Exopolysaccharide-producing Strains Research Articles

Antilisterial and antioxidant exopolysaccharide from Enterococcus faecium PCH.25 isolated from cow butter: characterization and probiotic potential.

Exopolysaccharides produced by lactic acid bacteria have gained attention for their potential health benefits and applications in functional foods. This study explores the isolation and characterization of a novel exopolysaccharide-producing strain from dairy products. The aim was to evaluate its probiotic potential and investigate the properties of the produced exopolysaccharide. A strain identified as Enterococcus faecium PCH.25, isolated from cow butter, demonstrated exopolysaccharide production. The study's novelty lies in the comprehensive characterization of this strain and its exopolysaccharide, revealing unique properties with potential applications in food, cosmetic, and pharmaceutical industries. The E. faecium PCH.25 strain exhibited strong acid tolerance, with a 92.24% viability rate at pH 2 after 2h of incubation. It also demonstrated notable auto-aggregation (85.27% after 24h) and co-aggregation abilities, antibiotic sensitivity, and absence of hemolytic activity, suggesting its probiotic potential. The exopolysaccharide produced by this strain showed bactericidal activity (MIC and MBC = 1.8mg/ml) against Listeria monocytogenes and antioxidant properties (22.8%). Chemical analysis revealed a heteropolysaccharide composed of glucose and fructose monomers, with various functional groups contributing to its bioactivities. Physical characterization of the exopolysaccharide indicated thermal stability up to 270°C, a negative zeta-potential (-27 mV), and an average particle size of 235nm. Scanning electron microscopy and energy dispersive X-ray analysis revealed a smooth, nonporous structure primarily composed of carbon and oxygen, with an amorphous nature. These findings suggest that the exopolysaccharide from E. faecium PCH.25 has potential as a natural antibacterial and antioxidant polymer for use in functional foods, cosmetics, and pharmaceuticals.

Genomic characterization and probiotic potential assessment of an exopolysaccharide-producing strain Pediococcus pentosaceus LL-07 isolated from fermented meat

BackgroundThe genomic information available for Pediococcus pentosaceus is primarily derived from fermented fruits and vegetables, with less information available from fermented meat. P. pentosaceus LL-07, a strain isolated from fermented meat, has the capability of producing exopolysaccharides (EPS). To assess the probiotic attributes of P. pentosaceus LL-07, we conducted whole-genome sequencing (WGS) using the PacBio SequelIIe and Illumina MiSeq platforms, followed by in vitro experiments to explore its probiotic potential.ResultsThe genome size of P. pentosaceus LL-07 is 1,782,685 bp, comprising a circular chromosome and a circular plasmid. Our investigation revealed the absence of a CRISPR/Cas system. Sugar fermentation experiments demonstrated the characteristics of carbohydrate metabolism. P. pentosaceus LL-07 contains an EPS synthesis gene cluster consisting of 13 genes, which is different from the currently known gene cluster structure. NO genes associated with hemolysis or toxin synthesis were detected. Additionally, eighty-six genes related to antibiotic resistance were identified but not present in the prophage, transposon or plasmid. In vitro experiments demonstrated that P. pentosaceus LL-07 was comparable to the reference strain P. pentosaceus ATCC25745 in terms of tolerance to artificial digestive juice and bile, autoaggregation and antioxidation, and provided corresponding genomic evidence.ConclusionThis study confirmed the safety and probiotic properties of P. pentosaceus LL-07 via complete genome and phenotype analysis, supporting its characterization as a potential probiotic candidate.

Optimizing Drought Resilience in Okra (Abelmoschus esculentus) Through Synergistic Actions of Drought-Tolerant Rhizobacterial Strains and Brassinosteroids Hormone Application: A Jar Trial Study

<p>The study addresses the critical issue of water scarcity in agriculture, which causes significant losses by disrupting plant-water connections and increasing oxidative damage to biological components. In this study, we evaluated the synergistic potential of pre-isolated and identified exopolysaccharide-producing strains (ZE15 and ZE11) in combination with the drought-alleviating hormone Brassinosteroids (BR) to boost okra development under PEG-6000-induced drought stress. The experiment was carried out in a controlled environment at the Soil Microbiology and Biotechnology Laboratory. It used a completely randomized design with factorial arrangements and three replications. Individual rhizobacterial strains were evaluated and also used in a consortium (ZE15+ZE11) at two different Brassinosteroids (BR) concentrations (10-4 M and 10-8 M). The results showed that the consortium of (ZE15+ZE11) with foliar spray of BR (10-8 M) greatly increased okra production. Under both control and drought stress conditions, shoot length (37 and 34%), root length (41 and 40%), root surface area (32, 34%), and root volume (35 and 33%) improved significantly compared to the control group. Furthermore, this treatment demonstrated the most promising results in alleviating drought-induced oxidative damage by improving antioxidant defense mechanisms. Key enzyme activities, such as MDA (30 and 31%), GR (32 and 30%), SOD (36 and 37%), and CAT (31 and 34%), rose significantly under both control and drought stress conditions when compared to the control. To summarize, the use of drought-tolerant bacteria in concert with plant growth hormone provides a synergistic approach to mitigating the negative impacts of drought, resulting in considerable gains in okra growth and antioxidant defenses. This technique shows promise as a way to increase agricultural productivity in arid and semi-arid areas.</p>

The Potential of Weissella confusa K2 Isolated from Longan (Dimocarpus longan) Fruit as High Exopolysaccharide-Producing Strain

Isolation of Lactic Acid Bacteria (LAB) from various sources has previously been carried out to obtain strains that produce high of exopolysaccharide (EPS). Isolate K2, which was LAB isolated from longan (Dimocarpus longan) fruit, can produce EPS. This study aimed to identify isolate K2, and evaluated the effect of supplementation carbon sources (glucose, fructose, sucrose, and lactose) and pH of media (4, 5, 6, 7, and 8) on EPS production. Isolate K2 was identified as Weissella confusa molecularly based on 16S rDNA, the type of carbon source, and the pH of media had significant effects (P<0.05) on EPS production. W. confusa K2 produced EPS that was highest on media with the supplementation of sucrose as a carbon source and produced the lowest EPS on lactose. The amount of EPS produced by W. confusa K2 under alkaline was higher than under acidic, the highest EPS of 47.703 g/L at pH 8 and the lowest EPS at pH 4 of 1.858 g/L. The physical properties showed EPS has good solubility in water with the solubility and Water Holding Capacity (WHC) at 40.533% and 354% respectively. Based on Surface morphology of EPS with Scanning Electron Microscope (SEM) analysis, the surface structure of EPS was a porous polymer matrix. Fourier Transform Infrared Spectrophotometer (FTIR) results of EPS showed the presence of absorption bands as characteristic of carbohydrates, such as the presence of O-H, C-H, C=O, C=C, C-O-C groups, and glycosidic bonds.

Effect of LAB starters on technological and functional properties of composite carob and chickpea flour plant-based gurt

Carob pulp powder and chickpea flour were used as ingredients in the formulation of a plant-based fermented beverage (gurt). Three different exopolysaccharide-producing strains (Levilactobacillus brevis AM7, Weissella confusa CK15, and Pediococcus claussenii DSM 14800) were used as starters to obtain a gurt rich in fiber and protein. L. brevis AM7 showed the fastest and more intense acidification, whereas W. confusa CK15 induced the highest viscosity increase (reaching up to 3000 mPa × s) due to the in-situ synthesis of dextran. Gurts were characterized by a high antioxidant activity (86.37 %) mainly due to the ingredients used, since it was not affected by fermentation. Depending on the strain, fermentation determined a significant decrease of gurts starch hydrolysis index. Overall, the microbiological, biochemical, and rheological features were retained during the two-weeks refrigerated storage. All exopolysaccharide-producing strains resulted suitable starters for gurt production, but their metabolic traits reflected different fermentation performances and product features. Overall, W. confusa CK15 resulted an efficient dextran producer whereas, based on the growth and acidification kinetics, L. brevis AM7 showed optimal adaptation to carob/chickpea substrate and pro-technological performance.

Structure and effect onBifidobacterium longumof exopolysaccharide produced byWeissella cibariausing cost-effective substrates

AbstractMaize straw, an abundant agricultural residue, has potential as an eco-friendly resource. The aim of this study was to investigate the structure and effect on Bifidobacterium longum of exopolysaccharide produced by Weissella cibaria using maize straw as a carbon source. In this work, an exopolysaccharide-producing strain was isolated from vegetable juice, which was identified as W. cibaria. Our results demonstrated that exopolysaccharide produced by W. cibaria is a linear glucan containing an α-1,6 glycosidic bond with a molecular weight of 9462 Da. In addition, scanning electron microscopy of exopolysaccharide from W. cibaria revealed the flake structures. In vitro assays showed that the exopolysaccharide from W. cibaria has the ability to stimulate the proliferation of B. longum strain and its metabolism to produce acetic acid. This work provides a scientific reference for the potential application of maize straw and a new insight into an eco-friendly carbon source to produce exopolysaccharide.

Bacteria productora de exopolisacárido mejora la sobrevivencia y el perfil proteolítico de Lactobacillus rhamnosus gg adicionado a un queso semimadurado

Currently, the interest of the food industry on the use of probiotics in order to provide beneficial effects is increasing. However, one limitation is getting microorganisms to survive in food matrices. In this work, protective effect of exopolysaccharide produced by Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772 on Lactobacillus rhamnosus GG survival during semi-ripening of cheese, was analyzed. Ripening was carried out at 14 ° C for 28 days in a controlled RH chamber. Scanning electron microscopy (SEM) was performed to determine interactions of probiotic with the exopolysaccharide. During ripening process, the proteolytic activity was determined through TNBS, SDS-PAGE and size exclusion-HPLC techniques. Viability of probiotic was measured by plate count. Cheese inoculated with both strains showed an improvement in probiotic survival. Exopolysaccharide was shown to have an effect on protein aggregation and cheese structural uniformity. Micrographs revealed a direct interaction between probiotic and exopolysaccharide. Proteolytic capacity did not decrease, and the generation and decrease of low molecular weight peptides (less than 3 kDa) was verified throughout the ripening process. Thus, using an exopolysaccharide-producing strain during cheese ripening has a positive effect on probiotic survival when they are used as starter cultures.

Diversity and technological characterization of Pediococcus pentosaceus strains isolated from Nigerian traditional fermented foods

The diversity and technological properties of Pediococcus pentosaceus strains, isolated from some traditional fermented foods in Nigeria, were studied with the aim of selecting suitable strains as a starter and/or adjunct cultures. Eighteen lactic acid bacteria isolates from ogi, gari and fufu were presumptively identified as Pediococcus species using the conventional methods, these isolates were screened for technological and safety properties such as exopolysaccharide production, acidifying activity, antimicrobial activity, and biogenic amine production. The LAB isolates were further differentiated by using internal transcribed spacer-restriction fragment length polymorphism (ITS-RFLP), randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) and pulsed-field gel electrophoresis (PFGE) molecular typing techniques. The Pediococcus sp. displayed antimicrobial activities against Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecium. They all had high acidifying activities and were able to reduce the pH to lower than 5.20 after 24 h. Pediococcus pentosaceus OF31 showed interesting potential technological characteristics due to its antimicrobial activity and exopolysaccharide production. The combination of RAPD-PCR (using primers OPA20 and M13) and PFGE-SfiI genotypic fingerprinting technique allows successful intraspecific differentiation. The present study confirmed the presence of exopolysaccharide-producing strain of P. pentosaceus in indigenous fermented foods which could be used as autochthonous starter culture to impart more functional attributes to fermented foods.

Growth Dynamics of Bacterial Populations in a Two-Compartment Biofilm Bioreactor Designed for Continuous Surfactin Biosynthesis.

Biofilm bioreactors are promising systems for continuous biosurfactant production since they provide process stability through cell immobilization and avoid foam formation. In this work, a two-compartment biofilm bioreactor was designed consisting of a stirred tank reactor and a trickle-bed reactor containing a structured metal packing for biofilm formation. A strong and poor biofilm forming B. subtilis 168 strain due to restored exopolysaccharides (EPS) production or not were cultivated in the system to study the growth behavior of the planktonic and biofilm population for the establishment of a growth model. A high dilution rate was used in order to promote biofilm formation on the packing and wash out unwanted planktonic cells. Biofilm development kinetics on the packing were assessed through a total organic carbon mass balance. The EPS+ strain showed a significantly improved performance in terms of adhesion capacity and surfactin production. The mean surfactin productivity of the EPS+ strain was about 37% higher during the continuous cultivation compared to the EPS- strain. The substrate consumption together with the planktonic cell and biofilm development were properly predicted by the model (α = 0.05). The results show the efficiency of the biofilm bioreactor for continuous surfactin production using an EPS producing strain.

Isolation and characterization of exopolysaccharide-producing strains of Lactobacillus bulgaricus from curd.

Curd is the most widespread traditional fermented milk product used by a large population and is a good source of vitamin B, protein, and calcium. In this study, the isolation of exopolysaccharide (EPS)‐producing strains of Lactobacillus delbrueckii subsp. bulgaricus from curd samples was carried out. Identification of EPS‐producing strains was done by Gram staining, catalase activity, sugar fermentation test, API 50 CHL, and PCR analysis. These EPS‐producing strains were subjected for the estimation of technological properties such as titratable acidity, curdling time, acidification rate, and texture. The strains best in their technological properties were selected for the production of yogurt in combination with EPS‐ or non‐EPS‐producing strains of Streptococcus thermophilus. The EPS concentration range was from 41 to 268 mg/L in the yogurt. The highest value of EPS concentration was detected in S. thermophilus and non‐EPS‐producing Lb. bulgaricus after 14 days of storage.

Draft Genome Sequence of Lactobacillus fermentum Lf2, an Exopolysaccharide-Producing Strain Isolated from Argentine Cheese.

Lactobacillus fermentum Lf2, an Argentine cheese isolate, can produce high concentrations of exopolysaccharides (EPS). These EPS were shown to improve the texture and rheology of yogurt, as well as to play a protective role in mice exposed to Salmonella enterica serovar Typhimurium. Three gene clusters potentially involved in EPS production were identified in different locations of the L. fermentum Lf2 genome.

Alteromonas pelagimontana sp. nov., a marine exopolysaccharide-producing bacterium isolated from the Southwest Indian Ridge.

A novel exopolysaccharide-producing strain, designated as 5.12T, was isolated from a sediment sample from the Southwest Indian Ridge, Indian Ocean. The strain was Gram-stain-negative, motile, strictly aerobic, and oxidase- and catalase-positive. It grew optimally at 35 °C, at pH 6.0 and in the presence of 3.5 % (w/v) NaCl. Its major isoprenoid quinone was ubiquinone-8 (Q-8) and summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c), C16 : 0 and C18 : 1ω7c were the major cellular fatty acids. The DNA G+C content was 46.1 mol%. 16S rRNA gene sequence analysis suggested that strain 5.12T is a member of the genus Alteromonas. Strain 5.12T exhibited close 16S rRNA gene sequence similarity to Alteromonas lipolytica JW12T (96.1 %), Alteromonas hispanica F-32T (95.9 %), Alteromonas confluentis DSSK2-12T (95.9 %), Alteromonas litorea TF-22T (95.6 %) and Alteromonas mediterranea DET (95.5 %). Strain 5.12T contained phosphatidylethanolamine and phosphatidylglycerol as the major polar lipids. Owing to significant differences in the 16S rRNA gene sequences, as well as the phenotypic and chemotaxonomic characteristics, the novel isolate described here merits classification as a representative of a novel species of the genus Alteromonas, for which the name Alteromonas pelagimontana sp. nov. is proposed. The type strain of this species is 5.12T (LMG 29661T= MCC 3250T).

Characterization of high exopolysaccharide-producing Lactobacillus strains isolated from mustard pickles for potential probiotic applications.

The aim of this study was to characterize high exopolysaccharide (EPS)-producing lactic acid bacteria (LAB) isolated from mustard pickles in Taiwan for potential probiotic applications. Among 39 collected LAB strains, four most productive EPS-producing strains were selected for further analysis. Comparative analyses of 16S rDNA genes rpoA and pheS sequences demonstrated that these strains were members of Lactobacillus plantarum-group (LPG). NCD 2, NLD 4, SLC 13, and NLD 16 showed survival rates of 95.83% ± 0.49%, 95.07% ± 0.64%, 105.84% ± 0.82%, and 99.65% ± 0.31% under simulated gastrointestinal conditions, respectively. No cytotoxic effects on macrophage RAW 264.7 cells were observed when they were treated with a low dose (1 μg/ml) of stimulants extracted from the tested LAB strains. The production of nitric oxide in RAW 264.7 cells incubated with various LAB stimulants showed a dose-dependent increase. Among the four strains, SLC 13 showed higher inhibitory activity on growth of Enterococcus faecalis (BCRC 12302) and Yersinia enterocolitica (BCRC 10807). NLD 4 showed strong inhibitory activity against Escherichia coli O157:H7 (ATCC 43894) as compared with the other three strains. In summary, our results suggest that Lactobacillus pentosus SLC 13 may be a good candidate for probiotic applications and for development of antibacterial compounds. [Int Microbiol 20(2):75-84 (2017)].

Short communication: Presence of Lactococcus and lactococcal exopolysaccharide operons on the leaves of Pinguicula vulgaris supports the traditional source of bacteria present in Scandinavian ropy fermented milk

Some traditional Scandinavian fermented milk products have a pronounced ropy consistency due to the presence of exopolysaccharide-producing strains of Lactococcus lactis ssp. cremoris. Norwegian food folklore describes how leaves from the carnivorous plant Pinguicula vulgaris (common butterwort) may be added to milk to initiate the fermentation of the traditional fermented milk product tettemelk. However, scientific confirmation of the link between the plant and the milk product has not been previously published. In the present study, the microbiome on 20 samples of P. vulgaris leaves collected from 5 different rural geographical locations in Norway and from 4 samples of commercial tettemelk was analyzed using high-throughput sequencing methods. The leaf microbiota of P. vulgaris was dominated by Proteobacteria and Firmicutes and the genus Lactococcus was demonstrated in all leaf samples. In addition, DNA extracted from the leaf microbiome contained genes identical to those responsible for exopolysaccharide production in Lactococcus. These results confirm the traditional use of P. vulgaris as a source of bacteria for the Norwegian ropy fermented milk product tettemelk and indicate that P. vulgaris microbiomes can be a potential source of lactic acid bacteria with interesting dairy technological features.

Enhanced curdlan production with nitrogen feeding during polysaccharide synthesis by Rhizobium radiobacter

Curdlan is a secondary metabolite synthesized by Agrobacterium sp. and some other bacteria. A newly isolated exopolysaccharide-producing strain was identified to be Rhizobium radiobacter CGMCC 12099. The polysaccharide product was confirmed to be curdlan with a molecule weight of 1.4×105Da, and its molecular structure was determined by HPLC and infrared spectrum. Although nitrogen source is necessary for cell reproduction, curdlan production is largely dependent on nitrogen limitation, as well as cell vitality. Here, a nitrogen feeding strategy was investigated to elevate the curdlan production by R. radiobacter. The optimal concentration and addition time of (NH4)2HPO4 were investigated. The results showed that the enhanced cell density was correlated to the amount of (NH4)2HPO4 added. Also, nitrogen addition in earlier fermentation stage was beneficial to the cell growth and curdlan production. Furthermore, continuously feeding strategy was employed by feeding (NH4)2HPO4 at a constant rate of 1.24g/h at 35thh of fermentation for 9h, achieving a final curdlan production of 65.27g/L, productivity of 0.544g/L/h and glucose conversion rate of 38.89%. The curdlan production was improved by 2.1 times compared with that without nitrogen addition. This study provides a feasible and cheap nitrogen feeding strategy to enhance curdlan production.

Draft Genome Sequence of Lactobacillus plantarum SF2A35B.

The lactic acid bacterium Lactobacillus plantarum is intensively studied as a model probiotic species. Here, we present the draft genome sequence of the exopolysaccharide-producing strain SF2A35B.

Cyclic AMP (cAMP) Receptor Protein-cAMP Complex Regulates Heparosan Production in Escherichia coli Strain Nissle 1917.

Heparosan serves as the starting carbon backbone for the chemoenzymatic synthesis of heparin, a widely used clinical anticoagulant drug. The availability of heparosan is a significant concern for the cost-effective synthesis of bioengineered heparin. The carbon source is known as the pivotal factor affecting heparosan production. However, the mechanism by which carbon sources control the biosynthesis of heparosan is unclear. In this study, we found that the biosynthesis of heparosan was influenced by different carbon sources. Glucose inhibits the biosynthesis of heparosan, while the addition of either fructose or mannose increases the yield of heparosan. Further study demonstrated that the cyclic AMP (cAMP)-cAMP receptor protein (CRP) complex binds to the upstream region of the region 3 promoter and stimulates the transcription of the gene cluster for heparosan biosynthesis. Site-directed mutagenesis of the CRP binding site abolished its capability of binding CRP and eliminated the stimulative effect on transcription. (1)H nuclear magnetic resonance (NMR) analysis was further performed to determine the Escherichia coli strain Nissle 1917 (EcN) heparosan structure and quantify extracellular heparosan production. Our results add to the understanding of the regulation of heparosan biosynthesis and may contribute to the study of other exopolysaccharide-producing strains.

A17, the First Sequenced Strain of Lactococcus lactis subsp. cremoris with Potential Immunomodulatory Functions.

Lactococcus lactis subsp. cremoris A17, isolated from Taiwan fermented cabbage, is the first sequenced strain of L. lactis subsp. cremoris with immunomodulatory activity and antiallergic functions. The resulting A17 draft genome contains 2,679,936 bp and indicates that A17 is a potential exopolysaccharide-producing strain without any known virulence gene.

Use of Lactobacillus mucosae DPC 6426, an exopolysaccharide-producing strain, positively influences the techno-functional properties of yoghurt

The performance of exopolysaccharide (EPS)-producing Lactobacillus mucosae DPC 6426 was evaluated as adjunct culture during low-fat yoghurt manufacture. In situ produced EPS during yoghurt manufacture and storage increased to ∼561.09 mg L−1 after 28 days of storage. Performance and viability of the yoghurt cultures (∼109 cfu mL−1) were not influenced by L. mucosae DPC 6426, which maintained a viability of ∼108 cfu mL−1 during storage. A significant decrease (p < 0.05) in syneresis was obtained for yoghurt manufactured with adjunct culture L. mucosae DPC 6426 and viscosity of the EPS-rich yoghurt was significantly higher (p < 0.01) than control yoghurt during storage. Confocal laser scanning microscopy of unstirred yoghurt samples showed that EPS was present in the pores of the gel network.

Effect of an Exopolysaccharide-Producing Strain of Streptococcus Thermophilus on the Yield and Texture of Mexican Manchego-Type Cheese

An exopolysaccharide-producing strain of Streptococcus thermophilus was evaluated in the production of Mexican manchego-type cheese. This ropy strain improved water and fat retention, and significantly increased cheese yield. Furthermore, the ropy strain cheese retained more moisture than control cheese during ripening, suggesting that exopolysaccharide strongly bound water within the protein matrix of the cheese. Scanning electron microscopy confirmed that exopolysaccharide bound to the protein matrix of the cheese, producing a dense network that helped to increase water and fat retention and leading to a more open structure of the cheese that gave a softer product, as confirmed by instrumental texture profile analysis and sensory evaluation. Comparison of scanning electron microscopy micrographs of the different sections of the cheese showed higher concentration of exopolysaccharide in the centre than in the outer sections, indicating that exopolysaccharide production continued during ripening and that the environment at the centre of the cheese (moisture and/or oxygen concentration) favoured exopolysaccharide production. Instrumental texture profile analysis also demonstrated that the ropy strain cheese was more cohesive and less elastic than the control; in contrast, exopolysaccharide did not affect chewiness. The changes in texture could be correlated to composition: hardness increased as water and fat decreased, while springiness decreased with increasing fat. The interactions of exopolysaccharide with the cheese protein matrix had an affect on the increase in cohesiveness of the ropy strain cheese.