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44 PROCEEDINGS OF INTERNATIONAL SCIENTIFIC CONFERENCE ON APPLIED BIOTECHNOLOGYwere generally cultured in Luria-Bertani (LB) broth or on LB agar plates at 37%u00b0C supplemented with the appropriate antibiotics at the following concentrations: ampicillin, 100 %u03bcg/ml; chloramphenicol, 25-100 %u03bcg/ml; apramycin, 100 mg/ml and kanamycin, 35-100 %u03bcg/ml. In case for cloning the vectors containing lacZ, 0.4 mM IPTG and 40 mg/ml of X-gal were included in the LB agar plates for screening of cloned transformants.Genomic DNA from Streptomyces strains were isolated using the standard protocol [10]. Plasmids from Streptomyces species or E. coli were isolated according to the standard protocol [11]. S. chromofuscus and its recombinant were however grown on ISP medium 2 (yeast extract 0.4%, malt extract 1%, and glucose 0.4%) for seed culture. For production of the metabolites, 4% of seed was inoculated into 5 L fermenter containing 3.5 L of production media [12] and fermented for 8 days at 28%u00b0C. Table 1. List of bacterial strains and plasmids used in the studyStrains/Vectors Description SourceS. chromofuscus ATCC 49982herboxidiene producer ATCCS. chromofuscus %u0394M8DHCatalytically inactivated module 8 DH containing strain of S. chromofuscusThis studyE. coli XL-1 Blue %u0394(mcrA)183%u0394(mcrCB-hsdSMR-mrr)173 endA1supE44 thi-1 recA1 gyrA96 relA1 lacStratagene La Jolla, CAE. coli ET-12567 DNA demethylating strain (dam- dcm- hsdS cmR)John Innes Center, UKpGEM%u00ae-T Easy E. coli TA cloning vector, AmpR Promega, USApKC1139 Multi copy E. coli-Streptomyces shuttle vector used for in-frame deletion[11]2.2. Construction of recombinant plasmidsThe gene fragment from the module 8 of herboxidiene PKS was PCR amplified using the genomic DNA of S. chromofuscus as