A conidium-producing variant of Streptomyces griseus, strain 45-H, produces a substance, factor C, which is capable of inducing conidium formation in the hyphae of a conidium-non-producing mutant, strain 52-1. Factor C can be determined quantitatively on the basis of this biological effect. The biologically active substance can be purified by ion-exchange chromatography on cellulose phosphate combined with affinity chromatography on DNA-agarose. The purified substance is concentrated at least 1700 times. The molecular weight of factor C, estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate, is about 34500. On determining the amino acid composition of factor C 60 % of the amino acids were found to be hydrophobic.Cytodifferentiation has been studied in Streptomyces griseus strains [l, 21. From the fermentation liquid of the conidium-producing S. griseus 45-H strain a substance (designated factor C) has been isolated which, if added to the culture medium of the otherwise non-differentiating S. griseus 52-1 strain, has been found to elicit various cytomorphological signs of conidium formation [3,4].In our previous papers [3-61 we have already described the most apparent features of the effect of this endogenous substance which induces differentiation.In the present paper the process of the purification and the chemical properties of factor C are described. MATERIALS AND METHODS Production of Factor CStrain 45-H, a mutant of Streptomyces griseus, was cultivated in 10 1 of filtered soybean medium in a MicroFerm fermentor, model MF-114 (New Brunswick Scientific Co., Inc., U.S.A.), operating at an airflow of 6 l/min at 27 "C. Cultivation was continued for 66-72 h when conidia, or reproductive hyphae, appeared in a large number. Detection of Factor CFactor C can be detected on the basis of its effect inducing cytomorphological changes in the submerged culture of S. griseus 52-1. Its effect was evaluated with a phase-contrast microscope in 72-h submerged cultures of the test strain after glutaraldehyde fixation. The test was regarded positive if formation of reproductive branches could be detected in the test strain which otherwise did not produce conidia. Estimation of the Quantity of Factor CSerial dilution was performed and the amount of factor C found in 1 ml of the highest dilution still definitely positive was taken as unit. Removal of the MyceliaThe pH of the culture filtrate of S. griseus 45-H was adjusted to 6.5 with 2 M HzS04 and after the addition of 0.001 M EDTA the mycelia were centrifuged by a continuous-action rotor at 21 000 x g in an MSE high-speed 18 centrifuge at 4°C. After centrifugation the pH of the culture filtrate was adjusted to 4.5 with 2 M HzS04. Ion-Exchange ChromatographyTwo steps of ion-exchange chromatography were used consecutively.Batchwise Method. 60 g precyclized, equilibrated and fines-free Whatman P-1 cellulose phosphate were added to the 10-1 culture filtrate. Then the mixture was kept in a cold room for 2 h while being stirred continu-

No abstract

No abstract

No abstract