1. Escherichia coli (E. coli): A well-known bacterium, often found in the intestines of humans and animals. Most strains are harmless, but some can cause food poisoning.

2. Lactobacillus: A genus of bacteria used in the production of yogurt, cheese, and other fermented foods. They are also found naturally in the human gut.

3. Staphylococcus aureus: A common bacterium found on the skin and in the nose of humans. It can cause a range of infections, from skin infections to pneumonia.

4. Streptococcus pneumoniae: A bacterium that can cause pneumonia, ear infections, and meningitis. It is also a common cause of bacterial infections in children.

5. Salmonella enterica: A bacterium that can cause food poisoning, usually through contaminated food. It is responsible for a wide variety of illnesses, ranging from mild diarrhea to life-threatening infections.