Microbiota and Probiotics

Microbiota

Community of micro-organisms in a particular environment

Microbiome

Collection of microbes and their genomes

Metagenomics

The study of genetic material of environmental samples

Where are most microbiota located?

Gastrointestinal tract

Oxygen difference from stomach to colon

stomach is aerobic, colon is anaerobic

pH difference from stomach to colon

Stomach is more acidic than colon

Microbial mass difference from stomach to colon

microbial biomass greater in colon than stomach

What factors affect microbiota (controllable)

• feeding methods

• medication

• dietary habits

• environment

• lifestyle

What factors affect microbiota (uncontrollable)

• gestational age

• delivery mode

• genetics

• age

Nutritional roles of gut microbiota

• Digest non-digestible dietary fibers

• produce short-chain fatty acids

• synthesize some essential amino acids

• facilitate absorption of minerals

Metabolic roles of gut microbiota

• Production of gastrointestinal mucus

• irrigation of intestinal cells

• enzymatic activity of the mucosa (helps maturation of the gut)

Immunological/defensive roles of gut microbiota

• Teach immune system to identify pathogens

• defend against harmful microorganisms

• degrade toxic compounds

• release antimicrobial molecules against pathogenic bacteria

When does gut microbial development begin?

At birth, from mother’s placenta

Factors affecting infant microbiota

Delivery and feeding methods

Dysbiosis

Imbalance of microbiota associated with unhealthy outcomes

Clostridium difficile infection (CDI)

Gastrointestinal infection caused by depletion of bacteria that produce butyrate

Inflammatory bowel disease (IBD)

Autoimmune disease caused by damaged intestinal mucosal barrier → reduced butyrate-producing bacteria

Butyrate

Short-chain fatty acid that is the main energy source for colonocytes

Colorectal Cancer (CRC)

evidence suggests that gut microbiome is related to CRC

Effect of early-life antibiotic use

Can affect microbiota (not mature at young age)

Early-age antibiotic disruption

• mild antibiotic disruption → obesity

• Heavily affected by antibiotics → malnourishment/underweight

Probiotics

Live microorganisms which produce a health benefit on the host when administered

Prebiotics

Substances utilized by microorganisms for a health benefit on host

Synbiotics

Combination of probiotics and prebiotics

Postbiotics

Preparation of inanimate microorganisms that produce a health benefit on host

Bifidobacteria

Found in gut microbiota of breast-fed infants, clinical benefits against diarrhea, constipation, IBD, CRC

Lactobacilli

Lactic-acid producing bacteria, clinical benefits against H.pylori infection and allergies

Fecal microbiota transplant

Stool of patient with healthy microbiota → medication → ingested or inserted through colonoscopy