Lactobacillus Cells Research Articles

O-268 Re-considering the endometrial microbiome: a comparison of DNA- and RNA-based sequencing techniques within the same cohort

Abstract Study question Does the analysis of the endometrial microbiome provide the same information when using DNA or RNA sequencing-based techniques? Summary answer DNA vs. RNA-based microbiome analysis techniques demonstrate significant microbial compositional differences, meaning that the previous endometrial 16S rRNA gene-based microbiome analysis results might be overestimated. What is known already In recent years, high-throughput sequencing technologies have revolutionised the field of reproductive microbiome research. Our understanding of the composition of endometrial microbiome predominantly relies on DNA-based 16S rRNA gene profiling method. Regardless of its effectiveness and low cost, its underestimation of microbial diversity, abundance, or functionality and lack of detection precision on species level have been highlighted. The meta-transcriptome analysis, RNA-based method, overcomes these limitations and identifies functional genes that are actively expressed by the alive microbes. This study aims to elucidate for the first time the endometrial microbiome using a dual approach of 16S rRNA gene-method and meta-transcriptomic analyses. Study design, size, duration In total forty-seven women with infertility at ages 27-42 years old were enrolled in the present study. Paired endometrial samples, endometrial brushing and Pipelle biopsy were collected from each participant at the mid-secretory menstrual phase (LH + 7/9). Participants/materials, setting, methods Endometrial samples were collected using Tao Brush for 16S rRNA analysis (DNA analysis) and Pipelle endometrial curette for meta-transcriptomic analysis (total RNA analysis). QIAamp UCP Pathogen Mini Kit was used for DNA extraction and 16S rRNA gene V3-V4 regions were sequenced on MiSeq. RNA was extracted using miRNeasy Micro kit, with rRNA removal by RiboZero kit and Libraries were generated using Stranded Total RNA Prep. Taxonomy was assigned by using Kraken2 (v2.2.1), Bracken (v2.7). Main results and the role of chance To the best of our knowledge, this is the first study to compare endometrial microbial identification using both metagenomics (16S rRNA sequencing) and meta-transcriptomics (meta-RNA sequencing) within the same cohort. Analysis of the composition of the microorganisms by bacterial 16S rRNA gene sequencing revealed that the most abundant bacterial genus in the endometrium was Lactobacillus. In the meta-transcriptome analysis, no microorganisms belonging to the Lactobacillus genus were detected in high abundance. This indicates that the relative abundance of this genus at the DNA level does not necessarily imply microbial activity or the presence of viable Lactobacillus in the endometrium. The meta-transcriptomics analysis detected microbial taxa such as Staphylococcus, Bacillus, Streptococcus, and Burkholderia as the most dominant. The results suggest that DNA-based detection of microorganisms in the endometrium may be overestimated due to the presence of naked DNA sequences or microorganisms from the vagina and cervix. Furthermore, RNA-based analysis demonstrates a population of active microorganisms different from the image shown by DNA analysis. Altogether, our study results indicate that the uterine microenvironment, as previously identified through DNA sequencing, may partly reflect the vaginocervical microenvironment, with the uterine tissue being a low biomass site not dominated by lactobacilli. Limitations, reasons for caution The endometrial samples were paired; however, DNA was analysed in the endometrial brushing sample while RNA in the tissue biopsy, which might result in some differences in microbial composition. Wider implications of the findings Contrary to the general belief of the Lactobacillus dominance in the human endometrium, our study suggests that the endometrial microenvironment may be harbouring DNA fragments and/or cells of lactobacilli originating from the lower reproductive tract. Our study results call out to re-consider/re-analyse the endometrial microbiome in health and disease. Trial registration number not applicable

Effect of Postbiotics and Killed Cells of lactobacillus acidophilus Bacteria on Improving the Storage Properties of Soft Cheese

Effect of Postbiotics and Killed Cells of lactobacillus acidophilus Bacteria on Improving the Storage Properties of Soft Cheese

Formulation of Culture Medium for the Enumeration of Lactic Streptococci and Lactobacilli from Fermented Milk Products

Aims: The present study is focused to formulate a single selective differential medium for the enumeration of mixed lactic flora such as lactic streptococci and lactobacilli in domestic and market fermented milk products.
 Study Design: In order to enumerate lactic streptococci and lactobacilli in a mixed flora of fermented milk, formulation of single selective medium was optimized using inhibitors and indicator instead of separate selective medium for lactic streptococci and lactobacilli.
 Place and Duration of Study: The present study was conducted in the Department of dairy Microbiology, Dairy Science College, Karnataka Veterinary, Animal and Fisheries Sciences University (KVAFSU), Hebbal, Bengaluru-24, Karnataka from February 2020 to February 2021.
 Methodology: Fermented milk samples like curd, yoghurt were collected, serially diluted and pour plated using Readymade M17 and MRS agar media and formulated selective yeast glucose agar medium. Lactic colonies obtained were enumerated, expressed as log10cfu/g and critical difference was calculated to declare significance and non-significance among the microbial parameters.
 Results: Readymade M17 and MRS agar media gave better recovery of viable cells of lactic streptococci and lactobacilli from market samples of curd, yoghurt and domestic curd samples. The study helped to convert a general purpose medium yeast glucose agar as selective differential medium with addition of calcium propionate of 0.8 per cent to avoid Bacillus spore formers and sodium benzoate of 1.2 per cent to inhibit yeast, the common contaminants in fermented milk with 0.05 per cent BCP that led to formation of purple colonies of lactic streptococci and yellow colonies of lactobacilli.
 Conclusion: The selective yeast glucose agar with 0.8 per cent and sodium benzoate of 1.2 per cent with 0.05 per cent BCP with purple colonies of lactic streptococci and yellow colonies of lactobacilli can be successfully used. This study verified the enumeration of mixed lactic flora in fermented milk products instead of M17 medium for lactic streptococci and MRS for lactobacilli, separately.

The effect of oral synbiotics on the gut microbiota and inflammatory biomarkers in healthy adults: a systematic review and meta-analysis

Abstract Context Prior research has explored the effect of synbiotics, the combination of probiotics and prebiotics, on the gut microbiota in clinical populations. However, evidence related to the effect of synbiotics on the gut microbiota in healthy adults has not been reviewed to date. Objective A systematic review and meta-analysis was conducted to comprehensively investigate the effect of synbiotics on the gut microbiota and inflammatory markers in populations of healthy adults. Data Sources Scopus, PubMed, Web of Science, ScienceDirect, MEDLINE, CINAHL, and The Cochrane Library were systematically searched to retrieve randomized controlled trials examining the primary outcome of gut microbiota or intestinal permeability changes after synbiotic consumption in healthy adults. Secondary outcomes of interest were short-chain fatty acids, inflammatory biomarkers, and gut microbiota diversity. Data Extraction Weighted (WMD) or standardized mean difference (SMD) outcome data were pooled in restricted maximum likelihood models using random effects. Twenty-seven articles reporting on 26 studies met the eligibility criteria (n = 1319). Data Analysis Meta-analyses of 16 studies showed synbiotics resulted in a significant increase in Lactobacillus cell count (SMD, 0.74; 95% confidence interval [CI], 0.15, 1.33; P = 0.01) and propionate concentration (SMD, 0.22; 95% CI, 0.02, 0.43; P = 0.03) compared with controls. A trend for an increase in Bifidobacterium relative abundance (WMD, 0.97; 95% CI, 0.42, 2.52; P = 0.10) and cell count (SMD, 0.82; 95% CI, 0.13, 1.88; P = 0.06) was seen. No significant differences in α-diversity, acetate, butyrate, zonulin, IL-6, CRP, or endotoxins were observed. Conclusion This review demonstrates that synbiotics modulate the gut microbiota by increasing Lactobacillus and propionate across various healthy adult populations, and may result in increased Bifidobacterium. Significant variations in synbiotic type, dose, and duration should be considered as limitations when applying findings to clinical practice. Systematic Review Registration PROSPERO no. CRD42021284033.

Rapid and Accurate Quantification of Viable Lactobacillus Cells in Infant Formula by Flow Cytometry Combined with Propidium Monoazide and Signal-Enhanced Fluorescence In Situ Hybridization.

Lactobacillus is an important member of the probiotic bacterial family for regulating human intestinal microflora and preserving its normalcy, and it has been widely used in infant formula. An appropriate and feasible method to quantify viable Lactobacilli cells is urgently required to evaluate the quality of probiotic-fortified infant formula. This study presents a rapid and accurate method to count viable Lactobacilli cells in infant formula using flow cytometry (FCM). First, Lactobacillus cells were specifically and rapidly stained by oligonucleotide probes based on a signal-enhanced fluorescence in situ hybridization (SEFISH) technique. A DNA-binding fluorescent probe, propidium monoazide (PMA), was then used to accurately recognize viable Lactobacillus cells. The entire process of this newly developed PMA-SEFISH-FCM method was accomplished within 2.5 h, which included pretreatment, dual staining, and FCM analysis; thus, this method showed considerably shorter time-to-results than other rapid methods. This method also demonstrated a good linear correlation (R2 = 0.9994) with the traditional plate-based method with a bacterial recovery rate of 91.24%. To the best of our knowledge, the present study is the first report of FCM combined with PMA and FISH for the specific detection of viable bacterial cells.

Klebsiella as an α-tocopherol source facilitating Lactobacillus plantarum fermentation in rice straw silage1

Silage serves as the indispensable diet of ruminants, the increasing mechanism of α-tocopherol during silage making is unclear. Rice straw lacks chlorophyll after harvesting the grain, this can eliminate the impact of tocopherols formed by the breakdown of chlorophyll. Here, we explored the α-tocopherol source, its influencing factor, and its relationship with dominant lactic acid bacteria in rice straw silage treated without or with different additives (sodium benzoate, Lactobacillus plantarum, cell wall degrading enzymes, the combination of Lactobacillus plantarum and cell wall degrading enzymes) and vacuum times (5, 8, 11, and 14 s) after ensiling for 42 d. We found that the pathogenic Klebsiella was traced as the source of increased α-tocopherol in rice straw silage. The residue air in the silo, pH value, and additive variety had impacts on Klebsiella activity, which was strongly active at levels of residue air in the silo and pH that were high. As an acidic niche creator, Lactobacillus plantarum was more effective than sodium benzoate in restraining Klebsiella. Despite having a low acidity tolerance, Klebsiella was still present in rice straw silage treated with L. plantarum. The relationship between Klebsiella and L. plantarum was that Klebsiella could afford α-tocopherol to the multiplication of L. plantarum and residue capsular polysaccharide protected Klebsiella from escaping the extinction in rice straw silage.

Chemical Composition and Antimicrobial Activity of Lavender (Lavandula angustifolia Mill.), Peppermint (Mentha piperita L.), Raspberry Seed (Rubus idaeus L.), and Ylang-Ylang (Cananga odorata (Lam.) Essential Oils—Towards Hurdle Technologies in the Production of Chocolate Mousse

The growing consumer demand for the development of functional foods with a number of benefits for the consumer has led to a considerable increase in the studies focused on examining different natural agents to be included in the composition of newly developed functional foods. The chemical compositions of the essential oils (EOs) of lavender (Lavandula angustifolia Mill.), peppermint (Mentha piperita L.), raspberry seed (Rubus idaeus L.), and ylang-ylang (Cananga odorata (Lam.)) were determined using gas chromatography with a mass selective detector (GC-MS). The antibacterial and antifungal activities of these EOs were examined using a high-throughput 96-well microplate bioassay procedure and the MICs of each EO against each test microorganism were determined. The results indicated significant antimicrobial activity against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538, Salmonella abony NTCC 6017, Pseudomonas aeruginosa NBIMCC 1390, Bacillus subtilis ATCC 19659, Penicillium chrysogenum ATCC 28089, Fusarium moniliforme ATCC 38932, Aspergillus niger ATCC 1015, and Aspergillus flavus ATCC 9643. To explore their potential applications in food preservation, model chocolate mousse food emulsions were prepared that incorporated EOs and/or selected probiotic lactobacilli strains in both free and encapsulated forms. The inclusion of EOs and/or probiotic lactobacilli resulted in enhanced microbial safety and an extended shelf life. Furthermore, the chocolate mousse variants that were biopreserved with the inclusion of probiotic lactobacilli maintained a high viable lactobacillus cell concentration throughout the storage period. As a result, these products would not only be suitable as functional probiotic foods but also as effective delivery vehicles for probiotic lactobacilli.

Promising application of probiotic microorganisms as Pickering emulsions stabilizers

The purpose of this work was to study the ability of nineteen food-grade microorganisms as Pickering emulsion (PE) stabilizers. Medium-chain triacylglycerol (MCT) oil-in-water (50:50) PEs were fabricated by 10 wt% or 15 wt% of thermally-inactivated yeast, cocci, Bacillus spp. and lactobacilli cells. The characteristics of microorganisms related to “Pickering stabilization” including morphology, surface charge, interfacial tension, and “contact angle” were firstly studied. After that, the cells-stabilized PEs were characterized from both kinetic and thermodynamic viewpoints, microstructure and rheological properties. The interfacial tension and “contact angle” values of various microorganisms ranged from 16.33 to 38.31 mN/m, and from 15° to 106°, respectively. The mean droplet size of PEs ranged from 11.51 to 57.69 µm. Generally, the physical stability of cell-stabilized PEs followed this order: lactobacilli > Bacillus spp. > cocci > yeast. These variations were attributed to the morphology and cell wall composition. Increasing the microorganism concentration significantly increased the physical stability of PEs from a maximum of 12 days at 10 wt% to 35 days at 15 wt% as a result of better interface coverage. Shear-thinning and dominant elastic behaviors were observed in PEs. Physical stability was affected by the free energy of detachment. Therefore, food-grade microorganisms are suggested for stabilizing PEs.

Antibiofilm and antimicrobial activity of Lactobacillus cell free supernatant against Pseudomonas aeruginosa isolated from burn wounds.

The present study investigated the antimicrobial and anti-biofilm effects of indigenous Lactobacillus probiotic strains on Pseudomonas aeruginosa isolated from burn wound infection in laboratory conditions. The effect of 7 probiotic strains isolated from infant faeces on the pathogenicity factors of P. aeruginosa, including protease, elastase, antibiofilm and antipyocyanin was measured. Also, diffusion methods in the well and micro broth dilution were used to evaluate the antimicrobial activity of probiotics. All tests were performed in triplicate. A negative control and a positive control were used for each test. SPSS version 22 software was used for statistical analysis, and a p < 0.05 was considered statistically significant. A total of 30 clinical isolates of P. aeruginosa were isolated. The elastolytic activity of P. aeruginosa isolates decreased after adding Cell free supernatant (CFS) of each Lactobacillus. L1, L4, L5, and L6 strains had a 100% inhibitory effect on pathogen isolates. L3 and L7 strains had the lowest inhibitory effect. The inhibitory effect of CFS extracted from lactobacilli on protease production by P. aeruginosa. L1, L4, L5, and L6 strains had an inhibitory effect on all tested isolates. L2, L3, and L7 strains had a less inhibitory effect. L4 strain had the highest inhibitory effect on pyocyanin production by P. aeruginosa (50%), followed by L5 (43.3%), L1 (40%), and L6 (23.3%) strains. L3 and L7 strains had no inhibitory effect on the pyocyanin production of P. aeruginosa isolates. It was found that the CFS of 4 isolates (L1, L4, L5, and L6) was the most active extract and had a 100% inhibitory effect against biofilm formation of all P. aeruginosa strains. The L3 strain had the least inhibitory effect against the biofilm formation of pathogens. Overall, this study showed that probiotics could be promising alternatives to combat the pathogenicity of P. aeruginosa in burn wounds.

Monitoring the process of yogurt spoilage by dielectric measurements and spread plate method

In my research work, I primarily focused on the investigation of yogurt (made from home-made raw milk) spoilage by microbiological and dielectric measurements. During the experiment, I continuously monitored the changes in aerobic and anaerobic Lactobacillus cell counts of the product, as a possible spoilage process would cause the deteriorative microbes to displace the lactic acid bacteria, and I also monitored the changes in the dielectric properties of the sample material at 400 MHz frequency. The research results verified that there is a strong correlation between the variation in live cell counts and dielectric parameters in both aerobically and anaerobically cultured lactic acid bacteria. The main conclusions of the results are that the change in the bacterial count, and thus the deterioration process leading to it, can be indirectly monitored in the dairy product under study by low-frequency determination of both the dielectric constant and the loss factor.

Nanomechanical changes in probiotic bacteria under antibiotics exposure: Implications on Lactobacillus biofilm formation

Recognition of the microbial cell's surface constituents' biophysical properties is an important research topic, allowing a better understanding of the cell's behaviour under different conditions. Atomic force microscopy (AFM) was employed in this study to analyse the basis of the nanomechanical changes in probiotic bacteria under nitrofurantoin, furazolidone, and nitrofurazone exposure. Recorded significant changes in the two Lactobacillus strains cells morphology, topography, and adhesion parameters resulted in the increase of the cells' longitude (up to 2.58 μm), profile height (by around 0.50 μm), and decrease in the adhesion force (up to 13.58 nN). Young's modulus and adhesion energy decreased within 96 h, however with no negative effect on the cells' morphology or loss of structural integrity. Observed modifications present the mode of action of the 5-nitrofuran derivative antibiotics on probiotic biofilm formation and suggest activation of the multilevel adaptation mechanisms to counteract unfavorable environments. A visual change in bacterial morphology such as an increased surface-to-volume ratio might be a link between molecular-level events and outcomes in individual cells and biofilms. This paper for the first time shows, that these antibiotics affect the properties of non-target microorganisms as lactobacilli, and might impair biofilm formation. However, the degree of such transformations depends on the delivered active substance.

Biological control of foodborne pathogens by lactic acid bacteria: A focus on juice processing industries

The use of lactic acid bacteria (LAB) in foods as biocontrol agents against foodborne pathogens has become increasingly known. Under the premise that controlling the adhesion of microorganisms to food contact surfaces is an essential step for meeting the goals of food processing, the aim of this work was to investigate the inhibitory and anti-biofilm effectiveness of Lactobacillus rhamnosus GG (ATCC 53103) and Lactobacillus casei (ATCC 393) against Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes. Lactobacillus strains (108CFU/ml) and pathogens (104CFU/ml) were evaluated to monitor LAB anti-adhesive and antibiofilm effect, in two main scenarios: (i) co-adhesion and (ii) pathogen incorporation to stainless steel surfaces with a protective biofilm of Lactobacillus cells. In (i) the predominant effect was observed in L. rhamnosus against S. enterica and L. monocytogenes, whereas in (ii) both LAB significantly reduced the number of pathogenic adherent cells. The effect of pre-established LAB biofilms was more successful in displacing the three pathogens than when they were evaluated under co-adhesion. These findings show that both LAB can be considered good candidates to prevent or inhibit the adhesion and colonization of L. monocytogenes, S. enterica and E. coli O157:H7 on surfaces and conditions of relevance for juice processing industries, offering alternatives for improving the safety and quality of fruit-based products.

Effect of Flaxseed Mucilage on the Probiotic, Antioxidant, and Structural-Mechanical Properties of the Different Lactobacillus Cells

A positive effect of flaxseed mucilage (FSM) addition (at concentrations of 0.1, 0.2, and 0.4%) to MRS and milk whey nutrient medium on the survival, auto-aggregation, hydrophobicity, adhesive, and antioxidant properties of L. bulgaricus, L. fermentum AG8, and L. plantarum AG9 was shown. It was found that the AG 8 strain became less sensitive to 7% NaCl concentrations (the cell survival rate in the experiment with 0.4% flaxseed mucilage increased by 10% compared to the control). Cultivation in the presence of FSM led to an increase in auto-aggregation, especially in the case of AG8 (from 60 to 85%) and AG9 (from 50 to 80%) strains, and an increase in hydrophobicity was seen: for L. fermentum AG8, it was from 30% to 62–72%, for L. fermentum AG9 from 30% to 35–42%, and for L. bulgaricus from 20% to 30%. The adhesive properties of the L. fermentum AG8 and L. plantarum AG9 cells increased from 0.472 to 1 nN (nanonewton) and from 0.630 to 2.5 nN, respectively. The presence of flaxseed mucilage increased the total phenolic content in cell-free supernatants after 48 h of cultivation. The concentration of 0.1–0.2% FSM increased the OH-scavenging activity of milk whey nutrient medium cell-free supernatants of strains AG8 and AG9 by 7–10%. Flaxseed mucilage can serve as a promising bioactive additive that elevates antioxidant activity, increases the resistance and survival of Lactobacillus cells in the gastrointestinal tract, and leads to the synthesis of lipase and α-glucosidase inhibitors. The co-culture of these lactic acid bacteria in the presence of FSM and milk components in the form of whey leads to the synthesis of lipase and α-glucosidase inhibitors more than the culturing on de Man, Rogosa, and Sharpe broth.

Apple-derived 3D scaffold for improving gastrointestinal viability and in-situ growth of probiotics

This study develops a novel low-cost microbial delivery system by transforming common food materials such as apple tissue into a 3D scaffold. Apple tissue scaffold was constructed by decellularization of intact tissue using a minimal amount of sodium dodecyl sulfate (0.5 % w/v). Vacuum-assisted infusion of model probiotic Lactobacillus cells led to a high encapsulation yield of probiotic cells (1010 CFU/g of scaffold) in 3D scaffolds on a wet basis. The bio-polymer coated 3D scaffolds with infused cells significantly enhanced the survivability of infused probiotic cells during simulated gastric and intestinal digestions. In addition, imaging and plate counting results validate the growth of the infused cells in the 3D scaffold after 1–2 days of fermentation in MRS media, while cells without infusion in the scaffold had limited attachment with the intact apple tissue. Overall, these results highlight the potential of the apple tissue-derived 3D scaffold to deliver probiotic cells and include the biochemical compositions to support the growth of delivered microbial cells in the colon.

Synergistic Inhibitory Effect of Lactobacillus Cell Lysates and Butyrate on Poly I:C-Induced IL-8 Production in Human Intestinal Epithelial Cells.

Postbiotics include cell lysates (CLs), enzymes, cell wall fragments, and heat-killed bacteria derived from probiotics. Although postbiotics are increasingly being considered for their potential health-promoting properties, the effects of postbiotics on virus-mediated inflammatory responses in the intestine have not been elucidated. Hence, the present study aimed to examine whether CLs of Lactipantibacillus plantarum (LP CL) and Lacticaseibacillus rhamnosus GG (LR CL) could inhibit virus-mediated inflammatory responses in the human intestinal epithelial cell line HT-29 in vitro. Pretreatment with LP CL and LR CL significantly inhibited interleukin (IL)-8 production, which was induced by poly I:C, a synthetic analog of double-stranded RNA (dsRNA) viruses, at the mRNA and protein levels in HT-29 cells. However, peptidoglycans and heat-killed L. plantarum and L. rhamnosus GG did not effectively inhibit IL-8 production. LP CL and LR CL attenuated the poly I:C-induced phosphorylation of ERK and JNK and the activation of NF-κB, suggesting that these CLs could inhibit poly I:C-induced IL-8 production by regulating intracellular signaling pathways in HT-29 cells. Furthermore, among the short-chain fatty acids, butyrate enhanced the inhibitory effect of CLs on poly I:C-induced IL-8 production at the mRNA and protein levels in HT-29 cells, while acetate and propionate did not. Taken together, these results suggest that both LP CL and LR CL could act as potent effector molecules that can inhibit virus-mediated inflammatory responses and confer synergistic inhibitory effects with butyrate in human intestinal epithelial cells.

Adsorption abilities and mechanisms of Lactobacillus on various nanoplastics

As a new type of pollutants, nanoplastics (NPs), which are easily ingested by humans from food wraps, salt, drinking water, have been widely detected in various water environments, and are a threat to human health. It is therefore urgent to develop an efficient method to remove NPs from the diet or relief its harm. In the present study, the possibility of a well-known human probiotic, lactic acid bacteria (LAB), was evaluated to remove NPs from food as an absorbent. The results indicated that LAB from infant feces could efficiently absorb three types NPs, i.e. polypropylene (PP), polyethylene (PE), and polyvinyl chloride (PVC) with the adsorption rates of PP > PE > PVC (PP 78.57%, PE 71.59%, PVC 66.57%) and the Nile red-stained NPs being aggregated on the surfaces of Lactobacillus cells. The smaller the particle size, the stronger the ability of NP adsorption on the cell surface. The hydrophobicity of NPs and bacterial cells affected the adsorption process. The measurement of adsorption rates of different cell components indicated that the overall adsorption effect of cell was better than that of individual cell component. The results of molecular dynamics analysis revealed that adsorption was mainly caused by electrostatic interactions, van der Waals forces, and hydrogen bonds. The hydrophobic interaction was also involved in adsorption process. Overall, this research may provide new information for developing new strategies for NPs removal in intestinal environment.

Optimization and adsorption characteristics of beads based on heat-inactivated bacterial biomaterial towards the pesticide Cypermethrin.

Beads containing heat-inactivated bacterial biomaterial (BBBs) were prepared for removal of cypermethrin (CPM) and the conditions for this removal were evaluated and optimized via single-factor coupled orthogonal experiments based on five factors. The adsorption characteristics of BBBs and the binding mechanism were then explored. Results showed that the adsorption rate of CPM could reach 98% with beads prepared under optimized conditions: equal volumes of Lactobacillus cell debris derived from 1×1011 CFU; 2% hydroxypropyl-β-cyclodextrin and 2.5% activated carbon concentration, were mixed to give mixture TM, and this and SA, was mixed 1:4 with sodium alginate (SA) and beads were prepared using a 26-Gauge needle). The best adsorption conditions were initial CPM concentration of 10 mg l-1, incubation time of 24 h, and rotational speed of 180 rpm. BBBs have a well-formed structure and abundant surface functional groups, such as -COOH, -OH, -NH, -CH, -CO, -C=C. The adsorption process conformed to pseudo-second-order kinetic, and it was also a Freundlich monolayer adsorption, and the calculated maximum adsorption capacity was 9.69 mg g-1 under optimized conditions. BBBs showed the highest CPM removal capacity and a good tolerance ability. Our results provided a theoretical foundation for developing an adsorbent with heat-inactivated Lactobacillus plantarum (L. plantarum) RS60 for removing CPM in wastewater or drinks.

Production and characterization of nondairy gluten-free fermented beverage based on buckwheat and lentil.

The present study aimed to optimize the formulation of buckwheat/lentil gluten-free beverages fermented with Lactobacillus plantarum and Bifidobacterium bifidum. Physicochemical parameters of 14 different beverages, such as pH, acidity, total solids, ash, total phenol content, antioxidant activity, and sensory test, were assessed after 24 h of fermentation. The results showed that the numbers of viable cells of lactobacilli and bifidobacteria on the first day of the experiment were 9.9 and 9.6 log (CFU ml-1), respectively, which were over 9 log (CFU ml-1). During 24 h from the fermentation, the number of viable cells for all beverages decreased, which reached an average probiotic count of 8.81 log (CFU ml-1) that was statistically significantly different from the probiotic count before fermentation (p < .05). Cell viability was evaluated and shelf life was estimated during 15-day refrigerated storage. At the end of the storage (15th day), the beverages contained an average of 8.4 log (CFU ml-1) of live lactobacilli cells and 7.8 log (CFU ml-1) of viable bifidobacterial cells. The optimized levels of independent factors for sprouted buckwheat and lentil flours were 51.96% and 48.04%, respectively. The optimized probiotic beverage was contained 0.25 (% lactic acid) acidity, 5.7 pH, 7.9% total solids, 0.4% ash, 41.02% DPPH, 26.96 (mg GAE/ml) phenol compounds, and 8.65 log (CFU ml-1) probiotic count. The optimized beverage had distinct organoleptic properties on day 15 of refrigerated storage. This study showed that Bifidobacterium bifidum can be used for the development of potentially probiotic beverage with sprouted buckwheat and lentil.

Wall teichoic acid-dependent phagocytosis of intact cell walls of Lactiplantibacillus plantarum elicits IL-12 secretion from macrophages.

Selected lactic acid bacteria can stimulate macrophages and dendritic cells to secrete IL-12, which plays a key role in activating innate and cellular immunity. In this study, we investigated the roles of cell wall teichoic acids (WTAs) displayed on whole intact cell walls (ICWs) of Lactiplantibacillus plantarum in activation of mouse macrophages. ICWs were prepared from whole bacterial cells of several lactobacilli without physical disruption, and thus retaining the overall shapes of the bacteria. WTA-displaying ICWs of several L. plantarum strains, but not WTA-lacking ICWs of strains of other lactobacilli, elicited IL-12 secretion from mouse bone marrow-derived macrophages (BMMs) and mouse macrophage-like J774.1 cells. The ability of the ICWs of L. plantarum to induce IL-12 secretion was abolished by selective chemical elimination of WTAs from ICWs, but was preserved by selective removal of cell wall glycopolymers other than WTAs. BMMs prepared from TLR2- or TLR4-deficient mouse could secret IL-12 upon stimulation with ICWs of L. plantarum and a MyD88 dimerization inhibitor did not affect ICW-mediated IL-12 secretion. WTA-displaying ICWs, but not WTA-lacking ICWs, were ingested in the cells within 30 min. Treatment with inhibitors of actin polymerization abolished IL-12 secretion in response to ICW stimulation and diminished ingestion of ICWs. When overall shapes of ICWs of L. plantarum were physically disrupted, the disrupted ICWs (DCWs) failed to induce IL-12 secretion. However, DCWs and soluble WTAs inhibited ICW-mediated IL-12 secretion from macrophages. Taken together, these results show that WTA-displaying ICWs of L. plantarum can elicit IL-12 production from macrophages via actin-dependent phagocytosis but TLR2 signaling axis independent pathway. WTAs displayed on ICWs are key molecules in the elicitation of IL-12 secretion, and the sizes and shapes of the ICWs have an impact on actin remodeling and subsequent IL-12 production.

Lactobacillus cell envelope-coated nanoparticles for antibiotic delivery against cariogenic biofilm and dental caries

BackgroundDue to their prevalence, dental caries ranks first among all diseases endangering human health. Therefore, the prevention of caries is of great significance, as caries have become a serious public health problem worldwide. Currently, using nanoscale drug delivery systems to prevent caries has received increased attention. However, the preventive efficacy of these systems is substantially limited due to the unique physiological structure of cariogenic biofilms. Thus, novel strategies aimed at combating cariogenic biofilms to improve preventive efficiency against caries are meaningful and very necessary. Herein, inspired by cell membrane coating technology and Lactobacillus strains, we coated triclosan (TCS)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (TCS@PLGA-NPs) with an envelope of Lactobacillus (LA/TCS@PLGA-NPs) and investigated their potential as a nanoparticle delivery system against cariogenic biofilms and dental caries.ResultsLA/TCS@PLGA-NPs were successfully prepared with favorable properties, including a coated envelope, controllable size, negative charge, sustained drug-release kinetics and so on. The LA/TCS@PLGA-NPs inherited native properties from the source cell surface, thus the LA/TCS@PLGA-NPs adhered to S. mutans, integrated into the S. mutans biofilm, and interfered with the biofilm formation of S. mutans. The nanoparticles significantly inhibited the activity, biomass and virulence gene expression of S. mutans biofilms in vitro. Additionally, LA/TCS@PLGA-NPs exhibited a long-lasting inhibitory effect on the progression of caries in vivo. The safety performance of the nanoparticles is also favorable.ConclusionsOur findings reveal that the antibiofilm effect of LA/TCS@PLGA-NPs relies not only on the inheritance of native properties from the Lactobacillus cell surface but also on the inhibitory effect on the activity, biomass and virulence of S. mutans biofilms. Thus, these nanoparticles could be considered feasible candidates for a new class of effective drug delivery systems for the prevention of caries. Furthermore, this work provides new insights into cell membrane coating technology and presents a novel strategy to combat bacterial biofilms and associated infections.Graphical