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Item Effect of iron-manganese oxide on the degradation of deoxynivalenol in feed and enhancement of growth performance and intestinal health in weaned piglets.(Elsevier B.V., 2024-10-28) Wu C; Song J; Liu X; Zhang Y; Zhou Z; Thomas DG; Wu B; Yan X; Li J; Zhang R; Wu F; Cheng C; Pu X; Wang XDeoxynivalenol (DON), a prevalent and highly toxic mycotoxin in animal feed, poses significant risks to livestock health and productivity. This study evaluates the effectiveness of iron-manganese oxide (Fe/Mn oxides) in degrading DON. The DON degradation rate of Fe/Mn oxide reached 98.46 % in a controlled solution under specific conditions (0.2 % concentration, 37-85 °C, pH 6-7, 1-minute reaction time). When applied to actual feed, it reduced DON levels by approximately 49.3 % and remained stable in simulated gastrointestinal environments of weaned piglets. A 28-day trial involving 48 weaned piglets assessed the impacts of Fe/Mn oxides on health and growth. Results indicated that piglets consuming contaminated feed without the treatment exhibited reduced growth and compromised gut integrity, which were significantly mitigated by the addition of Fe/Mn oxides. Therefore, Fe/Mn oxides effectively reduce DON in feed and alleviate adverse health effects in piglets, making them a viable option to enhance safety and performance in mycotoxin-prone environments.Item Oxalate-Degrading Bacillus subtilis Mitigates Urolithiasis in a Drosophila melanogaster Model.(American Society for Microbiology, 2020-10-01) Al KF; Daisley BA; Chanyi RM; Bjazevic J; Razvi H; Reid G; Burton JPKidney stones affect nearly 10% of the population in North America and are associated with high morbidity and recurrence, yet novel prevention strategies are lacking. Recent evidence suggests that the human gut microbiota can influence the development of nephrolithiasis, although clinical trials have been limited and inconclusive in determining the potential for microbially based interventions. Here, we used an established Drosophila melanogaster model of urolithiasis as a high-throughput screening platform for evaluation of the therapeutic potential of oxalate-degrading bacteria in calcium oxalate (CaOx) nephrolithiasis. The results demonstrated that Bacillus subtilis 168 (BS168) is a promising candidate based on its preferential growth in high oxalate concentrations, its ability to stably colonize the D. melanogaster intestinal tract for as long as 5 days, and its prevention of oxalate-induced microbiota dysbiosis. Single-dose BS168 supplementation exerted beneficial effects on D. melanogaster for as long as 14 days, decreasing stone burden in dissected Malpighian tubules and fecal excreta while increasing survival and behavioral markers of health over those of nonsupplemented lithogenic controls. These findings were complemented by in vitro experiments using the established MDCK renal cell line, which demonstrated that BS168 pretreatment prevented increased CaOx crystal adhesion and aggregation. Taking our results together, this study supports the notion that BS168 can functionally reduce CaOx stone burden in vivo through its capacity for oxalate degradation. Given the favorable safety profile of many B. subtilis strains already used as digestive aids and in fermented foods, these findings suggest that BS168 could represent a novel therapeutic adjunct to reduce the incidence of recurrent CaOx nephrolithiasis in high-risk patients.IMPORTANCE Kidney stone disease is a morbid condition that is increasing in prevalence, with few nonsurgical treatment options. The majority of stones are composed of calcium oxalate. Unlike humans, some microbes can break down oxalate, suggesting that microbial therapeutics may provide a novel treatment for kidney stone patients. This study demonstrated that Bacillus subtilis 168 (BS168) decreased stone burden, improved health, and complemented the microbiota in a Drosophila melanogaster urolithiasis model, while not exacerbating calcium oxalate aggregation or adhesion to renal cells in vitro These results identify this bacterium as a candidate for ameliorating stone formation; given that other strains of B. subtilis are components of fermented foods and are used as probiotics for digestive health, strain 168 warrants testing in humans. With the severe burden that recurrent kidney stone disease imposes on patients and the health care system, this microbial therapeutic approach could provide an inexpensive therapeutic adjunct.Item The effect of weaning food substrate on segmented filamentous bacteria in infant small intestinal immune barrier maturation : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutrition at Massey University, Palmerston North, New Zealand (School of Food and Advanced Technology)(Massey University, 2021) Oemcke, LindaAppropriate and complete maturation of the gastrointestinal tract (GIT) barriers is crucial as it contributes to overall health and wellness. Maturation of the small intestinal immunological barrier has gained interest due to GIT-associated disorders such as inflammatory bowel disease thought to be caused by improper maturation. The transition from milk-based feeding to complementary feeding in healthy infants at weaning introduces new antigens and microbes into the GIT. These changes induce immune cell production and is thought to be the final stages in the maturation process of the immunological barrier. It is during this maturation process at weaning that segmented filamentous bacteria (SFB) are thought to play a role. These Gram-positive, obligate anaerobic, spore-forming commensals have been observed in the faeces of 6–25-month-old infants and the terminal ileum of weanling rodents. The abundance of ileal and faecal SFB increases at weaning, peaks then decreases post-weaning and remains at that lower plateau throughout life. The transient abundance change of SFB has also been correlated with immune markers, immunoglobulin A (IgA) concentration in faeces and interleukin 17 (IL-17) concentration in blood plasma. The reported correlation between SFB, IgA and IL-17, and the timing at which the abundance of SFB changes at weaning, suggests that weaning foods might have an influence on changes in SFB abundance and hence on the immunological barrier. The published SFB genome identified carbohydrate metabolic and transport genes and a published study also reported an influence of complex substrates from the diet on SFB abundance. These findings suggested that a diet supplemented with complex carbohydrates may enhance the ileal SFB abundance, which had not been investigated at weaning previously. The aim therefore of this thesis was to investigate whether the complex carbohydrate inulin would influence the ileal and faecal abundances of SFB at weaning and would modulate the concentration of the GIT immune markers, IgA in faeces, and IL-17 in plasma. The hypothesis was that a weaning diet enriched with inulin would increase the peak abundance of SFB in the terminal ileum which would then enhance GIT immune barrier maturation. Initial method development showed that the temporal profile of SFB colonisation in the ileal tissue and contents of weanling rats was similar to those published for mice and infants of corresponding weaning age. Additionally, and for the first time, whole tissue homogenisation was favoured over ileal mucosal scraping as the ideal collection technique due to lower variability in whole ileal tissue data. These methods were implemented in a final study where inulin was selected because it is commonly found in weaning foods such as fruit and vegetables and is also routinely added to bovine-based milk formulas to supplement the deficit of oligosaccharides (compared to human milk). Results revealed that inulin did not influence the peak abundance of SFB, regardless of inulin dosing (0%, 2.5%, 5%, 10%) or sample type (ileal tissue, ileal contents, faeces), three days post-weaning in 24-day-old Sprague-Dawley rats. There were no differences of inulin dosing on ileal and faecal SFB abundances, blood plasma IL-17 and faecal IgA concentrations, nor between male and female rats. This outcome from the inulin intervention suggests that SFB may not utilise inulin directly or a longer period of adaptation to the inulin-supplemented diet might be required to assess if there is a long-term effect on ileal SFB abundance. The findings do not rule out other complex carbohydrates with potential influence on ileal SFB abundance. Further investigation would entail determining any interactive effects among inulin-supplemented diet, SFB abundance, and immune markers at broader time-points beyond the expected peak of SFB abundance post-weaning. In addition, analysis could be carried out to determine the abundance of other microbes relative to the predicted pre- and post-weaning SFB abundance changes. Further investigations will advance our understanding on the ability of specific food substrates to manipulate SFB and important members of the GIT microbiota and in turn support the development of high-value foods for overall health benefits in infants.Item The influence of habitual dietary intake on the responsiveness of the gut microbiota to a dietary intervention : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Manawatu, New Zealand(Massey University, 2017) Healey, Genelle RosePreliminary evidence suggests that inter-individual variability in gut microbiota response to a dietary intervention is influenced by baseline gut microbiota composition. Differing habitual dietary intakes lead to distinctions in baseline gut microbiota composition making it plausible that habitual dietary intake may also influence gut microbiota response. Prior to conducting this research no studies had been undertaken to determine whether habitual dietary intake has an impact on gut microbiota responsiveness. Therefore, the aim of this research was to investigate the influence habitual dietary intake as on gut microbiota response to a dietary intervention. Initially, secondary data analysis was conducted to determine whether there was any support for the hypothesis that individuals with differing habitual dietary intakes would have gut microbiota that respond in a distinctive manner to a dietary intervention. The secondary data analysis results demonstrated that dietary groups rich in dietary fibre had the greatest impact on gut microbiota responsiveness. An in vitro three-stage colonic model system study was conducted to determine whether media with differing fermentable carbohydrate (i.e. dietary fibre) contents influenced gut microbiota response to an inulin-type fructan prebiotic. It was demonstrated that differing prebiotic driven changes in organic acids and bacterial taxa occurred between the low (LFC) and high fermentable carbohydrate (HFC) content media. The results of the secondary data analysis and in vitro study provided evidence to suggest that a human intervention study was warranted. A randomised, double-blind, placebo-controlled, cross-over, human intervention study in 34 healthy participants was undertaken to determine whether habitual dietary fibre intake influenced gut microbiota response to an inulin-type fructan prebiotic. The results of the human intervention study demonstrated that the low habitual dietary fibre (LDF) group harboured gut microbiota that were less responsive to the inulin-type fructan prebiotic than the high habitual dietary fibre (HDF) group. Future studies which aim to modulate the gut microbiota via dietary change or to determine the prebiotic potential of a novel fermentable substrate should take habitual dietary fibre intakes into consideration when recruiting participants or analysing the data. This will help reduce the confounding influence of inter-individual variability in gut microbiota responsiveness and ensure the true efficacy of a dietary intervention is demonstrated.Item Effect of Faecalibacterium prausnitzii on intestinal barrier function and immune homeostasis : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science, Massey University, Manawatū, New Zealand(Massey University, 2017) Maier, EvaVarious gastrointestinal (GI) diseases, for example inflammatory bowel disease, are linked to impaired barrier function, chronic inflammation and dysbiosis of the resident microbiota. Faecalibacterium prausnitzii, an abundant obligate anaerobe of the healthy human microbiota, has reduced abundance in the GI tract of people with these diseases, and has been suggested to exert beneficial effects. Only a few studies have investigated its mechanisms of action, partly due to the difficulty of co-culturing live obligate anaerobes with oxygen-requiring human cells. The novel apical anaerobic co-culture model used in this study allows this co-culture through the separation of anaerobic and aerobic compartments. This model was used to investigate the effects of live F. prausnitzii (strains A2-165, ATCC 27768 and HTF-F) on intestinal barrier integrity, measured by transepithelial electrical resistance (TEER) of the intestinal epithelial cell line Caco-2, and on immune homeostasis, specifically on Toll-like receptor (TLR) activation. Method development was required to adapt these assays to the novel model and to optimise the growth of F. prausnitzii co-cultured with Caco-2 cells and TLR-expressing cell lines while maintaining their viabilities. Firstly, the optimised co-culture conditions were used to determine the effect of the three F. prausnitzii strains on barrier integrity of healthy and tumour necrosis factor alpha (TNF-α) treated Caco-2 cells. Live and growing F. prausnitzii did not alter the TEER across healthy Caco-2 cells. However, under TNF-α mediated inflammatory conditions, dead F. prausnitzii decreased TEER, whereas live bacteria maintained TEER. Secondly, the TLR activation assay was adapted to be carried out in the novel model. Using the adapted assay conditions it was determined that live F. prausnitzii induced greater TLR2 and TLR2/6 activation than dead F. prausnitzii. Collectively, these results indicate greater immuno-stimulatory effects of live F. prausnitzii, via TLR2 activation, and this effect is potentially linked to its barrier maintaining properties, because previous research showed enhancement of barrier integrity induced by TLR2 signalling. This new knowledge contributes to the understanding of how F. prausnitzii may maintain immune homeostasis in the GI tract. Unravelling the biological mechanisms used by prevalent species of the human microbiota, such as F. prausnitzii, will ultimately allow better comprehension of microbial regulation of GI function.Item Studies on the protective role of probiotics and milk calcium on Salmonella Typhimurium infection in mice : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Nutritional Science at Massey University, Palmerston North, New Zealand(Massey University, 2000) Lin, HaiThe current studies were carried out to evaluate the efficacy of a newly identified LAB strain - DR10TM (Bifidobacterium lactis) on host immunity and susceptibility to Salmonella typhimurium (S. typhimurium) infection in mice. In addition, the effect of elevated milk calcium levels combined with DR10TM was studied in mice infected with S. typhimurium. After initially establishing a murine infection model, the effect and efficacy of DR10TM in preventing S. typhimurium infection and stimulating immunity was examined. The results showed that DR10TM could significantly enhance resistance against S. typhimurium infection and stimulate a wide range of immune parameters including non-specific and specific immune responses. In another study the S. typhimurium infection model was used to examine the effect of milk calcium and the combination of different amounts of milk calcium with DR10TM on host immunity and prevention of S. typhimurium infection in mice. These results demonstrated that milk calcium was very effective in reducing the severity of infection and a high amount of milk calcium combined with DR10TM increased the ability of DR10TM to prevent S. typhimurium infection. The findings of the current study were significant in that they demonstrated the effect and efficacy of DR10TM on promoting enhanced resistance to enteric infection and stimulating immunity, provided additional evidence of the role played by the enhanced immune system in protecting against enteric infection, and ascertained the synergism between milk calcium and LAB in the prevention of S. typhimurium infection.Item Probiotic Bifidobacterium lactis HN019 enhances the resistance and immunity against enteric pathogens : a thesis presented in partial fulfilment of the requirements for masters degree in nutritional science at Massey University(Massey University, 2001) Qu, ShaogangProbiotics are defined as a group of live microorganisms, including some microbial stimulants that exert health promoting effects, such as the maintenance of a normal intestinal microbiotia, increased nutritional value of foods, anticarcinogenic activity, reduction of serum cholesterol levels, alleviation of lactose intolerance and stimulation of the immune system. Some of strains of lactic acid bacteria (LAB) are representative probiotics. The objective of this study was to examine the immunomodulatory and antiinfection properties of a new identified LAB strain- Bifidobacterium lactis using two animal models. Two experiments were conducted and reported in this thesis. In the first experiment, a piglet weaning diarrhoea model was used to test the efficacy of Bifidobacterium lactis HN019 protecting against diarrhoea associated with Rotavirus and E. coli. 17 three-week-old piglets were allocated into two groups balanced for liveweight and litter of origin. The first group (n=8) was orally administered B. lactis HN019 (109 cfu/piglet/day) through the experiment; the second group (n=9) was not given B. lactis HN019 (control). After one week, the animals were penned individually and weaned onto a weaner diet. Blood samples were taken to measure the antibody responses, cell proliferation, and phagocytic activity of leukocytes (monocytes and neutrocytes). Also the effect of B. lactis HN019 on weaning diarrhoea was assessed by monitoring the severity of diarrhoea, feed intake and liveweight gain of the piglets on the weaner diet. Compared to the controls, piglets receiving B. lactis HN019 had lower severity of weaning diarrhoea, higher survival rate and feed conversion efficiency (or liveweight gain). The protection was associated with lower levels of faecal rotavirus and E. coli shedding, higher phagocytie activities and cell proliferative response to mitogens, and higher specific antibody titers. These results suggest that dietary B. lactis can reduce the severity of weaning diarrhoea associated with rotavirus and E. coli, and the probiotic is associated with enhanced immune responsiveness. In the second experiment, the protective effects of Bifidobacterium lactis HN019 against E. coli O157:H7 and associated immunological parameters were investigated using murine models. After one week acclimatisation on a skim milk powder (SMP)-based diet, eighty-six BALB/c and C57 mice were selected and randomised to two treatment groups. One group was fed on the SMP-based diet until the end of the experiment, while the other group was fed the SMP-based diet supplemented with B. lactis HN019 (3 x 108 cfu/g). After one week on these diets, mice were intragastrically inoculated with 0.1 ml E. coli O157:H7 suspension (109 cfu/ml). Protection against E. coli O157:H7 infection was assessed by monitoring the morbidity, feed intake, bacterial translocation to visceral tissues (spleen and liver) and immune responsiveness. Phagocytic activities of blood and peritoneal cells, and antibody titres against E. coli O157:H7 in intestinal content were also measured. The results showed that B. lactis HN019-fed mice conferred a significant degree of protection against E. coli O157:H7 challenge in comparison to the control mice that did not receive B. lactis HN019. Protection included lower morbidity and higher post-challenge feed intake, reduced pathogen translocation to blood, spleen and liver, as well as significantly higher phagocytic activities of blood and peritoneal cells and anti-E. coli IgA level in gut content. These results suggest that B. lactis HN019 can enhance the host resistance to E. coli O157:H7 and that the protection is associated with enhanced immune functions. In summary, potential immune enhancing effects of B. lactis HN019 were investigated in one pig trial and one mice trial. The results showed that supplement of B. lactis HN019 relieved diarrhoea associated with rotavirus and E. coli infection in piglets and enhance the host resistance to E. coli Ol57:117 challenge in mice. Immunological measurements indicated B. lactis HN019 fed groups had significant higher phagocytosis and anti-E. coli IgA levels. And the pathogen shedding was also reduced in B. lactis HN019 fed groups. As concluded, B. lactis HN019 can provide a protective role against special enteric pathogen infection by its immunomodulatory effects.Item Interactions between commensal obligate anaerobes and human intestinal cells : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Manawatu, New Zealand(Massey University, 2013) Ulluwishewa, DulanthaThe human intestinal epithelium is formed by a single layer of epithelial cells which regulates intestinal barrier permeability. Increased permeability can result in the entry of potentially harmful compounds into the body, and is implicated in autoimmune, inflammatory and atopic diseases. The intestinal tract is inhabited by an estimated 1014 microbes and it is increasingly evident that they affect intestinal barrier function. However, over 90% of commensal intestinal bacteria are obligate anaerobes, making it difficult to co-culture them with oxygen-requiring mammalian cells in vitro. To investigate the interactions between obligate anaerobes and epithelial cells that regulate the intestinal barrier, an apical anaerobic model of the human intestinal epithelium, which utilises a dual-environment co-culture chamber, was developed and validated. The chamber allowed for polarised monolayers of the intestinal cell line Caco-2 to be grown such that the apical (luminal) side was exposed to an anaerobic environment, while maintaining an aerobic basal side. The cell viability and barrier function of Caco-2 monolayers was unaffected by culture in the apical anaerobic model for at least 12 hours. Global gene expression analysis predicted upregulation of cell survival and proliferation in Caco-2 cells cultured in the apical anaerobic model, compared to Caco-2 cells grown under conventional conditions, suggesting an adaptation of the Caco-2 cells to a lower supply of oxygen. The apical anaerobic model was used to co-culture the commensal obligate anaerobe Faecalibacterium prausnitzii with Caco-2 cells. The survival of F. prausnitzii was improved in the anaerobic apical environment compared to when cultured in an aerobic atmosphere. Live F. prausnitzii, but not non-viable (UV-killed) F. prausnitzii, were shown to increase permeability across Caco-2 monolayers. Furthermore, global gene expression analysis suggested that live F. prausnitzii cells have more profound effects on Caco-2 cells than non-viable F. prausnitzii, illustrating the importance of maintaining viability of obligate anaerobes in an in vitro co-culture system. The apical anaerobic model can be used to gain insights into the mechanisms of crosstalk between commensal obligate anaerobic bacteria and intestinal cells, and new knowledge generated using this model will assist in the development of strategies to improve intestinal barrier function.