D-Lyxose as a substrate for Streptomyces D-xylose isomerase

Results are presented which show that the D-xylose isomerases present in Streptomyces olivaceus and Streptomyces phaeochromogenes NRRL B-3559 are incapable of utilizing D-lyxose as a substrate. The implications of these findings as related to the use of D-lyxose in the selection of constitutive mutants are discussed.