Final answer:
Escherichia coli (E. coli) is a rod-shaped bacterium commonly found in the human digestive tract; most strains are helpful, but some can cause diseases. Clostridium difficile is another rod-shaped bacterium that can cause severe intestinal issues. Bacteroides thetaiotaomicron is a beneficial rod-shaped bacterium that helps digest complex plant materials.
Step-by-step explanation:
Escherichia coli, commonly abbreviated as E. coli, is a gram-negative, rod-shaped bacterium that lives in the digestive tract of humans and other mammals. This organism is a common member of the normal microbiota of the colon, and most strains are benign and play a beneficial role in the gut. However, some strains can be pathogenic and cause gastrointestinal diseases, such as diarrhoea. These harmful strains typically have additional virulence factors that promote colonization of the colon or produce toxins.
Another example of a rod-shaped bacterium in the human digestive system is Clostridium difficile, which is a gram-positive organism. C. difficile is known to cause severe colitis and diarrhoea, especially after the normal gut microbiota is disrupted by antibiotics. Other notable rod-shaped bacteria include Bacteroides thetaiotaomicron, a mutualistic bacterium that aids in digesting complex plant materials, contributing to human metabolic processes.
Understanding the role of different bacterial species in the human digestive system is essential for recognizing the balance between helpful and harmful microbiota, their impact on health, and how certain conditions, like antibiotic use, can disrupt this balance and lead to infections.