Recently increasing diseases, negative progress of human health, forced consumers to consume natural products. Natural products have been difficult and expensive to procure, as they are not as abundant as before, and as a result of increasing demand. In order to meet the increasing demand, mass production has started and different industrial products are put on the market. Most of these industrial products are treated with chemicals. Although products treated with chemicals have advantages such as cheap production, length of storage and ease of use, they may have harmful effects on health and increase the demand for natural products in consumers. Therefore, biotechnological methods have recently been considered as an alternative. It is known that biotechnological methods are widely used in food industry, health industry, leather and textile production, animal feed production. More innovative and effective products should be produced by focusing on each of these applications and utilizing the power of biology and technology sciences. In order to increase the applicability of biotechnology and biotechnological methods, which are popular in recent times, we need to understand and know biotechnology very well. In this review, bioconversion methods used in the production of some natural substances, which is one of the application fields of biotechnology, are discussed.