Antimicrobial and anti-biofilm activities of Lactobacillus kefiranofaciens DD2 against oral pathogens

Lacticaseibacillus rhamnosus inhibits the development of dental caries in rat caries model and in vitro

OBJECTIVES

Dental caries result from a microbial imbalance in the oral cavity. Probiotics ecologically modulate the oral microflora to prevent caries. This study evaluated the anti-cariogenic effects of two Lacticaseibacillus rhamnosus strains in vitro and in vivo to provide a more theoretical basis for its clinical applications in caries prevention.

METHODS

In the study, cariogenic biofilms were grown with L. rhamnosus (LGG) or L. rhamnosus ATCC 7469 and analyzed. Quantitative real-time PCR (qPCR), Scanning Electron Microscope (SEM), and Confocal laser scanning microscope (CLSM) were used to detect the changes in the composition and architectures; cariogenic activity was measured by the lactic acid production and Transverse Microradiography (TMR). The effects of LGG on the 12 Sprague-Dawley rat caries model were assessed using Keyes scores and micro-CT analysis. Oral microbiome changes were evaluated through 16S rRNA gene high-throughput sequencing.

RESULTS

L. rhamnosus can reduce cariogenic bacteria in biofilm by 14.7 % to 48.9 %, with LGG exhibiting more potent inhibitory effects. Both strains of L. rhamnosus can adhere to the surface of biofilms, reduce the extracellular polysaccharides (EPS) matrix, and loosen the biofilm structure. L. rhamnosus inhibited cariogenic activity by reducing the lactic acid production in biofilms. The bovine enamel blocks presented lower mineral loss values and lesion depth values in the group Core+L.rh and Core+LGG. LGG-ingested rats had significantly lower levels of moderate dentin lesions and higher mineral density than the control group. The 16 s rRNA gene sequencing revealed that LGG regulated the beta diversity of the oral microbial community in the rat dental caries model.

CONCLUSIONS

This study revealed the promising potential of L. rhamnosus, especially the LGG strain, in the ecological prevention of dental caries.

CLINICAL SIGNIFICANCE

Probiotics may provide a strategy for preventing caries by regulating the oral microecological balance. The study revealed the promising anti-caries potential of the LGG probiotic strain in vivo and in vitro. It is expected that LGG could be used as an oral probiotic for the clinical prevention and treatment of caries.

Simultaneous application of oral and intravaginal probiotics for Helicobacter pylori and its antibiotic-therapy-induced vaginal dysbacteriosis

Helicobacter pylori is a prevalent bacterial pathogen globally, implicated in various gastrointestinal disorders. Current recommended antibiotic therapies for H. pylori infection have been proven to be therapeutically insufficient, with low eradication rates and high recurrence rates. Emerging evidence suggests that antibiotic therapy for H. pylori can lead to gastrointestinal and subsequent vaginal dysbiosis, posing challenges for conventional antibiotic approaches. Thus, this article proposes a novel probiotic therapy involving simultaneous oral and intra-vaginal probiotic administration alongside antibiotics for H. pylori treatment, aiming to enhance eradication rates and mitigate dysbiosis. We begin by providing an overview of gastrointestinal and vaginal microbiota and their interconnectedness through the vagina-gut axis. We then review the efficacy of current antibiotic regimens for H. pylori and discuss how antibiotic treatment impacts the vaginal microenvironment. To explore the feasibility of this approach, we evaluate the effectiveness of oral and intra-vaginal probiotics in restoring normal microbiota in the gastrointestinal and vaginal tracts, respectively. Additionally, we analyze the direct mechanisms by which oral and intra-vaginal probiotics act on their respective tracts and discuss potential cross-tract mechanisms. Considering the potential synergistic therapeutic effects of probiotics in both the gastrointestinal and vaginal tracts, dual-channel probiotic therapy holds promise as a more effective approach for H. pylori eradication and dysbiosis mitigation, presenting a novel concept in the collaborative treatment of gastrointestinal and genital disorders.

Molecular Aspects of the Functioning of Pathogenic Bacteria Biofilm Based on Quorum Sensing (QS) Signal-Response System and Innovative Non-Antibiotic Strategies for Their Elimination

One of the key mechanisms enabling bacterial cells to create biofilms and regulate crucial life functions in a global and highly synchronized way is a bacterial communication system called quorum sensing (QS). QS is a bacterial cell-to-cell communication process that depends on the bacterial population density and is mediated by small signalling molecules called autoinducers (AIs). In bacteria, QS controls the biofilm formation through the global regulation of gene expression involved in the extracellular polymeric matrix (EPS) synthesis, virulence factor production, stress tolerance and metabolic adaptation. Forming biofilm is one of the crucial mechanisms of bacterial antimicrobial resistance (AMR). A common feature of human pathogens is the ability to form biofilm, which poses a serious medical issue due to their high susceptibility to traditional antibiotics. Because QS is associated with virulence and biofilm formation, there is a belief that inhibition of QS activity called quorum quenching (QQ) may provide alternative therapeutic methods for treating microbial infections. This review summarises recent progress in biofilm research, focusing on the mechanisms by which biofilms, especially those formed by pathogenic bacteria, become resistant to antibiotic treatment. Subsequently, a potential alternative approach to QS inhibition highlighting innovative non-antibiotic strategies to control AMR and biofilm formation of pathogenic bacteria has been discussed.

Milk and Its Derivatives as Sources of Components and Microorganisms with Health-Promoting Properties: Probiotics and Bioactive Peptides

Milk is a source of many valuable nutrients, including minerals, vitamins and proteins, with an important role in adult health. Milk and dairy products naturally containing or with added probiotics have healthy functional food properties. Indeed, probiotic microorganisms, which beneficially affect the host by improving the intestinal microbial balance, are recognized to affect the immune response and other important biological functions. In addition to macronutrients and micronutrients, biologically active peptides (BPAs) have been identified within the amino acid sequences of native milk proteins; hydrolytic reactions, such as those catalyzed by digestive enzymes, result in their release. BPAs directly influence numerous biological pathways evoking behavioral, gastrointestinal, hormonal, immunological, neurological, and nutritional responses. The addition of BPAs to food products or application in drug development could improve consumer health and provide therapeutic strategies for the treatment or prevention of diseases. Herein, we review the scientific literature on probiotics, BPAs in milk and dairy products, with special attention to milk from minor species (buffalo, sheep, camel, yak, donkey, etc.); safety assessment will be also taken into consideration. Finally, recent advances in foodomics to unveil the probiotic role in human health and discover novel active peptide sequences will also be provided.

Anti-bacterial, anti-biofilm and anti-quorum sensing activities of honey: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Man has used honey to treat diseases since ancient times, perhaps even before the history of medicine itself. Several civilizations have utilized natural honey as a functional and therapeutic food to ward off infections. Recently, researchers worldwide have been focusing on the antibacterial effects of natural honey against antibiotic-resistant bacteria.

AIM OF THE STUDY

This review aims to summarize research on the use of honey properties and constituents with their anti-bacterial, anti-biofilm, and anti-quorum sensing mechanisms of action. Further, honey's bacterial products, including probiotic organisms and antibacterial agents which are produced to curb the growth of other competitor microorganisms is addressed.

MATERIALS AND METHODS

In this review, we have provided a comprehensive overview of the antibacterial, anti-biofilm, and anti-quorum sensing activities of honey and their mechanisms of action. Furthermore, the review addressed the effects of antibacterial agents of honey from bacterial origin. Relevant information on the antibacterial activity of honey was obtained from scientific online databases such as Web of Science, Google Scholar, ScienceDirect, and PubMed.

RESULTS

Honey's antibacterial, anti-biofilm, and anti-quorum sensing activities are mostly attributed to four key components: hydrogen peroxide, methylglyoxal, bee defensin-1, and phenolic compounds. The performance of bacteria can be altered by honey components, which impact their cell cycle and cell morphology. To the best of our knowledge, this is the first review that specifically summarizes every phenolic compound identified in honey along with their potential antibacterial mechanisms of action. Furthermore, certain strains of beneficial lactic acid bacteria such as Bifidobacterium, Fructobacillus, and Lactobacillaceae, as well as Bacillus species can survive and even grow in honey, making it a potential delivery system for these agents.

CONCLUSION

Honey could be regarded as one of the best complementary and alternative medicines. The data presented in this review will enhance our knowledge of some of honey's therapeutic properties as well as its antibacterial activities.

Evaluation of the Cariogenic and Anti-Cariogenic Potential of Human Colostrum and Colostrum-Derived Probiotics: Impact on S. mutans Growth, Biofilm Formation, and L. rhamnosus Growth

Human colostrum (HC) is essential for oral health as it is rich in probiotics that could affect the growth of the cariogenic S. mutans and its biofilm formation; hindering dental caries in advance. In this study, HC was collected from 36 healthy mothers 1-3 days postpartum. The effect of HC on oral health was carried out by assessing the impact of HC and its derived probiotics' cell-free supernatants (CFS) on the growth of S. mutans (using modified well diffusion) and its biofilm formation (using microtiter plate assay). Moreover, the effect of whole HC on L. rhamnosus, a probiotic oral bacterium, was examined. Probiotics were isolated and identified phenotypically by API 50 CH carbohydrate fermentation and genotypically by 16S rRNA amplification. The in vitro study revealed that HC has cariogenic activity and is associated with biofilm formation. Biofilm strength was inversely proportional to HC dilution (p-value < 0.0001). Nevertheless, HC and colostrum-derived probiotics improve oral health by inhibiting the growth of caries-inducing S. mutans with lower inhibition to L. rhamnosus probiotics. The CFS of isolated probiotics reduced the biofilm formation via the cariogenic S. mutans. These results are not only promising for caries eradication, but they also highlight the importance of breastfeeding infants from their first hours to shape healthy oral microbiota, protecting them from various diseases including dental caries.

Effects of probiotic administration on overweight or obese children: a meta-analysis and systematic review

BACKGROUND

This paper aimed to examine the effects of probiotics on eight factors in overweight or obese children by meta-analysis, namely, body mass index (BMI), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), adiponectin, leptin and tumor necrosis factor-α (TNF-α) and summarize the mechanisms of action of probiotics based on the existing researches.

METHODS

Six databases (PubMed, Web of Science, Embase, Cochrane Library, SinoMed and CNKI) were searched until March 2023. Review Manager 5.4 was used for meta-analysis. The data were analysed using weighted mean differences (WMDs) or standardized mean differences (SMDs) under a fixed effect model or random effect model to observe the effects of probiotic administration on the included indicators.

RESULTS

Four publications with a total of 206 overweight or obesity children were included. According to the meta-analysis, probiotics were able to significantly decrease the levels of HDL-C (MD, 0.06; 95% CI 0.03, 0.09; P = 0.0001), LDL-C (MD, - 0.06; 95% CI - 0.12, - 0.00; P = 0.04), adiponectin (MD, 1.39; 95% CI 1.19, 1.59; P < 0.00001), leptin (MD, - 2.72; 95% CI - 2.9, - 2.54; P < 0.00001) and TNF-α (MD, - 4.91; 95% CI - 7.15, - 2.67; P < 0.0001) compared to those in the placebo group. Still, for BMI, the palcebo group seemed to be better than the probiotic group (MD, 0.85; 95% CI 0.04, 1.66; P = 0.04). TC (MD, - 0.05; 95% CI - 0.12, 0.02; P = 0.14) and TG (MD, - 0.16; 95% CI - 0.36, 0.05; P = 0.14) were not different between two groups.

CONCLUSIONS

This review drew that probiotics might act as a role in regulating HDL-C, LDL-C, adiponectin, leptin and TNF-α in overweight or obesity children. Additionally, our systematic review yielded that probiotics might regulate lipid metabolism and improve obese associated symptoms by some paths. This meta-analysis has been registered at PROSPERO with ID: CRD42023408359.

Impact of cell-free supernatant of lactic acid bacteria on Staphylococcus aureus biofilm and its metabolites

Introduction

A safe bio-preservative agent, lactic acid bacteria (LAB) can inhibit the growth of pathogenic bacteria and spoilage organisms. Its cell-free supernatant (LAB-CFS), which is rich in bioactive compounds, is what makes LAB antibacterial work.

Methods

This study focused on the changes in biofilm activity and related metabolic pathways of S. aureus treated with lactic acid bacteria planktonic CFS (LAB-pk-CFS) and biofilm state (LAB-bf-CFS).

Results

The findings demonstrated that the LAB-CFS treatment considerably slowed Staphylococcus aureus (S. aureus) growth and prevented it from forming biofilms. Additionally, it inhibits the physiological traits of the S. aureus biofilm, including hydrophobicity, motility, eDNA, and PIA associated to the biofilm. The metabolites of S. aureus biofilm treated with LAB-CFS were greater in the LAB-bf-CFS than they were in the LAB-pk-CFS, according to metabolomics studies. Important metabolic pathways such amino acids and carbohydrates metabolism were among the most noticeably altered metabolic pathways.

Discussion

These findings show that LAB-CFS has a strong potential to combat S. aureus infections.

Postbiotic Metabolite of Lactiplantibacillus plantarum PD18 against Periodontal Pathogens and Their Virulence Markers in Biofilm Formation

Alternative methods to reduce infectious diseases caused by bacterial pathogens and their virulence factors, biofilm formations, have arisen to reduce the pressure on existing or currently developed disinfectants and antimicrobial agents. The current strategies for reducing the severity of periodontal pathogen-caused disease by using beneficial bacteria and their metabolites are highly desirable. Probiotic strains of lactobacilli related to foods from Thai-fermented foods were selected and their postbiotic metabolites (PM) were isolated with inhibitory activity on periodontal pathogens and their biofilm formation. The PM from Lactiplantibacillus plantarum PD18 (PD18 PM) with the highest antagonistic effect against Streptococcus mutans, Porphyromonas gingivalis, Tannerella forsythia and Prevotella loescheii was selected from 139 Lactobacillus isolates. The minimal inhibitory concentration (MIC) and minimum biofilm inhibitory concentration (MBIC) values of PD18 PM against the pathogens ranged from 1:2 to 1:4. The PD18 PM demonstrated the ability to prevent the biofilm formation of S. mutans and P. gingivalis by showing a significant reduction in viable cells, high percentages of biofilm inhibition at 92.95 and 89.68%, and the highest effective contact times at 5 and 0.5 min, respectively. L. plantarum PD18 PM showed potential as a promising natural adjunctive agent to inhibit periodontal pathogens and their biofilms.

Anti-Bacterial and Anti-Biofilm Activities of Anandamide against the Cariogenic Streptococcus mutans

Streptococcus mutans is a cariogenic bacterium in the oral cavity involved in plaque formation and dental caries. The endocannabinoid anandamide (AEA), a naturally occurring bioactive lipid, has been shown to have anti-bacterial and anti-biofilm activities against Staphylococcus aureus. We aimed here to study its effects on S. mutans viability, biofilm formation and extracellular polysaccharide substance (EPS) production. S. mutans were cultivated in the absence or presence of various concentrations of AEA, and the planktonic growth was followed by changes in optical density (OD) and colony-forming units (CFU). The resulting biofilms were examined by MTT metabolic assay, Crystal Violet (CV) staining, spinning disk confocal microscopy (SDCM) and high-resolution scanning electron microscopy (HR-SEM). The EPS production was determined by Congo Red and fluorescent dextran staining. Membrane potential and membrane permeability were determined by diethyloxacarbocyanine iodide (DiOC2(3)) and SYTO 9/propidium iodide (PI) staining, respectively, using flow cytometry. We observed that AEA was bactericidal to S. mutans at 12.5 µg/mL and prevented biofilm formation at the same concentration. AEA reduced the biofilm thickness and biomass with concomitant reduction in total EPS production, although there was a net increase in EPS per bacterium. Preformed biofilms were significantly affected at 50 µg/mL AEA. We further show that AEA increased the membrane permeability and induced membrane hyperpolarization of these bacteria. AEA caused S. mutans to become elongated at the minimum inhibitory concentration (MIC). Gene expression studies showed a significant increase in the cell division gene ftsZ. The concentrations of AEA needed for the anti-bacterial effects were below the cytotoxic concentration for normal Vero epithelial cells. Altogether, our data show that AEA has anti-bacterial and anti-biofilm activities against S. mutans and may have a potential role in preventing biofilms as a therapeutic measure.

Anti-Quorum Sensing Activity of Probiotics: The Mechanism and Role in Food and Gut Health

Background: Quorum sensing (QS) is a cell-to-cell communication mechanism that occurs between inter- and intra-bacterial species and is regulated by signaling molecules called autoinducers (AIs). It has been suggested that probiotics can exert a QS inhibitory effect through their metabolites. Purpose: To provide an overview of (1) the anti-QS activity of probiotics and its mechanism against foodborne pathogenic and spoilage bacteria; (2) the potential role of the QS of probiotics in gut health; and (3) the impact of microencapsulation on QS. Results: Lactobacillus species have been extensively studied for their anti-QS activity and have been found to effectively disrupt QS in vitro. However, their effectiveness in a food matrix is yet to be determined as they interfere with the AI receptor or its synthesis. QS plays an important role in both the biofilm formation of probiotics and pathogenic bacteria. Moreover, in vitro and animal studies have shown that QS molecules can modulate cytokine responses and gut dysbiosis and maintain intestinal barrier function. In this scenario, microencapsulation was found to enhance AI activity. However, its impact on the anti-QS activity of probiotics and its underlying mechanism remains unclear. Conclusions: Probiotics are potential candidates to block QS activity in foodborne pathogenic and food spoilage bacteria. Microencapsulation increases QS efficacy. However, more research is still needed for the identification of the QS inhibitory metabolites from probiotics and for the elucidation of the anti-QS mechanism of probiotics (microcapsules and free cells) in food and the human gut.

Identification of a Novel Strain Lactobacillus Reuteri and Anti-Obesity Effect through Metabolite Indole-3-Carboxaldehyde in Diet-Induced Obese Mice

The potentially beneficial effects of probiotics in the treatment of obesity have been generally demonstrated. In the present study, a new strain of Lactobacillus reuteri SY523 (L. reuteri SY523) with an anti-obesity effect was isolated from the fecal microbiota of diet-induced obese mice. Untargeted metabolomics analysis of mice serum showed that the significantly differential metabolite indole-3-carboxaldehyde (3-IAId) was markedly elevated in the L. reuteri SY523-treated group, and interestingly, the abundance of 3-IAId was significantly negatively associated with obesity-related indicators. As expected, in the HepG2 cell induced by free fatty acids, the potential activity of 3-IAId in restraining lipid deposition was verified. Further, we found that 3-IAId was involved in the anti-obesity effect of L. reuteri SY523 mainly via regulating the cGMP/cAMP signaling pathway. The highlight of this study lies in clarifying the pivotal role of metabolite 3-IAId in the anti-obesity effect induced by L. reuteri SY523, which is conducive to the development of probiotics for anti-obesity agents.

Genetic and phenotypic assessment of the antimicrobial activity of three potential probiotic lactobacilli against human enteropathogenic bacteria

Introduction

Lactobacilli are avid producers of antimicrobial compounds responsible for their adaptation and survival in microbe-rich matrices. The bactericidal or bacteriostatic ability of lactic acid bacteria (LAB) can be exploited for the identification of novel antimicrobial compounds to be incorporated in functional foodstuffs or pharmaceutical supplements. In this study, the antimicrobial and antibiofilm properties of Lactiplantibacillus pentosus L33, Lactiplantibacillus plantarum L125 and Lacticaseibacillus paracasei SP5, previously isolated form fermented products, were examined, against clinical isolates of Staphylococcus aureus, Salmonella enterica subsp. enterica serovar Enteritidis and Escherichia coli.

Methods

The ability of viable cells to inhibit pathogen colonization on HT-29 cell monolayers, as well as their co-aggregation capacity, were examined utilizing the competitive exclusion assay. The antimicrobial activity of cell-free culture supernatants (CFCS) was determined against planktonic cells and biofilms, using microbiological assays, confocal microscopy, and gene expression analysis of biofilm formation-related genes. Furthermore, in vitro analysis was supplemented with in silico prediction of bacteriocin clusters and of other loci involved in antimicrobial activity.

Results

The three lactobacilli were able to limit the viability of planktonic cells of S. aureus and E. coli in suspension. Greater inhibition of biofilm formation was recorded after co-incubation of S. enterica with the CFCS of Lc. paracasei SP5. Predictions based on sequence revealed the ability of strains to produce single or two-peptide Class II bacteriocins, presenting sequence and structural conservation with functional bacteriocins.

Discussion

The efficiency of the potentially probiotic bacteria to elicit antimicrobial effects presented a strain- and pathogen-specific pattern. Future studies, utilizing multi-omic approaches, will focus on the structural and functional characterization of molecules involved in the recorded phenotypes.

Exploration of the Main Antibiofilm Substance of Lactobacillus plantarum ATCC 14917 and Its Effect against Streptococcus mutans

Dental plaque, a complex biofilm system established by cariogenic bacteria such as Streptococcus mutans (S. mutans), is the initiator of dental caries. Studies have found that the cell-free supernatant (CFS) of Lactobacilli could inhibit S. mutans biofilm formation. However, the main antibiofilm substance of the Lactobacilli CFS that acts against S. mutans is unclear. The present study found that the CFS of Lactobacillus plantarum (L. plantarum) ATCC 14917 had the strongest antibiofilm effect among the five tested oral Lactobacilli. Further bioassay-guided isolation was performed to identify the main antibiofilm substance. The antibiofilm effect of the end product, named 1-1-4-3, was observed and the structure of it was elucidated by using Q-TOF MS, 2D NMR and HPLC. The results showed that several components in the CFS had an antibiofilm effect; however, the effect of 1-1-4-3 was the strongest, as it could reduce the generation of exopolysaccharides and make the biofilm looser and thinner. After structure elucidation and validation, 1-1-4-3 was identified as a mixture of lactic acid (LA) and valine. Additionally, LA was shown to be the main antibiofilm substance in 1-1-4-3. In summary, this study found that the antibiofilm effect of the L. plantarum CFS against S. mutans was attributable to the comprehensive effect of multiple components, among which LA played a dominant role.

Potential oral probiotic Lactobacillus pentosus MJM60383 inhibits Streptococcus mutans biofilm formation by inhibiting sucrose decomposition

Streptococcus mutans is known as a contributor to dental caries. In this work, Lactobacillus pentosus MJM60383 was selected for its strong antagonistic activity against S. mutans and was characterized by good oral probiotic properties including lysozyme tolerance, adhesive ability to oral cells, good aggregation (auto-aggregation, co-aggregation) ability, hydrogen peroxide production and inhibition of biofilm formation of S. mutans. L. pentosus MJM60383 also exhibited safety as a probiotic characterized by no hemolytic activity, no D-lactate production, no biogenic amine production, and susceptibility to antibiotics. Furthermore, the biofilm formation of S. mutans was also significantly inhibited by the supernatant of L. pentosus MJM60383. An anti-biofilm mechanism study revealed that sucrose decomposition and the production of water-insoluble exopolysaccharides by S. mutans were inhibited by the treatment with L. pentosus MJM60383 supernatant. Real-time PCR analysis indicated that the supernatant of L. pentosus MJM60383 significantly inhibited the mRNA expression of S. mutans glycosyltransferases, which synthesize glucan to construct biofilm architecture and mediate bacterial adherence. Our study demonstrated L. pentosus MJM60383 as a potential oral probiotic and revealed its anti-biofilm mechanism.

BIOFILM: FORMATION AND NATURAL PRODUCTS' APPROACH TO CONTROL - A REVIEW

Biofilm formation, especially on indwelling medical devices such as catheters, can result in infections and substantially affect patients' quality of life. Biofilm-associated infections have led to increased morbidity and mortality, increased cost of treatment, and length of hospital stay. However, all of the identified consequences of the biofilm-associated infections had been attributed to the reduced susceptibility of biofilm to conventional antimicrobial agents which has necessitated the development of a new strategy for biofilm infections control, thereby making a search for more effective antimicrobial agents from plant source inevitable. So far, some antimicrobial agents (crude or isolated compounds) from plant sources affect a specific stage of biofilm development while a few of them have been developed into a suitable dosage form for biofilm control. In this review, an attempt is made to look into some definitions of biofilm by "biofilmologists", stages in biofilm formation, mechanisms of resistance in biofilm, biofilm control strategies, the use of some natural products in biofilm control and concepts of probiotics as agents of biofilm control.

Characterization and potential oral probiotic properties of Lactobacillus plantarum FT 12 and Lactobacillus brevis FT 6 isolated from Malaysian fermented food

OBJECTIVE

This study aims to characterise the lactic acid bacteria (LAB) isolated from local Malaysian fermented foods with oral probiotics properties.

DESIGN

The LAB strains isolated from Malaysian fermented foods, Lactobacillus brevis FT 6 and Lactobacillus plantarum FT 12, were assessed for their antimicrobial properties against Porphyromonas gingivalis ATCC 33277 via disc diffusion assay. Anti-biofilm properties were determined by treating the overnight P. gingivalis ATCC 33277 biofilm with different concentrations of LAB cell-free supernatant (LAB CFS). Quantification of biofilm was carried out by measuring the optical density of stained biofilm. The ability of L. brevis FT 6 and L. plantarum FT 12 to tolerate salivary amylase was also investigated. Acid production with different sugars was carried out by pH measurement and screening for potential antimicrobial organic acid by disc diffusion assay of neutralised probiotics CFS samples. In this study, L. rhamnosus ATCC 7469, a commercial strain was used to compare the efficacy of the isolated strain with the commercial strain.

RESULTS

Lactobacillus brevis FT 6 and L. plantarum FT 12 possess antimicrobial activity against P. gingivalis with inhibition diameters of more than 10 mm, and the results were comparable with L. rhamnosus ATCC 7469. The MIC and MBC assay results for all tested strains were recorded to be 25 µl/µl concentration. All LAB CFS reduced biofilm formation proportionally to the CFS concentration and tolerated salivary amylase with more than 50% viability. Overnight cultures of all lactic acid bacteria strains showed a pH reduction and neutralised CFS of all lactic acid bacteria strains did not show any inhibition towards P. gingivalis.

CONCLUSIONS

These results indicate that the isolated probiotics have the potential as probiotics to be used as a supportive oral health treatment, especially against a periodontal pathogen, P. gingivalis.

Survivability of Kluyveromyces marxianus Isolated From Korean Kefir in a Simulated Gastrointestinal Environment

Kluyveromyces marxianus accounts for > 90% of the yeast population of kefir, and recently, its probiotic potential has been actively explored with a focus on its health benefits and safety. Herein, the survivability of five kefir-isolated K. marxianus strains (Km A1–A5) in a simulated gastrointestinal (GI) environment was evaluated and compared with those of commercial probiotic yeast, Saccharomyces boulardii MYA-796. To further explore the potential to survive in the host GI tract, biochemical activities, hydrophobicity assay, biofilm formation, auto-aggregation analysis, and phenol tolerance of the strains were assessed. K. marxianus A4 exhibited the best survivability among all tested strains, including the clinically proven probiotic yeast strain S. boulardii MYA-796 (p = 0.014) in the artificial GI tract ranging from pH 2.0 to 7.5. In addition, the five K. marxianus strains and S. boulardii MYA-796 displayed different assimilation of lactose, xylitol, D-sorbitol, and DL-lactate, indicating that K. marxianus metabolized a wide range of substances and, thus, might be more feasible to nourish themselves in the host GI tract for survival. K. marxianus strains showed a greater hydrophobicity of cell surface, abilities to biofilm formation and auto-aggregation, and phenol tolerance than S. boulardii MYA-796, suggesting greater potential for survival in the host GI tract.

Lactobacilli as Anti-biofilm Strategy in Oral Infectious Diseases: A Mini-Review

The spread of biofilm-related diseases in developed countries has led to increased mortality rates and high health care costs. A biofilm is a community of microorganisms that is irreversibly attached to a surface, behaving very differently from planktonic cells and providing resistance to antimicrobials and immune response. Oral diseases are an excellent example of infection associated with the formation of highly pathogenic biofilms. It is generally accepted that, when the oral homeostasis is broken, the overgrowth of pathogens is facilitated. Among them, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans are the main etiological agents of periodontitis, while Streptococcus mutans is strongly associated with the onset of dental caries. Other microorganisms, such as the fungus Candida albicans, may also be present and contribute to the severity of infections. Since the common antibiotic therapies usually fail to completely eradicate biofilm-related oral diseases, alternative approaches are highly required. In this regard, the topical administration of probiotics has recently gained interest in treating oral diseases. Thus, the present mini-review focuses on the possibility of using Lactobacillus spp. as probiotics to counteract biofilm-mediated oral infections. Many evidence highlight that Lactobacillus living cells can impede the biofilm formation and eradicate mature biofilms of different oral pathogens, by acting through different mechanisms. Even more interestingly, lactobacilli derivatives, namely postbiotics (soluble secreted products) and paraprobiotics (cell structural components) are able to trigger anti-biofilm effects too, suggesting that they can represent a novel and safer alternative to the use of viable cells in the management of biofilm-related oral diseases.

Isolation and characterization of halophilic Kocuria salsicia strains from cheese brine

Kocuria salsicia can survive in extreme environments and cause infections, including catheter-related bacteremia, in humans. Here, we investigated and evaluated the characteristics of nine K. salsicia strains (KS1–KS9) isolated from cheese brine from a farmstead cheese-manufacturing plant in Korea from June to December, 2020. Staphylococcus aureus American Type Culture Collection (ATCC) 29213 was used as a positive control in the growth curve analysis and biofilm-formation assays. All K. salsicia isolates showed growth at 15% salt concentration and temperatures of 15°C, 25°C, 30°C, 37°C, and 42°C. KS6 and KS8 showed growth at 5°C, suggesting that they are potential psychrotrophs. In the biofilm-formation analysis via crystal violet staining, KS6 exhibited the highest biofilm-forming ability at various temperatures and media [phosphate buffered saline, nutrient broth (NB), and NB containing 15% sodium chloride]. At 25°C and 30°C, KS3, KS6, and KS8 showed higher biofilm-forming ability than S. aureus ATCC 29213. The antimicrobial resistance of the isolates was evaluated using the VITEK^® 2 system; most isolates were resistant to marbofloxacin and nitrofurantoin (both 9/9, 100%), followed by enrofloxacin (7/9, 77.8%). Five of the nine isolates (5/9, 55.6%) showed multidrug resistance. Our study reports the abilities of K. salsicia to grow in the presence of high salt concentrations and at relatively low temperatures, along with its multidrug resistance and tendency to form biofilms.

Cannabinoid control of gingival immune activation in chronically SIV-infected rhesus macaques involves modulation of the indoleamine-2,3-dioxygenase-1 pathway and salivary microbiome

BACKGROUND

HIV/SIV-associated periodontal disease (gingivitis/periodontitis) (PD) represents a major comorbidity affecting people living with HIV (PLWH) on combination anti-retroviral therapy (cART). PD is characterized by chronic inflammation and dysbiosis. Nevertheless, the molecular mechanisms and use of feasible therapeutic strategies to reduce/reverse inflammation and dysbiosis remain understudied and unaddressed.

METHODS

Employing a systems biology approach, we report molecular, metabolome and microbiome changes underlying PD and its modulation by phytocannabinoids [delta-9-tetrahydrocannabinol (Δ9-THC)] in uninfected and SIV-infected rhesus macaques (RMs) untreated (VEH-untreated/SIV) or treated with vehicle (VEH/SIV) or Δ9-THC (THC/SIV).

FINDINGS

VEH- untreated/SIV but not THC/SIV RMs showed significant enrichment of genes linked to anti-viral defense, interferon-β, NFκB, RIG-1, and JAK-STAT signaling. We focused on the anti-microbial DUOX1 and immune activation marker IDO1 that were reciprocally regulated in the gingiva of VEH-untreated/SIV RMs. Both proteins localized to the gingival epithelium and CD163+ macrophages, and showed differential expression in the gingiva of THC/SIV and VEH/SIV RMs. Additionally, inflammation-associated miR-21, miR-142-3p, miR-223, and miR-125a-5p showed significantly higher expression in the gingiva of VEH/SIV RMs. In human primary gingival epithelial cells, miR-125a-5p post-transcriptionally downregulated DUOX1 and THC inhibited IDO1 protein expression through a cannabinoid receptor-2 mediated mechanism. Interestingly, THC/SIV RMs showed relatively reduced plasma levels of kynurenine, kynurenate, and the neurotoxic quinolinate compared to VEH/SIV RMs at 5 months post SIV infection (MPI). Most importantly, THC blocked HIV/SIV-induced depletion of Firmicutes and Bacteroidetes, and reduced Gammaproteobacteria abundance in saliva. Reduced IDO1 protein expression was associated with significantly (p<0.05) higher abundance of Prevotella, Lactobacillus (L. salivarius, L. buchneri, L. fermentum, L. paracasei, L. rhamnosus, L. johnsonii) and Bifidobacteria and reduced abundance of the pathogenic Porphyromonas cangingivalis and Porphyromonas macacae at 5MPI.

INTERPRETATION

The data provides deeper insights into the molecular mechanisms underlying HIV/SIV-induced PD and more importantly, the anti-inflammatory and anti-dysbiotic properties of THC in the oral cavity. Overall, these translational findings suggest that phytocannabinoids may help reduce gingival/systemic inflammation, salivary dysbiosis and potentially metabolic disease/syndrome in PLWH on cART and those with no access to cART or do not suppress the virus under cART.

FUNDING

Research reported in this publication was supported by the National Institutes of Health Award Numbers R01DA052845 (MM and SNB), R01DA050169 (MM and CO), R01DA042524 and R56DE026930 (MM), and P51OD011104 and P51OD011133. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

Using Lactobacilli to Fight Escherichia coli and Staphylococcus aureus Biofilms on Urinary Tract Devices

The low efficacy of conventional treatments and the interest in finding natural-based approaches to counteract biofilm development on urinary tract devices have promoted the research on probiotics. This work evaluated the ability of two probiotic strains, Lactobacillus plantarum and Lactobacillus rhamnosus, in displacing pre-formed biofilms of Escherichia coli and Staphylococcus aureus from medical-grade silicone. Single-species biofilms of 24 h were placed in contact with each probiotic suspension for 6 h and 24 h, and the reductions in biofilm cell culturability and total biomass were monitored by counting colony-forming units and crystal violet assay, respectively. Both probiotics significantly reduced the culturability of E. coli and S. aureus biofilms, mainly after 24 h of exposure, with reduction percentages of 70% and 77% for L. plantarum and 76% and 63% for L. rhamnosus, respectively. Additionally, the amount of E. coli biofilm determined by CV staining was maintained approximately constant after 6 h of probiotic contact and significantly reduced up to 67% after 24 h. For S. aureus, only L. rhamnosus caused a significant effect on biofilm amount after 6 h of treatment. Hence, this study demonstrated the potential of lactobacilli to control the development of pre-established uropathogenic biofilms.

Lactobacillus plantarum Lipoteichoic Acids Possess Strain-Specific Regulatory Effects on the Biofilm Formation of Dental Pathogenic Bacteria

Bacterial biofilm residing in the oral cavity is closely related to the initiation and persistence of various dental diseases. Previously, we reported the anti-biofilm activity of Lactobacillus plantarum lipoteichoic acid (Lp.LTA) on a representative dental cariogenic pathogen, Streptococcus mutans. Since LTA structure varies in a bacterial strain-specific manner, LTAs from various L. plantarum strains may have differential anti-biofilm activity due to their distinct molecular structures. In the present study, we isolated Lp.LTAs from four different strains of L. plantarum (LRCC 5193, 5194, 5195, and 5310) and compared their anti-biofilm effects on the dental pathogens, including S. mutans, Enterococcus faecalis, and Streptococcus gordonii. All Lp.LTAs similarly inhibited E. faecalis biofilm formation in a dose-dependent manner. However, their effects on S. gordonii and S. mutans biofilm formation were different: LRCC 5310 Lp.LTA most effectively suppressed the biofilm formation of all strains of dental pathogens, while Lp.LTAs from LRCC 5193 and 5194 hardly inhibited or even enhanced the biofilm formation. Furthermore, LRCC 5310 Lp.LTA dramatically reduced the biofilm formation of the dental pathogens on the human dentin slice infection model. Collectively, these results suggest that Lp.LTAs have strain-specific regulatory effects on biofilm formation of dental pathogens and LRCC 5310 Lp.LTA can be used as an effective anti-biofilm agent for the prevention of dental infectious diseases.

Probiotics as Therapeutic Tools against Pathogenic Biofilms: Have We Found the Perfect Weapon?

Bacterial populations inhabiting a variety of natural and human-associated niches have the ability to grow in the form of biofilms. A large part of pathological chronic conditions, and essentially all the bacterial infections associated with implanted medical devices or prosthetics, are caused by microorganisms embedded in a matrix made of polysaccharides, proteins, and nucleic acids. Biofilm infections are generally characterized by a slow onset, mild symptoms, tendency to chronicity, and refractory response to antibiotic therapy. Even though the molecular mechanisms responsible for resistance to antimicrobial agents and host defenses have been deeply clarified, effective means to fight biofilms are still required. Lactic acid bacteria (LAB), used as probiotics, are emerging as powerful weapons to prevent adhesion, biofilm formation, and control overgrowth of pathogens. Hence, using probiotics or their metabolites to quench and interrupt bacterial communication and aggregation, and to interfere with biofilm formation and stability, might represent a new frontier in clinical microbiology and a valid alternative to antibiotic therapies. This review summarizes the current knowledge on the experimental and therapeutic applications of LAB to interfere with biofilm formation or disrupt the stability of pathogenic biofilms.

Biofilm formation and antagonistic activity of Lacticaseibacillus rhamnosus (PTCC1712) and Lactiplantibacillus plantarum (PTCC1745)

Currently, the health benefits of probiotic bacteria are well known, and this has taken up a great deal of space in food science and health, both research and operational. On the other hand, anti-biofilm properties on food pathogens in the food and pharmaceutical industries have created an attractive challenge. This study aimed to describe the inhibitory activity of cell-free supernatants (CFS), planktonic cells, and biofilm form of lactobacilus strains (L. rhamnosus and L. plantarum) against food pathogens such as Pseudomonas aeruginosa and Listeria monocytogenes. Anti-bacterial activities of the CFS of lactobacillus strains were assessed by the microplate method and via violet staining. Evaluation of the antagonistic activity of planktonic cells and biofilm of LAB were performed by the spread plate method. The results showed the incubation time of 48 h was the best time to produce biofilm. Although the planktonic states reduce the pathogens bacterial about 1 –1.5 log, but in biofilm forms, decreased L. monocytogenes about 4.5 log compared to the control, and in the case of P. aeruginosa, a growth reduction of about 2.13 log was observed. Furthermore, biofilm formation of L. monocytogenes in the presence of L. rhamnosus cell-free supernatant was more weakly than L. plantarum CFS, but their CFS effect on reducing the bacterial population of P. aeruginosa was the same. According to the study, biofilm produced by probiotic strains can be considered a new approach for biological control. Also, cell-free supernatant can be used as postbiotic in the food and pharmaceutical industries.

Lactobacillus kefiranofaciens: From Isolation and Taxonomy to Probiotic Properties and Applications

One of the main lactic acid bacterial species found in the kefir grain ecosystem worldwide is Lactobacillus kefiranofaciens, exhibiting strong auto-aggregation capacity and, therefore, being involved in the mechanism of grain formation. Its occurrence and dominance in kefir grains of various types of milk and geographical origins have been verified by culture-dependent and independent approaches using multiple growth media and regions of the 16S rRNA gene, respectively, highlighting the importance of their combination for its taxonomic identification. L. kefiranofaciens comprises two subspecies, namely kefiranofaciens and kefirgranum, but only the first one is responsible for the production of kefiran, the water-soluble polysaccharide, which is a basic component of the kefir grain and famous for its technological as well as health-promoting properties. L. kefiranofaciens, although very demanding concerning its growth conditions, can be involved in mechanisms affecting intestinal health, immunomodulation, control of blood lipid levels, hypertension, antimicrobial action, and protection against diabetes and tumors. These valuable bio-functional properties place it among the most exquisite candidates for probiotic use as a starter culture in the production of health-beneficial dairy foods, such as the kefir beverage.

Co-Culture Strategy of Lactobacillus kefiranofaciens HL1 for Developing Functional Fermented Milk

Our previous studies indicated that Lactobacillus kefiranofaciens HL1, isolated from kefir grain, has strong antioxidant activities and anti-aging effects. However, this strain is difficult to use in isolation when manufacturing fermented products due to poor viability in milk. Thus, the purpose of this study was to apply a co-culture strategy to develop a novel probiotic fermented milk rich in L. kefiranofaciens HL1. Each of four selected starter cultures was co-cultured with kefir strain HL1 in different media to evaluate their effects on microbial activity and availability of milk fermentation. The results of a colony size test on de Man, Rogosa and Sharpe (MRS) agar agar, microbial viability, and acidification performance in MRS broth and skimmed milk suggested that Lactococcus lactis subsp. cremoris APL15 is a suitable candidate for co-culturing with HL1. We then co-cultured HL1 and APL15 in skimmed milk and report remarkable improvement in fermentation ability and no negative impact on the viability of strain HL1 or textural and rheological properties of the milk. Through a co-culture strategy, we have improved the viability of kefir strain HL1 in fermented skimmed milk products and successfully developed a novel milk product with a unique flavor and sufficient probiotics.

Strategies for Interfering With Bacterial Early Stage Biofilms

Biofilm-related bacteria show high resistance to antimicrobial treatments, posing a remarkable challenge to human health. Given bacterial dormancy and high expression of efflux pumps, persistent infections caused by mature biofilms are not easy to treat, thereby driving researchers toward the discovery of many anti-biofilm molecules that can intervene in early stage biofilms formation to inhibit further development and maturity. Compared with mature biofilms, early stage biofilms have fragile structures, vigorous metabolisms, and early attached bacteria are higher susceptibility to antimicrobials. Thus, removing biofilms at the early stage has evident advantages. Many reviews on anti-biofilm compounds that prevent biofilms formation have already been done, but most of them are based on compound classifications to introduce anti-biofilm effects. This review discusses the inhibitory effects of anti-biofilm compounds on early stage biofilms formation from the perspective of the mechanisms of action, including hindering reversible adhesion, reducing extracellular polymeric substances production, interfering in the quorum sensing, and modifying cyclic di-GMP. This information can be exploited further to help researchers in designing new molecules with anti-biofilm activity.

Protective and ameliorating effects of probiotics against diet-induced obesity: A review

Diet-induced obesity is one of the major public health concerns all over the world, and obesity also contributes to the development of other chronic diseases such as non-alcoholic fatty acid liver disease, type 2 diabetes mellitus and cardiovascular diseases. Evidence shows that the pathogenesis of obesity and obesity-associated chronic diseases are closely related to dysregulation of lipid metabolism, glucose metabolism and cholesterol metabolism, and oxidative stress, endoplasmic reticulum stress, abnormal gut microbiome and chronic low-grade inflammation. Recently, in view of potential effects on lipid metabolism, glucose metabolism, cholesterol metabolism and intestinal microbiome, as well as anti-oxidative and anti-inflammatory activities, natural probiotics, including live and dead probiotics, and probiotic components and metabolites, have attracted increasing attention and are considered as novel strategies for preventing and ameliorating obesity and obesity-related chronic diseases. Specifically, this review is presented on the anti-obesity effects of probiotics and underlying molecular mechanisms, which will provide a theoretical basis of anti-obesity probiotics for the development of functional foods.

Probiotic Lactobacillus sp. Strains Inhibit Growth, Adhesion, Biofilm Formation, and Gene Expression of Bacterial Vaginosis-Inducing Gardnerella vaginalis

Gardnerella vaginalis contributes significantly to bacterial vaginosis, which causes an ecological imbalance in vaginal microbiota and presents with the depletion of Lactobacillus sp. Lactobacillus supplementation was reported to be an approach to treat bacterial vaginosis. We investigated the applicability of three Lactobacillus sp. strains (Lactobacillus delbrueckii DM8909, Lactiplantibacillus plantarum ATCC14917, and Lactiplantibacillus plantarum ZX27) based on their probiotic abilities in vitro. The three candidate Lactobacillus sp. strains for bacterial vaginosis therapy showed distinct properties in auto-aggregation ability, hydrophobicity, adhesion to cervical epithelial cells, and survivability in 0.01% hydrogen peroxide. Lpb. plantarum ZX27 showed a higher yield in producing short-chain fatty acids and lactic acid among the three candidate strains, and all three Lactobacillus sp. strains inhibited the growth and adhesion of G. vaginalis. Furthermore, we discovered that the culture supernatant of Lactobacillus sp. exhibited anti-biofilm activity against G. vaginalis. In particular, the Lpb. plantarum ZX27 supernatant treatment decreased the expression of genes related to virulence factors, adhesion, biofilm formation, metabolism, and antimicrobial resistance in biofilm-forming cells and suspended cells. Moreover, Lactobacillus sp. decreased the upregulated expression of interleukin-8 in HeLa cells induced by G. vaginalis or hydrogen peroxide. These results demonstrate the efficacy of Lactobacillus sp. application for treating bacterial vaginosis by limiting the growth, adhesion, biofilm formation, and virulence properties of G. vaginalis.

Antibacterial and antibiofilm activities of cinnamon essential oil nanoemulsion against multi-species oral biofilms

Cinnamon essential oil (CEO) has antibacterial properties, but its ability to suppress the formation of multi-species oral biofilms has not been fully elucidated. This study evaluated the antibacterial and antibiofilm activities of cinnamon essential oil nanoemulsion (CEON) against oral biofilms formed using a microcosm biofilm model. The biofilms were formed on bovine enamel specimens over a 7-day period, during which all specimens were treated with one of three solutions: 5% CEON (n = 35), 0.5% cocamidopropyl betaine (n = 35), or 0.12% chlorhexidine gluconate (CHX; n = 35). Antibacterial and antibiofilm activities were determined by the red/green ratios (R/G values) of 7-day-old mature biofilms photographed with quantitative light-induced fluorescence-digital, the number of aciduric bacterial colony-forming units (CFUs) within each biofilm, and the absorbance of bacterial suspensions. One-way and repeated-measures analysis of variance were performed to compare differences among the three solutions. R/G values were lowest in the 0.12% CHX group, but not significantly differ from the 5% CEON group. The number of CFUs and absorbance were lowest in the 5% CEON group. This study showed that nanoemulsified CEO inhibited the maturation of multi-species oral biofilms and the growth of oral microorganisms in biofilms, including aciduric bacteria that cause dental caries.

Antagonistic activity of strains of lactic acid bacteria isolated from Carpathian cheese

A promising area for improving probiotics is the search for new sources of strains and the development of complex preparations which would include different types of bacterial cultures that complement each other. Sources of selection may be traditional dairy products, in particular, cheeses made from raw milk. Wild strains can be endowed with antibacterial properties. The antagonistic action of lactic acid bacteria (LAB) has long attracted the attention of researchers and scientists. The aim of the study was to investigate the antagonistic activity against pathogenic and opportunistic microorganisms of LAB strains isolated from traditional Carpathian cheese. Three samples of cheese were selected for the research – one sample of brynza and budz (brynza before salting), made in the highlands of the Carpathians, and one sample of budz, made in the foothills. LAB were identified using classic microbiological and modern molecular genetic methods (RAPD-PCR, RFLP-PCR, 16S rRNA gene sequencing). The objects of our studies were five strains of LAB: Lactococcus lactis IMAU32258, L. garvieae JB2826472, Enterococcus durans FMA8, E. faecium L3-23, E. faecium IMAU9421. Technological parameters such as acid-forming activity of milk fermentation, resistance to high concentrations of NaCl and temperature optimums of cultivation were taken as the main criteria for assessing the suitability of LAB for inclusion in fermentation preparations. Antagonistic activity was determined by agar diffusion (agar well method) and optic density of test cultures using a Multiscan FC microplate reader (Thermo scientifiс, USA) at the wave of 620 nm. There were four reference strains of pathogenic and opportunistic microorganisms were test cultures: Listeria monocytogenes PCM 2191, Staphylococcus aureus PCM 458, Escherichia coli PCM 2208, Salmonella typhimurium PCM 2182. Strains of the test cultures were received from the collection of microorganisms of the Institute of Biology and Biotechnology the (University of Rzeszów, Poland). According to the ability of LAB strains to form lactic acid, L. lactis IMAU32258 was the best acid-forming agent with an acid-forming energy of 94 °T. E. faecium was characterized by moderate levels of active and titratable acidity. Less pronounced acid-forming ability was determined for the species E. durans and L. garvieae. Cultures of the genus E. faecium, L. garvieae and E. durans were the most resistant to high concentrations of NaCl (6.5%). Regarding temperature optimums, we found that strains of E. faecium and E. durans species grew both at temperatures of 10, 15 and 45 °C, whereas no growth of L. lactis IMAU32258 and L. garvieae JB282647 2 was observed at 45 °C. Among the studied bacteria, the strains of E. durans FMA8 and E. faecium L3-23 were characterized by the highest antagonistic activity in producing the largest zones of growth inhibition and optic density of pathogenic and opportunistic microorganisms. The strain L. garvieae JB282647 2 exhibited the lowest level of antagonistic activity against pathogenic and opportunistic microorganisms.

Probiotic Effects of Lactobacillus paracasei 28.4 to Inhibit Streptococcus mutans in a Gellan-Based Formulation

Streptococcus mutans is considered to be a major bacterium involved in dental caries, and the control of virulence mechanisms is fundamental to prevent disease. Probiotics present a promising preventive method; however, the use of probiotics requires its incorporation into delivery materials to facilitate oral colonization. Thus, we performed a comprehensive study examining preventive effects of Lactobacillus paracasei 28.4-enriched gellan hydrogel materials to inhibit S. mutans in planktonic and biofilm states, addressing its influence in the production of extracellular polysaccharides (EPS) and altered gene expression of several cariogenic virulence factors. L. paracasei 28.4, a strain isolated from the oral cavity of a caries-free individual, was incorporated in three gellan hydrogels (0.5%, 0.75%, and 1% w/v). The pretreatment with probiotic-gellan formulations provided a release of L. paracasei cells over 24 h that was sufficient to inhibit the planktonic growth of S. mutans, independent of the gellan concentrations and pH variations. This pretreatment also had inhibitory activity against S. mutans biofilms, exhibiting a reduction of 0.57 to 1.54 log₁₀ in CFU/mL (p < 0.0001) and a decrease of 68.8 to 71.3% in total biomass (p < 0.0001) compared with the control group. These inhibitory effects were associated with the decreased production of EPS by 80% (p < 0.0001) and the downregulation of luxS, brpA, gbpB, and gtfB genes. The gellan formulation containing L. paracasei 28.4 exhibited probiotic effects for preventing S. mutans growth, biofilm formation, and production of cariogenic factors to suggest possible use in tooth decay prevention.

Inhibition of Streptococcus mutans Biofilm Formation and Virulence by Lactobacillus plantarum K41 Isolated From Traditional Sichuan Pickles

Among cariogenic microbes, Streptococcus mutans is considered a major etiological pathogen of dental caries. Lactobacilli strains have been promoted as possible probiotic agents against S. mutans, although the inhibitory effect of Lactobacilli on caries has not yet been properly addressed. The objective of this study was to screen Lactobacillus strains found in traditional Sichuan pickles and to evaluate their antagonistic properties against S. mutans in vitro and in vivo. In the current study, we analyzed 54 Lactobacillus strains isolated from pickles and found that strain L. plantarum K41 showed the highest inhibitory effect on S. mutans growth as well as on the formation of exopolysaccharides (EPS) and biofilm in vitro. Scanning electron microscopy (SEM) and confocal laser scanning microscope (CLSM) revealed the reduction of both EPS and of the network-like structure in S. mutans biofilm when these bacteria were co-cultured with strain L. plantarum K41. Furthermore, when rats were treated with strain L. plantarum K41, there was a significant reduction in the incidence and severity of dental caries. Due to K41's origin in a high salinity environment, it showed a high tolerance to acids and salts. This may give this strain an advantage in harsh oral conditions. Results showed that L. plantarum K41 isolated from traditional Sichuan pickles effectively inhibited S. mutans biofilm formation and thus possesses a potential inhibitory effect on dental caries in vivo.

Antibacterial Activity of Lactobacillus Strains Isolated from Mongolian Yogurt against Gardnerella vaginalis

Worldwide interest in the use of functional foods containing probiotic bacteria such as Lactobacillus and Bifidobacterium for health promotion and disease prevention has increased significantly. Probiotics have demonstrated beneficial properties including strengthening the body's natural defense system, inhibiting the growth of pathogenic bacteria, and regulating mental activity, but their effects on the human vagina have not been fully elucidated. The primary purpose of our study was to isolate Lactobacillus strains from old yogurt, a traditional dairy product, and investigate their probiotic potential with respect to the human vaginal system. Four Lactobacillus plantarum (L. plantarum) strains, named ZX1, ZX2, ZX27, and ZX69, were isolated from the yogurt samples. Simultaneously, we used a commercial Lactobacillus strain (Lactobacillus delbrueckii DM8909) as a control strain. We tested the antimicrobial activity of Lactobacillus isolates against Escherichia coli and Gardnerella vaginalis by agar spot and well diffusion tests. Then, we tested the antibiotic susceptibility of the 5 strains by using the minimal inhibitory concentration method. We attempted to detect possible bacteriocin genes by PCR sequencing technique. Using a chemically defined medium simulating genital tract secretions, we found that the selected Lactobacillus strains could alter the expression of known virulence genes in Gardnerella vaginalis. Bacteriocins derived from these isolated strains had potent antibacterial activity against G. vaginalis and E. coli, with the most effective activity observed in the case of ZX27. In addition, all strains including the L. delbrueckii DM8909 were positive for the presence of the plantaricin cluster of genes described in L. plantarum C11. The tested stains possessed the pln gene indicating that one of the antibacterial agents was plantaricin. We assume that the production of antimicrobial substances such as bacteriocins induce G. vaginalis to upregulate antimicrobial resistance genes. The new isolated strains have bacteriocin-related genes and can change the antimicrobial resistance gene transcription of G. vaginalis.

The Battle of Probiotics and Their Derivatives Against Biofilms

Biofilm-related infections have been a major clinical problem and include chronic infections, device-related infections and malfunction of medical devices. Since biofilms are not fully available for the human immune system and antibiotics, they are difficult to eradicate and control; therefore, imposing a global threat to human health. There have been avenues to tackle biofilms largely based on the disruption of their adhesion and maturation. Nowadays, the use of probiotics and their derivatives has gained a growing interest in battling against pathogenic biofilms. In the present review, we have a close look at probiotics with the ultimate objective of inhibiting biofilm formation and maturation. Overall, insights into the mechanisms by which probiotics and their derivatives can be used in the management of biofilm infections would be warranted.

El-Seedi H. The Many Faces of Kefir Fermented Dairy Products: Quality Characteristics, Flavour Chemistry, Nutritional Value, Health Benefits, and Safety

Kefir is a dairy product that can be prepared from different milk types, such as goat, buffalo, sheep, camel, or cow via microbial fermentation (inoculating milk with kefir grains). As such, kefir contains various bacteria and yeasts which influence its chemical and sensory characteristics. A mixture of two kinds of milk promotes kefir sensory and rheological properties aside from improving its nutritional value. Additives such as inulin can also enrich kefir's health qualities and organoleptic characters. Several metabolic products are generated during kefir production and account for its distinct flavour and aroma: Lactic acid, ethanol, carbon dioxide, and aroma compounds such as acetoin and acetaldehyde. During the storage process, microbiological, physicochemical, and sensory characteristics of kefir can further undergo changes, some of which improve its shelf life. Kefir exhibits many health benefits owing to its antimicrobial, anticancer, gastrointestinal tract effects, gut microbiota modulation and anti-diabetic effects. The current review presents the state of the art relating to the role of probiotics, prebiotics, additives, and different manufacturing practices in the context of kefir's physicochemical, sensory, and chemical properties. A review of kefir's many nutritional and health benefits, underlying chemistry and limitations for usage is presented.

Organic acids and 2,4-Di-tert-butylphenol: major compounds of Weissella confusa WM36 cell-free supernatant against growth, survival and virulence of Salmonella Typhi

Background

Salmonella Typhi (S. Typhi), the causative agent of typhoid fever, causes serious systemic disease in humans. Antibiotic treatment is required for the S. Typhi infection, while the inappropriate use of antibiotics causes increased drug-resistant S. Typhi. Hence, alternative therapies through non-antibiotic approaches are urgently needed. The use of beneficial lactic acid bacterium and/or its metabolites to control typhoid fever represent a promising approach, as it may exert protective actions through various mechanisms.

Method

In this study, the cell-free culture supernatant (CFCS) of Weissella confusa WM36 was evaluated via the antibacterial activity, and its metabolites were identified. In addition, the effects of CFCS on Salmonella virulence behaviors were also investigated.

Result

Based on strong inhibition the growth of S. Typhi DMST 22842, organic acids (lactic acid and acetic acid) and 2,4-Di-tert-butylphenol (2,4 DTBP), were the main antibacterial metabolites presented in CFCS of strain WM36. Minimum inhibitory concentration (MIC) at 40% WM36–CFCS dramatically reduced the S. Typhi population to more than 99.99% at 4 h and completely inhibited biofilm formation, while sub-MIC at 20% (v/v) and MIC could reduce 100% of motility. Additionally, sub-MIC at only 10% (v/v) WM36–CFCS did down-regulate the expression of virulence genes which are responsible for the type-III secretion system, effector proteins, and quorum sensing system in this pathogen.

Conclusion

W. confusa WM36 and its metabolites are shown to be a promising candidates, and an effective approach against typhoid Salmonella burden.

Investigation of physicochemical composition and microbial communities in traditionally fermented vrum from Inner Mongolia

Mongolian traditionally fermented vrum is known for its functional characteristics, and indigenous microbial flora plays a critical role in its natural fermentation. However, studies of traditionally fermented vrum are still rare. In this study, we investigated the artisanal production of traditionally fermented vrum from Inner Mongolia. In general, its physicochemical composition was characterized by 34.5 ± 8% moisture, 44.9 ± 12.1% fat, 10.6 ± 3.2% protein, and 210 ± 102°T. The total lactic acid bacteria and yeast counts ranged from 50 to 2.8 × 10⁸ cfu/g and from 0 to 1.1 × 10⁶ cfu/g, respectively. We studied bacterial and fungal community structures in 9 fermented vrum; we identified 5 bacterial phyla represented by 11 genera (an average relative abundance >1%) and 8 species (>1%), and 3 fungal phyla represented by 8 genera (>1%) and 8 species (>1%). Relative abundance values showed that Lactococcus and Lactobacillus were the most common bacterial genera, and Dipodascus was the predominant fungal genus. This scientific investigation of the nutritional components, microbial counts, and community profiles in Mongolian traditionally fermented vrum could help to develop future functional biomaterials and probiotics.

Inhibition of Streptococcus mutans by a commercial yogurt drink

Background/Purpose

Studies have been focused on using probiotics to prevent caries. The lactobacillus probiotic bacteria in Yakult^® (LcY) has been shown to inhibit the growth or biofilm formation of Streptococcus mutans. However, sucrose in Yakult^® raised concerns. The purpose of this study was to determine effects of Yakult^® on the growth and adhesion of S. mutans.

Materials and methods

S. mutans was grown in serial diluted Yakult^®, filtered Yakult^® or 20% heated Yakult^®. S. mutans was co-cultured with LcY in media with or without diluted filtered Yakult^®, or in LcY grown in media with or without sugars. Colony forming units and pH values of bacterial cultures were determined. SYTO 9-stained adhered bacteria were observed.

Results

Yakult^® inhibited the growth of S. mutans. Filtering or heating Yakult^® reduced its inhibitory ability against S. mutans. The inhibitory effect of LcY against S. mutans was enhanced when cultured in the presence of 20% filtered Yakult^®. LcY cultured in sucrose media for 24 h inhibited the growth of S. mutans, but this effect was less evident when LcY was grown for 48 h. LcY grown in glucose or lactose media similarly reduced S. mutans growth. Culturing S. mutans with LcY grown in sucrose or glucose media reduced bacterial adhesion. However, co-culturing S. mutans with LcY grown in the lactose media did not decrease bacterial adhesion.

Conclusion

Yakult^® and its probiotic content may inhibit S. mutans growth and the effect may be moderated by the type of sugar added for LcY cultivation.

Health promoting activities of probiotics

In recent years, probiotics have received increasing attention and become one type of popular functional food because of their many biological functions. Among these desirable biological functions, the immune regulation, antioxidative activities, and antimicrobial effects are essential properties to maintain host health. Probiotics can regulate the immune system and improve the antioxidative system by producing microbial components and metabolites. Meanwhile, probiotics also possess antimicrobial abilities owing to their competition for nutrient requirements and mucus adherence, reducing pathogenic toxins, producing antimicrobial metabolites (short-chain fatty acids, bacteriocins, reuterin, linoleic acid, and secondary bile acids) and enhancing intestinal, or systemic immunity. Therefore, probiotics could be used to alleviate heavy metal toxicity and metabolic disorders by improving immunity, the antioxidative system, and intestinal micro-environment. This comprehensive review mainly highlights the potential health promoting activities of probiotics based on their antioxidative, antimicrobial, and immune regulatory effects. PRACTICAL APPLICATIONS: The antioxidative defense and the immune system are essential to maintain human health. However, many factors may result in microbial dysbiosis in the gut, which subsequently leads to pathogenic expansion, oxidative stress, and inflammatory responses. Therefore, it is important to explore beneficial foods to prevent or suppress these abnormal responses. Successful application of probiotics in the functional foods has attracted increasing attention due to their immune regulatory, antioxidative, and antimicrobial properties. The aim of this review is to introduce immune regulatory antioxidative and antimicrobial effects of probiotics, which provides some basic theories for scientific research and development of potential functional foods.

Analysis of Health Benefits Conferred by Lactobacillus Species from Kefir

Lactobacilli are among the most common microorganisms found in kefir; a traditional fermented milk beverage produced locally in many locations around the world. Kefir has been associated with a wide range of purported health benefits; such as antimicrobial activity; cholesterol metabolism; immunomodulation; anti-oxidative effects; anti-diabetic effects; anti-allergenic effects; and tumor suppression. This review critically examines and assesses these claimed benefits and mechanisms with regard to particular Lactobacillus species and/or strains that have been derived from kefir; as well as detailing further potential avenues for experimentation.