Localization And Cloning Of Gene Cluster Involved In Antibiotics 5102-Ⅲ Production From Streptomyces Hygroscopicus 10-22

Streptomyces hygroscopicus Subsp. Yingchengensis 10-22 is an important agricultural strain which produces at least four antifungal antibiotics named as antibiotic 5102-I, 5102-II, 5102-III, 5102-IV respectively. Antibiotic 5102-III, whose structure is unknown, is useful for the control of cotton wilt caused by Fusarium Oxysporum.Many Streptomyces species exhibit a very high degree of genetic instability which is usually manifested as genomic rearrangement such as large deletion, and high-level DNA amplification of those sequences flanking the deletion. Protoplast regeneration, treatment of mutagenesis and other unknown factors can increase the genomic inherent instability, which usually affects the following five phenotypic traits: sporulation, pigmentation, colony morphology, antibiotic production and antibiotic resistance.As far as 10-22 is concerned, the unstable region compasses the 170-, 210-A, 210-B, 280-, 300-, 500-, 680-, 900-, and 1300-A AseI fragments. 21 blocked strains for antibiotic 5102-III production were obtained in a screening project. PFGE analysis of these 21 blocked strains revealed a common chromosomal deletion in the 300Kb Asel fragment which might be responsible for antibiotic 5102-III biosynthesis. So the 300Kb fragment was recovered and used as probe to hybridize with 10-22 genomic library .Cosmids in this region were aligned and suitable fragments in this region were selected and used further for the construction of gene replacement plasmids. 16 replacement plasmids fortwo different regions were obtained, but haven't been introduced into 10-22 successfully. 42 cosmids in this region were introduced into a heterogeneous host ZX64, one transformant exhibited a very faint inhibit activity against Fusarium Oxysporum when growed on a medium with thiostrepton . Repeated results are required and the experiment for confirming the result is in progress.