Effects of phosphate limitation on agarase production by Streptomyces lividans TK21

Abstract

The dagA gene from Streptomyces coelicolor, encoding an extracellularagarase, has been expressed in Streptomyces lividans on a multicopyplasmid. Chemostat cultures were used to investigate the influenceof phosphate limitation on the synthesis and secretion of this enzyme.The strain was cultivated with glucose as the carbon source and magnesiumor phosphate as growth-limiting substrates and samples used to determinedagA transcription, agarase secretion and alkaline phosphatase activityunder the various limitations. The data show that, compared to growthunder magnesium limitation, phosphate-limited cells show increasesin dagA transcription, the rate of agarase production and secretion,and alkaline phosphatase activity.