Exopolysaccharides production by Lactobacillus acidophilus LA5 and Bifidobacterium animalis subsp. lactis BB12: Optimization of fermentation variables and characterization of structure and bioactivities

Synbiotic yogurt containing konjac mannan oligosaccharides and Bifidobacterium animalis ssp. lactis BB12 alleviates constipation in mice by modulating the stem cell factor (SCF)/c-Kit pathway and gut microbiota

Synbiotic dietary supplements, as an effective means of regulating the gut microbiota, may have a beneficial effect on constipation. This study evaluated the effects of synbiotic yogurt containing konjac mannan oligosaccharides (KMOS) and Bifidobacterium animalis ssp. lactis BB12 (BB12) on constipated Kunming mice (the model group). Following administration of yogurt containing 2.0% KMOS and BB12 (YBK2.0), black fecal weight and number and gastrointestinal transit rate increased by 97.5, 106.3, and 55.7%, respectively, compared with the model group. Serum levels of excitability neurotransmitters (motilin, substance P, and acetylcholine) in the YBK2.0 group were increased by 139.7, 120.4, and 91.8%, respectively, and serum levels of inhibitory neurotransmitters (vasoactive intestinal peptide, nitric oxide, and acetylcholine) were decreased. Moreover, synbiotic yogurt supplementation significantly downregulated the expression of vasoactive intestinal peptide receptor 1 (VIPR1) and upregulated the expression of serotonin receptor 4 (5-HT4) in the colon, and enhanced the expression of the stem cell factor (SCF)/c-Kit pathway. Additionally, YBK2.0 treatment significantly regulated the community composition and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of gut microbiota, which were positively correlated with physiological parameters of constipation. Thus, supplementation with synbiotic yogurt composed of KMOS and BB12 could facilitate fecal excretion by regulating related pathways and the gut microbiota. These findings demonstrated that the synbiotic yogurt can be considered a functional food for alleviating constipation.

Oxidative stress tolerance and antioxidant capacity of lactic acid bacteria as probiotic: a systematic review

Lactic acid bacteria (LAB) are the most frequently used probiotics in fermented foods and beverages and as food supplements for humans or animals, owing to their multiple beneficial features, which appear to be partially associated with their antioxidant properties. LAB can help improve food quality and flavor and prevent numerous disorders caused by oxidation in the host. In this review, we discuss the oxidative stress tolerance, the antioxidant capacity related herewith, and the underlying mechanisms and signaling pathways in probiotic LAB. In addition, we discuss appropriate methods used to evaluate the antioxidant capacity of probiotic LAB. The aim of the present review is to provide an overview of the current state of the research associated with the oxidative stress tolerance and antioxidant capacity of LAB.

Development and Comparative Evaluation of a Novel Fermented Juice Mixture with Probiotic Strains of Lactic Acid Bacteria and Bifidobacteria

As being a rapidly developing area, the production of nondairy-based functional beverages continues to accelerate considerably. In the present study, the probiotification of a mixture of the juices of Jerusalem artichoke, pineapple, pumpkin, spinach, and cucumber has been utilized for the development of probiotic fruit-vegetable juice. Lactic acid fermentation was comparatively performed by Lactobacillus acidophilus DSM13241, Lacticaseibacillus paracasei subsp. paracasei ATCC 55544, Lacticaseibacillus rhamnosus ATCC53103, Lactiplantibacillus plantarum DSMZ 20174, and Bifidobacterium animalis subsp. lactis BB-12 at 37 °C for 24 h. Following, the fermented products were kept at 8 °C for 45 days, and viability of the strains were tested during the storage period, which refers 15th, 30th, and 45th days. During fermentation, the number of viable probiotic cells increased up to 9.42 log CFU/mL. Consequently, at the end of storage, all strains exhibited an acceptable amount of viability along with L. rhamnosus ATCC 53103 with the highest value reaching 9.30 log CFU/mL. The beverage was successfully scaled up in a bioreactor followed by a sensory evaluation. Statistical analysis revealed that there is a significant difference (p < 0.05) on how much the product was enjoyed between all tested samples with an average score of 3.8 out of 7.0. Thus, flavor and consumer acceptability of the beverage was improved with the addition of 30% of apple juice. The results affirm that the proposed novel fermented mixture of Jerusalem artichoke, pineapple, pumpkin, spinach, and cucumber stands as a promising functional product to be placed in the beverage market.

Bio-functional properties of probiotic Lactobacillus: current applications and research perspectives

Lactic acid bacteria as a starter culture are very important component in the fermentation process of dairy and food industry. Application of lactic acid bacteria as probiotic bacteria adds more functionality to the developed product. Gut colonizing bacteria have attractive benefits related to human health. Bio-functional properties such as antimicrobial activity, anti-inflammatory, ACE-inhibitory, antioxidant, antidiarrheal, antiviral, immunomodulatory, hypocholesterolemic, anti-diabetic and anti-cancer activities are the most applicable research areas of lactic acid bacteria. Different strains of Lactobacillus are generally consumed as probiotics and colonize the gastrointestinal tract. Sometimes these bacteria may possess antimicrobial activity and may positively influence the effect of antibiotics. Use of Lactobacillus spp. for the development of functional foods is one of the promising areas of current research and applications. Individual bacterial species have unique biological activity, which may vary from strains to strains and identification of this uniqueness could be helpful in the development of functional and therapeutic food products.

Isolation, purification, characterization and immunostimulatory activity of an exopolysaccharide produced by Lactobacillus pentosus LZ-R-17 isolated from Tibetan kefir

In this study, three strains of lactic acid bacteria isolated from Tibetan kefir grains, including two strains of Lactobacillus pentosus LZ-R-17 and L. helveticus LZ-R-5, and one strain of Lactococcus lactis subsp. lactis LZ-R-12. The ability of three strains to produce exopolysaccharide (EPS) was tested, and L. pentosus LZ-R-17 was found to have the highest EPS yield. One EPS (R-17-EPS) was isolated from the fermented milk by L. pentosus LZ-R-17 and purified by DEAE-52 anion exchange chromatography. Furthermore, R-17-EPS preliminary structure and macrophage immunomodulatory activity in vitro were investigated. On the basis of the analytical results of ultraviolet-visible spectrum, Fourier transform-infrared spectrum, monosaccharide composition analysis and one-dimensional and two-dimensional nuclear magnetic resonance (NMR) spectra, R-17-EPS was found to have an average molecular weight of 1.20 × 106 Da and was composed of galactose and glucose residues with a molar ratio of 1.00:3.15. NMR analysis revealed that the R-17-EPS was a linear hetero-galactoglucan containing repeating units of →2)-α-D-Galp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Glcp-(1→. In addition, R-17-EPS could effectively enhanced the proliferation, phagocytosis, nitric oxide and cytokines production of RAW264.7 cells, suggesting that R-17-EPS had potent immunostimulatory activity and could be explored as immunomodulator in functional food and/or medicine fields.

Statistical optimization of levan: Influence of the parameter on levan structure and angiotensin I-converting enzyme inhibitory

Based on Plackett-Burman design, steepest ascent method, and Box-Behnken design, statistical optimization for B. subtilis AF17 for levan production was carried out. Sucrose, tryptone and initial pH were found to be the most significant parameter (P < 0.05) for levan production. Result showed that the optimum condition was sucrose 162.5 g/L, tryptone 10 g/L, initial pH 7 and maximum yield was 7.9 ± 0.18 g/L in 72 h fermentation. Purified levan was characterized using various physicochemical techniques such as GC-MS, 1H NMR, 13C NMR spectroscopy and SEC/TDA. Based on this data, the structure of levan was independent of initial culture conditions. The biomedical potential of the isolated Bacillus subtilis A17 levan for its angiotensin-I converting enzyme (ACE) inhibition activities was exploited in vitro. Interestingly, levan possessed an important angiotensin I converting enzyme (ACE) inhibitory 81.1 ± 4.1% at 4 mg/mL. The overall, data suggested that levan presents a promising natural source of antihypertensive agents.

Optimization of bacterial cellulose production by Komagataeibacter xylinus PTCC 1734 in a low-cost medium using optimal combined design

This study was aimed to optimize the production of bacterial cellulose (BC) by Komagataeibacter xylinus PTCC 1734 using mixture of date syrup and cheese whey as carbon sources as well as ascorbic acid as a supplementary agent and to characterize the properties of produced BC. The results showed the highest BC production on the 10th day. The 50:50 ratio of date syrup and cheese whey lead to the highest BC production. Three samples were selected in optimal cultivation conditions until the 10th day, with different ascorbic acid concentrations (0, 0.1 and 0.4%). SEM results showed no difference in the morphology of BC product in the optimal samples, where the average diameter of cellulose nanofibers produced was in the range of nanometer. The FTIR test results showed no difference in the chemical structure of cellulose product in different ascorbic acid concentrations. According to XRD and TGA analyses, the highest degree of BC crystallinity and thermal resistance was obtained at maximum ascorbic acid concentration (0.04%). Consequently, the 50:50 ratio of date syrup and cheese whey and 10th day of fermentation time were selected as the best conditions for BC production. Though ascorbic acid reduced production efficiency, it improved the physical properties of the BC product.

Use of bacterial cellulose film modified by polypyrrole/TiO2-Ag nanocomposite for detecting and measuring the growth of pathogenic bacteria

The aim of this study was to use of bacterial cellulose/polypyrrole/TiO₂-Ag (BC/PPy/TiO₂-Ag) nanocomposite film to detect and measure the growth of 5 pathogenic bacteria. For this purpose, at first, 13 BC/PPy/TiO₂-Ag films were fabricated, then bacterial suspensions were prepared according to McFarland standard. The results showed that by increasing the bacterial concentration, the electrical resistance of sensors was decreased and there was a relation between bacterial concentration and bacterial type with electrical resistance change of sensors. The obtained data showed that the sensitivity of the sensors was increased with increasing the concentration of polypyrrole and TiO₂-Ag. FT-IR and SEM tests were performed to investigate the interaction between nanoparticles and determine the size of nanoparticles. The BC/PPy/TiO₂-Ag biosensors are portable and the response time of these sensors is very short for target analysis. Therefore, these sensors have the potential to improve biological safety as diagnostic tools.

Fermentation conditions optimization, purification, and antioxidant activity of exopolysaccharides obtained from the plant growth-promoting endophytic actinobacterium Glutamicibacter halophytocola KLBMP 5180

In this study, an endophytic actinobacterium Glutamicibacter halophytocola KLBMP 5180, was investigated for the production and antioxidant activity of exopolysaccharides (EPSs). First, the suitable fermentation time, temperature, inoculation volume, pH value, and the carbon and nitrogen sources for EPSs production were obtained using the one variable at a time method (OVAT). Then, a central composition design was used for fermentation conditions optimization to obtain the maximum EPS yield. The optimal medium and condition were as follows: 100 mL broth in 250 mL Erlenmeyer flasks, including 3.65 g/L maltose, 9.88 g/L malt extract, 3.40 g/L yeast extract, 1.41 g/L MnCl₂, pH 7.5, culture temperature 28 °C, and 200 rpm for 7 days, which increased the yield of EPSs to 2.89 g/L. Two purified EPSs, 5180EPS-1 (MW 58.9 kDa) and 5180EPS-2 (10.5 kDa), comprising rhamnose, galacturonic acid, glucose, glucuronic acid, xylose, and arabinose, were obtained for chemical analysis and antioxidant evaluation. The scavenging ability and reducing power of the superoxide anion and hydroxyl radicals demonstrated the moderate in vitro antioxidant activities of the two EPSs, thus indicating their potential to be a new source of natural antioxidants. However, further structure elucidation and functional studies need to be continued.

Numerical optimization of probiotic Ayran production based on whey containing transglutaminase and Aloe vera gel

The purpose of this study was to optimize the functional properties of probiotic Ayran. Two-level fractional factorial design with four center points was used to investigate the effect of five independent variables including, reconstructed whey protein (70-90% of milk), salt (0.5-1 g/100 g), Aloe vera gel (0-30 g/100 g), transglutaminase enzyme (0-14 unit/100 g) and storage time (1-21 days). The viability of Lactobacillus acidophilus La-5 and other physicochemical properties such as pH, acidity, viscosity, sedimentation, and color were modeled and then optimized using desirability function method. Results showed that reconstructed whey protein and Aloe vera gel significantly affected the viability of L. acidophilus La-5 and other physicochemical properties (p < 0.05). The viability of L. acidophilus La-5 and viscosity decreased by increasing of whey protein percentage from 70 to 90. Maximum L. acidophilus La-5 count was observed in samples with a minimum level of whey protein and maximum level of Aloe vera gel. Milk replacement with whey protein up to 90% caused to decrease acidity and viscosity significantly but sedimentation increased (p < 0.05). Optimum condition for production of functional Ayran determined as follow: Aloe vera gel concentration: 25.7%, reconstructed whey protein: 70%, salt: 0.58% and transglutaminase enzyme: 5 unit/100 mL.