Probiotic Bifidobacterium lactis Probio-M8 treated and prevented acute RTI, reduced antibiotic use and hospital stay in hospitalized young children: a randomized, double-blind, placebo-controlled study.

PURPOSE: The development of probiotics has seen tremendous growth over the years, with health benefits ranging from gut health to respiratory. We thus aimed to investigate the effects of probiotic Bifidobacterium lactis Probio-M8 (2 × 1010 log CFU/day) against acute respiratory tract infections (RTI), use of antibiotics, hospitalization period and elucidate the possible mechanisms of action in hospitalized young children. METHOD: A prospective, randomized, double-blind and placebo-controlled study was performed in RTI-hospitalized children. Patients were randomized to either the probiotic (n = 60, mean age 13.81 ± 0.90 months) or placebo (n = 60, mean age 12.11 ± 0.73 months) which were administered upon admission, continued during hospitalization and 4-week post-discharged. RTI and gut health parameters were assessed at these time points using validated questionnaires while concentrations of inflammatory cytokines were assessed via oral swabs. RESULTS: Probio-M8 reduced the duration of nasal, pharyngeal and general flu-like symptoms compared to the placebo during the hospitalization period and 4-week post-discharged (P < 0.05) as compared to the placebo, with a more prevalent effect against lower respiratory tract infections (LRTI). Probio-M8 reduced prescription of antibiotic (P = 0.037), prevented new prescription of antibiotic in non-prescribed patients (P = 0.024) and reduced hospitalization period in antibiotic-prescribed patients (P = 0.004) as compared to the placebo. Oral cytokine levels of TNF-α decreased in the Probio-M8 group (P = 0.001) accompanied by increased in IL-10 (P = 0.018) over 4-week post-discharged, while the placebo group did not exhibit such an effect. Increased IL-10 in the Probio-M8 group was correlated with decreased body ache (r = - 0.296, P = 0.001), headache (r = - 0.295, P = 0.001) and pain during swallow (r = - 0.235, P = 0.010). CONCLUSION: Data from our present study show that B. lactis Probio-M8 could be a potential natural and non-drug strategy for the management of RTI in young children in a safe manner. CLINICAL TRIAL REGISTRATION: Clinical studies (Approval No. USM/JEPeM/19030177) were registered at ClinicalTrials.gov (Identifier No. NCT04122495) on September 30, 2019.

Beneficial features of pediococcus: from starter cultures and inhibitory activities to probiotic benefits.

Pediococci are lactic acid bacteria (LAB) which have been used for centuries in the production of traditional fermented foods. There fermentative abilities were explored by the modern food processing industry in use of pediococci as starter cultures, enabling the production of fermented foods with distinct characteristics. Furthermore, some pediococci strains can produce bacteriocins and other antimicrobial metabolites (AMM), such as pediocins, which are increasingly being explored as bio-preservatives in various food matrices. Due to their versatility and inhibitory spectrum, pediococci bacteriocins and AMM are being extensively researched not only in the food industry, but also in veterinary and human medicine. Some of the pediococci were evaluated as potential probiotics with different beneficial areas of application associated with human and other animals' health. The main taxonomic characteristics of pediococci species are presented here, as well as and their potential roles and applications as starter cultures, as bio-preservatives and as probiotic candidates.

Molecular evolutionary and 3D protein structural analyses of Lactobacillus fermentum elongation factor Tu, a novel brain health promoting factor.

The role of microbiota in gut-brain communication has led to the development of probiotics promoting brain health. Here we report a genomic study of a Lactobacillus fermentum PS150 and its patented bioactive protein, elongation factor Tu (EF-Tu), which is associated with cognitive improvement in rats. The L. fermentum PS150 circular chromosome is 2,238,401 bp and it consists of 2281 genes. Chromosome comparisons with other L. fermentum strains highlighted a cluster of glycosyltransferases as potential candidate probiotic factors besides EF-Tu. Molecular evolutionary analyses on EF-Tu genes (tuf) in 235 bacteria species revealed one to three copies of the gene per genome. Seven tuf pseudogenes were found and three species only possessed pseudogenes, which is an unprecedented finding. Protein variability analysis of EF-Tu showed five highly variable residues (40 K, 41G, 42 L, 44 K, and 46E) on the protein surface, which warrant further investigation regarding their potential roles as binding sites.

Lactobacillus plantarum DR7 Modulated Bowel Movement and Gut Microbiota Associated with Dopamine and Serotonin Pathways in Stressed Adults.

We have previously reported that the administration of Lactobacillus plantarum DR7 for 12 weeks reduced stress and anxiety in stressed adults as compared to the placebo group, in association with changes along the brain neurotransmitters pathways of serotonin and dopamine-norepinephrine. We now aim to evaluate the effects of DR7 on gut functions, gut microbiota compositional changes, and determine the correlations between microbiota changes and the pathways of brain neurotransmitters. The administration of DR7 prevented an increase of defecation frequency over 12 weeks as compared to the placebo (p = 0.044), modulating the increase of stress-induced bowel movement. Over 12 weeks, alpha diversity of gut microbiota was higher in DR7 than the placebo group across class (p = 0.005) and order (p = 0.018) levels, while beta diversity differed between groups at class and order levels (p < 0.001). Differences in specific bacterial groups were identified, showing consistency at different taxonomic levels that survived multiplicity correction, along the phyla of Bacteroides and Firmicutes and along the classes of Deltaproteobacteria and Actinobacteria. Bacteroidetes, Bacteroidia, and Bacteroidales which were reduced in abundance in the placebo group showed opposing correlation with gene expression of dopamine beta hydrolase (DBH, dopamine pathway; p < 0.001), while Bacteroidia and Bacteroidales showed correlation with tryptophan hydroxylase-II (TPH2, serotonin pathway; p = 0.001). A correlation was observed between DBH and Firmicutes (p = 0.002), Clostridia (p < 0.001), Clostridiales (p = 0.001), Blautia (p < 0.001), and Romboutsia (p < 0.001), which were increased in abundance in the placebo group. Blautia was also associated with TDO (p = 0.001), whereas Romboutsia had an opposing correlation with TPH2 (p < 0.001). Deltaproteobacteria and Desulfovibrionales which were decreased in abundance in the placebo group showed opposing correlation with DBH (p = 0.001), whereas Bilophila was associated with TPH2 (p = 0.001). Our present data showed that physiological changes induced by L. plantarum DR7 could be associated with changes in specific taxa of the gut microbiota along the serotonin and dopamine pathways.

Lactobacillus Strains Alleviated Hyperlipidemia and Liver Steatosis in Aging Rats via Activation of AMPK.

In this study, we hypothesized that different strains of Lactobacillus can alleviate hyperlipidemia and liver steatosis via activation of 5' adenosine monophosphate-activated protein kinase (AMPK), an enzyme that is involved in cellular energy homeostasis, in aged rats. Male rats were fed with a high-fat diet (HFD) and injected with D-galactose daily over 12 weeks to induce aging. Treatments included (n = 6) (i) normal diet (ND), (ii) HFD, (iii) HFD-statin (lovastatin 2 mg/kg/day), (iv) HFD-Lactobacillus fermentum DR9 (10 log CFU/day), (v) HFD-Lactobacillus plantarum DR7 (10 log CFU/day), and (vi) HFD-Lactobacillus reuteri 8513d (10 log CFU/day). Rats administered with statin, DR9, and 8513d reduced serum total cholesterol levels after eight weeks (p < 0.05), while the administration of DR7 reduced serum triglycerides level after 12 weeks (p < 0.05) as compared to the HFD control. A more prominent effect was observed from the administration of DR7, where positive effects were observed, ranging from hepatic gene expressions to liver histology as compared to the control (p < 0.05); downregulation of hepatic lipid synthesis and ß-oxidation gene stearoyl-CoA desaturase 1 (SCD1), upregulation of hepatic sterol excretion genes of ATP-binding cassette subfamily G member 5 and 8 (ABCG5 and ABCG8), lesser degree of liver steatosis, and upregulation of hepatic energy metabolisms genes AMPKα1 and AMPKα2. Taken altogether, this study illustrated that the administration of selected Lactobacillus strains led to improved lipid profiles via activation of energy and lipid metabolisms, suggesting the potentials of Lactobacillus as a promising natural intervention for alleviation of cardiovascular and liver diseases.

Lactobacillus sp. improved microbiota and metabolite profiles of aging rats.

Aging is closely associated with altered gut function and composition, in which elderly were reported with reduced gut microbiota diversity and increased incidence of age-related diseases. Probiotics have been shown to exert beneficial health-promoting effects through modulation of intestinal microflora biodiversity, thus the effects of probiotics administration on D-galactose (D-gal) senescence-induced rat were evaluated based on the changes in gut microbiota and metabolomic profiles. Upon senescence induction, the ratio of Firmicutes/ Bacteroidetes was significantly lowered, while treatment with Lactobacillus helveticus OFS 1515 and L. fermentum DR9 increased the ratio at the phylum level (P < 0.05). Study on the genus level showed that L. paracasei OFS 0291 and L. helveticus OFS 1515 administration reduced Bacteroides, which are prominently opportunistic pathogens while L. fermentum DR9 treated rats promoted the proliferation of Lactobacillus compared to the aged rats (P < 0.05). Probiotics treatment did not alter fecal short-chain fatty acid (SCFA) profile, but an increase in acetate was observed in the D-gal rats. The analysis of fecal water-soluble metabolites showed that D-gal induced senescence caused great impact on amino acids metabolism such as urocanic acid, citrulline, cystamine and 5-oxoproline, which could serve as potential aging biomarkers. Treatment with probiotics ameliorated these metabolites in a strain-specific manner, whereby L. fermentum DR9 promoted antioxidative effect through upregulation of oxoproline, whereas both L. paracasei OFS 0291 and L. helveticus OFS 1515 restored the levels of reducing sugars, arabinose and ribose similar to the young rats. D-gal induced senescence did cause significant immunological alteration in the colon of aged rats however, all probiotic strains demonstrated immunomodulatory properties as L. paracasei OFS 0291, L. helveticus OFS 1515 and L. fermentum DR9 alleviated proinflammatory cytokines TNF-α, IFN-γ and IL-1ß as well as IL-4 compared to the aged control (P < 0.05). Our study highlights the potential of probiotics as an anti-aging therapy through healthy gut modulation.

Lactobacillus plantarum DR7 improved upper respiratory tract infections via enhancing immune and inflammatory parameters: A randomized, double-blind, placebo-controlled study.

The aims of this study were to investigate the effects of Lactobacillus plantarum DR7 isolated from bovine milk against upper respiratory tract infections (URTI) and elucidate the possible mechanisms underlying immunomodulatory properties. The DR7 strain (9 log cfu/d) was administered for 12 wk in a randomized, double-blind, and placebo-controlled human study involving 109 adults (DR7, n = 56; placebo, n = 53). Subjects were assessed for health conditions monthly via questionnaires, and blood samples were evaluated for cytokine concentrations, peroxidation and oxidative stress, and gene expression in T cells and natural killer (NK) cells. The administration of DR7 reduced the duration of nasal symptoms (mean difference 5.09 d; 95% CI: 0.42-9.75) and the frequency of URTI (mean difference 0.32; 95% CI: 0.01-0.63) after 12 and 4 wk, respectively, compared with the placebo. The DR7 treatment suppressed plasma proinflammatory cytokines (IFN-γ, TNF-α) in middle-aged adults (30 to 60 yr old), while enhancing anti-inflammatory cytokines (IL-4, IL-10) in young adults (<30 yr old), accompanied by reduced plasma peroxidation and oxidative stress levels compared with the placebo. Young adults who received DR7 showed higher expression of plasma CD44 and CD117 by 4.50- and 2.22-fold, respectively, compared with the placebo. Meanwhile, middle-aged adults showed lower expression of plasma CD4 and CD8 by 11.26- and 1.80-fold, respectively, compared with the placebo, indicating less T-cell activation. In contrast, both young and middle-aged adults who received DR7 showed enhanced presence of nonresting and mature NK cells compared with those who received the placebo. We postulate that DR7 alleviated the symptoms of URTI by improving inflammatory parameters and enhancing immunomodulatory properties.

Floricoccus tropicus gen. nov., sp. nov. and Floricoccus penangensis sp. nov. isolated from fresh flowers of durian tree and hibiscus.

Three strains of Gram-staining-positive, coccus-shaped, lactic acid bacteria, designated as HibF3T, HibF2 and HibF5 were isolated from fresh flowers of hibiscus, and a fourth, DF1T, was isolated from fresh flowers of durian tree, in Penang, Malaysia. Taxonomic characterisation was performed by polyphasic analysis. Sequence similarities of the 16S rRNA gene and the housekeeping rpoA and pheS genes of these strains with their closely-related lactococcal and streptococcal relatives were 92-94, 78 and 81 %, respectively. The results of phylogenetic analysis indicated that strains DF1T, HibF2, HibF5 and HibF3T were clustered together but were clearly separated from species of the genera Streptococcus and Lactococcus, indicating that they represent members of a novel genus of the family Streptococcaceae. Calculation of average nucleotide identity (ANI) values between the genomes of DF1T and HibF3T yielded values of 92.50-92.93 %. ANI values below the cut-off value and distinctive chemotaxonomic characteristics supported the hypothesis that these strains represented two novel species. Major cellular fatty acids in DF1T, HibF2 and HibF5 were C18 : 1ω7c and C16 : 0, while C12 : 0 and C14 : 0 were also dominant, in addition to C18 : 1ω7c and C16 : 0, in HibF3T. A novel genus is proposed with the name Floricoccus gen. nov. which consists of two species, Floricoccus tropicus sp. nov as the type species, and Floricoccus penangensis sp. nov. The respective type strains are DF1T (=LMG 29833T=JCM 31733T) and HibF3T (=LMG 29831T=DSM 31735T).

Physio-chemical, microbiological properties of tempoyak and molecular characterisation of lactic acid bacteria isolated from tempoyak.

This study aims to determine physio-chemical properties of tempoyak, characterise the various indigenous species of lactic acid bacteria (LAB) present at different stages of fermentation and also to determine the survival of selected foodborne pathogens in tempoyak. The predominant microorganisms present in tempoyak were LAB (8.88-10.42 log CFU/g). Fructobacillus durionis and Lactobacillus plantarum were the dominant members of LAB. Other LAB species detected for the first time in tempoyak were a fructophilic strain of Lactobacillus fructivorans, Leuconostoc dextranicum, Lactobacillus collinoides and Lactobacillus paracasei. Heterofermentative Leuconostoc mesenteroides and F. durionis were predominant in the initial stage of fermentation, and as fermentation proceeded, F. durionis remained predominant, but towards the end of fermentation, homofermentative Lb. plantarum became the predominant species. Lactic, acetic and propionic acids were present in concentrations ranging from 0.30 to 9.65, 0.51 to 7.14 and 3.90 to 7.31 mg/g, respectively. Genotyping showed a high degree of diversity among F. durionis and Lb. plantarum isolates, suggesting different sources of LAB. All tested Lb. plantarum and F. durionis (except for one isolate) isolates were multidrug resistant. Salmonella spp., Listeria monocytogenes and Staphylococcus aureus were not detected. However, survival study showed that these pathogens could survive up to 8-12 days. The results aiming at improving the quality and safety of tempoyak.

Probiotics and the BSH-related cholesterol lowering mechanism: a Jekyll and Hyde scenario.

Probiotic microorganisms have been documented over the past two decades to play a role in cholesterol-lowering properties via various clinical trials. Several mechanisms have also been proposed and the ability of these microorganisms to deconjugate bile via production of bile salt hydrolase (BSH) has been widely associated with their cholesterol lowering potentials in prevention of hypercholesterolemia. Deconjugated bile salts are more hydrophobic than their conjugated counterparts, thus are less reabsorbed through the intestines resulting in higher excretion into the feces. Replacement of new bile salts from cholesterol as a precursor subsequently leads to decreased serum cholesterol levels. However, some controversies have risen attributed to the activities of deconjugated bile acids that repress the synthesis of bile acids from cholesterol. Deconjugated bile acids have higher binding affinity towards some orphan nuclear receptors namely the farsenoid X receptor (FXR), leading to a suppressed transcription of the enzyme cholesterol 7-alpha hydroxylase (7AH), which is responsible in bile acid synthesis from cholesterol. This notion was further corroborated by our current docking data, which indicated that deconjugated bile acids have higher propensities to bind with the FXR receptor as compared to conjugated bile acids. Bile acids-activated FXR also induces transcription of the IBABP gene, leading to enhanced recycling of bile acids from the intestine back to the liver, which subsequently reduces the need for new bile formation from cholesterol. Possible detrimental effects due to increased deconjugation of bile salts such as malabsorption of lipids, colon carcinogenesis, gallstones formation and altered gut microbial populations, which contribute to other varying gut diseases, were also included in this review. Our current findings and review substantiate the need to look beyond BSH deconjugation as a single factor/mechanism in strain selection for hypercholesterolemia, and/or as a sole mean to justify a cholesterol-lowering property of probiotic strains.

Constipation anti-aging effects by dairy-based lactic acid bacteria.

Constipation, which refers to difficulties in defecation and infrequent bowel movement in emptying the gastrointestinal system that ultimately produces hardened fecal matters, is a health concern in livestock and aging animals. The present study aimed to evaluate the potential effects of dairy-isolated lactic acid bacteria (LAB) strains to alleviate constipation as an alternative therapeutic intervention for constipation treatment in the aging model. Rats were aged via daily subcutaneous injection of D-galactose (600 mg/body weight [kg]), prior to induction of constipation via oral administration of loperamide hydrochloride (5 mg/body weight [kg]). LAB strains (L. fermentum USM 4189 or L. plantarum USM 4187) were administered daily via oral gavage (1 × 10 Log CFU/day) while the control group received sterile saline. Aged rats as shown with shorter telomere lengths exhibited increased fecal bulk and soften fecal upon administration of LAB strains amid constipation as observed using the Bristol Stool Chart, accompanied by a higher fecal moisture content as compared to the control (p < 0.05). Fecal water-soluble metabolite profiles showed a reduced concentration of threonine upon administration of LAB strains compared to the control (p < 0.05). Histopathological analysis also showed that the administration of LAB strains contributed to a higher colonic goblet cell count as compared to the control (p < 0.05). The present study illustrates the potential of dairy-sourced LAB strains as probiotics to ameliorate the adverse effect of constipation amid aging, and as a potential dietary intervention strategy for dairy foods including yogurt and cheese.

Effect of electroporation on viability and bioconversion of isoflavones in mannitol-soymilk fermented by lactobacilli and bifidobacteria.

BACKGROUND: The aim of this study was to evaluate the effect of electroporation (2.5-7.5 kV cm⁻¹ for 3.0-4.0 ms) on the growth of lactobacilli and bifidobacteria, membrane properties and bioconversion of isoflavones in mannitol-soymilk. RESULTS: The viability of lactobacilli and bifidobacteria decreased immediately after electroporation. This was attributed to lipid peroxidation, which led to alterations in the membrane phospholipid bilayer, specifically at the polar head, interface and apolar tail regions. Such alterations also resulted in decreased membrane fluidity and increased membrane permeability upon electroporation (P < 0.05). However, the effect was reversible and treated cells showed better growth than the control upon fermentation for 24 h at 37 °C (P < 0.05). Additionally, electroporation increased the bioconversion of glucosides to bioactive aglycones in mannitol-soymilk, which was attributed to increased intracellular and extracellular ß-glucosidase activities of cells upon treatment (P < 0.05). CONCLUSION: Application of electroporation on lactobacilli and bifidobacteria could be beneficial for the development of fermented soymilk with enhanced bioactivity. Considering the enhanced bioactive aglycones, this soymilk could be useful for the prevention of hormone-dependent disorders.

Probiotic Improves Skin Oxidation, Elasticity, and Structural Properties in Aging Rats.

Skin aging, which affects all living organisms, is associated with oxidative stress. Probiotics exhibit antioxidant properties by producing reactive metabolites that counter oxidative stress. We hypothesized that Limosilactobacillus fermentum USM 4189 (LF 4189) has antioxidative properties and may prevent skin aging. In the present study, we used a D-galactose senescence-induced rat model to evaluate the potential antioxidative capability of LF 4189. The results indicated that rats administered LF 4189 exhibited increased plasma antioxidative activity (P=0.004), lipid peroxidation capacity (P=0.007), and skin elasticity compared with untreated aged rats (P=0.005). LF 4189 prevented telomere length shortening (P<0.05), indicating the potential to prevent senescence. A higher apoptotic activity was observed in old rats compared with young rats, whereas LF 4189 reduced the expression of four antioxidative enzyme genes that function as radical scavengers (all P<0.05), suggesting that the LF 4189 group had a reduced need to scavenge free radicals. Our findings indicate the potential of probiotics, such as LF 4189, as an anti-aging dietary intervention with antioxidant potential to improve skin health.

Breast milk from healthy women has higher anti-Candida properties than women with vaginal infections during pregnancy.

The aim of this study was to investigate the different immunological and antimicrobial properties of breast milk from women with (W) or without (WO) vaginal yeast infections during pregnancy in 85 lactating women (W, n = 43; WO, n = 42). Concentrations of IL-10, IgA, IgM, IgG, EGF, and TGF-α were similar in both groups. However, breast milk of women aged below 31 years old from the W-group showed higher concentration of EGF than the WO-group (p = 0.031). Breast milk from WO-group exhibited higher anti-Candida properties than W-group, both via growth inhibition and aggregation of yeast cells (p < 0.001). Correlation analysis showed that breast milk concentration of TGF-α positively correlated with concentrations of IL-10 (p = 0.001) and IgA (p = 0.021) in the W-group. Data from our present study shows that although breast milk from women with vaginal infections during pregnancy may not sufficiently hinder Candida growth, other immuno-modulatory bioactives may substitute for such a protective effect.

Vaginal Infections during Pregnancy Increase Breast Milk Microbiome Alpha Diversity and Alter Taxonomic Composition.

We previously reported that breast milk from women with (W) or without (WO) vaginal yeast infection during pregnancy differs in its immunological and antimicrobial properties, especially against pathogenic vaginal Candida sp.. Here, we investigated the differences in microbiota profiles of breast milk from these groups. Seventy-two breast milk samples were collected from lactating mothers (W, n=37; WO, n=35). The DNA of bacteria was extracted from each breast milk sample for microbiota profiling by 16S rRNA gene sequencing. Breast milk from the W-group exhibited higher alpha diversity than that from the WO-group across different taxonomic levels of class (P=0.015), order (P=0.011), family (P=0.020), and genus (P=0.030). Compositional differences between groups as determined via beta diversity showed marginal differences at taxonomic levels of phylum (P=0.087), family (P=0.064), and genus (P=0.067). The W-group showed higher abundances of families Moraxellaceae (P=0.010) and Xanthomonadaceae (P=0.008), and their genera Acinetobacter (P=0.015), Enhydrobacter (P=0.015), and Stenotrophomonas (P=0.007). Meanwhile, the WO-group showed higher abundances of genus Staphylococcus (P=0.046) and species Streptococcus infantis (P=0.025). This study shows that, although breast milk composition is affected by vaginal infection during pregnancy, this may not pose a threat to infant growth and development.

Nanotech: propensity in foods and bioactives.

Nanotechnology is seeing higher propensity in various industries, including food and bioactives. New nanomaterials are constantly being developed from both natural biodegradable polymers of plant and animal origins such as polysaccharides and derivatives, peptides and proteins, lipids and fats, and biocompatible synthetic biopolyester polymers such as polylactic acid (PLA), polyhydroxyalkonoates (PHA), and polycaprolactone (PCL). Applications in food industries include molecular synthesis of new functional food compounds, innovative food packaging, food safety, and security monitoring. The relevance of bioactives includes targeted delivery systems with improved bioavailability using nanostructure vehicles such as association colloids, lipid based nanoencapsulator, nanoemulsions, biopolymeric nanoparticles, nanolaminates, and nanofibers. The extensive use of nanotechnology has led to the need for parallel safety assessment and regulations to protect public health and adverse effects to the environment. This review covers the use of biopolymers in the production of nanomaterials and the propensity of nanotechnology in food and bioactives. The exposure routes of nanoparticles, safety challenges, and measures undertaken to ensure optimal benefits that outweigh detriments are also discussed.

Growth, bioconversion of isoflavones and probiotic properties of parent and subsequent passages of Lactobacillus upon ultraviolet radiation.

The objective of this study was to evaluate the effects of ultraviolet (UV) radiation (UVB; 90 J/m²) on growth, bioconversion of isoflavones and probiotic properties of parent and subsequent passages of L. casei FTDC 2113. UV radiation significantly enhanced (P < 0.05) the growth of parent cells in mannitol-soymilk fermented at 37°C for 24 h. This had led to an enhanced intracellular and extracellular ß-glucosidase activity with a subsequent increase in bioconversion of isoflavones in mannitol-soymilk (P < 0.05). UV radiation also promoted (P < 0.05) the tolerance of parent cells towards acidic condition (pH 2 and 3) and intestinal bile salts (oxgall, taurocholic and cholic acid). In addition, parent treated cells also exhibited better (P < 0.05) adhesion ability to mucin and antimicrobial activity compared to that of the control. All these positive effects of UV radiation were only prevalent in the parent cells without inheritance by first, second and third passage of cells. Although temporary, our results suggested that UV radiation could enhance the bioactive and probiotic potentials of L. casei FTDC 2113, and thus could be applied for the production of probiotic products with enhanced bioactivity.

Enhanced growth and bioconversion of isoflavones in prebiotic-soymilk fermented by UV-treated lactobacilli and bifidobacteria.

The aim of this study was to evaluate the effects of ultraviolet (UV) radiation (ultraviolet A (UVA), ultraviolet B (UVB) and ultraviolet C (UVC) at 30-90 J/m²) on the membrane properties of lactobacilli and bifidobacteria, and their bioconversion of isoflavones in prebiotic-soymilk. UV treatment caused membrane permeabilization and alteration at the acyl chain, polar head and interface region of membrane bilayers via lipid peroxidation. Such alteration subsequently led to decreased (p < 0.05) viability of lactobacilli and bifidobacteria immediately after the treatment. However, the effect was transient where cells treated with UV, particularly UVA, grew better in prebiotic-soymilk than the control upon fermentation at 37°C for 24 h (p < 0.05). In addition, UV treatment also increased (p < 0.05) the intracellular and extracellular ß-glucosidase activity of lactobacilli and bifidobacteria. This was accompanied by an increased (p < 0.05) bioconversion of glucosides to bioactive aglycones in prebiotic-soymilk. Our present study illustrated that treatment of lactobacilli and bifidobacteria with UV could develop a fermented prebiotic-soymilk with enhanced bioactivity.