Streptomyces venezuelae ISP5230 could produce N-dichloroacyl phenylpropanoid antibiotic chloramphenicol (Cm) and angucycline glycoside jadomycin B (JdB).Cm is produced in response to unbalanced growth,while JdB only under additional stress such as heat shock or ethanol toxicity.The gene clusters for biosynthesis of Cm (cml) and JdB (jad) have been cloned [1].Unusually,the cml gene cluster lacks a pathway-specific regulator; while the jad cluster contains an activator gene (jadR 1)and a repressor gene (jadR2) [2].JadR1could activate the transcription of the first structure gone (jadJ):JdB could directly bind to JadR1 and terminate its activation [3].