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A large number of recalcitrant bacterial pathogens cannot be easily treated by antibiotics due to the existence of biofilm. Hence, an alternative strategy needs to be adopted to remove the biofilm without the development of antibiotic resistance. Bacteriocins, ribosome-mediated bacterial proteinaceous toxins, are found to have the potential to inhibit the growth of bacteria. In the present study, leucocin, extracted and purified from previously isolated bacteriocin-producing strain Leuconostoc lactis, showed a marked reduction (around 80%) in the growth of planktonic cells of Gram-negative Escherichia coli ATCC 25,922 compared to Nisin, a reference bacteriocin, and tetracycline, a conventional antibiotic. The considerable inhibition of the biofilm forming sessile cells with no significant cell revival even after removal of the treatment was also perceived. The scanning electron micrographs showed the considerable antibiofilm activities of the bacteriocin against the test organism. The bacteriocin treatment-mediated changes in the functional groups of the biofilm matrices are clearly visible from FTIR analysis. The confocal microscopic images showed the affinity of the bacteriocin towards the genetic material of the test organism and the reduction of the biofilm forming cells, which confirms the higher competence of the present leucocin as an antibiofilm agent in order to replace the conventional antibiotic. [ABSTRACT FROM AUTHOR]

Saccharomyces cerevisiae LBTF 21.3, Pichia manshurica LBTF 21.1, and Leuconostoc lactis LBTF 21.1 were used as single and mixed cultures in coffee fermentations. Fermentations carried out in glass jars with P. manshurica LBTF 21.1/Leuc. lactis LBTF 21.1 showed higher fermentation rates than S. cerevisiae LBTF 21.3/P. manshurica LBTF 21.1 or S. cerevisiae LBTF 21.3/Leuc. lactis LBTF 21.1. The highest cup quality was reached with P. manshurica LBTF 21.1/Leuc. lactis LBTF 21.1 (83.0 points). Full factorial design (22) carried out with P. manshurica LBTF 21.1 revealed that the higher proportion of water added before the fermentation resulted in higher production of acetic acid. A contrary effect of this variable was observed on the production of lactic acid with Leuc. lactis LBTF 21.1. Fermentations conducted in bioreactor evidenced the production of acetaldehyde by P. manshurica LBTF 21.1/Leuc. lactis LBTF 21.1, P. manshurica LBTF 21.1, and Leuc. lactis LBTF 21.1. Additionally, the highest cup quality was reached in fermentations with P. manshurica LBTF 21.1 (82.5 points) followed by Leuc. lactis LBTF 21.1 (81.5 points) and P. manshurica LBTF 21.1/Leuc. lactis LBTF 21.1 (81.0 points). Fermentations of coffee with single and mixed cultures are interesting strategies for the improvement of the sensory quality. [ABSTRACT FROM AUTHOR]

Synbiotics contain health-beneficial bacteria, i.e., probiotics and prebiotics selectively utilized by the probiotics. Herein, three probiotic strains, Leuconostoc lactis CCK940, L. lactis SBC001, and Weissella cibaria YRK005, and the oligosaccharides produced by these strains (CCK, SBC, and YRK, respectively) were used to prepare nine synbiotic combinations. Macrophages (RAW 264.7) were treated with these synbiotic combinations and the corresponding lactic acid bacteria and oligosaccharides alone to evaluate the treatments' immunostimulatory activities. The level of nitric oxide (NO) production was significantly higher in the macrophages treated with the synbiotics than in those treated with the corresponding probiotic strains and the oligosaccharide alone. The immunostimulatory activities of the synbiotics increased regardless of the probiotic strain and the type of oligosaccharide used. The expressions of tissue necrosis factor-α, interleukin-1β, cyclooxygenase-2, inducible NO synthase genes, and extracellular-signal-regulated and c-Jun N-terminal kinases were significantly higher in the macrophages treated with the three synbiotics than in those treated with the corresponding strains or with the oligosaccharides alone. These results indicate that the synergistic immunostimulatory activities of probiotics and the prebiotics they produced in the studied synbiotic preparations resulted from the activation of the mitogen-activated protein-kinase-signaling pathway. This study suggests the combined use of these probiotics and prebiotics in the development of synbiotic preparations as health supplements. [ABSTRACT FROM AUTHOR]

The patient, who was born spontaneously to a 22-year-old mother as G1P1Y1 with a weight of 2605 g at 37 weeks of gestation, had an Activity, Pulse, Grimace, Appearance and Respiration (APGAR) of 8 and 5, respectively, at the first and fifth minutes APGAR 9. Physical examination revealed that the patient’s general condition was moderate: body temperature was 36.7 °C, respiratory rate was 68 beats per minute, heart rate was 146 beats per minute, blood pressure was 59/33 mmHg, saturation was 92%, both hemithoraxes participated equally in respiration, consciousness was clear, and the sucking reflex was weak. Because the mother had a history of premature membrane rupture for 22 hours, ampicillin and gentamicin were given intravenously after a blood culture. Leuconostoc lactis was grown in a blood culture sent by the patient. On the 12th day of her hospitalization, the patient was discharged with full oral feeding, had started to weigh regularly, and had good general condition, oral intake, and activity. Leuconostoc species should be kept in mind in vancomycin-resistant gram-positive infections. It should be kept in mind that Leuconostoc lactis may be a cause of Early-onset neonatal sepsis, albeit very rarely.

Among various health functional foods, probiotics constitute the largest market. The interest in probiotics is increasing continuously according to the research results that gut health can control the immune function of the body, prevent diseases, and assist in treatment. In this study, dairy products and dressing sauces were developed using Ficus carica vinegar (FV), and their effects on colon cells were analyzed. When 5% FV was added to regular milk, the satisfaction with the resulting yogurt and ricotta cheese was high. The dairy product was Leuconostoc lactis, and the number of bacteria was more than 1.0×107∼1.0×108 CFU/mL. The product satisfied the health food standards as probiotics. An examination of the cell viability of Caco-2 cells, which proliferate similarly to human intestinal epithelial cells, revealed an approximately 19% increase in the proliferation rate when treated with whey at 10%. An antioxidant activity of up to 58% was recorded when the cells were treated with whey at various concentrations. In addition, excellent adhesion was observed for L.latis isolated from whey. This study confirmed that dairy products made using traditionally fermented FV assist intestinal health effectively as the microbiome.

Abstract Background Leuconostoc lactis forms a crucial member of the genus Leuconostoc and has been widely used in the fermentation industry to convert raw material into acidified and flavored products in dairy and plant-based food systems. Since the ecological niches that strains of Ln. lactis being isolated from were truly diverse such as the human gut, dairy, and plant environments, comparative genome analysis studies are needed to better understand the strain differences from a metabolic adaptation point of view across diverse sources of origin. We compared eight Ln. lactis strains of 1.2.28, aa_0143, BIOML-A1, CBA3625, LN19, LN24, WIKIM21, and WiKim40 using bioinformatics to elucidate genomic level characteristics of each strain for better utilization of this species in a broad range of applications in food industry. Results Phylogenomic analysis of twenty-nine Ln. lactis strains resulted in nine clades. Whole-genome sequence analysis was performed on eight Ln. lactis strains representing human gastrointestinal tract and fermented foods microbiomes. The findings of the present study are based on comparative genome analysis against the reference Ln. lactis CBA3625 genome. Overall, a ~ 41% of all CDS were conserved between all strains. When the coding sequences were assigned to a function, mobile genetic elements, mainly insertion sequences were carried by all eight strains. All strains except LN24 and WiKim40 harbor at least one intact putative prophage region, and two of the strains contained CRISPR-Cas system. All strains encoded Lactococcin 972 bacteriocin biosynthesis gene clusters except for CBA3625. Conclusions The findings in the present study put forth new perspectives on genomics of Ln. lactis via complete genome sequence based comparative analysis and further determination of genomic characteristics. The outcomes of this work could potentially pave the way for developing elements for future strain engineering applications.

Leuconostoc is mostly found in food, plants, and dairy products. Due to their innate genomic features, such as the presence of carbohydrate-active enzymes, bacteriocins, and plasmids, Leuconostoc spp. have great biotechnological potential. In this study, four strains were isolated and identified as Leuconostoc mesenteroides SG315 (LA), L. citreum SG255 (LB), L. lactis CCK940 (LC), and L. lactis SBC001 (LD). Comparative analysis was performed using their draft genome sequences. Differences among the four strains were analyzed using the average nucleotide identity, dot plot, and multiple alignments of conserved genomic sequences. Functional profiling revealed 2134, 1917, 1751, and 1816 open reading frames; 2023, 1823, 1655, and 1699 protein-coding genes; 60, 57, 83, and 82 RNA-coding genes; and GC content of 37.5 %, 38.8 %, 43.3 %, and 43.2 %, in LA, LB, LC, and LD, respectively. The total number of genes encoding carbohydrate-active enzymes was 76 (LA), 73 (LB), 57 (LC), and 67 (LD). These results indicate that the four strains shared a large number of genes, but their gene content is different. Furthermore, most genes with unknown functions were observed in the prophage regions of the genome. This study also elucidated the oligosaccharide utilization and folate biosynthesis pathways in Leuconostoc spp. Taken together, our findings provide useful information on the genomic diversity of CAZymes in the four Leuconostoc strains and suggest that these species could be used for potent exploitation.

Background: Leuconostoc lactis forms a crucial member of the genus Leuconostoc and has been widely used in the fermentation industry to convert raw material into acidified and flavored products in dairy and plant-based food systems. Since the ecological niches that strains of Ln. lactis being isolated from were truly diverse such as the human gut, dairy, and plant environments, comparative genome analysis studies are needed to better understand the strain differences from a metabolic adaptation point of view across diverse sources of origin. We compared eight Ln. lactis strains of 1.2.28, aa_0143, BIOML-A1, CBA3625, LN19, LN24, WIKIM21, and WiKim40 using bioinformatics to elucidate genomic level characteristics of each strain for better utilization of this species in a broad range of applications in food industry. Results: Phylogenomic analysis of twenty-nine Ln. lactis strains resulted in nine clades. Whole-genome sequence analysis was performed on eight Ln. lactis strains representing human gastrointestinal tract and fermented foods microbiomes. The findings of the present study are based on comparative genome analysis against the reference Ln. lactis CBA3625 genome. Overall, a ~ 41% of all CDS were conserved between all strains. When the coding sequences were assigned to a function, mobile genetic elements, mainly insertion sequences were carried by all eight strains. All strains except LN24 and WiKim40 harbor at least one intact putative prophage region, and two of the strains contained CRISPR-Cas system. All strains encoded Lactococcin 972 bacteriocin biosynthesis gene clusters except for CBA3625. Conclusions: The findings in the present study put forth new perspectives on genomics of Ln. lactis via complete genome sequence based comparative analysis and further determination of genomic characteristics. The outcomes of this work could potentially pave the way for developing elements for future strain engineering applications. [ABSTRACT FROM AUTHOR]

Miki, a traditional fermented rice beverage from Amami Oshima, Japan, is produced by spontaneous fermentation of porridge after saccharification using amylase of raw mashed sweet potatoes. Considering the health benefits of endogenous lactic acid bacteria (LAB) and the lack of comprehensive information on Miki, the microbiota characteristics and diversity of Miki were examined. In total, 15 products from four factories in Amami Oshima and one product each from two other regions were subjected to both culture-dependent and 16S rDNA (V4) amplicon sequencing analyses. The total, LAB, and yeast viable counts were 6.9–9.2, 6.8–9.2, and 2.0–5.8 log CFU/g, respectively. The Leuconostoccaceae family was present in all Miki products. In samples from two Amami factories, Leuconostoc and Lactococcus were the dominant LABs. Streptococcus and Bacillus were the dominant genera in samples from one Amami factory, while Geobacillus and Anoxybacillus were the dominant genera in samples from the fourth Amami factory. In samples from other regions, lactobacilli were dominant. Among the 14 typical LAB isolates obtained from the agar plate used to determine viable counts, 10 were identified as Leuconostoc lactis. Other isolates were identified as Leuconostoc holzapfelii, Lactoccus raffinolactis, Streptococcus thermophilus, and Limosilactobacillus fermentum. Saccharomyces cerevisiae and Candida lusitaniae isolated as typical yeasts. Geobacillus stearothermophilus and Anoxybacillus sp. were isolated from samples incubated at 60 °C. Differences in the microbiota composition of different processors are attributed to different microorganisms from each factory and the application of heat processing. [Display omitted] • Amami Miki is a fermented rice beverage saccharified with sweet potato amylase. • Leuconostoc, Lactococcus, and Streptococcus were the dominant genera in Miki. • Thermophilic Geobacillus and Anoxybacillus were dominant in one sample. • Ln. lactis, Lc. raffinolactis, and Strep. thermophilus were typical LABs in Miki. • G. stearothermophillus and Anoxybacillus sp. were isolated from samples at 60 °C. [ABSTRACT FROM AUTHOR]

Synbiotics contain health-beneficial bacteria, i.e., probiotics and prebiotics selectively utilized by the probiotics. Herein, three probiotic strains, Leuconostoc lactis CCK940, L. lactis SBC001, and Weissella cibaria YRK005, and the oligosaccharides produced by these strains (CCK, SBC, and YRK, respectively) were used to prepare nine synbiotic combinations. Macrophages (RAW 264.7) were treated with these synbiotic combinations and the corresponding lactic acid bacteria and oligosaccharides alone to evaluate the treatments’ immunostimulatory activities. The level of nitric oxide (NO) production was significantly higher in the macrophages treated with the synbiotics than in those treated with the corresponding probiotic strains and the oligosaccharide alone. The immunostimulatory activities of the synbiotics increased regardless of the probiotic strain and the type of oligosaccharide used. The expressions of tissue necrosis factor-α, interleukin-1β, cyclooxygenase-2, inducible NO synthase genes, and extracellular-signal-regulated and c-Jun N-terminal kinases were significantly higher in the macrophages treated with the three synbiotics than in those treated with the corresponding strains or with the oligosaccharides alone. These results indicate that the synergistic immunostimulatory activities of probiotics and the prebiotics they produced in the studied synbiotic preparations resulted from the activation of the mitogen-activated protein-kinase-signaling pathway. This study suggests the combined use of these probiotics and prebiotics in the development of synbiotic preparations as health supplements.

The patient, who was born spontaneously to a 22-year-old mother as G1 P1 Y1 with a weight of 2605 g at 37 weeks of gestation, had an Activity, Pulse, Grimace, Appearance and Respiration (APGAR) of 8 and 5, respectively, at the first and fifth minutes APGAR 9. Physical examination revealed that the patient's general condition was moderate: body temperature was 36.7 °C, respiratory rate was 68 beats per minute, heart rate was 146 beats per minute, blood pressure was 59/33 mmHg, saturation was 92%, both hemithoraxes participated equally in respiration, consciousness was clear, and the sucking reflex was weak. Because the mother had a history of premature membrane rupture for 22 hours, ampicillin and gentamicin were given intravenously after a blood culture. Leuconostoc lactis was grown in a blood culture sent by the patient. On the 12th day of her hospitalization, the patient was discharged with full oral feeding, had started to weigh regularly, and had good general condition, oral intake, and activity. Leuconostoc species should be kept in mind in vancomycin-resistant gram-positive infections. It should be kept in mind that Leuconostoc lactis may be a cause of Early-onset neonatal sepsis, albeit very rarely. [ABSTRACT FROM AUTHOR]

Abstract Background Probiotics are being considered as valuable microorganisms related to human health. Hu sheep is referred as one of the important sheep breeds in China. Goat milk produced by Hu sheep is characterized with high nutritional value and hypoallergenic in nature. Particularly, this milk contains plenty of milk prebiotic and probiotic bacteria. This study was aimed to scrutinize more bacterial strains from Hu sheep milk with potential probiotic activity. Results Based on 16S rRNA sequence analysis, pool of forty bacterial strains were identified and evaluated their antimicrobial activities against Staphylococcus aureus, enterohemorrhagic Escherichia coli (EHEC), Salmonella typhimurium, Listeria monocytogenes enterotoxigenic E. coli (ETEC) and Aeromonas caviae. Four out of these isolated strains demonstrated their efficient bacteriostatic ability and potential healthy properties. We also examined the safety aspects of these bacterial candidates including three Lactococcus lactis strains (named as HSM-1, HSM-10, and HSM-18) and one Leuconostoc lactis strain (HSM-14), and were further evaluated via in vitro tests, including antimicrobial activity, cell surface characteristics (hydrophobicity, co-aggregation, and self-aggregation), heat treatment, antibiotic susceptibility, simulated transport tolerance in the gastrointestinal tract, and acid/bile tolerance. The obtained results revealed that HSM-1, HSM-10, HSM-14, and HSM-18 showed high survival rate at different conditions for example low pH, presence of bovine bile and demonstrated high hydrophobicity. Moreover, HSM-14 had an advantage over other strains in terms of gastrointestinal tract tolerance, antimicrobial activities against pathogens, and these results were significantly better than other bacterial candidates. Conclusion Hu sheep milk as a source of exploration of potential lactic acid bacteria (LAB) probiotics open the new horizon of probiotics usage from unconventional milk sources. The selected LAB strains are excellent probiotic candidates which can be used for animal husbandry in the future. Rationale of the study was to utilize Hu sheep milk as a source of potential probiotic LABs. The study has contributed to the establishment of a complete bacterial resource pool by exploring the Hu sheep milk microflora.

This research aimed to evaluate and optimize the electrospraying process of microencapsulating the probiotic strain, Leuconostoc lactis (NCDC 200), in a soy protein isolate (SPI) and sunflower oil (SO) combination matrix. In the present study, experimentation was conducted to establish the concentrations of SPI (12–15% w/v), SO (0–5% w/v), and the voltage range (10–15 kV) for the electrospraying operations. Probiotic characteristics, namely, the loss of viability of probiotic cells and encapsulation efficiency, were studied using Box-Behnken design, and specific runs were compared with the freeze-drying process. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were used for microcapsule characterization. The optimized electrospraying process conditions were found to be 13.13% (w/v) SPI, 10.24 kV voltage, and 4.77% (w/v) of SO, for which a viability loss of 0.663 log CFU/g (< 1 log10 CFU/g) and encapsulation efficiency of 92.93% were achieved. Increasing SPI and SO concentration and decreasing the process voltage significantly reduced the viability loss and improved encapsulation efficiency. The study found no significant difference between freeze-drying and electrospraying techniques for encapsulating probiotics in terms of encapsulation efficiency and viability loss for the optimized formulation. The SEM micrographs confirmed the spherical morphology of electrosprayed microcapsules, and FTIR was useful for characterizing and analyzing the protein-lipid interactions in different microcapsules. The present study could establish the protective effect rendered to probiotic cells by combining SPI and SO at specific concentrations during electrospraying. [ABSTRACT FROM AUTHOR]

Leuconostoc lactis is a glycopeptide-resistant, gram-positive, facultative anaerobic coccus isolated from dairy products, whereas Staphylococcus nepalensis is coagulase-negative coccus that has not been identified as human pathogen. We report an instructive case of L. lactis and S. nepalensis bacteremia in a 71-year-old man who experienced Boerhaave syndrome after a meal.

The regularity of the influence of the culture medium (substrate) on the development of microflora at the stage of preliminary fermentation of the model medium on the basis of white cabbage varieties "Parus" was studied. During the research, strains of lactic acid microorganisms Leuconostoc lactis were used. Step-by-step mathematical processing of the experimental data was carried out. Functional dependencies are obtained that most adequately approximate experimental data for modified (MMC) and basic (BMS) model media. Analysis of the experimental data showed that, depending on the type (composition) of the medium, the same species of microorganisms exhibit different dynamics of titer growth. In connection with this, an algorithm was developed to determine the optimal duration of pre-fermentation – «stop points». As a result of the research, it can be seen that the modification of the model medium with the addition of table salt and ascorbic acid to it promotes the formation of positive dynamics of the comparison indicator. This dynamics has three extremes, but only extremes are of practical significance, which were in the interval of the monotonic decrease of the titer. For successful development of the starting culture of the stage of the main fermentation, one of the conditions is a relatively small amount of the titer of the first culture at the end of the preliminary fermentation step to exclude competition. Thus, the position of the «stop-point» position corresponds to the period after the last peak of the comparison indicator. The investigated regularity of the effect of the preliminary cultivation of gram-positive microorganisms on the activity of lactic acid microorganisms in the process of fermentation is topical, since the whole process and the production of high-quality products fully depend on this approach.

The response surface methodology (RSM) was used to obtain a 7.6-fold increase of exopolysaccharide (EPS) 58.1 ± 0.4 g/L produced by Leuconostoc lactis L2 under the condition of sucrose 91.2 g/L, pH 5.8 and NaAc 1.2 g/L. The L2 EPS consisted of 81.2 ± 0.2% total sugar, 13.3 ± 0.4% uronic acid, 0.1 ± 0.01% protein and 0.4 ± 0.01% sulfate. As for chain conformation, congo red test testified the existence of random coil structure. Circular dichroism (CD) revealed that L2 EPS concentration closely related to its hydrogen-bond interactions and chirality. The L2 EPS exhibited moderate scavenging activities and reducing power. It had high viscosity at high concentration, low temperature and acidic to slight alkalic pH (4.0 to 8.0). The high degradation temperature (290.3 °C) implied the high thermal stability of L2 EPS. With the concentration increase (0 to 1.0 mg/mL), the absolute value of zeta potential and particle size of L2 EPS continually raised. The L2 exhibited a degree of hydrophilicity resulting from water contact angle test. Moreover, L2 EPS showed high efficiency in milk solidification. These results collectively conferred L2 EPS a promising commercial application as a safe food additive and antioxidant. • Leu. lactis L2 EPS production increased 7.6-fold by RSM, reaching 58.1 ± 0.4 g/L. • Composition, chain conformation, rheological and hydrophilic properties were assayed. • L2 EPS exhibited high thermal stability and high viscosity under certain conditions. • Concentration closely related to hydrogen-bond interactions and chirality of L2 EPS • L2 PES showed moderate scavenging activity and reducing power, could coagulate milk. [ABSTRACT FROM AUTHOR]

Background: Probiotics are being considered as valuable microorganisms related to human health. Hu sheep is referred as one of the important sheep breeds in China. Goat milk produced by Hu sheep is characterized with high nutritional value and hypoallergenic in nature. Particularly, this milk contains plenty of milk prebiotic and probiotic bacteria. This study was aimed to scrutinize more bacterial strains from Hu sheep milk with potential probiotic activity. Results: Based on 16S rRNA sequence analysis, pool of forty bacterial strains were identified and evaluated their antimicrobial activities against Staphylococcus aureus, enterohemorrhagic Escherichia coli (EHEC), Salmonella typhimurium, Listeria monocytogenes enterotoxigenic E. coli (ETEC) and Aeromonas caviae. Four out of these isolated strains demonstrated their efficient bacteriostatic ability and potential healthy properties. We also examined the safety aspects of these bacterial candidates including three Lactococcus lactis strains (named as HSM-1, HSM-10, and HSM-18) and one Leuconostoc lactis strain (HSM-14), and were further evaluated via in vitro tests, including antimicrobial activity, cell surface characteristics (hydrophobicity, co-aggregation, and self-aggregation), heat treatment, antibiotic susceptibility, simulated transport tolerance in the gastrointestinal tract, and acid/bile tolerance. The obtained results revealed that HSM-1, HSM-10, HSM-14, and HSM-18 showed high survival rate at different conditions for example low pH, presence of bovine bile and demonstrated high hydrophobicity. Moreover, HSM-14 had an advantage over other strains in terms of gastrointestinal tract tolerance, antimicrobial activities against pathogens, and these results were significantly better than other bacterial candidates. Conclusion: Hu sheep milk as a source of exploration of potential lactic acid bacteria (LAB) probiotics open the new horizon of probiotics usage from unconventional milk sources. The selected LAB strains are excellent probiotic candidates which can be used for animal husbandry in the future. Rationale of the study was to utilize Hu sheep milk as a source of potential probiotic LABs. The study has contributed to the establishment of a complete bacterial resource pool by exploring the Hu sheep milk microflora. [ABSTRACT FROM AUTHOR]

Leuconostoc lactis plays a pivotal role in providing a pleasant aroma in fermented foods. In this study, an L. lactis-specific quantitative PCR (qPCR) method was developed by designing species-specific primers using comparative pan-genomic analysis to monitor the microbial populations during food fermentation. As a result, a hypothetical protein-encoding gene, Llac_03470, was selected as a target gene to detect L. lactis using a designed set of primers (NlacF and NlacR). PCR analysis against genomic DNA of various lactic acid bacteria confirmed the specificity of the primers for the detection of genomic DNA of L. lactis strains. By using the primer set, a standard curve for qPCR analysis of L. lactis was established, and no significant differences (p < 0.05) were found in the yields of the genomic DNA recovered from MRS medium and kimchi. In addition, the qPCR was validated to successfully enumerate L. lactis during kimchi fermentation. In conclusion, the newly developed qPCR method in this study can be used to detect L. lactis in fermented kimchi and to monitor the change in its population during the fermentation process. [ABSTRACT FROM AUTHOR]

Dysregulation of immune responses to environmental antigens by the intestine leads to the chronic inflammatory disease, inflammatory bowel disease (IBD). Recent studies have thus sought to identify a dietary component that can inhibit lipopolysaccharide (LPS)‐induced nuclear factor‐kappa beta (NF‐κB) signaling to ameliorate IBD. This study assessed if the lactic acid bacteria (LAB) from kimchi, suppresses the expression of tumor necrosis factor‐alpha (TNF‐α) in peritoneal macrophages induced by LPS. Leuconostoc lactis EJ‐1, an isolate from LAB, reduced the expression of interleukin‐6 (IL‐6) and IL‐1β in peritoneal macrophages induced by LPS. The study further tested whether EJ‐1 alleviates colitis induced by 2,4,6‐trinitrobenzene sulfonic acid (TNBS) in mice. TNBS significantly increased myeloperoxidase (MPO) expression, macroscopic colitis scores, and colon shortening. Oral administration of L. lactis EJ‐1 resulted in an inhibited in TNBS‐induced loss in body weight, colon shortening, MPO activity, and NF‐κB and inducible nitric oxide synthase expression; it also led to a marked reduction in cyclooxygenase‐2 expression. L. lactis EJ‐1 also inhibited the TNBS‐induced expression of TNF‐α, IL‐1β, and IL‐6; however, it induced the expression of IL‐10. The M2 macrophage markers arginase I, IL‐10, and CD206 were elevated by EJ‐1. Collectively, these results suggest that EJ‐1 inhibits the NF‐κB signaling and polarizes M1‐ to M2‐macrophage transition, which help in ameliorating colitis. [ABSTRACT FROM AUTHOR]

Leuconostoc lactis AV1 strain isolated from a Tunisian avocado was characterized as a dextran producer. The promoter PdsrLL and the dsrLL gene encoding the DsrLL dextransucrase responsible for the dextran synthesis were transcriptionally fused to the mCherry coding gene generating the pRCR20 plasmid. Upon plasmid transfer, both AV1n and the dextran non-producing Leuconostoc mesenteroides CM70 became red due to expression of the mCherry from the PdsrLL-dsr-mrfp transcriptional fusion. Characterization of the polymers present in cultures supernatants revealed that the DsrLL encoded from pRCR20 in the recombinant bacteria was able to synthesize dextran. The production of dextran by the DsrLL in AV1n increased in response to low temperature, reaching 10-fold higher levels at 20°C than at 37°C (4.15 g/L versus 0.41 g/L). To analyze if this stress response includes activation at the transcriptional level and if it was only restricted to Leuconostoc, AV1n was transformed with plasmids carrying either the PdsrLL-mrfp fusion or the PdsrLS of Lactobacillus sakei MN1 fused to the mrfp gene, and the influence of temperature and carbon source on expression from the Dsr promoters was monitored by measurement of the mCherry levels. The overall expression analysis confirmed an induction of expression from PdsrLL upon growth at low temperature (20°C versus 30°C and 37°C) in the presence of sugars tested (sucrose, glucose, maltose, and fructose). In addition, the presence of sucrose, the substrate of Dsr, also resulted in activation of expression from PdsrLL. A different behavior was detected, when expression from PdsrLS was evaluated. Similar levels of fluorescence were observed irrespectively of the carbon source or temperature, besides a sequential decrease at 30°C and 20°C, when sucrose was present in the growth medium. In conclusion, the two types of regulation of expression of Dsr presented here revealed two different mechanisms for environmental adaptation of Leuconostoc and Lactobacillus that could be exploited for industrial applications.

Rebaudioside A was modified via glucosylation by recombinant dextransucrase of Leuconostoc lactis EG001 in Escherichia coli BL21 (DE3), forming single O‐α‐D‐glucosyl‐(1″→6′) rebaudioside A with yield of 86%. O‐α‐D‐glucosyl‐(1″→6′) rebaudioside A was purified using HPLC and Diaion HP‐20 and its properties were characterized for possible use as a food ingredient. Almost 98% of O‐α‐D‐glucosyl‐(1″→6′) rebaudioside A was dissolved after 15 days of storage at room temperature, compared to only 11% for rebaudioside A. Compared to rebaudioside A, O‐α‐D‐glucosyl‐(1″→6′) rebaudioside A showed similar or improved acidic or thermal stability in commercial drinks. Thus, O‐α‐D‐glucosyl‐(1″→6′) rebaudioside A could be used as a highly pure and improved sweetener with high stability in commercial drinks. Practical Application: The proposed method can be used to generate glucosyl rebaudioside A by enzymatic glucosylation. Simple glucosyl rebaudioside A exhibited high acid/thermal stability and improved sweetener in commercialized drinks. This method can be applied to obtain high value‐added bioactive compounds by enzymatic modification. [ABSTRACT FROM AUTHOR]

An exopolysaccharide (EPS)-producing bacterium was isolated from the homemade fermentation product of hami melon (Cucumis melo var. saccharinus) and identified as Leuconostoc lactis L2 mainly based on 16S rDNA sequence analysis and the API 50 CHL test. The monosaccharide composition of Leu. lactis L2 EPS was determined to be glucose by gas chromatography (GC), and its molecular weight was 3.7 × 103 kDa by high-performance size exclusion chromatography (HPSEC). The EPS microscopic characteristics were compact, branched and tubular under scanning electron microscopy (SEM). Atomic force microscopy (AFM) showed a smooth and consistent polymeric matrix. The EPS was a linear polymer composed of α-(1 → 6)-linked D-pyranose residues, based on the Fourier transform infrared (FT-IR), 1H, 13C nuclear magnetic resonance (NMR) and heteronuclear single quantum coherence (HSQC) spectra. This EPS exhibited a high water solubility index (WSI) and water holding capacity (WHC) (91.90 ± 2.45% and 509.45 ± 28.59%, respectively), as well as good emulsifying properties with many organic solvents. These results collectively suggest the applicable potential of this EPS in the food, feed and pharmaceutical fields. In this research, an exopolysaccharide (EPS) producing lactic acid bacteria (LAB) strain was isolated and identified as Leuconostoc lactis L2. The monosaccharide composition of the Leu. lactis L2 EPS was glucose, and the Mw was 3.7 × 103 kDa. Microscopically, this EPS exhibited a compact, branched and tubular structure. Topologically, this EPS was a smooth and consistent polymer. The spectra of fourier-transform infrared (FT-IR) and nuclear magnetic resonance (NMR) revealed that Leu. lactis L2 EPS was a linear polymer composed of α-(1 → 6)-linked D-pyranose residue. Moreover, the Leu. lactis L2 EPS exhibited good solubility, water holding capacity and emulsifying property, implying its application potential as hydrocolloids and stabilizer. Unlabelled Image • An exopolysaccharide (EPS) producing LAB Leuconostoc lactis L2 was identified by physiological and biochemical analysis. • This EPS was a linear polymer composed of α-(1 → 6)-linked D-pyranose residue. • Microscopic characteristic of Leu. lactis L2 EPS was compact, branched and tubular. • The EPS showed good water solubility, water holding capacity and emulsibility. [ABSTRACT FROM AUTHOR]

Leuconostoc lactis AV1 strain isolated from a Tunisian avocado was characterized as a dextran producer. The promoter P dsrLL and the dsrLL gene encoding the DsrLL dextransucrase responsible for the dextran synthesis were transcriptionally fused to the mCherry coding gene generating the pRCR20 plasmid. Upon plasmid transfer, both AV1n and the dextran non-producing Leuconostoc mesenteroides CM70 became red due to expression of the mCherry from the P dsrLL-dsr-mrfp transcriptional fusion. Characterization of the polymers present in cultures supernatants revealed that the DsrLL encoded from pRCR20 in the recombinant bacteria was able to synthesize dextran. The production of dextran by the DsrLL in AV1n increased in response to low temperature, reaching 10-fold higher levels at 20°C than at 37°C (4.15 g/L versus 0.41 g/L). To analyze if this stress response includes activation at the transcriptional level and if it was only restricted to Leuconostoc , AV1n was transformed with plasmids carrying either the P dsrLL - mrfp fusion or the P dsrLS of Lactobacillus sakei MN1 fused to the mrfp gene, and the influence of temperature and carbon source on expression from the Dsr promoters was monitored by measurement of the mCherry levels. The overall expression analysis confirmed an induction of expression from P dsrLL upon growth at low temperature (20°C versus 30°C and 37°C) in the presence of sugars tested (sucrose, glucose, maltose, and fructose). In addition, the presence of sucrose, the substrate of Dsr, also resulted in activation of expression from P dsrLL. A different behavior was detected, when expression from P dsrLS was evaluated. Similar levels of fluorescence were observed irrespectively of the carbon source or temperature, besides a sequential decrease at 30°C and 20°C, when sucrose was present in the growth medium. In conclusion, the two types of regulation of expression of Dsr presented here revealed two different mechanisms for environmental adaptation of Leuconostoc and Lactobacillus that could be exploited for industrial applications. [ABSTRACT FROM AUTHOR]

Leuconostoc lactis SBC001, isolated from chive, produces glucansucrase and synthesizes oligosaccharides through its enzymatic activity. This study was conducted to optimize oligosaccharide production using response surface methodology, analyze the structure of purified oligosaccharides, and investigate the prebiotic effect on 24 bacterial and yeast strains and the anti-inflammatory activity using RAW 264.7 macrophage cells. The optimal conditions for oligosaccharide production were a culture temperature of 30 °C and sucrose and maltose concentrations of 9.6% and 7.4%, respectively. Based on 1H-NMR spectroscopic study, the oligosaccharides were identified as gluco-oligosaccharides that consisted of 23.63% α-1,4 glycosidic linkages and 76.37% α-1,6 glycosidic linkages with an average molecular weight of 1137 Da. The oligosaccharides promoted the growth of bacterial and yeast strains, including Lactobacillus plantarum, L. paracasei, L. johnsonii, Leuconostoc mesenteroides, L. rhamnosus, and Saccharomyces cerevisiae. When lipopolysaccharide-stimulated RAW 264.7 cells were treated with the oligosaccharides, the production of nitric oxide was decreased; the expression of inducible nitric oxide synthase, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and IL-10 was suppressed; and the nuclear factor-kappa B signaling pathway was inhibited. In conclusion, the gluco-oligosaccharides obtained from Leu. lactis SBC001 exhibited a prebiotic effect on six bacterial and yeast strains and anti-inflammatory activity in RAW 264.7 macrophage cells.

Leuconostoc species, the common saprophytic bacteria are now emerging as one of the important opportunistic pathogens. There are different risk factors such as compromised immunity, use of vancomycin, parenteral nutrition, and contaminated surgical implanted devices to contribute the human infection. We here present one of the unusual fatal cases of bacteremia in a cancer patient who was infected with a vancomycin-resistant strain of L. lactis.

Diverse exopolysaccharide (EPS)-producing isolates were isolated from an Indian acidic fermented food (Idli) based on the colony morphology. One of the EPS-producing microflora ( Leuconostoc lactis KC117496) was selected for further characterization using FT-IR, HPTLC, AFM, SEM, TGA and XRD analysis. FT-IR spectroscopy revealed the α- d -glucose nature of the EPS. HPTLC analysis confirmed the presence of only glucose monomers, indicating the glucan nature of EPS. NMR spectra revealed the presence of 95% α-(1→6) and 5% branching α-(1→3) linkages. The SEM and AFM showed smooth surfaces and compact structure. TGA results showed higher degradation temperature of 272.01 °C. XRD analysis proved the 33.4% crystalline nature of the EPS. Water solubility index and water-holding capacity of EPS are 14.2 ± 0.208% and 117 ± 7.5%. All the above characteristics of the EPS produced by L. lactis showed that the EPS is of a good-quality polysaccharide with potential applications in the food industry. [ABSTRACT FROM AUTHOR]

Leuconostoc lactis EFEL005 (KACC 91922) isolated from kimchi showed promising probiotic attributes; resistance against acid and bile salts, absence of transferable genes for antibiotic resistance, broad utilization of prebiotics, and no hemolytic activity. To expand our understanding of the species, we generated a draft genome sequence of the strain and analyzed its genomic features related to the aforementioned probiotic properties. Genome assembly resulted in 35 contigs, and the draft genome has 1,688,202 base pairs (bp) with a G+C content of 43.43%, containing 1,644 protein-coding genes and 50 RNA genes. The average nucleotide identity analysis showed high homology (≥ 96%) to the type strain L. lactis KCTC3528, but low homology (≤ 95%) to L. lactis KCTC3773 (formerly L. argentinum). Genomic analysis revealed the presence of various genes for sucrose metabolism (glucansucrases, invertases, sucrose phosphorylases, and mannitol dehydrogenase), acid tolerance (F1F0 ATPases, cation transport ATPase, branched-chain amino acid permease, and lysine decarboxylase), vancomycin response regulator, and antibacterial peptide (Lactacin F). No gene for production of biogenic amines (histamine and tyramine) was found. This report will facilitate the understanding of probiotic properties of this strain as a starter for fermented foods. [ABSTRACT FROM AUTHOR]

Antibiotic-resistant infections remain to be a major issue for all over the world. Although appropriate diagnosis and rapid treatment initiation are crucially important particularly in immunocompromised patients, selection of antibiotics without identification of causative bacteria is often challenging. A 44-year-old woman with acute myeloid leukemia (AML) under myelosuppression suffered from teicoplanin-resistant gram-positive cocci bacteremia. Taking severe neutropenia due to chemotherapy and glycopeptide-resistance into account, teicoplanin was empirically substituted with daptomycin, which led to prompt defervescence. This microorganism later turned out to be Leuconostoc lactis (L. Lactis) , and daptmycin was continued to use based on antimicrobial susceptibility tests. As a result, empiric use of daptomycin successfully controlled glycopeptide-resistant gram-positive cocci bacteremia under neutropenia. This is the first report of daptomycin treatment for L. lactis bacteremia in a patient with AML under neutropenia. Our findings suggest that daptomycin would be a suitable treatment option for glycopeptide-resistant gram-positive cocci bloodstream infections, especially in myelosuppressive patients. [ABSTRACT FROM AUTHOR]

The antimicrobial activity of Leuconostoc lactis BT17, isolated from a spontaneously fermented cereal beverage (boza) against some test microorganisms (Escherichia coli ATCC 25922, Salmonella sp. and Klebsiella pneumoniae) was determined by co-culturing of the strain Leuconostoc lactis BT17 with each of the test microorganisms under static conditions. It was found that the strain Leuconostoc lactis BT17 inhibited the growth of the test microorganisms and no viable cells of Escherichia coli, Salmonella sp. and Klebsiella pneumoniae were detected at the 48-th hour of the co-culturing. The reduction of the number of viable cells in the mixed populations was a result of the produced lactic acid by Leuconostoc lactis BT17 in the culture medium, which modify the conditions unlikely to growth of the test microorganisms. [ABSTRACT FROM AUTHOR]

Leuconostoc is mostly found in food, plants, and dairy products. Due to their innate genomic features, such as the presence of carbohydrate-active enzymes, bacteriocins, and plasmids, Leuconostoc spp. have great biotechnological potential. In this study, four strains were isolated and identified as Leuconostoc mesenteroides SG315 (LA), L. citreum SG255 (LB), L. lactis CCK940 (LC), and L. lactis SBC001 (LD). Comparative analysis was performed using their draft genome sequences. Differences among the four strains were analyzed using the average nucleotide identity, dot plot, and multiple alignments of conserved genomic sequences. Functional profiling revealed 2134, 1917, 1751, and 1816 open reading frames; 2023, 1823, 1655, and 1699 protein-coding genes; 60, 57, 83, and 82 RNA-coding genes; and GC content of 37.5 %, 38.8 %, 43.3 %, and 43.2 %, in LA, LB, LC, and LD, respectively. The total number of genes encoding carbohydrate-active enzymes was 76 (LA), 73 (LB), 57 (LC), and 67 (LD). These results indicate that the four strains shared a large number of genes, but their gene content is different. Furthermore, most genes with unknown functions were observed in the prophage regions of the genome. This study also elucidated the oligosaccharide utilization and folate biosynthesis pathways in Leuconostoc spp. Taken together, our findings provide useful information on the genomic diversity of CAZymes in the four Leuconostoc strains and suggest that these species could be used for potent exploitation., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Author(s).)

Leuconostoc infections are rare and usually occur in immunocompromised patients. This report describes a case of Leuconostoc lactis bacteremia in a patient with coexisting rheumatoid arthritis and tuberculosis arthritis. A disrupted gastrointestinal barrier due to gastrointestinal amyloidosis in long-standing rheumatoid arthritis and tuberculosis arthritis could be a risk factor for Leuconostoc bacteremia. Despite aggressive antibiotic treatment, the patient progressed to septic shock and multi-organ failure. The fatal course might have been caused by rapid progression of gastrointestinal pathology, which could be a risk factor for Leuconostoc bacteremia. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to isolate new bacteriocin-producing lactic acid bacteria from boza and to compare the bacteriocins with those previously described for strains isolated from the same niche. Five bacteriocin-producing lactic acid bacteria (Lactobacillus plantarum ST69BZ, Enterococcus faecium ST62BZ and Leuconostoc lactis ST63BZ, ST611BZ and ST612BZ) were isolated from boza. The bacteriocins of all five isolates inhibited the growth of Enterococcus spp., Escherichia coli, Klebsiella pneumoniae, Lactobacillus spp., Lactococcus lactis subsp. lactis, Listeria spp., Pseudomonas aerouginosa, Staphylococcus spp. and Streptococcus caprinus. The mode of activity of bacteriocins ST69BZ, ST62BZ, ST63BZ, ST611BZ and ST612BZ is bactericidal, as determined against E. faecium HKLHS and L. sakei DSM 20017, respectively. Two of the five studied bacteriocinogenic strains (ST69BZ and ST612BZ) exhibit activity against some fungal cultures. A synergetic effect between bacteriocins ST69BZ, ST62BZ, ST63BZ, ST611BZ and ST612BZ and ciprofloxacin were registered. [Copyright &y& Elsevier]

Strains of Leuconostoc lactis SHO-47 and Le. lactis SHO-54, producing the clinically useful enzyme NAD-specific 6-phosphoglucanate dehydrogenase, were cultivated with a hydrolyzed birch wood xylan as the unique carbon source to produce D-lactic acid for poly(D-lactic acid). In addition to the strains SHO-47 and SHO-54, Lactococcus lactis IO-1, well known as a good xylose-utilizing lactic acid bacterium, was used as a control to confirm the extent of hemicellulose hydrolysis. The fermentation time for lactic acid of strains SHO-47 and SHO-54 was 12 h, and produced respectively 2.3 and 2.2 g/l lactic acid from 8.5 g/l hydrolyzed xylan, whereas the fermentation time of strain IO-1 was 21 h, and produced 1.3 g/l lactic acid. Xylooligosaccharides from xylobiose to xylohexose were utilized more rapidly than xylose in the cultures of strains SHO-47 and SHO-54. However, xylose concentration increased temporarily and then decreased in the culture of strain IO-1. On the other hand, xylooligosaccharides larger than xyloheptaose were not utilized by these three strains. The xylosidase activities of SHO-47, SHO-54, and IO-1 were induced by xylose or a mixture of xylobiose and xylotriose. The xylosidases of these three strains were localized in their cytoplasm. [Copyright &y& Elsevier]