Characterization of metabolites in intact Streptomyces citricolor culture supernatants using high-resolution nuclear magnetic resonance and directly coupled high-pressure liquid chromatography-nuclear magnetic resonance spectroscopy - Abel,C.BL.; Lindon,J.C.; Noble,D.; Rudd,B.AM.; Sidebottom,P.J.; Nicholson,J.K. (Anal Biochem, 1999)