Microflora in the Gastrointestinal Tract

Microflora in the Gastrointestinal Tract

     The Gastrointestinal Tract (or GI tract) is approximately 27 to 30 feet in length, according to the Britannica Encyclopedia (2014), and has an area of 200 – 300m2. Our GI tract contains a multitude of different bacteria; roughly 1000 bacterial cells are found in our gut with over 400 different species and subspecies.The type and number of bacteria present in our GI tract is heavily dependent on factors such as pH, peristalsis, bacterial activity, bacterial co-operation and antagonism, availability of nutrients and the constituents of our diet. Our stomach has a low pH and this acidity, paired with the rapid movement of food via peristalsis in the stomach and small intestine, lead to the low bacterial concentration in the stomach, duodenum and jejunum – approximately 100 bacteria per milliliter of gastric or intestinal content. Here, mainly acidophiles such as Lactobacilli and Streptococci can be found as they are able to withstand the high levels of acidity.

 

     In the ileum, there is a bacterial concentration of 107 - 108 which is very similar to the composition of the colon. The rise in bacterial diversity and content in the ileum is due to the increase in pH, decrease in peristalsis and low redox potential. Similarly, the colon, which is the chief site of bacterial diversity in the gut, has reduced intestinal mobility and a low redox potential which allows many microbes to colonize and grow in this area. The colon contains 99.9 % obligate aerobes in its microflora (Hao and Lee, 2004).