Microbiota of the large intestine

Gut microbiota is the community of microorganisms in the gastrointestinal tract. They are mainly responsible for the final stage of digestion. They ferment remaining carbohydrates and release hydrogen, carbon dioxide, and methane gases. They also convert proteins to amino acids and break them down into simpler substances. One of the bacterial product groups is vitamins that are crucial for normal metabolism, thus absorbed in the large intestine.

Apart from assisting in the digestion and breakdown of food, microbiota also influences the host organism's immune response, behavior, and mood.

There are two major groups of bacteria dominating the gastrointestinal tract: Firmicutes (Lactobacillus and Streptococcus species) at 65% of the total, and Bacteroidetes at around 30%. The remaining 5% comprises primitive bacterial groups like E.coli and Bifidobacteria species. In reality, each person has a unique profile of microbial species.