Interrelationship of polyphosphate metabolism and levorin biosynthesis in Streptomyces levoris

The effect of inorganic phosphate on biosynthesis of the polyene antibiotic levorin by Streptomyces levoris was studied. At phosphate concentration of 4.0 mM levorin biosynthesis is repressed by 90%, resulting in an increase of ATP and a condensed inorganic polyphosphates content in the producer cells. At phosphate concentration optimal for levorin production (0.04 mM) the level of intracellular ATP sharply falls by the beginning of the steady-state phase of the producer growth and that of polyphosphates decreases 3-6-fold. The inorganic phosphate exerts different effects on polyphosphate metabolism enzymes, such as polyphosphate: D-glucose-6-phosphotransferase, polyphosphate phosphohydrolase, tripolyphosphate phosphohydrolase, pyrophosphate phosphohydrolase, alkaline and acid phosphatase. The strongest effect of phosphate excess is observed in the case of polyphosphate: D-glucose-6-phosphotransferase, whose activity decreases 2-5-fold. The activity of this enzyme was shown to be correlated with the antibiotic accumulation. The data obtained are indicative of interrelationship between the polyphosphate metabolism and levorin biosynthesis.     

Variability of the levorin producer, Actinomyces levoris Krass]

Natural variation of the levorin-producing organism Act. levoris, strain 28 was studied with respect to the colony morphology and production of levorin and levoristatin. The population of strain 28 consisted of 3 morphological colony types, the main type amounting to 99.7 percent. The strain variation with respect to production of levorin and levoristatin ranged from 20 to 180 and from 0 to 300 percent respectively as compared to the control. Mutant M-28 differing from the initial strain by the colony morphology, moderate phage titer and preferable production of levoristatin was isolated as a result of repeated passages of strain 28 onto agarized Chapek media with starch without maintaining selection. Variants differing from the population of strains 28 and M-28 by the ratio of levorin and levoristatin in the culture fluid were selected. No correlation in production of the above antibiotics by strain 28 was noted. Preparations obtained with strain M-28 differed from those obtained with strain 28 in a significant content of levoristatin.     

Biosynthesis of levorin and activity of several enzyme systems of Streptomyces levoris depending on culture conditions

The regularities of changes in the main oxidation-reduction enzymes of the tricarboxylic acid cycle (TAC) and the pentose cycle were studied under different cultivation conditions: with the use of the control soybean-corn-hydrol medium and the medium with addition of a biostimulant produced by C. tropicalis. It was shown that the activity levels of the dehydrogenase systems of the TAC and the pentose cycle of S. levoris grown in the presence of the biostimulant were higher. The increase in the production levels of levorin due to addition of the biostimulant was connected with the activity of the systems responsible for regeneration of NADP.H2.     

Action of the products of the vital activity of yeastlike fungi on the biosynthesis of levorin, levoristatin and fatty acids by a Streptomyces levoris culture

The data on the effect of the products of vital activity of Candida tropicalis, a yeast-like fungus, on the biosynthesis of levorin, levoristatin and fatty acids by Streptomyces levoris are presented. It was shown that the effect of the biostimulators was not specific with respect to production of levorin, since in the presence of the products of vital activity of C. tropicalis an increase in the synthesis of levoristatin and fatty acids was also observed. The qualitative and quantitative composition of the fatty acids of the mycelium of S. levoris was studied. Interrelation between the biosynthesis of levorin and synthesis of unsaturated fatty acids and branched chain fatty acids was noted.     

Isolation, purification and characterization of levorin produced by Streptomyces levoris 99/23

Levorin produced by Streptomyces levoris 99/23 was isolated, purified and characterized. It was established that 80% of the levorin was localized in the mycelium and only 20% was in the cell-free supernatant. Amorphous yellow levorin with activity of 24 000 IU/mg and 96% purity was obtained. The preparation exhibited three absorption maxima: at λ 362, 382 and 404 nm. The antibiotic contained seven components: A₀, A₁, A₂, A₃, A₄, and two unidentified ones. According to its composition, the preparation corresponded to the levorin used for medicinal purposes. However, the levorin produced by S. levoris 99/23 contained half as much levorin A₂ and a more than 100 times larger quantity of the more active and less toxic component levorin A₃.     

Selective action of novobiocin on Act. levoris, the producer of levorin and levoristatin]

The effect of sodium novobiocin on Act. levoris, strain LIA 0868 producing levorin and levoristatin was studied. High lethal effect of the antibiotic on Act. levoris was found. The effect increased with a rise in the antibiotic concentration in the agar from 2 to 6 lambda/ml. The inhibitory effect of novobiocin on Act, levoris was evident from a marked increase in the number of morphologically changed colonies with a low level of levorin production. The selective effect of novobiocin on the organism producing levorin and levoristatin was evident from selection of variants with high levels of levoristatin production on media containing novobiocin.     

Optimisation of synthetic medium composition for levorin biosynthesis by Streptomyces levoris 99/23 and investigation of its accumulation dynamics using mathematical modelling methods

The composition of a synthetic culture medium for levorin biosynthesis by Streptomyces levoris 99/23 was optimised using mathematical modelling methods. The optimal concentrations of the medium components were established by means of an optimum composition design at three factor variation levels. An adequate regression model was obtained. Levorin biosynthesis by Streptomyces levoris 99/23 in the optimised synthetic medium was over 38% higher than in the initial medium. The antibiotic biosynthesis dynamics in the optimised culture medium was studied by means of a non-linear differential equation system. The resultant model was valid.     

Effect of inorganic phosphorus on the biosynthesis of polymyxin B]

A synthetic medium containing optimal levels of the sources of carbon, nitrogen and inorganic phosphorus and providing satisfactory yields of polymyxin B was developed for 2 strains of Bac. polymyxa 933 and VK-153. The consumption of phosphorus in the medium by the strains and the antibiotic biosynthesis levels depended on the form of phosphorus added to the medium. Optimal biosynthesis of polymyxin B was observed at lower concentration levels of soluble soluble phosphorus in the medium than the bacterial growth.     

Effect of phosphate on the biosynthesis of nourseothricin by Streptomyces noursei JA 3890b

The results present evidence for the important role of phosphate-mediated regulation of the nourseothricin biosynthesis by the processes of phosphate limitation and release of phosphate. Also, higher initial concentrations of phosphate were found to have a strong inhibitory effect on the biosynthesis of nourseothricin. It is concluded that the initial phosphate concentration was the primary target for the biometrical optimization of the fermentation medium. The presence of zinc ions neutralized the negative effect of high initial concentrations of phosphate which was also strongly influenced by the regime of sterilization.     

Regulation of nebramycin biosynthesis by inorganic phosphate

The effect of inorganic phosphate on the biosynthesis of nebramycin factors2, 4 and5′ was studied inStreptomyces tenebrarius strain A (forming2, 4 and5′ in natural ratios) and its mutants B (forming predominantly2), C (forming2 as the only major product) and D (forming predominantly5′). In phosphate-supplemented complex media, the production of2 in A, B and C was reduced by 20–70%, while the yields of5′ remained unchanged in A and decreased by 30–60% in B. The production of4 increased by 50–90% in A and was fully suppressed in B. In D the biosynthesis of the three factors was inhibited completely.     

Effect of concentrations of limiting substrates on the linear growth rates of Streptomyces levoris colonies

The relationship between linear growth rates of S. levoris zone-forming colonies and concentrations of different limiting energy and carbon sources in the nutrient medium has been studied. A formula has been derived satisfactorily describing this relationship. The utilization of the substrates in the source of vegetative and reproductive processes as well as possible mechanisms controlling the periodicity in the life activities of streptomyces colonies are discussed.     

Regulation of avilamycin biosynthesis in Streptomyces viridochromogenes: effects of glucose, ammonium ion, and inorganic phosphate

Effects of glucose, ammonium ions and phosphate on avilamycin biosynthesis in Streptomyces viridochromogenes AS4.126 were investigated. Twenty grams per liter of glucose, 10 mmol/L ammonium ions, and 10 mmol/L phosphate in the basal medium stimulated avilamycin biosynthesis. When the concentrations of glucose, ammonium ions, and phosphate in the basal medium exceeded 20 g/L, 10 mmol/L, and 10 mmol/L, respectively, avilamycin biosynthesis greatly decreased. When 20 g/L glucose was added at 32 h, avilamycin yield decreased by 70.2%. Avilamycin biosynthesis hardly continued when 2-deoxy-glucose was added into the basal medium at 32 h. There was little influence on avilamycin biosynthesis with the addition of the 3-methyl-glucose (20 g/L) at 32 h. In the presence of excess (NH₄)₂SO₄ (20 mmol/L), the activities of valine dehydrogenase and glucose-6-phosphate dehydrogenase were depressed 47.7 and 58.3%, respectively, of that of the control at 48 h. The activity of succinate dehydrogenase increased 49.5% compared to the control at 48 h. The intracellular adenosine triphosphate level and 6-phosphate glucose content of S. viridochromogenes were 128 and 129%, respectively, of that of the control at 48 h, with the addition of the 40 mmol/L of KH₂PO₄. As a result, high concentrations of glucose, ammonium ions, and inorganic phosphate all led to the absence of the precursors for avilamycin biosynthesis and affected antibiotic synthesis.     

Effect of phosphorus on polymyxin B biosynthesis by B. polymyxa 1538 on media of varying makeup]

The effect of phosphorus on biosynthesis of polymyxin B by B. polymyxa 1538 was studied and its optimal concentration in the synthetic and two complex media was determined. Correlation between the culture growth and consumption of the main components, on the one hand, and concentration of phosphorus in the medium, on the other hand, was found. It was shown that the effect of phosphorus on biosynthesis of polymyxin B did not depend on the carbon source in the medium and aeration conditions.