In vivo Testing of Functional Properties of Three Selected Probiotic Strains

The Application of Probiotic Bacteria from Strawberry (Fragaria ananassa × Duch.) in the Fermentation of Strawberry Tree Fruit (Arbutus unedo L.) Extract

The search for unexplored plant resources that would provide a good basis for the development of novel probiotic functional foods is rapidly increasing. In this context, the strawberry tree fruit (Arbutus unedo L.) is particularly interesting, as it is rich in numerous antioxidant bioactive compounds that have been shown to be beneficial to health, but have not yet found industrial applications. In this work, the probiotic characterization of lactic acid bacteria strain Lactiplantibacillus plantarum DB2, isolated from strawberries (Fragaria ananassa × Duch.), was performed. The tested strain proved to be safe to use, displaying no antibiotic resistance or hemolytic activity. Due to its proven probiotic potential during simulated gastrointestinal transit, its antimicrobial activity, and its coaggregation with pathogens, it was selected for fermentation of an aqueous Arbutus unedo L. extract, which was subsequently microencapsulated and freeze-dried to extend its shelf life and preserve its functional properties. The antioxidant activity of the ferment obtained was maintained (80%), while after microencapsulation and freeze-drying, about 50% and 20% of the antioxidant activity was retained, respectively. In conclusion, this study demonstrates for the first time the application of probiotics isolated from strawberries in the fermentation of strawberry tree extract and monitors the antioxidant activity during post-fermentation formulation, paving the way for a potential industrial application of this underutilized plant.

Autochthonous Enterococcus durans PFMI565 and Lactococcus lactis subsp. lactis BGBU1-4 in Bio-Control of Listeria monocytogenes in Ultrafiltered Cheese

Nowadays, consumers are interested in cheese produced without chemical additives or high-temperature treatments, among which, protective lactic acid bacteria (LAB) cultures could play a major role. In this study, the aims were to isolate, identify and characterize antilisterial LAB from traditionally produced cheese, and utilize suitable LAB in cheese production. Among 200 isolated LAB colonies, isolate PFMI565, with the strongest antilisterial activity, was identified as Enterococcus durans. E. durans PFMI565 was sensitive to clinically important antibiotics (erytromicin, tetracycline, kanamycin, penicillin, vancomycin) and had low acidifying activity in milk. E. durans PFMI565 and the previously isolated bacteriocin producer, Lactococcus lactis subsp. lactis BGBU1–4, were tested for their capability to control Listeria monocytogenes in experimentally contaminated ultrafiltered (UF) cheeses during 35 days of storage at 4 °C. The greatest reductions of L. monocytogenes numbers were achieved in UF cheese made with L. lactis subsp. lactis BGBU1–4 or with the combination of L. lactis subsp. lactis BGBU1–4 and E. durans PFMI565. This study underlines the potential application of E. durans PFMI565 and L. lactis subsp. lactis BGBU1–4 in bio-control of L. monocytogenes in UF cheese.

Innovative Hurdle Technologies for the Preservation of Functional Fruit Juices

Functional nutrition, which includes the consumption of fruit juices, has become the field of interest for those seeking a healthy lifestyle. Functional nutrition is also of great interest to the food industry, with the aims of improving human health and providing economic prosperity in a sustainable manner. The functional food sector is the most profitable part of the food industry, with a fast-growing market resulting from new sociodemographic trends (e.g., longer life expectancy, higher standard of living, better health care), which often includes sustainable concepts of food production. Therefore, the demand for hurdle technology in the food industry is growing, along with the consumption of minimally processed foods, not only because this approach inactivates microorganisms in food, but because it can also prolong the shelf life of food products. To preserve food products such as fruit juices, the hurdle technology approach often uses non-thermal methods as alternatives to pasteurization, which can cause a decrease in the nutritional value and quality of the food. Non-thermal technologies are often combined with different hurdles, such as antimicrobial additives, thermal treatment, and ultraviolet or pulsed light, to achieve synergistic effects and overall quality improvements in (functional) juices. Hence, hurdle technology could be a promising approach for the preservation of fruit juices due to its efficiency and low impact on juice quality and characteristics, although all processing parameters still require optimization.

Synthesis, characterization and application of crosslinked alginate as green packaging material

Plastic films for food wrapping, packing are widely used due to their special properties. These fossil fuel derived films are associated with long degradation time, toxicity and environmental pollution. Pineapple waste, sea weed can be very good renewable, alternative carbon sources to produce edible films. These edible films can be consumed by lower animals thereby overcoming the disposal problems of accumulating waste plastic and hence reducing pollution. In the present study, crosslinked polymers are prepared from pectin (P)/sodium alginate (SA) through crosslinking with bio-based acids such as citric acid (CA) and tartaric acid (TA). Pectin was extracted from waste pineapple shell and sodium alginate extracted from seaweed. The crosslinked films were characterized by using various analytical techniques such as FT-IR, thermogravimetry, and scanning electron microscopy (SEM). Mice feed study (testing of edibility), plant growth substrate and vermicomposting of these films was studied. Finally a suitable application of these newly prepared polymeric films has been evaluated as wrapping material on food products such as chocolate and Indian vegetable puff to enhance the shelf life of food.

Variability in gut mucosal secretory IgA in mice along a working day

Objective

To assess the variability of secretory immunoglobulin A (S-IgA) in the lumen and feces of mice along a working day.

Results

Mice were maintained under a 12 h light–dark cycle, light period starting at 8 AM. S-IgA was determined in feces and intestinal content (after one or three washes) at three points along the day: at the beginning, in the middle and at the end of the light period (ELP). Significant reduction in the content of S-IgA in the small intestine fluid and in feces was observed at the end of the light cycle, which coincides with the end of a regular working day (8 PM) in any given animal facility. It was also observed that three washes of the small intestine were more effective than one flush to recover a significant higher amount of S-IgA, with the smallest coefficient of variation observed by the ELP. A smaller CV would imply a reduced number of animals needed to achieve the same meaningful results. The results may be useful when designing animal trials for the selection of probiotic candidates based on their capacity of activating S-IgA, since it would imply a more rational use of experimental animals.

Lactobacillus plantarum BSGP201683 Isolated from Giant Panda Feces Attenuated Inflammation and Improved Gut Microflora in Mice Challenged with Enterotoxigenic Escherichia coli

In this work, we searched for an effective probiotic that can help control intestinal infection, particularly enterotoxigenic Escherichia coli K88 (ETEC) invasion, in giant panda (Ailuropoda melanoleuca). As a potential probiotic strain, Lactobacillus plantarum BSGP201683 (L. plantarum G83) was isolated from the feces of giant panda and proven beneficial in vitro. This study was aimed to evaluate the protective effect of L. plantarum G83 in mice challenged with ETEC. The mice were orally administered with 0.2 mL of PBS containing L. plantarum G83 at 0 colony-forming units (cfu) mL⁻¹ (control; negative control, ETEC group), 5.0 × 10⁸ cfu mL⁻¹ (LDLP), 5.0 × 10⁹ cfu mL⁻¹ (MDLP), and 5.0 × 10¹⁰ cfu mL⁻¹ (HDLP) for 14 consecutive days. At day 15, the mice (LDLP, MDLP, HDLP, and ETEC groups) were challenged with ETEC and assessed at 0, 24, and 144 h. Animal health status; chemical and biological intestinal barriers; and body weight were measured. Results showed that L. plantarum G83 supplementation protected the mouse gut mainly by attenuating inflammation and improving the gut microflora. Most indices significantly changed at 24 h after challenge compared to those at 0 and 144 h. All treatment groups showed inhibited plasma diamine oxidase activity and _D-lactate concentration. Tight-junction protein expression was down-regulated, and interleukin (IL)-1β, IL-6, IL-8, TLR4, and MyD88 levels were up-regulated in the jejunum in the LDLP and MDLP groups. The number of the Enterobacteriaceae family and the heat-labile enterotoxin (LT) gene decreased (P < 0.05) in the colons in the LDLP and MDLP groups. All data indicated that L. plantarum G83 could attenuate acute intestinal inflammation caused by ETEC infection, and the low and intermediate doses were superior to the high dose. These findings suggested that L. plantarum G83 may serve as a protective probiotic for intestinal disease and merits further investigation.

Proteolytic activity of probiotic strain Lactobacillus helveticus M92

The aim of this research was to investigate the potential of previously defined probiotic strain Lactobacillus helveticus M92 as functional starter culture for fermented dairy products. Therefore, proteolytic activity of L. helveticus M92 was investigated and compared with those of different representatives of probiotic and starter culture strains. Cluster analysis of AFLP fingerprints showed a difference of L. helveticus M92 compared to five other L. helveticus strains, but the percentage of similarity confirmed the identification on species level. Casein hydrolysis by L. helveticus M92 was monitored by agar-well diffusion test, SDS-PAGE and Anson's method. L. helveticus M92 exhibited the highest proteolytic activity among tested probiotic and starter cultures strains with the fastest acidification rate and the highest pH decrease after overnight incubation in skim milk. The presence of prtH2 gene was confirmed by PCR amplification with specific primers, while PCR product was not obtained after amplification with primers specific to prtH. Furthermore, SDS-PAGE LC-MS/MS analysis of insoluble proteome of L. helveticus M92 enabled identification of several proteins involved in proteolytic system of L. helveticus such as protease PrtM as well as proteins involved in Opp peptide transport system and the intracellular peptidases PepE, PepN, and PepQ.

Evaluation of probiotic properties of Lactobacillus plantarum strains isolated from Chinese sauerkraut

Lactobacillus plantarum strains isolated and identified from naturally-fermented Chinese sauerkraut were examined in vitro for potential probiotic properties and in vivo for cholesterol-lowering effect in mice. Among 7 isolated L. plantarum strains, strains S2-5 and S4-1 were found to possess desirable probiotic properties including ability to survive at pH 2.0 for 60 min, tolerate pancreatin and bile salts, adhere to Caco-2 cells, produce high β-galactosidase activity and antimicrobial activity against Escherichia coli O157 and Shigella flexneri CMCC(B). In addition, strains S2-5 and S4-1 were susceptible to several antibiotics, and capable of reducing cholesterol level in MRS medium by assimilation of cholesterol at 20.39 and 22.28 μg ml(-1), respectively. The in vivo study with L. plantarum S4-1 showed that feeding with fermented milk containing this strain was able to effectively reduce serum cholesterol level in mice, demonstrating its potential as an excellent probiotic candidate for applications in functional products.

Improved sauerkraut production with probiotic strain Lactobacillus plantarum L4 and Leuconostoc mesenteroides LMG 7954

Probiotic strain Lactobacillus plantarum L4 and strain Leuconostoc mesenteroides LMG 7954 were applied for the controlled fermentation of cabbage heads. The parameters of the controlled and spontaneous fermentations, including antimicrobial effect of cabbage brines obtained at the end of both fermentations, were monitored. To check out the influence of starter culture strains, 10 randomly chosen lactic acid bacteria, isolated at the end of controlled cabbage heads fermentation were identified by API 50 CHL test, and the presence of the probiotic culture was confirmed by Pulsed Field Gel Electrophoresis. The starter cultures applied for cabbage heads fermentation allowed lowering of NaCl concentrations from 4.0% to 2.5% (w/v), considerably accelerated fermentation process by 14 d, and improved the product quality. The produced sauerkraut heads are considered probiotic product as viable probiotic cells count in final product was higher than 10(6) colony-forming units (CFU) per gram of product.

PRACTICAL APPLICATION

The results of this research could be applied in the production of fermented cabbage heads with added functional (probiotic) value and with lower NaCl concentration with expected shortened fermentation time. This could not only be of economic but also of ecological importance.

Identification and characterization of potential autochthonous starter cultures from a Croatian "brand" product "Slavonski kulen"

The microbial population of a traditional Croatian fermented sausage "Slavonski kulen" was isolated, identified and subjected to technological and functional characterization in order to select potential autochthonous functional starter cultures. Dominant microflora were lactic acid bacteria (LAB), followed by staphylococci. Identification of isolated lactobacilli showed domination of Leuconostoc mesenteroides and Lactobacillus acidophilus while Staphylococcus xylosus and Staphylococcus warneri outnumbered the staphylococcal microbiota. Most of the isolated LAB and Staphylococcus species displayed good growth in the presence of 5% of NaCl and at 12, 18 and 22°C. All LAB and most of the staphylococci possess proteolytic activity and only Staphylococcus xylosus had lipolytic activity. All lactobacilli and staphylococci isolates produced significant concentrations of lactic acid (as determined by HPLC) and showed antimicrobial activity against pathogenic test microorganisms. Dominant LAB and Staphylococcus species displayed growth in the presence of 1% bile. Most of the staphylococci and all of lactobacilli showed sensitivity to all antibiotics tested.

Lactobacillus strain ecology and persistence within broiler chickens fed different diets: identification of persistent strains

Lactobacilli are autochthonous residents in the chicken gastrointestinal tract, where they may potentially be used as probiotics, competitive exclusion agents, or delivery vehicles. The aim of this study was to use an in vivo model to investigate the effect of diet and competing lactic acid bacteria on the colonization of inoculated Lactobacillus strains, with the goal of identifying strains which can consistently colonize or persist for an extended period of several weeks. Chicken-derived Lactobacillus strains were genetically marked with rifampin resistance and administered on day 0 to chickens fed either a normal commercial diet or a specially formulated high-protein diet. Chickens fed the high-protein diet were also coinoculated with two different mixes of additional lactic acid bacteria. Enterobacterial repetitive intergenic consensus sequence-based PCR (ERIC-PCR) was used to identify rifampin-resistant isolates recovered from chickens. Three strains, belonging to the species Lactobacillus agilis, Lactobacillus crispatus, and Lactobacillus vaginalis, were commonly reisolated from the chickens on both diets at days 21 and 42. The ability of these strains to persist was confirmed in a second chicken trial. All three strains persisted throughout the production period in the chickens fed a commercial diet, while only the L. agilis and L. vaginalis strains persisted in the chickens fed the high-protein diet. In both in vivo trials, competing lactic acid bacteria modified representation of the strains recovered, with all three stains capable of competing in the presence of one or both mixes of coinoculated strains. The in vivo model successfully identified three persistent strains that will be characterized further.

Evaluation of adhesion capacity, cell surface traits and immunomodulatory activity of presumptive probiotic Lactobacillus strains

Twelve lactobacilli previously isolated from newborn infants' gastrointestinal tract and Feta cheese were further characterized by pulse field gel eletrophoresis (PFGE). All strains exhibited distinct PFGE genotypic patterns with the exception of DC421 and DC423 strains possessing identical patterns. The strains DC421, 2035 and 2012 were found to posses certain cell surface traits such as hydrophobicity, autoaggregation and/or high adhesive capacity suggesting potential immunomodulatory activity. However, application of the dorsal mouse air pouch system revealed that only the DC421, DC429 and 2035 strains exhibited strong immunostimulatory activity such as increased chemotaxis of polymorphonuclear (PMN) cells in association with increased phagocytosis and cytokine production. The same strains also induced immunomodulatory activity in the gut associated lymphoid tissue in mice in the absence of any inflammatory response. All strains induced IgA production while reduced TNFalpha production by small intestine cells. The strains DC421 and DC429 exerted their effect on the intestine through Toll-like receptor TLR2/TLR4/TLR9 mediated signalling events leading to secretion of a certain profile of cytokines in which gamma interferon (IFN-gamma), interleukin (IL)-5, IL-6 and IL-10 are included. The strain 2035 induced similar cytokine profile through the synergy of TLR2/TLR4. This study further supports the eligibility of the air pouch model to discriminate presumptive probiotic Lactobacillus strains exhibiting immunostimulatory activity in the gut. Furthermore, evidence is provided that the cell surface traits examined may not be the only criteria but an alternative and important component of a complex mechanism that enables a microorganism to interact with the host gut to exert its immunoregulatory activity.

Synbiotic effect of Lactobacillus helveticus M92 and prebiotics on the intestinal microflora and immune system of mice

The synbiotic effect of the oral treatment of Swiss albino mice with milk-based diets supplemented with Lactobacillus helveticus M92 and various kinds of prebiotics was investigated. Survival, competition, adhesion and colonization, as well as, immunomodulating capability of Lb. helveticus M92, in synbiotic combination, in the gastrointestinal tract (GIT) of mice, were monitored. After the mice were fed with synbiotics, the lactic acid bacteria (LAB) counts in faeces were increased and reduction of enterobacteria and sulphite-reducing clostridia was observed. Similar results were obtained in homogenates of small and large intestine of mice on the 1st and 14th day, after feeding with synbiotics. After the mice were orally given viable Lb. helveticus M92 cells, alone or in combination with prebiotic, the concentration of faecal SIgA and total serum IgA antibodies from all immunized mice were higher compared with the control. The specific humoral immune response was not evoked after oral administration, therefore their synbiotic application is suitable. Among inulin, lactulose and raffinose, Lb. helveticus M92 in combination with inulin, has shown the best synbiotic effect on intestinal and faecal microflora and immune system of mice.