Final answer:
There are approximately 100 trillion bacteria inhabiting the human gut, including species such as Lactobacillus, E. coli, and Bacteroides. These bacteria assist in digestion, especially of plant food.
Step-by-step explanation:
The human gut is home to a diverse range of bacteria, with estimates suggesting that there are approximately 100 trillion bacteria inhabiting the gut. These bacteria include Lactobacillus and E. coli, among others. About a third of all gut bacteria belong to the species Bacteroides, which play a crucial role in helping us digest plant food.