Z. Vaněk

Anhydrotetracycline oxygenase activity and biosynthesis of tetracyclines in streptomyces aureofaciens

SummaryA new method for the assay of the enzyme converting anhydrotetracycline into dehydrotetracycline is described. The enzyme activity increases sharply during the growth phase and reaches its maximum at the beginning of the production phase; it is depressed when the concentration of inorganic phosphate in the cultivation medium is increased.

How many genes are required for the synthesis of chlortetracycline

When contemplating the applicability of the theory of polygenic heredity to the development of views on the genetic regulation of the biosynthesis of secondary metabolites one encounters two extreme concepts. The first assumes that with increasing knowledge of the molecular basis of the biosynthesis of these compounds the views of polygenic heredity (formulated at the beginning of this century) cannot fundamentally contribute to the interpretation of new experimental data and to the formulation of a new working hypothesis in accord with the present state of our knowledge. The second concept proceeds from the simple fact that there is no unified theory of genetics at the present time to account satisfactorily for the heredity of complicated quantitative characters, such as the number of eggs laid, milk production, body weight, the production of various pigments etc. Most geneticists studying the improvement of industrial strains producing antibiotics are of the opinion that an increase in the production of these substances represents a very complicated matter and, basically, possesses all the features of polygenic heredity.

Microbial growth and production of antibiotics.

Antibiotic compounds do not constitute a homogeneous group. From the chemical point of view they are highly heterogeneous and it is difficult to formulate a general hypothesis that would explain the causes of production of these compounds on the basis of data obtained so far (Donovick and Brown, 1965). This difficulty is also reflected by contradictory assumptions concerning the importance of these compounds for production microorganisms.

Immunomodulators isolated from microorganisms

Microbial products are surveyed that have an immunoregulatory activity, both from the realm of low-molar-mass compounds and from the group of naturally occurring polymers. The data include in most cases the producer organism or source, a brief chemical characteristic and biological activity. Various groups of substances are compared, the drawbacks attendant on their acquisition and application are pointed out and their advantageous properties are specified.

Studies on the production of daunomycinonederived glycosides and related metabolites inStreptomyces coeruleorubidus andStreptomyces peucetius

Strains ofStreptomyces coeruleorubiduě ISP 5145,JA 10092 and 39–146, differing mutually in antibiotic activity, were found to produce identical spectrum of metabolites (at least nine antibiotically active glycosides, 13-dihydrodaunomycinone, ε-rhodomycinone and a larger number of unidentified compounds); only trace quantities of daunomycin and daunomycinone could be detected. A fraction of glycosides with a higher Rf (0.4–0.7), isolated from strain 39–146, could be transformed to daunomycin by mild hydrolysis and to daunomycinone by total hydrolysis.Streptomyces peucetius IMI 101 335 differed fromStreptomyces coeruleorubidus in an increased production of ε-rhodomycinone and a lower content of glycosides; the zone of daunomycin was most pronounced among the glycoside spots.Streptomyces coeruleorubidus 39-146 exhibited the highest activity in a medium containing 3.5% soluble starch, 3.0% soybean meal, 0.3% NaCl and 0.3% CaCo3; glucose was a more useful carbon source for the remaining strains The activity ofStreptomyces coeruleorubidus was inhibited by 1-propanol, Na-propionate,5,5-diethylbarbiturate and bacitracin. Ferrous sulphate stimulated the production of glycosides only in strain JA 10092, decreasing simultaneously the production of aglycones.

Biotransformations of anthracyclinones inStreptomyces coeruleorubidus andStreptomyces galilaeus

The ability to transform biologically exogenous daunomycinone, 13-dihydrodaunomycinone, aklavinone, 7-deoxyaklavinone, ε-rhodomycinone, ε-isorhodomycinone and ε-pyrromycinone was studied in submerged cultures of the following strains: wildStreptomyces coeruleorubidus JA 10092 (W1) and its improved variants 39–146 and 84–17 (type P1) producing glycosides of daunomycinone and of 13-dihydro-daunomycinone, together with ε-rhodomycinone, 13-dihydrodaunomycinone and 7-deoxy-13-dihydro-daunomycinone; in five mutant types ofS. coeruleorubidus (A, B, C, D, E) blocked in the biosynthesis of glycosides and differing in the production of free anthracyclinones; in the wildStreptomyces galilaeus JA 3043 (W2) and its improved variant G-167 (P2) producing glycosides of ε-pyrromycinone and of aklavinone together with 7-deoxy and bisanhydro derivatives of both aglycones; in two mutant typesS. galilaeus (F and G) blocked in biosynthesis of glycosides and differing in the occurrence of anthracyclinones. The following bioconversions were observed: daunomycinone → 13-dihydrodaunomycinone and 7-deoxy-13-di-hydrodaunomycinone (all strains); 13-dihydrodaunomycinone → 7-deoxy-13-dihydrodaunomycinone (all strains); daunomyeinone or 13-dihydrodaunomycinone → glycosides of daunomyeinone and of 13-dihydrodaunomycinone, identical with metabolites W1 and P1 (type A), or only a single glycoside of daunomyeinone (type E); aklavinone → ε-rhodomycinone (types A and B); aklavinone → 7-deoxyaklavinone and bisan-hydroaklavinone (type C); ε-rhodomycinone → ζ-rhodomycinone (types C, E); ε-rhodomycinone → glycosides of ε-rhodomycinone (types W2, P2); ε-isorhodomycinone → glycosides of ε-isorhodomycinone (types W2, P2); ε-pyrromycinone → a glycoside of ε-pyrromycinone (types W1, P1). 7-Deoxyaklavinone remained intact in all tests. Exogenous daunomyeinone suppressed the biosynthesis of its own glycosidea in W1 and P1; it simultaneously increased the production of ε-rhodomyeinone in P1.

Fatty acids ofStreptomyces cinnamonensis, producer of monensin

Using the gas chromatography-mass spectrometry (GC-MS) method we found inStreptomyces cinnamonensis saturated fatty acids of iso-and anteiso-types, cyclopropyl acids, and unsaturated fatty acids where the double bond position was determined by MS of their pyrrolidine derivatives.

Regulation of biosynthesis of monensins on chemically defined medium.

Addition ofL-valine andDL-isoleucine to the cultivation medium ofStreptomyces cinnamonensis was found to affect the ratio of synthesized monensins A and B. In the presence ofL-valine monensin A is synthesized predominantly, whereas in the presence ofDL-isoleucine the production of monensin B increases.

Improving the production of monensin byStreptomyces cinnamonensis

The production of monensin byStreptomyces cinnamonensis was increased by genetic improvement of the strain and by modification of cultivation conditions. The selection of a suitable strain and optimization of the fermantation process (temperature, aeration, addition of esters of oleic acid) resulted in a 30 fold increase of the monensin production.

The study of variability and strain selection inStreptomyces atroolivaceus

A seven-step selection procedure (repeated UV irradiation, single-step application of nitrous acid, and natural selection, following each mutagenic treatment) made it possible to increase production of mithramycin byStreptomyces atroolivaceus from 40–50 μg/ml to 680–830 μg/ml,i.e. roughly by 15 to 19-fold. The UV radiation was more effective when applying lower doses, yielding about 5% survival, 2.3% survival was obtained after the treatment with nitrous acid.N-Methyl-N′-nitro-N-nitrosoguanidine applied in a buffer pH 9.0) at doses yielding more than 99% killing was less effective than the two former mutagens.