HIGH-LEVEL ATP PRODUCTION BY A GENETICALLY-ENGINEERED CANDIDA YEAST

Previous studies of ATP production with the methylotrophic yeast, Candida boidinii, suggested that the phosphorylation of AMP catalyzed by adenylate kinase (ADK) was rate-limiting. To investigate whether the enhancement of ADK activity in C. boidinii cells would improve ATP productivity, the Saccharomyces cerevisiae ADK1 gene encoding ADK was expressed in C. boidinii under the C. boidinii AOD1 promoter. Methanol-induced transformants had 10,000-fold enhanced levels of ADK activity and produced 23-fold more ATP from adenosine when compared to the control, parent strain. In a pH-controlled reaction system with successive adenosine-feeding, the ATP concentration in the reaction mixture reached 230 mM (117 g/l) over 45 hours, and was easily purified with an overall yield of 78 percent.