DEVELOPMENT OF CHAINIA AS A HOST FOR XYLANASE GENE CLONING - EVIDENCEFOR OCCURRENCE OF A RESTRICTION-MODIFICATION SYSTEM

Conditions for genetic transformation of the xylanase-negative (X(-)) strain of Chainia with pIJ 702 were optimized. The growth of Chainia a t 30 degrees C for 36 - 40 h and addition of geletin (1%) to the mediu m resulted In the maximum yield of protoplasts and regeneration effici ency. Poor transformation efficiency of Chainia (X(-)) protoplasts by native pIJ 702 versus improved efficiency (16 transformants ug(-1) of plasmid DNA) by prior heating of protoplasts at 42 degrees C for 10 mi n suggests the occurrence of a restriction system in Chainia. Increase d transformation efficiency by passage of the plasmid through Chainia together with the altered methylation status of the transformant plasm id presents evidence for the existence of an operative modification sy stem in Chainia. Development of thiostrepton resistance and formation of melamin pigment in Chainia (X(-)) by transformation with pIJ 702 re veal that genes from Streptomyces can be functionally expressed by Cha inia (X(-)).