Effects of nutrients on the production of AK-111-81 macrolide antibiotic by Streptomyces hygroscopicus.

The influence of different carbon and nitrogen sources on the production of AK-111-81 nonpolyenic macrolide antibiotic by Streptomyces hygroscopicus 111-81 was studied. Substitution of glucose with lactose or glycerol significantly affected maximal antibiotic AK-111-81 productivity as the growth rate was close to that of the basal fermentation medium. Addition of ammonium succinate to the fermentation medium markedly increased the antibiotic productivity as the growth rate was low. Divalent ions as Mn2+, Cu2+, Fe2+ stimulated AK-111-81 antibiotic biosynthesis. These results allow us to develop a new fermentation medium showing 6-fold increase of AK-111-81 antibiotic formation compared with the basal fermentation medium.

Physiological and antagonistic potential of actinomycetes from loquat rhizosphere.

The microflora of Eriobotrya japonica (loquat) was studied by the serial dilutions-spread plate method. A variety of bacteria, fungi and actinomycetes was detected. The genus Steptomyces dominated in the population (83%). A great species diversity was found among Streptomycetes. Some of the actinomycetes possessed antibacterial activity (47%), others produced different exo-enzymes.

Comparative investigation of a streptovaricin-producing strain of Streptomyces spectabilis and its selectant.

Some differences were found in the ultrastructural, cultural and physiological-biochemical properties between the parent strain Streptomyces spectabilis 1000 and its natural selectant S. spectabilis 1011-10, producers of streptovaricin.

Streptomyces species producing the streptovaricin complex.

Morphological, cultural and physiological-biochemical properties of Streptomyces sp. strain 1000 and its antibiotic production were investigated. Antibiotics 1011 (identical with the streptovaricin complex) and 1012 (with antibacterial action) were isolated from the cultural broth of this strain. The overproducing natural variant 1011 was isolated from the population of a strain producing antibiotic 1011 at a concentration of 1000 mg/L (activity of the parent strain represents 41 mg/L only). Comparative taxonomical characteristic of Streptomyces sp. strain 1000 with strains from S. spectabilis showed that the strain 1000 differed in some properties and antibiotic production being considered as a new variant of S. spectabilis. The strain shows an expressed antibiotic activity against G+ as well as G- bacterial and yeasts.

[Biological action of an unidentified factor from streptomycetes]. / Biologichno deistvie na neidentifitsiran faktor ot streptomitseti.

Studied were a total of 926 actinomycetic strains. In 285 of them (27.8 per cent) there was a capacity to synthesize growth factors which stimulated the production of fruit bodies of the mycelial fungus 2x. The culture liquid of two of the producent strains, 210-c and 192-B, was given as a supplement to the ordinary feed ration of albino mice. It was found that birth rate rose twice with the test groups. Histologically, a stimulant action was demonstrated with regard to ovogenesis in terms of the earlier maturation of follicles and formation of corpora lutea both in rats and in 4-5-month-old lambs.