A total of 39 microbes were screened for the ability to selectively N-demethylate (3R,5S,E)-7-(4-(4-fluorophenyl)-6-isopropyl-2-(methyl(1-methyl-1H-1,2,4-triazol-5-yl)aminopyrimidin-5-yl)-3,5-dihydroxy-hept-6-enoic acid (I), a potential drug for lowering blood cholesterol levels. Two Streptomyces species were found to carry out the desired N-demethylation. Bioconversion by Streptomyces griseus A.T.C.C. 13273 and product recovery were scaled up to the multi-gram level.