Escherichia coli present in human colon is

Options

A. Parasite
B. Commensal
C. Symbionts
D. Saprophyte.

Answer

**Step-by-Step Solution:**

1. **Understanding Escherichia coli (E. coli):**
- E. coli is a type of bacteria that is commonly found in the intestines of humans and other warm-blooded organisms.
- It is classified as a gram-negative, facultative anaerobic bacterium.

2. **Identifying the Role of E. coli in the Human Colon:**
- E. coli is a normal inhabitant of the human intestines and plays a significant role in the gut microbiome.
- It is important to determine whether E. coli acts as a parasite, commensal, symbiont, or saprophyte.

3. **Evaluating the Options:**
- **Parasite:** Parasites live on or in a host and cause harm. E. coli does not harm the host; instead, it coexists peacefully.
- **Commensal:** Commensals are organisms that benefit from their host without harming it. E. coli fits this definition as it is beneficial to humans by producing vitamin K2 and preventing harmful bacteria from colonizing the intestines.
- **Symbiont:** Symbionts typically have a mutualistic relationship where both organisms benefit. While E. coli does provide benefits, it is more accurately described as a commensal in this context.
- **Saprophyte:** Saprophytes feed on decaying organic matter. E. coli does not fit this category as it primarily lives in the intestines.

4. **Conclusion:**
- Based on the evaluation, E. coli present in the human colon is best described as a **commensal** organism.
- Therefore, the correct answer is **option 2: commensal**.

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