The Discovery, Molecular Cloning, and Characterization of Dextransucrase LmDexA and Its Active Truncated Mutant from Leuconostoc mesenteroides NN710.

Dextransucrases play a crucial role in the production of dextran from economical sucrose; therefore, there is a pressing demand to explore novel dextransucrases with better performance. This study characterized a dextransucrase enzyme, LmDexA, which was identified from the Leuconostoc mesenteroides NN710. This bacterium was isolated from the soil of growing dragon fruit in Guangxi province, China. We successfully constructed six different N-terminal truncated variants through sequential analysis. Additionally, a truncated variant, ΔN190LmDexA, was constructed by removing the 190 amino acids fragment from the N-terminal. This truncated variant was then successfully expressed heterologously in Escherichia coli and purified. The purified ΔN190LmDexA demonstrated optimal hydrolysis activity at a pH of 5.6 and a temperature of 30 °C. Its maximum specific activity was measured to be 126.13 U/mg, with a Km of 13.7 mM. Results demonstrated a significant improvement in the heterologous expression level and total enzyme activity of ΔN190LmDexA. ΔN190LmDexA exhibited both hydrolytic and transsaccharolytic enzymatic activities. When sucrose was used as the substrate, it primarily produced high-molecular-weight dextran (>400 kDa). However, upon the addition of maltose as a receptor, it resulted in the production of a significant amount of oligosaccharides. Our results can provide valuable information for enhancing the characteristics of recombinant dextransucrase and potentially converting sucrose into high-value-added dextran and oligosaccharides.

Modulation of gene expression in immune-related organs by in ovo stimulation with probiotics and prophybiotics in broiler chickens.

In ovo stimulation has been studied intensively as an alternative to antibiotic use in poultry production. We investigated the potential use of a probiotic in combination with a phytobiotic as a prophybiotic for in ovo stimulation and reported its beneficial effects on the gut microbiome of broiler chickens. The current study further investigates the gene expression in the immune-related organs of these chickens to understand the tissue-specific immunomodulatory effects of the treatments. The selected prophybiotic (Leuconostoc mesenteroides with garlic aqueous extract) and its probiotic component alone were injected into ROSS308 chicken eggs on the 12th day of incubation, and gene expression in cecal tonsils, spleen, and liver at 35 days of age was determined using qPCR method. The relative expression of each treatment was compared to the positive control, chickens injected with physiological saline in ovo. The results displayed a downregulation of pro- and anti-inflammatory cytokines in the cecal tonsils of the probiotic group and the liver of the prophybiotic group. The spleen displayed upregulated AVBD1 in both groups and upregulated IL1-ß in the probiotic group. The probiotic group displayed increased expression of genes related to metabolism of energy (COX16), protein (mTOR), and lipids (CYP46A1) whereas the prophybiotic group displayed reduced expression of genes related to cholesterol synthesis (SREBP1) and glucose transportation (SLC2A2) in the liver. In conclusion, Leuconostoc mesenteroides differentially modulated gene expression in chickens when administered in ovo in combination with garlic aqueous extract. Further in ovo studies with different prophybiotic combinations are required to optimize the benefits in broiler chickens.

Leuconostoc gelidum Is the Major Species Responsible for the Spoilage of Cooked Sausage Packaged in a Modified Atmosphere, and Hop Extract Is the Best Inhibitor Tested.

Cooked sausages packaged in a modified atmosphere (MAP: 20% CO2, 70% N2, <0.2% O2) with evident yellow stains were analyzed. The aims of this work were to study the microbial cause of the spoilage and to evaluate different antimicrobial compounds to prevent it. Leuconostoc gelidum was identified as the primary cause of the yellow coating in spoiled cooked sausage, as confirmed by its intentional inoculation on slices of unspoiled sausage. Leuconostoc gelidum was the main bacteria responsible for the yellow coating in spoiled cooked sausage, as confirmed by its intentional inoculation on slices of unspoiled sausage. The yellow color was also evident during growth in the model system containing cooked sausage extract, but the colonies on MRS agar appeared white, demonstrating that the food substrate stimulated the production of the yellow pigment. The spoilage was also characterized by different volatile compounds, including ketones, ethanol, acetic acid, and ethyl acetate, found in the spoiled cooked sausage packages. These compounds explained the activity of Leuc. gelidum because they are typical of heterofermentative LAB, cultivated either on food substrates or in artificial broths. Leuc. gelidum also produced slight swelling in the spoiled packages. The efficacy of different antimicrobials was assessed in model systems composed of cooked sausage extract with the antimicrobials added at food product concentrations. The data showed that sodium lactate, sodium acetate, and a combination of sodium lactate and sodium diacetate could only slow the growth of the spoiler-they could not stop it from occurring. Conversely, hop extract inhibited Leuc. gelidum, showing a minimal inhibitory concentration (MIC) of approximately 0.008 mg CAE/mL in synthetic broth and 4 mg CAE/kg in cooked sausage slices. Adding hop extract at the MIC did not allow Leuc. gelidum growth and did not change the sensorial characteristics of the cooked sausages. To our knowledge, this is the first report of the antimicrobial activities of hop extracts against Leuc. gelidum either in vitro or in vivo.

Draft genome sequences of 53 Lactococcus and Leuconostoc strains isolated from two undefined DL-starter cultures.

This study presents the complete genomes of 53 strains of Lactococcus and Leuconostoc isolated from two undefined DL-starter cultures originating from Denmark, Tistrup, and P. The genomes were reconstructed using long-read, nanopore-based DNA sequencing, delivering comprehensive data set for comparative genomics and taxonomic classification, with potential utility in dairy fermentation processes.

Upregulation of Immune checkpoint PD-L1 in Colon cancer cell lines and activation of T cells by Leuconostoc mesenteroides.

Globally colorectal cancer ranks as the third most widespread disease and the third leading cause of cancer-associated mortality. Immunotherapy treatments like PD-L1 blockade have been used to inhibit the PD-L1 legend, which boosts the activity of cytotoxic T lymphocytes. Recently, studies suggest that some probiotics could potentially enhance the effectiveness of immunotherapy treatments for cancer patients. We found that in Caco-2 and HT-29 cells, the live Leuconostoc mesenteroides treatment resulted an increase in the PD-L1 expression and this treatment stimulated interferon-gamma (IFN-γ) production in Jurkat T-cells. Due to the well-established ability of IFN-γ to enhance PD-L1 expression, the combination of IFN-γ and L. mesenteroides was used in colon cancer cell lines and a resulting remarkable increase of over tenfold in PD-L1 expression was obtained. Interestingly, when L. mesenteroides and IFN-γ are present, the blockage of PD-L1 using PD-L1 antibodies not only improved the viability of Jurkat T-cells but also significantly boosted the levels of IFN-γ and IL-2, the T-cells activation marker cytokines. In addition to upregulating PD-L1, L. mesenteroides also activated Toll-like receptors (TLRs) and NOD-like receptors (NODs) pathways, specifically through TLR2 and NOD2, while also exerting a suppressive effect on autophagy in colon cancer cell lines. In conclusion, our findings demonstrate a significant upregulation of PD-L1 expression in colon cancer cells upon co-culturing with L. mesenteroides. Moreover, the presence of PD-L1 antibodies during co-culturing activates Jurkat T cells. The observed enhancement in PD-L1 expression may be attributed to the inhibition of the Autophagy pathway or activation of the hippo pathway. KEY POINTS: Co-culturing L. mesenteroides increases PD-L1 gene and protein transaction in colon cancer. L. mesenteroides existing enhances T cells viability and activity. GPCR41/42 is a possible link between L. mesenteroides, YAP-1 and PD-L1.

The novel bacteriocin BacYB1 produced by Leuconostoc mesenteroides YB1: From recent analytical characterization to biocontrol Verticillium dahliae and Agrobacterium tumefaciens.

Biocontrol of phytopathogens involving the use of bioactive compounds produced by lactic acid bacteria (LAB), is a promising approach to manage many diseases in agriculture. In this study, a lactic acid bacterium designated YB1 was isolated from fermented olives and selected for its antagonistic activity against Verticillium dahliae (V. dahliae) and Agrobacterium tumefaciens (A. tumefaciens). Based on the 16S rRNA gene nucleotide sequence analysis (1565 pb, accession number: OR714267), the new isolate YB1 bacterium was assigned as Leuconostoc mesenteroides YB1 (OR714267) strain. This bacterium produces an active peptide "bacteriocin" called BacYB1, which was purified in four steps. Matrix-assisted lasers desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) based approach was performed to identify and characterize BacYB1. The exact mass was 5470.75 Da, and the analysis of the N-terminal sequence (VTRASGASTPPGTASPFKTL) of BacYB1 revealed no significant similarity to currently available antimicrobial peptides. The BacYB1 displayed a bactericidal mode of action against A. tumefaciens. The potentiel role of BacYB1 to supress the growth of A. tumefaciens was confirmed by live-dead cells viability assay. In pot experiments, the biocontrol efficacy of BacYB1 against V. dahliae wilt on young olive trees was studied. The percentage of dead plants (PDP) and the final mean symptomes severity (FMS) of plants articifialy infected by V. dahliae and treated with the pre-purified peptide BacYB1 (preventive and curative treatments) were significantly inferior to untreated plants. Biochemical analysis of leaves of the plants has shown that polyophenols contents were highly detected in plants infected by V. dahliae and the highest contents of chlorophyl a, b and total chlorophyll were recorded in plants treated with the combination of BacYB1 with the biofertilisant Humivital. BacYB1 presents a promising alternative for the control of Verticillium wilt and crown gall diseases.

Exploration of Exopolysaccharide from Leuconostoc mesenteroides HDE-8: Unveiling Structure, Bioactivity, and Food Industry Applications.

A strain of Leuconostoc mesenteroides HDE-8 was isolated from homemade longan fermentation broth. The exopolysaccharide (EPS) yield of the strain was 25.1 g/L. The EPS was isolated and purified, and the structure was characterized using various techniques, including X-ray diffraction (XRD), nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, high-performance size exclusion chromatography (HPSEC), and scanning electron microscopy (SEM). The monosaccharide composition of the EPS was glucose, with a molecular weight (Mw) of 1.7 × 106 Da. NMR spectroscopy revealed that the composition of the HDE-8 EPS consisted of D-glucose pyranose linked by α-(1→4) and α-(1→6) bonds. The SEM analysis of the EPS showed an irregular sheet-like structure. Physicochemical analysis demonstrated that EPSs exhibit excellent thermal stability and high viscosity, making them suitable for fermentation in heat-processed and acidic foods. Additionally, milk coagulation tests showed that the presence of EPSs promotes milk coagulation when supplemented with sucrose. It suggests that EPSs have wide-ranging potential applications as food additives, improving the texture and taste of dairy products. This study provides practical guidance for the commercial use of HDE-8 EPSs in the food and related industries.

Draft genome sequence of Leuconostoc falkenbergense isolated from naturally fermented buffalo milk curd.

This study reports the draft genome of Leuconostoc falkenbergense strain BSMRAU-M1L5, isolated from artisanal buffalo milk curd in Bangladesh. The draft genome spans 1,776,471 bp, with 50× coverage and 96 contigs.

Effects of water-soluble and water-insoluble α-glucans produced in situ by Leuconostoc citreum SH12 on physicochemical properties of fermented soymilk and their structural analysis.

This study investigated the effect of in situ produced water-soluble α-glucan (LcWSG) and water-insoluble α-glucan (LcWIG) from Leuconostoc citreum SH12 on the physicochemical properties of fermented soymilk. α-Glucans produced by Leuc. citreum SH12 improved water-holding capacity, viscosity, viscoelasticity and texture of fermented soymilk. Gtf1365 and Gtf836 of the five putative glucansucrases were responsible for synthesizing LcWSG and LcWIG during soymilk fermentation, respectively. Co-fermentation of soymilk with Gtf1365 and Gtf836 and non-exopolysaccharide-producing Lactiplantibacillus plantarum D1031 indicated that LcWSG effectively hindered the whey separation of fermented soymilk by increasing viscosity, while LcWIG improved hardness, springiness and accelerated protein coagulation. Fermented soymilk gel formation was mainly based on hydrogen bonding and hydrophobic interactions, which were promoted by both LcWSG and LcWIG. LcWIG has a greater effect on α-helix to ß-sheet translation in fermented soymilk, causing more rapid protein aggregation and thicker cross-linked gel network. Structure-based exploration of LcWSG and LcWIG from Leuc. citreum SH12 revealed their distinct roles in the physicochemical properties of fermented soymilk due to their different ratio of α-1,6 and α-1,3 glucosidic linkages and various side chain length. This study may guide the application of the water-soluble and water-insoluble α-glucans in fermented plant protein foods for their quality improvement.

Cell density and extracellular matrix composition mitigate bacterial biofilm sensitivity to UV-C LED irradiation.

Ultraviolet-C light-emitting diodes (UV-C LEDs) are an emerging technology for decontamination applications in different sectors. In this study, the inactivation of bacterial biofilms was investigated by applying an UV-C LED emitting at 280 nm and by measuring both the influence of the initial cell density (load) and presence of an extracellular matrix (biofilm). Two bacterial strains exposing diverging matrix structures and biochemical compositions were used: Pseudomonas aeruginosa and Leuconostoc citreum. UV-C LED irradiation was applied at three UV doses (171 to 684 mJ/cm2) on both surface-spread cells and on 24-h biofilms and under controlled cell loads, and bacterial survival was determined. All surface-spread bacteria, between 105 and 109 CFU/cm2, and biofilms at 108 CFU/cm2 showed that bacterial response to irradiation was dose-dependent. The treatment efficacy decreased significantly for L. citreum surface-spread cells when the initial cell load was high, while no load effect was observed for P. aeruginosa. Inactivation was also reduced when bacteria were grown under a biofilm form, especially for P. aeruginosa: a protective effect could be attributed to abundant extracellular DNA and proteins in the matrix of P. aeruginosa biofilms, as revealed by Confocal Laser Scanning Microscopy observations. This study showed that initial cell load and exopolymeric substances are major factors influencing UV-C LED antibiofilm treatment efficacy. KEY POINTS: • Bacterial cell load (CFU/cm2) could impact UV-C LED irradiation efficiency • Characteristics of the biofilm matrix have a paramount importance on inactivation • The dose to be applied can be predicted based on biofilm properties.

Monitoring the Season-Prevalence Relationship of Vairimorpha ceranae in Honey Bees (Apis mellifera) over One Year and the Primary Assessment of Probiotic Treatment in Taichung, Taiwan.

Microsporidiosis, which is caused by the pathogen Vairimorpha ceranae, is a prevalent disease in the honey bee (Apis mellifera) and might lead to significant adult honey bee mortality. In this study, we conducted an annual survey of the mature spore load of V. ceranae in the guts of nurse bees and forager bees in the apiary of National Chung Hsing University (NCHU) in Taiwan. The results indicated that, on average, honey bees hosted approximately 2.13 × 106 mature spore counts (MSCs)/bee in their guts throughout the entire year. The highest number of MSCs was 6.28 × 106 MSCs/bee, which occurred in April 2020, and the lowest number of MSCs was 5.08 × 105 MSCs/bee, which occurred in November 2020. Furthermore, the guts of forager bees had significantly higher (>58%) MSCs than those of nurse bees. To evaluate the potential of the probiotic to treat microsporidiosis, the lactic acid bacterium Leuconostoc mesenteroides TBE-8 was applied to honey bee colonies. A significant reduction (>53%) in MSCs following probiotic treatment was observed, indicating the potential of probiotic treatment for managing microsporidiosis. This research provided information on V. ceranae MSCs in the honey bee gut at NCHU in Taiwan and the MSCs' correlation with the annual season. Furthermore, a potential probiotic treatment for microsporidiosis was assessed for future management.

Synergistic effects of combined probiotics Bacillus pumilis D5 and Leuconostoc mesenteroide B4 on immune enhancement and disease resistance in Litopenaeus vannamei.

This study investigated the effects of two distinct probiotics, Leuconostoc mesenteroides B4 (B4) and Bacillus pumilus D5 (D5), along with their combination, on the diet of white shrimp (Litopenaeus vannamei) during an eight-week feeding trial. The diets tested included B4 + dextran at 107 CFU/g feed (the B4 group), D5 alone at 107 CFU/g feed (the D5 group), and a combination of B4 + dextran and D5 at 5 × 106 CFU/g feed each (the B4+dextran + D5 group). Relative to the control group, those administered probiotics exhibited moderate enhancements in growth. By the eighth week, the weight gain for the B4, D5, and B4+D5 groups was 696.50 ± 78.15%, 718.53 ± 130.73%, and 693.05 ± 93.79%, respectively, outperforming the control group's 691.66 ± 31.10% gain. The feed conversion ratio was most efficient in the B4 group (2.16 ± 0.06), closely followed by B4+D5 (2.21 ± 0.03) and D5 (2.22 ± 0.06), with the control group having the highest ratio (2.27 ± 0.03). While phenoloxidase activity was somewhat elevated in the B4 and D5 groups, no significant differences were noted in respiratory burst activity or total hemocyte count across all groups. Challenge tests at weeks 4 and 8 showed that the B4 + D5 combination offered superior protection against AHPND-causing Vibrio parahaemolyticus. The 4-week cumulative survival rate was highest in shrimp treated with B4 + dextran + D5 (56.25%), followed by B4 + dextran (31.25%), control (18.75%), and lowest in D5 (12.5%). By week 8, the B4 + dextran + D5 (43.75%) and B4 + dextran (37.5%) groups significantly outperformed the control group (6.25%, p < 0.05), with no significant difference observed between the D5 group (37.5%) and the control group at day 56. Analysis of the shrimp's foregut microbiota revealed an increase in unique OTUs in the B4 and B4 + D5 groups. Compared to the control, Proteobacteria abundance was reduced in all probiotic groups. Potential pathogens like Vibrio, Bacteroides, Neisseria, Botrytis, Clostridioides, and Deltaentomopoxvirus were detected in the control but were reduced or absent in probiotic groups. Beneficial microbes such as Methanobrevibacter and Dictyostelium in the B4+D5 group, and Sugiyamaella in the B4 group, showed significant increases. Probiotics also led to higher transcript levels of nitric oxide synthase in the hemocytes, and lysozyme and transglutaminase in the midgut, along with lysozyme and α2-macroglobulin in the foregut. Notably, the combined B4 + D5 probiotics synergistically enhanced the expression of superoxide dismutase and prophenoloxidase in the foregut, indicating an improved immune response. In summary, this study demonstrates that the probiotics evaluated, especially when used in combination, significantly boost the expression of specific immune-related genes, enhance the bacterial diversity and richness of the intestine, and thus prevent the colonization and proliferation of Vibrio spp. in L. vannamei.

Bacteremia due to Leuconostoc species: A 13-year single-center case series / Bacteriemia por Leuconostoc spp: serie de casos en un hospital de tercer nivel a lo largo de 13 años

Introduction: Leuconostoc spp. are facultatively anaerobic Gram-positive cocci involved in cases of hospital-acquired bacteremia, mainly in immunocompromised hosts. The available data is scarce due to its uncommon presentation. Methods: We describe all the episodes of Leuconostoc spp. bacteremia in a third level hospital in a 13-year period (2008–2021). Results: Four cases of clinically relevant bacteremia were detected. All cases were categorized as catheter-related. The following risk factors were found: previous glycopeptide therapy (75%), use of parenteral nutrition (100%) and cancer (75%). All isolates showed susceptibility to beta-lactams. Catheter removal was performed and wide spectrum antimicrobials were administered, with clinical response in all cases except one. Discussion: Apart from cancer and glycopeptide exposure, disruption of skin barrier and gastrointestinal conditions were identified as risk factors, as it was concordantly underlined in other case series. Susceptibility to beta-lactams is usually maintained. Catheter removal and administration of an active antibacterial therapy seem to be the best approach for Leuconostoc spp. catheter-related bacteremia.(AU)

Introducción: Los microorganismos del género Leuconostoc son cocos grampositivos anaerobios facultativos, involucrados en casos de bacteriemia en pacientes hospitalizados, especialmente con factores de inmunosupresión. La literatura disponible es escasa por su baja frecuencia. Métodos: Describimos todos los episodios de bacteriemia por Leuconostoc spp. en un hospital de tercer nivel en un periodo de 13 años (2008-2021). Resultados: Se detectaron 4 aislamientos clínicamente significativos. Todos ellos fueron categorizados como bacteriemia relacionada con catéter. Se identificaron como factores de riesgo: la exposición previa a glucopéptidos (75%), nutrición parenteral (100%) y cáncer (75%). Todos los aislamientos presentaron sensibilidad a betalactámicos. Se procedió a retirada del catéter y se administraron antimicrobianos de amplio espectro con buena respuesta clínica, salvo en un caso. Discusión: Además del cáncer y la exposición a glucopéptidos, la disrupción de la barrera cutánea y las enfermedades gastrointestinales se identificaron como factores de riesgo, al igual que en otras series. La sensibilidad a betalactámicos suele mantenerse. La retirada del catéter y el uso de terapia antibiótica activa parece ser la mejor alternativa terapéutica para la bacteriemia relacionada con catéter por Leuconostoc spp.(AU)

The exopolysaccharides produced by Leuconostoc mesenteroides XR1 and its effect on silk drawing phenomenon of yoghurt.

Yoghurt fermented by Leuconostoc mesenteroides XR1 from Kefir grains was found to produce a unique silk drawing phenomenon. This property was found to be associated with the exopolysaccharides (EPS), X-EPS, produced by strain XR1. In order to better understand the mechanism that produced this phenomenon, the X-EPS was extracted, purified and characterized. The molecular weight and monosaccharide composition were determined by size exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS) and ion chromatography (IC) analysis, respectively. The results showed that its molecular weight was 4.183 × 106 g/mol and its monosaccharide composition was glucose, and glucuronic acid, with the contents of 567.6148 and 0.2096 µg/mg, respectively. FT-IR and NMR analyses showed that X-EPS was an α-pyranose polysaccharide and was composed of 92.22 % α-(1 â†’ 6) linked d-glucopyranose units and 7.77 % α-(1 â†’ 3) branching. Furthermore, it showed a chain-like microstructure with branches in atomic force microscopy (AFM) and scanning electron microscopy (SEM) experiments. These results suggested that the unique structure of X-EPS, gave the yoghurt a strong viscosity and cohesiveness, which resulted in the silk drawing phenomenon. This work suggested that X-EPS holds the potential for food and industrial applications.

Complete genome sequences of two Leuconostoc carnosum strains: 4010 and AMS1.

Leuconostoc carnosum is a bacterial species commonly associated with meat spoilage. However, some strains exhibit preservative effects due to bacteriocin production. Here, we report the complete genome sequences for two strains, L. carnosum 4010 and AMS1. Bacteriocin-related gene clusters were found on the plasmids of both strains.

Genomic insights into antibiotic resistance genes in Leuconostoc citreum strains isolated from artisanal buffalo milk curd in Bangladesh through whole-genome sequencing.

We sequenced the genome of Leuconostoc citreum strains BSMRAU-M1L6 and BSMRAU-M1L13 isolated from artisanal buffalo milk curd in Bangladesh. The draft genomes of BSMRAU-M1L6 and BSMRAU-M1L13 are 1,869,891 and 1,890,611 bp, respectively, with 50.0× coverage (both) and 65 and 75 contigs, respectively.

Damage of polyethylene microplastics on the intestine multilayer barrier, blood cell immune function and the repair effect of Leuconostoc mesenteroides DH in the large-scale loach (Paramisgurnus dabryanus).

Polyethylene microplastics (PE-MPs) has become a global concern due to their widespread distribution and hazardous properties in aquatic habitats. In this study, the accumulation effect of PE-MPs in the intestine of large-scale loach (Paramisgurnus dabryanus) was explored by adding different concentrations of PE-MPs to the water, the destination of PE-MPs after breaking the intestinal barrier and the effects caused. The collected data showed that PE-MPs accumulation for 21d altered the histomorphology and antioxidant enzyme activity of the intestine, induced dysbiosis of the intestinal flora. 10 mg/L of PE-MPs induced a significant increase in the transcript levels of intestinal immunity factors in loach after 21d of exposure. Moreover, the levels of diamine oxidase (DAO) and d-lactic acid (D-Lac) in the gut and serum of loach were significantly increased after exposure to PE-MPs at all concentrations (1, 5, 10 mg/L). Subsequently, the presence of PE-MPs was detected in the blood, suggesting that the disruption of the intestinal multilayer barrier allowed PE-MPs to spill into the circulation. The accumulation of PE-MPs (1,5,10 mg/L) in the blood led to massive apoptosis and necrosis of blood cells and activated phagocytosis in response to PE-MPs invasion. To alleviate the damage, this study further exposure the effect of probiotics on PE-MPs treated loach by adding Leuconostoc mesenteroides DH (109 CFU/g) to the feed. The results showed that DH significantly increased the intestinal index and reduced the levels of DAO and D-Lac. To investigate the reason, we followed the PE-MPs in the intestine and blood of the loach and found that the number of PE-MPs particles was significantly reduced in the probiotic group, while the PE-MPs content in the feces was elevated. Thus, we concluded that DH reducing the accumulation of PE-MPs in the intestinal by increases fecal PE-MPs, which in turn mitigates the damage to the intestinal barrier caused by PE-MPs, and reduces the amount of PE-MPs in the blood. This work offers a robust analysis to understand the mechanisms of damage to the intestinal barrier by MPs and the fate of MPs after escaping the intestinal barrier and provide a new perspective on the application of probiotics in mitigating PE-MPs toxicity.

Growth Control of Listeria monocytogenes in Raw Sausage via Bacteriocin-Producing Leuconostoc carnosum DH25.

The current study addresses the critical issue of Listeria monocytogenes growth in raw sausage/meat products leading to human infections, most commonly listeriosis, which is known for its high fatality rate. This research focuses on the isolation, identification, and screening of lactic acid bacteria from various meat and fish products in Switzerland. In total, 274 lactic acid bacteria strains were isolated from 30 different products and were screened for their ability to inhibit Listeria monocytogenes growth, with 51 isolates demonstrating anti-Listeria activity at 8 °C, 15 °C, 25 °C, and 37 °C. Further experiments, using a meat model and a raw sausage challenge test, demonstrated that Leuconostoc carnosum DH25 significantly inhibited Listeria monocytogenes growth during the ripening and storage of the tested meat/sausage. This inhibitory effect was found to be attributed to the bacteriocins produced by Leuconostoc carnosum DH25 rather than factors like pH or water activity. The stability of the anti-Listeria substances was examined, revealing their resistance to temperature and pH changes, making Leuconostoc carnosum DH25 a promising protective culture for raw sausages. The genome sequencing of this strain confirms its safety, with no antibiotic resistance genes or virulence factors detected, and reveals the presence of the structural genes for the production of the bacteriocin LeucocinB-Ta11a. This study underscores the potential of LAB strains and their bacteriocins as effective tools for enhancing food safety and preventing Listeria monocytogenes growth in meat products, offering valuable insights into biocontrol strategies in the food industry.

The community of lactic acid bacteria during kimoto-style seed mash making process and its control.

Kimoto-style seed mash making processes such as the kimoto and yamahai-moto processes are driven by various microorganisms, and it is very important to make lactic acid bacteria grow stably for the brewing of a sake product with consistent quality. A model of bacterial transition from spherical lactic acid bacteria to rod-shaped lactic acid bacteria during kimoto-making has been advocated, but the model cannot explain all cases of a transition of a bacterial community during kimoto-making at various breweries. Several studies have described unique bacterial transition patterns that differ from those considered in the proposed model, and it is possible that factors such as differences in the initial bacterial community among breweries may cause the diversity of bacterial transitions. In this minireview, I summarize the research concerning the community of lactic acid bacteria during the kimoto-style seed mash making process, and I discuss how stable lactic acid fermentation can be achieved.

Optimization of asymmetric bioreduction conditions of 1-indanone by Leuconostoc mesenteroides N6 using a face-centered design-based multi-objective optimization model.

There has been an increasing interest in biocatalysts over the past few decades in order to obtain high efficiency, high yield, and environmentally benign procedures aiming at the manufacture of pharmacologically relevant chemicals. Lactic Acid Bacteria (LAB), a microbial group, can be employed as biocatalysts while performing asymmetric reduction of prochiral ketones. In this study, Leuconostoc mesenteroides N6 was used for the asymmetric bioreduction 1-indanone. And then, a novel and innovative face-centered design-based multi-objective optimization model was used to optimize experimental conditions. Also, the experimental design factors were defined as agitation speed, incubation period, pH, and temperature for optimization to acquire the maximum enantiomeric excess (ee) and conversion rate (cr) values. When using the face-centered design-based multi-objective optimization model, the optimum culture conditions corresponded to 96.34 and 99.42%, ee and cr responses, respectively, were pH = 5.87, incubation temperature = 35 °C, incubation period = 50.88 h, and agitation speed = 152.60 rpm. Notably, the validation experiment under the optimum model conditions confirmed the model results. This study demonstrated the importance of the optimization and the efficiency of the face-centered design-based multi-objective model.