Final answer:
The gut microbiome is predominantly composed of the phyla Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, and Fusobacteria, with Bacteroides being particularly prevalent.
Step-by-step explanation:
The predominant phyla that compose the gut microbiome include Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, and Fusobacteria. Within these phyla, Bacteroides are particularly abundant, making up about 30% of the entire gut microbiome. These bacteria are primarily mutualistic, providing benefits such as preventing pathogens from colonizing the large intestine. Other significant members of the gut microbiome include Firmicutes bacteria which, along with Bacteroidetes, represent the vast majority of microbes in the intestines.
These microbial communities are highly influenced by factors such as diet, age, and host health, and their composition varies among individuals. However, the aforementioned phyla demonstrate broad prevalence across different human populations.