Rhamnose and forosamine are two essential deoxysugars components of spinosad.Four genes involved in the biosynthesis of rhamnose and forosamine,i.e.gtt (encoding NDP-glucose synthase),gdh (encoding NDP-glucose dehydratase),epi (encoding epimerase) and kre (encoding 4′-ketoreductase),are not located together with the spinosad biosynthetic gene cluster,but distributed in 3 scattered loci in the chromosome of Saccharopolyspora spinosa NRRL18395.To get an integral spinosad biosynthetic pathway,the four genes were cloned by constructing a genomic library and PCR amplifying from S.spinosa NRRL18395.The 4 genes were successively assembled into an integrative vector to construct an expression vector for biosynthesis of rhamnose and forosamine in heterologous hosts.