1. High-level dietary fibre up-regulates colonic fermentation and relative abundance of saccharolytic bacteria within the human faecal microbiota in vitro BY: HANNAH HANKINS

2. Large Intestines, Microbiota, and Fiber Large intestines/Colon: Last part of the Digestive System. Responsible for removing the remaining water and nutrients from food before it is excreted. Absorb vitamins created by colonic bacteria Gut Microbiota: microscopic organisms living in the gut. About 10^11-10^12 bacteria in the colon. They compose up to 60% of your feces. Fiber: fiber is the edible parts of plants or analogous carbohydrates that are resistant to digestion and absorption in the human small intestine.

3. Fiber Dietary fiber is suggested to impact human energy metabolism in a number of ways including: regulation of intestinal transit time, digestive function through bulking and gel-form activities reducing energy density of foods acting as a substrate for carbohydrate fermentation by the colonic microbiota. Carbohydrate fermentation results in the production of short chain fatty acids: Acetate, propionate, and butyrate Help regulates lipogenesis, act as an energy source for the gut, regulate gut hormones, and impact fat storage. Certain types of dietary fiber like oligosaccharides, inulin, fructo-oligosaccharides and galacto- oligosaccharides induce bifidogenic effects within human faecal microbiota.

4. Microbiota and Health The intestinal microbiota has been linked to the aetiology or maintenance of many chronic diseases. Bowel disease Colon cancer Diseases associated with obesity. Increasing production of beneficial bacteria like bifidobacterium and lactobacillus may increase immunity, vitamin production, and inhibit pathogens.

5. Objectives and Hypothesis

6. Vessel 1 280 mL Vessel 2 300 mL Vessel 3 300 mL Proximal ColonTransverse Colon Distal Colon pH 5.5pH 6.8pH 6.2 Culture Medium: Designed to mimic the most common western-style diet in the UK. RESAZURIN: Indicator of anaerobicity Nitrogen Nitrogen Free gas pumped in to maintain anaerobic conditions Used a FerMac pH controller to pump HCl ans NaOH to maintain pH.

7. Inoculated with 100ml of 20% Faecal Inocula (2 males and 1 female)and pre-reduced PBS. Fermented in three phases (Steady States). Retention time was 36 hours long. 1. Gut Models were fed with a standard medium with initial level of dietary fibre content. 2. The level of fiber was increased three- fold with starch, inulin, guar gum, xylan, pectin, and arabinogalactin. 3. Level of fiber reduced and allowed back to normal. Samples were taken for four consecutive days for bacterial and short chain fatty acids analysis. Methods

8. Analysis Analysis used: FISH, SCFA via GC, PCR-DGGE, and statistical analysis of bacteria count. ◦FISH ◦Oligonucleotide probe to recognize certain microbiota ◦5890 Series GC system ◦calculated Short Chain Fatty acids from culture. ◦PCR-DGGE ◦PCR: amplifies replication of specific segments of DNA based on primers applies ◦DGGE: Denaturing Gradient Gel Electrophoresis- banding patterns can be used to visualize variations in microbial genetic diversity

9. Results FISH analysis shows the mean changes in bacterial changes. 5890 Series GC system to show changes in SCFA production

10. Results banding patterns show variations in microbial genetic diversity. More/thicker bands show more diversity/presence of microbiota

11. Binary Data Matrix and PCA Generated by the presence or absence of DGGE bands Red-Steady State 1 green- Steady State 2 black- Steady State 3

12. Discussion Upon the high fiber supplementation there was a relative abundance of: Bifidobacterium (p<0.05) ◦Associated with improved biomarkers of CVD and colon cancer. Eubacterium rectale-clostridium coccoides faecalibacterium prausnitzii (p<0.05) proximal colon (vessel 1) ◦Produce a majority of butyrate in the colon. ◦faecalibacterium prausnitzii aids in maintaining colonic health and reducing chances of inflammatory bowel diseases. Helps with the secretion of metabolites able to block NF- k B and IL-8 production. Lactobacillus/enterococcus (p<0.05) Ruminococcus (p<0.05) ◦Adheres to starch particles and digests cellulose ◦Carbohydrate rich environment increased the growth of this bacterium. ◦Implies the bacteria is sensitive to modulation created by starch/carbohydrate-rich diets.

13. Possible future studies and limitations of this study Since the study is In vitro, it lacks: - human cell or immune interactions - no capacity to mimic absorption of organic acids and other microbiota metabolites or conversely, - hosts secretions and water absorption. It has a small sample size (2 males and one female) FUTURE STUDIES: How different enterotypes respond to high fiber availability

14. Conclusion Mixed fiber consumption intake has a beneficial effects on the human gut microbiota composition. Continuous consumption of large quantities of high fiber foods can improve colonic health and overall well being.

15. What to Take From This FIBER IS YOUR FRIEND!!! DON’T BE AFRAID TO MIX IT UP A BIT!

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17. SFCA ACETATE Acts as a substrate for hepatic de novo lipogenesis via acetyle-coa and fatty acid synthase BUTYRATE butyrate is a major energy source for colonic mucosa. May enhance adaptive thermogenesis thus increasing energy expenditure to control body weight and markers of metabolic syndrome.

18. propionate Propionate down-regulates lipogenesis-reduced expression of fatty acid synthase