Relationships between humans and micro biomes

Majority of which are bacteria. These bacteria are as old as two and a half billion years. How does the topic relate to the discussion between competition and diversity in shaping diversity? There has been a discovery that some bacteria are very helpful in the bodies of organisms, for example, some bacteria are useful in the synthesizing of the enzymes that are needed to make vitamins from scratch. Bacteria are useful in breaking down food components which would be indigestible in absence of the bacteria a good example is the Bacteroides thetaiotaomicron which helps in breaking down large complex carbohydrates. Therefore microorganism sometimes relates positively to the good of the bodies. There is also a discovery that some novel proteins are associated with metabolization of sugars and Amino acids(Peterson & jane2009).