Microflora structure and functional capacity in Tibetan kefir grains and selenium-enriched Tibetan kefir grains: A metagenomic analysis.

Tibetan kefir grains (TKGs) are a complex protein-lipid-polysaccharide matrix composed of various microorganisms. Microorganisms have the benefit of being effective, secure, and controllable when used for selenium enrichment. In this study, selenium-enriched Tibetan kefir grains (Se-TKGs) were made, and the microbiology composition was analyzed through a metagenomic analysis, to explore the influence of selenium enrichment. The microbial composition of TKGs and Se-TKGs, as well as the probiotic species, quorum sensing system (QS) and functional genes were compared and evaluated. Lactobacillus kefiranofaciens was the most abundant microbial species in both communities. Compared with TKGs, Se-TKGs had a much higher relative abundance of acetic acid bacteria. Lactobacillus helveticus was the most common probiotic species both in TKGs and Se-TKGs. Probiotics with antibacterial and anti-inflammatory properties were more abundant in Se-TKGs. QS analysis revealed that Se-TKGs contained more QS system-associated genes than TKGs. Moreover, Kyoto Encyclopedia of Genes and Genomes analysis revealed that the pathway for human disease ko01501 had the greatest relative abundance in both TKGs and Se-TKGs. Compared with TKGs, Se-TKGs demonstrated a greater relative abundance of different drug resistance-related metabolic pathways. Additionally, linear discriminant analysis effect size was used to examine the biomarkers responsible for the difference between the two groups. In this study, we focused on the microbiological structure of TKGs and Se-TKGs, with the aim of establishing a foundation for a more thorough investigation of Se-TKGs and providing a basis for exploring potential future use.

Evaluating the technological properties of lactic acid bacteria in Wagyu cattle milk.

This paper reveals the technological properties of lactic acid bacteria isolated from raw milk (colostrum and mature milk) of Wagyu cattle raised in Okayama Prefecture, Japan. Isolates were identified based on their physiological and biochemical characteristics as well as 16S rDNA sequence analysis. Streptococcus lutetiensis and Lactobacillus plantarum showed high acid and diacetyl-acetoin production in milk after 24 h of incubation at 40 and 30°C, respectively. These strains are thought to have potential for use as starter cultures and adjunct cultures for fermented dairy products.

Biotransformation of Major Ginsenoside Rb1 to Rd by Dekkera anomala YAE-1 from Mongolian Fermented Milk (Airag).

Dekkera anomala YAE-1 strain separated from "airag" (Mongolian fermented mare's milk) produces ß-glucosidase, which can convert ginsenoside Rb1 from Panax ginseng. Ginseng-derived bioactive components such as ginsenoside Rb1 have various immunological and anticancer activities. Airag was collected from five different mare milk farms located near Ulaanbaatar, Mongolia. YAE-1 strains were isolated from airag to examine the hydrolytic activities of ß-glucosidase on Korean Panax ginseng using an API ZYM kit. Supernatants of selected cultures having ß-glucosidase activity were examined for hydrolysis of the major ginsenoside Rb1 at 40°C, pH 5.0. The YAE-1 strain was found to be nearly identical at 99.9% homology with Dekkera anomala DB-7B, and was thus named Dekkera anomala YAE-1. This strain exerted higher ß-glucosidase activity than other enzymes. Reaction mixtures from Dekkera anomala YAE-1 showed great capacity for converting ginsenoside Rb1 to ginsenoside Rd. The ß-glucosidase produced by Dekkera anomala YAE-1 was able to hydrolyze ginsenoside Rb1 and convert it to Rd during fermentation of the ginseng. The amount of ginsenoside Rd was highly increased from 0 to 1.404 mg/ml in fermented 20% ginseng root at 7 days.

Cancer-protective effect of a synbiotic combination between Lactobacillus gasseri 505 and a Cudrania tricuspidata leaf extract on colitis-associated colorectal cancer.

Previously, a synbiotic combination of probiotic Lactobacillus gasseri 505 (LG) and a new prebiotic, Cudrania tricuspidata leaf extract (CT) in fermented milk, designated FCT, showed an in vitro immunomodulatory effect and antioxidant activity. Although synbiotic combination might have cancer-protective effects, these activities have not been fully validated in vivo. Ten-week treatment of LG, CT, or FCT to azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colitis-associated colorectal cancer (CAC) mouse model reduced both the incidence of colonic tumors and damage to the colonic mucosa effectively, suggesting a cancer-protective effect. To understand these, biomarkers associated with inflammation, colon barrier, apoptosis, and cancer cell proliferation were monitored in AOM/DSS group versus LG/CT/FCT groups. A synbiotic combination (FCT) down-regulated pro-inflammatory cytokines (TNF-α, IFN-γ, IL-1ß, and IL-6) and inflammation-associated enzymes (iNOS and COX-2), and up-regulated anti-inflammatory cytokines (IL-4 and IL-10). In addition, colon barrier experiment revealed that biomarkers of mucus layer (MUC-2 and TFF3) and tight junction (occludin and ZO-1) were up-regulated. Subsequent apoptosis experiment showed that pro-apoptotic factors (p53, p21, and Bax) were up-regulated and anti-apoptotic factors (Bcl-2 and Bcl-xL) were down-regulated. Furthermore, comparative metagenome analysis of gut microbiota revealed that Staphylococcus decreased but Lactobacillus, Bifidobacterium, and Akkermansia increased, supporting their protective effects, accompanied by increased short-chain fatty acids (SCFAs). Taken together, the FCT administration showed cancer-protective effects by reducing the risk of colitis-associated colon cancer via regulation of inflammation, carcinogenesis, and compositional change of gut microbiota. Consequently, the synbiotic combination (FCT) could be a novel potential health-protective natural agent against CAC.

Preliminary study for the stimulation effect of plant-based meals on pure culture Lactobacillus plantarum growth and acidification in milk fermentation.

Fermented dairy products have been recognized as the best carriers for the administration of probiotics. Because one of the potential probiotic strains, Lactobacillus plantarum, has poor proteolytic ability and weak acidifying capacity in milk fermentation, the aim of this study was to preliminarily investigate the stimulation effect of plant-based meals on L. plantarum CCFM8661 growth in milk, and subsequently develop a yogurt or yogurt drinks containing probiotic strain L. plantarum CCFM8661. Milk supplemented with different concentrations (5 to 10%, wt/wt) of oat extract and malt extract, inoculated with 2.5 × 107 cfu/mL of L. plantarum CCFM8661, and then incubated at 35°C. The pH value, titration acidity, and viable cell counts during 48-h fermentation at 35°C and 25-d storage at 4°C, were determined at different intervals. The results showed that the promotion effects of oat extract and malt extract on L. plantarum CCFM8661 growth rate in milk were much stronger than almond, walnut, sweet corn, peanut, and soybean meals. In addition, the stimulation effect of oat extract was associated with its concentration, and was much stronger than that of malt extract. Furthermore, viable counts and titration acidity of yogurt were gradually increased in the oat extract group, whereas viable counts were gradually decreased and titration acidity were slightly increased in the malt extract group during the 25-d storage at 4°C.

Use of Streptococcus thermophilus for the in situ production of γ-aminobutyric acid-enriched fermented milk.

γ-Aminobutyric acid (GABA) is a potentially bioactive ingredient with health-promoting properties that is added to functional foods. Streptococcus thermophilus was selected to produce naturally GABA-enriched fermented milk. This strain can yield a GABA concentration of 2.8 g/L after a 48-h fermentation. In the presence of 1 g/L food-grade casein hydrolysate as a nitrogen source, S. thermophilus yielded GABA concentrations as high as 5.4 g/L or even 8.3 g/L when cocultured with Lactobacillus rhamnosus. In other words, both of these added conditions promoted GABA enrichment. The GABA dose achieved with fermented milk was comparable to the doses of commercially available GABA supplements. Additionally, the in situ use of S. thermophilus to produce GABA-enriched fermented milk was cost effective. The complete genomic sequence of S. thermophilus GABA has been published and will be highly useful to other researchers studying the regulation of genes related to GABA accumulation. In conclusion, the S. thermophilus GABA-producing strain reported herein represents a natural method for the production of fermented milk containing high GABA concentrations.

Impact of Buckwheat Fermented Milk Combined with High-Fat Diet on Rats' Gut Microbiota and Short-Chain Fatty Acids.

The aim of this study was to evaluate the effect of buckwheat fermented milk on intestinal flora and short-chain fatty acids (SCFAs) of rats fed a high-fat diet (HFD). Buckwheat fermented milk was made with Lactobacillus plantarum ST-Ⅲ, Lactobacillus bulgaricus, and Streptococcus thermophilus. Thirty-six males C57BL/6 rats (aged 3 weeks and with 9 to 12 g weight) were subjected to a 2-week adaptive period on a normal diet. After a week of acclimatization, the rats were randomly divided into three groups with 12 rats in each group. The high-fat diet with fermented milk (HFDFM) group received HFD supplemented with fermented milk, and the high-fat diet supplemented with buckwheat fermented milk (HFDBFM) group received HFD plus buckwheat fermented milk. Besides, the gavage dose was 0.4 mL/day. After the feedings, colon levels of cytokines and antioxidant indices of the liver, colon, and duodenum tissues were measured. The composition of intestinal flora of rats and the content of SCFAs were determined by gas chromatography-mass spectrometry and Illumina high-throughput sequencing technology. Supplementation with buckwheat fermented milk significantly inhibited the increases in lipopolysaccharide levels in colon and antioxidant indexes in the HFD-fed rats. In addition, buckwheat fermented milk could significantly enhance Firmicutes and decrease Bacteroidetes compared to HFDFM. In addition, SCFA concentrations in HFDBFM were higher than other groups. In conclusion, buckwheat fermented milk can alleviate the damage of HFD to intestinal flora of rats. It modulates microbiota composition and SCFA concentrations to balance the intestinal environment, which will benefit to rats' intestinal health. PRACTICAL APPLICATION: This study explored the effect of buckwheat fermented milk on the regulation of intestinal microflora and SCFAs in rats fed a high-fat diet. It provides new ideas for the development of buckwheat fermented food.

Identification of bioactive compounds in Lactobacillus paracasei subsp. paracasei NTU 101-fermented reconstituted skimmed milk and their anti-cancer effect in combination with 5-fluorouracil on colorectal cancer cells.

Chemotherapy is currently used to treat colorectal cancer (CRC), the most common cancer worldwide. However, chemotherapeutic drugs are limited by severe side effects or drug resistance. In this study, bioactive compound(s), a mixture of palmitic acid, stearic acid, and glyceryl 1,3-dipalmitate (PSG), in Lactobacillus paracasei subsp. paracasei NTU 101-fermented reconstituted skimmed milk ethanol extract (NTU 101-FMEE) were isolated and identified. PSG (1 : 1.5 : 6.3) at 125 µg mL-1 could significantly decrease CRC cell viability at dosages that were not cytotoxic to healthy colon epithelial cells or macrophages. Moreover, the inhibitory effect of the combination of 62.5 µg mL-1 PSG (1 : 1.5 : 6.3) and 5-fluorouracil (5-FU) was significantly higher than that of 5-FU alone (p < 0.05). PSG up-regulated the activities of apoptosis-related proteins and down-regulated the nuclear factor-κB signaling pathway compared to the levels in the control group. Overall, PSG purified from NTU 101-FMEE possesses the potential to ameliorate CRC by improving the effects of adjuvant chemotherapy drugs and reducing side effects.

Production of γ-aminobutyric acid (GABA) by lactic acid bacteria strains isolated from traditional, starter-free dairy products made of raw milk.

γ-Aminobutyric acid (GABA), an amino acid not used in protein synthesis, intervenes in several physiological functions and has both diuretic and calming effects in humans. Lactic acid bacteria (LAB) strains that produce GABA could be exploited for the manufacture of health-promoting GABA-enriched dairy products. In this study, 262 LAB strains isolated from traditional dairy products made from raw milk without starter cultures were screened for GABA production in culture media supplemented with 1% monosodium glutamate (MSG) using an enzymatic (GABase) method. About half of the strains (123) were found to be GABA producers. Of these, 24, among which were 16 Lactococcus lactis subsp. lactis and three Streptococcus thermophilus strains, produced >1 mM of GABA (range 1.01-2.81 mM) and were selected for further characterisation. GABA production was confirmed in most strains by culturing in 5 mM MSG followed by HPLC quantification. A majority of the strains were confirmed to be GABA producers by this method, although lower production levels were recorded. Using species-specific primers, the gene encoding glutamate decarboxylase (GAD) was PCR-amplified in all but one of the GABA producers analysed. Amplicons sequences were compared to one another and to those held in databases. Except for one Lactobacillus brevis strain, none of the 24 GABA producers investigated produced toxic biogenic amines, such as tyramine, histamine or cadaverine. They were therefore considered safe. Either alone, in mixtures, or in combination with industrial starter or adjunct cultures, these strains might be useful in the development of health-oriented dairy products.

Development of antifungal ingredients for dairy products: From in vitro screening to pilot scale application.

Biopreservation represents a complementary approach to traditional hurdle technologies for reducing microbial contaminants (pathogens and spoilers) in food. In the dairy industry that is concerned by fungal spoilage, biopreservation can also be an alternative to preservatives currently used (e.g. natamycin, potassium sorbate). The aim of this study was to develop antifungal fermentates derived from two dairy substrates using a sequential approach including an in vitro screening followed by an in situ validation. The in vitro screening of the antifungal activity of fermentates derivating from 430 lactic acid bacteria (LAB) (23 species), 70 propionibacteria (4 species) and 198 fungi (87 species) was performed against four major spoilage fungi (Penicillium commune, Mucor racemosus, Galactomyces geotrichum and Yarrowia lipolytica) using a cheese-mimicking model. The most active fermentates were obtained from Lactobacillus brevis, Lactobacillus buchneri, Lactobacillus casei/paracasei and Lactobacillus plantarum among the tested LAB, Propionibacterium jensenii among propionibacteria, and Mucor lanceolatus among the tested fungi. Then, for the 11 most active fermentates, culture conditions were optimized by varying incubation time and temperature in order to enhance their antifungal activity. Finally, the antifungal activity of 3 fermentates of interest obtained from Lactobacillus rhamnosus CIRM-BIA1952, P. jensenii CIRM-BIA1774 and M. lanceolatus UBOCC-A-109193 were evaluated in real dairy products (sour cream and semi-hard cheese) at a pilot-scale using challenge and durability tests. In parallel, the impact of these ingredients on organoleptic properties of the obtained products was also assessed. In semi-hard cheese, application of the selected fermentates on the cheese surface delayed the growth of spoilage molds for up to 21 days, without any effect on organoleptic properties, P. jensenii CIRM-BIA1774 fermentate being the most active. In sour cream, incorporation of the latter fermentate at 2 or 5% yielded a high antifungal activity but was detrimental to the product organoleptic properties. Determination of the concentration limit, compatible with product acceptability, showed that incorporation of this fermentate at 0.4% prevented growth of fungal contaminants in durability tests but had a more limited effect against M. racemosus and P. commune in challenge tests. To our knowledge, this is the first time that the workflow followed in this study, from in vitro screening using dairy matrix to scale-up in cheese and sour cream, is applied for production of natural ingredients relying on a large microbial diversity in terms of species and strains. This approach allowed obtaining several antifungal fermentates which are promising candidates for dairy products biopreservation.

Effects of an ethanol extract from Lactobacillus paracasei subsp. paracasei NTU 101 fermented skimmed milk on lipopolysaccharide-induced periodontal inflammation in rats.

The increased incidence of periodontal disease in recent years has garnered considerable attention. Numerous studies have confirmed that probiotics, such as lactic acid bacteria, can ameliorate periodontal inflammation. The current study aimed to assess the effect of an ethanol extract of Lactobacillus paracasei subsp. paracasei NTU 101-fermented skimmed milk (NTU101FM) on lipopolysaccharide (LPS)-induced periodontal inflammation in rats. NTU101FM ethanol extract significantly ameliorated the weight loss caused by periodontal inflammation. NTU101FM ethanol extract treatment also reduced the oral microbial levels and decreased the levels of alveolar bone loss. Finally, NTU101FM ethanol extract was found to ameliorate periodontal inflammation by decreasing the levels of pro-inflammatory cytokines and reducing oxidative stresses induced by LPS. Overall, our findings demonstrate that NTU101FM ethanol extract could be developed as a functional food that could ameliorate periodontal inflammation.

Impact of multi-functional fermented goat milk beverage on gut microbiota in a dynamic colon model.

The aim of this research was to evaluate the effect of grape probiotic fermented beverages made of goat milk, with or without added grape pomace on gut microbiota in a Simulator of Human Intestinal Microbial Ecosystem (SHIME®). SHIME® model was used to investigate to assess changes in microbial composition and fermentation metabolites (short- and branched-chain fatty acids and ammonium), as well as under the antioxidant capacity. The results demonstrated that the beverages formulated, with or without grape pomace extract, exhibited high dietary fiber, oleic acid, phenolic compounds content and antioxidant activity. Both beverages also kept L. rhamnosus and S. thermophilus viable during their passage through the intestinal tract and had a positive effect on gut microbiota metabolism, increasing the antioxidant capacity and the production of short-chain fatty acids, and decreasing the ammonium concentration. Therefore, the multifunctional beverages formulated in this study can offer a new perspective for the production of foods with positive potential effects on human health.

Short communication: Antioxidative and antibacterial activities on Staphylococcus aureus and Escherichia coli O157:H4 in milk with added ginseng marc extract fermented by Lactobacillus plantarum KCCM 11613P.

Ginseng marc, a by-product of the extraction of fresh ginseng, is known to have bioactive compounds, but is frequently discarded as agriculture waste. The objectives of our study were to assess the antioxidative activity of fermented ginseng marc extract using Lactobacillus plantarum KCCM 11613P and to evaluate antibacterial activity of fermented milk with added ginseng marc extract during fermentation. After 24 h of fermentation of ginseng marc extract, the viable cell number was increased to 7.7 ± 0.1 log cfu/mL, and the pH and total titratable acidity were 4.2 ± 0.4 and 0.6% lactic acid, respectively. The total phenolic and flavonoid contents of fermented ginseng marc extract increased by 32.4 and 23.3%, respectively. Higher antioxidative activity of fermented ginseng marc extract was obtained in the ß-carotene bleaching, ferric-reducing ability of plasma, and ferric thiocyanate assays than the 1,1-diphenyl-2-picrylhydrazy assay. However, the 1,1-diphenyl-2-picrylhydrazy scavenging effect decreased due to lowered pH. During production of fermented milk with ginseng, inhibition rate of Staphylococcus aureus and Escherichia coli were 9.7 and 2.3%, respectively. The present study shows the possibilities of Lactobacillus plantarum KCCM 11613P used as a fermentation strain and ginseng marc used as a functional supplement in milk.

Specific Signatures of the Gut Microbiota and Increased Levels of Butyrate in Children Treated with Fermented Cow's Milk Containing Heat-Killed Lactobacillus paracasei CBA L74.

We recently demonstrated that cow's milk fermented with the probiotic Lactobacillus paracasei CBA L74 (FM-CBAL74) reduces the incidence of respiratory and gastrointestinal tract infections in young children attending school. This effect apparently derives from a complex regulation of non-immune and immune protective mechanisms. We investigated whether FM-CBAL74 could regulate gut microbiota composition and butyrate production. We randomly selected 20 healthy children (12 to 48 months) from the previous randomized controlled trial, before (t0) and after 3 months (t3) of dietary treatment with FM-CBAL74 (FM) or placebo (PL). Fecal microbiota was profiled using 16S rRNA gene amplicon sequencing, and the fecal butyrate concentration was also measured. Microbial alpha and beta diversities were not significantly different between groups prior to treatment. FM-CBAL74 but not PL treatment increased the relative abundance of Lactobacillus Individual Blautia, Roseburia, and Faecalibacterium oligotypes were associated with FM-CBAL74 treatment and demonstrated correlative associations with immune biomarkers. Accordingly, PICRUSt analysis predicted an increase in the proportion of genes involved in butyrate production pathways, consistent with an increase in fecal butyrate observed only in the FM group. Dietary supplementation with FM-CBAL74 induces specific signatures in gut microbiota composition and stimulates butyrate production. These effects are associated with changes in innate and acquired immunity.IMPORTANCE The use of a fermented milk product containing the heat-killed probiotic strain Lactobacillus paracasei CBAL74 induces changes in the gut microbiota, promoting the development of butyrate producers. These changes in the gut microbiota composition correlate with increased levels of innate and acquired immunity biomarkers.

Changes in Adiposity and Body Composition during Anemia Recovery with Goat or Cow Fermented Milks.

To date, no studies are available about adipose tissue modifications during anemia recovery; therefore, the aim of this study is to provide detailed information about adipose tissue homeostasis during anemia recovery with fermented milks. Forty male Wistar rats were placed on a pre-experimental period of 40 days, divided in two groups (normal-Fe diet and Fe-deficient diet). Then rats were fed fermented goat or cow milk-based diets with normal-Fe content during 30 days. Ghrelin and adiponectin decreased in both groups of animals fed fermented goat milk, whereas leptin and NEFA increased. UCP-1 decreased in anemic rats fed either fermented milk, and irisin greatly increased in both groups of animals fed fermented goat milk. Fermented goat milk reduces adiposity, inducing leptin elevation and ghrelin reduction. Conversely, plasma adiponectin concentrations decreased in animals fed fermented goat milk, showing an inverse correlation with NEFA, an important marker of lipid mobilization, indicating increased lipolysis. Irisin up-regulation in animals fed fermented goat milk contributes to a favorable metabolic profile and the browning of adipose tissue during anemia recovery.

Insights into the microbial diversity and community dynamics of Chinese traditional fermented foods from using high-throughput sequencing approaches.

Chinese traditional fermented foods have a very long history dating back thousands of years and have become an indispensable part of Chinese dietary culture. A plethora of research has been conducted to unravel the composition and dynamics of microbial consortia associated with Chinese traditional fermented foods using culture-dependent as well as culture-independent methods, like different high-throughput sequencing (HTS) techniques. These HTS techniques enable us to understand the relationship between a food product and its microbes to a greater extent than ever before. Considering the importance of Chinese traditional fermented products, the objective of this paper is to review the diversity and dynamics of microbiota in Chinese traditional fermented foods revealed by HTS approaches.

Lactic acid fermentation as a tool for increasing the folate content of foods.

Folate is an essential micronutrient involved in numerous vital biological reactions. The dietary consumption of naturally occurring vitamin B9 is often inadequate in many countries, and supplementation or fortification programs (using synthetic folic acid) are implemented to alleviate folate deficiency. Other food-based alternatives are possible, such as the use of lactic acid bacteria (LAB) to synthesize folate during fermentation. Many studies have been conducted on this topic, and promising results were reported for some fermented dairy products. However, in other studies, folate consumption by LAB or rather low folate production were observed, resulting in fermented foods that may not significantly contribute to the recommended B9 intake. In addition, the optimum conditions for folate biosynthesis by LAB are still not clear. The aim of this review was thus to (i) clarify the ability of LAB to produce folate in food products, (ii) check if the production of folate by LAB in various fermented foods is sufficient to meet human vitamin B9 requirements and (iii) suggest ways to optimize folate production by LAB in fermented food products.

Lactobacillus rhamnosus NCDC17 ameliorates type-2 diabetes by improving gut function, oxidative stress and inflammation in high-fat-diet fed and streptozotocintreated rats.

Restoration of dysbiosed gut microbiota through probiotic may have profound effect on type 2 diabetes. In the present study, rats were fed high fat diet (HFD) for 3 weeks and injected with low dose streptozotocin to induce type 2 diabetes. Diabetic rats were then fed Lactobacillus rhamnosus NCDC 17 and L. rhamnosus GG with HFD for six weeks. L. rhamnosus NCDC 17 improved oral glucose tolerance test, biochemical parameters (fasting blood glucose, plasma insulin, glycosylated haemoglobin, free fatty acids, triglycerides, total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol), oxidative stress (thiobarbituric acid reactive substance and activities of catalase, superoxide dismutase and glutathione peroxidase in blood and liver), bifidobacteria and lactobacilli in cecum, expression of glucagon like peptide-1 producing genes in cecum, and adiponection in epididymal fat, while decreased propionate proportions (%) in caecum, and expression of tumour necrosis factor-α and interlukin-6 in epididymal fat of diabetic rats as compared to diabetes control group. These findings offered a base for the use of L. rhamnosus NCDC 17 for the improvement and early treatment of type 2 diabetes.

Bio-transformation of selenium in Se-enriched bacterial strains of Lactobacillus casei.

BACKGROUND: Selenium is an element of very great importance for the proper functioning of the human body, mainly due to its antioxidant properties. Selenium exhibits a preventive effect in the case of cardiovascular disease, the immune system, male infertility and inhibits the toxic action of other agents. Selenium is important for Hashimoto's disease. Intake of selenium in the diet slows the aging process. The biological and toxicological effects of selenium strongly depend on its chemical form. Some organisms for example: plant, yeast, are capable of metabolizing low bioavailable selenium compounds (inorganic selenium) into its high bioavailable forms (organic selenium). OBJECTIVE: The aim of this study was to investigate the bio-transformation of selenium by Lactobacillus bacteria towards the characterisation of selenium metabolites. MATERIAL AND METHODS: The speciation of selenium was evaluated by high performance liquid chromatography with inductively coupled plasma mass spectrometry detector. The extraction of selenium species from lyophilized bacteria was executed with water, the mixture of lipase and protease, as well as lisozyme and sodium dodecyl sulphate. RESULTS: All investigated bacteria strains cultivated in the presence of Na2SeO3 effectively uptake selenium. Surprisingly, none of the applied extraction media exhibited a strong power to release the majority of the uptaken selenium compounds. Thus a maximum of 10% of the selenium was extracted from bacteria exposed to the enzymes. However, it was found that Lactobacillus bacteria are able to metabolize inorganic ions of selenium (IV) into Se-methionine, Se-methyloselenocysteine and other unidentified forms. CONCLUSIONS: The study confirmed the ability of probiotic bacteria to biotransform inorganic selenium into its organic derivatives. Therefore, Se-enriched bacteria can be considered as an addition to the functional food. KEY WORDS: selenium speciation, extraction procedure, Lactobacillus casei bacteria, Lactic acid bacteria (LAB), HPLC ICP-MS, functional food.

Study on the Influence of Tea Extract on Probiotics in Skim Milk: From Probiotics Propagation to Metabolite.

In this study, the influence of tea extract (TE) on the growth of probiotics in skim milk was examined. Lactobacillus plantarum ST-III, Bifidobacterium bifidum Bb02, Lactobacillus acidophilus NCFM, and Lactobacillus rhamnosus GG were used in this study. The introduction of TE in milk significantly stimulated the propagation and acidification of L. rhamnosus GG and L. acidophilus NCFM. The antioxidant capacities and the total free amino acid contents of all fermented milk products were enhanced by the addition of TE; however, there were different antioxidant properties and free amino acid contents of fermented milk samples fermented by different bacteria. With a 9% (w/w) level, the fermentation with L. rhamnosus GG and L. acidophilus NCFM showed larger numbers of viable cells and faster acidifying rates, as well as excellent antioxidant capacity and abundant free amino acids.  The stimulative effects of TE on probiotics can be considered for industrial purposes and has practical implications for commercial applications.