3-N-methylparomomycin I produced by a Streptomyces.

A new member of paromomycin group antibiotics has been isolated from the culture filtrate of Streptoverticillium sp. Al-R2827 which was isolated from a soil sample collected in India. In this report, the production, the isolation, characterization and structural elucidation of the antibiotic are reported. Production and Isolation Streptoverticillium sp. Al-R2827 was inocu-lated into a seed medium (50 ml) containing starch 1.0%, glucose 1.0%, Polypeptone 0.5% meat extract 0.2%, yeast extract 0.3%, soybean meal 0.2% and CaCO3 0.2% (pH 7.0) in a 250-ml baffled Erlenmeyer flask and cultured for 48 hours at 28°C on a rotatory shaker (250 rpm). Twenty-five milliliters of this inoculum was transferred to the same seed medium (500 ml) in a 2-liter flask and incubated under the similar condition for 48 hours. The seed culture (500 ml) was inoculated into a production medium (30 liters) consisting of soybean cake 5.0%, glucose 6.0%, Na2SO4 1.0% (NH4)2HPO4 0.02%, soybean oil 0.3% and silicone defoamer 0.05% in a 50-liter jar fermentor and cultured for 90 hours at 27°C under agitation (580 rpm) and aeration (15 liters/minute). The fermented broth (60 liters) was filtered (45 liters, 5.5 pg/ml of 3-N-methylparomomycin I) at pH 8 using Hyflo Super Cel (Johns-Manville) as the filter aid. The activity of the antibiotics was assayed by the paper disc method using Bacillus subtilis PCI 219 as the test organism. The culture filtrate was passed through a column of Am-berlite IRC-50 (NH4+, 2 liters) and after washing with water, the column was eluted with 1 M NH4OH. The active eluate was concentrated to dryness and the residue was extracted with 80% aqueous methanol. The extract was concentrated. The antibiotics in the concentrate were adsorbed on a column of Amberlite CG-50 (NH4+, 500 ml) and eluted with 0.5 M NH4OH. The active eluate was concentrated to dryness to give a crude powder (1.86 g, 119 pg/mg). On silica gel TLC with chloroform-methanol-28 % ammonia (1: 4: 2), the crude powder showed the presence of two antibiotics at Rf 0.23 and Rf 0.16. The latter was identical with that of paromomycin I. The crude powder (760 mg) was dissolved with a small amount of water and the antibiotics were adsorbed on a column of Amberlite CG-50 (NH4+, 100 ml). After washing with water (1,000 ml), 0.1M NH4OH (500 ml) and 0.15 M NH,OH (500 ml), the column was eluted with 0.18 M NH4OH and the eluate was cut into …