Who revealed biochemical nature of the transforming principle?

Explanation

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

1. **Understanding the Transforming Principle**: The concept of the "transforming principle" was first introduced by Frederick Griffith in his experiments with Streptococcus pneumoniae. He discovered that non-virulent bacteria could be transformed into virulent forms when exposed to heat-killed virulent bacteria.

2. **Identifying the Researchers**: The biochemical nature of this transforming principle was revealed by a group of scientists, including Oswald Avery, Colin MacLeod, and Maclyn McCarty. They built upon Griffith's work to investigate what the transforming principle actually was.

3. **Conducting the Experiment**: Avery, MacLeod, and McCarty conducted experiments in vitro (outside a living organism) to determine the biochemical nature of the transforming principle. They used the heat-killed S-type (virulent) bacteria and mixed it with non-virulent R-type bacteria.

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