RESUMO
In this study, we conducted sensory evaluation and gas chromatography-mass spectrometry analysis on fermented goat milk samples prepared by 12 strains of lactic acid bacteria (LAB) isolated from goat milk to screen for strains with the ability to reduce the goaty flavor. The bacterial counts of fermented goat milk was 7.07-9.01 log CFU/mL. The electronic nose distinguished fresh goat milk (FGM) and fermented goat milk, and the electronic tongue results showed that Leuconostoc citreum 1, 4, 20, 22, 32, and 57, Latilactobacillus curvatus 144 and 147 imparted fermented goat milk a taste different from FGM. Overall, Leuconostoc citreum 57, Leuconostoc citreum 126, Latilactobacillus curvatus 142, Latilactobacillus curvatus 143, and Latilactobacillus curvatus 147 were screened with the ability to improve the flavor of goat milk. They gave fermented goat milk a goat flavor score lower than or equal to FGM. And the fermented goat milk samples 57, 126, 142, 143, and 147 contained 25, 22, 15, 24, and 17 volatile flavor compounds, respectively, with a greater variety and content of ketones and aldehydes and lower levels of hexanoic acid, octanoic acid, and decanoic acid than FGM. However, the pH and WHC results indicated that the application of these strains as secondary cultures is necessary. Our finding provides basic research data to improve the flavor of goat milk products.
Assuntos
Cabras , Lactobacillales , Leite , Paladar , Animais , Leite/microbiologia , Leite/química , Lactobacillales/metabolismo , Lactobacillales/isolamento & purificação , Ácidos Graxos/análise , Fermentação , Compostos Orgânicos Voláteis/análise , Cromatografia Gasosa-Espectrometria de Massas , Microbiologia de Alimentos , Produtos Fermentados do Leite/microbiologia , Humanos , Aromatizantes/análise , Leuconostoc/metabolismo , Leuconostoc/isolamento & purificaçãoRESUMO
Leuconostoc citreum JZ-002 was extracted from artisanal orange wine. This strain was used to synthesize dextran with a purification extraction of 27.9 g/L. The resulting dextran had a molecular weight of 2.45 × 106 Da. A significant portion, amounting to 64 % of the structure, is constituted by the main chain, with α-(1,6) glycosidic bonds acting as the linkages. In contrast, the branched chain, comprising 34 % of the entire molecule, is characterized by the presence of α-(1,3) glycosidic bonds. The dextransucrase DsrB, believed to be accountable for the formation of the dextran backbone, was successfully cloned into the pET-28a-AcmA vector. The recombinant expression of the enzyme was achieved. Purified recombinant enzymes and immobilized in a single go using the gram-positive enhancer matrix (GEM). The maximum yield of dextran produced by suchimmobilized enzyme was 191.9 g/L. The composition featured a dextran connected via α-(1,6) glycosidic linkages. Molecular weight controlled synthesis was achieved with sucrose concentrations of 100-2000 mM and enzyme concentrations of 320-1280 U. The Mw of the synthesized dextran extended from 4680 to 1,320,000 Da. By controlling the ratio between enzyme concentration and sucrose concentration, dextrans with diverse Mw can be enzymatically generated.
Assuntos
Dextranos , Glucosiltransferases , Leuconostoc , Peso Molecular , Proteínas Recombinantes , Dextranos/química , Dextranos/biossíntese , Glucosiltransferases/química , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Leuconostoc/enzimologia , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Sacarose/químicaRESUMO
Leuconostoc species are regarded as important causes for many infections in immunocompromised patients. In this study, we assessed the characteristics of Leuconostoc spp. causing bacteremia in patients at our center. This observational analysis was conducted in the microbiology laboratory of a tertiary care center in northern India from July 2021 to July 2023. Patients in whom blood culture bottles were positive for Leuconostoc lactis were included in the study. Culture isolates were identified by MALDI-ToF MS as L. lactis and tested for antibiotic sensitivity results by Kirby-Bauer disk diffusion method. Demographic and clinical details were collected and analyzed. During the study period, 6,742 blood culture bottles flagged positive. Among these, L. lactis was isolated from 14 (0.21%) patients. The median patient age was 34 years. The male-to-female ratio was 2.5:1. All the patients with L. lactis bacteremia had an underlying condition leading to immunosuppression (e.g., carcinoma and chronic kidney disease). All the patients with L. lactis bacteremia had an intravascular device present at the time of bacteremia. All isolates in the study were sensitive to doxycycline, high level gentamicin, minocycline, ampicillin-sulbactam, and linezolid. Mortality was attributed to bacteremia by L. lactis in five patients. Appropriate and timely identification of the Leuconostoc species is important for the clinician to tailor regimens for the patients.
Assuntos
Antibacterianos , Bacteriemia , Leuconostoc , Centros de Atenção Terciária , Humanos , Bacteriemia/microbiologia , Bacteriemia/epidemiologia , Bacteriemia/tratamento farmacológico , Índia/epidemiologia , Masculino , Feminino , Leuconostoc/isolamento & purificação , Leuconostoc/efeitos dos fármacos , Adulto , Antibacterianos/uso terapêutico , Antibacterianos/farmacologia , Pessoa de Meia-Idade , Infecções por Bactérias Gram-Positivas/microbiologia , Infecções por Bactérias Gram-Positivas/epidemiologia , Infecções por Bactérias Gram-Positivas/tratamento farmacológico , Infecções por Bactérias Gram-Positivas/mortalidade , Adulto Jovem , Testes de Sensibilidade Microbiana , IdosoRESUMO
Bacterial cellulose (BC) has been found extensive applications in diverse domains for its exceptional attributes. However, the lack of antibacterial properties hampers its utilization in food and biomedical sectors. Leucocin, a bacteriocin belonging to class IIa, is synthesized by Leuconostoc that demonstrates potent efficacy against the foodborne pathogen, Listeria monocytogenes. In the current study, co-culturing strategy involving Kosakonia oryzendophytica FY-07 and Leuconostoc carnosum 4010 was used to confer anti-listerial activity to BC, which resulted in the generation of leucocin-containing BC (BC-L). The physical characteristics of BC-L, as determined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), were similar to the physical characteristics of BC. Notably, the experimental results of disc diffusion and growth curve indicated that the BC-L film exhibited a potent inhibitory effect against L. monocytogenes. Scanning electron microscopy (SEM) showed that BC-L exerts its bactericidal activity by forming pores on the bacterial cell wall. Despite the BC-L antibacterial mechanism, which involves pore formation, the mammalian cell viability remained unaffected by the BC-L film. The measurement results of zeta potential indicated that the properties of BC changed after being loaded with leucocin. Based on these findings, the anti-listerial BC-L generated through this co-culture system holds promise as a novel effective antimicrobial agent for applications in meat product preservation and packaging.
Assuntos
Antibacterianos , Celulose , Listeria monocytogenes , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/crescimento & desenvolvimento , Antibacterianos/farmacologia , Antibacterianos/química , Celulose/química , Celulose/farmacologia , Celulose/biossíntese , Técnicas de Cocultura , Testes de Sensibilidade Microbiana , Leuconostoc/metabolismo , Bacteriocinas/farmacologia , Bacteriocinas/químicaRESUMO
The aim of this research was to find out the effect of different combinations of starter and non-starter cultures on the proteolysis of Castellano cheese during ripening. Four cheese batches were prepared, each containing autochthonous lactobacilli and or Leuconostoc, and were compared with each other and with a control batch, that used only a commercial starter. To achieve this, nitrogen fractions (pH 4.4-soluble nitrogen and 12 % trichloroacetic acid soluble nitrogen, polypeptide nitrogen and casein nitrogen), levels of free amino acids and biogenic amines were assessed. Texture and microstructure of cheeses were also evaluated. Significant differences in nitrogen fractions were observed between batches at different stages of ripening. The free amino acid content increased throughout the cheese ripening process, with a more significant increase occurring after the first 30 days. Cheeses containing non-starter lactic acid bacteria exhibited the highest values at the end of the ripening period. Among the main amino acids, GABA was particularly abundant, especially in three of the cheese batches at the end of ripening. The autochthonous lactic acid bacteria were previously selected as non-producers of biogenic amines and this resulted in the absence of these compounds in the cheeses. Analysis of the microstructure of the cheese reflected the impact of proteolysis. Additionally, the texture profile analysis demonstrated that the cheese's hardness intensified as the ripening period progressed. The inclusion of autochthonous non-starter lactic acid bacteria in Castellano cheese production accelerated the proteolysis process, increasing significantly the free amino acids levels and improving the sensory quality of the cheeses.
Assuntos
Aminoácidos , Aminas Biogênicas , Queijo , Proteólise , Queijo/microbiologia , Queijo/análise , Aminoácidos/análise , Aminoácidos/metabolismo , Aminas Biogênicas/análise , Microbiologia de Alimentos , Manipulação de Alimentos/métodos , Leuconostoc/metabolismo , Leuconostoc/crescimento & desenvolvimento , Lactobacillus/metabolismo , Lactobacillus/crescimento & desenvolvimento , Nitrogênio/análise , Qualidade dos Alimentos , FermentaçãoRESUMO
Lactic Acid Bacteria (LAB) are predominantly probiotic microorganisms and the most are Generally Recognized As Safe (GRAS). LAB inhabit in the human gut ecosystem and are largely found in fermented foods and silage. In the last decades, LAB have also has been found in plant microbiota as a new class of microbes with probiotic activity to plants. For this reason, today the scientific interest in the study and isolation of LAB for agronomic application has increased. However, isolation protocols from complex samples such as plant tissues are scarce and inefficient. In this study, we developed a new protocol (CLI, Complex samples LAB Isolation) which yields purified LAB from plants. The sensitivity of CLI protocol was sufficient to isolate representative microorganisms of LAB genera (i.e. Leuconostoc, Lactococcus and Enterococcus). CLI protocol consists on five steps: i) sample preparation and pre-incubation in 1% sterile peptone at 30 °C for 24-48 h; ii) Sample homogenization in vortex by 10 min; iii) sample serial dilution in quarter-strength Ringer solution, iv) incubation in MRS agar plates with 0.2% of sorbic acid, with 1% of CaCO3, O2 < 15%, at pH 5.8 and 37 °C for 48 h.; v) Selection of single colonies with LAB morphology and CaCO3-solubilization halo. Our scientific contribution is that CLI protocol could be used for several complex samples and represents a useful method for further studies involving native LAB.
Assuntos
Lactobacillales , Lactobacillales/isolamento & purificação , Lactobacillales/classificação , Plantas/microbiologia , Leuconostoc/isolamento & purificação , Probióticos/isolamento & purificação , Lactococcus/isolamento & purificação , Enterococcus/isolamento & purificação , Ácido Láctico/metabolismoRESUMO
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.
Assuntos
Fermentação , Glucanos , Leuconostoc , Solubilidade , Leite de Soja , Água , Leuconostoc/metabolismo , Leite de Soja/química , Água/química , Viscosidade , Glucanos/química , Fenômenos QuímicosRESUMO
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.
Assuntos
Bacillus , Dictyostelium , Leuconostoc mesenteroides , Penaeidae , Probióticos , Vibrio parahaemolyticus , Animais , Resistência à Doença , Muramidase/metabolismo , Leuconostoc , Dextranos/metabolismo , Vibrio parahaemolyticus/fisiologia , Dieta , Imunidade InataRESUMO
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.
Assuntos
Leuconostoc mesenteroides , Leuconostoc/química , Iogurte , Espectroscopia de Infravermelho com Transformada de Fourier , Polissacarídeos Bacterianos/química , MonossacarídeosRESUMO
Six lactic acid bacteria (LAB) isolated from Algerian sheep's milk, traditional butter, date palm sap and barley, which produce dextran, mannitol, oligosaccharides and vitamin B2 have been characterized. They were identified as Leuconostoc mesenteroides (A4X, Z36P, B12 and O9) and Liquorilactobacillus mali (BR201 and FR123). Their exopolysaccharides synthesized from sucrose by dextransucrase (Dsr) were characterized as dextrans with (1,6)-D-glucopyranose units in the main backbone and branched at positions O-4, O-2 and/or O-3, with D-glucopyranose units in the side chain. A4X was the best dextran producer (4.5 g/L), while the other strains synthesized 2.1-2.7 g/L. Zymograms revealed that L. mali strains have a single Dsr with a molecular weight (Mw) of ~ 145 kDa, while the Lc. mesenteroides possess one or two enzymes with 170-211 kDa Mw. As far as we know, this is the first detection of L. mali Dsr. Analysis of metabolic fluxes from sucrose revealed that the six LAB produced mannitol (~ 12 g/L). The co-addition of maltose-sucrose resulted in the production of panose (up to 37.53 mM), an oligosaccharide known for its prebiotic effect. A4X, Z36P and B12 showed dextranase hydrolytic enzymatic activity and were able to produce another trisaccharide, maltotriose, which is the first instance of a dextranase activity encoded by Lc. mesenteroides strains. Furthermore, B12 and O9 grew in the absence of riboflavin (vitamin B2) and synthesized this vitamin, in a defined medium at the level of ~ 220 µg/L. Therefore, these LAB, especially Lc. mesenteroides B12, are good candidates for the development of new fermented food biofortified with functional compounds.
Assuntos
Leuconostoc mesenteroides , Animais , Ovinos , Dextranos/metabolismo , Dextranase/química , Dextranase/metabolismo , Manitol/metabolismo , Mali , Glucosiltransferases/metabolismo , Oligossacarídeos/química , Sacarose/metabolismo , Vitaminas/metabolismo , Leuconostoc/metabolismoRESUMO
The current study was conducted to statistically compare the SYBR® Green quantitative polymerase chain reaction (qPCR) assay and the conventional plate counting (PC) method to construct growth curves of a cocktail of Weissella viridescens in pure culture under different isothermal storage conditions (4, 8, 14, and 30 °C) and in mixed culture with Leuconostoc mesenteroides at 8 °C. The efficiency and specificity of the qPCR standard curves were confirmed, and both methods were adequate to quantify the growth kinetics of W. viridescens at all isothermal temperatures, demonstrating a good correlation and agreement. The efficiencies of the standard curves varied between 98% and 102%. The SYBR® Green qPCR assay was also able to differentiate the growth curves of W. viridescens and L. mesenteroides in the mixed culture at 8 °C. Additionally, the SYBR® Green qPCR method was considered a faster and more sensitive alternative to construct growth curves under different isothermal conditions and differentiate morphologically similar lactic acid bacteria. Overall, the results suggest that the SYBR® Green qPCR method is a reliable and efficient tool to study microbial growth kinetics in pure and mixed cultures.
Assuntos
Lactobacillales , Leuconostoc mesenteroides , Weissella , Lactobacillus , Weissella/genética , Leuconostoc/genéticaRESUMO
In this study, Leuconostoc citreum BH10, an endophytic strain, was isolated from aseptically collected xylem sap of birch for the first time, and its exopolysaccharide (LCEPS) production was up to 46.31 g/L in glucan producing medium. The produced LCEPS was purified to obtain two water-soluble fractions, named as LCEPS-1 and LCEPS-2, respectively. The major fraction LCEPS-1 was characterized to be comprised of glucose with average molecular weight of 6.34 × 106 Da. The structure of LCEPS-1 was investigated by spectroscopy analysis, which revealed that LCEPS-1 was identified with containing 90.45 % α-(1,6) linkages in the main chains and 9.55 % α-(1,3) branch linkages. The scanning electron microscope results demonstrated that the dried LCEPS-1 appeared porous surface overlaid with an irregular glittering. The water solubility index (WSI) and water holding capacity (WHC) of LCEPS-1 were 88.02 ± 1.69 % and 241.43 ± 6.38 %, respectively. Besides, it exhibited high thermal stability as well as fine antioxidant activities. Taken together, the results indicated that LCEPS-1 could have good potentiality to be applied in fields of foods, cosmetics, nutraceuticals and pharmaceutical industries as the natural agent.
Assuntos
Betula , Polissacarídeos Bacterianos , Polissacarídeos Bacterianos/química , Glucose , Leuconostoc/química , Água/químicaRESUMO
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.
Assuntos
Bacteriemia , Infecções por Bactérias Gram-Positivas , Neoplasias , Humanos , Bacteriemia/microbiologia , beta-Lactamas/farmacologia , Cateteres de Demora/microbiologia , Glicopeptídeos/efeitos adversos , Infecções por Bactérias Gram-Positivas/diagnóstico , Infecções por Bactérias Gram-Positivas/tratamento farmacológico , Infecções por Bactérias Gram-Positivas/etiologia , Leuconostoc , Neoplasias/complicaçõesRESUMO
The colour of meat typically fades as it decays. However, it has been observed that certain vacuum-packaged spoiled hams can maintain a pink colour even when the packaging is bulged. A large amount of Zinc protoporphyrin IX (ZnPP) was found in these hams, compared to fresh red hams or spoiled and grey hams. Combined with high-throughput sequencing and cultural isolation, the potential cultures of Leuconostoc mesenteroides S-13 (LM), Leuconostoc citreum OCLC11 (LC), and Leuconostoc mesenteroides subsp. IMAU:80679 (LS) were selected based on their ability to produce ZnPP. Subsequently, these cultures were introduced into a fermented sausage model to assess their effect on colour conversion. The analysis of absorption and fluorescent spectra showed that Nitrite sausages contained nitrosyl heme pigment, while bacteria-inoculated sausages were predominantly composed of ZnPP. In addition, the a* value of the LS sausage was close to the Nitrite group at the end of fermentation, significantly higher than control, indicating the effect of bacterial metabolism on the redness. Meanwhile, the Ferrochelatase (FECH) activity of LM, LC and LS groups were 140 ± 13, 113 ± 16 and 201 ± 20 U/g sausage, respectively, providing a potential method on compensating for nitrite/nitrate substitution based on the presence of ZnPP in meat products.
Assuntos
Leuconostoc mesenteroides , Carne de Porco , Nitritos , Vácuo , LeuconostocRESUMO
Leuconostoc lactis strain DMLL10 was isolated from kimchi, a fermented vegetable, as a starter candidate through safety and technological assessments. Strain DMLL10 was susceptible to ampicillin, chloramphenicol, clindamycin, erythromycin, gentamicin, kanamycin, streptomycin, and tetracycline. It did not show any hemolytic activity. Regarding its phenotypic results related to its safety properties, genomic analysis revealed that strain DMLL10 did not encode for any toxin genes such as hemolysin found in the same genus. It did not acquire antibiotic resistance genes either. Strain DMLL10 showed protease activity on agar containing NaCl up to 3%. The genome of DMLL10 encoded for protease genes and possessed genes associated with hetero- and homo-lactic fermentative pathways for lactate production. Finally, strain DMLL10 showed antibacterial activity against seven common foodborne pathogens, although bacteriocin genes were not identified from its genome. These results indicates that strain DMLL10 is a novel starter candidate with safety, enzyme activity, and bacteriocin activity. The complete genomic sequence of DMLL10 will contribute to our understanding of the genetic basis of probiotic properties and allow for assessment of the effectiveness of this strain as a starter or probiotic for use in the food industry.
Assuntos
Bacteriocinas , Alimentos Fermentados , Leuconostoc , Fermentação , Antibacterianos/farmacologia , Antibacterianos/metabolismo , Bacteriocinas/genética , Bacteriocinas/farmacologia , Bacteriocinas/metabolismo , Alimentos Fermentados/microbiologia , República da Coreia , Peptídeo Hidrolases/genética , Peptídeo Hidrolases/metabolismo , Microbiologia de AlimentosRESUMO
Leuconostoc spp. is often regarded as the flavor producer, responsible for the production of acetoin and diacetyl in dairy cheese. In this study, we investigate seven plant-derived Leuconostoc strains, covering four species, in their potential as a lyophilized starter culture for flavor production in fermented soy-based cheese alternatives. We show that the process of lyophilization of Leuconostoc can be feasible using a soy-based lyoprotectant, with survivability up to 63% during long term storage. Furthermore, the storage in this media improves the subsequent growth in a soy-based substrate in a strain specific manner. The utilization of individual raffinose family oligosaccharides was strain dependent, with Leuconostoc pseudomesenteroides NFICC99 being the best consumer. Furthermore, we show that all investigated strains were able to produce a range of volatile flavor compounds found in dairy cheese products, as well as remove certain dairy off-flavors from the soy-based substrate like hexanal and 2-pentylfuran. Also here, NFICC99 was strain producing most cheese-related volatile flavor compounds, followed by Leuconostoc mesenteroides NFICC319. These findings provide initial insights into the development of Leuconostoc as a potential starter culture for plant-based dairy alternatives, as well as a promising approach for generation of stable, lyophilized cultures.
Assuntos
Laticínios , Leuconostoc , Fermentação , Leuconostoc/metabolismo , Concentração de Íons de Hidrogênio , Açúcares/metabolismoRESUMO
2-O-α-D-glucopyranosyl-sn-glycerol (2-αGG) is a high value product with wide applications. Here, an efficient, safe and sustainable bioprocesses for 2-αGG production was designed. A novel sucrose phosphorylase (SPase) was firstly identified from Leuconostoc mesenteroides ATCC 8293. Subsequently, SPase mutations were processed with computer-aided engineering, of which the activity of SPaseK138C was 160% higher than that of the wild-type. Structural analysis revealed that K138C was a key functional residue moderating substrate binding pocket and thus influences catalytic activity. Furthermore, Corynebacterium glutamicum was employed to construct microbial cell factories along with ribosome binding site (RBS) fine-tuning and a two-stage substrate feeding control strategy. The maximum production of 2-αGG by these combined strategies reached 351.8 g·L-1 with 98% conversion rate from 1.4 M sucrose and 3.5 M glycerol in a 5-L bioreactor. This was one of the best performance reported in single-cell biosynthesis of 2-αGG, which paved effective ways for industrial-scale preparation of 2-αGG.
Assuntos
Leuconostoc mesenteroides , Leuconostoc mesenteroides/metabolismo , Glicerol , Sacarose/metabolismo , Biotransformação , Leuconostoc/genética , Leuconostoc/metabolismoRESUMO
This paper describes the structural elucidation of Leuconostoc mesenteroides P35 exopolysaccharide (EPS-LM). Ln. mesenteroides P35 strain was isolated from a French goat cheese for its capacity to produce EPS increasing the viscosity of a whey-based fermentation medium. The chemical structure of EPS-LM analysis was elucidated by determination of optical rotation degree, macromolecular characterization, sugar units and methylation analyses, FT-IR, 1D NMR spectroscopy (1H and 13C NMR), 2D NMR spectroscopy (1H1H COSY, HSQC and HMBC). EPS-LM was a high molecular weight (ranging from 6.7 × 106 Da to 9.9 × 106 Da) dextran that is composed of only d-glucose units containing α (1 â 6) linkages and paltry α (1 â 3) branches. Since polysaccharide-protein interactions can be exploited to control and design food matrices, EPS-LM interactions with bovine serum albumin (the main constituent of bovine plasma) were investigated by surface plasmon resonance (SPR). Kinetic properties of EPS-LM binding with immobilized BSA via showed an increase of EPS-LM affinity (equilibrium constant (Kd)) for BSA from (2.50 ± 0.01) × 10-5 M-1 at 298 K to (9.21 ± 0.05) × 10-6 M-1 at to 310 K. The thermodynamic parameters revealed that van der Waals and hydrogen binding forces play a major role in the interaction of EPS-LM with BSA. However, EPS-LM-BSA interaction was non-spontaneous, entropy driven and an EPS-LM - BSA binding process was endothermic (ΔG > 0). The structural findings suggested that Ln. mesenteroides P35 α-D-glucan might find widespread technological applications in the biopolymer, medical and food industries.
Assuntos
Leuconostoc mesenteroides , Ressonância de Plasmônio de Superfície , Leuconostoc mesenteroides/metabolismo , Soroalbumina Bovina/química , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Leuconostoc/metabolismoRESUMO
Kimchi is a traditional Korean fermented vegetable that is stored and fermented at low temperatures. However, kimchi lactic acid bacteria (LAB) are typically isolated under mesophilic conditions, which may be inappropriate for isolating the diverse LAB. Therefore, this study investigated the suitable conditions for isolating various LAB from kimchi. Here, LAB were isolated from four kimchi samples using MRS, PES, and LBS media and varying isolation temperatures (30, 20, 10, and 5°C). Then, MRS was selected as the suitable medium for LAB isolation. A comparison of culture-dependent and culture-independent approaches indicated that 5°C was not a suitable isolation temperature. Thus, the number and diversity of LAB were determined at 30, 20, and 10°C using 12 additional kimchi samples to elucidate the effect of isolation temperature. With the exception of two samples, most samples did not substantially differ in LAB number. However, Leuconostoc gelidum, Leuconostoc gasicomitatum, Leuconostoc inhae, Dellaglioa algida, Companilactobacillus kimchiensis, Leuconostoc miyukkimchii, Leuconostoc holzapfelii, and Leuconostoc carnosum were isolated only at 10 and 20°C. The growth curves of these isolates, except Leu. holzapfelii and Leu. carnosum, showed poor growth at 30°C. This confirmed their psychrotrophic characteristics. In Weissella koreensis, which was isolated at all isolation temperatures, there was a difference in the fatty acid composition of membranes between strains that could grow well at 30°C and those that could not. These findings can contribute to the isolation of more diverse psychrotrophic strains that were not well isolated under mesophilic temperatures.
Assuntos
Alimentos Fermentados , Lactobacillales , Temperatura , Fermentação , Características Culturais , Leuconostoc , Microbiologia de AlimentosRESUMO
The Kimoto-style fermentation starter is a traditional preparation method of sake brewing. In this process, specific microbial transition patterns have been observed within nitrate-reducing bacteria and lactic acid bacteria during the production process of the fermentation starter. We have characterized phylogenetic compositions and diversity of the bacterial community in a sake brewery performing the Kimoto-style fermentation. Comparing the time-series changes with other sake breweries previously reported, we found a novel type of Kimoto-style fermentation in which the microbial transition differed significantly from other breweries during the fermentation step. Specifically, the lactic acid bacteria, Leuconostoc spp. was a predominant species in the late stage in the preparation process of fermentation starter, on the other hand, Lactobacillus spp., which plays a pivotal role in other breweries, was not detected in this analysis. The discovery of this new variation of microbiome transition in Kimoto-style fermentation has further deepened our understanding of the diversity of sake brewing.