In microbial cell culture, carbon sources are required to provide energy and as building blocks for cellular components.
- Cereal grains are rich in carbohydrates and serve as an important carbon source for microbial growth.
- Olive oil can be a carbon source but is less commonly used in typical microbial cultures.
- Ammonium salts provide nitrogen, not carbon.
- Growth factors are organic compounds required in small amounts and are not carbon sources.
Thus, the correct answer is (B) Cereal grains.