A new streptomycin group antibiotic produced by Streptomyces sioyaensis.

Sir: A new antibiotic, 6"'-O-a-n-mannopyranosyl mannosidostreptomycin has been isolated from the culture filtrate of strain MD753-C2, together with streptomycin and mannosidostreptomycin. This strain has been classified as Streptomyces sioyaensis1) which is a new streptomycin-producer. In this communication, the isolation, characterization and structural elucidation of the antibiotic are reported. S. sioyaensis MD753-C2 on an asparagineglucose agar slant was inoculated into a medium (110 ml) containing starch 2.0 %, glucose 0.05 %, soybean meal 2.5 %, Peptone 0.1 %, NaCl 0.3 %, CaCl2 0.1 %, K2HPO4 0.1 % and MgSO4 • 7H2O 0.05 % (pH 6.2) in a 500-m1 baffled Erlenmeyer flask and cultured for 3 days at 37°C on a rotatory shaker (180 rpm). The culture broth in 37 flasks was collected and filtered at pH 6.4 to give 3.2 liters of the filtrate (22 ug/ml assayed by the cylinder plate method using Bacillus subtilis PCI219 as the test organism and the pure new antibiotic hydrochloride, 890 iLg/mg, as the assay standard). Siomycin produced by S. sioyaensis1) and its related peptide antibiotics could not be found in the filtrate. The antibiotics in the filtrate were adsorbed on a column of Amberlite IRC-50 (Na+ : H+, 7: 3, 240 ml) and eluted with 1 N HCL The active eluate (226 ml) was neutralized to pH 5.6 with Amberlite IR-45 (OH-) and chromato-