The Production and Purification of Phytoactin B-¹⁴C from Streptomyces Hygroscopicus

SUMMARY

Streptomyces hygroscopicus (NRRL-2752) was cultured on a select medium to produce phytoactin. The medium required soy hydrolysate. Agitation plus aeration also were necessary. The antibiotic was located only in mycelial elements and was extracted with isopropanol. Desiccated mycelium was processed to isolate phytoactin B (yield = 15.7 mg/gm). The material was equated with reference standard phytoactin B on all reported physical and chemical characteristics as well as on biological activity against Colletotrichum gloeosporioides. The antibiotic was tagged by amending the medium with uniformly labeled acetate-¹⁴C (yield = 16.2 mg/gm desiccated mycelia; level of activity = 7,385 cpm/mg phytoactin B). The isolated phytoactin B and the reference standard were fractionated by TLC on silica gel plus phosphor and binder. DEAE cellulose and neutral aluminum oxide did not induce fractionation. On silica gel, phytoactin B-¹⁴C was demonstrated to fractionate such that biological activity was associated with from only 11 to 20% of the parent material. The biologically active fraction quenched far UV but not near UV. All the biologically inactive fractions fluoresced variably under far and near UV illuminations. It was demonstrated that the biologically active fraction purified on silica gel had 15% greater biological activity than the unseparated reference standard.