Effect of casamino acid on intergeneric conjugation in rapamycin-producing Streptomyces hygroscopicus ATCC29253

Abstract:

Abstract:［Objective］Streptomyces hygroscopicus ATCC29253 has attracted much interests due to its capacity of producing various secondary metabolites with strong bioactivities，including immunosuppressant rapamycin，nigericin，hexaenes，elaiophylin and hygrocins． ［Objective］To investigate biosynthetic pathway of these metabolites and construct high-yield strains by genetic engineering，establishment of a highly efficient genetic manipulation system is critically required in this strain． ［Methods］We tested the effects of conjugation media and donor strains on conjugal transfer from Escherichia coli to S． hygroscopicus ATCC29253 and other Streptomycetes． ［Results］ We found that both casamino acid and MgCl2 supplemented in conjugation media improved conjugation frequency in S． hygroscopicus ATCC29253. A random experiment led to the disclosure of an optimal combination of casamino acid and MgCl2 by which the conjugation frequency in S． hygroscopicus reached 1. 5 × 10 － 4 ． Meanwhile，we also found significant changes in conjugation frequencies of S．lividans，S． albus and S． avermitilis when casamino acid was supplemented in conjugation media． ［Conclusion］Casamino acid has significant influence on conjugation frequency in not only S． hygroscopicus ATCC29253 but also other Streptomyces such as S． lividans，S． albus and S． avermitilis．