Abstract: In several streptomycetes, AdpA is a pleiotropic transcription factor involved in regulation of morphological development and secondary metabolites biosynthesis. The relevance of AdpA to morphological development and toyocamycin (TM) production in Streptomyces diastatochromogenes 1628was investigated in this paper.Firstly, 1263 bp adpA_sd gene (GenBank accession No. JX847412) was successfully cloned from S. diastatochromogenes 1628 by using degenerate primer. The deduced amino acid sequence of AdpA_sd showed similarity to AdpA_g(80.7%) of S. griseus and AdpA_c (78.9%) of S. coelicolor, respectively. Subsequently, adpA_sd gene was placed under control of the PermE^* in plasmid pIB139 to generate pIB139-adpA_sd. The constructed plasmid pIB139-adpA_sd was introduced by using intergeneric conjugation and integrated into chromosome of rifampicin resistance (Rif^r) mutants 1628-T15 (high-level TM producer) and 1628-T62 (low-level TM producer, poor ability of sporulation), which were isolated and selected by using ribosome engineering technology, to create recombinant strains 1628-T15A and 1628-T62A, respectively. The results indicated that compared with that of control strain 1628-T62, sporulation of recombinant strain 1628-T62A was recovered with a certain degree. In contrast, there was no significant difference between control strain 1628-T15 and recombinant strain 1628-T15A in term of morphological differentiation. Moreover, at flask-shake fermentation condition, TM production of strain 1628-T62A was improved 3-times higher than that of control 1628-T62, while recombinant strain 1628-T15A showed only a slight increase in TM production, compared with control strain 1628-T15. These data confirm that adpA_sd gene is involved in morphological differentiation and TM biosynthesis in S. diastatochromogenes 1628. Also, this work will provide the basis for studying regulatory mechanism of adpA_sd at molecular level in S. diastatochromogenes.

Key words: Streptomyces diastatochromogenes 1628, AdpA_sd, morphological differentiation, toyocamycin