Autoaggregation Ability Research Articles

Probiotic properties and antimicrobial evaluation of silymarin-enriched Lactobacillus bacteria isolated from traditional curd

Nowadays, the increasing use of medicinal plants in the treatment and prevention of diseases has attracted the attention of researchers. The aim of this work was to investigate the probiotic properties and antibacterial and antifungal activity of silymarin-enriched Lactobacillus bacteria against several important pathogenic bacteria and also Aspergillus flavus as one of the harmful molds in the food and health industries. For this purpose, 52 g-positive and catalase-negative bacteria were isolated from 60 traditional curd samples from Ilam province. Five of the 52 bacterial strains had more than 90% viability in high bile salt and acidic conditions and were selected for further investigation. The five strains with positive results showed good hydrophobicity (≥ 50.30%), auto-aggregation (≥ 53.70%), coaggregation (≥ 28.20%), and high cholesterol removal ability (from 09.20 to 67.20%) and therefore can be considered potential probiotics. The tested strains displayed acceptable antibacterial and antifungal activity against all 12 pathogenic bacteria and A. flavus. Also, the results of the simultaneous antifungal activity of probiotic strains and silymarin showed that the combination of silymarin and probiotics has a significantly better (P < 0.05) antifungal effect than the control group or the probiotic groups alone. Interestingly, in addition to the Limosilactobacillus fermentum C3 strain, the Limosilactobacillus fermentum C18 and Lactiplantibacillus pentosus C20 strains also had significant inhibitory effects against A. flavus when used with silymarin extract in methanol. Meanwhile, silymarin extract in DMSO and PEG increased the antagonistic activity of all five potential probiotic strains.

Potential probiotic characterization of lactic acid bacteria isolated from Duimaj, an Iranian traditional snack food, using biochemical, molecular and computational approaches

The aim of this study was isolation and identification of lactic acid bacteria from Duimaj (an Iranian traditional snack food) and in vitro characterization of probiotic features. In total, thirty presumptive LAB colonies were surveyed, of which 22 exhibited high rates of survival in artificial gastrointestinal fluids, which were found to belong to Lactobacillus, Enterococcus, and Pediococcus genera based on 16 S-rRNA gene sequence. The selected strains had strong antagonistic effects, with auto-aggregation abilities ranging from 26.52 to 81.50% and co-aggregation capacity up to 88.33 and 80.14% with E. coli and S. aureus, respectively. Moreover, the cell surface hydrophobicity of strains ranged from 31.06 to 85.62%. Results indicated that nine isolated LAB harbored the cholesterol assimilation rates greater than 30%. Moreover, none of the selected strains showed hemolytic activity. Among the isolates, five strains were negative for all nine tested virulent genes, and exhibited favorable adhesion percentage to human intestinal epithelial cells ranging from 31.76 to 52.37. Hence, naturally occurring Lactiplantibacillus plantarum and Lactiplantibacillus pentosus isolated from Duimaj were proposed as suitable probiotic candidates for use in functional foods.

Evaluation of probiotic and anti-inflammatory properties of bacteriocinogenic Pediococcus acidilactici HW01 and Leuconostoc citreum HW02 from malted barley

BackgroundBacteriocins are peptides with antibacterial properties that are released by lactic acid bacteria and affect genetically closely related bacteria. Settled bacteriocin-producing probiotics in the GI tract may contribute to bacteriocin formation, which can lead to pathogen inhibition and immune system regulation. The purpose of this study is to evaluate the probiotic capabilities of bacteriocin-producing LAB isolated from malted barley, Pediococcus acidilactici HW01, and Leuconostoc citreum HW02.ResultsBoth strains could survive in harsh GI conditions such as low pH, bile salt, pepsin, and lysozyme. Furthermore, exhibited non-haemolytic activity and tetracycline and erythromycin susceptibilities. In vitro adhesion of HW01 and HW02 strains to HT-29 cells was 76.28 and 75.99%, respectively. Auto-aggregation ability of HW01 and HW02 was about 14%, but their ability to aggregate with pathogens (Escherichia coli, Salmonella enterica ser. Typhimurium, Staphylococcus aureus and Listeria monocytogenes) ranged from 32.0% to 43.5%. Regarding the anti-inflammatory effect, heat-killed bacteriocin-producing strains suppressed the mRNA expression levels of cytokines and chemokines in RAW 264.7 macrophages induced by LPS (P < 0.005).ConclusionsBacteriocin-producing P. acidilactici HW01 and Leu. citreum HW02 may be good probiotic candidates.Graphical

Characterization of Lactic Acid Bacteria Strains Isolated from Algerian Honeybee and Honey and Exploration of Their Potential Probiotic and Functional Features for Human Use.

Using culture enrichment methods, 100 strains of bacilli of lactic acid bacteria (LAB) were isolated from honeybee Apis mellifera intermissa and fresh honey, collected from apiaries located in the north-east of Algeria. Amongst all of the isolated LAB, 19 selected strains were closely affiliated to four species-Fructobacillus fructosus (10), Apilactobacillus kunkeei (5), Lactobacillus kimbladii and/or Lactobacillus kullabergensis (4)-using phylogenetic and phenotypic approaches. The in vitro probiotic characteristics (simulated gastrointestinal fluids tolerance, autoaggregation and hydrophobicity abilities, antimicrobial activity and cholesterol reduction) and safety properties (hemolytic activity, antibiotic resistance and absence of biogenic amines) were evaluated. The results indicated that some strains showed promising potential probiotic properties. In addition, neither hemolytic activity nor biogenic amines were produced. The carbohydrate fermentation test (API 50 CHL) revealed that the strains could efficiently use a broad range of carbohydrates; additionally, four strains belonging to Apilactobacillus kunkeei and Fructobacillus fructosus were found to be exopolysaccharides (EPS) producers. This study demonstrates the honeybee Apis mellifera intermissa and one of her products as a reservoir for novel LAB with potential probiotic features, suggesting suitability for promoting host health.

Co-Aggregative Effect of Probiotics Bacteria against Diarrheal Causative Bacteria.

Probiotics have been used for over a century to prevent and treat diseases. They can reduce the effects of gastroenteritis and are now used to treat acute diarrhea. This study aimed to evaluate the co-aggregative effects of probiotics bacteria against diarrheal causative bacteria. For this purpose, 11 isolates of probiotic bacteria were used in the current study, including three Lactobacillus plantarum, one Lactobacillus gasseri, two Lactobacillus fermentum, three Lactobacillus acidophilus, and two Lactococcus garvieae isolates. All isolates were tested for antibiotic susceptibility, autoaggregation ability, adhesion ability, antibacterial activity, acid tolerance, and bile salts tolerance. The results showed that most of them had the ability to autoaggregate after 4 h, with the highest percentage of 57.14% for L. fermentum. For the antibiotic susceptibility test, all the isolates showed resistance against trimethoprim/sulfamethoxazole, except one isolate. Moreover, all the isolates, except one, were susceptible to both vancomycin and tetracycline. All tested isolates had adhesion ability with different survival rates, which reached 34.57% for L. plantarum in acidic conditions. Besides, the highest survival rate was 85.17%, which belonged to L. garvieae, for bile salt tolerance. Probiotic isolates had an antibacterial effect against diarrhea-causative bacteria with an inhibition diameter of 17-49 mm for different Lactobacillus spp. and Lactococcus spp. isolates. Furthermore, the co-aggregation ability of probiotic isolates against diarrhea-causative bacteria was studied, and results showed that probiotic isolates had a co-aggregative effect against diarrhea-causative bacteria, Escherichia coli, Shigella sonnei, and Providencia alcalifaciens, after 24 h of incubation. The highest co-aggregative effect of probiotics isolates belonged to L. fermentum and L. acidophilus against P. alcalifaciens with a co-aggregation percentage of 100%, while the lowest co-aggregation rate was 14.29% against E. coli. The findings revealed the probiotic properties and co-aggregative effects of probiotic bacteria against diarrhea-causative bacteria.

Effect of prebiotic supplementation on the low-temperature storage stability and in vitro gastrointestinal tolerance of Bifidobacterium breve and Bifidobacterium longum in lactose and sucrose systems

The objective of this study was to investigate the effect of fructooligosaccharides (FOS) and inulin supplementation on the stability of Bifidobacterium breve and Bifidobacterium longum grown in lactose and sucrose systems over 12-week low-temperature storage at 4 °C. FOS and inulin supplementation in the lactose and sucrose systems improved the low-temperature storage stability of B. breve and B. longum. On week 12, the highest lactic (29.7 ± 0.7%) and acetic acid (28.7 ± 1.3%) concentrations were observed in B. breve in 2% lactose with 3% inulin supplementation. In week 12, B. breve auto-aggregation rate and hydrophobicity significantly increased in 2% lactose with 3% inulin supplementation than non-supplemented (2% lactose). At week 0, the co-aggregation of B. longum and B. breve with E. faecalis and E. coli significantly increased compared to non-supplemented media. However, as the storage week proceeded, the co-aggregation ability of B. longum and B. breve drastically declined. FOS and inulin supplementation in these sugar systems significantly improved hydrophobicity, auto-aggregation, and co-aggregation ability with Enterococcus faecalis and Escherichia coli compared to non-supplemented media. In addition, the increase in the bacterial survival rate in vitro gastrointestinal tolerance assay showed that FOS and inulin supplementation in these sugar systems improved the gastric-intestinal tolerance of B. breve and B. longum.

Bakteri Asam Laktat Kandidat Probiotik dari Susu Kuda Bima

Awareness of the role of healthy food has led to increased public interest in healthy food that has additional functions than as energy fulfillment. One form of the healthy foods is food that contains probiotics, so this study aims to select lactic acid bacteria from milk as probiotic candidates. Lactic acid bacteria isolates from goat, horse and buffalo milk in Indonesia were studied to find the best probiotic candidates out of 100 isolates. Parameters which are measured in this study included resistance to gastric acid, bile salts, aggregation, autoaggregation abilities, and sensitivity to antibiotics. One isolate from bima horse’s milk has the potency as a probiotic candidate. The bacterial isolate from Bima horse’s milk has the character of being resistant to acids, and bile salts, sensitive to the two antibiotics tested and can aggregate with Salmonella Thypimurium. From molecular identification, the selected Bima horse’s milk isolate has similarities with Lacticaseibacillus rhamnosus strain MG5511.

Design, Synthesis and Evaluation of a Series of Zinc(II) Complexes of Anthracene-Affixed Multifunctional Organic Assembly as Potential Antibacterial and Antibiofilm Agents against Methicillin-Resistant Staphylococcus aureus

A novel class of zinc(II)-based metal complexes, i.e., [Zn2(acdp)(μ-Cl)]·2H2O (1), [Zn2(acdp)(μ-NO3)]·2H2O (2), and [Zn2(acdp)(μ-O2CCF3)]·2H2O (3) (Cl- = chloride; NO3- = nitrate; CF3CO2- = trifluoroacetate) of anthracene-affixed multifunctional organic assembly, H3acdp (H3acdp = N,N'-bis[anthracene-2-ylmethyl]-N,N'-bis[carboxymethyl]-1,3-diaminopropan-2-ol), have emerged as promising antibacterial and antibiofilm agents in the domain of medicinal chemistry. Accordingly, complexes 1-3 were synthesized by utilizing H3acdp in combination with ZnCl2, Zn(NO3)2·6H2O, and Zn(CF3CO2)2·H2O respectively, in the presence of NaOH at ambient temperature. The complexation between H3acdp and Zn2+ was delineated by a combined approach of spectrophotometric and spectrofluorometric titration studies. The stoichiometry of acdp3-/Zn2+ in all three complexes is observed to be 1:2, as confirmed by spectrophotometric/spectrofluorometric titration data. Elemental analysis (C, H, N, Zn), molar conductance, FTIR, UV-vis, and thermoanalytical (TGA/DTA) data were effectively used to characterize these complexes. Besides, the structures of 1-3 were established by density functional theory (DFT) calculation using B3LYP/6-311G, specifying a self-assembled compact geometry with average Zn···Zn separation of 3.4629 Å. All three zinc complexes exhibited significantly high antibacterial and antibiofilm activity against methicillin-resistant Staphylococcus aureus (MRSA BAA1717). However, complex 1 showed a more recognizable activity than 2 and 3, with minimum inhibitory concentration (MIC) values of 200, 350, and 450 μg/mL, respectively. The antimicrobial activity was tested by employing the minimum inhibitory concentration (MIC) and time-kill assay. The crystal violet (CV) assay and microscopic study were performed to examine the antibiofilm activity. As observed, complexes 1-3 had an effect on the production of extracellular polymeric substance (EPS), biofilm cell-viability, and other virulence factors such as staphyloxanthin and hemolysin production, autoaggregation ability, and microbial cell-surface hydrophobicity. Reactive oxygen species (ROS) generated due to inhibition of staphyloxanthin production in response to 1-3 were also analyzed. Moreover, complexes 1-3 showed an ability to damage the bacterial cell membrane due to accumulation of ROS resulting in DNA leakage. In addition, complexes 1-3 displayed a synergistic/additive activity with a commercially available antibiotic drug, vancomycin, with enhanced antibacterial activity. On the whole, our investigation disclosed that complex 1 could be a promising drug lead and attract much attention to medicinal chemists compared to 2 and 3 from therapeutic aspects.

In vitro assessment for the probiotic potential of Pichia kudriavzevii.

It is of interest to isolate the probiotic yeast Pichia kudriavzevii based on its probiotic characteristics and enzyme production. The isolate was able to withstand high acid, bile concentration and showed a high viability. Additionally, it showed auto aggregation ability that increases with time and hydrophobicity with xylene. It was resistant to different antibiotics and showed no hemolytic activity. The isolate was also capable of producing phytase that can break down phytate. Overall, the characteristics of P. kudriavzevii suggest that it could potentially have probiotic properties, and its ability to produce phytase could also make it useful in feed and animal industries.

Evaluating the Probiotic Potential of Lactic Acid Bacteria Implicated in Natural Fermentation of Table Olives, cv. Cobrançosa.

The probiotic features of Lactiplantibacillus (L.) pentosus and L. paraplantarum strains, endogenous in Cobrançosa table olives from northeast Portugal, were assessed in terms of functional properties and health benefits. Fourteen lactic acid bacteria strains were compared with Lacticaseibacillus casei from a commercial brand of probiotic yoghurt and L. pentosus B281 from Greek probiotic table olives, in attempts to select strains with higher probiotic performances than those references. For functional properties, the i53 and i106 strains, respectively, exhibited: 22.2 ± 2.2% and 23.0 ± 2.2% for Caco-2 cell adhesion capacity; 21.6 ± 7.8% and 21.5 ± 1.4% for hydrophobicity; 93.0 ± 3.0% and 88.5 ± 4.5% for autoaggregation ability by 24 h of incubation; and ability to co-aggregate with selected pathogens-from 29 to 40% to Gram+ (e.g., Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212); and from 16 to 44% for Gram- (e.g., Escherichia coli ATCC 25922 and Salmonella enteritidis ATCC 25928). The strains proved to be resistant (i.e., halo zone ≤14 mm) to some antibiotics (e.g., vancomycin, ofloxacin, and streptomycin), but susceptible (i.e., halo zone ≥ 20 mm) to others (e.g., ampicillin and cephalothin). The strains exhibited health-beneficial enzymatic activity (such as acid phosphatase and naphthol-AS-BI-phosphohydrolase), but not health-harmful enzymatic activity (such as β-glucuronidase and N-acetyl-β-glucosaminidase). Additionally, the antioxidant activity and cholesterol assimilation features, respectively, of the strains were 19.6 ± 2.8% and 77.5 ± 0.5% for i53, and 19.6 ± 1.8% and 72.2 ± 0.9% for i106. This study indicated that the addition of L. pentosus strains i53 and/or i106 to Cobrançosa table olives is likely to enhance the added value of the final product, in view of the associated potential benefits upon human health.

Biofilm formation and auto-aggregation abilities of novel targeted aqua-probiotics

Background: The probiotics’ auto-aggregation and biofilm formation abilities have a significant role in the development of biotechnological processes.Objective: The aim of this study was to evaluate the biofilm formation and auto-aggregation abilities of novel, targeted aqua-probiotics isolated from aquatic organisms.Methods: The biofilm formation abilities of Lactobacillus delbrueckii str. UZ-1, Lactiplantibacillus plantarum str. R3, Lactococcus str. UZ-2, Enterococcus faecium str. R2, Pediococcus acidilactici str. N from the culture collection of the Microbiology of the Academy of Sciences of the Republic of Uzbekistan, Bacillus subtilis str. 1R, Bacillus amyloliquefaciens str. 4R and from the culture collection of the Southern Federal University of Russa and Lacticaseibacillus rhamnosus str. 1A and Enterococcus str. 9-3 from the culture collection of the Armenian National Agrarian University were assessed.Results: According to the investigations, the biofilm formation abilities of Lactobacillus delbrueckii str. UZ-1, Lactiplantibacillus plantarum str. R3, Lactococcus str. UZ-2, Enterococcus faecium str. R2, Pediococcus acidilactici str. N, Bacillus subtilis str. 1R, Bacillus amyloliquefaciens str. 4R, Bacillus amyloliquefaciens str. 5R, Lacticaseibacillus rhamnosus str. 1A and Enterococcus str. 9-3 were 0.119 ± 0.05D, 0.113 ± 0.065D, 0.196 ± 0.04D, 0.116 ± 0.01D, 0.152 ± 0.05D, 0.74 ± 0.15D, 2.621± 0.55D, 1.831 ± 0.45D, and 0.227 ± 0.04D and 0.483 ± 0.15D respectively. The highest rate of auto-aggregation was shown by Bacillus amyloliquefaciens str. 5R, and Bacillus amyloliquefaciens str. 4R was the strain with the highest ability to form biofilm. These two Bacillus strains are also distinguished by the highest DNA protective properties and relatively low antioxidant activity. Despite the fact that Bacillus amyloliquefaciens str. 5R showed the highest rate of auto-aggregation after 2 hours, this strain showed the lowest level of auto-aggregation among the studied strains after 24 hours. The Enterococcus str. 9-3 strain with the highest antioxidant activity showed 0.483 ± 0.15D biofilm formation ability.Conclusion: The novel targeted aquaprobiotics have distinct biofilm formation and aggregation properties, which are important to consider when planning appropriate biotechnological processes, requiring specific membrane properties of probiotics.Graphical Abstract: Membrane properties of novel targeted aquaprobiotics.Keywords: Lactobacilli, aqua-probiotic, antioxidant activity, biofilm formation, aggregation, Enterococcus str. 9-3

Phenotypic Traits and Probiotic Functions of Lactiplantibacillus plantarum Y42 in Planktonic and Biofilm Forms.

Bacteria in planktonic and biofilm forms exhibit different phenotypic properties. In this study, the phenotypic traits and probiotic functions of Lactiplantibacillus plantarum Y42 in planktonic and biofilm forms were assessed. After 36 h of static culture, scanning electron microscopy and confocal laser scanning microscopy showed that the L. plantarum Y42 bacterial cells contained interconnected adhesive matter on the surface, forming a ~18 μm layer of dense biofilms. The surface properties of L. plantarum Y42 in biofilm form, including autoaggregation ability, hydrophobicity, acid-base charge, and adhesiveness, were all higher than those in the planktonic form. Biofilm L. plantarum Y42 showed a higher tolerance to adverse environmental conditions and a higher survival rate, enzymatic activity, and integrity after vacuum lyophilization. And biofilm L. plantarum Y42 had higher adhesion to human enterocyte HT-29 cell monolayers, inhibited the expressions of proinflammatory factors IL-6 and TNF-α, and promoted the expressions of the anti-inflammatory factor IL-10 and barrier proteins Claudin-1 and Occludin. In addition, L. plantarum Y42 in biofilm form can inhibit the adhesion and invasion of Listeria monocytogenes ATCC 19115 to HT-29 cell monolayers and is more effective in relieving the inflammatory reactions and injuries of HT-29 cells caused by L. monocytogenes ATCC 19115. In conclusion, L. plantarum Y42 in biofilm form exhibited better probiotic functions compared to that in planktonic form. This indicated that L. plantarum Y42 can form biofilms to enhance its probiotic functions, which provided a theoretical basis for better development and utilization of L. plantarum Y42.

Evaluation of the Probiotic Properties of Lacticaseibacillus casei 431® Isolated from Food for Special Medical Purposes§.

Increasing awareness of the importance of nutrition in health promotion and disease prevention has driven to the development of foods for special medical purposes (FSMPs). In this study, the probiotic strain Lacticaseibacillus paracasei ssp. paracasei (Lacticaseibacillus casei 431®) was incorporated into FSMPs to develop an innovative product. The aim was to investigate the influence of the FSMP matrix on the specific probiotic properties of L. casei 431® in vitro. A series of in vitro experiments were performed as part of the probiotic approach. After evaluation of antibiotic susceptibility profiles, functional properties such as survival under simulated gastrointestinal tract (GIT) conditions, bile salt deconjugation activities, cholesterol assimilation, antagonistic activity against spoilage bacteria and adhesion to Caco-2 cell line monolayers and extracellular matrix proteins were investigated. The L. casei 431® strain, both the lyophilised strain and the strain isolated from the FSMP matrix, effectively survived the simulated adverse gastrointestinal conditions without significant effects of the food matrix. The effect of the FSMP matrix on the deconjugation activity of the bile salts of L. casei 431® was minimal; however, cholesterol assimilation was increased by 16.4 %. L. casei 431® had antibacterial activity against related lactic acid bacteria regardless of whether it was used in FSMPs or not. Conversely, the probiotic strain isolated from FSMP matrix had significantly higher inhibitory activity against six potential pathogens than the lyophilised culture. The autoaggregation ability of the L. casei 431® cells was not affected by the FSMP matrix. The adhesion of L. casei 431® bacterial cells to the extracellular matrix proteins was reduced after treatment with proteinase K, with the highest adhesion observed to laminin. The adhesion of L. casei 431® reduced the binding of E. coli 3014 by 1.81 log units and the binding of S. Typhimurium FP1 to Caco-2 cell lines by 1.85 log units, suggesting the potential for competitive exclusion of these pathogens. The results support the positive effect of the FSMP matrix on the specific probiotic properties of L. casei 431®, such as antibacterial activity, bile salt deconjugation and cholesterol assimilation, while the incorporation of this probiotic strain adds functional value to the FSMPs. The synergistic effect achieved by the joint application of L. casei 431® and innovative FSMP matrix contributed to the development of the novel formulation of an improved functional food product with added value.

Antimicrobial and immunoregulatory effects of Lactobacillus delbrueckii 45E against genitourinary pathogens

BackgroundLactobacilli are essential microbiota that maintain a healthy, balanced vaginal environment. Vaginitis is a common infection in women during their reproductive years. Many factors are associated with vaginitis; one of them is the imbalance of microbiota in the vaginal environment. This study aimed to evaluate the antimicrobial properties of Lactobacillus delbrueckii 45E (Ld45E) against several species of bacteria, namely, Group B Streptococcus (GBS), Escherichia coli, Klebsiella spp., and Candida parapsilosis, as well as to determine the concentration of interleukin-17 (IL-17) in the presence of Ld45E.MethodsThe probiotic characteristics of Ld45E were evaluated by examining its morphology, pH tolerance, adhesive ability onto HeLa cells, hemolytic activity, antibiotic susceptibility, and autoaggregation ability. Then, the antimicrobial activity of Ld45E was determined using Ld45E culture, cell-free supernatant, and crude bacteriocin solution. Co-aggregation and competition ability assays against various pathogens were conducted. The immunoregulatory effects of Ld45E were analyzed by measuring the proinflammatory cytokine IL-17. A p-value less than 0.05 was considered statistical significance.ResultsLd45E is 3–5 mm in diameter and round with a flat-shaped colony. pH 4 and 4.5 were the most favorable range for Ld45E growth within 12 h of incubation. Ld45E showed a strong adhesion ability onto HeLa cells (86%) and negative hemolytic activities. Ld45E was also sensitive to ceftriaxone, cefuroxime, ciprofloxacin, and doxycycline. We found that it had a good autoaggregation ability of 80%. Regarding antagonistic properties, Ld45E culture showed strong antimicrobial activity against GBS, E. coli, and Klebsiella spp. but only a moderate effect on C. parapsilosis. Cell-free supernatant of Ld45E exerted the most potent inhibitory effects at 40 °C against all genital pathogens, whereas bacteriocin showed a robust inhibition at 37 °C and 40 °C. The highest co-aggregation affinity was observed with GBS (81%) and E. coli (40%). Competition ability against the adhesion of GBS (80%), E. coli (76%), Klebsiella (72%), and C. parapsilosis (58%) was found. Ld45E was able to reduce the induction of the proinflammatory protein IL-17.ConclusionsLd45E possessed antimicrobial and immunoregulatory properties, with better cell-on-cell activity than supernatant activity. Thus, Ld45E is a potential probiotic candidate for adjunct therapy to address vaginal infections.

Promising Probiotic Properties of the Yeasts Isolated from Rabilé, a Traditionally Fermented Beer Produced in Burkina Faso.

In recent years, research on yeasts as probiotics has gained more and more interest, which will allow the development of "new" products in the probiotics market. In this context, seventeen yeast strains isolated from Rabilé, a traditional beer produced in Burkina Faso, were assessed for their probiotic attributes. The yeast identification was performed by molecular methods, including PCR-RFLP and 5.8S-ITS region sequencing. Saccharomyces cerevisiae (14 strains) was the predominantly identified species, followed by Pichia kudriavzevii (2 strains) and Rhodotorula mucilaginosa (1 strain). Except for R. mucilaginosa, all yeast strains grew well at human temperature. The yeast strains showed high resistance when they were exposed to simulated gastrointestinal conditions. Auto-aggregation ability was between 70.20 ± 10.53% and 91.82 ± 1.96%, while co-aggregation with E. coli ranged from 24.92 ± 3.96% to 80.68 ± 9.53% and with S. enterica serovar Typhimurium from 40.89 ± 8.18% to 74.06 ± 7.94%. Furthermore, the hydrophobicity of isolated strains toward n-hexane was in the range from 43.17 ± 5.07% to 70.73 ± 2.42%. All yeast strains displayed high antioxidant capabilities, and the strains did not show hemolysis halos, such that they can be considered safe. Additionally, S. cerevisiae strains strongly inhibited the growth of foodborne pathogens. This is the first preliminary study to identify and characterize the yeast strains isolated from Rabilé with interesting probiotic properties.

Proteomic analysis reveals the non-coding small RNA Qrr5 influences autoaggregation and growth competition in Vibrio parahaemolyticus

Vibrio parahaemolyticus, a sea-born bacterial pathogen, is a primary inducement of food-borne gastroenteritis. Previous studies have shown that non-coding small RNA plays a vital role in the regulation of multiple biological processes in pathogenic bacteria, especially autoaggregation and growth competition. However, the inherent mechanisms have not yet to be fully understood. As important regulators in Vibrios, the involvement of Qrr sRNAs in V. parahaemolyticus is largely unknown. Here, we carried out the Qrr5 deletion mutant and utilized a proteomic method to describe global proteomic alterations in response to Qrr5 deletion. A total of 297 significantly expressed proteins were determined between the Qrr5 deletion mutant and wild-type strain, among which 137 proteins were upregulated and 160 proteins were downregulated. The upregulated proteins principally participated in membrane transporters and signal transcription, while the downregulated proteins participated in the two-component system and transcription factor binding. Notably, transcriptional regulator LysR, outer membrane protein OmpA, and conjugal transfer protein TraA-related proteins were upregulated, causing the promotion of autoaggregation ability and growth competition ability against E. coli. This study provides insights into the regulatory network of sRNA in this bacterium, which will facilitate further explorations of important biological processes in pathogenic bacteria. SignificancesRNA Qrr5 is an important regulator involved in bacterial multiple physiological processes, including auto-aggregation and growth competition among food-borne pathogens Vibrio parahaemolyticus. Here, utilizing a TMT-labeling proteomic approach, we identified 137 proteins were upregulated and 160 proteins were downregulated between the Qrr5 deletion mutant and wild-type strain. The upregulated proteins were involved in membrane transporters and signal transcription, while downregulated proteins were involved in the two-component system and transcription factor binding. Moreover, the LysR, OmpA, and TraA proteins were significantly upregulated, causing the promotion of autoaggregation and commensal growth competition ability. The mechanism of how Qrr5 regulates the targeted genes remains unclarified and need great efforts to explore.

Fish Probiotics: Cell Surface Properties of Fish Intestinal Lactobacilli and Escherichia coli

The properties of intestinal bacteria/probiotics, such as cell surface hydrophobicity (CSH), auto-aggregation, and biofilm formation ability, play an important role in shaping the relationship between the bacteria and the host. The current study aimed to investigate the cell surface properties of fish intestinal bacteria and probiotics. Microbial adhesion to hydrocarbons was tested according to Kos and coauthors. The aggregation abilities of the investigated strains were studied as described by Collado and coauthors. The ability of bacterial isolates to form a biofilm was determined by performing a qualitative analysis using crystal violet staining based on the attachment of bacteria to polystyrene. These studies prove that bacterial cell surface hydrophobicity (CSH) is associated with the growth medium, and the effect of the growth medium on CSH is species-specific and likely also strain-specific. Isolates of intestinal lactobacilli from fish (Salmo ischchan) differed from isolates of non-fish/shrimp origin in the relationship between auto-aggregation and biofilm formation. Average CSH levels for fish lactobacilli and E. coli might were lower compared to those of non-fish origin, which may affect the efficiency of non-fish probiotics use in fisheries due to the peculiarities of the hosts' aquatic lifestyles.

Evaluation of novel isolates of Lacticaseibacillus rhamnosus Probio-M9 derived through space mutagenesis

This study evaluated the growth and probiotic properties of Probio-M9 after exposure to the environment of space. Probio-M9 has excellent probiotic properties. As a rapidly developed new cutting-edge technology, space mutagenesis can confer potentially desirable properties to novel isolates. In this study, three novel isolates (HA-R7970-29, HG-R7970-18, HG-R7970-29) mutated from Probio-M9 in space, had significantly higher growth characteristics than the original Probio-M9. Antibacterial properties, auto aggregation ability, cell surface hydrophobicity and antioxidant activity of the three mutagenic isolates were evaluated. The results showed that Probio-M9 remained stable after mutagenesis, and the mutant strains could effectively inhibit the growth of six common pathogenic bacteria. The mutated isolates showed strong auto aggregation ability (49.3%–76.5%, 24h) and cell surface hydrophobicity (25.7%–43.0%); HA-R7970-29 showed significantly higher auto aggregation ability and cell surface hydrophobicity than HG-R7970-18 and HG-R7970-29 (P < 0.05). In addition, the supernatants and bacterial suspensions of the three mutated isolates had strong antioxidant activities. Genomic analysis identified genes associated with bacteriocin, adhesion properties and antioxidant activity and probiotic features at the genetic level. Mutated isolates not only had good growth characteristics but also exhibited excellent probiotic properties indicating their potential as probiotics.

Isolation and Identification of Limosilactobacillus reuteri PSC102 and Evaluation of Its Potential Probiotic, Antioxidant, and Antibacterial Properties.

We isolated and characterized Limosilactobacillus reuteri PSC102 and evaluated its probiotic, antioxidant, and antibacterial properties. We preliminarily isolated 154 candidates from pig feces and analyzed their Gram nature, morphology, and lactic acid production ability. Based on the results, we selected eight isolates and tested their ability to produce digestive enzymes. Finally, we identified one isolate using 16S rRNA gene sequencing, namely, L. reuteri PSC102. We tested its probiotic properties in vitro, including extracellular enzyme activities, low pH and bile salt tolerance, autoaggregation and coaggregation abilities, adhesion to Caco-2 cells, antibiotic susceptibility, and hemolytic and gelatinase activities. Antioxidant activity was determined using 1-diphenyl-2-picrylhydrazyl and 2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical scavenging and reducing power assays. The antibacterial activity of this strain and its culture supernatant against enterotoxigenic Escherichia coli were evaluated using a time-kill assay and disk diffusion method, respectively. L. reuteri PSC102 exhibited tolerance toward low pH and bile salt and did not produce harmful enzymes or possess hemolytic and gelatinase activities. Its intact cells and cell-free extract exhibited potential antioxidant activities, and significantly inhibited the growth of enterotoxigenic E. coli. Our results demonstrate that L. reuteri PSC102 is a potential probiotic candidate for developing functional feed.

Biochemical and molecular regulatory mechanism of the pgpH gene on biofilm formation in Listeria monocytogenes.

PgpH gene has an important regulatory role on bacterial physiological activity, but studies on its regulation mechanism on biofilm formation of Listeria monocytogenes are lacking. Our aim was to investigate the effect of pgpH gene deletion on biofilm formation in L. monocytogenes. The ΔpgpH deletion strain of L. monocytogenes LMB 33 426 was constructed by homologous recombination. Deletion of the pgpH gene resulted in a significant reduction in biofilm formation. The swimming ability of the ΔpgpH strain on semisolid plates was unchanged compared to the wild-type strain (WT), and the auto-aggregation capacity of L. monocytogenes was decreased. RNA-seq showed that ΔpgpH resulted in the differential expression of 2357 genes compared to WT. pgpH inactivation resulted in the significant downregulation of the cell wall formation-related genes dltC, dltD, walK, and walR and the flagellar assembly related genes fliG and motB. This study shows that the deletion of pgpH gene regulates biofilm formation and auto-aggregation ability of L. monocytogenes by affecting the expression of flagellar assembly and cell wall related genes. pgpH has a global regulatory effect on biofilm formation in L.monocytogenes.