Effects of Lactic Acid Bacteria-Fermented Soymilk on Isoflavone Metabolites and Short-Chain Fatty Acids Excretion and Their Modulating Effects on Gut Microbiota

Lactobacillus rhamnosus strain ASCC 1520 with high soy isoflavone transformation ability was used to ferment soymilk and added to the diet of mice. The impact of L. rhamnosus fermentation on soy isoflavone metabolites and intestinal bacterial community, in conjunction with fecal enzyme activity and short-chain fatty acids (SCFA) excretion was evaluated. Antibiotics intervention resulted in a decrease in fecal enzyme activities and SCFA. Although long-term intake of soymilk or L. rhamnosus-fermented soymilk did not affect the fecal β-glucuronidase and β-galactosidase activities, it improved the β-glucosidase activity when antibiotics were concomitantly administered. Soymilk or fermented soymilk administration increased the isoflavone metabolites (O-DMA and equol) excreted in urine. Antibiotics decreased the daidzein excretion and its metabolites but showed little effect on glycitein and genistein excretion. Principal coordinates analysis (PCoA) of the 16s rRNA gene sequencing data found a remarkable shift in gut microbiota after soymilk administration and antibiotics treatment. Matastats test of the relative abundance of bacterial taxa revealed Odoribacter (Bacteroidales family), Lactobacillus (Lactobacillales order), and Alistipes (Rikenellaceae family) were enriched in soymilk while bacterial taxa from Bacteroides and Lactobacillus were enriched in L. rhamnosus-fermented soymilk. Furthermore, there was less decrease in bacterial taxa with fermented soymilk group even when antibiotics were concomitantly administered. Overall, this study revealed that the gut microbiota of a healthy host is enough for the whole isoflavone metabolism under normal conditions. Feeding mice with L. rhamnosus-fermented soymilk improved fecal enzyme activity and kept the balance of the gut mirobiota when antibiotics were used. PRACTICAL APPLICATION: Feeding mice with L. rhamnosus-fermented soymilk improved fecal enzyme activity and kept the balance of the gut mirobiota when antibiotics were used.

Modulation of the spleen transcriptome in domestic turkey (Meleagris gallopavo) in response to aflatoxin B1 and probiotics

Poultry are highly susceptible to the immunotoxic effects of the food-borne mycotoxin aflatoxin B1 (AFB1). Exposure impairs cell-mediated and humoral immunity, limits vaccine efficacy, and increases the incidence of costly secondary infections. We investigated the molecular mechanisms of AFB1 immunotoxicity and the ability of a Lactobacillus-based probiotic to protect against aflatoxicosis in the domestic turkey (Meleagris gallopavo). The spleen transcriptome was examined by RNA sequencing (RNA-seq) of 12 individuals representing four treatment groups. Sequences (6.9 Gb) were de novo assembled to produce over 270,000 predicted transcripts and transcript fragments. Differential expression analysis identified 982 transcripts with statistical significance in at least one comparison between treatment groups. Transcripts with known immune functions comprised 27.6 % of significant expression changes in the AFB1-exposed group. Short exposure to AFB1 suppressed innate immune transcripts, especially from antimicrobial genes, but increased the expression of transcripts from E3 ubiquitin-protein ligase CBL-B and multiple interleukin-2 response genes. Up-regulation of transcripts from lymphotactin, granzyme A, and perforin 1 could indicate either increased cytotoxic potential or activation-induced cell death in the spleen during aflatoxicosis. Supplementation with probiotics was found to ameliorate AFB1-induced expression changes for multiple transcripts from antimicrobial and IL-2-response genes. However, probiotics had an overall suppressive effect on immune-related transcripts.

Response of the hepatic transcriptome to aflatoxin B1 in domestic turkey (Meleagris gallopavo)

Dietary exposure to aflatoxin B₁ (AFB₁) is detrimental to avian health and leads to major economic losses for the poultry industry. AFB₁ is especially hepatotoxic in domestic turkeys (Meleagris gallopavo), since these birds are unable to detoxify AFB₁ by glutathione-conjugation. The impacts of AFB₁ on the turkey hepatic transcriptome and the potential protection from pretreatment with a Lactobacillus-based probiotic mixture were investigated through RNA-sequencing. Animals were divided into four treatment groups and RNA was subsequently recovered from liver samples. Four pooled RNA-seq libraries were sequenced to produce over 322 M reads totaling 13.8 Gb of sequence. Approximately 170,000 predicted transcripts were de novo assembled, of which 803 had significant differential expression in at least one pair-wise comparison between treatment groups. Functional analysis linked many of the transcripts significantly affected by AFB₁ exposure to cancer, apoptosis, the cell cycle or lipid regulation. Most notable were transcripts from the genes encoding E3 ubiquitin-protein ligase Mdm2, osteopontin, S-adenosylmethionine synthase isoform type-2, and lipoprotein lipase. Expression was modulated by the probiotics, but treatment did not completely mitigate the effects of AFB₁. Genes identified through transcriptome analysis provide candidates for further study of AFB₁ toxicity and targets for efforts to improve the health of domestic turkeys exposed to AFB₁.

Recent Perspectives on the Relations between Fecal Mutagenicity, Genotoxicity, and Diet

DNA damage is an essential component of the genesis of colonic cancer. Gut microbial products and food components are thought to be principally responsible for the damage that initiates disease progression. Modified Ames tests and Comet assays have been developed for measuring mutagenicity and genotoxicity. Their relevance to oncogenesis remains to be confirmed, as does the relative importance of different mutagenic and genotoxic compounds present in fecal water and the bacteria involved in their metabolism. Dietary intervention studies provide clues to the likely risks of oncogenesis. High-protein diets lead to increases in N-nitroso compounds in fecal water and greater DNA damage as measured by the Comet assay, for example. Other dietary interventions, such as non-digestible carbohydrates and probiotics, may lead to lower fecal genotoxicity. In order to make recommendations to the general public, we must develop a better understanding of how genotoxic compounds are formed in the colon, how accurate the Ames and Comet assays are, and how diet affects genotoxicity.

Establishing an EU-China consortium on traditional Chinese medicine research

Traditional Chinese medicine (TCM) is widely used in the European Union (EU) and attracts intense research interests from European scientists. As an emerging area in Europe, TCM research requires collaboration and coordination of actions. Good Practice in Traditional Chinese Medicine Research in the Post-genomic Era, also known as GP-TCM, is the first ever EU-funded 7th Framework Programme (FP7) coordination action, aiming to inform the best practice and harmonise research on the safety and efficacy of TCM through interdisciplinary exchange of experience and expertise among clinicians and scientists. With its increasingly large pool of expertise across 19 countries including 13 EU member states, Australia, Canada, China, Norway, Thailand and the USA, the consortium provides forums and collaboration platforms on quality control, extraction technology, component analysis, toxicology, pharmacology and regulatory issues of Chinese herbal medicine (CHM), as well as on acupuncture studies, with a particular emphasis on the application of a functional genomics approach. The project officially started in May 2009 and by the time of its conclusion in April 2012 a Europe-based academic society dedicated to TCM research will be founded to carry on the mission of GP-TCM.

Probiotics and gut health: A special focus on liver diseases

Probiotic bacteria have well-established beneficial effects in the management of diarrhoeal diseases. Newer evidence suggests that probiotics have the potential to reduce the risk of developing inflammatory bowel diseases and intestinal bacterial overgrowth after gut surgery. In liver health, the main benefits of probiotics might occur through preventing the production and/or uptake of lipopolysaccharides in the gut, and therefore reducing levels of low-grade inflammation. Specific immune stimulation by probiotics through processes involving dendritic cells might also be beneficial to the host immunological status and help prevent pathogen translocation. Hepatic fat metabolism also seems to be influenced by the presence of commensal bacteria, and potentially by probiotics; although the mechanisms by which probiotic might act on the liver are still unclear. However, this might be of major importance in the future because low-grade inflammation, hepatic fat infiltration, and hepatitis might become more prevalent as a result of high fat intake and the increased prevalence of obesity.

Probiotic supplementation reduces a biomarker for increased risk of liver cancer in young men from Southern China

BACKGROUND

In vitro and in vivo studies suggest that selected strains of probiotic bacteria can form tight complexes with aflatoxin B(1) and other carcinogens.

OBJECTIVE

The aim of the present study was to determine whether administration of probiotic bacteria could block the intestinal absorption of aflatoxin B(1) and thereby lead to reduced urinary excretion of aflatoxin B(1)-N(7)-guanine (AFB-N(7)-guanine), a marker for a biologically effective dose of aflatoxin exposure. Elevated urinary excretion of this aflatoxin-DNA adduct is associated with an increased risk of liver cancer.

DESIGN

Ninety healthy young men from Guangzhou, China, were randomly assigned to 2 groups; one group received a mixture of Lactobacillus rhamnosus LC705 and Propionibacterium freudenreichii subsp. shermanii strains 2 times/d for 5 wk, and the other group received a placebo preparation. The subjects provided 4 urine samples: at baseline, at 3 and 5 wk after starting the supplementation, and at the end of the 5-wk postintervention period.

RESULTS

The percentage of samples with negative AFB-N(7)-guanine values tended to be higher in the probiotic group than in the placebo group during the 5-wk intervention period (odds ratio: 2.63, P = 0.052), and a statistically significant decrease in the concentration of urinary AFB-N(7)-guanine was observed in the probiotic group. The reduction was 36% at week 3 and 55% at week 5. The geometric means for the probiotic and placebo groups were 0.24 and 0.49 ng AFB-N(7)-guanine/mL, respectively, during the intervention period (P = 0.005).

CONCLUSION

A probiotic supplement reduces the biologically effective dose of aflatoxin exposure and may thereby offer an effective dietary approach to decrease the risk of liver cancer.

Removal of common Fusarium toxins in vitro by strains of Lactobacillus and Propionibacterium

This study was conducted to examine the ability of selected strains of Lactobacillus and Propionibacterium to remove common Fusarium toxins, trichothecenes, from liquid media. The trichothecenes studied were deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), nivalenol (NIV), fusarenon (FX), diacetoxyscirpenol (DAS), T-2 toxin (T-2) and HT-2 toxin (HT-2). The Lactobacillus rhamnosus strain GG (LGG), Lactobacillus rhamnosus strain LC-705 (LC-705) and Propionibacterium freudenreichii ssp. shermanii JS (PJS) were incubated in PBS buffer containing 20 microg toxin ml(-1) for 1h at 37 degrees C, and after centrifugation the concentration of the toxins was measured in the supernatant fraction. Both viable and heat-killed forms of LGG and PJS were more efficient than LC-705 in removing the toxins from the liquid media. LGG and PJS removed four of the seven tested toxins (the removal varying from 18 to 93%) and LC-705 two toxins (10-64%). Of the toxins, 3-AcDON was not removed by any of the bacteria; HT-2 was removed by the non-viable LGG and also slightly by non-viable LC-705; DAS was removed by all three bacteria tested. Binding is postulated as the possible mechanism of the removal, since no difference was observed between the ability of viable and heat-killed bacteria in removing the trichothecenes, and no degradation products of the toxins were detected by gas chromatography (GC)-mass spectrometry (MS) analysis. It is concluded that significant differences exist in the ability of the bacteria to bind trichothecenes in vitro.

Surface binding of aflatoxin B(1) by lactic acid bacteria

Specific lactic acid bacterial strains remove toxins from liquid media by physical binding. The stability of the aflatoxin B(1) complexes formed with 12 bacterial strains in both viable and nonviable (heat- or acid-treated) forms was assessed by repetitive aqueous extraction. By the fifth extraction, up to 71% of the total aflatoxin B(1) remained bound. Nonviable bacteria retained the highest amount of aflatoxin B(1). Lactobacillus rhamnosus strain GG (ATCC 53103) and L. rhamnosus strain LC-705 (DSM 7061) removed aflatoxin B(1) from solution most efficiently and were selected for further study. The accessibility of bound aflatoxin B(1) to an antibody in an indirect competitive inhibition enzyme-linked immunosorbent assay suggests that surface components of these bacteria are involved in binding. Further evidence is the recovery of around 90% of the bound aflatoxin from the bacteria by solvent extraction. Autoclaving and sonication did not release any detectable aflatoxin B(1). Variation in temperature (4 to 37 degrees C) and pH (2 to 10) did not have any significant effect on the amount of aflatoxin B(1) released. Binding of aflatoxin B(1) appears to be predominantly extracellular for viable and heat-treated bacteria. Acid treatment may permit intracellular binding. In all cases, binding is of a reversible nature, but the stability of the complexes formed depends on strain, treatment, and environmental conditions.

The effect of orally administered viable probiotic and dairy lactobacilli on mouse lymphocyte proliferation

Four common Lactobacillus strains were screened for their effects on proliferation of mouse splenic lymphocytes. Mice received perorally 10(9) viable bacteria kg(-1) body weight for 7 days. Lactobacillus acidophilus treatment enhanced ex vivo basal proliferation (by 43%) and B-cell response at suboptimal and optimal concentrations of lipopolysaccharide (LPS) (by 27-28%). Conversely, Lactobacillus casei, Lactobacillus gasseri and Lactobacillus rhamnosus inhibited both basal proliferation (by 14-51%) and mitogen-stimulated lymphoproliferation, particularly at supra-optimal concentrations of concanavalin A (by 43-68%) and LPS (by 23-62%). Therefore, these Lactobacillus strains demonstrate strain-specific effects on B- and T-cells and may also alter the splenocyte sensitivity to the cytotoxic effects of mitogens.