Pichia pastorishas become a highly successful system for the expression of heterologous genes. Several factors have contributed to its rapid acceptance, the most important of which include:
| 1. | A promoter derived from the alcohol oxidase I (AOX1) gene ofP. pastoristhat is uniquely suited for the controlled expression of foreign genes; |
| 2. | The similarity of techniques needed for the molecular genetic manipulation ofP. pastoristo those ofSaccharomyces cerevisiae, one of the most well-characterized experimental systems in modern biology; |
| 3. | The strong preference ofP. pastorisfor respiratory growth, a key physiological trait that greatly facilitates its culturing at high cell densities relative to fermentative yeasts; and |
| 4. | A 1993 decision by Phillips Petroleum Company (continued by Research Corporation Technologies [RTC]) to release theP. pastorisexpression system to academic research laboratories, the consequence of which has been an explosion in the knowledge base of the system (Fig. 1 ). |
