCS) of all five lactobacilli demonstrated activity against the two pathogens with a halo presence and CFCS characterization assay together with gas chromatography revealed that lactic acid was the most abundant organic acid in the samples (50% to 62%). Our results demonstrated that the organic acid production profile is strain-specific. This study revealed that cupuaçu is a promising source of microorganisms with probiotic properties against genital pathogens. We demonstrated by in vitro tests that our Lactobacillus strains have probiotic properties. However, the absence of in vivo tests is a limitation of our work due to the need to evaluate the interaction of our lactobacilli with pathogens in the vaginal mucosa. We believe that these findings may be useful in developing a product containing our lactobacilli and their supernatants in order to support with vaginal health.