A new peptide antibiotic KM-8.

In the course of screening for new antibiotics, a strain of a new species belonging to Streptoverticillium was found to produce a new peptide antibiotic. Most of the procedure used in the taxonomic study of the strain were carried out in accordance with the method adopted by the International Streptomyces Project (ISP)1) Additional media recommended by WAKSMAN2,3) were also used. From the morphological characteristics, the strain KM-8 was shown to belong to the genus Streptoverticillium. That is, several short branches are formed in a whorl at regular intervals along the aerial mycelium, and about 1050 oval-shaped spores with smooth surface formed a chain. The color of the colony was white to yellow, and that of the reverse side of the colony was light yellow on glycerolasparagine agar and pale yellowish brown on glucose-nitrate agar. A soluble yellow pigment formed on oat meal agar and a pale brown pigment formed on glycerol-asparagine agar, while melanoid pigments were not formed. 'This strain was examined in detail to be compared to the strains, Streptomyces morookaensis ISP 5503, Streptoverticillium griseoverticillatum ISP 5507 and Streptomyces kobenensis KA-410, which most resemble the characteristics of the strain KM-8. From the result of these taxonomic studies, this strain was found not to belong to any known species, and named Streptoverticillium taitoensis since it was isolated from the soil sample collected in Taito-ku, Tokyo. The antibiotic KM-8 was produced by shaked flask or submerged cultures in the medium containing 3.0 % starch, 0.5 % ammonium sulfate, 0.5 % yeast extract and 0.3 % calcium carbonate for 150-170 hours at 27'C. The cultured broth was filtered and passed through a column of Amberlite XAD-2. The resin column was washed with water and 10 % aqueous acetone. The active substance was eluted with 50 % aqueous acetone, and concentrated in vacuo to an aqueous solution. The active substance was then adsorbed on the Amberlite XAD-7 column and also eluted with 50 % aqueous acetone after the resin had been washed with water and 10 % aqueous acetone. The eluate was concentrated in vacuo and adsorbed on a silica gel dry column. The column was washed with water and then chromatographically developed with 40 % aqueous ethanol. The active fractions were collected and concentrated to be aqueous solution. KM-8 was obtained as a white powder by lyophilizing the concentrated solution. It was observed to be a single spot on thin-layer chromatography in several solvent systems. The KM-8 substance is a white powder having a basic nature (pKa 8.7 in H2O), and decomposes at 240°C. It is soluble in water, slightly soluble in methanol and ethanol, and insoluble in acetone, ethylacetate, chloroform, benzene, ether and hexane. The UV spectrum in water shows four maxima at 252 nm (E1%1cm 5.13), 258 nm (E1%1cm 5.20), 264 nm (E1%1cm 4.51) and 268 nm (E1%1cm. 3.79) as shown in Fig. 1, which may result from phenylalanine detected in the hydrolyzate of this antibiotic. The IR spectrum in KBr disc is shown in Fig. 2. From the absorption maxima at 3300,