Interplay between microbial-derived GABA and host GABA receptor signaling collectively influence the tumorigenic function of GABA in colon cancer.

Although classically recognized as a neurotransmitter, gamma aminobutyric acid (GABA) has also been identified in colonic tumors. Moreover, the gut microbiome represents another potential source of GABA. Both GABAA and GABAB receptors have been implicated in contributing to the effects of GABA in colorectal cancer, with both pro- and anti-tumorigenic functions identified. However, their subunit composition is often overlooked. Studies to date have not addressed whether the GABA-producing potential of the microbiome changes over the course of colon tumor development or whether receptor subunit expression patterns are altered in colon cancer. Therefore, we investigated the clusters of orthologous group frequencies of glutamate decarboxylase (GAD) in feces from two murine models of colon cancer and found that the frequency of microbial GAD was significantly decreased early in the tumorigenic process. We also determined that microbial-derived GABA inhibited proliferation of colon cancer cells in vitro and that this effect of GABA on SW480 cells involved both GABAA and GABAB receptors. GABA also inhibited prostaglandin E2 (PGE2)-induced proliferation and interleukin-6 (IL-6) expression in these cells. Gene expression correlations were assessed using the "Cancer Exploration" suite of the TIMER2.0 web tool and identified that GABA receptor subunits were differentially expressed in human colon cancer. Moreover, GABAA receptor subunits were predominantly positively associated with PGE2 synthase, cyclooxygenase-2 and IL-6. Collectively, these data demonstrate decreased potential of the microbiome to produce GABA during tumorigenesis, a novel anti-tumorigenic pathway for GABA, and that GABA receptor subunit expression adds a further layer of complexity to GABAergic signaling in colon cancer.

Human breastmilk-derived Bifidobacterium longum subsp. infantis CCFM1269 regulates bone formation by the GH/IGF axis through PI3K/AKT pathway.

Bifidobacterium longum subsp. infantis is a prevalent member of the gut microbiota of breastfed infants. In this study, the effects of human breastmilk-derived B.longum subsp. infantis CCFM1269 on bone formation in developing BALB/c mice were investigated. Newborn female and male mice were assigned to control group (administered saline), CCFM11269 group (administered B. longum subsp. infantis CCFM1269, 1 × 109 CFU/mouse/day) and I5TI group (administered B. longum subsp. infantis I5TI, 1 × 109 CFU/mouse/day) from 1-week-old to 3-, 4- and 5-week old. B. longum subsp. infantis I5TI served as a negative control in this study. The results demonstrated that B. longum subsp. infantis CCFM1269 promoted bone formation in growing mice by modulating the composition of the gut microbiota and metabolites. The expression of genes and proteins in the PI3K/AKT pathway was stimulated by B. longum subsp. infantis CCFM1269 through the GH/IGF-1 axis in growing mice. This finding suggests B. longum subsp. infantis CCFM1269 may be useful for modulating bone metabolism during growth.

Altered oral microbiome in Sudanese Toombak smokeless tobacco users carries a newly emerging risk of squamous cell carcinoma development and progression.

There are an estimated 6-10 million smokeless tobacco (Toombak) users in Sudan, the majority being males. Toombak is known to be a carcinogenic product that is likely to modify the oral microbiome spatiality into a high-risk potential for the development and progression of oral cancer, but previous studies are lacking in this field. Here, we endeavour for the first time the exploration of the oral microbiome in key mucosal areas of the oral cavity and assess the microbiome variations in premalignant and oral squamous cell carcinoma (OSCC) samples from both users and non-users of Toombak. 16S rRNA sequencing was performed on DNA obtained from pooled saliva, oral mucosa and supragingival plaque from 78 Sudanese users and non-users of Toombak, aged between 20 and 70 years. In 32 of the pooled saliva samples, the mycobiome (fungal) environment was analysed through ITS sequencing. Then, 46 formalin-fixed paraffin-embedded samples of premalignant and OSCC samples were collected, and their associated microbiomes sequenced. The oral Sudanese microbiome was found to be enriched in Streptococcaceae, but Staphylococcaceae were significantly more abundant amongst Toombak users. Genera enriched in the oral cavity of Toombak users included Corynebacterium_1 and Cardiobacterium while in non-users, Prevotella, Lactobacillus and Bifidobacterium were prominent. Aspergillus was the most abundant fungus in the mouths of Toombak users with a marked loss of Candida. The genus Corynebacterium_1 was abundant in the buccal, floor of the mouth and saliva microbiomes as well as in oral cancer samples from Toombak users indicating a possible role for this genus in the early stages of oral cancer development. An oral cancer microbiome that favours poor survival and metastasis in those who use Toombak also emerged that includes the genera Stenotrophomonas and Schlegelella. Those utilising Toombak carry an altered oral microbiome that may be an additional risk factor for this products carcinogenicity to the oral structures. These significant microbiome modulations are a newly emerging key driving factor in oral cancer development and progression in Toombak users while it is also shown that Toombak users carry an oral cancer microbiome that may increase the potential for a poorer prognosis.

Protocol for a prospective cohort study exploring the gut microbiota of infants with congenital heart disease undergoing cardiopulmonary bypass (the GuMiBear study).

INTRODUCTION: The gut microbiota develops from birth and matures significantly during the first 24 months of life, playing a major role in infant health and development. The composition of the gut microbiota is influenced by several factors including mode of delivery, gestational age, feed type and treatment with antibiotics. Alterations in the pattern of gut microbiota development and composition can be associated with illness and compromised health outcomes.Infants diagnosed with 'congenital heart disease' (CHD) often require surgery involving cardiopulmonary bypass (CPB) early in life. The impact of this type of surgery on the integrity of the gut microbiome is poorly understood. In addition, these infants are at significant risk of developing the potentially devastating intestinal condition necrotising enterocolitis. METHODS AND ANALYSIS: This study will employ a prospective cohort study methodology to investigate the gut microbiota and urine metabolome of infants with CHD undergoing surgery involving CPB. Stool and urine samples, demographic and clinical data will be collected from eligible infants based at the National Centre for Paediatric Cardiac Surgery in Ireland. Shotgun metagenome sequencing will be performed on stool samples and urine metabolomic analysis will identify metabolic biomarkers. The impact of the underlying diagnosis, surgery involving CPB, and the influence of environmental factors will be explored. Data from healthy age-matched infants from the INFANTMET study will serve as a control for this study. ETHICS AND DISSEMINATION: This study has received full ethical approval from the Clinical Research Ethics Committee of Children's Health Ireland, GEN/826/20.

Sudanese Toombak smokeless tobacco users harbour significantly altered long-term cortisol body production.

The Sudanese, in particular its male population, are known to utilise a smokeless tobacco product (Toombak) which is placed in the oral cavity and can be replaced several times a day. Toombak has been shown to harm human health and is highly addictive. The effect on body cortisol response over a retrospective period in users of this product has not been previously explored. In addition, psycho-dependency scores of Toombak users have not been analysed. In this study, 37 male subjects, age 18-45 years were recruited, of which 18 were non-users of Toombak and 19 were Toombak users. One hair sample was collected from each user and non-user of Toombak. Each hair sample (n=37) was placed in a pre-prepared long piece of foil with two labels on either side marked: 'scalp-side' and 'distant-side'. Cortisol was extracted by mincing 10 mg of 'scalp-side' hair, not exceeding 3 cm, with methanol addition, incubation, and sonication. Cortisol was measured using the enzyme-linked immunosorbent assay kit (Enzo Life Sciences, UK). The amount of hair cortisol in the samples was determined using spectrophotometry at wavelength 405 nm measured in pg/ml and visualised with a four parametric logistic curve. Toombak users were further asked to complete the Fagerstrom Test for Nicotine Dependence-Smokeless Tobacco questionnaire (FTND-ST) comprising of six questions. Scores of > 5 indicated a significant dependence, while a score of < 4 marked low to moderate dependence. The mean concentration of hair cortisol in Toombak users (9.7 pg/ml) was significantly lower (p=0.023) compared to non-users (19.4 pg/ml), with total concentrations ranging from 2.1 to 55.6 pg/ml. FTND-ST scores ranged from 4 to 9, with high levels of psycho-dependency (score > 5) and nicotine tolerance found in 85 % of Toombak users. Cortisol body release in Sudanese smokeless tobacco users was found to be significantly altered. While low cortisol levels do lead to anxiolytic effects, in the long-term, this can allow for increased susceptibility to low cortisol-associated diseases.

Dietary-Induced Bacterial Metabolites Reduce Inflammation and Inflammation-Associated Cancer via Vitamin D Pathway.

Environmental factors, including westernised diets and alterations to the gut microbiota, are considered risk factors for inflammatory bowel diseases (IBD). The mechanisms underpinning diet-microbiota-host interactions are poorly understood in IBD. We present evidence that feeding a lard-based high-fat (HF) diet can protect mice from developing DSS-induced acute and chronic colitis and colitis-associated cancer (CAC) by significantly reducing tumour burden/incidence, immune cell infiltration, cytokine profile, and cell proliferation. We show that HF protection was associated with increased gut microbial diversity and a significant reduction in Proteobacteria and an increase in Firmicutes and Clostridium cluster XIVa abundance. Microbial functionality was modulated in terms of signalling fatty acids and bile acids (BA). Faecal secondary BAs were significantly induced to include moieties that can activate the vitamin D receptor (VDR), a nuclear receptor richly represented in the intestine and colon. Indeed, colonic VDR downstream target genes were upregulated in HF-fed mice and in combinatorial lipid-BAs-treated intestinal HT29 epithelial cells. Collectively, our data indicate that HF diet protects against colitis and CAC risk through gut microbiota and BA metabolites modulating vitamin D targeting pathways. Our data highlights the complex relationship between dietary fat-induced alterations of microbiota-host interactions in IBD/CAC pathophysiology.

Exploiting lactic acid bacteria for colorectal cancer: a recent update.

Colorectal cancer (CRC) is the third most common cancer in the world. Currently, chemotherapy and radiotherapy used to treat CRC exhibit many side effects, hence, it is an urgent need to design effective therapies to prevent and treat CRC. Lactic acid bacteria (LAB) can regulate gut microbiota, intestinal immunity, and intestinal mechanical barrier, which is becoming a hot product for the prevention and treatment of CRC, whereas comprehensive reviews of their anti-CRC mechanisms are limited. This review systematically reveals the latest incidence, mortality, risk factors, and molecular mechanisms of CRC, then summarizes the roles of probiotics in alleviating CRC in animal and clinical studies and critically reviews the possible mechanisms by which these interventions exert their activities. It then shows the limitations in mechanisms and clinical studies, and the suggestions for future research are also put forward, which will play an important role in guiding and promoting the basic and clinical research of remising CRC by LAB and the development of LAB products.

Decreased Tissue Omega-6/Omega-3 Fatty Acid Ratio Prevents Chemotherapy-Induced Gastrointestinal Toxicity Associated with Alterations of Gut Microbiome.

Gastrointestinal toxicity (GIT) is a debilitating side effect of Irinotecan (CPT-11) and limits its clinical utility. Gut dysbiosis has been shown to mediate this side effect of CPT-11 by increasing gut bacterial ß-glucuronidase (GUSB) activity and impairing the intestinal mucosal barrier (IMB). We have recently shown the opposing effects of omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFA) on the gut microbiome. We hypothesized that elevated levels of tissue n-3 PUFA with a decreased n-6/n-3 PUFA ratio would reduce CPT-11-induced GIT and associated changes in the gut microbiome. Using a unique transgenic mouse (FAT-1) model combined with dietary supplementation experiments, we demonstrate that an elevated tissue n-3 PUFA status with a decreased n-6/n-3 PUFA ratio significantly reduces CPT-11-induced weight loss, bloody diarrhea, gut pathological changes, and mortality. Gut microbiome analysis by 16S rRNA gene sequencing and QIIME2 revealed that improvements in GIT were associated with the reduction in the CPT-11-induced increase in both GUSB-producing bacteria (e.g., Enterobacteriaceae) and GUSB enzyme activity, decrease in IMB-maintaining bacteria (e.g., Bifidobacterium), IMB dysfunction and systemic endotoxemia. These results uncover a host-microbiome interaction approach to the management of drug-induced gut toxicity. The prevention of CPT-11-induced gut microbiome changes by decreasing the tissue n-6/n-3 PUFA ratio could be a novel strategy to prevent chemotherapy-induced GIT.

Investigating the potential of fish oil as a nutraceutical in an animal model of early life stress.

Background: Early life stress is a key predisposing factor for depression and anxiety disorders. Selective serotonin re-uptake inhibitors (SSRI) are frequently used as the first line of pharmacology treatment for depression but have several negative qualities, i.e. a delay or absence of effectiveness and negative side-effects. Therefore, there is a growing need for new nutraceutical-based strategies to blunt the effects of adverse-life events.Objectives: This study aimed to use the maternal separation model in rats to test the efficacy of fish oil dietary supplementation, on its own and in conjunction with the SSRI anti-depressant fluoxetine, as a treatment for depressive and anxiety-like symptoms associated with early life stress.Methods: Behavioural tests (open field test, elevated plus maze test and forced swim test) and biochemical markers (corticosterone, BDNF, brain fatty acids and short chain fatty acids) were used to analyse the effects of the dietary treatments. Gut microbial communities and relating metabolites (SCFA) were analysed to investigate possible changes in the microbiota-gut-brain axis.Results: Maternally separated rats showed depressive-like behaviours in the forced swim and open field tests. These behaviours were prevented significantly by fluoxetine administration and in part by fish oil supplementation. Associated biochemical changes reported include altered brain fatty acids, significantly lower plasma corticosterone levels (AUC) and reduced brain stem serotonin turnover, compared to untreated, maternally separated (MS) rats. Untreated MS animals had significantly lower ratios of SCFA producers such as Caldicoprobacteraceae, Streptococcaceae, Rothia, Lachnospiraceae_NC2004_group, and Ruminococcus_2, along with significantly reduced levels of total SCFA compared to non-separated animals. Compared to untreated MS animals, animals fed fish oil had significantly higher Bacteroidetes and Prevotellaceae and reduced levels of butyrate, while fluoxetine treatment resulted in significantly higher levels of Neochlamydia, Lachnoclostridium, Acetitomaculum and Stenotrophomonas and, acetate and propionate.Conclusion: Despite the limitations in extrapolating from animal behavioural data and the notable differences in pharmacokinetics between rodents and humans, the results of this study provide a further advancement into the understanding of some of the complex systems within which nutraceuticals and pharmaceuticals effect the microbiota-gut-brain axis.

Disbalance of the Duodenal Epithelial Cell Turnover and Apoptosis Accompanies Insensitivity of Intestinal Redox Homeostasis to Inhibition of the Brain Glucose-Dependent Insulinotropic Polypeptide Receptors in a Rat Model of Sporadic Alzheimer's Disease.

INTRODUCTION: Gastrointestinal dyshomeostasis is investigated in the context of metabolic dysfunction, systemic, and neuroinflammation in Alzheimer's disease. Dysfunctional gastrointestinal redox homeostasis and the brain-gut incretin axis have been reported in the rat model of insulin-resistant brain state-driven neurodegeneration induced by intracerebroventricular streptozotocin (STZ-icv). We aimed to assess whether (i) the structural epithelial changes accompany duodenal oxidative stress; (ii) the brain glucose-dependent insulinotropic polypeptide receptor (GIP-R) regulates redox homeostasis of the duodenum; and (iii) the STZ-icv brain-gut axis is resistant to pharmacological inhibition of the brain GIP-R. METHODS: GIP-R inhibitor [Pro3]-GIP (85 µg/kg) was administered intracerebroventricularly to the control and the STZ-icv rats 1 month after model induction. Thiobarbituric acid reactive substances (TBARSs) were measured in the plasma and duodenum, and the sections were analyzed morphometrically. Caspase-3 expression and activation were assessed by Western blot and multiplex fluorescent signal amplification. RESULTS: Intracerebroventricular [Pro3]-GIP decreased plasma TBARSs in the control and STZ-icv animals and increased duodenal TBARSs in the controls. In the controls, inhibition of brain GIP-R affected duodenal epithelial cells, but not villus structure, while all morphometric parameters were altered in the STZ-icv-treated animals. Morphometric changes in the STZ-icv animals were accompanied by reduced levels of caspase-3. Suppression of brain GIP-R inhibited duodenal caspase-3 activation. CONCLUSION: Brain GIP-R seems to be involved in the regulation of duodenal redox homeostasis and epithelial cell turnover. Resistance of the brain-gut GIP axis and morphological changes indicative of abnormal epithelial cell turnover accompany duodenal oxidative stress in the STZ-icv rats.

Bifidobacterium longum Ameliorates Dextran Sulfate Sodium-Induced Colitis by Producing Conjugated Linoleic Acid, Protecting Intestinal Mechanical Barrier, Restoring Unbalanced Gut Microbiota, and Regulating the Toll-Like Receptor-4/Nuclear Factor-κB Signaling Pathway.

This study aimed to explore the effects and differences of conjugated linoleic acid (CLA)-producing Bifidobacterium longum on the alleviation of dextran sulfate sodium (DSS)-induced colitis and to explore its patterns. Different B. longum strains were administered at 109 cfu/day 7 days before DSS treatment. B. longum CCFM681 significantly increased goblet cells, mucin2 (MUC2), claudin-3, α-catenin1, and ZO-1, but neither B. longum CCFM760 nor B. longum CCFM642 had those protective effects. Interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were downregulated, while IL-10 was upregulated by B. longum CCFM681 but neither by B. longum CCFM760 nor by B. longum CCFM642. Moreover, B. longum CCFM681 treatment inhibited the toll-like receptor-4 (TLR4)/nuclear factor kappa-B (NF-κB) pathway. Furthermore, B. longum CCFM681 treatment rebalanced gut microbiota via regulating the diversity and key microorganisms. Colonic CLA concentrations in mice fed with B. longum CCFM681 were significantly higher than that of DSS-exposed mice, while those in B. longum CCFM760 and B. longum CCFM642 groups showed insignificant difference compared with the DSS group. Moreover, CLA showed a significantly positive correlation with the effectiveness of relieving colitis. B. longum CCFM681 alleviated colitis by protecting the intestinal mechanical barrier, modulating the gut microbiota, and inhibiting the TLR4/NF-κB pathway and associated pro-inflammatory cytokines. These results will help the clinical trials of probiotics and the development of functional products for colitis.

High-fat diet alters stress behavior, inflammatory parameters and gut microbiota in Tg APP mice in a sex-specific manner.

Long-term high-fat diet (HFD) consumption commonly leads to obesity, a major health concern of western societies and a risk factor for Alzheimer's disease (AD). Both conditions present glial activation and inflammation and show sex differences in their incidence, clinical manifestation, and disease course. HFD intake has an important impact on gut microbiota, the bacteria present in the gut, and microbiota dysbiosis is associated with inflammation and certain mental disorders such as anxiety. In this study, we have analyzed the effects of a prolonged (18 weeks, starting at 7 months of age) HFD on male and female mice, both wild type (WT) and TgAPP mice, a model for AD, investigating the behavioral profile, gut microbiota composition and inflammatory/phagocytosis-related gene expression in hippocampus. In the open-field test, no overt differences in motor activity were observed between male and female or WT and TgAPP mice on a low-fat diet (LFD). However, HFD induced anxiety, as judged by decreased motor activity and increased time in the margins in the open-field, and a trend towards increased immobility time in the tail suspension test, with increased defecation. Intriguingly, female TgAPP mice on HFD showed less immobility and defecation compared to female WT mice on HFD. HFD induced dysbiosis of gut microbiota, resulting in reduced microbiota diversity and abundance compared with LFD fed mice, with some significant differences due to sex and little effect of genotype. Gene expression of pro-inflammatory/phagocytic markers in the hippocampus were not different between male and female WT mice, and in TgAPP mice of both sexes, some cytokines (IL-6 and IFNγ) were higher than in WT mice on LFD, more so in female TgAPP (IL-6). HFD induced few alterations in mRNA expression of inflammatory/phagocytosis-related genes in male mice, whether WT (IL-1ß, MHCII), or TgAPP (IL-6). However, in female TgAPP, altered gene expression returned towards control levels following prolonged HFD (IL-6, IL-12ß, TNFα, CD36, IRAK4, PYRY6). In summary, we demonstrate that HFD induces anxiogenic symptoms, marked alterations in gut microbiota, and increased expression of inflammatory genes, except for female TgAPP that appear to be resistant to the diet effects. Lifestyle interventions should be introduced to prevent AD onset or exacerbation by reducing inflammation and its associated symptoms; however, our results suggest that the eventual goal of developing prevention and treatment strategies should take sex into consideration.

Lactobacillus reuteri FYNLJ109L1 Attenuating Metabolic Syndrome in Mice via Gut Microbiota Modulation and Alleviating Inflammation.

Metabolic syndrome is caused by an excessive energy intake in a long-term, high-fat and/or high-sugar diet, resulting in obesity and a series of related complications, which has become a global health concern. Probiotics intervention can regulate the gut microbiota and relieve the systemic and chronic low-grade inflammation, which is an alternative to relieving metabolic syndrome. The aim of this work was to explore the alleviation of two different Lactobacillusreuteri strains on metabolic syndrome. Between the two L. reuteri strains, FYNLJ109L1 had a better improvement effect on blood glucose, blood lipid, liver tissue damage and other related indexes than NCIMB 30242. In particular, FYNLJ109L1 reduced weight gain, food intake and fat accumulation. Additionally, it can regulate the gut microbiota, increase IL-10, and reduce IL-6 and tumor necrosis factor-α (TNF-α), as well as liver injury, and further reduce insulin resistance and regulate lipid metabolism disorders. In addition, it could modulate the gut microbiota, particularly a decreased Romboutsia and Clostridium sensu stricto-1, and an increased Acetatifactor. The results indicated that FYNLJ109L1 could improve metabolic syndrome significantly via alleviating inflammation and gut microbiota modulation.

Pain after upper limb surgery under peripheral nerve block is associated with gut microbiome composition and diversity.

Gut microbiota play a role in certain pain states. Hence, these microbiota also influence somatic pain. We aimed to determine if there was an association between gut microbiota (composition and diversity) and postoperative pain. Patients (n = 20) undergoing surgical fixation of distal radius fracture under axillary brachial plexus block were studied. Gut microbiota diversity and abundance were analysed for association with: (i) a verbal pain rating scale of < 4/10 throughout the first 24 h after surgery (ii) a level of pain deemed "acceptable" by the patient during the first 24 h following surgery (iii) a maximum self-reported pain score during the first 24 h postoperatively and (iv) analgesic consumption during the first postoperative week. Analgesic consumption was inversely correlated with the Shannon index of alpha diversity. There were also significant differences, at the genus level (including Lachnospira), with respect to pain being "not acceptable" at 24 h postoperatively. Porphyromonas was more abundant in the group reporting an acceptable pain level at 24 h. An inverse correlation was noted between abundance of Collinsella and maximum self-reported pain score with movement. We have demonstrated for the first time that postoperative pain is associated with gut microbiota composition and diversity. Further work on the relationship between the gut microbiome and somatic pain may offer new therapeutic targets.

Exploring the Gut Microbiota and Cardiovascular Disease.

Cardiovascular disease (CVD) has been classified as one of the leading causes of morbidity and mortality worldwide. CVD risk factors include smoking, hypertension, dyslipidaemia, obesity, inflammation and diabetes. The gut microbiota can influence human health through multiple interactions and community changes are associated with the development and progression of numerous disease states, including CVD. The gut microbiota are involved in the production of several metabolites, such as short-chain fatty acids (SCFAs), bile acids and trimethylamine-N-oxide (TMAO). These products of microbial metabolism are important modulatory factors and have been associated with an increased risk of CVD. Due to its association with CVD development, the gut microbiota has emerged as a target for therapeutic approaches. In this review, we summarise the current knowledge on the role of the gut microbiome in CVD development, and associated microbial communities, functions, and metabolic profiles. We also discuss CVD therapeutic interventions that target the gut microbiota such as probiotics and faecal microbiota transplantation.

The ultra-structural, metabolomic and metagenomic characterisation of the sudanese smokeless tobacco 'Toombak'.

Toombak is a smokeless tobacco produced from the Nicotiana rustica tobacco plant from Sudan. Pre-prepared and ready to buy Toombak samples were analysed using mass spectrometry (heavy metals), gas and liquid chromatography (metabolomics), 16S rRNA metagenomic sequencing (microbiome) and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and pH analysis. Chromium, cobalt, and copper were high in the pre-prepared form of Toombak while iron, tobacco specific nitrosamines (TSNAs), formaldehyde and acetaldehyde were high in both types. Firmicutes and Actinobacteria dominated Toombak. Samples of ready to buy Toombak showed inter-variational differences depending on place of purchase. We found Virgibacillus were increased in the pre-prepared form while Corynebacterium casei, Atopococus tabaci, Atopostipes suicloacalis, Oceanobacillus chironomi and Staphylococcus gallinarum were the most abundant species in the ready to buy forms. PICRUSt analysis highlighted increased activity of metal transport systems in the ready to buy samples as well as an antibiotic transport system. SEM-EDX highlighted large non-homogenous, irregular particles with increased sodium, while pH of samples was in the alkaline range. The final composition of Toombak is affected by its method of preparation and the end product has the potential to impart many negative consequences on the health of its users. TSNA levels observed in Toombak were some of the highest in the world while the micro-environment of Toombak supports a distinct microbiota profile.

Linoleate Isomerase Complex Contributes to Metabolism and Remission of DSS-Induced Colitis in Mice of Lactobacillus plantarum ZS2058.

A linoleate isomerase complex including myosin-cross-reactive antigen, short-chain dehydrogenase/oxidoreductase, and acetoacetate decarboxylase has been confirmed as the pivotal factor for conjugated linoleic acid (CLA) production in Lactobacillus plantarum. However, its role in the metabolism and health-associated benefits of Lactobacillus remain unclear. In the current study, the mild type, knockout, and complemented mutants of the linoleate isomerase complex of L. plantarum ZS2058 were used to investigate those putative effects. The metabonomic results showed that a linoleate isomerase complex could significantly influence the glycol-metabolism, lipid metabolism, and antioxidant compounds. Especially, with the stress of linoleic acid, linoleate isomerase complex knockout mutants induced the increase of several antioxidant compounds, such as glutamic acid, glycine, l-cysteine, glycerol, and l-sorbosone. Moreover, the linoleate isomerase complex played a pivotal role in ameliorating DSS-induced colitis. The knockout mutants showed effects similar to those in the DSS group, whereas complementation of the corresponding gene in the knockout mutants could restore the anti-inflammatory activity, wherein the integrity of a mucus layer was repaired, the level of pro-inflammatory cytokines decreased, and the amount of anti-inflammatory cytokines increased significantly. All the results indicated that the linoleate isomerase complex plays a key role in CLA production and metabolism as well as the health-associated benefits of L. plantarum ZS2058. These results are conducive to promote clinical trials and product development of probiotics for colitis.

Protective effect of Bifidobacterium bifidum FSDJN7O5 and Bifidobacterium breve FHNFQ23M3 on diarrhea caused by enterotoxigenic Escherichia coli.

Enterotoxigenic Escherichia coli (ETEC) is the main bacterial cause of diarrhea among children in developing countries and of traveler's diarrhea. In this study, a mouse model was used to evaluate the effect of Bifidobacterium on alleviating diarrhea caused by ETEC. The results showed that B. breve FHNFQ23M3 and B. bifidum FSDJN7O5 could relieve the symptoms of diarrhea. Both strains significantly reduced the stool water content, restored the villi structure in the jejunum and ameliorated the fecal short-chain fatty acid (SCFA) content. In addition, B. breve FHNFQ23M3 restored body weight to the level before ETEC challenge and significantly reduced interferon-γ (IFN-γ), while B. bifidum FSDJN7O5 significantly improved interleukin (IL)-10. Furthermore, all the Bifidobacterium strains used in this study could significantly downregulate tumor necrosis factor-α (TNF-α) and restore the unbalanced gut microbiota, which had a high content of pathogenic Escherichia-Shigella and low content of Blautia and Clostridium innocuum groups due to ETEC. All the results proved that Bifidobacterium could be a potential probiotic for alleviating diarrhea from ETEC infection.

Measuring Conjugated Linoleic Acid (CLA) Production by Bifidobacteria.

The biological significance of conjugated fatty acids (CFAs) has been linked to positive health effects based on biomedical, in vitro, and clinical studies. Of note, conjugated linoleic acids (CLAs) are the most widely characterized fatty acids as geometric isomers cis-9,trans-11 and trans-10,cis-12 CLA occur naturally in ruminant fats, dairy products, and hydrogenated oils. Concerning CLAs, it is known that bacterial biohydrogenation, a process whereby ruminal bacteria or starter cultures of lactic acid bacteria have the ability to synthesize CLA by altering the chemical structure of essential fatty acids via enzymatic mechanisms, produces a multitude of isomers with desirable properties. Bifidobacterium species are classed as food grade microorganisms and some of these strains harness molecular determinants that are responsible for the bioconversion of free fatty acids to CLAs. However, molecular mechanisms have yet to be fully elucidated. Reports pertaining to CLAs have been attributed to suppressing tumor growth, delaying the onset of diabetes mellitus and reducing body fat in obese individuals. Given the increased attention for their bioactive properties, we describe in this chapter the qualitative and quantitative methods used to identify and quantify CLA isomers produced by bifidobacterial strains in supplemented broth media. These approaches enable rapid detection of potential CLA producing strains and accurate measurement of fatty acids in biological matrices.