Search Results (9)

The stabilization of essential oils in emulsions using surfactants of natural origin is of significant interest, and the use of biosurfactants produced by lactic acid bacteria could be an alternative. In this study, the total and partial substitution of Tween 80 in cinnamon bark essential oil emulsions was proposed using a glycolipopeptide biosurfactant produced by Lactiplantibacillus plantarum Tw226. The oil-in-water emulsions formulated contained cinnamon bark oil at a concentration of 5 g/L, with Tween 80, the biosurfactant, or a mixture of both as the surfactant agent, reaching a final concentration of 5 g/L. Homogenization was performed using a high-speed homogenizer. The emulsion with both the biosurfactant and Tween 80 was classified as a nanoemulsion (Z-av < 200 nm) that was stable for eight weeks, while the one with only the biosurfactant was a mini-emulsion (200 > Z-av < 500 nm). Furthermore, the emulsion with a combination of surfactants exhibited antioxidant activity equal to that of the emulsion with only Tween 80 and higher than that of the emulsion with only the biosurfactant. The antifungal activities of the three emulsions against Candida tropicalis, Candida krusei, and Zygosaccharomyces bailii did not change, regardless of the surfactant used, according to MIC values. In conclusion, a mixture of biosurfactant and Tween 80 or biosurfactant alone is an alternative for reducing or substituting synthetic surfactants in essential cinnamon bark oil emulsions, depending on their desired physical and functional properties. This work amplifies the scarce knowledge of essential oil emulsions stabilized with biosurfactants produced by lactic acid bacteria. Full article

Lactic acid bacteria (LAB) fermentation has been claimed as an effective way of modifying the sensory properties of plant-based foods. However, not much has been published on the influence of different LAB strains on the flavour of the volatile organic compounds (VOCs) produced. Using a defined medium (DM) and proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS), we assessed the VOCs produced by seven LAB strains, Levilactobacillus brevis WLP672 (LB672), Lactobacillus delbrueckii WLP677 (LD677), Pediococcus damnosus WLP661 (PD661), Lactiplantibacillus plantarum LP100 (LP100), Pediococcus pentosaceus PP100 (PP100), Pediococcus damnosus 5733 (PD5733), and Lentilactobacillus buchneri 5335 (LU5335), at three time points during fermentation (0, 7, and 14 days) at either 25 or 35 °C. Significant variations in VOC production were observed among LAB strains, growing in the same DM composition at either 25 °C or 35 °C. Specifically, the concentration of m/z 87.043 (t.i. diacetyl) was significantly (p < 0.05) higher at 7 days of fermentation at 35 °C by LP100, followed by PP100 at 35 °C and PD661 at 25 °C compared to the other strains at either 25 or 35 °C. The concentration of m/z 115.112 (t.i. 2-heptanone) was significantly (p < 0.05) higher at 7 days of fermentation at either 25 or 35 °C by LP100 compared to the other strains at all temperature and time points. The concentration of m/z 49.011 (t.i. methanethiol) was significantly (p < 0.05) higher after 7 days of fermentation at 35 °C by LB672 compared to the other strains at either 25 or 35 °C. The concentration of m/z 71.085 (t.i. 3-methyl butanol) was significantly (p < 0.05) higher after 7 days of fermentation at either 25 or 35 °C by PD661, LU5335, or PD5733 compared to the other strains studied. A notable increase in specific VOC concentrations was observed at 35 °C compared to 25 °C. This research demonstrates that LAB strains generate distinct VOC profiles in a DM based on strains and fermentation conditions. Therefore, this knowledge provides a basis for controlling and enhancing flavour in plant-based fermentations. Full article

In order to explore the effects of additives on the chemical composition, fermentation characteristics, and bacterial community of Pennisetum giganteum z.x.lin silage, Pennisetum giganteum z.x.lin was ensiled with no additives (CON), cellulase (CE), Lactiplantibacillus plantarum (LP), or the combination of cellulase and Lactiplantibacillus plantarum (LPCE) at room temperature for 60 days, respectively. The results indicated that LPCE had the highest dry matter (DM) content. Compared with CON, LP exhibited higher (p < 0.05) levels of water-soluble carbohydrate (WSC), crude protein (CP), and lactic acid (LA), along with a higher (p < 0.05) ratio of LA/acetic acid (AA). Meanwhile, silage inoculated with cellulase (CE and LPCE) showed lower (p < 0.05) contents of acid detergent fiber (ADF) and neutral detergent fiber (NDF) than CON. Furthermore, additive treatments improved the bacterial community composition of silage, and Lactobacillus was abundant in LPCE (LDA score > 4.0). Compared with CE and LP, LPCE more effectively promoted the transformation of microbial functions, resulting in an upregulated (p < 0.05) carbohydrate metabolism and a downregulated (p < 0.05) membrane transport. In conclusion, cellulase or Lactiplantibacillus plantarum improved the silage quality of Pennisetum giganteum z.x.lin by reducing the fiber content or enhancing LA fermentation, and their combination exhibited a powerful ability to establish a bacterial community dominated by Lactobacillus, which facilitated the production of high-quality silage. Full article

Currently, there is increasing interest in the commercial utilization of probiotics isolated from traditional fermented food products. Therefore, this study aimed to investigate the probiotic potential of Lactiplantibacillus plantarum (L. plantarum) Z22 isolated from naturally fermented mustard. The results suggest that L. plantarum Z22 exhibits good adhesion ability, antibacterial activity, safety, and tolerance to acidic conditions and bile salts. We further determined the anti-inflammatory mechanism and properties of L. plantarum Z22 and found that L. plantarum Z22 could significantly reduce the secretion of pro-inflammatory cytokines, including interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and the expression of the pro-inflammatory mediator cyclooxygenase-2 (COX-2) protein in LPS-induced RAW 264.7 cells. In addition, L. plantarum Z22 also effectively inhibited the signaling pathways of nuclear factor κB (NF-κB) and mitogen-activated protein kinases (MAPKs). This effect can be attributed to a decrease in the levels of reactive oxygen species (ROS) and increased heme oxygenase-1 (HO-1) expression. Moreover, whole-genome sequencing revealed that L. plantarum Z22 contains gene-encoding proteins with anti-inflammatory functions, such as beta-glucosidase (BGL) and pyruvate kinase (PK), as well as antioxidant functions, including thioredoxin reductase (TrxR), tyrosine-protein phosphatase, and ATP-dependent intracellular proteases ClpP. In summary, these results indicated that L. plantarum Z22 can serve as a potential candidate probiotic for use in fermented foods such as yogurt (starter cultures), providing a promising strategy for the development of functional foods to prevent chronic diseases. Full article

Lactic acid bacteria (LAB) are the most common probiotics, and they present excellent inhibitory effects on pathogenic bacteria. This study aimed to explore the anti-biofilm potential of the purified active substance of Lactiplantibacillus plantarum, named Z102-E. The effects of Z102-E on Listeria monocytogenes were investigated in detail, and a transcriptomic analysis was conducted to reveal the anti-biofilm mechanism. The results indicated that the sub-MIC of Z102-E (3.2, 1.6, and 0.8 mg/mL) decreased the bacterial growth and effectively reduced the self-aggregation, surface hydrophobicity, sugar utilization, motility, biofilm formation, AI-2 signal molecule, contents of extracellular polysaccharides, and extracellular protein of L. monocytogenes. Moreover, the inverted fluorescence microscopy observation confirmed the anti-biofilm effect of Z102-E. The transcriptomic analysis indicated that 117 genes were up-regulated and 214 were down-regulated. Z102-E regulated the expressions of genes related to L. monocytogenes quorum sensing, biofilm formation, etc. These findings suggested that Z102-E has great application potential as a natural bacteriostatic agent. Full article

Lactic acid bacteria (LAB) fermentation is a viable approach for producing plant-based flavour compounds; however, little is understood about the impact of different LAB strains and medium compositions on the production of volatile organic compounds (VOCs). This study investigated the impact of the addition of individual amino acids (AAs) (L-leucine, L-isoleucine, L-phenylalanine, L-glutamic acid, L-aspartic acid, L-threonine, or L-methionine) to a defined medium (DM) on the generation of VOCs (after 0, 7, and 14 days) by one of three LAB strains (Levilactobacillus brevis WLP672 (LB672), Lactiplantibacillus plantarum LP100 (LP100), and Pediococcus pentosaceus PP100 (PP100)), using proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS). The concentration of m/z 45.031 (t.i. acetaldehyde) was significantly (p < 0.05) higher after 7 days of fermentation by LP100 in the DM supplemented with threonine compared to all other media fermented by all three strains. The concentrations of m/z 49.012 (t.i. methanethiol) and m/z 95.000 (t.i. dimethyl disulfide) were significantly (p < 0.05) higher after 7 days of fermentation by either LP100, PP100, or LB672 in the DM supplemented with methionine compared to all other media. Information on the role of individual AAs on VOCs generation by different LAB strains will help to guide flavour development from the fermentation of plant-based substrates. Full article

Probiotics are known for their positive effects on the gut microbiota. There is growing evidence that the infant gut and skin colonization have a role in the development of the immune system, which may be helpful in the prevention and treatment of atopic dermatitis. This systematic review focused on evaluating the effect of single-strain probiotic lactobacilli consumption on treating children’s atopic dermatitis. Seventeen randomized placebo-controlled trials with the primary outcome of the Scoring Atopic Dermatitis (SCORAD) index were included in the systematic review. Clinical trials using single-strain lactobacilli were included. The search was conducted until October 2022 using PubMed, ScienceDirect, Web of Science, Cochrane library and manual searches. The Joanna Briggs Institute appraisal tool was used to assess the quality of the included studies. Meta-analyses and sub meta-analyses were performed using Cochrane Collaboration methodology. Due to different methods of reporting the SCORAD index, only 14 clinical trials with 1124 children were included in the meta-analysis (574 in the single-strain probiotic lactobacilli group and 550 in the placebo group) and showed that single-strain probiotic lactobacilli statistically significantly reduced the SCORAD index compared to the placebo in children with atopic dermatitis (mean difference [MD]: −4.50; 95% confidence interval [CI]: −7.50 to −1.49; Z = 2.93; p = 0.003; heterogeneity I² = 90%). The subgroup meta-analysis showed that strains of Limosilactobacillus fermentum were significantly more effective than strains of Lactiplantibacillus plantarum, Lacticaseibacillus paracasei or Lacticaseibacillus rhamnosus. A longer treatment time and younger treatment age statistically significantly reduced symptoms of atopic dermatitis. The result of this systematic review and meta-analysis shows that certain single-strain probiotic lactobacilli are more successful than others in reducing atopic dermatitis severity in children. Therefore, careful consideration to strain selection, treatment time and the age of the treated patients are important factors in enhancing the effectiveness of reducing atopic dermatitis in children when choosing probiotic single-strain lactobacilli. Full article

Galotyri is the most popular traditional Greek PDO soft acid-curd cheese. This study compared the microbial numbers and types and characterized the lactic acid bacteria (LAB) biota of two artisan-type Galotyri PDO cheese varieties, one marketed fresh (Brand-K) and the other ripened (Brand-Z). Two retail batches of each cheese variety were analyzed, and a total of 102 LAB isolates were biochemically identified. LAB (7.2–9.3 log CFU/g) prevailed in all cheeses, followed by yeasts (5.8–6.8 log CFU/g). Typical starter strains of Streptococcus thermophilus and Lactobacillus delbrueckii were the most abundant species in all batches. However, the fresh Brand-K cheeses had 1–3 log units higher thermophilic starter LAB counts than the ripened Brand-Z cheeses, which contained a more diverse viable LAB biota comprising Lacticaseibacillus paracasei, Leuconostoc mesenteroides, Lentilactobacillus (L. diolivorans, L. kefiri, L. hilgardii), Pediococcus inopinatus/parvulus, few spontaneous nonstarter thermophilic streptococci and lactobacilli, and Enterococcus faecium and E. faecalis at higher subdominant levels.Conversely, the fresh Brand-K cheeses were enriched in members of the Lactiplantibacillus plantarum group; other LAB species were sporadically isolated, including Lactococcus lactis. All retail cheeses were safe (pH 3.9–4.0). No Salmonella spp. or Listeria monocytogenes were detected in 25-g samples by culture enrichment; however, Listeria innocua and coagulase-positive staphylococci (850 CFU/g) survived in one ripened batch. Gram-negative bacteria were <100 CFU/g in all cheeses. In conclusion, ripening reduced the starter LAB viability but increased the nonstarter LAB species diversity in the present Galotyri PDO market cheeses. Full article

Vibrio parahaemolyticus is a widespread foodborne pathogen that causes serious seafood-borne gastrointestinal infections. Biofilm and quorum sensing (QS) are critical in regulating these infections. In this study, first, the ability of Lactiplantibacillus plantarum Z057 to compete, exclude, and displace V. parahaemolyticus biofilm was evaluated. Then, the inhibitory effects of L. plantarum Z057 extract (Z057-E) on V. parahaemolyticus biofilm and QS were explored from the aspects of biofilm biomass, metabolic activity, physicochemical properties, extracellular polymer matrix content, QS signal AI-2 activity, biofilm microstructure, and the expression levels of biofilm and QS-related genes. Results showed that L. plantarum Z057 effectively inhibited biofilm formation of V. parahaemolyticus and interfered with the adhesion of V. parahaemolyticus on the carrier surface. In addition, the Z057-E could significantly reduce the biofilm biomass, metabolic activity, hydrophobicity, auto-aggregation ability, swimming and swarming migration diameter, AI-2 activity, extracellular polysaccharide (EPS), and extracellular protein content of V. parahaemolyticus. Fluorescence microscope and scanning electron microscope (SEM) images demonstrated that the Z057-E could efficiently inactivate the living cells, destroy the dense and complete biofilm architectures, and reduce the essential component of the extracellular polymer matrix. Real-time fluorescence quantitative PCR revealed that the Z057-E treatment down-regulated the expression of flagellum synthesis-related genes (flaA, flgM), EPS, and extracellular protein synthesis-related genes (cpsA, cpsQ, cpsR, ompW), QS-related genes (luxS, aphA, opaR), and hemolysin secretion-related genes (toxS, toxR) of V. parahaemolyticus. Thus, our results suggested that L. plantarum Z057 could represent an alternative biocontrol strategy against foodborne pathogens with anti-adhesive, antibiofilm, and antiquorum sensing activities. Full article