The health benefits of probiotics are beyond doubt. The positive effects of lactobacilli and bifidobacteria on the function of many body systems have been repeatedly proven by various studies. To ...completely realize the potential of probiotic microorganisms, the strains should be tested by the greatest combination of characteristics that contribute to the wellness of the host. In this work, for the first time, a combined assessment of the probiotic properties and vitamin B-producing potential of various species and strains of bifidobacteria and lactobacilli was carried out. The presence of an additional advantage, such as vitamin-producing ability, can prevent vitamin deficiency both at the level of the consumption of fermented foods, when the enrichment will occur naturally on the spot, and during colonization by these intestinal strains, when synthesis will occur in vivo. To select potential probiotics, the stress tolerance ability of 16 lactic acid bacteria and bifidobacteria strains to low pH values, bile, and proteolytic enzymes, as well as their ability to autoaggregate, were studied under conditions of modeling the gastrointestinal tract in vitro. The ability of the strains to extracellularly accumulate water-soluble B vitamins was evaluated by capillary electrophoresis. Among the tested strains of bifidobacteria,
VKPM AC-1662 is of interest; it was characterized by the greatest stress tolerance ability and the ability to autoaggregate, in addition to the extracellular synthesis of riboflavin and pyridoxine. Among lactic acid bacteria,
VKPM B-8936 demonstrated the greatest tolerance to low pH,
VKPM B-11007 to duodenal conditions,
VKPM B-2213 to pepsin, and
VKPM B-2214 to pancreatin. The highest percentage of autoaggregation was observed in
VKPM B-2214, which also accumulated the largest amount of pantothenic acid, but it was sensitive to stress conditions. The obtained results could be used to create new products enriched with probiotics and B vitamins.
Lactic acid bacteria (LAB) bacteriocins can be considered as a bio-preservatives and an alternative to antibiotics, but the high manufacturing costs limit their commercial application. The screening ...of LAB strains for bacteriocinogenic activity was carried out and the effect of rye bran enzymatic hydrolysate (RBEH) on gene expression and bacteriocin production was evaluated. qPCR and RT-PCR was applied for bacteriocin gene detection and their expression quantification. The agar diffusion technique with the test strains of Bacillus spp., Staphylococcus spp. and Salmonella enterica was performed for antimicrobial activity assessment of LAB cultivated in MRS broth and RBEH (processed with proteases and cellulases). The genes of different bacteriocins were revealed for thirteen out of eighteen LAB strains, while the antimicrobial activity was detected only for four of them. The strains of Lactobacillus paracasei VKPM B-11657 and L. salivarius VKPM B-2214 with unnamed class IIb bacteriocin gene demonstrated the widest spectrum of activity. The growth patterns and bacteriocin gene expression differed between both strains and media. The activity of cell-free supernatants after cultivation in RBEH was slightly lower. However, the test strain of S. epidermidis was inhibited by L. paracasei cultivated in RBEH but not in MRS. Thus, rye bran can be applied as a sole source of nutrients for LAB fermentation and bacteriocin production.
The diversity and the stability of the microbial community are associated with microecological interactions between its members. Antagonism is one type of interaction, which particularly determines ...the benefits that probiotics bring to host health by suppressing opportunistic pathogens and microbial contaminants in food. Mathematical models allow for quantitatively predicting intrapopulation relationships. The aim of this study was to create predictive models for bacterial contamination outcomes depending on the probiotic antagonism and prebiotic concentration. This should allow an improvement in the screening of synbiotic composition for preventing gut microbial infections. The functional model (fermentation) was based on a three-stage continuous system, and the distal colon section (N
, pH 6.8, flow rate 0.04 h
) was simulated. The strains
ATCC 15703 and
ATCC 9634 were chosen as the model probiotic and pathogen. Oligofructose Orafti P95 (OF) was used as the prebiotic at concentrations of 2, 5, 7, 10, 12, and 15 g/L of the medium. In the first stage, the system was inoculated with
, and a dynamic equilibrium (
count, lactic, and acetic acids) was achieved. Then, the system was contaminated with a 3-day
suspension (spores). The microbial count, as well as the concentration of acids and residual carbohydrates, was measured. A
monoculture was studied as a control. The stationary count of
in monoculture was markedly higher. An increase (up to 8 h) in the lag phase was observed for higher prebiotic concentrations. The specific growth rate in the exponential phase varied at different OF concentrations. Thus, the OF concentration influenced two key events of bacterial infection, which together determine when the maximal pathogen count will be reached. The mathematical models were developed, and their accuracies were acceptable for
(relative errors ranging from 1.00% to 2.58%) and
(relative errors ranging from 0.74% to 2.78%) count prediction.
Synbiotic compositions have a great potential for curing microbial intestinal infections. Novel targeted synbiotics are a promising field of the modern functional food industry. The present research ...assessed the effect of various fructan fractions, initial probiotic counts, and test strains on the antagonistic properties of synbiotics.
The research involved powdered roots of Arctium lappa L. and strains of Bifidobacterium bifidum, Bacillus cereus, and Salmonella enterica. The experiment was based on the central composite rotatable design. A water extract of A. lappa roots was purified and concentrated. Fructan fractions were precipitated at various concentrations of ethanol, dried, and sub jected to carbon-13 nuclear magnetic resonance (13C-NMR) spectrometry. The bifidobacteria and the test strains were co-cultivated in the same medium that contained one of the fractions. Co-cultivation lasted during 10 h under the same conditions. The acid concentrations were determined by high-performance liquid chromatography to define the synbiotic factor.
The obtained fructans were closer to commercial oligofructose in terms of the number and location of NMR peaks. However, they were between oligofructose and inulin in terms of signal intensity. The response surface analysis for bacilli showed that the minimal synbiotic factor value corresponded to the initial probiotic count of 7.69 log(CFU/mL) and the fructan fraction precipitated by 20% ethanol. The metabolites produced by the bacilli also affected their growth. The synbiotic factor response surface for the experiments with Salmonella transformed from parabolic to saddle shape as the initial test strain count increased. The minimal synbiotic factor value corresponded to the lowest precipitant concentration and the highest probiotic count.
The research established a quantitative relationship between the fractional composition of fructans and the antagonistic activity of the synbiotic composition with bifidobacteria. It also revealed how the ratio of probiotic and pathogen counts affects the antagonism. The proposed approach can be extrapolated on other prebiotics and microbial strains in vivo.
The present study is dedicated to the development of novel criteria for assessing the synbiotic effect of prebiotic and probiotic composition against a specific pathogen. These criteria were obtained ...from the quantitative model of
Bifidobacterium adolescentis
ATCC 15703 and
Bacillus cereus
ATCC 9634 (as a model food contaminant) competition in co-culture fermentation. The model is based on the hypothesis that probiotics can reduce the specific growth rate of non-probiotics by producing short-chain fatty acids. To define the relationship between the specific growth rate of non-probiotics and short-chain fatty acid yields, the inhibition constants were determined separately for each inhibitor produced by bifidobacteria (lactic, acetic and propionic acids) in a pure culture of bacilli. Two different equations based on the minimum inhibitor concentration (
MIC
) and inhibition constant (
K
i
) were used to connect the specific growth rate and concentrations of inhibitors. The yields of the inhibitors mentioned above were obtained from co-culture experiments. The experimental values and the values predicted by the model of
Bacillus
count did not differ significantly (R
2
not less than 0.83) in the competition experiments. Therefore, the general criterion of the synbiotic effect was derived from the model and presents the coefficient of non-probiotic specific growth rate reduction as a result of probiotic growth and inhibitor formation in the final co-culture fermentation. This criterion has been examined for different commercial prebiotics coupled with the
Bifidobacterium adolescentis
strain. The synergistic combination of inulin GR with bifidobacteria had the best effect against
Bacillus cereus
ATCC 9634.
Graphical abstract
A number of mechanisms have been proposed explaining probiotics and prebiotics benefit human health, in particular, probiotics have a suppression effect on pathogen growth that can be enhanced with ...the introduction of prebiotics. In vitro models enhanced with computational biology can be useful for selecting a composition with prebiotics from new plant sources with the greatest synergism. Water extracts from burdock root and Jerusalem artichoke tubers were purified by ultrafiltration and activated charcoal and concentrated on a rotary evaporator. Fructans were precipitated with various concentrations of ethanol.
8 VKPM AC-2136 and
ATCC 43300 strains were applied to estimate the synbiotic effect. The growth of bifidobacteria and staphylococci in monocultures and cocultures in broths with glucose, commercial prebiotics, as well as isolated fructans were studied. The minimum inhibitory concentrations (MICs) of lactic and acetic acids for the
strain were determined. A quantitative model joining the formation of organic acids by probiotics as antagonism factors and the MICs of pathogens (as the measure of their inhibition) was tested in cocultures and showed a high predictive value (R
≥ 0.86). The synbiotic factor obtained from the model was calculated based on the experimental data and obtained constants. Fructans precipitated with 20% ethanol and
have the greater synergism against
.
New functional foods produced by fermentation of pretreated with amylolytic and proteolytic enzymes cereal raw materials suspensions by probiotics are presented. Whole meal wheat flour comprising ...organic compounds and microelements was used as source of nutrients. Duozyme (Novozymes) amylases (1% by weight of the substrate) and Protex 40E (Genencor) proteases (2% of the protein content in flour) were applied for hydrolysis. The starter culture was one of the gram-positive probiotic lactic acid bacteria Lactobacillus paracasei (VKPM B-4079), L. rhamnosus (VKPM B-8238), L. plantarum (VKPM B-7583), L. bulgaricus Lb 14 (VKPM B-4626) or L. acidophilus (VKPM B-2105). The count of lactic acid bacteria viable cells was between 8 and 9 log CFU/mL after 12 h of fermentation. The concentration of lactic acid in the fermented product considered as factor of antagonistic activity against pathogenic bacteria was from 5.5 to 10.2 mg/mL. The highest growth (9.00 ± 0.30 log CFU/mL), as well as the highest final concentration of lactic acid (10.2 mg/mL) were observed for L. rhamnosus culture. The final pH values were in the range 3.37-3.68. The count of lactobacilli was not less 7-8 log CFU/mL after the 28 days of refrigerator storage (4 C). Quantitative assessment of fermented beverages organoleptic properties were carried out on 27 volunteers (female and male aged 22 to 60 years). The highest intensity of aroma was observed in the samples fermented with L. rhamnosus and L. paracasei, the samples fermented with L. bulgaricus were the sweetest one. The most acidic samples were obtained with L. plantarum. Interestingly, the products fermented by L. acidophilus, L. plantarum, L. bulgaricus, had similarities in such values as odor, total intensity of aroma, bread aroma, sweetness, and the samples with L. rhamnosus and L. paracasei combined indicators: color, smell, total intensity of aroma, bread aroma, sweetness and bitterness. So cereals enzymatic hydrolysates can compete with dairy products due to the fool chemical composition. The fermented cereal beverages recognized as functional foods in present study have great potential for implementation.
Honey is the unique product which forms in fermentation of flower nectar by bees. It has been known for its healing properties for many centuries. The prevail component of the honey is ...monosaccharides (first of all glucose and fructose). Nevertheless, di-, tri-and oligosaccharides as well as proteins and pigmenting phenolic compounds can be detected. The specific saccharides of honey are in interest as prebiotics. The phenolic compounds can suppress different microbes including pathogens and food contaminants. The four samples of honey the most common in Russia (linden, buckwheat and flower) were studied. Total carbohydrates were not less than 88 % (typically from 95 to 97 %). The proteins were not detected by Kjeldahl method. The greatest content of the total phenolic compounds was found in the buckwheat honey. The test strains of Bifidobacterium adolescentis ATCC 15703 and Bacillus cereus ATCC 9634 (as model food contaminant) were applied for the evaluation of synbiotic effect of honey saccharides. The sterile sample solutions previously standardized by carbohydrates content were supplemented to the fermentation medium as the only carbohydrates source. In addition, the sample solutions preliminary purified from the phenolic compounds were applied. The co-culture fermentations were carried out in anaerobic conditions. The bifidobacteria and bacilli were enumerated as well as lactic and acetic acids concentrations were detected at the beginning and after 10 h. The synbiotic factors were calculated using obtained data as it was described in the earlier studies. The great stimulation of bifidobacteria growth and organic acids production by honey compounds should be pointed. The synbiotic factors for all samples were greater versus glucose and comparable with the commercial fructooligosaccharides. It was defined that the non-purified samples containing the phenolic compounds possess both the stimulation of greater lactic and acetic acids production and stronger bacilli growth suppression.
Prebiotics are one of most common components of functional food. Jerusalem artichoke tubers contain up to 20 % of inulin and oligofructose (OF) well known as probiotic substances. In agriculture ...Jerusalem artichoke (JA) has a number of advantages while it is used. It is zoned in temperate climates like the northern regions of China and Russia. Due to its acceptable organoleptic properties (sweetish taste without bitterness) compared with chicory (commonly used as source of probiotic), JA tubers can be used in functional food directly. On the other hand the term of "prebiotic" is strongly bounded with "probiotic". The products fermented by lactic acid bacteria (LAB) are referred to functional food also. So, three kinds of drink products based on milk whey were studied. The sources of prebiotics were extract of JA tubers (sample 2) and pulp of JA tubers (sample 3), while the control sample 1 didn't containe prebiotics. Two strains of LAB Lactobacillus plantarum and Lactobacillus fermentum were selected for fermentation. The count of Lactobacillus plantarum after fermentation (24 h) was varied from 4.6·10 8 CFU/ml to 7.4·10 8 CFU/ml in different samples, and was maximal in sample 2. Greatest count of Lactobacillus fermentum (2.4·10 8 CFU/ml) was observed in sample 3. The final pH was about 4.0 in all cases. The survival of LAB was studied during 6 weak at 6 °C. Presumably the presence of JA tubers pulp ensured the best stability of Lactobacillus fermentum due to adhesion of LAB cells at solid particles. Final amount of cells decreased at about 20 times (1.2·10 7 CFU/ml) in sample 3, and about 500 times (2.9·10 5 CFU/ml) in sample 1. The suspensions of LAB cells were treated with CTAB (0.02 pg/ml) to confirm their adhesion on JA tubers particles. The variation of LAB count in sample 3 was detected after 3 week of storage. The value mentioned was greater at 2.7 times (3.3·10 7 CFU/ml) in treated suspension. There was not significant difference between treated and not-treated suspensions in samples 1 and 2.
The number of studies aimed at proving the prebiotic properties of certain substances or compositions has been actively increasing, which has led to a large accumulation of scientific information ...that is fragmented and not systematized. Moreover, a number of criteria have been applied in these studies. The lack of an accessible and convenient information space to compare the obtained results seems to hold back not only scientific development, but also practical development in this field. A database called the «On-line Database of Researches on Activity of Prebiotics» (ODRAP) is presented in this article, which contains information about both prebiotics and some probiotics, that were used in these researches. Currently, ODRAP collects 25 bacteria genera or their combinations, 59 bacteria species, 140 prebiotic substances, 61 prebiotic production companies, 2 methods of fermentation, and 271 analyzed articles from 2001 till 2019. To facilitate access to the database, a special Web-interface was created, which allows any user who opens the Web-page to obtain information about the features and activities of prebiotics, as well as to sort the data by species and genus of bacteria applied in tests, the chemical nature or source of prebiotics, and other parameters. The convenience of the Web-interface is that it allows access to the database, regardless of the user platform and from anywhere, via the Internet.
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