Abstract: Boholmycin antibiotic is prepared by fermentation of Streptomyces hygroscopicus H617-25 (ATCC No. 53240) in a nutrient medium preferably comprising glycerol, bacto-liver, cornsteep liquor, ammonium sulfate, sodium chloride and calcium carbonate. The antibiotic and pharmaceutically acceptable salts and hydrates thereof and compositions containing these are effective against Gram-positive, Gram-negative and acid-fast bacteria and against bacterial strains which are resistant to previously known aminoglycoside antibiotics and are useful to treat bacterial infections in mammals.