State the best known contribution of Robert Koch.

Explanation

**Step-by-Step Text Solution:**

1. **Introduction to Robert Koch**: Robert Koch was a prominent German scientist known as the "father of bacteriology." His work laid the foundation for the study of bacteria and their role in diseases.

2. **The Golden Age of Bacteriology**: Koch's research took place during the period from the 1860s to 1910, which is often referred to as the golden age of bacteriology. This era was marked by significant advancements in understanding bacteria and their impact on human health.

3. **Koch's Postulates**: One of Koch's most significant contributions is the formulation of Koch's postulates, which are a set of criteria used to establish a causal relationship between a microorganism and a disease. These postulates state that:
- A specific microorganism must be found in abundance in all organisms suffering from the disease.
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