Protease-deficient strains of the methylotrophic yeast Pichia methanolica and materials and methods for generating such strains are disclosed. The strains have a functional deficiency in a vacuolar protease, such as proteinase A or proteinase B. The strains are useful as hosts for the expression of heterologous...http://www.google.com/patents/US6153424?utm_source=gb-gplus-sharePatent US6153424 - Protease-deficient strains of Pichia methanolica
