Prebiotics, Probiotics, & Symbiotics

Question 1

Define intestinal microbiota

Answer 1

Bacteria, viruses, fungi, arachaea, protozoa; # of organisms > 10x cells in the body

Question 2

Define intestinal microbiome

Answer 2

Mutual interaction of the microbiota with the host cells; all the genes contained in the microbiota

Question 3

What are the various mechanisms that control the bacterial population in the GI tract?

Answer 3

• Gastric acid
• bile
• intestinal motility
• intestinal mucus
• immune responses
• bacteria

Question 4

What is a prebiotic?

Answer 4

Nondigestible dietary carbs that promote growth of “good” bacteria and possess short chain FAs

e.g. fructooligosaccharides, bran, psyllium

Question 5

What is a probiotic?

Answer 5

Living microorganisms that impart a health benefit, survive gastric acid and bile in SI/colon, and they improve epithelial barrier, modulate immune system, and inhibit pathogen colonization

• ensure you get from reputable manufacturer and 1x10⁸ - 1x10¹² cfu/g

Question 6

What is a symbiotic?

Answer 6

A mutual interaction between 2 organisms

Question 7

What are the pros and cons of bacterial cultures?

Answer 7

Pros: viability, susceptibility, genotypes analysis, metabolism, virulence

Cons: optimal growth requirements, anaerobic culture needs, synergism for growth, <5% culturable

Question 8

What things can you test for microbiota RNA and DNA?

Answer 8

Intestinal contents, tissue biopsies, and feces

Question 9

What can you do with PCR?

Answer 9

Amplify specific genes that you would like to analyze (16s rRNA for bacteria)

Question 10

What are you examining when performing an analysis of amplicons?

Answer 10

Bacterial “fingerprint” - the phylogenetic info of the microbiota present

Question 11

How would you perform quantification of the organisms in the microbiota?

Answer 11

Quantitative real time PCR (qPCR), or fluorescent in-situ hybridization (FISH)

Question 12

What is the difference between metagenomics and transcriptomics?

Answer 12

Metagenomics - gene content (core microbiome)

Transcriptomics - gene expression

Question 13

What are the roles of the microbiota?

Answer 13

• Immunity - development of the immune system (TLRs: communication)
• host defense - bacteriocins (inhibits bact growth)
• colonization resistance (compete for O2, nutrients, adhesion sites; creates physiologically restrictive barrier)
• energy regulation - fermentation (VFAs)

Question 14

GI disease in relation to the microbiota can result when what three things happen?

Answer 14

Pathogen colonization, overgrowth of commensal organisms, or altered communication

Question 15

What are 3 common pathogens that colonize the GI tract, causing disease?

Answer 15

Salmonella, C. Difficile, Campylobacter

Question 16

What are some examples of what occurs when there is an overgrowth of commensalism organisms?

Answer 16

• “Intestinal dysbiosis;” antibiotic responsive diarrhea (SIBO)
• EPI —> SIBO
• surgical interventions that cause altered motility

Question 17

What is an example of GI disease that occurs when there is altered communication within the microbiota?

Answer 17

Inflammatory bowel disease - TLRs (alterations in T cells), shifts in bacteria toward gram negatives, histiocytic ulcerative colitis